AP42 Section: 11.25 Reference:
~ Title: Clays,
S. H. Patterson and H. H. Murray,
Industrial Minerals And Rocks, Volume 1, Society Of Mining Engineers, New York, 1983.
The term clay is somewhat ambiguous un- less specifically defined, because it is used in three ways: (I) as a diverse group of fine- grained minerals, (2) a5 a rock term, and (3) as a particle-size term. Actually, most persons using the term clay realize that it has several meanings, and in most instances they define it. As a rock term, clay is difficult to define be- cause of the wide variety of materials that com- ,me it; therefore, the definition must be gen- 'eral. Clay is a natural earthy, fine-grained ma- Iterial composed largely of a group of crystalline ;minerals known as the clay minerals. These minerals are hydrous silicates composed mainly of silica, alumina, and water. Several of these minerals also contain appreciable quantities of iron, alkalies, and alkaline earths. Many defini- tions state that a clay is plastic when wet. Most clay materials do have this property, but some clays are not plastic; for exaniple, halloysite and flint clay. As a particle-size term, clay is used for the category that includes the smallest particles. The maximum-size particles in the clay-size grade are defined differently on various grade scales. Soil imestigators and mineralogists gen- erally use 2 micrometers as the maximum size, whereas the widely used scale by Wentworth (1922) defines clay as material finer than ap proximately 4 micrometers. Some authorities find it convenient to'use the term clay'for any fine-grained, natural, earthy, argillaceous material (Grim. 1968). When used this way, the term includes clay, shale,. or .ar- gillite, and some argillaceous soils.
: * Publication authorized by the Director. US Geological Survey. For other Acknowledgments. see pp. 642-643. t US Geological Survey, Reston. VA. $Georgia Kaolin Co.. Elizabeth, NJ: pres- ently, Dept. of Geology, Indiana University, Bloomington, IN. :.',
. ~-. 586 Industrial Minerals and Rocks in 19t -1969~ on ka Confe ratosa Bentonite 4,467,605 88.425.737 . 4i422.075 106,528.550 4,184,619 115,234,996 Sev Fuller's earth 1,529,619 73,430,515 1.568247 81,761.964 1,533,803 79,724.017 , umes Kaolin 6,973,314 367.782.408 7,760,600 462,320,088 7,878,993 527,098.w9 few yq Ball clay 936,251 21,549,559 987,012 26,119,965 893,624 26,844,126 with r Fire clayt 3,125,953 42,561,432 2,932,343 47,178.993 2,095,361 36,022,134 aby i Miscellaneous : '. i Miner I clay 40,074,738 124,068,443 37278.803 122,735.1 17 32,494,837 114,700,246 (Lon< includ Total* 57,107,430 717,818,034 54,949,080 846,644,677 49.081237 899.624.128 -' therm _I one c Source: Ampian. 1980: Ampian and Polk, 1981. -~ .'"+ ; Definitions of classes of clay listed are given in the appropriate places in the text. ~ ., - StrUCtl t Fire clay is used with essentially the same meaning as refractory clay in this chapter. Fire clay is also the (1961 only type of clay having a sharply declining production in recent years. This is due mainly to the method invest of reporting, in which some types of fire clay used for other than refractory products are now classified ai volum miscellaneous clay, and to the increasing use of higher quality and more durable refractory materials. erals I tlncludes Puerto Rico. i .~.. and \i . ... . ', of Thf (1970 tion o fuller's earth is actually bentonite. The over- of the contributions, mainly in clay mineralogy. chemii lapping of the two terms is particularly evident have been made, so that those who are inter- Olphe where both bentonite and nonbentonite fuller's ested can find detailed information not included lished earth are used for the same purposes or prod- in this report. fractic ucts, such as in drilling muds, bleaching or A vast amount of new information on the volum clarifying fats and oils, and carriers for insecti- mineralogy, geology, and technology of Clays geolog cides and fertilizers. Kaolin. ball clay, halloysite, has become available in recent years. One Of in cer and refractory clays are grouped together be- the principal sources is The Clay Minerals s03- shaw cause they consist mainly of minerals of the ety. This professional and scientific society yolum kaolin group. Miscellaneous clay and shale is organized in 1963 from an informal group one. b a grouping of several fine-grained materials of sponsored and partially supported for the PIC- lated I the type referred to as common clay in some ceding years by the National Academy of %I- cia1 P: reports. ences-National Research Council. For five Yea? ! by We The scientific and technological publications after that date, the papers presented at the SWt- pertaining to clays are so numerous that to erable ety's annual meetings were published in YOI- ..relate1 cover all the material in the format used for umes by Pergamon Press. Since 1968, The Clay other chapters would require a book. Therefore, Anoth Minerals Society has published its own journal (1973 the authors have attempted to .summarize the under the title Cloys and Clay Minerals. A subject matter and wherever possible have indi- of cla second major source of information on clays, formu cated by bibliographic reference where more the publications of the Association Inteptlw ._ detailed information is available. For example, nale pour I'Ptude des Argiles (AIPEA); thy Ag technc the reference to Bicker (1970) is to a bulletin publications are principally volumes containlnB lished containing only brief summary information on the papers presented at the triennial meetlnt7 geolog the. economic geology of bentonite in Missis- of the association. A third e.yellent source Of sippi, but that bulletin contains references to information on clays is Clay Minerals, the jour- agenci virtually all published reports on bentonite in nal of The Clay Minerals Group of The Miner- Of thi Part 3 that state. : alogical Society (London). In addition. Clay The remaining parts of this introduction will minerals groups or societies in France, Spain* here; be mainly an outline of some of the major ad- Italy, Japan, Argentina, West Germany. and impor vancements in the broad field of clays since the other countries have periodic publications. Con- the fo 4th edition of Industrial Minerals and Rocks siderable information on kaolin resources i" Ma (Patterson and Murray, 1975) and acknowl- several countries is available in three vOlumn ous cl edgment to those who have helped in preparing resulting from a symposium held at the Inter these I this chapter. Our intent is to note where some national Geological Congress in Czechoslovak'a advan .. Clays in 1968 (Malkovskj. and Vachtl, 1969a, 1969b, new uses, shifts in demand, and increases in 1969~)and in the report of another symposium both domestic and export markets. The chang- on kaolin held at the 1972 International Clay ing conditions, particularly increasing freight rates, the energy crisis, other production and Value I marketing costs, and the pressures brought - Several major textbooks and reference vol- about by governmental controls and mining 158234.996 laws resulting from requirements and restric- 79,724,017 umes on clays have been published in the last 527.098.6og few years. They include one concerned mainly tions related to environmental considerations, 26,844,126 with mineralogy and another on applied miner- etc., have motivated the formation of organiza- 36,022,134 alogy of clays by Grim (1962, 1968). The Clay tions to look after the interests of some of the -. Minerals Group of the Mineralogical Society clay-producing industries. One of these organi- 114,700,246 (London) has a classic series on clay minerals, zations formed recently is the Absorptive Min- - including a. volume concerned with differential erals Institute, having headquarters at No. 1 899,624.128 thermal analysis, edited by Mackenzie (1957), Illinois Center, 1 I1 E. Wacker Drive, Chicago, - one on the X-ray identification and crystal 1L 60601. This institute was formed mainly to structures of clay minerals edited by Brown represent the producers of absorbent granules lay is also the (1961). and a third on the electron-optical and other fuller's earth products. A similar :o_themethod investigation of clays edited by Gard (1971). A organization, the Bentonite Producers Associa- N CEfsiiird as volume on the electron microscopy of clay min- tion, was organized in 1971 in Casper, WY, .Y materials. erals has also been prepared by Beutelspacher and represents the interests of the producers of and Van Der Marel (1968). A Special Paper bentonite. The kaolin industry organized the of The Geological Society of America by Carroll US Clay Producers Traffic Association which .. - was incorporated in 1953 in New Jersey. In tion of clays. An excellent volume on colloid addition to these organizations dealing specifi- ? mineralogy. chemistry of clays has been authored by Van cally with clays, the clay industry and other ho are inter. 1. In 1967, Zvyagin (1967) pub- mining industries formed mining associations not includcd lished a book concerned with the electron dif- in many states, including Georgia and Texas in sis of clays. Gillott's (1968) 1972, in order to protect their interests against ation on thc restrictive state and federal legislation. ogy of clays geology. Recent volumes concerning clays used :an. One 01 in ceramic materials include books by Grim- Bentonite and Fuller's Earth Iinerals Soci- .shaw (1972) and Clews (1969). An excellent c society wa, volume on the geology and origin of clays is ormal. group one by Millot (1964), which has been trans- Definitions and Classifications for the pre. lated'frpm French into English. A recent Spei';. demy of Sc-- The term bentonire was first proposed in cia1 Paper of The Geological Society of America 1898 by Knight (1898), a year after he had For five years -by Weaver and others (1972) contains consid- d at the soci- named this clay taylorite; taylorite was found to erable information on the geochemistry of clays be preoccupied. The name taylorite was after !shed in YOI- related to diagenesis and metamorphism. 168, The Cia!. the Taylor ranch, the site of the first mine, near Another recent volume by Weaver and Pollard Rock River, WY, and the name bentonite is own journal (1973) contains information on the chemistry Minerals. A from the Benton Shale in which the clay was in on clays is thought at that time to occur. The Benton Shale was, in tum;named after Fort Benton, MT, ,n Internatio- '. A great deal of information on the geology, located more than 400 miles north of Rock [PEA); therc technology, and uses of clay-has also been pub- es containinE River. lished by various provincial, state, and federal Early in the 20th century, several geologists -. oial meeting, ent source recognized that bentonite, mainly in beds in d Cretaceous and Tertiary rocks, originated from rals, the jour. .of the major reports are listed by Hoy in transported volcanic materials. This recogni- ,f The Miner. -Part 3 of Volume 1 and will not be repeated tion led to definitions based on origin, the one Iddition, Ch! here; however, reference to some of the more most widely quoted and generally accepted by rance, Spain. geologists is the following definition by Ross wmany. 3nd and Shannon (1926): .. ications. Con- ing sections of this chapter, resources In Bentonite is a rock composed essentially '" hree vo~umt' of a crystalline clay-like mineral formed by ~ at the Inter- devitrification and the accompanying chemi- . . zechoslovakia cal alteration of a glassy igneous material, . . _..-.. usually il tuff or volcanic ash; and it often swell moderately and to form gel, of lesser'vol. i The I contains variable proportions of accessory umes than equal masses of the sodium type. .$ this t crystal grains that were originally pheno- Bentonite, because of the general relationshipof : morp crysls in the volcanic glass. These are feld- swelling and exchangeable ion characteristics. h 1 ; attem spar (commonly orthoclase and oligoclase), commonly divided into the high-swelling or ., was v biotite, quartz, pyroxenes, ziicon and vari- Dayti ous other minerals typical of volcanic rocks. sodium, low-swelling or calcium, and moderate. The characteristic clay-like mineral has a swelling or intermediate types. The term sub- - bento micaceous habit and facile cleavage. high bentonite (Davis, Vacher, and Conley, 1940) . t sleeve birefringence and a texture inherited from is used inconsistently in industry for the low or type 1 volcanic tuff or ash. and it is usuallv the moderate-swelling varieties. The authors believe Th mineral montmorillonite, but less often the use of this term should be discouraged be- catch beidelite. cause of its implication of a low quality or low mater value and the lack of a mineralogical or ux ', 1 and c ' The difficulty in applying the foregoing defi- basis for it. -+;::,:t!5.. -__ i or m nition to bentonite as an industrial mineral com- In the United States bentonite also classi- term modity is that it is based on origin and is is fied by geographic location and the uses for plied restrictive to an ash, tuff, or volcanic glass which it is sold. Inasmuch as most of the low- wool, parent material. Therefore, bedded deposits swelling calcium type occurs in states bordering from consisting of the clay minerals required by this the Gulf of Mexico, this variety is commonly centu definition but having uncertain origin or.parent called Southern bentonite. The largest-high- fullin, materials cannot properly be called bentonite. swelling sodium bentonite deposits and the purif] Furthermore, many deposits in the western: major producing districts are in-Wyoming and the te United States and in other countries that have adjacent states. Therefore, this bentonite is this u! formed from rocks other than the types re- commonly called Wyoming or Wertern type. Ex> quired by the definition are being mined and Such terms as drilling mud bentonite, foundry mine, sold as bentonite. bond bentonite, and taconite bond bentonite the vi Perhaps the best definition of bentonite as an relating directly to use are applied in marketing. the g industrial mineral is one given by R. E. Grim in Other terms including high and low-yield ben- earth, a plenary lecture at the International Clay Con- tonite, high and low-gel bentonite, and high and troleu ference (AIPEA) at Madrid, Spain, June 27, low-strength bentonite are also used to dis- mean According to this redefinition, which will 1972. tinguish different grades. for th be used in this chapter, bentonite is a clay con- majoi sisting essentially of smectite minerals (mont- The varied classifications notwithstanding. bentonite occurs in so many different varieties howe morillonite group of some usages), regardless of many origin or occurrence. This definition solves the that some cannot logically be classified accord- ing to any of the foregoing groupings. One of sorbei problem of the difference between the geologic the pi and industrial usages of the term and overcomes these types is hectorite, which is a high-swelling lithium-bearing variety of smectite occurring certai the difficulty in assigning a name to smectite mainly in California and adjacent states. It is, absorl clay that formed from igneous rock other than ..... modif ash, tuff, or glass, or those of sedimentary or therefore, not a Wyoming type, and it occur3 uncertain origin. However, bentonite, when even farther west than the so-called westem Thl used with this meaning is stal a rock term (con- bentonites. Others are bentonites having mag- ler's e sisting of more than one mineral), and it will nesium (Mg'+) or hydrogen (H-) as the most havin. not be possible to distinguish it from fuller's abundant or dominant exchangeable ion. These meani earth in many instances. types are neither sodium nor calcium varieties, sense. and apparently some are low swelling, whereas One way of classifying bentonite is based on nafur. its swelling capacities when wet or added to others have rather high-swelling capacities. clays water. Bentonite having sodium (Na') as either Still another type of bentonite, the so-called altere the dominant or as an abundant exchangeable potassium type, K-bentonite, 6r metatientonite. called ion typically has very high swelling capacities occurs in Ordovician and other Paleozoic rock: 1972' and forms gel-like masses when added to water. at many places in Appalachian and MissiisiPPl ing e, Bentonite in which exchangeable calcium (Ca++) Valley regions and elsewhere. This bentonite, activc is more abundant than other ions has much which is generally thought to have formed from activ;: lower swelling capacities than sodium varieties. volcanic ash, consists mainly of illite and mixed- active Some calcium types swell little more than com- layer minerals. Smectite minerals are ordinarjlY the t mon clay, and most crumble into granular present in only minor quantities. Because of 11s there! masses in water. Intermediate calcium-sodium mineral composition, this bentonite contains aP ing i: bentonites, the so-called mixed types, tend to preciably more potassium than most other types. clay i
., .. ..,_ . .i. - ...... _..
The meta prefix originates from the idea that variety of absorbing purposes which are differ- this bentonite was altered by low-grade meta- ent from that of processing oils. morphism or diagenesis. Apparently, the only attempt to use K-bentonite in the United States History and Use was when five or six carloads were mined near Dayton, Rhea County, TN, about 1928; this Bentonite: Bentonite mining began on the bentonite was used for purifying lard (Gilder- Taylor ranch near Rock River, WY, in 1888. sleeve, 1946), and no further mention of this This bentonite reportedly was shipped crude to type will he made. .. Philadelphia where it sold for $25 a ton and was The term fuller’s earth is more or less a used in making cosmetics, A mine was opened in the Upton, WY, district on the western side .i catchall for clay or other fine-grained earthy 1 -material suitable for bleaching and absorbent of the Black Hills in 1903. The early method of and certain other uses: It has m compositional drying was to rake the bentonite by hand over .. or mineralogical meaning. The origin of the steel plates heated by wood or coal fires. term dates hack into antiquity; it wa-. first ap- The date of the fint mining of southern plied to material used in cleansing and fulling bentonite is somewhat conjectural because of - wool, thereby removing the lanolin and dirt the confusion between the terms bentonite and ~.from it. When in the latter half of the last fuller’s earth. One fuller’s earth deposit near ‘century it was found that some earths used for Gonzales, Texas, that is almost certainly bento- fulling would also serve in decolorizing and nite was mined as early as 1906, and another . purifying mineral, vegetable,^ and animal oils, deposit in that same state mined during the Civil ”- .!the term fuller’s earth was modified to include War (Lang et al., 1940) may also have been bentonite. Large-scale mining of calcium-type . :’ this usage. z Extensive use of fuller’s earth in processing bentonite began in Mississippi in the early 1. mineral oils in the first half of this century and 1930s (Bicker, 1970), and bentonite deposits the virtual end of its use in fulling fiber led to were used as fuller’s earth in several states about this time. -‘the general application of the term, fuller’s earth, as meaning primarily earth used in pe- The value of bentonite as foundry-sand bond troleum processing. Further modification of the was recognized in the 1920s. and the iron and meaning came about as other uses develoned steel foundries have since been major consum- for theiarth and replaced oil processing as-the ers of bentonite. Bentonite was first used as major use. The term fuller’s earth is retained. drilling mud in the late 1920s or early 1930s, however, for fine-grained materials used fo; and bentonite is still one of the most efficient many purposes.~Mostof these uses require ah- materials for drilling muds where the rocks sorbent properties.in one form or another, hut penetrated contain only fresh water. The high- the properties required for some uses, such as ., swelling Wyoming bentonite is the most efficient . certain drilling muds and fillers, are other than type for drilling mud, hut the high-viscosity . absorbency and, therefore, result in further properties of hectorite make it useful in muds modification of the term. (Larsen, 1955). Some Texas bentonite is also -.__ used for drilling muds, particularly in shallow E. The classification and understanding of ful- wells, and commonly it is treated with soda ash, ’. ler’s earth are also comulicated hv several terms I’ polymers, or other chemicals to make it suitable i: having more or less duplicate or overlapping for this use. Low-quality bentonite when sold :meanings. When applied in the oil-processing _.- sense, fuller’s earth has the same meaning as for use in drilling mud is commonly classified
u) where in rec c is used foi 0 3,500 .-c multiplecol 0‘ Fuller’s I .c 3,000 u) confusing a 0 earth in tht c 0 2,500 fuller’s eart u) 3 I893 near C 0 Co. (prede f 2,000 White Ow: W brick from, -I- z I .500 was not st 2 Alsatian im z recognized W I,O00 mined in G m velopment .* years later : 500 .. ing mineral on a small 0 (Miser, 19 1965 1967 1969 1971 1973 1975 1977 1979 1981~ fining of co YEAR .. - .Both of _- lated to thc .. .:--- . -. oils and fai FIG. I-Benfonife sold or used by domestic producers for specified uses .. poses. Cla: (Ampian, 1980, 1983). i, ., .;:..+ undoubted1 _:. j-__ - ,, .- . .. . Europe in I. . .: ..,.&~- ’ I Little effor . . ..- 1 ;>..::. , . . --. records an< - zn+ -, .. that soldie: refining, filtering, clarifying, and decolorizing), loidal fillers for certain types of paints, an addi- used Woo .. drilling mud, iron-ore pelletizing, and foundry- tive tn ceramic raw materials to increaz skins durii sand bonding have been the major uses of plasticity, fire-retarding materials, and for many Smock, 1: bentonite since World War II (Fig. I). Begin- other purposes (Papin, 1964). The white ben. an iron-ol ning about 1950, steel companies used Wyn- tonites occurring in Texas and Nevada and im- mined in t ming-type bentonite as a bond for pelletized ported from Italy are ,particularly suitable for fuller’s ea : taconite ore. This use grew rapidly, and in many of the speciality products, and a great used to t recent years approximately one-third of the na- deal of research evaluating them for many Uses (Lang et tional production has been used for this pur- has been done. One of the unique uses of h@ were rep0 pose. swelling bentonite that is likely to increase iS In ing blanke In addition to the major uses, bentonite is the “slurry trench’ or “diaphragm wall” method cleansing used in’many miscellaneous products. and hun- nf.excavation in construction in are>s of uncon- period. dreds of patents for speciality uses have been solidated rock or soil (Blackman, 1969; La!%* The use issued or applied for. The speciality uses in- 1971). In this method, the trench or hole being continued clude filtering agents (one of which is a high- excavated is filled with bentonite slurry and the The dema value product for clarifying wine, and another earth being excavated is removed through it., A mineral oi is a less costly one for treating waste water), thin filter cake on the walls of the excavatlOn this centu water impedance (preventing seepage loss from prevents loss of fluid, and the hydrostatic head mately 31 reservoirs, irrigation ditches, and waste-disposal of the slurry prevents caving and running of of the tc ponds, and seepage through basement walls. loore soils, which makes costly shoring unnecev year. The tunnel walls, and other structures), ingredients sary. Considerable quantities of bentonite were purpose I in cosmetics, animal feed, pharmaceuticals, col- Once used in making catalysts for petroleum re- cially whe fining, but the market for these types of cata- 1937 and magnesium silicate in 1940 as more lysts in the United States declined after World efficient substitutes. The market for this use War 11. However, sizable quantities of catalysts was also depressed by improvements in refining have been produced from bentonite and similar methods, which produce oils requiring little clays in Japan, the United Kingdom, and else- purification or bleaching. In recent years, the where in recent years. Acid-activated bentonite production of fuller’s earth for use in refining . is used for bleaching oils and in making mineral oils has maintained a rather uniform multiplecopy paper requiring no carbon paper. rate of 35,000 to 40,000 tpy. The use of fuller’s z~ Fuller’s Earth: Published reports give rather earth in .processing animal and vegetable oils confusing accounts of the discovery of fuller’s has never been a major one and has decreased . earth in the United States. Several.state that to the point where it is included as a part of . fuller’s earth was discovered in this country in the miscellaneous uses in the US Bureau of . 1893 near Quincy, FL, by the Owl Commercial Mines Minerals Yearbooks. ? Co. (predecessor of the present makers of Palygorskite (attapulgitej fuller’s earth was .. -.. White Owl cigars) during an attempt to burn first sold for drilling mud in 1941. The mar- :’. brick from clays on tobacco property. ‘The clay ket for this use expanded slowly and has “r was not suitable for making brick, hut an maintained a level of 7 to 10% of the total -. -5 Alsatian immigrant employed as a farm worker United States production during the last few 2 recognized that it was similar to fuller’s earth years. Most of the fuller’s earth sold for drilling :.. mined in Germany. His observation led to de- mud comes from the southern part of the * velopment of the first mine near Quincy two I- Meigs-Attapulgus-Quincy district of Georgia ,years later and to the use of this clay in process- and Florida. Palygorskite clays produced in this ? iog mineral oils. Fuller’s earth had been mined area are superior to most other fuller’s earth =<. on a small scale, however, in Arkansas in 1891 3 for muds used in drilling salt formations, but . 7 (Miser, 1913), and tested for use in the re- because of high water loss, they are inferior to fining of cottonseed oil. bentonite where the rocks drilled contain no -. Both of these reported discoveries are re- saltwater. lated to the use of fuller’s earth in processing Fuller’s earth was used in significant quanti- . oils and fail to note its earlier use for other pur- ties as a carrier for insecticides and fungicides poses. Clays and other earthy materials were by 1950, and the market for this use has grown . undoubtedly used by the early settlers from at a rather uniform rate since that year. In __ Europe in cleansing wool and other materials. 1979, nearly 14% of the fuller’s earth produced Little effort was made to search the historical was used for this purpose. ji c. records and to document this, but it was found The use of fuller’s earth granules for absorb. : that soldiers stationed near Perth Amboy, Nl, -knt purposes began during the 1930s, but this an addi. .. used Woodbridge fire clay for cleansing buck- use did not expand significantly until the World increosc :. skins during the Revolutionary War (Cook and War I1 period when fuller’s earth was used or man! .- Smock, 1878). Fuller’s, earth associated with as an absorbent for greases, oil, water, chemi- lite hcn. 7 an iron-ore bed near Kent, CT, had been cals, and other undesirable substances on and im- ,. mined in the early 1800s (Silliman, 1820j, and the floors of factories, filling stations, canning fuller’s earth near Falls City, Texas, had been able for = plants, aircraft hangers, decks and engine rooms a grcal ’used to bleach sugar during the Civil War of ships, and other installations. The absorbent my use, 8 (Lang et al., 1940). Also, American Indians granules are porous and ordinarily weigh less of high- s, were reported to have used bentonite in clean- than 30 Ib per cu ft. Because of their light ase is in “-ing blankets, and they probably dug it for other weight, size, porosity, and absorbent properties, method cleansing purposes before the Columbian the granules are suitable for many uses, and uncon. ?‘period.i;. since World War I1 many different markets for t; Lans. $ The use of fuller’s earth in the refining of oils them have developed (Fig. 2). Among other ,le beinE ;. continued to he the major one for many years. uses, they are now sold for litter and bedding and the $.The demand. for fuller’s earth for processing for poultry, pets, and other animals, and as a $hit. A =>!$ mineral oil increased rapidly in the first part of soil conditioner in greenhouses and for golf :avatirrn y this century and reached, a peak of approxi- courses. In 1982, 895,700 tons of fuller’s earth tic head Ymately 317,000 tons in 1930: this was 91.1% were sold for absorbent and filtering uses; this ning 01 5 of the total United States production that tonnage was nearly 53% of the total fuller’s inneccr. ;.,year. The production of fuller’s earth for this earth produced in the United States that year. purpose began to decrease thereafter, espe- ite werr &’L. The foregoing discussions apply only to those eum IC- k..Cially when activated bauxite was introduced in uses consuming sufficient quantities of fuller’s ~- -. 592 Industrial Minerals and Rocks be outlin the man) are prep. individua i with eac Drill in tions for gite) ful suspensic moisture Suspen sion pro] suspensia 350 cc c aged mi point Cali 600 rpm according ments ou specificat Another the filtrat ume of w when test ing ro p troleum Accordin, " .~ ..i . mud qual 1966 1967 1969 1971 1973 1975 197'7 1979 1981 -:,.-;..> ing at 60 YEAR pounds p, maximum FIG. 2-Fuller's earth sold or used by domestic producers for specified mum. P; (Ampian. 1980, 1983). .. . drilling- r ..?_..,.ii. . . r- specificati earth to be classified separately by the US the United Kingdom from sepiolite clays minZd made wit1 Bureau of Mines in the Minerals Yearbooks. in Spain. Other uses of sepiolite fuller's earth per 100 In addition, smaller quantities of fuller's earth (Chambers, 1959) are similar to those of the requiremi are or have been produced for many miscel- palygorskite (attapulgite) type mined in the P@ygorsk laneous uses. According to Oulton (1965), United, States. .,.: nies still I more than 90 different grades of fuller's earth Some reports also note that fuller's earth is Yield is a are produced. Some of these grades are used used in making cement. Probably the basis for leum lnst for pharmaceuticals designed to absorb toxins, these reports is the mining of the Twiggs Clay barrels of bacteria, and alkaloids; for treatment of dysen- Member of the Barnwell Formation near be made I tery: for purifying water and dry-cleaning Ru- Clinchfield, GA, and the use of the clay in quirement ids, dry-cleaning powders and granules: for the making portland cement. It is used for this Wet& manufacture of NCR (no carbon required) purpose mainly to obtain the desired chemical (grit test) multiple-copy paper; for the manufacture of composition in the clinker from which the C* tonite or : wallpaper: and as extenders or fillers for plastic, ment is made. The classification of this clay aS coarser tl paint, and putty. Fuller's earth mined near fuller's earth results from the fact that specified t Ellenton, FL, was used for making lightweight Twiggs Clay Member is mined for fulle1,S in 350 c, aggregate for the construction of concrete earth, and this unit is widely known in Georp agent. sti barges during World War 11 (Calver, 1957; as a source of fuller's earth, through 2. Greaves-Walker, et al., 1951). Still other uses .' . .. .:, (API STI nf fuller's earth and its suitability for uses in Product Specifications then driec new products are outlined by Haden and Product specifications have been tentativel? original t Schwint (1967), Haden (1972), and Haas standardized for bentonite and (or) fullers fulfill the (1970). One special use of fuller's earth is as earth sold for drilling mud, foundry-sand bond, have no a carrier of platinum catalysts that are made in absorbent granules, and oil bleaching and Will Palygorsk .
