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PLEASE DO NOT REMOVE FROM LIBRARY [RI[ 9028

Bureau of Mines Report of Inve.stigations/1986

Recovery of Fluorite and Byproducts From Fish Creek Deposit, Eureka County, NV

By F. W. Benn, D. G. Foot, Jr., and J. L. Huiatt

-/ I

UNITED STATES DEPARTMENT OF THE INTERIOR 1 1

Report of Investigations 9028

Recovery of Fluorite and Byproducts From Fish Creek Deposit, Eureka County, NV

By F. W. Benn, D. G. Foot, Jr., and J. L. Huiatt

UNITED STATES DEPARTMENT OF THE INTERIOR Don~ld Paul Hodel, Secretary

BUREAU OF MINES Robert C. Horton; Director Library of Congress Cataloging in Publication Data:

Benn, F. W. (Freddy W.) Recovery of fluorite and byproducts from Fish Creek deposit, Eur:eka County, NV.

(Report of investigations I United States Department of the Inte- rior, Bureau of Mines ; 9028) Bi bliography: p. 13.

Supt. of Docs. no.: I 28.~3:9028. 1. Fluorspar-Nevada-Eureka County. 2. Flotation. I. Foot, D. G. (Donald G.h II. Huiatt, J.~. III. Title: Report of investigations (United States. Bureau of Mines) ; 9028. I- TN23.U43 [TN948.F6] 6228 [622'.395] 86.600051 CONTENTS

Aba tract •••••••••••••••••••. fill ••• fill •••••••••••••••••••••• ,...... 1 Introduction .•..••••.••.•••.•..•.••••••.....••...... •••••.•••••••.•.••••••.•. 2 Experimental materials ••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 3 Experimental procedures and results •••••••••••••••••••••••••••••••••••••••••••• 4 Fluorite-beryllium sample •••••••••••••••••••••••••••••••••••••••••••••••••••• 4 Fluorite flotation ••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 4 Determination of preferred conditions •••••••••••••••••••••••••••••••••••• 4 Collector ••.••.•.•••••••••.•.•••..••.•••..••..• ., .•..••••.•..•.• • ' •.•...• 4 Flotation pH variation ••••••••••••••••••••••••••••••••••••••••••••••••• 5 Sodium carbonate ••••••••••••••••••••••••••••••••••••••••••••••••••••••• 5

Sodium silicate. 0·' •••••••••••••••••••••••••••••••••••••••••••••• I) ••••• a 6 Flotation under preferred conditions ••••••••••••••••••••••••••••••••••••• 6 Locked-cycle flotation testing ••••••••••••••••••••••••••••••••••••••••••• 6 Byproduct recovery ••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 7

Muscovi te removal ••••••••••• $ ••••••••••••••••••••••••••••••• •..••••••••• I) •• 7 addition ••••••••••••••••••••••••••••••••••••••••••••••••• 7 Collector addition ••••••••••••••••••••••••••••••••••••••••••••••••••••• 8 Silicate removal ....•.••.••••••..•.••..•....••••....•..•••...... ••••...•. 8 addition •••••••• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 8 Collector addition •••••••••••••••• ...... " ...... 9 Collector removal •.•••••.•••••••••.•..••••••••••••••••••••••••••••••••• 9 flotation •••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 9 Collector addition ••••••••••••••••••••••••••••••••••• ~ ••••••••••••••••• 9 Flotation under preferred conditions •••••••••• , •••••••••••••••••••••••• 10 Fluorite-mica sample ••••• ~ •••••••••••••••••••••• ,••••••••••••••••••• •••••••••• 10 Fluorite flotation ••••••••••••••••••••••••••••••••••••••••••• ~ • •••••••••••• 10 Determinatlon of preferred conditions •••••••••••••••••••••••••••••••••••• 11 Oleic acid conditioning time ••••••••••••••••••••••••••••••••••••••••••• 11 Flotation pH variation ••••••••••••••••••••••••••••••••••••••••••••••••• 11 Sodium silicate addition ••••••••••••••••••••••••••••••••••••••••••••••• 11 Flotation under preferred conditions ••••••••••••••••••••••••••••••••••••••• 12 Mi ca flo tation ••••••.••••••.•••••••••••••••••••••.•••••••••••••••••.•• ...... 12 Conclusions ••••••••••••.•••••••••••••••••.••••••••••• ., •••••••••••••••••••••••• ,_ 13 Ref erences ••••••.•••.•••••••.••••••••••••••••••••••••••••••• •- •••••••••••••••••• 13

ILLUSTRATIONS

Effect on fluorite grade and recovery, fluorite-beryllium sample: 1. Oleic acid addition •••••••••••••••••••••••••••••••••••••••••••••••••••••• 5