, .I
1 '& .*.,E .:.. >? ' : Y: Clays 593 he outlined briefly. Specifications for most of Moisrure-The maximum moisture content the many other products made from these clays of bentonite when shipped from the plant where are prepared to meet the requirements of the it is processed is 10% and that for palygorskite individual customer, and they commonly vary is 16%. with each. Foundry Sand Bond Tentative specifications Drilling Muds: The most critical specifica- for Western bentonite for bonding foundry tions for bentonite and palygorskite (attapul- sand are outlined in Steel Founders Society of gite) fuller's earth for drilling muds are the America SFSA Designation l3T-65 issued in suspension properties, wet-screen analysis, and 1965. This specification requires the following moisture as shipped. characteristics and properties for Western !. Suspension Properties-The test. for suspen- bentonite, as tested by methods described in the ' sion ..oroverties involves the ..oreoaration of a specification: (I) water content shall not ex- . suspension consisting of 22.5 g of bentonite in ceed 12% or be less than 6%; (2) pH value 350 cc of distilled water. The suspension is shall be equal to or greater than 8.2, (3) cal- aged and the viscosity determined and yield cium oxide content shall not exceed 0.70%, and ooint calculated from dial readines at 300 and (4) the liquid limit shall not be less than 600 I -, 600 rpm with a direct-indicating viscometer, or greater ihan 850. Each foundry has its own ----. ; according to procedure and equipment require- green, dry, and hot-strength specifications for ~. ments outlined in American Petroleum Institute bentonite, which vary with the type of metal, - specification API STD 13A, 5th edition, 1969. size of castings, and foundry production proce- Z Another important suspension requirement is dures. Methods of testing strengths of henton- the filtrate test, which is a measure of the vol- ite-bonded sands are outlined in detail in 1 .. : ume of water lost from the prepared suspension publications of the American Foundrymen's Ilt 2. when tested in a vressurized filter Dress accord- Society (Anon., 1962a, 1963). The tests re- :ing to procedurk outlined in American Pe- quire the preparation of a specified mixture of troleum Institute soecification API RP 13. bentonite, standard testing sand. and water: the According to these specifications, to he drilling- mud quality, a bentonite must have a dial read- .. ing at 600 rpm of 30 minimum, a yield point to controlled procidures. pounds per 100 sq ft of 3 times plastic viscosity Iron-Ore Pelletizing: Specifications for bento- maximum, and a filtrate volume of 13.5 maxi- nite used for pelletizing taconite-type iron-ore mum. Palygorskite (attapulgite) prepared for have not been standardized, and several tests drilling. mud must fulfill the same viscosity are used (Sastry and Fuerstenau, 1971; Wake- smcification as bentonite. but the susmnsion is man, 1972). As green pellets must he capable 's mined --.made~. with water containing 40 g of sait (NaCI) ~'.'ofwithstanding handling,'compaction, and dry- r's earth per 100 cc of water. Yield point and filtrate ing and the dry pellets must he even stronger, e of the requirements are not ordinarily specified for mixtures of bentonite, iron ore, and water are in the palygorskite-type drilling muds. Many compa- commonly tested for wet-drop strength, wet- .. nies still use a yield specification for bentonite. compression strength, plastic deformation, and earth is 1 Yield is a term used in earlier American Petro- dry-compression strength. basis for .''' leum Institute specifications for the number of Absorbent Granules: Most absorbent gran- ggs Clay -.-. barrels of 15 centepoise viscosity mud that can ules marketed are prepared to fulfill the require- Jn near .**5. be made from a ton of bentonite. The yield re- ments outlined in Federal Specification P-A- clay in - .. quirement is ordinarily 90 bbl per ton minimum. 1056A, Absorbent Material, Oil and Water (for for this $. , Wer-Screen Analysis-Wet-screen analysis floors and decks), outlined for purchases by the chemical (grit test) is a measure of the material in ben- US General Services Administration. A simi- e tonite or palygorskite (attapulgite) mud that is 1 the ce- "Z lar set of soecifications is outlined in the Ameri- s clay as :..coarser than ZOO-mesh US Series sieve, The that the $specified test is made by mixing 10 g bentonite fuller's e5. in 350 cc water containing 0.2 g dispersing Georgia ? agent, stirring, aging, stirring, and washing :-through a sieve with a specified spray system and absorbent characteristics required of gran- ?.(API STD 13A). The residue on the sieve is ules as outlined in the federal specification are .Ithen dried, weighed, and the percentage of the listed in Table 2. :ntativclS . original bentonite is determined. Bentonite to The specifications require that absorbent . -. , fuller's '.?fulfil the specifications for drilling mud must granules consist of a uniform mixture of min- nd bond. have no more than 2.5%' residue (grit) and erals of the silicate type. They also must be and will .:palygorskite no more than 8% residue. clean, uniform, and free of lumps or foreign ~-. 594 Industrial Minerals and Rocks ., TABLE 2-Characteristics of Ahrbent Granules ..:, .,,,-..I. - Characteristic Maximum .Minimum
Maner retained on a No. 6 US Standard Sieve 1 .O% 0.0% Maner retained on a No. 30 US Standard sieve 99.0% .52.0% .. Maner retained on a No. 40 US Standard Sieve .. 99.8% .. 73.0% Maner retained on a NO.60 US Standard sieve 100.0% 90.0% Ability to absorb lubricating oil l~ergram of sample) - 0.8 ml Ability to absorb distilled water (per gram of sample) - "'0.9rnl Solubility in distilled water 1.5% -
: matter, and no more than 10% of them can based on theoretical considerations. As the pass through an 80-mesh sieve in the attrition mineralogy of this group of clays is complex, resistance test. The attrition-resistance test is the reader is referred to authoritative books and ' ~ made by shaking with steel bdk on a screen, other references given in the introduction for : according to a specified procedure. detailed information on them, and only the . Fuller's Earfh for Bleaching Oils: Test meth- following brief summary will be given here. FIG. 3--. ods for evaluating bentonite and other types of According to the most generally accepted bentonite fuller's earths for bleaching soybean and wtton- structure, smectite consists of two silica tetra- (API sum, seed oils are outlined in the American Oil hedral sheets with a central octahedral sheet. ' E.I. Dw( Chemists Society AOCS Official Method Cc T'hc theoretical structural formula is (OH),& 8b-52, revised April 1952, and AVCS Official, ..Al,Ol,,nH,O, and the theoretical ctpposition Method Cc Sa-52, corrected 1958. These speci- without interlayer material is SO,;. 66.7%; fications contain instructions on bench-type A1,0,, 28.3%; and H,O, 5%. However, smec- tests, including stirring time, heating rates and tite always differs from the foregoing theoretical temperatures; approved equipment; quantities ..formula and composition (Table 3) because of of raw oil and clay required; methods of color substitutions of various ions for silicon in the determinations; and so forth. They also require tetrahedral coordination and for aluminum in the comparison of the material tested with an the octahedral sheet. Furthermore. the substi- official natural bleaching earth approved by the tuted ions are thought to be commonly of dif- American Oil Chemists Society. The color de- ferent valence than the theoretical ion replaced. termination of the bleached oils and their com- which results. in an unbalancing of the charge parisons with the oil bleached by the official in a unit of smectite. This charge deficiency is earth in the same test are the basis for purchase balanced by exchangeable ions. which vary con- specifications. siderably and result in further differences in the compositions of smectite. Cations which are exchangeable in bentonite include sodium, cab Geology cium, potassium, magnesium, lithium. and hy- ! drogen. The exchange capacity of most benton- that hav Mineralogy: The principal clay mineral in ite is within the range of 60 to 150 milli- ion have bentonite is smectite. according to the definition equivalents per 100 g. .. loidal pr used in this chapter, and many fuller's earth Unit layers of smectite are thought' to be dominan I deposits also consist chiefly of this mineral. The stacked with the oxygen layer of one silica other CI l term smecrite is applied as a group name, and tetrahedral sheet adjacent to the similar layer In propertif monrmorillonire is a mineral species name. the neighboring unit. Only a very weak bond valuable This usage conforms to the growing acceptance exists between neighboring units. and water 01 ing thixc of the term smectite and does away with the other polar molecules can enter between ilnlt ties usua i confusing use of montmorillonite as both layers causing the lattice to expand in the! dl- out bene mineral species and group names. Montmoril- rection. This expansion by polar molecules and other ch, lonite, including both sodium and calcium va- the collapse of expanded units with heat, which not ordii rieties. is the most common member of the can be recognized by X-ray diffraction methods. The type smectite group occurring in bentonite. How- is applied in studying smectite and distinguish- role in c ever, saponite, a magnesian smectite, and hec- ing members of this group from other clay As point torite, a lithium-bearing magnesian variety, are minerals. lonites h the major minerals in some bentonites. The ion-exchange characteristics have.an im- Propertie Smectite minerals occur in extremely small portant role in controlling or influencing the moderatf particles (Fig. 3); therefore, detailed informa- physical properties of bentonite and the bento- strength) I tion on them is difficult to obtain and is. in part. nitic fuller's earths. In general, those bentonite' hand, hi
ij ,. ,. ., .. . .-...... ~. . ... - .._ . - Clays 595
-Minimum O:O% 52.0% 73.0% 90.0% 0.8 mi ... -0.9- rnl
IS. AS the Is complex. 1 :books and duction for d only the FIG. 3-Ekcfron micrograph of given here. bentonire from Clop Spur, WY ly accepied Silic:. trtra. (API snmple 26). Micrograph by edral sheet. E.I. Dwornik, LIS Geological is iOH),Si, .~ Survey. composition 0,: -66.1%; vever, smcc- g theoretical ) because of ilicon in the iluminum in :. the substi- cionly of dii- ion replaced. If the charge deficiency i* ich vary con- :rences in the is which arc , ,. sodium, cal- ium. and hy- that have Na' as the dominant exchangeable moderate dry strengths. However, part of these most benton- ion have very high swelling capacities and col- differences in bond strengths may be due to o 150 milli- loidal properties, and those in which Ca**is the particle size or other characteristics, and there dominant ion tend to swell, little more than IS some evidence that the dry strength of some ,ought to bc other clays. Because of their high colloidal calcium bentonites can be increased by length- of one silica properties, high-swelling sodium bentonites are ening the mulling (mixing) time in the prepara- imilar layer in valuable as drilling muds and other uses requir- tion of foundry sand. 'y weak bond ing thixotropic suspensions. The calcium varie- All bentonites contain mineral impurities, and water or ties usually have little value for such uses with- which vary considerably in type and quantity between unit out beneficiation by the addition of soda ash or present. A few are contaminated with minor id in the c di- other chemicals, and even when so treated, are quantities of clay minerals other than smectite, molecules and not ordinarily as efficient as the sodium types. such as kaolinite and illite. The common non- th heat. which clay minerals in bentonite include those listed :tion methods. The type of exchangeable ion also has a major in the older definition by Ross and Shannon Id distineiiish. role in controlling the bonding characteristics. As pointed out by Grim (1962),,sodium ben- (1926). and minor quantities of most of the ,m other cla! itonites have very strong foundry sand bonding accessory minerals in volcanic rock also may properties after drying (dry strength), but only be present. Selenite is abundant in many de- cs have.an in>- . moderate strengths when moist or wet (green posits, and some beds contain carbonate veins nfluencillg tht and the bento'- strength). Calcium bentonites. on the other and concretions. Zeolite minerals and opal, cristobalite, or other forms of bentonite' nd, have high green strengths and low to poorly ordered - ~. 596 Industrial Minerals and Rocks Twiggs CIS TABLE 3-Chemical Analvsm of Clays tion (Eocei 1 2 3 4 5- 6 7 8 9 -10 Occurrei Jurassic ai SiO, 54.34 54.62 50.20 49.72 49.91 53.95 53.96 43.98 45.20 '46.77 States and 16.39 17.20 0.14 8.56 38.46 37.02 37.79 A40, 19.92 20.08 16.19 deposits m, Fe,O, 1.11 2.36 4.13 3.10 2.17 0.03 3.10 - 0.27 0.45 FeO 2.17 1.03 - 1.00 0.26 - 0.19 0.03 0.06 0.11 younger. 1 TiO, 0.11 0.11 0.20 0.58 0.24 Tr 0.24 0.01 1.26 0.02 high-swelli: CaO 0.33 0.40 2.18 4.19 2.31 0.16 2.01 0.32 0.52 0.13 duced has MgO 2.21 2.15 4.12 2.56 3.45 25.89 10.07 Tr 0.47 0.24 Na,O 2.65 2.26 0.17 0.66 0.14 3.04 0.03 0.14 0.36 0.05 age, and n 0.45 0.35 0.16 1.55 0.28 0.23 0.39 0.48 0.49 .1.49 has come f K,O - 0.01 0.04 - - - - MnO 0.01 0.01 ~ Shale. Th, - - - - Tr.-. SO, 0.18 0.16 - - - mainly in H,O- 11.73 11.78 15.58 12.21 15.77 9.29 9.79 2.58 1.55 '0.61 H,O+ 4.50 4.58 7.57 5.71 7.70 5.61 . 11.51 14.59 13.27 12.18 . . and Mioce - - - 1.71 - -. - - - -. - bentonite c co 1 p,o, - - ~- 0.06 - - - - - ' " 0.10 type, in th - - 0.73 - - - - - . -- S - .._I*< , tiary age. Ba0 ------. .------. ~. , ., :- *, California, Z"0 - - 0.03 - _' C - - - - Tr - - - - .-'. upper Tert LiO, - - - - - 1.22 - - - . 0.03 be Late Mi F ------0.24 ----- known Ch Total 99.71 99.89 100.50 100.21 99.47 99.56 99.85 100.59 100.47 -100.21- is in the B Less 0 for S 0.37 ._- ...',. ... - and deposi 99~84 also in PI] Meadows I 1. Bentonite. bluegray, clay spur bed, Belle Fourche, SO (Foster, 1953) 2. Same as 1 but Oxidized to olive green IFOSter. 19531. by Denny ~ 3. Bentonite. Polkville, MS (Ross and Hendricks. 19341. age, and if 4. Fuller's earth. Combe Hay, Somerset. United Kingdom (Kerr et SI.. 1950) are among 5. Bentonite. Chambers. AZ [Chetol (Kerr et el.. 19501. 6. Hectorite, Hector. CA (Kerr et SI.. 1950). Most be 7. Palygorskite lattapulgitel. Anapuigus. GA (Ken et ai.. 1950). bodies alii 8. Halloysite, Eureka, Utah (Ken et .I., 1950). zone. Son 9. Kaolinite. Macon, GA (Ken et el.. 1950). miles, and 10. Kaolinite. St. A~stelI,United Kingdom (Ken et .I.. 19501. ticular one diameter. - to more tt silica are present in some bentonite deposits in is also the mineral forming- meerschaum (See posits ord western United States and at several other "Meerschaum). : contact wit places in the world. Some deposits are con- Other nonbentonite fuller's earths include an one with c taminated with incompletely altered parts of the uncommon type of rock called opal claystone hydrotherfi rock from which they formed. The vitric latitic (Heron, et al., 1965). This rock is more than shaped an, tuff remaining in the bentonite at Cheto, AZ three-fourths opal or another form of poOdY directions. (Sloane and Guilbert, 1967), is an example of ordered silica, and the remainder is moot- Most be this type of material. morillonite and other mineral impurities. ]* low-swellir The principal fuller's earth deposits other was mined in South Carolina in the early Pan soaplike te than the bentonite type consist of palygorskite of this century and used for bleaching oil, and face tend (attapulgite) and sepiolite. According to Brad- it is the raw material to be mined near Rimml. when the ley (1940), palygorskite has an ideal formula SC, to supply a fuller's earth plant Under become lii of (OH,),(OH),Mg,Si,0,;4H,O, but substi- construction in 1972. Nonbentonite clays [ha' posits undt tution of AI3*for either Mg*+or Si'+ takes place. have been used as fuller's earths. in the.Pvt bluish gra: It consists of two silica chains linked in amphi- include the Anna kaolin in Illinois, halloysite In the surfac. bolelike structures and has both monoclinic and Utah (Schroter and Campbell, 1940), and Typical o orthorhombic symmetry (Christ et al.. 1969). glacial clays in Massachusetts. In additio0,t" have a poi ,Sepiolite, (Si,?) (Mg,,)0,,(OH),(OHz);6H,0, these nonbentonite clays, there are extenSIVe alternate s. deposits of fuller's earth consisting of vev is thought to have three pyroxene-type chains Outcrops I (Grim, 1968), and, therefore, the unit cell is impure montmorillonite that are not ordinardY a cracked thought of as being bentonite. .Two such de. somewhat larger than for palygorskite. Both semble all palygorskite and sepiolite typically occur in posits are the Porters Creek Clay (Paleocene) Most b, fibrous and elongate lathlike particles. Sepiolite in the Mississippi Embayment region and the ...... ~. .
Clays Twiggs Clay Member of the Barnwell Forma- where occurs in sedimentary rocks and was tion (Eocene) in Georgia. formed in place from volcanic ash or tuff. Some F deposits have been formed by hydrothermal al- 9 10 Occurrence: Though bentonite deposits of Jurassic age are extensive in western United teration of volcanic or other igneous rock. and 15.20 46.77 States and elsewhere in the world, virtually all other deposits of nearly pure smectite may be -37.02 37.19 accumulations that were transported and de- 0.27 0.45 deposits mined to date are of Cretaceous age or 0.06 0.1 1 younger. All hut a very minor tonnage of the posited in marine or alkaline lake water with 1.26 0.02 high-swelling Wyoming-type bentonite pro- only minor postdepositional alteration. 0.52 0.13 duced has been mined from beds of Cretaceous The extensive palygorskite (attapulgite) full- 0.47 0.24 0.36 0.05 age, and more than three-fourths of the total er's earth deposits in the southern part of the 0.49- 1.49 has come from a single formation-the Mowry Meigs-Attapolgus-Quincy district, Georgia and - TI- Shale. The Southern or calcium bentonite is Florida (Fig. 4), occur as tabular lenses and . mainly in formations of Cretaceous, Eocene, discontinuous beds in the Hawthorn Formation 1.55 0.61 . 13.27 - 12.18 -~ and Miocene age. .The abundant miscellaneous of Miocene age. This clay is green and bluish - - bentonite deposits, other than the high-swelling gray, and most of if has a waxy or soaplike type, in the western states are mainly of Ter- texture. tiary age. Deposits scattered through Nevada, In addition to the deposits in the United 1 California, Oregon, and Idaho are mainly in States, palygorskite fuller's earth is also mined. . upper Tertiary rocks, and many are thought to in the following regions: (1) Pout district near i be Late Miocene or Pliocene in age. The widely Mbour, Senegal (Wirth, 1968); (2) Ukrainian : known Cheto bentonite near Chambers, AZ, district, USSR (Ovcharenko et al., 1967); and .:- is in the Bidahochi Formation of Pliocene age, (3) Mudh district, India (Siddiqui, 1968). The :~ and deposits mined in western Oklahoma are Senegal deposits are in marine beds of Early I. '; '; also in Pliocene rocks. Deposits in the Ash Eocene age. The Ukrainian palygorskite is in- Meadows district, NV, occur in rocks mapped terbedded with bentonite. Deposits in India :. :. by Denny and Drewes (1965) as Pleistocene in occur between fossiliferous limestones and ap- age, and if this age assignment is correct, they parently are marine in origin. are among the youngest bentonites in the world. Insofar as the authors are aware, the only Most bentonite occurs in beds or lenticular sepiolite fuller's earth mined at the time this bodies aligned along a definite stratigraphic report was written is in the Vallecas and an- zone. Some beds extend for more than 200 other district in Spain (Anon., 1972b). How- . miles, and other deposits, particularly the len- ever, economic sepiolite deposits have been dis- ticular ones, are only a few hundred yards in covered recently in the Ash Meadows district, - diameter. Deposits mined range from about 1 Nevada (private communication). The Spanish to.more than 30 ft in thickness. Bedded de- deposits occur in an evaporite sequence .of Ter- Eerschaum (see posits ordinarily have a characteristic sharp tiary age.. The Nevada deposits are closely as- -. contact with underlying rocks and a gradational sociated with calcium, sodium, and magnesium inhs include an . one with overlying strata. Deposits formed by bentonites of Pleistocene age. opal claystonc hydrothermal processes tend to be irregularly Origin: The evidence for most bedded bento- :k is more than - shaped and to grade into the host rock in all nite having formed from volcanic materials directions. form of poorly ,& transported considerable distances in the atmo- inder is mont- ?-c-- Most bentonite, including both the high and sphere was presen!ed by several geologists early impurities. I! 7- low-swelling types, has a characteristic waxy or in the century, including Hewett (1917), n the early pan .: soaplike texture. Pans of deposits near the sur- Wherry (19171, and recently by Slaughter and :aching oil, and - face tend to be light-yellowish green or gray Earley (1965). This conclusion is based pri- ed near Rimini. .. when the natural moisture is present and to marily on the purity of smectite, on the fact that th plant under -become lighter in color when they dry. De- the nonclay minerals in bentonite are angular :onite clays thnl . posits under Considerable overburden tend to be and of the type occurring in volcanic rock, ths in the PSI ., bluish gray. The change to lighter shades near rather than mixtures of rounded grains charac- ois, halloysite in z. the surface is related to the oxidation of iron. teristic of detrital sediments, and on the pres- :II, 1940), and Z Typical outcrops of high-swelling bentonite ence of relict shard textures in many bentonites ?= In addition to - have a popcornlike or frothy texture caused by (Ross and Shannon, 1926). Ample evidence e are extensive _-galternate swelling and drying of the bentonite. supports the conclusion that the parent ash of lsisting of veF &Outcrops of low-swelling types commonly have most bentonite was deposited under marine .e.not ordinarily ,:.sa cracked appearance thought by some to re- conditions, but a few deposits apparently ac- Two -such de semble alligator hide. cumulated in alkaline lakes (Papke, 1969). As lay (Paleocene) Most bentonite in North America and else- would be expected, different bentonites have region and the have smect tion o by w rocks, ties, i plied (Sidd bayev (Papk posits Rober from mass. nonigt AS they h er's ea tite an paha in Ge< ably fg have t miner: eviden been F these palygo water This t! forma:
,. ~ Distrit formed from volcanic rock of somewhat dif- occurs in Nevada (Papke, 1969). California .. ferent types, and the most common parent ma- (Kelley, 1966), Spain (Anon., 1972b), ad Nor terials range from andesite to rhyolite in com- elsewhere. Deposits of this type commonly are BENTC position. Opinions differ concerning the process associated with other minerals known to have calciiii and time of alteration of the ash. Several au- formed by hydrothermal processes. They also sissipp thors have noted that change in ash would have tend to occur in irregularly shaped bodies ra- YTeagi begun with its contact with water, hut when the ther than in beds, and they ordinarily grade into -posits alteration was completed is questionable. Papke the host rock through partially altered zones. and 1, (1969) believes that one type of bentonite de- The distribution and shape of bentonite formed differe posit formed in alkaline lakes soon after deposi- hydrothermally are commonly controlled by .and 11 j tion and another type formed more slowly as fault zones, joints, and other geologic features these 1 the result of alteration by ground water. Altera- providing access for heated water, .. sippi, I i tion by ground water requires burial by younger , .. Alteration of volcanic ash or tuff in restricted The rocks and probably regional uplift and con- ! a alkaline lakes heated by hot-spring activity is mainl) ! siderable interval of geologic time. In the au- also thought to have formed bentonite .(Arne? region thors' opinion, changes have taken place in et ai., 1958). The hectorite deposits in Cab rangin i bentonite deposits throughout virtually their en. fornia probably formed this way, and this clay cene , tire geologic history. Some deposits may have passed through an intermediate stage in which et ai., been altered extensively before burial beneath most of the.ash was altered to zeolite. A mag mitten younger rocks. However, the prominent cherty nesium bentonite called amargosite formerly LA (C zone below several beds points to the downward mined near Shoshone, CA, also formed by mined transport of silica by ground water from alter- the alteration of vitric volcanic material.by hot which ing deposits; this must have taken place after springs (Sbeppard and Gude, 1968). The V' burial. Though the authors have doubts about the Forma Bentonite formed by hydrothermal activity theory. some bentonite deposits are thought 10 tonite ,. , .
Clays , . 599 have been deposited mainly in the form of duced in Mississippi is mined near Aberdeen, smectite minerals. According to this explana- Monroe County, where the American Colloid tion of origin, smectite minerals, having formed and International Minerals & Chemical Corps. by weathering of volcanic or other igneous operate plants. Bentonite is also mined inter- rocks, were transported, separated from impuri- mittently in Smith County, and clay that is pre- ties, and deposited. This theory has been ap- sumably bentonite is produced in Pearl River plied to explain the origin of deposits in India County. The deposits mined in Monroe County (Siddique and Bahl, 1965), the USSR (Tazbi- are in the Eutaw Formation of Late Cretaceous bayeva and Galiyev, 19721, and Nevada age. Deposits mined in Smith County are in (Papke, 1969). Bentonitic fuller’s earth de- Oligocene rocks, and the deposits in Pearl River posits in the United Kingdom were thought by County are of Miocene age (Bicker, 1970). The Robertson (1961) to have been transported bentonite processed near Sandy Ridge, AL, oc- from smectite-rich soils on the European land- curs in the Ripley Formation [Upper Creta- mass. Such soil woutd have formed mainly on ceous] (Monroe, 1941). nonigneous rocks. Fuller’s earth is produced mainly in the As most fuller’s earth deposits are bentonites, southern states; and the Meigs-Attapulgus- they have the same origins; however, some full- Quincy district, Georgia and Florida (Fig. 4), er’s earths consist of minerals other than smec- is the leading fuller’s earth-producing district in tite and may he of quite different origin. The the United States. The deposits mined in this palygorskite (attapulgite) fuller’s earth deposits district occur in the Hawthorn Formation of .. in Georgia and Florida are one type that prob- Miocene age. Those in the northern part of the ably formed in a different way. These deposits district consist chiefly of diatomaceous mont- have been investigated by several geologists and morillonite containing minor quantities of other mineralogists, and no one has found convincing clay minerals and clastic nonclay mineral im- evidence of any volcanic materials having ever purities. Some of the deposits in the southern been present. The first author has investigated part of the district are the purest palygorskite these deposits in detail and believes that the (attapulgite) mined in the world. The fuller’s palygorskite in them formed in place from sea- earth mined in central Peninsular Florida also water evaporating in a.tidal-flat environment. occurs in the Hawthorn Formation, and this This theory is essentially the same as the “neo- clay consists chiefly of montmorillonite. formation” idea of Millot (1964). ’ F. Large deposits of fuller’s earth occur in the Twiggs Clay member of the Barnwell Forma- ’ Distribution of Deposits tion of Eocene age. These deposits crop out in California a belt extending across central Georgia seaward >72b), and ’ North America: United States-SOUTHERN BENTONITEAND FULLER’SEARTH-Southern or, from the fall line. The Twiggs Clay member is nmonly are now mined and process ._ L". ~. i' Clays 601 Cali. posits in Kern County, bentonite near Olancha earth resources is in the extensive Porters Creek min. and probably deposits at other localities in Cali- Clay and the Twiggs Clay Member of the Barn- ad. fornia have been processed for filtering and well Formation. These deposits are suitable for 'Port . decolorizing agents in recent years, use in absorbent granules and certain other RESouncEs-Resources of bentonite and full. fuller's earth products, but they are not used %osa er's earth in the United States are very large. in drilling mud and several of the speciality ;h of The reserves of bentonite are at least one billion products. A2 tons, and the total resources, including all ben- Canada-Bentonite occurs in beds of Cre- the tonite that will be eventually suitable for one taceous and Tertiary ages at many places in and use or another, are considerably larger. This western Canada (Ross, 1964; Spence, 1924). Con. reserve estimate of one billion tons includes The major producing districts (Fig. 5) are very large deposits that have a quality buitable Onoway (Baroid Canada, Lid.) and Rosalind -Ben. for binding iron-ore pellets but that would be (Dresser Industries, Inc.) in Alberta and in the hec. 1 classed as submarginal for 'drilling .mud and Pembina district (Pembina Mountain Clays, tered several speciality uses. The reserves of very Lid.) in Manitoba. Bentonite has also been gen. . high quality drilling-mud bentonite are limited mined near Princeton, B.C., and deposits near losits ". and are much in demand. Resources of fuller's Avonlea, Sask. (Anon., 1971), and along the n the ; earth are tentatively estimated at two billion Mackenzie River in the vicinity of Inuvik. G-uf ., tans. However, almost any figure could be used N.W.T., have been investigated by industry. ihem - here, if all the clays equal in quality to the low- The deposits mined in Alberta are in the nen. : est grade material used as bleaching clay in the Edmonton formation, the uppermost Creta- lined past~- were included. A large part of the fuller's ceous unit in this region. Those mined at Rosa- :y Of der. C'"' C'"' lesic- jtocl (hein ?osiis ation jome used ento- :d of ,ively i the iped- 1g or pro- 1g or ento- .hem 3orn pri- : dir- unq. re 11 hlar- pro. le of ;hale mite. this icidc , are de- FIG. 5-Map showing bentonite districts in Canada. I- 602 Industrial Minerals and Rocks lind are nearly flat lying and are 8 to 10 ft thick. A few thousand tons of fuller's earth are also 1 ( The deposits mined at Onoway are 2 to 2Y2 ft produced each year. The fuller's earth deposits I thick, and the overburden removed from them mined are in La Rioja and Rio Negro provinces. 1 has an average thickness of about 7 ft. Benton- Brazil-A plant processing montmorillonite : il ite deposits mined in the Pemhina district are clays for use as foundry-sand bond was-built ; t8 in the Vermillion River formation (Upper Cre- at Sacramento, Minas Gerais, in 1962 (Anon,, 7 li taceous), which consists mainly of black shale. 1962). Bentonite has also been found at sev. . F The bentonite near Princeton. B.C., is of Ter- era1 other localities in the country. --., L. d tiary age, and it is interbedded with lignite Peru-Bentonite and fuller's earth occur io f d (Spence, 1924). the provinces of Pisco, Canete, Paita, and Con- ' a Several grades of bentonite are produced in tralmirante Villar, and elsewhere (Caherra, Canada. The swelling bentonite mined in Al- 1963). Bentonite has been mined and usetin it berta is sold for use in drilling mud, foundry. iron-ore pelletizing- in Peru for several years P sand bond, fire retardant, and stock-feed pel- (Anon., 1967a), and present production is cs- ,~ P letizing (Ross, 1964). The bentonite produced timated to be 20,000 tpy (Anon., 1973a). ~- -2 a in the Pembina Valley is a low or nonswelling Europe: Cyprus-A low-swelling calcium variety. It is processed in a plant at Morden, bentonite is mined in the Troulli district near C: Man., and some is activated with sulfuric acid Kambia (Anon., 19691). A few thousand tons ~ P in a plant at Winnipeg. This bentonite is used are produced annually. Part is processed in a U for foundry-sand bond, insecticide carriers, and small plant at Vassiliko, and part is shipped to . ti pelletizing animal feed. The activated bentonite Israel for heneficiation and use in several prod- is used for bleaching mineral lubricating oils . (: ucts (Anon., 1970e). P and waxes, re-refining used lubricating oils, gnd Czechoslovakia-Bentonite. occurs in ~ the 01 decolorizing animal and vegetable oils. northwestern, central, and eastern parts of : ai According to Ross (1964), only a very few Czechoslovakia (Gregor, 1967). The bentonite fc million tons of bentonite reserves have been is chiefly of the calcium and magnesium types, proved in Canada. However, the potential re- and it formed from rhyolite tuffs. It is as much bi sources of bentonite in the country must be as 70% montmorillonite; the nonclay minerals 01 very large, considering the large areas now present include cristobalite. Bentonite reserves known to contain Fcattered deposits and the ar in Czechoslovakia were estimated to be IO mil- , C general similarities of strata to Cretaceous and lion tons. Tertiary rocks in the United States known to W Apparently, the most productive bentonite .rt contain bentonite. district is in the northwestern part of the coun- j Mexico-The German firm Siid-Chemie AG th try, inasmuch as a bentonite processing plant 2. with its Mexican affiliate Tonsil Mexicana SA having a yearly capacity of 100,000 .tons was has operated a bentonite plant in Puebla since (/ built at Zelenice (Anon., 19691). One-third-of ar 1967 (Anon., 1969k), and another plant is ac- the bentonite produced in this plant is reported , co tive intermittently at Monterrey. Bentonite and to be available for export. .. fo fuller's earth also occur in QuerCtaro, Michoa- France-The company SociCtC Fransabe des -of ch. and Guanajuato, and a few of these de- Bentonites Dkrives SarL. markets several et St posits have been mined on a small scale (Es- grades of bentonite. mined principally in cen- quivel and Zamora, 1958). Apparently, most tral France (Anon., 39691). The deposits mined Mexican bentonite deposits occur in sedimen- are presumably those in the Department of dL tary rocks, and some of these are of the non- Vienne and the Limousin region that have been pa marine type. worked for many years (DCribCre and Esme. (V South America: Argenrino-Bentonite de- 1943). Other bentonite and fuller's earth de- in! posits are scattered throughout several prov- posits are in Vaucluse (Mormoiron, Sainte- an inces in Argentina (Bordas, 1947). The princi- Radegonde. and Apt) and PyrCnCes. Most pe pal deposits mined and the 1969 production bentonite and fuller's earth-deposits in France tre (Anon., 1971b) are as follows: are chiefly smectite, hut those at Mormoiron Tt are mixtures of smectite and palygorskite-(Mil- (P Tons ite Principal Deposits Province Produced lot, 1964). Greece-Rather extensive deposits of benton- m: Rio Chico Chubut 5.286 ite occur in the eastern part of the island Of tie El Alamo y Las Hegueras Mendoza 19.799 Milos (Anon.. 19691). The deposits are as de El Catalin Neuquen 4,622 much as 100 ft thick. Apparently they formed NI Del Lag0 Camino y Rob Rio Negro 14,427 by the alteration of ash or tuffs of Pliocene age in La Emilia y Cristina San Juan 18,005 in a marine environment (Wetzenstein, 1972). un Total 62.139 One plant near deep water operated by the fl0 .- . ,, ,, . . ._,.: . . ..._.. I Cla)IS 603 r's earth are also Greek company, Silver and Barytes Ores Min- ing muds in countries bordering the Mediter- .r's earth deposits ing Co., has a yearly capacity of 200,000 tons. ranean Sea and in the Near East. Negro provinces, Three other companies are also mining benton- Poland-Bentonite deposits of Eocene and montmorillonite ite on this island (Wayland, 1971). .The ben- Miocene age occur in southern Poland: these I bond was built tonite producers on Milos have been particu- are processed for use as bleaching clay (No- in 1962 (Anon., larly successful in selling bentonite for iron-ore wacki and Ciechomska, 1964) and probably for :en found at sev. pelletizing, mainly because of the nearness of other uses. .intry. deposits to deep-water shipping. Bentonite pro- Romania-Romania has been one of the ma- .'s earth occur in duced on this island is also sold for drilling mud jor East European bentonite-producing coun- :, Paita, and Con. and foundry-sand bond, and for other purposes. tries for several years. The bentonite is mined .where (Caberra, . In addition to the deposits on Milos, benton- underground in the Alba-lulia-Ocana Mures lined and used in , ite also occurs on Mikonos where three com- district (Neacyu, 1969), and apparently it is for several years panies have been active in recent years. With produced elsewhere. The yearly production of production is es. production on both islands, Greece ranks bentonite in Romania is estimated to be more on., 1973a). .. among the leading producers of bentonite. than 100,000 tons (Huvos and Sondermayer, swelling calcium = Hungary-Bentonite occurs at scattered lo- 1968). oulli district near - calities in Hungary. Recently, bentonite- Spain-Bentonite and fuller's earth occur at ew thousand tons' processing facilities were concentrated at Mod, several places in Spain. The most productive is processed in a under the supervision of personnel of the Na- bentonite deposits are in the Cab0 de Gata re- part is shipped to ' tional Ore and Mineral Mining Enterprise gion in Almeria. These deposits have formed e in several prod- (Sondermayer, 1967). The new plant is re- by the hydrothermal alteration of rhyolite and ported to have a capacity for processing 100,- andesite igneous rocks (Anon., 1972b; Martin occurs in the . 000 tpy of raw bentonite. Both natural calcium Vivaldi and Linares, 1968, 1969). The more eastern parts of and sodium-exchanged bentonites are produced intensely altered parts of deposits contain 1). The bentonite ' for several different uses (Anon., 1970d). kaolinite, alunite, and jarosite. Other parts s magnesium types, I Italy-Italy is one of the leading European contain minor amounts of palygorskite and lffs. It is as much bentonite producers. The deposits. mined are sepiolite, which presumably indicates an excess nonclay minerals on the island of Ponza, offthe western coast, of magnesium at the time of alteration. Fuller's jentonite reserves and on Sardinia. The Ponza deposits are near earth deposits consisting mainly of sepiolite Ited to be 10 mil- Cala dell Acqua. They are in volcanic rock and occur at Vallecas and elsewhere in the Tagus .. were formed by hydrothermal alteration of basin (Anon., 1972b; Huertas, et al., 1971). iuctive bentonite rhyolite tuffs (Lupino, 1954). The average The deposits are in an evaporite sequence of part of the coun- thickness of these deposits is about 10 m, and Tertiary age. The annual output of fuller's processing plant 2.9 million tons is estimated to be present earth in the Vallecas district is approximately 100,000 tons was . '(Anon., 1969i). Several grades of beqtoqite 14 kt. Absorbent granules, insecticide car- 21). One-third of are produced on Ponza, and one of them is a riers, and material5 for other uses are produced. plant is reported colloidal white bentonite that brings a high price Switzerland-Bentonite is mined in Switzer- for speciality uses. This white bentonite is one land and used in bonding foundry sands (Grim, iet6 Franqaise des of the few bentonites imported hy the United 1962). markets several States. Unired Kingdom-Calcium montmorillonite clays occur at many places rincipally in cen- The deposits on Sardinia are mined by In- in the United King. he deposits mined dustria Chimca Laviosa SPA, an Italian com- dom, and fuller's earth has been mined since the : Department of pany (Anon.. 1970b), and NL Industries, Inc. Roman period nearly 2000 years ago (Anon., - 1969f). Fuller's earth districts now active are 3n that have been (Wayland, 1971). The Italian company is min- at Redhill Surrey, Combe Hay south Bath -ibire and Esme. ing the Pedra de Fogu deposits near Alghero. in of . in Somerset, and Woburn in Bedfordshire. In fuller's earth de- and grades suitable for drilling mud, iron-ore ,rmoiron, Sainte- addition to these districts, large deposits of cal- i pelletizing. civil engineering applications, water cium montmorillonite have been discovered in Pyrenies. Most : treatment, and wine purification are produced. eposits in France the Swindon-Abington district in Berkshire by 5.. The deposits mined occur in altered rocks ,e at Mormoiron the Institute of Geological Sciences (Poole and (Pietracaprina and Novelli, 1972). The benton- lalygorskite (Mil- Kelk, 1971; Poole et al., 1971), and other de- L. ite mined is the swelling type. It is approxi- posits occur near Clophill in Bedfordshire, and :posits of benton- k mately 70% montmorillonite. and the impuri- Maidstone in Kent. of the island of .ties are chiefly free silica, illite, and calcite. The The deposits in Surrey and Bedfordshire are deposits are as deposits mined by NL Industries are near in the Lower Greensand, which is the upper ,ntly they formed - Nurallao (Anon., 1969g). These deposits are formation of the Lower Cretaceous Series 'S of Pliocene age in Miocene marine sediments. and they are (Holmes, 1950). These deposits consist of ,tzenstein, 1972). it underlain by Jurassic limestone and trachyte hard bluish-gray clay having a soapy feel. They operated by the 3, flows. This bentonite is sold primarily for drill- are in beds of-imegular thicknesses, and at I 604 ~-. Industrial Miner,ais and Rocks .. 3 places as many as eight beds of clay are present rine environment. However, some deposits my converted intc in the Lower Greensand.. Thicknesses of clay have been altered from other rocks by hydro- : Bentomak pla mined range from 5 to 8 ft. Most mining is by thermal solutions. . .~.-. .. stripping methods, but deposits in the Combe Africa: AI{ The scattered bentonite deposits in Kazakh- mined in the I Hay district are mined underground. stan occur mainly in Lower Tertiary rocks .: of Algeria (AI The fuller's earth at Combe Hay district oc- (Akhmed, 1963; Tazhibayeva and Galiyev. curs in the Great Oolite series of Middle Juras- production in 1972). They are thought to have altered from - 25,000 to 38 sic age. These fuller's earth deposits are com- hydromica and related minerals in an alkaline processed in ~ monly 6 to 7 ft thick. As in several bentonite and deoxydizing environment in inland seas in shipped across deposits in the United States, the fresh clay in regions of arid climate. The mica minerals ap the Combe Hay district is bluish green, and the parently were transported from weathered rocks at Oudja. weathered parts of the deposits are yellowish. in land areas. . ., The bentoni !.. in both altere< ' Fuller's earth production in the United King- The principal uses of bentonite in USSR are dom has quadrupled since 1945, and 176,000 sedimentary r( in the manufacture of heavy clay products, .: dran, et al., I! tons was produced in 1970 (Anon., 1972~). drilling mud, and iron-ore pelletizing, and mi- essentially pur Probably the biggest market is for foundry-sand nor quantities are used in purifying oils, water, " the deposits all bond, and some of the clay is treated with soda and wine. In 1967 about 1.5 million tons was ash for this use. Sodium-exchanged fuller's traces of kaolii produced (Lebedinskii and Kirichenko, 1972). deposits are I( earth is also used in pelletizing animal feeds, and the total consumption was about 3.4 million' treating domestic water supplies, and for sev- tons. Imports to fulfill requirements came from --; Kenya-Ber eral uses requiring swelling or thixotropic prop- Italy, Czechoslovakia, and Hungary. has been mil foundry-sand I erties, including civil engineering uses, drilling ._-W.esf Germany-Lower Bavaria has bgen a mud, and for water-impeding purposes. Ap- major. producer of smectitic fuller's earth"and . Malagasy-! proximately a fifth of the fuller's earth pro- bentonite for many years. The two major pro- scale in this co duced is acid activated; this clay is sold mainly ducers are Siid Cbemie AG, which has a plmt reported to ha\ tryin 1969 (AI for alkylation catalysts. at Mooseberg (Anon., 1969k), and Erbsloh and USSR-The principal bentonite deposits in Co., which operates a plant at Landshut (Anon., Morocco- F the USSR are in the Volga Region, western and 1969e). The deposits are mined mainly by occur in the C central parts of the Ukraine, Transcaucasia Re- open-pit methods, but some underground min- localities near gion, Kazakhstan, and Central Asia (Lebedin- ing is still done. Both companies produce This bentonite skii and Kirichenko, 1972; Anon., 1970a). sodium-exchanged bentonite for use in foundry- mation of the Smaller bentonite resources also occur in east- sand bonding and for use in several products It occurs in b ern and western Siberia, Crimea, and 'in the requiring colloidal properties. Smectite clays lagoonal or lac northern Caucasus. are also acid activated and exported to several Production in Several large bentonite deposits of Lower countries for processing oils and waxes. .20,000 to 30,O Miocene age occur in the Cherkassy district Yugoslavia-CaIcium-type bentonite ,occurs ' Another ty1 (Ovcharenko et al., 1967), which is located in many places in Yugoslavia, and the total magnesium m along the border between the Cherkassy and resources in the country are very large (Anon.. (rhassoul in FI Kiev regions in the Ukraine. The deposits 1969111). The bentonite is processed, including in the Tamdafc consist of five layers having maximum thick- some sodium exchanging, at several places. The valley (Jeanne! nesses ranging from 1.5 to 8 m. Though most three largest producers have a total annual plant sold for severa of this bentonite consists chiefly of montmorillo- capacity of 100,000 tons, of which 30,000 can Ghassoul is a t nite containing minor quantities of detrital min- be acid-activated. Yugoslavia exports bentonite lonite containi: eral impurities, one layer as much as 2 m thick mainly to East European countries, but minor in five separate is mainly palygorskite (attapulgite). This paly- tonnages are also shipped to West European IS to 80 cm. gorskite was discovered during geological stud- markets. The quantity exported in 1968 Was Mozambiqu< ies in 1954, and it is the first fuller's earth de- 23,745 tons. near Impampv posit of this composition found in sufficient The best quality bentonite in Yugoslavia is in . 26 tpd began p quantities for mining in Russia. the Ginovci deposits, 81 km northeast of Skople bentonite also Most bentonite produced in Azerbaijan in the (Konta, et al., 1971). These deposits are m Marques in IC Transcaucasia Region is mined from beds of lacustrine beds of late Pliocene age, and they marketed in Et Cretaceous age (Seidov and Alizade, 1966), but formed by alteration of dacite tuffs. The hen- Senegnl-La younger deposits are also present in this region. tonite is reported to be more than 85% smec- ing principally The bentonite in Azerbaijan is interbedded with tite and contains 1.2% quartz and 0.5% Cns- CUI in the Pout ~ tuff and calcareous sedimentary rocks and is tobalite. Reserves of the three best grades of (Wirth, 1968) thought to have formed mainly by the decom- bentonite in these deposits are estimated to p" cene sediment; position and alteration of volcanic ash in a ma- 1.4 million tons. The Ginovci bentonite 1s cording to the in Senegal are .. .: . , . .. ,. . ;.-.:_ . . . 'I - Clays 605 deposits may converted into a'sodium type in the modern best fuller's earth mined in the United States, by hydro. Bentomak plant near Kriva Palanka. but they are used for several of the same prod- Africa: Algeria-Calcium-type bentonite is ucts. Most of the fuller's earth produced in the i in Kazakh. mined in the Marnia and Mostaganem districts Pout region is shipped to European markets. :rtiary rocks of Algeria (Anon., 19691). Algerian bentonite South Africa-Bentonite is mined in Trans- .nd Galiyev, production in recent years has ranged from vaal and Orange Free State, and it is reported altered from 25,000 to 38,000 tpy. Part of this clay is to have been discovered near Plettenberg Bay, .I an alkaline processed in a plant at Marnia, and part is Cape Province (Anon., 1972j; Woodmansee dand seas in shipped across the Moroccan border to a plant and Murchison, 1969). Production has in- minerals ap. at Oudja. creased in recent years and now virtually all of Athered rocks The bentonite in the Marnia district occurs South Africa's bentonite requirements are ful- in both altered rhyolite masses and as beds in filled by the domestic output. Apparently, the in USSR are sedimentary rock of Lower Miocene age (Sa- deposits mined consist chiefly of smectite min- aY Products. dran, et al., 1955). Much of this bentonite is erals. The authors are unaware of any develop- :in& and mi. essentially pure montmorillonite, but some of ment of the palygorskite (attapulgite) deposits g oils, water, the deposits altered from volcanic rock contain at Springbok Flats that are widely referred to jion tons was traces of kaolinite and some of the transported in the geologic literature. enko, 1972). deposits are 10 to 20% kaolinite. Tanganyika-The production of a few tons ut34million Kenya-Bentonite in the Athi River valley of bentonite in Tanganyika in 1958 was re- ts came from has been mined intermittently for use as ported by Ross (I 964). Y. foundry-sand bonding (Thompson, 1952). TanzaniaSlatick (1969) noted the produc- a has been a ' Malagasy-Bentonite is produced on a small tion of 203 tons of bentonite in Tanzania and 1's earth and scale in this country, inasmuch as 99 tons were small quantities mined in other years. major pro. '0 reported to have been exported from that coun- Asia: India-Major fuller's earth deposits h has a plant try in 1969 (Anon., 1969~). occur in at least five states in India, and benton- I Erbslah and Morocco-Extensive deposits of bentonite ite occurs at several localities. Probably the lshut (Anon., occur in the Camp Berteaux district and other best known deposits are in the Barmer district, d mainly by localities near Taourirt in eastern Morocco. Rajasthan (Siddique and Bahl, 1965). They rground min- This bentonite is the product of the transfor- are believed to be transported clays deposited nies produce mation of the glassy materials in volcanic ash. in a marine embayment during late Tertiary ;e in foundry- It occurs in beds interstratified with Miocene time, and the clay minerals formed by the era1 products lagoonal or lacustrine deposits (Millot. 1964). weathering of igneous rock. Other deposits mectite clays Production in recent years has ranged from occur in Tertiary beds in Gujarat and in Mio- :ed to several . 20,000 to 30,000 tpy (Anon., 19691). cene rocks in Jammu and Kashmir; those in 'axes. Madras and Bihar are of Jurassic age. Fuller's tonite occurs i Another type of clay consisting mainlysf .. magnesium montmorillonite called ghnrsoul earth mined in the Mudh district is of Eocene ind the total (rhassoul in French) is produced from deposits age, and it is chiefly palygorskite (Siddiqui, large (Anon.. : in the Tamdafelt district in the middle Moulaya 1968). Indian bentonite is used for drilling ;ed, including valley (Jeannette, 1952; Eyssautier, 1952) and mud, foundry-sand bonding, water sealant, and 11 places. The sold for several uses requiring absorbent clay. other uses. The deposits in Gujarat are near ~ annual plant Ghassoul is a brown to black waxy montmoril- the coast,'and some of this bentonite is sold in can h 30,000 lonite containing 26 to 28% MgO. It occurs Europe and elsewhere. Apparently most of the xis bentonite i . . in five separate beds ranging in thickness from fuller's earth produced is used domestically for :s, but minor I I5 to 80 cm. purifying oils and processing fibers. :st European Japan-Two rather distinct types of smectite in 1968 was Mozambique-A bentonite processing plant near lmpamputo having a capacity of 24 to mineral deposits occur in Japan (Takeshi and 26 tpd began production in 1963. High-quality Kato, 1969); one is called bentonite and the lgoslavia is in : ' bentonite also has been produced at LnurenGo other, acid clay. The bentonite is composed :ast of Skopje ' Marques in recent years, and some of it, is chiefly of sodium montmorillonite, and the acid posits are in marketed in Europe (Anon., 1973a). clay is montmorillonite in which H- has substi- Ige, and they Senegal-Large fuller's earth deposits consist- tuted for exchangeable Mpand Ca++. Deposits Ts. The ben- of both types occur at several places in Japan. 85% smec- ing principally of palygonkite (attapulgite) oc- cur in the Pout region and elsewhere in Senegal Bentonite altered from bedded rocks called d 0.5% CnS- (Wirth, 1968). The deposits are in lower Eo- Green Tuff of Miocene age occur in Hok- est grades of :. ~cenesedimentary beds of marine origin. Ac- kaido and several places in Honshu (Takeshi iimated to be cording to the published test data, the deposits and Kato, 1969; Urasima, Syoya, and Suzaki, bentonite is 'r. i in Senegal.are not as high grade as some of the 1966). Large deposits formed by hydrothermal - ~-.~ Industrial Minerals and Rocks ... .-,.. alteration of rhyolite and rhyolitic tuffs occur in Co. operates a bentonite plant in Seoul (Anon., ‘j minerals, re Higashikambara-gun district, Niigata Prefecture 1973a). The mines are located in North .- - geologic occ (Takeshi, 1963). The Teikoku deposit, one of Kyongsang Province. ‘j testing, and several in this district, is principally sodium Turkey-Bentonite and fuller’s earth occu.r-at standing of montmorillonite. Bentonite formed by diagenic several places in Turkey. Bentonite has been tial in the I alteration of tuff beds occurs at Usui-gun, produced on a small scale for domestic use as reviewing al Gunma Prefecture, and several places in Yama- foundry-sand bond, wine purification, insecti- on deposits i gata Prefecture (Takeshi and Kato, 1969: cide carriers, and other uses for several years. rocks in the Omori, et al., 1961). Several of these deposits In 1973, plans were underway for expansion of field investig - contain appreciable quantities of zeolite, cris- mining and processing of sodium bentonite but reconna tobalite, and detrital minerals, which contami- (Anon., 1973). Fuller’s earth presumably has for many d nate the montmorillonite. been used locally for centuries. beds are ger Large deposits of acid clay formed by dia- The older productive deposits apparently are cause of the genic processes occnr at Tsuruoka-shi district, at Killik, Eskisehir Province, and Kursunlu and to develop a Yamagata Prefecture, at Kitakanbara-gun, Nii- KWk, Cankiri Province (Anon., 196.5). The by shrinkagc gata Prefecture, and elsewhere. Acid clay sodium bentonite is near Resadiye, Tokat swelling ben formed hydrothermally also occurs at several (Anon., 1973). posits are no places in Niigata. Oceania: Ausfralia-A few hundred tons of bentonite, ai The yearly bentonite production in Japan is bentonite have been produced in Australia in required. estimated to be approximately 300,000 tons, recent years (Kalix, 1971), and there has been Once loca and demands are increasing (Takeshi and Kato, intermittent mining of fuller’s earth for a long ing or drilli 1969). Several companies are now active and ria. The bentonite produced in 1970, ihe last widely used are processing bentonite in different ways for year for which figures are available, was 136 overlying rc domestic markets and export. Japanese henton- tons from Nanango Mineral Field and 100 tons equipment a ite is used for foundry-sand bond. drilling from Ipswich in Queensland, and 116 tons from torily, partic mud, several pelletizing and briquetting bond lake deposits at Marahagee and Woodanilling in the top of uses, agricultural engineering, soil-improving the southwestern part of Western Australia. In augers are a agent, additives for ceramic raw materials, car- that year, 58,244 tons of bentonite was im- ploration, bt riers for agricultural chemicals, paper making, ported from the United States, and the average to be unsatii .filler for water-based paint, clarifying and coag- f.0.b. value was $23.08 per ton. Considerable skite (attapu ulation liquids, making organic-clad bentonite, interest in bentonite in Australia has developed are common1 and for other uses. Acid clay is used mainly to because of its possible use in pelletizing iron and a fishtai produce activated clay by a sulfuric acid-treat- ore and other uses, and it seems likely that sandy overb ment process. Aluminum sulfate and synthetic valuable deposits will be found. Fuller’s earth with water. gypsum, made with the addition of calcium, are was mined on a small scale in the Dubbo dis- .i ting head is recovered as byproducts of this process. The trict, New South Wales, as recently as 1969. approached, activated clay is used in decolorizing lubricating New Zealand-Bentonite mining began in equipment. oils and other oils and fats, for hygroscopic and New Zealand at Porangahau, Hawke’s Bay, In found to be absorptive applications, and as petroleum cata- 1940, and in recent years it has also been pro- plete recover lyst. Acid clay is also used in the manufacture duced in the Harper Hills region of Canterbury. also used in of globular alumina gel, silica gel, fine powdery The Harper Hills deposits mined are in lower hard rock in silica, filler for noncarbon duplicating paper, Eocene beds, and apparently they formed by the Testing: T alteration of volcanic materials deposited in a and for other uses. The exported Japanese earth is han6 marine environment (Ritchie, et al., 1969). bentonite and acid clay are shipped primarily universally a Bentonite also occurs in beds of Miocene and to countries in southeastern Asia, and petroleum tioos. As a probable Late Cretaceous ages catalysts are apparently the principal products in this region. their valuabl: The bentonite mined in the Harper Hills regton shioned...