2. pH variation ..••.•••....••••••.•.••••••••.•••• 0_ ••••••••••••••••• " •••••••• 5 3. Na2 C03 addi t ••••••••.••••• \) ••.••••••••••••••••••••••••••••••..•.•••••• 6 4. Na2Si03 addition .•••.••••.•..•••••.••.•.•••••..•.••••....•.•••...... •.... 6

5. Flowsheet for concentrating beryl from CaF2 tailings product...... 7 Effect on BeO recovery and grade in muscovite rougher tailings: 6. H2 S04 addition •••••.•.•••.••.••••••••.•.•.••.•..•••• II •••••••••••••••••••• 8 7. Tallow amine acetate addition •••••••••••••••••••••••••••••••••••••••••••• 8 ii

Illustrations--Continued

Effect on BeO recovery and grade in silicate rougher concentrate: 8. HF add! t ion ••••••••• -...... , .••. 8 9. Tallow amine acetate addition •••••••••••• '•••••••••••••• '••••••••••••••••• 9

10. Effect of oleic acid addition on BeO recovery and grade in beryl rougher concentrate ••••••••••••••••••••••••••••••••••••••••••••••• ~ •••••• ~ ••••• 9 Effect of oleic acid conditioning time on flotation of fluorite-mica I~\ 11. ! sample· ••••••••••••••••••• ., ••••••• ,...... 11

Effect on fluorite grade and recovery, fluorite-mica sample: 12. pH variation ••••••••••••.. ill ••••••••••••••••••••••••••••••••••••••••••••• 11 13. Na2Si03 addition •••••••••.•••.•.•••.••••....•....•.•...•...•..••.•.•..•• 12 'I TABLES

1- Chemical analyses of Fish Creek samples ••••••••••••••••••••••••••••••••• 3 2. Screen analysis of fluorite-beryllium sample •••••••••••••••••••••••••••• 3 3. Screen analysis of fluorite-mica sample ••••••••••••••••••••••••••••••••• 4 4. Preferred reagent dosages for byproduct recovery from fluorite-beryllium sample ...... 10 5. Fluorite and byproduct flotation from fluorite-beryllium sample under preferred conditions ••••••••••••••••••••••••••••••••••••••••••• ~ ••••••• 10 6. Rougher flotation results for fluorite-mica sample using different

collectors ...... 0 •• , •••••• 11 7. Fluorite and mica flotation from fluorite-mica sample ••••••••••••••••••• 12

UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT

g gram min minute

lb pound pct percent

lb/st pound per (short) ton st short ton (U.S.)

micrometer wt pct weight percent RECOVERY OF FLUORITE AND BYPRODUCTS FROM FISH C~EEK DEPOSIT, EUREKA COUNTY, NV

By F. W. Benn,l D. G. Foot, Jr.,2 and J. L. Huiatt 3

ABSTRACT

The Bureau of Mines investigated flotation methods for recovering fluorite and byproducts from two samples of the Fish Creek deposit in Eureka County, NV. The preferred method for tre.ating a fluorite­ beryllium sample included (1) fluorite rougher and cleaner flota­ tion, (2) desliming at 20 ~m, (3) muscovite flotation, (4) silicate flo­ tation, (5) sodium hypochlorite wash of silicate concentrate, and (6) beryllium rougher and cleaner flotation from the silicat.e concen­ trate. Laboratory results showed that over 94 pct of the fluorite was recovered in a recleaner concentrate containing 98 pct CaF2 , Beryllium flotation produced concentrates containing in excess of 5 pct BeO with recoveries over 70 pet. The preferred method used for a fluorite-mica sample consisted of (1) fluorite rougher and cleaner flotation, (2) desliming at 20 ~m, and (3) mica flotation using an anionic-cationic collector system. Labora­ tory results showed that 84 pct of the fluorite was recovered in a re­ cleaner concentrate containing' 96 pct CaF 2 , Mica flotation produced a concentrate containing 95 pct mica at 85-pct recovery.

Minerals engineer. 2Group supervisor. 3Research supervisor. Sal t Lake Ci ty Research Cen ter, Bureau of Mines, Salt Lake Ci ty I UT.