~~ different way is a tow-swelling iron-rich variety, Eontainlng Pakistan-Bentonite occurs at several places the widely as much as 10% kaolinitic clay. New Zealand Y. in Pakistan. Deposits in the Bhimber district of the many d. Azad Kashmir of probable middle Pliocene age bentonite is used mainly for foundry-sand bond and as an additive to ceramic material, but It purchasers f< have been mined since 1958 (Ali and Shahn. single grade 1962). The bentonite is used for several pur- may be suitable for other uses, including Pel- letizing taconite iron ore. Slurry of dit poses, including the preparation of surgical procedures, dressings. A plant for processing activated Evaluation of Deposits and even m, bentonite at the rate of 20 tpd was under con- limits. Clear struction at Gujrat in 1962 (Nawaz, 1962). Exploration: The exploration for bentonite procedures i: South Korea-The Dong Bo Clay Industrial and fuller’s earth deposits, as for virtually all the part of ti C:lays 607 Jul (Anon., minerals, requires first an understanding of the Materials or another organization, with the in North geologic occurrence of deposits, then sampling, cooperation of industry, to establish useful pro- testing, and appraising of results. An under- cedures having wide application, Rather than go .nh occur at standing of the geology of the deposits is essen- into details on the many empirical and tentative :e has been tial in the early stages and is gained by first test procedures that are now in use in evaluat- iestic use as reviewing all published and other information ing bentonite and fuller's earth and that are ion, insecti. - on deposits under consideration or on similar likely to be superseded by more scientific and :vera1 years. rocks in the region. The second step is geologic technically accurate methods, only a few gen- :xpansion of field investigations, which may require mapping, eralized comments on tests will be made in the n bentonite -but reconnaissance studies have been adequate following paragraphs. jumably has for many deposits. The Wyoming bentonite Bentonite and fuller's earth are tested for use beds are generally easy to find. in the field, be- in drilling mud by adding water and mixing 'parenth.- are cause of their tendency to swell when wet and slurries of specific concentrations and measur- .ursunlu and : to develop a "popco'rn" or frothy texture caused ing viscosity, yield, yield point, and filtrate (a 1965). The by shrinkage when drying. The calcium or low- measure of wall-building properties), and mak- swelling bentonite and some fuller's earth de- ing a wet-screen analysis, according to standard posits are not as easy to find as the swelling-type procedures recommended by the American Pe- dred tons O( . bentonite, and extensive drilling is commonly troleum Institute (Anon., 1969, 1969a). The AOsrralia in required. i Oil Companies Materials Association (Anon., ere has beer, . Once located, deposits are explored by auger- 1969b) in the United Kingdom also has specifi- h for a long ing or drilling. The auger method has been cations for testing drilling muds. Tests for 970, the last widely used for bentonite, mainly because the foundry sand-bonding properties require prepa- de, was 136 : overlying rocks can be penetrated by such ration of standard mixtures of bentonite and and 100 tons ,' equipment and the bentonite sampled satisfac- sand and measurements of compression ' 16 tons from torily, particularly if the hole is cleaned when strengths of carefully prepared test pieces in iodanilling in . the top of the bentonite is reached. Power a 'manner similar to the methods outlined by iustralia. In augers are also used in some fuller's earth ex- Fisk (19461, the American Foundrymen's So- lite was im- ploration, but they have generally been found ciety (Anon., 1962a; 1963), and the Steel 1 the averagc to be unsatisfactory in searching for palygor- Founder's Society of America (Anon., 1965a). Considerablc skite (attapulgite) type deposits. These deposits Tests for taconite pelletizing bonds vary con- as developed are commonly explored with drilling equipment, siderably (Davison, 1969), but some require lletizing iron and a fishtail bit is'used to penetrate the soft certain strengths in pellets measured by- the s likely that sandy overburden, the cuttings being flushed number of times they can be dropped in speci- 'uller's earth with water. A core barrel with a toothed cut- fied intervals onto a hard surface without break- 5 Dubbo dir- ting.head is used when the top of the clay is ing (Stone, et al., 1971; Sastry and Fuerstenau, i as 1969. approkhed, and the clay is sampled with suth . 1971; Wakeman, 1972). Oil-bleaching tests of ng began in -equipment. A double-tubed barrel has bet2 fuller's earth and bentonite are commonly made vke's Bay, in found to be effective in obtaining more com- according to procedures described by the Is0 been pro- plete recovery in some deposits. Core drilling is American Oil Chemists' Society (Anon., 1958). : Canterbury. ~. also used in exploring for hectorite, because 06 Ross (1964) and Nutting (1943) also have are in lower hard rock in the overburden. given procedures for evaluating fuller's earth ormed by the j. Testing: The testing of bentonite and fuller's for use in bleaching oils. Tests for a variety of :posited in a earth is handicapped by the general absence of different insecticide, dust diluents, and carrier al., 1969). ' universally accepted procedures and specifica- uses have been described by Weidhaas and Miocene and tions. As a result, these clays are tested and Brann (1955). Most tests for absorbent gran- , this region. their valuable properties are expressed in many ules are made according to procedures in Fed- r Hills region different ways. Some of the reasons for this are eral Specifications P-A-l056A, Absorbent Ma- y, containing , the widely varying properties of the clays and terial, Oil and Water (for floors and decks), New Zealand the many different specifications outlined by available from the US General Services Ad- ry-sand bond i purchasers for many uses. The purchaser of a ministration. No standard procedures have been iterial, but it 1 single grade of bentonite may require tests of a developed for testing bentonite for use in water ncluding pel- i slurry of different concentrations, preparation impedance, but rather detailed procedures for procedures, aging, temperature specifications, testing bcntonites for canal and pond sealants have been described by the Colorado State ... 'i. and even measurements of liquid and plastic _- limits. Clearly, the absence of standardized test University Experiment Station (Dirmeyer and for bentonite ! procedures indicates the need for an effort on Skinner, 1968). .. . virtually 811 ..:. the part of the American Society for Testing & As swelling bentonites are generally more - 608 Industrial Minerals and Rocks suitable for uses requiring colloidal properties deposits is as much as IM) ft (Teague, 1912). .: district may and low-swelling ones are used in other ways, and beds of the same thickness have been a preliminary indication of the potential value stripped from low-swelling bentonite in one dis. different use of bentonite can be determined by a swelling trict in Arizona. The overburden stripped from Beneficial test. Perhaps the most common test is the sim- fuller's earth deposits ranges from a few feet to . Both bentor by simple I ple procedure of adding 2 g of dried and ground more than 75 ft. . 'i bentonite to a 100-ml graduate filled with dis- moval of w The rocks overlying most bentonite and full- -, tilled water and determining the volume of the er's earth deposits are soft and can be.loaded di. volatile mat settled bentonite in milliliters (Ross, 1964). The Wyomi rectly by self-propelled or pushed scrapers, but . delivered to Mineralogical Investigations: In addition to in places they must be loosened by bulldozers 30% moisti the testing of the type outlined in the foregoina.. and rippers before loading. Some of the over. paragraphs. information on the mineralogical burden above fuller's earth near Attapulgus, or calcium-t fuller's eartt and chemical composition of hentonote and full. GA, and Quincy, FL, contains limestone and er'r earth is also required. Mineralogical com- i matter and cemented sandstone that must be blasted. Vol- processed bt position. includlng the purity and undesirable canic rocks above hectorite deposits in Cali- or 8% wate contaminant,. is determined In some company fornia also must be blasted where stripping is laboratories. Other companies ohtain informa- done. Bentonite is mined underground by the may contaii Moisture cc tion of this type from consultants who are ex- square-set method in the New Discovery mine perienced in the use of X-ray, electron micro- near Beatty, NV (Papke, 19691, and insofar fuller's eartl scope, differential thermal analysis. petrographic as the authors are aware, this is the only benton- those of bei microscope, and other methods of investigating ite now mined underground in North America. however, hat clays. -.Heolorite in California and bentonite the ture require1 Appraisal of Field and 1,aboralory Results: Ash Meadows district, Nevada (Papke, 1969), minerals pre The final step in the evaluation of bentonite and and the Chambers [Cheto], Arizona, district, ules when co fuller's earth deposits involves the synthesis of were formerly mined underground. Early in In most pl data collected during the held investigations. this century, overburden was stripped from full- some sort of sampling and testing, and other laboratory pro- er's earth near Quincy, FL by hydraulic meth- chunks befor gram Maps are prepared locating drill huleg ods, and the clay was transported by trams. er's earth USI and showing the thicknerse5 and qualtty of clay Most bentonite and fuller's earth produced in ing to impr and thicknes,es of overhurden. Reserves of other countries are also strip mined, but under- products. Ir various grades of clay are calculated. and the ground methods are used in a few places. in- fed into a p mining cost is determined from such maps and cluding the Combe Hay district in the United the clay is th from geologic and engineering notes taken dur- in. in dia Kingdom (Anon., 1969f). Deposits in this dis- 'A ing the fieldwork. trict are selectively mined by hand, using com- by gas or oil. pressed air picks. The clay is extracted in lumps in diam and operation in Preparation for Markets 3 to 18 inches across, and it is hauled to under- ground storage facilities in mine cars drawn by v,and a I electric locomotives. It is loaded as needed fuller's earth Mining Methods: In the United StateS, vir- dryers varies tually all bentonite and fuller's earth are mined from the storage dumps onto.tNcks and hauled to the plant. The desirabli by stripping methods. Bulldozers and scrapers colloidal gra or pans are most commonly used in removing Because of variable physical properties, most bentonite and some fuller's earth deposits are greatly if .th overburden, but one company stripping near temperature Attapulgus, GA, operates a large walking drag- selectively mined. Bentonite from a single pit or bed may be separated into as many as thrqe likely to be line powered by electricity for stripping. In the to 200" typical pit, the overburden is removed in panels, stockpiles at the plant, each with different physt- loo" cal properties. Various grades of bentonite suit- in the main < the clay mined by loading trucks with dragline kept at temp or endloaders, and the overburden from an ad- able 'for different uses are then prepared from the separate piles and by blending cray from. 1964). Tern? jacent panel shifted to the mined-out area. One earth range company hauling on privately owned roads op- more than one pile. Blending bentonite as it is Part of the : erates trucks having 100-ton capacity, but most dumped on stockpiles, using earth-moving Or and the high hauling requires use of public highways and cultivating equipment to obtain a uniform clay. lighter trucks. Thicknesses of overburden re- is also common practice. The properties of The dried moved vary considerably. Most Wyoming-type fuller's earth, and particularly the palygorskite ways. In son bentonite mined is under less than 30 ft of over- (attapulgite) type, vary considerably, but de- much of the burden, but in a few places overburden is as posits tend to be more uniform than bentonite. product is gl much as 40 ft thick. The thickness of over- Commonly, an entire deposit will be suitable for or other pulv burden removed from some southern bentonite one product, and another deposit in the Same ite and mu, ground to a! .. . .~ .- " . I . . , ... .~ ..._ ... .~ ..-. . - CI 609 igue, 1972). district may have the properties required for a mesh (US Standard sieve size). Some fuller’s have been different use. earth for special markets is reported to be 95% re,in one diS. . BeneBciation and Processing Techniques: finer than IO-micrometer particle size. Granu- trlPPed from Both bentonite and fuller’s earth are processed lar grades of bentonite are also sold, and the a few feet to by simple milling techniques that involve re- wide use of absorbent granule-type fuller’s earth . moval of water and, in some instances, other requires the preparation of a coarse product. lite and full. volatile matter, and grinding to suitable sizes. The preparation of coarse absorbent granules is, be loaded di. The Wyoming or high-swelling bentonite, when in effect, a .beneficialion process, because much scrapers, but . delivered to the plant, contains approximately of the fine and medium-grained sand impurities ’Y bulldozen 30% moisture; the free water in the southern in the fuller’s earth are in the size fraction of the over. or calcium-type bentonite is about 25%. Some discarded. Attapulgus. .’ fuller’s earth contains as much as 50% volatile Hectorite and some southern bentonite, in mestone and . matter and 10% .undesirable impurities. The addition to being processed like other bentonite, :llasted. Val. processed bentonite ordinarily contains only 7 are beneficiated by a hydroclassification process. isits in Cali. or 8% water, but because it is hygroscopic, it In this process, the clay is dispersed in water 2 stripping is ’’ may contain considerably more when used. and pumped into a multistage concentrating cir- iound by the Moisture contents of most freshly processed cuit where nonclay and other undesirable ma- Fcovery mine fuller’s earth are approximately the same as terials are separated and removed. The slurry SXinsofar ’- those of bentonite. Most absorbent granules, is then passed through drum or spray-type dry- only benton- however, have been heated beyond the tempera- ers, and the concentrate is ground. A high- (rth America. ture required to drive off hydroxyl water in the- value material is prepared in one plant by cen- :onite in the . minerals present, and any moisture in the gran- trifuging a dilute slurry. apke, 1969). -- ules when consumed has been absorbed. Transportation: Several types of packaging ona, district. ;: In most plants, the raw clay is passed through are used for both bentonite and fuller’s earth. Id. Early in ~’ some sort of a clay “slicer” to break up the large For other than bulk shipments, multiwalled red from full. chunks before drying. One plant processing full. paper bags, some of which have plastic liners, iraulic mcth- er’s earth uses an extruding process .before dry- are most common. Fiber drums are used for by trams. ing to improve. properties desired in certain specialty products sold in rather small quanti- 1 produced in products. In this process the crushed clay is ties. Metal drums of 100-lb capacity are re- d, but under- fed into a pugmill, where water is added, and quired for some uses, particularly absorbent w places, in. the clay is then extruded as rods approximately granules used aboard ships and where lengthy n the United ‘/i in. in diam. Drying in most plants is done periods of storage or repeated handling are its in this dis- by gas or oil-fired rotary dryers as large as IO ft necessary. One French company uses the mod- 3, using com- indiam and 65 fl long. A fluid-bed dryer is in ern containerized method for export shipments cted in lumps operation in one bentonite plant at Col~ny, (Anon., 1969j). MQSI of the granules sold for iled to under: - WY, and a similar dryer is used in processing animal litter are packaged in 10 to 30-lb paper ars drawn by fuller’s earth at Meigs, GA. The temperature in bags, and packaging is a major item in the cost ‘d as needed dryers varies with the intended use of the clay. of the product. (s and hauled The desirable properties of both bentonite and The method of transporting bentonite and colloidal grades of fuller’s earth are reduced fuller’s earth depends on use and location of ,perties, most greatly if the clay is heated too much. The markets. Most of the processed bentonite is deposits arc temperature in dryers processing bentonite is shipped by rail in bulk hopper cars, but boxcars 1 a single pit likely lo he approximately 800°C at the inlet, and bulk trucks are also used. Bagged benton- nany as three 100” to 200°C at the outlet, and 400” to 500°C ite is commonly palletized for shipment by ifferent physi- in the main drying zone. The bentonite itself is either rail or truck. Trains carrying only ben- ,entonite suit- kept at temperatures of less than 150°C (Ross, tonite are used for large shipments to distant repared from 1964).Temperatures used in processing fuller’s points and for overseas consignments. Ore ig clay from earth range from 150” to 650°C. The lower carrier-type ships having bentonite as the only .tonite as it is part of the range is used for colloidal grades cargo are commonly used for Great Lakes and th-moving or and the higher part for absorbent granules. overseas shipments. The bentonite transported uniform clay. ; The dried clay is ground and sized in several this way is only partly dried at the point of properties of ways. In some plants, rods in rotary dryers do origin and is shipped semicrude. This method : palygorskitc much of the grinding, but most of the powdered makes it possible to load and unload it by bulk- ably, but de- product is ground with roll and hammer mills handling equipment, avoiding the costs of bag- ,an bentonite. or other pulverizers, and screened. Most benton- ging, but it requires further drying and grinding ,e suitable for ite and much of the fuller’s earth used is at or near the place used. Much of the benton- in the same ground to approximately 90% finer than 200 ite used in pelletizing taconite ore, as well as - -. - _. -.i -_ _?-.... 8 .-3 610 Industrial Minerals and Rocks $ .- most of that sold in the European markets, is cal reports related to the research on the de. 1 .The compar handled in this way. velopment of this synthetic material refer to a it has typica Fuller’s earth is transported in a similar man- randomly interstratified alumina montmorillo- ner, except that orders are not sufficiently large noid (Granquist and Pallack, 1967; Granquist, to permit trainload or some of the other bulk. et al., 1972) and SMM, which stands for sya- handling methods. Though some fuller’s earth thetic mica-montmorillonite (Wright, et d., is transported unbagged in special cars, most is 1972). The principal product made in 1972 Apparent: bagged for rail transportation. Trucking is also was advertised in a company pamphlet as True: used more extensively in the transponing of BARASYM SMM. It consists of small stacks Typical analy fuller’s earth than for bentonite, because orders of thin, parallel, irregular platelets, having an (as received tend to be smaller and are delivered directly to equivalent diameter on the order of IOOOA and the warehouses of distributors. Granules for a thickness of about 1OA. This material is this use are commonly delivered by truck to recommended for use in catalytic cracking, warehouses of the distributing chain store. hydrogenation/dehydrogenation, double-bond Trace analysi isomerization, and disproportionation, and it Synthetic and Organic-clad “Bentonite“ may be a base for reforming catalysts and a A plant (Fig. 6) operated by Barold Div., component in hydrotreating catalysts. As a NL Industries, Inc., at Houston, Texas, making petroleum-cracking catalyst, BARASYM SMM synthetic mica-montmorillonite began produc- is reported to be intermediate in activity be- Surface area: tion in 1970. An early announcement of this tween silica-alumina and zeolitic catalysts. to on calcinatioi plant indicated that one of the products was ‘hai.e.a high selectivity for gasoline, and pccdnct Saturation vo hectorite (Anon., 1970). Published mineralogi- distribution similar to silica-alumina catalysts. N, sorption Hg porosir (excludine Cation exchir Accessible * per 8 * To pyridii Synthetic t Kingdom by under the br et al., 1970) urally occun fluoride. It p the same us developed fol For severa ite has been c trade name product is pi original inorg tonite is repi cation. This clay because drated are re clay-mineral sorbing water - Organic-clad paint; to gel < having super metal, ability high tempera: Organic& United King, and in Japan FIG. &Synthetic “benronire” planr, Housron, Iexos (courresy Boroid Div., NL Industries Inc.). of the Japane CI ays 611 ch on the de. necompany's advertising pamphlet indicates name Nikkagel. It is prepared by treating :rial refer to a it has typical properties as follows: hetonite with alcohol under pressure and heat montmorillo. followed by ion exchange with an organic am- 67; Granquist. Appearance: White, free-flowing powder monium salt. A product called Organite is .tands for syn. particle size: 2040 micron microspheres prepared by further exchanging Nikkagel with ' ' For several years an organic-tieated benton- will burn off completely or even add heat in the ite has becn on the market under the registered steel furnace will continue to he sought. 1 trade name Benlone (Grim, 1962). This The manufacture of synthetic hectorite and . product is processed in such a way that the other montmorillonitelike mineral products in original inorganic exchangeable ion on the ben- the United States and United Kingdom marks ! tonite is replaced by an alkyl amine organic a technological breakthrough. Worldwide mar- cation. This reaction produces a hydrophobic kets for organic-clad bentonite and washed or clay because the inorganic ions that can he hy- otherwise purified white bentonite for speciality drated are removed, and a large part of the products are also likely to increase with general clay-mineral surface formerly capable of ad- economic growth and the development of new sorbing water is coated by hydrocarbon chains. uses and products. Organic-clad bentonites are used in making Rising costs of transportation and fuel are paint; to gel organic liquids; to produce greases two of the major pressures on the bentonite and ': having superior properties. for adherence to fuller's earth industries that are likely to have a '' metal, ability to repel water, and resistance to significant influence on future trends. The cost high temperatures; and in other products. spread between rail and ocean transportation is /. - Organic-clad bentonite is also made in the the principal reason for the loss to Greek pro- United Kingdom and France (Anon., 1970) duccrs of some of the Wyoming-type bentonite , and in Japan (Takeshi and Kato, 1969). Some market for bonding taconite ore in eastern : of the Japanese product is sold under the brand Canada. The comparatively low cost of ocean .. L .- - -_._ 612 Industrial Mine!,ais and Rocks , ... transportation is also the primary motivation be- essentially pure, and they require little concen- tually all this hind an overseas search for bentonite reserves tration during preparation for market. Most are the hydrated near deep water. Progressive increases in fuel slightly off-color and require bleaching, and will be used f costs, particularly for the low-sulfur type re- others contain as little as 10% clay that must - the mineralog) quired for ecological reasons, seem to be almost be washed and concentrated to recover market- Halloysite, I a certain forecast. Fuel shortages have caused able kaolin, din, and it is i temporary shutdowns of some plants, and prob- China clay is an ancient term originating duction statist lems related to fuel supply seemed ominous at from the use of clay, later found^ to be ka- site is acceptec the time.this article was written. olinitic, in porcelain tableware and art objects clay industries in China. This term will be used rarely in this . ologists, and s( Kaolin, Ball Clay, Halloysite, and chapter. Refractory Refractory Clay Ball Clay: Baa day is a term apparently ~ several varietic originating in the United Kingdom many dec- in the manufs Definitions and Classifications ades ago from the mining practice of prying sistance to higl Out a lump.of clay, rolling it into a crude ball, . properties of I Kaolin: The name kaolin is derived from the and loading it into a horse-drawn cart or terms of pyro Chinese term Kouling meaning high ridge, the wagon. Ball clay is defined by the American which is a met name for a hill near Jauchau Fu, China, where Society for Testing & Materials (Anon., 1971a) Pyrometric co the clay was mined centuries ago. Apparently as a secondary clay commonly characterized number of tha the first to use the name kaolinite for the min- by the presence of organic matter, high plas- touch the SUI eral of kaolin were Johnson and Blake (1867). ticity, high dry strength, long vitrification range, with that of a The term kaolin is now variously used as a and a.'light color when fired. Kaolinite is-the vestigated, whr .clay-mineral group, a rock term (consisting of principal mineral constituent of ball clay, and Standard Metb more than one mineral), an industrial mineral it typically makes up more than 70% of this Equivalent (I commodity, and interchangeably with the term type of clay. The minor differences between (ASTM Desig china clay. The following mineralogical defini- the light fired color required by this definition Society for Te tion by Ross and Kerr ( 193 1) is probably the and the white required for kaolin provide little The fusion [ most widely accepted one. practical basis for distinguishing these two fractory clays .. .. types of clay. Therefore, ball clay is .actually . the lower cutc By kaolin is understood the rock mass which a variety of kaolin, but it is treated as a separate tions (Norton. is composed essentially of a clay material that type of clay because of its wide application (Table 4). TI is low in iron and usually white or nearly in marketing and as a use term in the ceramic white in color. The kaolin-forming clays are industries. hydrous aluminum silicates of approximately The term ball clay used the United TABLE the composition 2H,O~AI20,.2SiO1,and it is is in of An believed that other bases if present represent States, United Kingdom, India, Republic Of impurities or adsorbed materials. Kaolinite is South Africa, and a few other countries. Similar the mineral that characterizes most kaolins, clay or clay used in the same products as ball but it and the other kaolin minerals may also clay is included with kaolin or china clay in No. of Cons to a in occur greater or lesser extent clays and most countries. 18 other rocks that are too heterogeneous to be 19 called kaolin. Halloysite: Halloysite occurs in two"fok one has the composition (OH),Si,Al,O,;4H&' 20 When applied as a term for an economic and the other (OH),Si,AI,O,,. The hydrated 23 26 clay commodity, the foregoing debition must form is generally a dense porcelainlike hard 27 be modified to include some indication of use clay that dehydrates at surface temperatures Or 28 and to account for the fact that most kaolin slightly above to a white or lightsolored porous. 29 now marketed is beneficiated to improve purity friable, or almost cottony-textured maten;?. 30 . and whiteness. The following definition will ap- The dehydrated form is similar to kaolinite 111 31 ply to further discussions of kaolin in this chap composition and mineral structure, and the hy 32 ter. Kaolin is a clay consisting of substantially drated form has a c-axis spacing greater than 32% pure kaolinite, or related clay minerals, that is that of kaolinite. The two forms of halloW 33 34 naturally or can be beneficiated to be white. or have caused considerable nomenclature pro! 36 nearly white, will fire white or nearly white, and lems. The system most commonly used now IS 36 is amenable to beneficiation by known methods to restrict'the name halloysirPto the hydrated 31 to make it suitable for use in whiteware, paper, form and to call the dehydrated form rnetohol- 38 rubber, paint, and similar uses. The term is loysite. However, some reports use the name applied without direct relation to purity of de- endellite for the hydrated form and the name posits. Many very large kaolin deposits are halloysire for the dehydrated form. AS Vu- .. 1.-.. Clays 613 .. tually all this clay below the surface occurs in olinitic clays are ordinarily classified, according the hydrated form, only the name halloysire to suitability for heat service, as low (PCE 19 to will be used further in this chapter, except in 26), moderate (PCE 26 to 311/2), high (PCE the mineralogy discussion. 31% to 33). and superduty (PCE 33 to 34). . Halloysite, like ball clay, is a variety of ka- A few essentially pure kaolinite clays have fu- ' ~ din, and it is included with kaolin in most pro- sion points as high as cone 35, and some refrac- Originating . duction statistics. However, the term halloy- tory kaolins and fire clays containing diaspore, to be ka. site is accepted worldwide, and it is used in the boehmite, or gibbsite have PCEs as high as art objects . clay industries, as well as by mineralogists, ge- .cone 37. rely in this ologists. and soil scientists. The principal types of clay included in the ;; Refractory Clay: Refractory .clay includes refractory clay are fire clay, kaolin. and ball aPParenl1) wveral varieties of kaolinitic clay that are used clay. Definitions of refractory kaolin and re- many dec. . in the manufacture of products requiring re- fractory ball clay are the same as given for these of prying - sistance lo high temperatures. The qualities and two types of foregoing definitions, except that crude ball, ,. properties of refractory clays are expressed in the adjective "refractory" is added to indicate 'n can or .terms of pyrometric cone equivalents (PCE) use. The definition of fire clay used in this American ;"- which is a method of designating fusion points. chapter is essentially the one by Norton (1968). 'U97la) .$ Pyrometric cone equivalent is defined as the which assigns this term to all clays that are not aracterized 7 number of that standard cone whose tip would white burning and have a PCE above 19. The high plar. ,I touch the supporting plaque simultaneously term fire thy, therefore, excludes most kaolin tion range, with that of a cone of the material being in- and ball clay because they burn white, but it :nite is the Z vestigated, when tested in accordance with the does include kaolin and ball clay that are co- I clay, and Standard Method of Test for Pyrometric Cone lored when fired. This classification of refrac- 1% of this Equivalent (PCE) of refractory materials tory clay as a group name and the threefold :S between (ASTM Designation C24) of the American subdivision are by no means universally applied. : definition Society for Testing & Materials. Other reports, including earlier ones by the au- ovide littlc 1. The fusion points of products made from re- thors themselves, have used the terms refrar- these two fractory clays range from just above PCE 19, tory and fire clay interchangeably. is actually the lower cutoff according to accepted defini- a separate - tions (Norton, 1968), to-as high as cone 37 Kaolin application (Table 4). The refractory properties of ka- 3e ceramic History and Uses: The sedimentary kaolins of the Coastal Plain of Georgia and South Caro- TABLE 4-Tsmperature End Poina lina and the residual kaolins of North Carolina he United _. of American Fyrometric Cones epublic 01 . ,, .have been known since colonial times. Smith es. Similar (1929) quotes from Sholes in his chronologi- cts ball cal history of Savannah, "1 741-Porcelain Clay as was discovered in near Savannah by Mr. na clay in "c or 1490 Duchet, and china cups made." In 1767, Josiah 1520 Wedgwood sent Thomas Griffiths to Macon wo forms: 1530 County, North Carolina, to send a shipment of ,o,,.~H,o 1580 china clay to England (Goff, 1959). Minton : hydrated 1595 (1922) recorded that, "As early as 1766 Ameri- >like hard can clays from Georgia, Florida, and the Caro- :ratures or l''' l''' linas were being sent to England in considerable ed porous, 'Wo quantities." These clays were regularly imported material. aolinite in {gi and used by Wedgwood until the clays of En- 1700 gland were available. In 1768 (Barton, 1966). od the hy- the English kaolins in Cornwall were discov- :ater than 1725 halloysite 1745 ered, which virtually ended the mining of the 1760 Georgia kaolins for more than a century. In ure prob- 1785 1876 (Smith, 1929), the mining of the sedimen- Led now is i:g tary kaolins of Georgia was started again by : hydrated Riverside Mills of Augusta in Richmond 1 merahnl- County. Mining of the Georgia kaolins has the namc ~~~~~t~~~~given BpprOXim.f.and Bppii. been continuous since that time. In addition to the namc cable only when heated et rpacifim rates (Norton. the original pottery in Savannah, a second pot- . As vir- tery was established near Bath, Aiken County, . ...~ -i -i ~ :: :: I ?_ ; .- 4.~.:.: I ...... :...... ( .. . ~-~ '. .+< ? 614 Industrial Minerals and Rocks ! SC, at an early date. This plant was destroyed inert to the other ingredients in paper, is R- .during Sherman's march to the sea (Lang et al., tained well between the paper fibers, is avail. 1940). However. kaolin mining was active able in large quantity, and the platy structure again in Aiken County shortly after the Civil of kaolinite lends itself to the production of War and has continued with only minor inter, high-gloss papers. The low viscosity of kaolin ruptions until the present. South Carolina has at both high and low shear rates is a very Y) ranked as the second leading kaolin-producing important property, because at today's very high E O state for several decades. Kaolin mining in speed production rates the coating must be ap c North Carolina started in 1888 in Jackson plied at high solids content and still give the c County (Parker, 1946), and in 1904, the earli- & correct coating thickness and opacity to the 2= est mines opened in the Spruce Pine district. paper. High-quality paper coating kaolin flows In The first kaolin operation in Vermont (Ogden, U readily when applied with very high speedcoat- c 1969) was in the early 18OOs, and most of the ing equipment, giving the paper a smooth and 0 In product was sold in Troy and Albany, NY. even film. : . a Production figures for kaolin from most areas The rubber industry uses large tonnages of 0 in the late 1800s and early 1900s are difficult to kaolin as a filler or extender in both natural and 5- trace. It is estimated that about 3 million tons synthetic rubber (Fig. 7). Kaolin is incorpo- 'Z were produced in Georgia before 1932 (Kesler, rated in the latex mix to improve properties -I 19561, after which much better statistics have as 0 such strength, abrasion resistance;-and ri- Q been available. In 1980, total production in gidity; furthermore, it lowers the cost. Through Y Georgia alone was over 6 million tons, and the years, two terms, "hard-kaolins" and "soft- South Carolina ranking second produced more kaolins" (Klinefelter et al., 1943), have bkorne than 657 thousand tons. commonplace in describing types of kaolin used Kaolin has many industrial applications by the rubber industry. The hard kaolin, though (Murray, 1963a), and new uses are still being distinctly softer than flint kaolin or flint clay. is discovered. It is a unique industrial mineral be- a very fine particle-size kaolin that tends to im- cause it is chemically inert over a relatively wide prove the tensile strength of rubber and its re- pH range, is white, has good covering or hiding sistance to tear and abrasion. The principal power when used as a pigment or extender in products in which large quantities of the hard coated films and filling applications, is soft and varieties are used are footwear and cable coven. nonabrasive, has low conductivity of heat and Soft kaolin lacks the reinforcing properties Of FIG. electricity, and costs less than most materials the hard kaolins and is used to lower elasticity with which it competes. Some uses of kaolin and improve abrasion resistance, particularly in .. ;.. require very rigid specifications including such products as floor tile and soft rubber particle-size distribution, color and brightness, goods. : . and viscosity, whereas, other uses require prac- Kaolin is used as an extender in paints tically no specifications: for example, in cement, cause it is chemically inert, has a high covering Calcined kaol where the chemical composition is .most im- power, gives desirable flow properties, is low In portant. The better grades of kaolin make up TiO?, the lead. cost, is white, and reduces the amount of latex types, ac most of the tonnage sold and, of course, have pensive pigment required. In addition, it has plifies the forn the highest value. Many grades of kaolin are very excellent suspensioii properties and, 1s specially designed for specific uses, in particu- Kaolin is u: available in a wide range of particle sizes which tics. The desir lar for paper, paint, rubber, plastics, and can be used in many types of paints. For.ex- ceramics. .s~ltingfrom t1 ample, coarse-particle kaolins are used in paints surfaces. mor< The paper industry is by far the leading con- where a dull or flat finish is required, and fi"'- stability, and sumer of kaolin (Fig. 7), and approximately particle kaolins are used in high-gloss paints. Manufacturers 50% of the tOLdl production is used in paper , Large quantities of calcined kaolin and, Water- kaolin as a rei products. Much of the paper used in today's beneficiated kaolin are used in interior Rat wall plastic more . color picture magazines contains as much as paints and in metal primers, Water-beneficiated ~ calcined kaolii by weight of kaolin. Kaolin used in paper 30% grades of kaolin disperse easily in water and insulation to j fills the interstices of the sheet and coats the are, therefore, particularly suited to latex pain's. manufacturing surface, imparting smoothness, gloss, brightness, Some kaolin is chemically treated to rnake,it ]in has helped opacity, and printability (Bundy, et al., 1965). organophilic or hydrophobic and thereby is sur'. hindered prod Kaolin is less expensive than paper pulp and able for use in exterior oil-base paints. Calcined automobile b, thereby effectively lowers paper-production kaolin, because of its resistance to abrasion and kaolin actual11 costs, and it is cheaper or more efficient than dry covering properties, is being used in increa5- form pari orb other materials used in filling and coating. It is ingly large quantities by paint manufactoren. future growth .. .. . -_ ~. - ...... 1. -.- Clays 615 in paper, is *. ,*'. 8.000 fibers, is avail. $5:. : platy structure 2 Production of 7,000 ,cositY of kaolin rates is a VCQ In Today's very hiF), c 0 6,000 ring must be ap, c nd still give th cL 0 opacity to tk I 5,000 Ling kaolin nou, In U high speed coat. E 0 2r a smooth artd In 3 4,'000 0 irge tonnages O! f both natural ani! - aolin is incorpr,. -z 3,000 -I ?we Propertic, 0 ;:stance, ald ti. a le COSt. Throush Y 2,000 dins" and "w:. 3 1. have becorn; 2s of kaolin u~rt I,000 .d kaolin. though n or flint clay. I, that tends to inr- 0 .tbber and its rc. The princip:rl 1965 1967 1969 1971 1973 1975 1977 1979 1981 ities of the bil! YEAR 3nd cable cow\ ng propertie5 nl FIG. 7-Kaolin sold or used by domestic producers for specified uses (Ampian, 3 lower elasiici:? 1980, 1983). 'e. particularly 11: md soft rubk; ~...,. ler in paintr~hc- I a high COVCIIII; Calcined kaolin is an excellent extender for used extensively in vinyl floor coverings, and mperties, is low :TI iTiO?, the leading paint pigment, particularly in surface-modified kaolin gives improved dispersi- f amount of c\. I*. latex types, and its use reduces costs and sim- bility in certain plastic systems, which will addition. it h3, * plifies the formulation of the paint. greatly increase their usage. openies 3nd i\ .' Kaolin is used extensively as a filler in plas- Historically, kaolin was first used in ceramics, rticle sizes which a tics. The desirable characteristics in plastics re- and this is perhaps still the best knobn applica- paints. For cs. sulting from the use of kaolin include smoother tion, even though the total tonnage sold for this (re used in paint. surfaces. more attractive finishes, dimensional use is small compared with that marketed for quired, and finr- ;stability, and resistance to chemical attack. paper, paint, and rubber manufacturing (Fig. tigh-gloss paint\ f Manufacturers of polyvinyl chloride (PVC) use 7). It is used in the manufacture of whitewares, 3oIin and water. kaolin as a reinforcing agent, and it makes the wall tile, insulators, refractories, and in some interior flat u.311 5 plastic mori durable. Calcined and partially face brick when a white color is desired. Spe- ater-beneficiald $ calcined kaolins are used as a filler in PVC wire cially designed grades with high green and dry ly in water 2nd insulation to improve electrical resistivity. 'In strengths are available for use by whiteware d to latex paint\ 5. manufacturing glass-reinforced polyesters, kao- manufacturers. The most important properties ated to makc it lin has helped eliminate flow problems which for this use are plasticity, strength. and fired d thereby is silil. hindered production of large products, such as color, Kaolin is used in insulators because of paints. CalcinrJ automobile body parts and boat hulls. The its properties of low conductivity, high dielec- to abrasion nnJ kaolin actually results in a stronger, more uni- tric constant, low power loss, plasticity, and ;used in increai- __ form part or body. Plastics are a major area of fired strength. Kaolin is used in casting opera- manufactiircr'. future-' growth for kaolin products. They are tions because of its excellent flowability, sus- - -. .. 616 Industrial Minerals and Rocks .. f pension properties, color, and water-release ing particle size and particle-size distribution I , characteristics. Kaolin is also used in porce- are used, hut the most accurate is based on the lain, again because of its excellent suspension Stokes principle. Size determinations can be. characteristics and good color. made by the application of this principle, be- Kaolin has many other important applica- cause settling rates in fluids are controlled by : tions, but in terms of tonnages required com- particle diameters when the attraction-of grav- . pared with the aforementioned uses, they are ity, densities of particles and fiuids, shape of rather'small. Although the following list is not particles, and the viscosity of the fluids are complete, it gives an idea of the extremely wide identical. Coarse particles, therefore, settle range of products containing kaolin as a sus- more rapidly than finer ones, and determina- pending agent, filler, extending agent, or a main tions of a given particle size and distribution c constituent because of its chemical or mineral can be made by the time-rate principle. The composition, whiteness, particle size, or other time-rate principle is equally valid for settling u properties: by gravity or when settling is auemented hv u centrifugation. A rapid tea for $ant control~I ink cement consists of the preparation of a standard, dilute adhesives fertilizers deflocculated slip of the clay in question, set- insecticides plaster medicines filler aids tling by controlled centrifugal force for pre- food additives cosmetics determined short-time intervals under such con- catalyst preparations chemicals ditions as.to effect reproducible packing of the 0IW.I bleaching crayons sediment, and measuring the apparent volume adsorbents pencils bf sddiment at each time interval. Tmical detergents particle-size analyses of filler and coating grades are shown on Fig. 8. FIG. 8-( porcelain enamels paste VISCOSITY-FIOW properties of kaolin are roofing granules very important to the paper coater because they sizing affect the functioning of the coating operation distilled water foundries as well as the final quality of the paper product: conductivity ii linoleum TWO viscosity tests are used in the kaolin indus- conductivity b floor tiles try, one to measure high shear viscosity and the For certain textiles other to measure low shear viscosity. The mea- fineness-of-gril surements are generally made on slurry suspen-~ This test is in Production Specifications: Paper Filler and dispersion (A Coater-The most important specifications for sions at 71% solids. A Brookfield fourspeed viscometer is used to measure low shear vis- - fineness gage kaolin used in paper applications are bright- brated from 0 ness, particle size and particle-size distribution, cosity. A Hercules viscometer is used to mea- sure high shear viscosity. Standard procedures by numbers. viscosity, and screen residue. Some purchasers the particles ar also require tests of abrasiveness. The Techni- and conditions are rigorously followed in mak- ing these tests. paint customel cal Association of the Pulp and Paper Industry tender must b< [TAPPII (Lyons, 1966) has given detailed in- SCREEN RESIDUE-Material held on a 325- mesh screen is regarded as grit or residue. A number.' formation regarding the properties and test pro- Ceramics-' cedures for kaolin used in paper, and only brief 100% sample is thoroughly mixed and dispersed with a dispersing chemical. After carefully de- olin sold for c descriptions of the more important tests will be rupture, castin outlined. termining the weight and percent solids of the dispersed slip, the amount of residue retained lent (PCE), f BRIGHTNESS-This test consists of drying, measurement pulverizing, forming a plaque, comparing with on the screens can be accurately weighed and percentages calculated. basic requirem a standard of known brightness, and calculating modulus of Filler ,for Paint and Plarrics-In addifion 10 ,- the brightness measured at 457 millimicrons ' strength of a with a reflectance meter constructed. calibrated. several of the properties required for use in I paper, the kaolin used in paint and plastics must The MOR me; and operated according to the requirements of Of either recta The Technical Association of the Pula and meet certain electrical resistivity specifications. The resistivity test is designed to give an indica-' supported neai Paper Industry Standard T452M-48. TGs test central part of must be very carefully done by an experienced tion of the amount of ,residual salts that might standard methc and competent technician in order to obtain be contained in the clay. The higher resistivity Casting ratc accurate and reproducible results. In general, values reflect a low soluble-salt content. A cer- hoilies cast mc a minimum brightness of 80% is required for tain Weight of kaolin is added to a specified cosity of a slip filler clay and 85% for coating clays. weight of distilled water. The suspension is if it is too visc PARTICLESm.-Many methods of determin- boiled for 5 min and reweighed. The loss of the mold or d, .. .. , -. Clays 617 j of kaolin atr fter becaucc the! is measured and controlled on shipments of oating operation kaolin used in the casting process. le paper prddili: For certain applications, particularly for re- the kaolin indu.. For certain paint applications, the Hegman fractory purposes, the pyrometric cone equiva- viscosity and ihc i fineness-of-grind test specification is important. lent (PCE) is measured. The pyrometric cone :osily. The mrj. measures the combined effects of temperature I This test is intended to measure the degree of in slurry suspc~ dispersion (Anon., 1970~)and conskts of a and time (Anon., 1952: Klinefelter and Hamlin, dustry is plagued by many different purchase and traces of zircon, tourmaline, kyanite, and , specifications and product requirements. Vir- graphite. Kaolin deposits in Latah County, tually none of these, except those outlined in Idaho, contain considerable ilmenite (Hoster. : foregoing discussions, have been. standardized, man et al., 1960). Kaolinite and halloysite and purchase specifications are frequently make up from 10 to 40% of residual deposits changed. However, the grades of kaolin now in the Spruce Pine district, North Carolina. The marketed by the major producers, those grades bulk of these deposits consists of aneular auartz.. ~~. .- described in sales and advertising brochures, muscovite, microcline, and partly aliered plagi- can, with or without blending, fulfill a wide Che (Parker, 1946). The well-known English variety of specifications. kaolins, which are IO to 40% kaolinite, consist Geology: Mineralogy-By definitions, the mainly of quartz, mica, and potash feldspar: clays discussed in this section consist chiefly of tourmaline is also present (Bristow, 1969). kaolin-group minerals. The members of this Occurrence-Most kaolin is soft and plastic FIG. 9-& group.are kaolinite, nacrite, dickite, and halloy- when natural moisture is presenttor where wa- Georgia kaoli site. With the exception of the hydrated form ter has been added to dried material:--One way thin p/ates ai of halloysite. which has somewhat more water. of describing the natural texture is by the col- of all these minerals have essentially the. same loqujal .phrase-a good whittling clay-which composition. Their overall crystal structures refers to the ease with which the clay can* are also similar, but minor differences in ar- carved with a knife. Dry kaolin is ordinarily rangements of ions in octahedral positions, friable, and a common but not a diagnostic test stacking of unit layers, crystal habit, etc., are for it is its stickiness when touched to the sufficient to cause the use of separate names. tongue. Some types of kaolin, which have ap Kaolinite is, of course, the most common mem- parently been under considerable overburden or ber of the group, and halloysite obviously forms which contain introduced silica, are hard and halloysite deposits. The other two members of are sometimes referred to as flint -kaolin. the group rarely occur in economic deposits. Though much more lithified than plastic varie- Structurally, kaolinite consists of an alumina ties, this so-called flint kaolin is softer than most octahedral sheet and a silica tetrahedral sheet. flint clay referred to in the sec:ion cn fire Clay. These sheets form triclinic crystals. The theo- which also consists of kaolinite. retical structure formula of kaolinite is (OH),- Kaolin and related clays occur in several djf- - .. Si,AI,O,,, and the theoretical composition is ferent types of deposits. Many kaolin deposlu -.., SO, 46.54%, AI,O, 39.5%, and H,O 13.96%. throughout the world are in the form of tabular '. There is relatively little ionic substitution in the lenses and discontinuous beds in sedimentar). mineral lattice, although there is evidence sug- rock. Most deposits of this type are of ere- gesting minor substitution of iron for aluminum taceous age or younger. The shapes and lateral generally "iiregul in some kaolinite. The perfection or degree of extent of such deposits vary appreciably. D,c' ward into the p ordering of kaolinite crystals varies consider- posits as much as 60 ft thick are common In tered weathered ably. By interpretation of X-ray diffraction some districts. and bodies of kaolin are known commonly 'cont: .. ,' data, Murray and Lyons (1956) have shown to extend laterally for more than a mile. Ex. regular masses c that the crystallinity of Georgia kaolin ranges tensive sedimentary deposits of this type Occur rock that were o from poorly ordered to very well ordered forms. in the Georgia-South Carolina kaolin belt blocks or otheru Other investigators (Brindley and Robinson, (Anon., 1970i), Arkansas bauxite region (60:- water. Residual 1946; Range, et al., 1969) have found similar don, et al:, 1958), and Ione district, California Spruce Pine dis! variations in ordering in kaolinite from several (Johnson and Ricker, 1948) [Fig. IO]. " 1946); the Arka localities. The more perfectly ordered forms of Residual kaolin deposits occur in weathered et al., 1958); 1 kaolinite commonly occur in hexagonal or sub- rock, and they are at or very near the surface. and Keller. 196 nia (Cleveland, hexagonal crystals. Growths of crystals along except where they formed during ancient wea- United States '(I the c-axis into accordionlike or vermicular thering cycles and were later buried hy Younger many other cour forms are also common. Fig. 9 is an electron rocks. Most residual kaolin deposits have micrograph which shows both the hexagonal mon in Czecho: formed from igneous rock. The age of kaolin Brazil (de Souz: thin plates and vermicular stacks of kaolinite. formation is commonly controlled by the age Of 1972). The clays described in this section contain. in the present land surface rather than the age Of Some kaolin their natural occurrence:a wide variety of min- the parent rock. Residual kaolin deposits arc Occur in rocks I ...... - .- .. _. . . Clays 619 'ne:ally is XJ IS mainl! smectitc, ne. GOethitr, kyanite, an,, .tab Count!. lite (HO~I~,. nd halloysit: dual deposil, 3arolina. Th: 'gular quartz. hered plapi,,. .'own Engli\h linite, con\i\t :ash feldspar: )W, 1969). >ft and pla\t,,. FIG. 9-Electron micrograph of %where u;,. Georgia kaolin showing hexagonal :tal. One w3, thin plates and vermicular forms is by the cni. of kaolinite. . : clay-whirl, e clay can hc 1 is ordinarii) diagnostic IC\: ,uched to itlr ,hich have ap. overburden are hard 2nd flint kaohn I plastic var!~. mfter than nit>,: n on fire cl:~;.. in several di!. :aolin depouh arm of tahit!:;; n sediment:!:) e are of C:: - generally irregularly shaped and grade down- altered. Such deposits are ordinarily in irregu- pes and latc::tl ward into the parent rock through partly al- larly elongate pods or pipelike bodies aligned ireciahi!'. IX : -,j_ tered weathered saprolite zones. They also along joints. faults, or other permeable zones ;e comni(rn 18) commonly contain iounded boulders and ir- that allowed movement of warm or hot aqueous ,din are knoun = regular masses of fresh or only partly altered solutions. Some deposits of this type also occur n a mile. I.*- rock that were originally in the centers of joint in altered tuffs and are bedded. As with the re- his type ozili: E blocks or otherwise'protected from percolating sidual type, the age of hydrothermal kaolin for- a kaolin IKL 5. water. Residual kaolin deposits occur in the mation is not necessarily related to the age of e region (Cic>i- P Spruce Pine district. North Carolina (Parker, .ict. California the host rock. Most hydrothermal clay deposits sY 1946); the Arkansas bauxite district (Gordon, are probably no older than Tertiary, though g. 101. get_. al., 1958): Latah County, Idaho (Ponder some occur in rocks that are much older. Inso- I in weathere? and Keller, 1960); Alberhill district, Califor- far as the authors are aware, deposits in the ar the surfax E nia (Cleveland, 1957); and elsewhere in the Little Antelope Valley, California (Cleveland, g ancient wcil. 9-United States (Fig. IO). They also occur in 1957), contain the only hydrothermal kaolin ied by yOUn?C' !.:many other countries and are particularly com- now mined in the United States. It is used for deposits h~c E mon in Czechoslovakia (Kuzvart, 1969) and refractory clay. However, kaolin formed by this age of kaoli? 'i Brazil (de Souza Santos and de Souza Santos, process occurs at many places in the western d by the age 1972). states, and deposits were formerly mined on a han the as0: small scale in several mining districts. deposils arc Origin-The two fundamental geologic proc- . -_ 620 Industrial Minerals and Rocks .. kansas is of Wilc kaolinitic clay 01 throughout a muc; can be related to - kansas. Similarly, cannot all be relat type of kaolin del understood occurs Valley and Ridge of the United Stat parently formed by nous minerals by sinkholes. Probabl terials were mainly of carbonate rock. based on the pre: bauxite in the cent, enclosing envelope the kaolin from the of the sinkholes. Strange as it ma origins are least unr extensive belt in G d Ma@ repion which have been stu A PrOducinp district + Producing d11tric1 I, mineralogists and % A Minor or inaclive dirtlid +- Minor 01 inactin diivCl source of commerci BALL CLAY REFRACTORY CLAY a 500 M~IS have investigated th, the kaolin or the mi Producing district Producing district .. - 0 Mi- w inactin dirtrkt 0 Mina a inxtw district _- has been transportt center about expla large deposits of fir FIG. 10-Map showing kaolin, ball clay, halloysite, and refractory c/oy disfricts in the US. have formed in en sediments being dc containing much ms esses that form most of the clay minerals of Knowledge regarding the origin ofkaolin de- Furthermore an ad? the kaolin group are weathering (Keller, 1964) posits in the United States varies considerably. Of the deposits mus and hydrothermal alteration (Sales and Meyer, The origins of some of the deposits are reason- facts: (1) some d 1949). These processes under certain condi- ably well established, but geologists have widely grained than others tions remove elements other than silicon, alumi- differing opinions on how other deposits dant accordionlike j num, oxygen, and hydrogen, the constituents of formed. Clearly, many of the scattered ka- (3) gihbsite is prese these clays. The clays form as the other ele- olins in western states formed by hydrothemla1 in others; (4) ligni. ments are removed from preexisting minerals processes, hut few such deposits have been Slg- organic matter are and possibly by the growth of new atomic ar- nificant sources of kaolin. In the Arkansa and (5) smectite is rangements from materials in solution. Though bauxite region (Gordon, et al., 1958) and in variable quantities. most kaolin minerals form in these ways, the Latah County, Idaho (Hosterman, et al.9 One of the first gl origin of valuable deposits is quite another mat- 1960), are districts containing both tram- gia kaolin was by 1 ter. Certainly several commercial clay deposits ported clay and residual kaolin formed, by the deposits but dit throughout the world have formed by hydro- weathering of igneous rock. In both distn?? Veatch (1909) con thermal processes, and others have formed in the kaolin grades downward through saprol!llc place by the weathering of other rocks. How- member of the Crc zones into parent rock, which is nepheline loosa, is the most im ever, many of the large high-grade deposits of syenite in Arkansas and granodiorite in Idaho. tion in Georgia. kaolin occur in sedimentary rocks and have Also, in both districts, kaolin transported from I+ either been (1) transported and deposited as the residual material occurs in sedimenta? the formation in G~ by its stratigraphic kaolin; (2) altered from previously transported rocks-in marine shale in Arkansas and In mcks by processes related to surficial weatber- lacustrine beds in Idaho. However, this ex- that the material n ing, submarine or subaqueous alteration, or planation of origin is inadequate to account for Formation was de'ri, posthurial (diagenetic) changes; or (3) com- all the kaolinitic clays in the regions con(a1nlnK decomposed rocks binations of these possibilities. these districts. The transported kaolin in AI- The greater pan of ! - p"" . I Clays kansas is of Wilcox age (early Eocene), and land surface for a very long period of geologic kaolinitic clay occurs in rocks of this age time. Just before the beginning of the Cre- throughout a much more extensive region than taceous, the Piedmont region was uplifted and can be related to the nepheline syenite in Ar- tilted southeast, Streams rapidly carried the kansas. Similarly, the Miocene clays in Idaho weathered residue to the Cretaceous sea. Veatch cannot all be related to granodiorite. Another postulated that an enormous quantity of sedi- type of kaolin deposit that is reasonably well ment was dumped rapidly at the stream mouths. understood occurs as sinkhole fillings in the forming extensive sand flats. Fine clay parti- valley an$ Ridge province in the eastern part cles were deposited in nonpersistent and lenticu- of the United States. This type of kaolin ap- lar beds of white clay in the deeper and quieter parently formed by the leaching of other alumi- waters near the stream mouths. He considered nous minerals by downward-moving water in the Tuscaloosa in Georgia a nonmarine deposit. sinkholes., Probably the parent aluminous ma- Smith (1929) concluded that the basal Cre- terials were mainly residuum from the solution taceous sediments in Georgia were Upper Cre- of carbonate rock. This explanation is in part taceous and correlated them with the Midden- based on the presence of cores of gihbsitic dorf Formation of eastern South Carolina. bauxite in the centers of such deposits and the Smith believed that Veatchs explanation of enclosing envelopes of cherty clay separating origin was essentially correct, except that he the kaolin from the carbonate rock in the walls agreed with Neumann (1927) that the kaolin of the sinkholes. was deposited in saltwater. Cooke (1943) Strange as it may seem, the deposits whose assigned the basal Cretaceous sediments to the origins are least understood include those in the Upper Cretaceous under the name Tuscaloosa. extensive belt in Georgia and South Carolina which is still used. Kesler (1963) believes that which have been studied by many geologists and in east-central Georgia there is no basis for sub- mineralogists and which lead the world as a dividing the Upper Cretaceous, and he found source of commercial kaolin. Virtually all who that the kaolin lenses have no preferred strati- have investigated these deposits agree that either graphic position within the formation. Kesler the kaolin or the material from which it formed theorized that feldspathic sands were deposited has been transported. Areas of disagreement as delta sediments above sea level and were center about explanations of how such very subsequently altered to kaolin. The kaolin was large deposits of fine-grained white clay could separated from the coarser sediment and de- i in the US. have formed in environments in which some posited at pints of lowest elevation. As the sediments being deposited consisted of sand kaolin accumulated in the ponds, sand was containing much more iron than does the clay. Furthermore an adequate explanation of origin washed from the margin into and over the edge of kaolin de- of each deposit, forming gradational and inter.. considerably. of the deposits must account for the followhg fingering contacts. LS are reason- -facts: (I) some deposits of kaolin are finer :shave widely grained than others; (2) some contain abun- Bates (1964) reviewed the origin of the .her deposit: dant accordionlike booklets and some do not; Georgia kaolins and summarized the minera- scattered ka- (3) gibbsite is present in some deposits and not logic and geologic data, some of which support hydrothermal in others; (4) lignitic layers or layers rich in a marine origin and some a freshwater origin. lave been sig- organic matter are present in some deposits: Hinckley (1961) suggested that face-to-face the Arkansas and (5) smectite is present in some deposits in flocculation of kaolin particles in a marine en- 1958) and in variable quantities. vironment would result in the properties that man, et al.. One of the first geologic studies of the Geor- distinguish a so-called "hard" kaolin, whereas both trans- gia kaolin was by Ladd (1898); he described edge-to-face flocculation in freshwater would 1 formed by the deposits but did not discuss their origin. produce a less dense, "soft" clay. Buie (1964) both districts. Veatch (1909) concluded that the lowermost proposed the possibility that volcanic ash was ugh saprolitic member of the Cretaceous system, the Tusca- first altered, to montmorillonite and then to ka- is nepheline loosa, is the most important clay-bearing forma- olinite. This is a radical departure from pre- ,rite in Idaho. tion in Georgia. He indicated that the age of viously proposed theories of origin, and much ,sported from the formation in Georgia was determined only more detailed field and laboratory work must sedimentan by its stratigraphic position. Veatch believed be done before this hypothesis can be ade- dnsas and in that the material making up the Tuscaloosa quately tested. Jonas (1964) concluded from ever, this ex- Formation was derived from disintegrated~and a detailed petrologic study that .the originally to account for decomposed rocks of the Piedmont Plateau. deposited sediment was muscovite, feldspar, and Ins containing .Tb? greater part of the Piedmont region was a quartz, and that postdepositional alteration and kaolin. in AT- 622 I. recrystallization produced the kaolin deposits taceous in age contain more vermicular crystal IDAH-Filler. now mined. growths and coarser particles than do the de. ficiated in Latah Recent studies of spores, pollen, and inverte- posits known to be of Eocene age. .. A its occur as re2 brate fossils in and associated with kaolin indi- Major Kaolin-Producing Countries: United granodiorite and cate that many of the deposits thought to be States-GEORGIA-SOlJTH CAROLINA KAOLIN terman, et al., 19 Cretaceous are of Eocene age (Buie and Foun- BELT-The principal reserves and the major Mineralogical an tain, 1967; Cousminer and Terris, 1972; Scru- kaolin-producing centers in the United States deposits contain I dato, 1969). a possibility suggested by Eargle are in a belt extending from Twig@ County in ite and that the c (1955). The first announcement of the Eocene the central part of Georgia to Lexington County ing almost all 1 age for any of the deposits was by Buie and in west-central South Carolina. 'This same bell kaolin, quartz, i Fountain, who on the basis of paleontological extends southwest from Macon to Anderson. quantities of othc evidence established the presence of middle Eo- ville, GA (Zapp, 1965), and west to Eufaula. NORTHCAROLI ' ' cene strata beneath some. of the commercial AL (Warren and Clark. 1965). The Anderson- :. . mary kaolin (the kaolin deposits and above others. In one of the ville and Eufaula districts contain appreciable here as cornmonl: studies, Cousminer and Terris (1972) con- kaolin resources, but both are centers of pra ' try for hydrother, cluded through palynological work that some, duction of refractory kaolin. and refractory sidual deposits c if not all, of the sedimentary kaolin is middle bauxitic materials, and no kaolin, as defined in weathering) alteri Eocene in age. Results of palynological studies this report, is now produced in either district. ~~~ ~~ (Parker, 1946) is by R. H. Tschudy of the US Geological Sur- The deposits in the Georgia-South Carolina kaolin is a mixtui vey on samples collected by Patterson have con- belt occur in sedimentary rocks a short distance and is used prima firmed that some of the kaolin deposits are of seaward.from the crystalline rocks of the Pied. These deposits ger Late Cretaceous age or older, and that some are mont'region. The major mining and beneficia- 40% kaolin and no older than Claiborne (middle Eocene), tion activities are in Twiggs, Wilkinson, and quartz, hornblende Tschudy's work also revealed that sand beds Washington Counties, Georgia, and in the vi- removed by wet b of Paleocene age are present in the kaolin belt. cinity of Aiken, SC. Large reserves of fine- duce a usable prod This raises the possibility that some of the ka- particle-size kaolin have been discovered in the TEXAS-Near K olin deposits may be of Paleocene age and that 10 last to 15 years in the vicinitv of Wrens, GA. of earlv Eocene~ ~. P kaolin deposition took place during several which is in the eastsentral part of the. belt. mined kdbenefic different intervals of geologic time. '-Other reserves are scattered throughout the bdt. clav (Fisher et~ al.~~.. The recent findings on the range in age of Very large potential resources of off-color hi@ scribed these depo Georgia kaolin deposits reinforce our opinion iron clay and deposits under overburden that IS They contain 40 to that the deposits have had a very complex his- too thick to be stripped profitably, at present. is a byproduct of a tory and origin, and the theories advanced to are scattered throughout the seaward parts Of OTHERSTATES- - .- , date do not provide adequate explanations. the belt. the. past or has bec Probably the purity of the kaolin is the result ALABAMA-Kaolin is mined from the Tusca- mercial quantities i of some sedimentary winnowing process, an loosa Group in Marion County, Alabama Illinois (Grim, I? idea favored by Kesler (1963) and others, as (Clarke, 1964). It has been mined in this area 1970), Mississipp evidence now available suggests that the ulti- for 40 years, and approximately 1 million tons Mexico (Glassmire mate source was aluminum silicate minerals in has been shipped. This kaolin is relatively Pure 1969), and Virgi the crystalline rocks to the northwest. The en- and is easily beneficiated by removing qUan.2 1920). vironment in which the deposition took place is and mica. Most of the production from this R ESOURCES-R~S yet to be established, but it was probably simi- district has gone into various ceramic producls. United States of a lar to the present coast of Georgia and South CALIFORNIA-Filler-type kaolin is mined and than the lower gra Carolina. where there are abundant offshore processed near lone and Bishop, CA. The lone least 1 billion tons. sand bars and swampy, muddy lagoons and clay is sedimentary Clays 623 nicular cvsta1 IDAHo--Fil!er-type kaolin is mined and bene. porter of kaolin in the world (Anon.. 19728). . an do the dr. ficiated in Latah County, Idaho. These depos- China clay is the United Kingdom's chief ex- _. its occur as residual weathered products of port, and almost the entire output comes from ntries: unilrd granodiorite and as lacustrine sediments (Hos- the SI. Austell area of Cornwall. Historically. JNA KAOLIX terman, et al., 1960 Ponder and Keller, 1960). the china clays in Cornwall were discovered by !nd the majoi Mineralogical analyses show that some of the William Cookworthy (Barton, 1966) in the United Stath deposits contain halloysite in addition to kaolin- mid-1700s to be suitable for making porcelain. kgs County in ite and that the deposits are variable, some be- In Cornwall, an extensive region of kaolinized +ton Count! ing almast all kaolin and others containing granite has been formed by hydrothermal al- This same bell kaolin, quartz, orthoclase, mica, and minor teration of feldspar (Bristow, 1969). The gran- $0 Anderson. quantities of other minerals. ite masses were emplaced in Permian time and :St to Eufau!l, NORTHCAROLINA-Near Spruce Pine, a pri- are now exposed over large areas of Devon and The Anderson. mary kaolin (the term primary kaolin is used Cornwall. The china clay deposits typically :In appreciabk here as commonly applied in the kaolin indus- occur in funnel or troughlike bodies narrowing :enters of pro. try for hydrothermal-type deposits and for re- downward. Hot acidic solutions are thought to ind refrlctor, sidual deposits of kaolin formed by in-situ have migrated upward, guided by structural 1, aS defined in weathering) altered from pegmatite and aplite weaknesses such as faults and joints, and then either district. (Parker, 1946) is mined and beneficiated. This to have been trapped under a roof of relatively iouth Caro:!ni kaolin is a mixture of kaolinite and halloysite impermeable rock. The hot solutions attacked short dirlancc and is used primarily by the ceramic industry. the granite, altering the feldspar and mica to ks of the Pied. These deposits generally contain approximately kaolinite. Quartz, tourmaline, and mica are the and beneficia. 40% kaolin and halloysite, so that the mica, principal impurities. Drilling has shown ka- Vilkinson, atad quartz, hornblende, and other minerals must be olinization to exist at depths of more than and in the W. removed by wet beneficiation methods to pro- 800 ft (Bristow, 1969). serves of fin<. duce a usable product. In most places, the clay can be mined using ;covered in thc TEXAS-Near Kosse, Texas, a kaolin deposit high-pressure water jets, but sometimes blasting of Wrens, G.A. of early Eocene age in the Wilcox Group is or ripping is required to loosen the rocks. Se- rt of the hr\i mined and beneficiated as a filler and ceramic lective mining is very important because of ighout the hcl! clay (Fisher et al., 1965). Pence (1954) de- variability in the various deposits. Much blend- off-color high scribed these deposits as nonmarine in origin. ing is done to produce a uniform product. As rburden that I, They contain 40 to 70% quartz, and the kaolin the rock face is washed, the slurry containing ily, at prexn:. is a byproduct of a glass-sand operation. the kaolin in suspension flows to the lowest %wardpan3 o! OTHER STATEsKaolin has been mined in point in the pit. The slurry is then pumped into the pas! or has been reported present in com- spiral classifiers which remove the coarse ma- 'om the TILSC:~. mercial quantities in Arkansas (Tracey, 1944) ,. terial. After this initial classification, the slurry nty, Alah:arwb Illinois (Grim, 1934), Minnesota (Parham. is pumped to the surface of the pit where hy- led in this arc3 1970). Mississippi (Conant, 1965), New drocyclones remove finer sand and mica par- 1 million ICII!~ Mexico (Glassmire, 1957), Vermont (Ogden, ticles. The slurry is then thickened in large- relatively pikx 1969). and Virginia (Ries and Sommers, diameter tanks. A series of refining tanks is moving qwf:! 1920). used to remove the heavier coarser particles. tion from t!i~< REsouRcEsResources of kaolin in the After primary classification, the slurry is fed to ilmic product, United States of a quality equal to or better centrifuges to separate the coating kaolin from n is mined 21:: than the lower grade clay now mined are at the filler grade. The kaolin is dewatered by CA. The 101~ least I billion tons. The one grade of kaolin filter presses and is dried. Two new processes :Bates, 19J!i. about which there is concern for long-range have been designed-the tube filter press ; hydrotherm.1! supply is the very high grade fine-particle-size (Clark, 1968). which utilizes extremely high white clay suitable as a paper coater and for pressures and produces a relatively dry filter n is found In certain other speciality uses (Buie, 1972). Re- cake that needs little if any additional drying, Zitronelle FCI. serves of this type of clay probably total 100 to and a process catalogued as micromineral sepa. .mation ranp 200 million tons. Potential resources of kaolin, ration (British Patent No. 1,222,508), which Id the recoYcI. including discolored and very sandy clay and produces a rather clean pure kaolin. The only OP that below more overburden than can be profit- More than 2.7 million tons of kaolin were y, Most of Ihc ably stripped at present, are several times the produced in England in 1970, of which 2.1 mil- industry. Kc. estimated reserves. lion tons were exported (Anon., 1972f). The were nmcJ L: United Kingdom-The United Kingdom is exports are handled through the ports of Par I dated midJic second only to the United States as a producer and Fowey. The kaolin is transported to port ?f kaolin or china clay and is the largest ex- by rail or truck. Most,ships that transport a,. ka- .,. . . 624 Industrial Minerals and Rocks ~- .. ' .. . : olin are in the 400 to 500-ton range, but 1000. ita, pegmatites, and other crystalline rock; oc- granitic and met; ton vessels can be accommodated at Par and CUI at many localities in Brazil, and rec&tly Wieden, 1969). 10,000-ton vessels at Fowey. very large transported deposits have been dir- the ceramic indur USSR-Kaolin is mined and processed in covered. The deposits in weathered rocks have and rubber indust several districts in the USSR (Petrov, 1969). been mined for domestic use for many yean. 000 tons were mi Residual, hydrothermal, and sedimentary de- The large transported deposits were not de. 100.000 tons of I posits are worked. One kaolin deposit in the veloped at the time this report.was prepared, beneficiation tech1 Transcarpathian region consists of virtually but exploration by American interests and Bra. BULGARIA-Sed pure dickite (Rusko, 19731, and other deposits Zikn government agencies suggests that prD probable Pliocenr in this same district consist of mixtures of ka- duction is likely. One region containing sig- Bulgaria (Karana olinite, dickite. and halloysite. The Gluhovetski nificant deposits of transported kaolin is along vidual deposits ar district, southwest of Kiev, approximately mid- the Jari River (Colligan, 1973). a tributary of associated with sa way between the cities of Zhitomir and Vinitsa, the Amazon. The deposits along this river arc karst area undei is one of the major centers of production. The of Pliocene age (Klammer, 1971). They are ar limestones. The n' best grades of kaolin are produced from de- much as 35 m thick and extend for several ki- sands is about 18 posits formed in weathered granite. Production lometers. Reserves are considerably more than an iron content 01 from this district is about 700,000 tpy, and 50 million tons. Another region in which the used locally in the both wet and dry beneficiation methods are kaolin deposits are being evaluated is along the CZECHOSLOVAKI used. Another major producing district is in the Capim River approximately 200 km- south of principal produce vicinity of Prosyanovski in the Dnepropetrov- BClem (White, 1973). rope. The major c ski region. The deposits in this, area also occur GUXANA-very large transported kaolin de- ., Karlovy-Vary, Plz in weathered granite and gneiss. Nearly 1 mil- posits are associated with bauxite in Guyana ' in west Bohemia ( lion tons of kaolin were produced from this re- and Surinam (Moses and Mitchell, 1963). is primary, is of I gion in 1966. Reserves of kaolin in the Pro- These deposits are in sedimentary rocks under- the production of syanovski district are estimated at 160 million lying the Coastal Plain seaward from a shield and refractories. ? tons. Other large kaolin deposits occur in area of ancient crystalline rocks, The'regional has been mined, a Kazakhstan, where a large kaolin beneficiation geology is, therefore, similar to that of the duction will proba plant was reported to be in the advanced stages Georgia-South Carolina kaolin belt. Japanex tons. Reserves arc of planning in 1968. The largest sedimentary interests are reported to be mining 300 tons of 1 billion tons (Ku kaolin is the Pologa deposit on the Konok River kaolin a month and shipping it to Japan state controlled, a near the Pologa Station. Many other kaolin (Ampian, 1973). .>: low price. The I deposits have been described by Petrov (1969). OTHER COUNTIiIEs-Both residual and trans- other Eastern Eur The Russian kaolin is used in the paper, ce- ported kaolin deposits occur at several places last two years a s ramic, rubber, and chemical industries. in Chile, Colombia, and Venezuela (Malkovskf shipped into Weste Minor Kaolin-Producing Counbies: North and Vachtl, 1969~). Hydrothermal deposiu Germany (Anon., America-MExlco-Most of the kaolin in are also present in Chile, as indicated by the DENMARK-A S: Mexico is in primary deposits originating by association of kaolin with alunite. Small ton- oh is mined on I hydrothermal alteration of Tertiary rhyolitic nages of kaolin are also produced in Peru.. marily for the Dal rocks (Pasquera. et al., 1969). The deposits Paraguay, and Ecuador (Ampian, 1973). penhagen (Almebc are found in almost every state, but the largest Europe-The kaolin operations in contine* the output goes in commercial deposits are in the central part of tal Europe are mostly small scale because Of alumina refractor! the country. All the kaolin in Mexico is dry the scarcity of high-grade deposits. Most Of the Products. The qua processed for use in the paper, ceramic, refrac- kaolin produced is still used by the ceramia enough to be US~C tories, rubber, chemical, and pharmaceutical industry and as filler for paper, and only minor for paper. industries. Reserves are estimated to be more quantities are sold for other applications. EASTGERMANV- than 500 million tons. At present, more than Germany produces nearly 500,000 tpy kaoh ary kaolin deposit 100,000 tpy is mined and processed. Kaolin is the main production being from Bavaria. many (Storr, et al.. imported from the United States for paper- kaolin deposits in Brittany in France are being from an area norti coating applications. worked to a much greater extent, and Produc- Colditz. The iron South America-ARGENTINA-The kaolin tion from this area will increase substantially. mercial deposits rai production in Argentina in 1969 was 80,905 Czechoslovakia. where the production is COLT as high as 2%. M. tons (Anon., 1971b). Most of this kaolin was trolled by the state, is becoming an impoflmt ceramic purposes, I mined in the Blaya Dougnac, Don Carlos, and producer, and exports kaolin to other EuroFm rubber filler are in Maruja districts, Chubut. Districts in Rio Ne- countries. mated to be consic gro and San Juan also had active mines in AUSTRIA-Economically important kaolin lion tons. recent years. deposits of'primary origin occur on the BG- -FRANCE-Many BRAZIL-Kaolin deposits in weathered gran- hemian Massif,a deeply eroded complex Of kaolin from distric . . granitic and metamorphic rocks (Holzer and the Massif Central in central France. The de- ]line rocks DE. Wieden, 1969). Most of this kaolin is used in posits in Brittany are of approximatelythe same and recentiy the ceramic industry and as filler in the paper age as those in Devon and Cornwall in England lave been di,. and rubber industry. In 1966, more than 450,- (Anon.. 1972f). In Brittany, the deposits are -ed rocks have 000 tons were mined in Austria, but less than all primary in origin: and the deposits around many yeao. 100,000 tons of this was processed using wet the Massif Central are both primary and sec- were not dc. beneficiation techniques. ondary (Damiani and Trautmann, 1969). was preparcd. BULGARIA-Sedimentary kaolin deposits of About 80% of the French production is from :rests and Bra. probable,,Pliocene age occur in northwestern Brittany and is near the coast. Production is :ests that pro. Bulgaria (Karanov, et al., 1969). The' indi- more than 250,000 tpy. Most kaolin is used :ontaining "ip. vidual deposits are small because the kaolin is by the ceramic industry, but its use as a filler kaolin is along associated with sand which fills sinkholes in a for paper, paint, and rubber is increasing be- a tributary <,! . karst area underlain by Lower Cretaceous cause of improved processing techniques now this river arc s limestones. The average kaolin content in these being implemented. France imports about ). They arc a, sands is about 18 to 25%. The best kaolin has 250,000 tpy, mainly from England and the for several k8. 'an iron content of 0.6 to 0.8%. The kaolin is United States to meet its requirements for ably more than used locally in the ceramic and paper industries. kaolin. n in which ~hc .: CzEcHosLovAKIA-Czechoslovakia is the GREECE-Low-grade deposits of kaolin suit- 1d-k along thc 0 km south 0: 'rted kaolin dc. tile in .Guyana :itchell. 1963 I. ry rocks undcr. 1 from a shield 3. The repiom! to that oi th: belt. Japanrrc ing 300 tons c1 g it to Japan .idua! and tran\- t several placc, ela (MalkovsLi iermal depouir ndicated by thc lite. Small ton- duced in Peru. an, 1973). ins in continen. cde because d ,its. Most of thc ,y the ceramics and only minor plications. Wet ,000 tpy kaoiin. m Bavaria. Thc irance are kin$ st, and produc. se substantiall!. ,duction is con. SPm-+-Spain has the fourth largest produc- 2g an impofinn' filler are increasing. Reserves are esti- tion of kaolin in Western Europe; in 1970, the . ' other European to be considerably more than 100 mil- total was 285.000 tons (Anon., 1972f). By 1976, according to the National Mining Plan, ,portant Lacjl1!1 ANcE-Many small companies produce the production will be more than 500.000 tons. cur on the led comple\ from districts in Brittany and around Both primary and secondary deposits are mined ~ -. .- 626 Industrial Minerals and Rocks in Spain (Martin Vivaldi, 1969). The deposits beneficiation techniques become available and which produce c are widely scattered, but the commercially im- water supply to the area is improved. A severe industry in lndor portant production is concentrated in the north- water-supply problem for wet beneficiation of IRAN-The hrj west near Galicia-Asturias and in the east near kaolin exists throughout South Africa. .. in the central pan Cuenca-Teruel-Valencia. The primary deposits SWAZILAND-Kaolin deposits of economic (Khadem, 1969). of Galicia were formed by the hydrothermal importance are found in the Malilangatsha deep weathering i alteration of mylonitized granite; reserves ex- Mountains of the Manzini district (Hunter and limestone sequenl: ceed 300 million tons. The secondary deposits Urie, 1969). Kaolinized dikes ranging.in width fine ceramic and in eastern Spain are Cretaceous in age and are from 3 to IO m, 75 m in depth, and as much serves are about 1 : principally kaolinitic sands ranging from 10 to as 620 m in length have been studied. The JAPAN-Large I 20 m in thickness. Reserves are estimated to be kaolin ranges from white to pale red, depending deposits occur in more than I billion tons. Most of the produc- on the iron content. The entire production of Shimazaki, 1969) tion is used by the ceramic industry, primarily some few thousand tons is exported to South throughout the is1 in refractories, but as beneficiation techniques Africa. .,.. were formed by h! improve, more will be consumed in the paper, OTHER COuNTRIES~therAfrican countries canic and granitic paint, rubber, and other industries that need having minor kaolin production include An- weathering of grai tiller clays. gola, Arab Republic of Egypt, Ethiopia, Kenya. rock. The second: WEST GERMANY-The largest kaolin mining Nigeria, Tanzania, Malagasy, Mozambique, and lower Pliocene ag, district is in the townships of Hirschau and Morocco (Ampian, 1973; Malkovskq and 20 m in thickness Schnaittenbach in Bavaria (Anon., 1972f). The Vachtl. 1969~).The deposits in the Pugu Hills duced in Japan (4 deposits are sedimentary in origin, derived from distr!ct %near Dar es Salaam, Tanzania. arc. in many deposits decomposed granite in the Niab hasin moun- among those having economic potential. The ',< tons. The major tains, and are Triassic in age. These deposits kaolin is in upper Tertiary sandstone which is fine whiteware, p consist of a mixture of quartz, feldspar, and 30% white clay (Harris, 1969). Attractive paper fillers. Min kaolin and are ahout 40 m thick. The material features of these deposits include a location difficult each year is wet processed to recover about IO to 20% only 50 km from deep water and a possible values and the diR kaolin, and the quartz and feldspar are also glass sand coproduct. However, an attempt in property to sustai salable products. Because of the high content the early 1950s to develop and export this operation of a wet of quartz and feldspar, sophisticated hydro- kaolin failed. KOREA-Primar: cyclone-processing stages are used to make very Asia-SRI LANKA-The best known kaolin cur in Korea (Hei precise particle separations (Anon., 1972f). deposit on Sri Lanka is the Boralesgamuwa dry and wet benefi Other areas in West Germany where kaolin is field, south of Colombo. The kaolin is probably process the kaolin worked are Oberneisen near Frankfurt, Hesse, Pliocene or Pleistocene in age, is sedimentav. paper, and rubber and Westphalia (Lippert et al., 1969). and occurs in layers and pockets 4 to 19 ft thick 000 tons are mine OTHER CouNTRlEs-Srnall tonnages of ka- (Pattiaratchi, 1969). The percentage of kaolin markets; over half olin are produced in Romania, Sweden, Portu- ranges from 20 to 85, and the major imPUriV Japan for use as g gal, Yugoslavia, and Belgium (Ampian, 1973; is quartz. The kaolin is used for ceramic% posits. consisting o Malkovskg and Vachtl, 1969h). paper, rubber, paint, and as an insecticide car- halloysite: are in th Africa-REPusnc OF SOUTHApnrcA-The rier. The production is small, about 3000 tPY. southernmost Kore: kaolin deposits of South Africa have been de- and the estimated reserves are about 8 million MALAY Sih-Resit rived from the weathering of granite, shale, and tons. granite is being m tillite (Coetzee, 1969). Kaolin is mined near INDIA-Kaolin and related clay materials are make paper-filler 'c Capetown. Grahamstown, and Durban. With mined in many locations in India (Arop.Ya,* Kuala Lumpur. T the exception of the large deposit of altered till- wamy, 1968). The major producing area 1s !" present production ite near Grahamstown (Murray and Smith, the vicinity of Chaibasa. The deposit mined I* PEOPLESREPUB, 1973), deposits are small but of good color this district occurs in weathered granite. High- only was used first i and quality. The Grahamstown deposit is very quality kaolin is also produced in the ViclnltY in recent trade jou large, with reserves in excess of 50 million tons. of Kundra, Chattanur, and Quilon, Kerala. The being mined on a but the quality ranges from excellent to very kaolin in this region occurs in altered felds- for export. Histori, poor and it changes in very short intervals both pathic granite, and the altered zones are as Tae-Chen district ii horizontally and vertically. Approximately much as 10 m thick. were the principal 50,000 tons are used locally in South Africa, INooNEsiA-Large residual kaolin depositr making fine cerami the ceramic industry taking more than 50% of altered from granite are known to occur on the deposits are assoc! the production. Other uses include insecticides, islands of Belitling and Banka (private corn. Silurian phyllite. T rubber, paint, plastics. and pharmaceuticals. munication). Although the deposits are large. lo white, and it is The large deposit at Grahamstown could be little is known about the quality of the kaolin, somably. this distri, potentially valuable in the future as advanced There are small wet-processing operationr this was not veri& _.. ,,, >..,:.- ...... - ...... ~. , .- e available and which produce china clay for the ceramic regions in China include Singtze. Loping, Yu- roved. A SC~~~~industry in Indonesia. kan, and other districts in Kaingsi Province, beneficiation ol IRAN-The largest kaolin deposit in Iran is and Tzuhsien, Kaiping, Fengyn, and Chingh- Africa. in the central part of the country near Simiron sing, Hopeh Province. Kaolin in deeply weath- (Uadem, 1969). This deposit is the result of ered granite occurs at several localities in deep weathering at a diastem in a Cretaceous Kwangtung Province which surrounds Hong limestone .sequence. The material is used for Kong. This kaolin formed from granite may fine ceramic and refractory purposes. The re- he the clay advertised for export because it is serve~are about 15 million tons. much closer to the ocean than most other . JAPAN-Large primary and secondary kaolin deposits. deposits occur in Japan (Fuji, Okamo, and In addition lo the kaolin mentioned in the Shimazaki, 1969). The deposits are scattered foregoing paragraph, kaolinitic clays asso- throughout the islands. The primary deposits ciated with diasporic and bauxitic clays in were formed by hydrothermal alteration of vol- Carboniferous, Permian, and Mesozoic coal Lfrican countrlG canic and granitic complexes and from in-situ measures occur' in Szechuan, Honan, Kupeh, on include hn. weathering of granite, pegmatite, and volcanic and Fukian Provinces and elsewhere. Several %thiopia. rock. The secondary deposits are lacustrine, of of these clays are called kaolins and are used lozambiquc. lower Pliocene age, and range from 20 cm to in ceramic products. Residual kaolin formed .rnOVSk? a,)i! '20 m in thickness. About 200,000 tpy is pro- by the weathering of arkosic sandstone occurs n the Pug,! iw; duced in Japan (Anon., 1972f). The reserves in Szechuan Province, and deposits formed Tanzania. A,r 'in many deposits range from 5 to 20 million from weathered feldspar in granite and peg- potential. 'I k :tons. The major uses of the kaolin are in matite occur at several places in China. Idstone which ,, :fine whiteware, pottery, refractories, and as PHILIPPINES-Philippine kaolin deposits are 69). AIlraclt~~ 'paper fillers. Mining in Japan becomes more primary and are generally small and scattered. :Jude a IOC~I,~~ diflicult each year because of increasing land Most are hydrothermal in origin, although one and a piwhir .values and the difficulty in purchasing enough deposit called Bukidnon is believed to have :I, an attempt property IO sustain reserves required for the formed from in-situ weathering of a dacite and export ~h:: operation of a wet-beneficiation plant. (Cornsti, 1969). The major deposits are on KOREA-Primary and secondary kaolins oc- Luzon and Mindanao. The bulk of the kaolin it known kar.i~ cur in Korea (Heikes and Kim, 1965). Both is used in refractories, tiles, and sanitary wares. Boralessarnim I dry and wet beneficiation methods are used to Very little is used in the paper and rubber in- aolin is prohahi) process the kaolin for the ceramic, refractory, dustry. The reserves are limited and transporta- , is sedirnentAr? :paper, and rubber industries. More than loo_- tion is costly; these factors and the variable :s 4 to 19 It Ihi. Exploration, Evaluation r ._ 6) Leachability . ' ~ .. .sz.*=. Leachability is fractions to deter, Exploration in the United States: The princi- Grit percentage is determined as explained i!J that can be attail pal productive deposits of kaolin were found in the section on end uses and specifications and and oxidizing leac the Carolinas and Georgia in the late 19th and is an important crude evaluation test. A,gd minations are ver) early 20th centuries. Most discoveries were in rule of thumb is that as much as 5% grit Can lishes the level of outcrops in stream beds and road cuh. Today, be handled easily using air-flotation techniqua kaolin can be utilii exploration is carried out in geologically favor- Much higher percentages of grit can be to meet brightness able areas, taking into account topography and dled using wet beneficiation methods, but * For air-float cla elevation. Geologic and topographic maps, if higher the grit percentage the, lower the * are determined. F, available, and aerial photographs are used to covery of kaolin and the higher the cost. Nor- ness, green and dr) lay out exploration drill-hole patterns. Most mally in the United,States, a maximum of lo determined. Chen exploration holes are drilled to depths of as to 15% grit is set for the upper limit of @ alumina are commc much as 200 ft and on 400- to 800-ft centers. percentage, but if the kaolin is of unusuallY a refractory pro. Many deposits were missed in the past because. high quality, a higher grit percentage Can be important are t only random spot drilling instead of pattern tolerated. Centage of particle In size, percentage drilling was used. Also. because drilling was Particle-size distribution is important bsay smenite, limited to 50 or 60 ft. many goad deposits at from this test the percent recovery coating titularly Of area, and the quant. greater depths were not discovered. Auger or and filler clays is determined. For many Yern sary to attain the lo fishtail drills are used to the top of the kaolin an important delineatidn point has been After all the tesi bed, and then a special core barrel is used to percent of particles than 2 micrometen in less ated and the over! core the kaolin. Cores are difficult to mover, (Lyons, 1966). This percentage Can vaq size thicknesses of the and special care by expert drillers is necessary from as low as 50% to as high as 90% In * mined, a decision i to get good core recovery. In many areas, two Georgia deposits. This is an important test k- .. Clays cause brightness, viscosity. and other physical is of a quality suitable for any of the present by sand are pent. properties are closely related to fineness. Also, uses for kaolin or a potential aluminum re- :3 as 200 ft a predetermined fineness range must be sup- source, or whether the property should be plied io the beneficiation plant to meet the filler dropped. The economic limits of the ratio of .I and coaling requirements and lo provide for overburden to kaolin that can be mined eco- uniform process procedures. It is, therefore. nomically range between 6 and 8 to I, depend- necessary to blend kaolins from various de- ing on the type of overburden, and the reclama- tion requirements imposed by federal and/or state law. After coring t;f, If the decision is made io keep the deposit kness of the Y~,,. for future mining, then additional drilling is .d the thicknell o! done on 200- or 100-ft centers. From this drill- map is prepared ing information, additional maps and cross sec- :e located and t& action containing 92% of the tions are prepared, from which a stripping and Ind the kaolin arc n 2 micrometers in siFe is. mining plan is devised. :nt to the crud< The classification of a deposit as potential the kaolin is prc. Both low shear and high shear viscosity tests aluminum clay is of relatively recent practice as degritted crude clay and on the a result of the interest in using kaolin as a raw divided into %. material lo produce aluminum. The United States is dependent on foreign sources baux- testing. The IC*. of ite to supply approximately 90% of its alumi- 0 short section, t, num requirements. The purchase of bauxite ' section that mi) represents a significant outlay of dollars which high viscosity, contributes to our balance of payment deficits. ne way. The ?.!: Kaolin clays in Georgia and South Carolina erized. The ptii. contain 35 to 39% AI?O, and represent a very rluated using thc sizable resource from which aluminum could be kaolin: No. 2 coating clay (80% finer than 2 microme- recovered if the economics become favorable. :sidue ten) a minimum brightness of 85.5% is re- A report by the National Materials Advisory Board (Anon., 1970i) reviewed the various I . quired, and for No. 1 coating clay (92% finer processes for extracting alumina from non- bauxite ores. An article (Anon., 1973b) also described a process to make aluminum using high-alumina clay which is chlorinated and reacted with manganese to form aluminum. Coal is used as the fuel. ed as explaincd tn specification\ an2 :ion test. A god Preparation for Markets h as 5% grit can Mining and Beneficiation: The mining of tation techniqucr kaolin is a highly sophisticated mechanized grit can be han. operation (Murray, 1963b). After extensive methods. but Ihc testing to insure that the deposit can be bene- he lower thc rc. ficiated to meet the necessary quality standards er the cost. Nor- of the various process industries, mining plans maximum of IO are prepared which include clearing of timber, >per limit of gri: removing the overburden by either motorized 1 is of unusuall? scrapers or large draglines, establishing a land- ercentage can Ir reclamation schedule and program that must be approved by officials in some states, such as mportant becaux Georgia, and establishing approved environ- :overy of coatin6 mental controls on water drainage and dust For many ycan emanation. After the overburden is removed nt has been the and the top of the kaolin deposit is exposed, additional drilling is done in order to provide 2 micrometers In rburden thicknesses and the detailed information of quality variations within centage can mr?' e deposit have been deter. the deposit so that a predetermined mining :h 90% in thc as program can be followed that will meet the mportant. test h. .. .. - .. Industrial Minerals and Rocks ~ .. requirements needed by the beneficiation plant. ing agent such as a hydrosulfite is then added. Detailed maps showing the elevations of the and the iron reacts and forms a soluble sulfate, top of the kaolin, thickness of the deposit, all which is removed during the dewatering step. quality determinations, and lateral extent are The dewatering of the flocculated kaolin slip is prepared which are used to control the mining accomplished by using high-speed centrifuges, '. operation properly. rotary vacuum filters, or filter presses. Some- The principal beneficiation steps are shown times the flocculated slip is thickened by using PROSPECTING &NO in Fig. 11. After the kaolin is exposed and thickeners or centrifuges before filtration. After MINE PLANNING tested. the kaolin is mined by shovels, draglines, filtration, the kaolin filter cake can be extruded motorized scrapers, or front-end loaders. The to noodle form and dried in apron dryen or kaolin is either loaded in trucks or dropped rotary dryers or it can be redispersed to the into a blunger which disperses it in water with fluid state and spray dried, drum dried, or the aid of a dispersant chemical to form a clay- shipped in slurry form as 70% solids in tank water slip or slurry. This slurry is pumped from cars. ~-. . .. the blunger to a degritting station, where, by The foregoing paragraph is a simplified de. the use of settling boxes, screens, and/or hydro- scription of the wet process. Other processes cyclones, the coarse foreign particles called grit are used to produce brighter and whiter kaolins are removed. Grit is defined as that material and to reduce viscosity. Flotation (Greene and coarser than about 44 micrometers. After de- Duke, 1962), selective flocculation (Bundy and gritting, the kaolin slurry is collected in large Berberich. 1969). and magnetic separation storage tanks and then pumped through pipe- (lannicelli, et al., 1969) are used to remove lines to the beneficiation plant iron'inki 'titanium impurities to produce kaolin' .. Two basically different processes are used to in the range of 90% hrightness.._This kaolin produce a salable kaolin product-a dry proc- has a blue-white shade. ess and a wet process. The dry process is sim- The most recent. development for improving LEACHING ple and yields a lower cost and lower quality brightness and whiteness is a high-intensity (To whiten and product than the wet process. In the dry proc- magnetic separator which removes substantial brighten kaolin) ess, the properties of the finished kaolin reflect quantities of iron and titanium mineral im. generally the properties originally found in the purities. The intensity of these newly developed crude kaolin. Therefore. deposits containing units ranges from 18 to 22 kilogauss. The main the desired qualities of brightness, low grit con- feature of the separator system (Fig. 12) is a tent, and particle-size distribution must be Io- canister filled with a special type of fine steel cated by drilling and testing. In the dry process. wool which provides a uniform magnetic field the kaolin is crushed to approximately egg size, through which the kaolin slurry is pumped 2nd dried in rotary dryers, pulverized, and air- the magnetic particles retained in the'matris. floated. The air-floating process removes most Periodically, the magnet is deenergized, and a of the grit. high volume of water, under pressure is back . The wet process (Fig. 11) has been highly Rushed through the matrix to flush out the Im- developed in recent years to produce kaolin purities (Oder and Price, 1973). . products of uniform and predetermined physi- Delaminated kaolin is produced by splittin% cal and chemical properties. Crude kaolin of apart the larger books or stacks of kaoh variable quality can he wet processed to pro- (Fig. 13); this yields a product in which the duce a uniform high-quality product. individual plates tend to be wider. thinner. and The kaolin slurry is pumped from the mines whiter. The processes used for'delaminatlo* to the plant, where it is stored in large tanks. include wet attrition grinding (Gunn and Mor- Kaolins of various qualities are blended at the ris. 1965) and extrusion (Lyons, 1959). De- laminated kaolin has special application in 1iP.h.'- DISPERSING c mine tanks or in the terminal tanks at the plant CHEMICAL to provide a feed for the beneficiation plant that weight paper coatings, in paint films, and In ~2 will produce products to meet specifications. special rubber applications. The first step in the wet process is to fractionate Calcination is another widely used process Io the kaolin slurry into coarse and fine fractions produce special products from kaolin. WheT by using continuous centrifuges, hydrocyclones. kaolin is heated to approximately 1050°C. it Is or hydroseparators (Fig. I11, After fractiona- converted to mullite, silica-alumina spinel. and tion. the kaolin is leached to remove ferrugi- cristobalite. The product is whiter, brighter. nous coloring compounds. In this step the ka- better hiding properties when used in thin film FIG. 11--1/1 olin is acidified with sulfuric acid to a pH of applications, and is more abrasive. about 3.0 to dissolve the iron, A strong reduc- Other special processes are used to modify then added, .hie sulfate, itering step. -aolin slip ii centrifuge,, ms. somc. ed by using ation. Aftrr be extruded 'n dryers or xed to n dried. )lids in tank 'mplified de. :er procesrer hiter kaolin, (Greene and (Xndy and : separation 1 to remnvc Jduce kaolin This kaolin )r improvini ligh-intensi!) s substant;;,l mineral im. ,ly develowi! _.is. The main 'tg. I?) is 2 of fine SIPC! iagnetic ficid pumped and the matrt\ .gized. and a sure is bark 1 out the in,. I by spliltin~ .s of ka01i:i :n which thc thinner. anJ de1aminalio.n nn and %lor. 1959). Dc. ition in light. ilms, and /n ed proceSS to lolin. \Vhm IOSO'C. it i\ a spinel. and brighter. h:w I in thin film d to modif? Industrial Minerals and Rocks widely depending on whether it is in pulveriied, for the producti, lump, bead, or in some other form. Lump clay If this projectio SliEL nml will generally weigh 60 to 65 Ih per cu ft. future of the kai YAIR X Spray-dried clay in bead form will weigh 40 to and dynamic. 50 Ib per cu ft. Depending on the fineness of Competitive p pulverization and moisture content, pulverized calcium carbonai kaolin will range from ahout 35 Ib per cu ft for silicates, alumina air-floated kaolin to as low as 20 Ib per cu ft Ground calcium CAN SIER WALL for some very fine particle Size finely pulverized fer color, and ha: kaolin. however, has be Kaolin is shipped in hulk form in boxcars, gives befter hidir TOP VIEW in covered hopper cars, and in slurry form in ground calcium c tank cars or in tank trucks. Kaolin is also tages with respec shipped in 50-lh multiwall bags in boxcars or in acid finishes, ( SLURRY OUT nate panicles ar, YffiNiT STEEL, in trucks when the customer cannot handle the 7-material in bulk. Export shipments are made in gloss, (3) it giver bulk ore-type carriers in 2,000- to 15,000-ton high solids, and MATRIX- lots, in either lump or spraydried form. Some cipitated calcium export tonnage is also shipped in special paper paper to give hig YAGNLT COIL- ,bags of 25- to 50-kilo capacity. receptivity. CANISTER- Markets and Consumption: The variou! Talc competes markets to which kaolin is supplied were dis- .~ caulking compouh cussed in the section on end uses. In 1980, In paints, talc gi\ SLURRY IN I] 7,878,993 tons of kaolin were produced and ting in interior pai * sold in the United States (Table I). Fig. 7 Precipitated si1 SIDE VIEW shows the tons of kaolin sold for use as paper reinforcement to I SECTION THRU MAGNET filling and coating, rubber, ceramics, refracto- strength, modulus ries, and other uses for the years 1929-1979. abrasion. These FIG. 12-Diagrammatic illustrotion of mag- Since 1930, the market for kaolin has increased paper to improve netic separator used in removing iron and very tenfold. In the 1930s, practically all the kaolin TiO, used in pap fine-grained titanium minerals from kaolin. sold to the paper industry was used as filler, one-third to one-h: whereas today the proportion of filler clay to the precipitated si1 the surface of the kaolin chemically to improve coating clay sold to the paper industry is ap only in conjunct its function in many systems, such as ink, rub- proximately 1 to 2. Coating clay has a much specific requireme ber, paint, and plastics. These surface-modified higher value per ton than filler clay, and this ~ Alumina hydra1 kaolins can he hydrophilic, hydrophobic, or increase in the use of coating clay has had more turing to give higl organophilic. effect on the kaolin industry than any other EOl. It is seldor, Transportation: The kaolin products are single factor over the past 40 years. In 1980. with kaolin. Alun shipped from the heneficiation plants in bulk, the total value.of kaolin sold was reported at times more expens in slurry form at 70% solids, and in multiwall $527,098,609 (Ampian and Polk, 1981). The drive to prc paper bags. Kaolin is supplied commercially in Exports of kaolin to Europe, Japan, and paper has led to th pulverized form, in lump, generally in the shape South America have increased significantly ments which are I of small extruded noodles, in spray-dried bead from 1965 to the present largely because Of and spherical (A form, in small pellets, or in flake form. The the increasing use of coating clay by the paper Shand, 1973). Tt weight per cubic foot of the kaolin will vary industry. In 1980, 1.,392,000 tons of kaolin rior properties suc ,having a value of $133.7 million, was ex- proved printahilit!, ported (Ampian and Polk, 1981). The largesf much more expen: export tonnages of kaolin are shipped from ments will be blen Savannah, GA, and Port Royal, SC. bin improved pro! tions but will not. Future Considerations and Trends: Cooper pigment. (1970) has estimated that the demand for ka- olin from the United States in the year 2000 Ball Clay Kaolin sbck Pbter will be five to six times greater than the amount now being sold. He has estimated a high of History and Use. FIG. 13-Diagrammatic illustration of the 23,680,000 tons and a low of 16,710,000 ton: Of the material no. splitting of kaolinite booklets or stacks into He has assumed a technological and ecOnOmlC in the United Star thin plates by the delmination process. breakthrough that will allow kaolin to be used Paris, TN in 186( ...... -. ?I. ., ..... -7.; . , .- .- r .. __ - - Clays 633 the production alumina and aluminum. t is in pulverized. for of (Hosterman, 1973). The first clay shipped to arm. Lump clay If this projection is even partly correct, the out-of-state consumers was that produced in 55 Ib per cu ft. future of the kaolin industry is indeed exciting west Tennessee in 1894 by a Mr. I. Mandle. will weigh 40 to and dynamic. Later, the industry expanded into Kentucky, n the fineness of Competitive products for kaolin are ground and the ball clay districts in the western parts ntent, pulverized calcium carbonate, talc. precipitated silica and of these two states competed with districts in 5 Ib per cu rt for silicates, alumina hydrate, and plastic pigments. the United, Kingdom (Anon., 19694) for the Ground calcium carbonate is cheaper, has bet- world leadership in production. In 1981, more i 20 Ib per cu ..1, finely pulverized ter color. and has lower oil absorption. Kaolin, than 916 thousand tons of ball clay was pro- howeve;, has better Row characteristics and duced in the United States (Ampian, 1982). gives better hiding or opacity. In paper uses, More than 80% form in boxcan, of this tonnage was produced pund calcium carbonate has several disadvan- by companies active in Tennessee and Ken- n slurry form in tages with respect to kaolin: (I) it is reactive Kaolin is aIm tucky. The other states producing ball clay are in acid finishes, (2) the ground calcium carbo- Mississippi, Texas, and California (Fig. 10). 8s in boxcars nate particles are too large to produce high annot handle the Ball clay is also produced intermittently in gloss, (3) it gives poorer Row characteristics at Maryland. mtSare made in high solids, and (4) it is more abrasive. Pre- to 15,000-la" Ball clay is used principally in the manufac- 0- cipitated calcium carbonate is used in coating ture of vitreous china sanitary ware, electrical :ied form. somr paper to give higher brightness and better ink in special papcr porcelain, floor and wall tile, dinnerware, and -. receptivity. arlware (Phelps, 1972). It is also used in re- r Talc cornwtes with kaolin mostlv in paint. fractory products, ceramic glazes, and porcelain I: The variou, 'caulking compounds, and drywall c&np&nds: enamel slips. pplied were di,. 'In paints, talc gives better brightness and flat- Geology: Miflerdogy-Kaolinite is the prin- uses. In 1YNrr. :ling in interior paints. e produccd md' cipal mineral in the ball clay deposits in Ten- ;. Precipitated silica and silicates give better nessee and Kentucky, but other clay minerals ible 1). Fig. 7 .reinforcement to rubber, produce higher tensile are present and nonclay minerals vary appre- for use as papcr strength, modulus of elasticity, and resistance to ciably in abundance. The kaolinite in these de- .amics, refratlo. abrasion. These materials are also added in 3ars 1929-1970. posits is fine-grained, and much af it is poorly paper lo improve brightness and to extend the ordered. The main clay minerals other than lin has incrmsd Ti02 used in paper. However, kaolin is only 'ly all the kaoliri kaolin are illite, smectite, chlorite, and mixed- one-third IO one-half as expensive; consequently layer clay. Quartz is by far the most abundant s used as fillcr. the precipitated silicas and silicates will be used of filler clay to nonclay mineral; in some deposits it makes up only in .conjunction with kaolin to achieve as little as 5% of the clay, but in others, as industry is ap .specific requirements. lay has a much much as 30% (Olive and Finch, 1969):The Alumina hydrate is used in paper manufac- other nonclay minerals ordinarily present occur r clay, and !hi\ turing-to give higher brightness and to extend iy has had mwc in very minor or trace amounts and include -TiO,. It is seldom used alone but is blended plagioclase, potassium feldspar, and calcite. Or- than any othcr .with kaolin. Alumina hydrate is two or three fears. In 19SO. ganic matter in the form of black leaf imprints times more expensive than kaolin. .. and disseminated lignitic and peaty materials #as reported at .: The drive to produce very lightweight coated k, 1981). are common in most ball clays. paper has led to the development of plastic pig. Occurrence and Origin-Ball clay is ex- E, Japan, and rments which are uniform in size. lightweight, :d significantly tremely plastic. Deposits range from very light :and spherical (Anon., undated; Heiser and gray to nearly black. Most deposits are lenticu- ely because of $and, 1973). The pigments give some supe- iy by the paper .. lar bodies varying considerably in size and por properties such as gloss, opacity, and im- shape. Some are more than 30 ft thick and tons of lnolin :proved printability to coated paper hut are illion, was extend over areas 1000 ft wide and 2500 ft :much more expensive than kaolin. These pig- long, but most deposits are smaller. The physi- ). The largo: 'ments will he blended with kaolin to give cer- shipped fron: cal.properties of a typical deposit vary con- tain improved properties for particular applica- siderably, and layers and pockets mined from sc. tions but will not replace kaolin as a coating rends: Coopt:' $merit.i. a given deposit are commonly separated in dif- ferent stockpiles suitable for a particular use. lemand for k3. Most deposits in Tennessee and Kentucky the year 2000 :Ball Clay Ian the amounl p are in beds of Claiborne age (middle Eocene), but a few, including one mined, are in Wilcox lted a high @f History and Uses: Probably the first deposits ;,710,000 tons. ;of the material now known as ball clay mined beds (lower Eocene) (Olive and Finch, 1969). and emnomic $ the United States were those worked near The deposits mined in Texas near Henry's ilin to he urd Paris, TN in 1860 for use in a local pottery Chapel, northeastern Cherokee County (Fisher Industrial Minerals and Rocks ...... et al., 1965) are also in Wilcox beds. The ball ball clay in Kentucky and Tennessee, appar- late 1800s. This clay mined in Paoola County, Mississippi ently are caused by carbonaceous impurities, -: sold as a filler < (Bicker, 1970). is in a formation of Claiborne and the clay burns white. The deposits arc 1909). Deposits age, and the deposits are approximately the believed to have been transported from altered ; and used for ma) same age as younger ones in Tennessee and granite and other igneous rocks. Watts, Blake, i hurst and Teague Kentucky. The deposits mined in Stanislaus Bearne, and Co. is the major producer of ~' of halloysite. was ...... ~3 County, California, are in beds of Paleocene or ...Y British ball clay...... :i .- diana and used fa Eocene age (Cleveland, 1957). Those mined Ball clay occurs at several localities in india after World Wa. on a small scale in the Hart district in eastern (Arogyaswamy, 1968). but production is lim- ' ' major source of San Bernardino County, California, are in hy- ited, and in recent years India has been an im- been the approxi drothermally altered Tertiary rhyolites (Kelley, porter of ball clay. The best quality ball clay ~ from the Dragor ,1966). produced is in the Than district of Gujarat. . (Fig. IO), by Tt Most ball clay occurs in transported sedi- Other deposits are mined in two districts in... essed into petrol mentary deposits, but one minor producing dis- Kerala. -.. . .:.:;:;:~:- Filtrol Corp. pln trict in California contains hydrothermally Evaluation of Deuosits: The ..DrosDectinr -_ f Mining to suppl altered clay. The deposits in the Tennessee, Ken- techniques for ball clay are very similar to Minor tonnages tucky, and Mississippi districts are in sedimen- those outlined for kaolin. The most commonly . ' from this same mi .tary formations cropping out along the eastern used tests are very similar to those used for ' Halloysite occurr edge of the Mississippi embayment. According evaluating the ceramic properties of-kaolin and Utah has also bee to one theory of origin (Olive and Finch, 1969), heat-resistant properties of refractory clays. brick, firebrick, ti they accumulated in an elongate broad valley. Chemical analysis for soluble sulfate in ball . Sant, 1964). Ha The abundance of plant remains and organic clays.,is commonly required because this ma. . used in portland c matter associated with this clay indicates that terial 'can be tolerated in only very minor 1971). Deposits the depositional basins probably were swampy. amounts in most ceramic products. . kaolinite and hall, Distribution of Deposits: (Inired Stares-Any Preparation for Markets: Ball clay is mined (Hosterman et al.. attempt to estimate the resources of ball clay is by stripping methods and trucked to plants. lar clay-mineral CI based on piecemeal information. The reserves, Most plant processing involves primarily drying (Parker, 1946) ai primarily in Tennessee and Kentucky, total and grinding to a suitable size. A few planu and other product probably as much as 100 million tons, and are air-float part of their output. Most ball c!ay is Geology: Mine owned by eight or ten different companies; they packaged in paper bags, but some is shipped in lar to kaolinite tt are thought adequate to sustain the industry for bulk carload lots in both crude and processed guished without 100 years (Phelps, 1972). Additional reserves form. In recent years, some ball clay has been : (Brindley, et al.. are in the producing districts in Mississippi, shipped in tank cars. This clay is prepared for . structures comml shipment by deflocculation ,in water, and it b Texas, and California. Potential .resources of micrographs of.de shipped as 60 to 62% solids (Pbelps, 1972). ; loysite) are ordin low-grade ball clay, which probably would re- Such slurries are used by plants manufacturing ' quire beneficiation for market, occur in the vi- eral. The shortco ceramics by the slip-casting method. .- a not all metahallc cinities of all of these districts. The prospects . Future Considerations and Trends: The PI* are also favorable for the discovery of more form. 'A. reliable duction of ball clay in the United States has (001) spacing of deposits of kaolinitic clay having the physical grown rather consistently for the last several . . properties'of ball clay in several southern states. 10A: as halloysite decades, and continuation of this trend is fore- halloysite, the spa Furthermore, if the term ball clay is applied cast. Nationwide demands are likely to be 2 which is essential to such deposits as the hydrothermally formed to 2.3 million tons in the year 2000 (Cooper. kaolinite. Halloys clay at Hart, CA, many areas in the western 1970). In general, the ball clay industry faces fied by the greate states are likely to contain large deposits. little competition from foreign sources, and grams of samples Orher Counrries-The principal ball clay de- exports are appreciably greater than imports. Nonclay miner2 However, the major districts in Tennessee and posits in the United Kingdom occur in the loysite vary consi. Bovey Basin southeast of Dartmoor in Devon- Kentucky are in the central part of the coun- try and as rail transportation costs increase. a Some deposits, si shire, the vicinity of Petrockstow in north mine, Utah, are e; Devonshire, and in the Wareham and Poole greater proportion of the demands in the POPu- Iotis coastal region may be satisfied by imports. only minor quan regions of Dorsetshire. These ball clays occur sisting chiefly of in sedimentary rocks of Tertiary age. consisting bearing. minerals mainly of lenticular units of sand, clay, and '- /.-.t and manganese OX Halloysite ~ .! . lignite of probable lacustrine origin (Scott, deposits, silica is 1929). The clay is very fine grained plastic History and Uses: Apparently the first curs in the form kaolin ranging in color from off-white to dark Ioysite used in the United States was that mined and poorly crysta. brown and gray. The darker colors, as in the on a small scale near Rising Fawn, GA in the deposits are interr- .. . . . -:. ____-I . L . . _., ... . .- late 1800s. This clay is reported to have been era1 in western United States are closely asso- sold as a filler or extender in food (Veatch, ciated with alunite. Gibbsite and manganese 1909). Deposits near Gore, GA were mined minerals also occur in some halloysite deposits. and used for making alum about 1912 (Broad- Occurrence and Origin-Small deposits of hunt and Teague, 1954). A few hundred tons halloysite occur at many places in the United of halloysite, was mined from deposits in In- States, but known deposits large enough to mine diana and used for pottery and alum during and profitably are rare. The deposits in the Dragon 'calities in indla after World War 1 (Callaghan, 1948). The mine, Utah, the major producer, are two large oduction is ii(,,. major source of halloysite in this country has pipelike bodies replacing lower Palrxoic lime- has been an in,. been the approximately 1 million tons mined stone near the contact with monzonite porphyry Wality ball cia) from the Dragon mine, Tintic district, Utah (Kildale and Thomas, 1957). The two bodies yict of (Fig. lo), by The Anaconda Co. It is proc- are separated by a zone of iron-oxide deposits two districts in essed into petroleum-cracking catalyst at the extending along the Dragon fissure (Morris, Filtrol Corp. plant in Salt Lake City, Utah.' 1968). The occurrence of these deposits and he prospcctinF Mining to supply this plant began in 1949. the minerals associated with them clearly indi- very similar tu Minor tonnages of halloysite were produced catc that they formed by hydrothermal activity. most common!) from this same mine before 1949 for other uses. Other deposits thought by Papke (1971) to those used fi,, Halloysite occurring at several other places in have formed hydrothermally occur in the Ter- es of kaolin anti Utah has also heen used in making light-colored raced Hills, Washoe County, Nevada. These :mtory Cl+, brick, firebrick, tile, and as a paper filler (Van deposits are bedded and apparently altered sulfate in ha(: Sant, 1964). Halloysite in Nevada has been mainly from tuff. The halloysite in the Gore :cause this n,;. used in portland cement in recent years (Papke, district, Georgia, is bedded and occurs in the I~Yvery minm 1971). Deposits in Idaho consisting of mixed Armuchee Chert of Devonian age (Broadhurst lucts. kaolinite and halloysite are used in refractories and Teague, 1954). An adequate explanation II clay is mined (Hosterman et,al., 1960), and deposits of simi- of these deposits has never been advanced, but cked to plant, lar clay-mineral composition in North Carolina the extent of the beds suggests that they are of Jriniarily drying (Parker, 1946) are mined for use in ceramics sedimentary origin. Halloysite mixed with ka- . A few pl;,n~, and other products. olinite in the Spruce Pine district, North Caro- 40st ball cia? i\ Geology: Mineralogy-Halloysite is so simi- lina (Hunter and Hash, 1953; Parker, 1946), ne is shippd in lar to kaolinite that the two cannot he distin- and the Bovill district, Idaho (Hosterman ; and procchd guished without careful mineralogical work et al., 19601, is mainly residual and formed by II clay has her,: (Brindley, et al., 1963). Very fine tubular the weathering of igneous rocks. Several de- is prepared fot structures commonly observable in electron posits in foreign countries are thought to have water, and it i\ micrographs of dehydrated halloysite (metahal- formed hydrothermally, and some are the re- Phelps, 197:i loysite) are ordinarily diagnostic of this min- sult of surficial weathering. .. manufacturin~ eral. -The shortcoming of this criterion 'is'-thaf Distribution of Deposits: United States- hod. not all metahalloysite occurs in ' the tubular Virtually all major productive halloysite de- ,ends: The pi<,. -form. A reliable criterion is that the basal posits in the United States have been referred ited States h.1, (001) spacing of halloysite is at approximately to in the foregoing discussions. Most of the he last sevcral 1OA; as halloysite converts irreversibly to meta- many other known scattered deposits are either s trend is forr. halloysite, the spacing collapses to about 7.2A, too small or too impure to he considered as likely to bc > which is essentially the same spacing^ as for significant sources of halloysite. Possible ex- ZOO0 (Coowr. kaolinite. Halloysite, therefore, can be identi- ceptions include the following: (1) the halloy- industry fnccr fied by the greater spacing in X-ray diffracto- site mixed with kaolin in weathered nepheline I sources. nnJ grams of samples containing natural moisture. syenite masses in the Arkansas bauxite region than import.. Nonclay minerals and other impurities in hal- (Gordon, et al., 1958); (2) the body of halloy- Tennessee an i 638 . ~. \ , . . -,. ;i These deposits are of several types, and they fractory clay is exported from the Peoples Re- :.:I blended to mak include transported, residual, and hydrother- public of China, which is apparently a major 2; product, and bli mally formed clay. Districts in which these producer. Fire clay is also mined in the USSR, 4 prepare differen scattered deposits occur include several areas in Czechoslovakia, Hungary, Poland, and other. , clays are ordina King County and the Castle Rock area in East European countries. . . . ' ,.,--.Tz,>*'+ products are pal ball clay is produced primarily in the western Mexico, Argentina, Brazil, Chile, Peru, Repub- truck. Heavy cr parts of Kentucky and Tennessee, but some of lic of South Africa, United Arab Republic.. _I required for ove the ball clay produced in Texas may be used in Australia, New Zealand, Iran. and other coun- I is ordinarily fire1 refractory products. tries, and most such deposits are no older than . -. . in both paper ba The total refractory clay. resources in the CretaGeous. ., ..' Future Consid United States suitable for 1ow:heat-duty refrac- Exploration and Evaluation: The method;' output of refrac tory products may be as much as 1 billion tons used in exploring and evaluating fire clay de- States was 1 I .S (Hosterman, 1973). However, the reserves- posits are in general similar to those used for tion has decreasi those clays that can be mined and processed bentonite and kaolin, except that different drill- versals of the tri now at competitive costs and are suitable for ing and testing procedures are required. Drill- the total refract1 low-heat-duty products or better-are probably ing fire clay deposits, particularly those of lion tons valuec no more than 1 billion tons. The reserves are Pennsylvanian age, ordinarily requires diamond This trend in dec primarily in the fire clay and refractory kaolin bits and core barrels of the type used for min- has been due ma and ball clay districts outlined previously. The erals in hard rock. This is because the clay (I) the develop remaining resources of high-grade diaspore clay itself and the rocks overlying the deposits arc nous refractory I are mainly under considerable overburden in hard. The most common test in the evaluation basic oxygen pro Pennsylvania, and only small resources are pres- of fire clay is the determination of PCE (pyrp quires basic raths ent in Missouri. The bauxitic kaolin resources metric cone equivalents, Table 4, p. 613). irfurnaces; (3) < are primarily in the Arkansas bauxite region, In addition to the PCE requirement, fired tal whereby fire cla and the Eufaula, Alabama, and Andersonville, pieces also may be tested for such properties as brick. stoneware. Georgia, districts. Some deposits also occur in high-temperature stability, hot strength, poror- classified as mix other parts of Alabama and Georgia. ity, and spalling (Anon., 1972h; Norton, 1968), clay. . Other Countries-Refractory clays are pro- Chemical analyses are. also required for Some The decrease ii duced in many countries; however, the informa- evaluations, and the contents of alkalies, alka- brought about b tion available to the authors on worldwide pro- line earths, iron oxides, and a few less common previous paragrai duction is sketchy and incomplete. This is elements are critical. because they act as flux= and markets for partly because the distinction between fire clay when clay refractories are heated; .-:. made from it cat and miscellaneous clay is not made in some Preparation for Markets: Fire clay and other sistently. Deman countries, and clay used for refractory prodocts refractory clays are mined by methods similar in the year 200 is lumped with kaolin in others. to those used for other types of clay. However. 17 million st (C, Those countries that produce more than a much higher percentage of fire clay mining The availobilit: I million tons of refractory (fire) clay annually in the past has been underground. The under- grade refractory include the United Kingdom, Federal Republic ground mining has been required because much one of the long- of Germany (West Germany), and Japan. The of the higher quality clay occurs at consider- refractories indu production in France exceeded a million tons a able depths, and the overlying rocks are.. '00. grade diaspore c few years ago but has apparently dropped be- hard to strip profitably. .. . souri that can bi low this figure in recent years. Other countries Firebrick and related products are prepared are nearing exhai producing 100,000 to 1 million tons annually for markets by grinding the clay, shaping Or ing increases cos include Argentina. Australia, India, Italy, forming the firebrick or other products, and fir- underground min Mexico, New Zealand, Sweden, the United ing. Commonly several varieties of fire clay the production c Arab Republic, Uruguay, and Yugoslavia. Re- and grog (crushed previously fired clay) arc olinitic clay has i Clays 639 Peoples R~. : blended to make a mix desired for a certain GA and Eufaula, AL, districts in recent years. -ntb a major - product, and blends are varied considerably to The trend for thr increasing use of these baux- in the USSR, prepare different grades of firebrick. The harder itic clays is expected to continue. Another 4 and other clays are ordinarily the most refractory, and as trend may be an increase in the heneficiation they lack plasticity, small proportions of kaolin of kaolin both to improve purity and to re- . clay in. other or plastic fire clay or both are added to aid in cover a coproduct, such as glass sand;to make deposits. Ka. , forming and bonding the brick until firing. the cost competitive. Kaolin and glass sand are 1 coalbeds 01 .-.Most firebrick is formed by hydraulic or other now produced as coproducts from impure de- : United King. I 'mechanical presses, but several types of prod- posits in Texas, Idaho. and Califor.nia. '.. ' of Germany, .. ucts are intricately shaped and must be formed hadiaspore. ' Miscellaneous Clay and Shale refractory ma. firebrick is fired in tunnel kilns heated Israel, and the .. by gas or oil. A few plants, particularly those Miscellaneous clay and shale includes a wide ractory kaolin making specially shaped products or having a variety of clay and other fine-grained rocks that Jngary, Italy, limited market, use downdraft kilns. Finished are used in many ways. Most products made 1, Yugoslavia, products are palletized and shipped by rail or from them are fired and include such things as Peru, Repub. truck. Heavy crating with padded packaging is structural and face brick, drain tile, vitrified TahRepublic. required for overseas shipments. Calcined clay pipe, quarry tile, flue tile, conduit, pottery, Id other twin. stoneware, and roofing tile. Very large ton- no older than nages of these materials are bloated by firing Future Considerations and Trends: The peak to form lightweight aggregate, and large quanti- The methods output of refractory (fire) clay in the United ties are used in making portland cement (see 3 fire clay de. s 11.8 million tons in 1957. Produc- the specific chapters in this volume). Uses not :hose used for requiring firing of a finished product include different drill- filler for paint and other products and shale quired. Drill. and clay used for packing dynamite in blast- arly those of holes and for plugging oil and gas wells that are luires diamond no longer in use. Adobe building blocks are used for min- also used in unfired form in several south- :ause the clay western states: le deposits arc the evaluation Properties ,f PCE (pyro. rather than alumina-type firebrick , p. 613). Clay and shale are used in so many different structural clay products that they necessarily ment, fired test have a wide range in physica1,properties. The h properties ar properties are plasticity, green strength,. dry trength, poros. strength, drying and firing shrinkage, vitrifica- *Torton. 196s) tion range, and fired color. The properties de- iired for some ase in demands for refractory clays sired vary with the structural clay product alkalies, aha- ut by the factors outlined in the made. For .example, a clay used in making v less common graph has probably bottomed out, conduit tile must be very plastic and have high :y act as fluxe, - and markets for refractory clay and products green and dry strengths and uniform shrink- made from it can be expected to increase con- age, but for drain tile or common brick these clay and other sistently. Demands forecast for refractory clay properties do not have to be controlled so tethods similar in the year 2000 are expected to be 12 to closely. :lay. However. 17 million st (Cooper. 1970). Most clays are plastic when naturally wet or re clay mininc The availability of high-grade and very high mixed with water. Plasticity can be defined as d. The under- grade refractory clays at competitive costs is the property of a material to undergo perma- because much one of the long-range problems faced by the nent deformation in any direction without 'UP- rs at considcr- refractories industry. Deposits of very high ture under stress beyond that of elastic yielding. rocks are 100 grade diaspore clay in Pennsylvania and Mis- Some clay materials are very plastic and are souri that can be mined by stripping methods called fot clay; others having little plasticity s are prepared are nearing exhaustion, and underground min- are called lean clay. The type of clay mineral, ay, shapins or ing increases costs considerably. The cost of particle size, particle shape, organic matter,' 0ducts;and fir- underground mining is one of the reasons why soluble salts, adsorbed ions, and the amount 2s of fire clay the Droduction of refractorv bauxitic and ka- and type of nonclay minerals influence the ired clay) arc plastic properties .~of clay. ~. 640 Industrial Minerals and Rocks Green-strength and dry-strength properties of Uniform color is an essential pro test pieces of spe( clay and shale are important because most many Structural clay products. The color of a . firing (Clews, 196 structural clay products are handled at least product is influenced by the state of oxidation felter and Hamlin. once and must be strong enough to maintain and particle size of the iron minerals; the firing ' tested for such pr shape. Green strength is the strength of the temperature and degree of vitrification; the .~ ing, cracking, perm clay material in the wet or plastic state. Dry portion of alumina, lime, and magnesia in the crushing or compr strength is the strength of the clay after it is clay material; and the composition of the gasa soluble salt contenl dried. Plasticity and green strength are closely in the kiln during the burning operation. High. products. related and are influenced mainly by the same grade white-burning clay contains less than 1% - Miscellaneous c variables. Dry strength is dependent on the Fe,O,, buff-burning clay ordinarily contaim open pits, Pits m proportion of fine particles present, the shape 1-5% Fe,O,, and red-burning clay contaim - digging must be c of the individual particles, the degree of hydra- 5% or more Fe,O,. Other constituents also material and finish the margin prc tion of the clay fraction, the method of form- affect the color, but finely divided iron-bearing ' - of ing the ware, and the rate and thoroughness of minerals generally are the principal products made fro the drying. The presence of a small amount of causing color in fired products. essed and . markei smectite, which occurs in very fine hydrated described for refra particles, generally increases dry strength. Occurrence _,. ,. Both drying and firing shrinkages are critical ' .-. .- - Future Consideratii properties of clay used for structural clay prod- Miscellaneous clay and shale occur in^ many ucts. Shrinkage is the loss in volume of a clay types of rocks'ranging in age from Precambrian The long-range I as it is dried or fired. Drying Shrinkage is de- lo Holoqene. They include glacial clay, soils. . products made fn pendent on the water content, the character of alluvium, loess, shale, weathered and fresh shale can be expe, the clay minerals, and their particle size. Most schist, slate, and argillite. Some fire clay and growth in the gror plastic clays shrink appreciably with drying, kaolin are also included in the miscellaneous mands for others a which tends to produce cracking and warping. clay group, particularly when used in the manu. growth rate. Dem, Sandy clay or clay having low plasticity has facture of structural-clay products. This group quired for portland low shrinkage properties but tends to produce consists of so many different types of rocks that gregate are increas a weak porous body. Smectite minerals in ra- only a few broad generalizations about their to continue. Thou: ther large amounts (10-25% ) commonly cause mineral makeup are possible. The most com- tural-clay 'products excessive shrinkage, cracking, and slow drying. mon mineral in many of them is one of the rials are facing stroi Firing shrinkage depends on the density of the members of the mica group, and the dominant wood, glass, plastic clay, volatile materials present, the types of one in a given deposit may be illite, sericite, or als. Growth in d crystalline phase changes that take place dur- one of the micas normally occurring in coarser products is also.har ing firing, and the dehydration characteristics of grain sizes, such as muscovite and biotite. In of these products, the clay minerals. addition to illite, the clay minerals present com- range, and by incre The temperature range of vitrification or monly are kaolinite, smectite, mixed-layer vp rise in fuel costs, glass formation during firing is a very impor- rieties, and chlorite, Some materials in this seems likely to be tant property of clay and shale used in struc- group actually contain more quartz and other the industry. . ~. tural clay products. Vitrification is a process of detrital minerals than clay minerals. .<.-: Another strong I gradual fusion in which some of the more easily Miscellaneous clay and shale are now mined' miscellaneous clay melted constituents produce increasing amounts in every state in the United States, except to rural areas. Fo of liquid as the temperature is increased. This Alaska and Rhode Island, according to us near population cei liquid produces glass as the material is cooled, Bureau of Mines Minerals Yearbooks. In 1980. tion costs. Suburb: and the glass is the bonding material in the final 32.4 million tons of these materials having a tion centers has fr fired product. Some clay has a shon vitrifica- value of $1 14.7 million was produced (Table 1). relocate because o tion range, and when such clay is fired the The states producing more than 1 million ton' raw-material supply temperature of the kiln must be very closely were Alabama, California, Georgia, Illinois. In- certain to continu regulated. Clay consisting chiefly of illite, diana, Iowa, Louisiana, Maryland, Michip, plants are in rural smectite, or chlorite has lower vitrification tem- Missouri, New York, North Carolina, ohto. to favor a substiti perature than kaolinite-rich clay. Some mineral Pennsylvania, South Carolina, Texas, and W- creased transportat. - impurities in clay, such as calcite and feldspar, ginia. Texas was the leading state in production in 1980, with 3.4 million tons, and North Caro- lower vitrification temperatures by acting as ' Government C. fluxes. The degree of vitrification attained also lina was second, with 2.8 million tons. . .-,. depends on the duration of firing and the tem- Bentonite and Kaol Testing, Processing, and Markets perature. Commonly the degree of vitrification . , . Most of the bent is regulated by the amount of shrinkage and The testing of miscellaneous clay and shale resources in the porosity needed in the final product. for most products requires the preparation Of domain lands. At 9' property test pieces of specific dimension. drying, and written, bentonite and kaolin deposits on fed- The color of firing (Clews, 1969; Grimshaw, 1972; Kline- eral lands for which mineral rights were not Le of oxidation feller and Hamlin. 1957). Fired test pieces are withdrawn or otherwise not obtainable were .=Is: the firing tested for such properties as shrinkage, warp- subject to the general mining laws. Mining lation: the pro. ing. cracking. permeability, modulus of rupture. claims could be filed on valid bentonite de- Wnesia in the crushing or compression strengths. Color and posits, and under certain conditions such claims on of the ease, soluble salt content are also important for some could be patented. The staking and patenting 'eration. High. products. of mining claims on public domain lands are 7 5 less than I 2 Miscellaneous clay and shale is dug from primarily under the jurisdiction of the Bureau larily contain, 'open pits. Pits must be near plants and the of Land Management, an agency of the US clay contain5 digging must be cheap, because both the raw Department of Interior. Further information 'nstituents a150 material and finished products are heavy, and on the staking and patenting of mineral claims :d iron-bearinp ' the margin of profit is ordinarily low. Most on federal lands can be found in Bureau of cipal material, : products made from these materials are proc- Land Management pamphlets 0-377-927 and ' essed and 'marketed much in the manner 0-3 77-93 0. i described for refractory clays. k Depletion Rates . Future Considerations and Trends Wrin many i The following depletion rates were in effect n Precambrian The long-range trends in demands for some in 1973 (Anon., 3972k): kaolin, ball clay, ial clay, soil,, products made from miscellaneous clay and bentonite, fuller's earth, and fire clay, 14% :ed and fresh shale can be expected to keep pace with the domestic and 14% foreign; clay and shale used : fire clay and growth in the gross national product, but de- for making brick, tile, and lightweight aggre- miscellaneou\ mands for others are likely lo fall short of this gate, 7%%, both domestic and foreign. The d in the manu. growth rate. Demands for clay and shale re- depletion rate for clay used for the extraction Is, This group quired for portland cement and lightweight ag- of alumina or aluminum compounds was set at :s of rocks thsl gregate are increasing, and this trend is likely 22%, but because'no clays have yet been used ns about thcir to continue. Though demands for heavy struc- for this puropse in the United States the rate 'he most coni- tural-clay products will continue, these mate- was not applied. is one of thc rials are facing strong competition from cement. I the dominant wood, glass, plastics. aluminum and.other met- Tariffs .ite, sericite. or als. Growth in demands for structural-clay ring in coarser products is also hampered by the heavy weight The statutory rates of duty per long ton for md biotite. In of these products, which limits their market the various classes of clay in effect in 1980 1s present coni- range, and by increasing production costs. .The, (Ampian, 1981) are listed in Table 5. lixed-layer c- rise iin fuel costs, which has been forecast, Nterials in thi, ... seems likely to be a major problem faced by Ecology art2 and othcr the industry. 11s. Another strong trend in the industry using All segments of the clay industry, like all ire now mined miscellaneous clay and shale has been the shift other mineral industries, face major problems States, exccpi lo rural areas. For a long time, plants were related lo the environmental controls, and com- 3rding to LS near population centers because of transporta- pliance with regulations now in effect has added OD~S.In 19SO. , tion costs. Suburban growth in many popula- significant production costs. Virtually all the major plants producing clay involving a dry- rials havin? 3 tion centers has forced plants to close or to iced (Table I ). relocate because of ecological pressures and grinding process have installed equipment to 1 million tons , raw-material supply problems. This trend seems control dust emissions in the atmosphere. Not ia, Illinois, In. certain to continue until virtually all active all such equipment has proved effective, and nd, Michigan. plants are in rural areas, which, in turn, tends some companies are faced with further expendi- arolina, Ohio. to favor a substitute material because of in- tures for improving dust control. The control exas, and Vir. creased transportation costs and other factors. of turbidity and other contamination in water : in production pumped from pits and discharged from wash- d North Cam ing and other types of plants is also required. - Government Controls and Influences tons. This regulation has forced mining to be shut = Bentonite and Kaolin on Public Domain Lands down at least temporarily in flooded fuller's earth pits and adds the costs of maintaining i Most of the bentonite and part of the kaolin settling ponds to remove the suspended mate- :lay and shale ources in the United States are on public rials in the discharge from kaolin-washing ?reparation of main lands. At the time this chapter was plants. As most clays are strip mined, land - -. - 642 Industrial Minerals and .Rocks 1 TABLE 5-Tariffs per Long Ton for Variws Classes of Clay. 1380 i.. ' : ,:+ +~j ., M. Kuzvart of C Rate of Duty (per Long Ton. $1 .. v ganized the Kai . ...I ,,~~. .; International Gel Item TSUS Number Most Favored Nation (MFN) Nan-MFN which much of -__ ' kaolin deposits 111181 1/1/87 . . ..: ;'iiimi . Ciudad Universi the AIPEA Mer China clay and kaolin 521.41 33.0$ 33.0g -._.-.- $2.50 provided inform Fuller's earth, not beneficiated 521.51 25.0$ 25.0$ .. ' 1.50 Spain. R. E. G Wholly or partly beneficiated 521.54 50.0$ 50.0$ ~.,.-3.25 manuscript and t Bentonite 521.61 40.0$ 40.0P . . 3.25 : gestions. K. Y. Ball clays. not beneficiated 521.71 41.0$ 38.0$ ..; .1.w - Wholly or partly beneficiated 521.74 ' 83.0.g 77.0$ . '.I :. . 2.00 a report on whk Other clays, not beneficiated 521.81 Free Free '.7'c''!.1.00 the Peoples Repi Wholly or partly beneficiated 521.84 50.0$ ' 50.0$ :.'.. .,. - . 2.00 1 ...... ,. -_ :1 Eibliogral, reclamation costs are now a major item. Com- 0. M. Wickem of Harhison-Walker; P. E. 'i monly, much as $500 per acre is spent as Turbett and H. C. Spinks of Clays Corp.: Anon., undated, in restoring mined bentonite lands in Wyoming, D. W. L. Spry, Clive W. Gronow, and.William Technical Bulle where the value for the surface alone is only Mallory of Anglo-American Clay Co.; James D. 15 PP. ahout one-tenth of that amougt. The restora- Cooper .and Sarkis G. Ampian of the US. Anon., 1952, Mar! tion of some of the strip-mined land in the frocrory Maren Bureau of Mines; Jack Rogers, E. E. Oxford. Society for Tesi Georgia kaolin belt costs as much as $800 per Tijs Volker, and Ralph B. Hall of I. M. Huber Anon., 1958. "Ble acre, hut the average cost is ahout $300 per Corp.; R. V. Colligan, Fred Gunn, H .H. Mor- Method. Cc 8a acre. The high costs of reclamation in Georgia ris. Paul Sennet, James Olivier, and Robert ciety. 2 pp. are due to state laws governing mining that Anon., 1959, "Ha Weaver of Freeport Kaolin Co.; Paul Thiele trict: Georgia are even more stringent than the federal and Owen Etheridge of Thiele Kaolin Co.: Geological Surr regulations. Wayne M. Bundy. John M. Smith, and Dora1 Anon., 1962, "Br: -Mills of Georgia Kaolin Co.; George Eusnei of p. 244. Anon.. 1962a. MG Acknowledgments Mulcoa-CE Minerals; R. E. Grim, University American Foun of Illinois; W. D. Keller and W. D. Johns, Uni- 619 pp. Much of the authors' knowledge of the vari- versity of Missouri; George W. Brindley and Anon., 1963, Fori ous clay industries has been gained by conver- Thomas F. Bates, Pennsylvania State Univer- American Foun 200 pp. .' sations and other communications with many sity: William F. Bradley and Edward Jonas! . Anon., 1964, "Ma professional and management personnel. Sev- University of Texas; C. E. Weaver and W. E. ' lacent Units in eral of these persons contributed to the infor- Moody, Georgia Institute of Technology; John Counties, Pen" mation required by one or both of the authors Koenig and Malcolm McLaren, Rutgers Uni- Pennsylvania GI for the preparation of this chapter, and others versity; N. 0. Clark and C. M. Bristow, English Anon., ,1965, "B . Trade Nora. I have aided them by contributing to their gen- China Clays; B. F. Buie, Florida State Univer- No. 4, pp. 12-14 eral background knowledge in the past. Among sity; and Walter Parham, Minnesota Geological .. Anon.. 1965a, "Ti those to whom we wish to express thanks are Survey. ern Bentonite." John McKenzie and Kefton H. Teague of Inter- Founder's Sociei Consulting geologists and engineers who have Anon., 1967, "Po national Minerals and Chemical Corp.; William assisted the authors in many ways include Information Cir. T. Granquist and John W. Jordon of NL In- Thomas L. Kesler, W. B. Beaty, Padriac Part. 148 pp. dustries; Arthur G. Clem and E. P. Weaver of ridge, E. W. Adams, Richard H. Olson, G. w. Anon., 1967a, ". American Colloid Inc.; W. L. Otwell, D. B. Phelps, William J. Lang, Richards A. Rowland. Minerals Yearb. Crosten, and E. ShuWebarger, Jr., of Penn- ofMines, p. 343 T. and Wayne Fowler. Anon., 1969, "AF sylvania Glass Sand Corp.; Finus Turner of The authors were also aided in the prepara- dard Procedure Dresser Magcohar; Jack W. Williamson, W. L. tion of this chapter by having access to infop API RP 13B, Haden, Jr., and T. D. Oulton of Engelhard mation gathered by John W. Hosterman (1973) Institute, 19 pp. Minerals and Chemicals Corp.; lames L. Rod. Anon.. 1969a. "i during the preparation of the clay chapter in an Drilling Fluid gers of Georgia-Tennessee Mining Co.; R. C. overall review of the mineral resources of the Valenta and Richard M. Jaffee of Oil Dri Corp. United States published by the US Geological of America; Robert P. Smith, Waverly Mineral Survey. E. C. Freshney of the U.K. Institute Of Products Co.; J. F. Bunt and Glen P. Jones of Geological Sciences supplied references to ma- General Refractories Co.; J. F. Wescott of terial on some of the clay deposits in'the United A. P. Green Refractories; Edward Ruh and Kingdom discussed in the previous pages, .. . ._. Clays 643 M. Kuzvarl of Charles University, Prague, or- Anon,, 1969d. “Buoyant Market for Ball Clays,” ganized the Kaolin Symposium at the 23rd lndirsfrial Miner&, No. 17, Feb., pp. 9-15. Anon., 1969e, “Erbsloh & Co.: Pioneer Pro- International Geological Congress in 1968 from ducer of Sodium-Exchanged Bentonite,” Indus- which much of the information on foreign rriol Minerals. No. 27, Dec., pp. 33-34. kaolin deposits was taken. Martin Vivaldi, Anon., 1969f, “Laporte’s Lead in Fuller’s Earth. Ciudad University, Madrid, Spain, organized Continued Expansion at Redhill.” Indusrrial the AIPEA Meeting of 1972 and personally Minerals, No. 24, Sep., pp. 15-16, $2.50 Anon., 19698, “National Lead Company, Huge provided information concerning the clays in Reserves Held by Baroid Division,” Indusrrial 1.53 Spain. R. E. Grim and B. F. Buie read the Minerals, No. 24, Sep., pp. 25-27. 3.25 manuscript and both made several helpful sug- Anon., 1969h, Review ond Forccosr, A Report 3.25 gestions. K. 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