I .. If I' ---;~-;:~ . ., i

2

INTRODUCTION

Fluorspar is the commercial name for an highest price. Major uses include the aggregate of rock and matter con­ manufacture of chemicals, syn­ taining a sufficient amount of the min­ thetic (essential for aluminum eral fluorite (CaF 2) to qualify as a production), preservatives, insecticides, marketable commodity. Pure fluorite is aerosols, and metal coatings. , which contains 51.3 pct Domestic shipments of finished fluorite Ca and 48.7 pct F. Fluorite is the prin­ declined for the third consecutive year cipal source of fluorine, an element for in 1984. Fluorite output failed to ex­ which no adequate substitute has been ceed 100,000 st for only the fourth time found. Fluorite is used principally as since 1938. Mexico remained the major a fluorine source in the making of supplier of metallurgical- and acid-grade (1) hydrofluoric acid (HF), (2) a in fluorite (54 pct), with the Republic of metallurgy, and (3) a raw material in the South Africa the second largest supplier manufacture of and enamels. (28 pct). Minor amounts were received Fluorite is marketed in three grades from China, Italy, , and Kenya (2). that have different physical and chemical A long-term downward effect on the-de­ specifications (1):4 mand for fluorite and fluorine compounds continues, as steelmakers consume less Metallurgical grade.--This is also fluorite per unit of output and primary known as "metspar" or "lump and aluminum smelters adopt and refine tech­ is sold on the basis of effective CaF2 nology that recovers and recycles more content rather than the actual CaF2 fluorine. New and expanded uses for flu­ content. The effective CaF2 content is orine chemicals will offset these de­ derived by subtracting 2.5 times the creases in long-term demand. From a 1985 percentage of the silica (Si02) content base, consumption of fluorite equivalent from the percentage of CaF 2 content. is . expecte(r~to-increase at an annual "Metspar" users require 60 to 70 pct average rate of 2.7 pct through 1990 (2). effective CaF 2 , limit Si02 to 5 or The long-term U.S. fluorite requirements, 6 pct, limit sulfides to under 0.50 pct, of which 91 pct is imported, will have to and limit to under 0.25 pct. Metal­ be derived from secondary sources, sub­ lurgical-grade fluorite is used as a flux marginal domestic ores, or multicomponent in , as an electrolyte in aluminum ores (2). , and in metal welding, porcelain Most- domestic fluorite is produced enameling, and glazing. in the Midwest. Production in Illinois Ceramic grade.--This is also known as accounts for over 90 pct of all U.S. "glass" and "enamel" grade and must con­ shipments. In the West, production was tain a minimum of 95 pct CaF 2 , with a reported from small mines in Nevada and maximum of 2.5 pct Si02 • It must be fine Texas. Small, unreported amounts of flu­ grained for use in the manufacture of orite were produced in Utah, Idaho, and opaque and , as an ingredi­ New Mexico (3). Approximately 90 Nevada ent in welding and coatings, in making deposits containing 5 to 50 pct CaF2 , white- and buff-colored clay bricks, and with byproducts of barite, beryllium, in vitreous enamels for coating metal ar­ , zinc, , and , were ticles and appliances. reported (4-5). Byproduct recovery is Acid grade.--This is used in the man­ necessary to-enable economic processing ufacture of HF and should contain a mini­ of submarginal domestic reserves. mum of 97 pct CaF2 and not over 1.1 pct Traditional methods of concentrating Si02 , 1.25 pct CaC0 3 , and 0.03 pct S. fluorite use gravity separation, followed Acid-grade fluorite is the highest qual­ by flotation. A flotation procedure us­ ity marketed and therefore commands the ing oleic acid as a fluorite collector was patented (l) and used to recover 4Underlined numbers in parentheses re­ acid-grade fluorite from an Illinois fer to items in the list of references at jig tailings that contained 44 pct the end of this report. CaF2 • Another procedure, which depressed 3

barite with lignin sulfonate and floated beneficiation methods to recover fluo­ fluorite with oleic acid, was used to rite, muscovite, and beryllium values beneficiate a Yuma County, AZ, fluorspar from the Fish Creek deposit in Nevada. ore (7). The Bureau of Mines charac­ This report summarizes the results of terized and devlsed new flotation that investigation. EXPERIMENTAL MATERIALS Two samples were obtained 'from the Fish Petrographic analyses of the fluorite­ Creek fluorspar deposit near Eureka, NV. mica sample indicated that it contained One sample was known to contain beryllium major amounts of fluorite, , chert values. The samples were crushed and (microcrystalline quartz), muscovite, bi­ screened through 10 mesh and thoroughly otite (black mica [(K,H)2(Mg,Fe)2(Al,Fe)2 blended, after which representative por­ (8i04 )3])' and phlogopite (magnesium mica tions were submitted for chemical and [(K,H)3Mg3Al(Si04)3])' Minor amounts of petrographic analysis. The chemical an­ pyrite (FeS2), , limonite, potas­ alyses are shown in table 1. sium-, cal.cite, serpentine [Mg3 Petrographic analysis of the fluorite­ (Si05 )(OH)4]' apatite. (CaFP30,2 ), schee­ beryllium sample indicated that it con­ l,ite (CaW04), , smithsonite tained major amounts of quartz (8i02), (ZnC03), Willemite (Zn2Si04)' franklinite fluorite (CaF 2), and muscovite (light­ [(Fe,Mn,Zn)(FeOZ)2], an unidentifiable colored mica [KAl 38i30 I0 (OH)2])' Minor zinc-iron mineral, chlorite, and kaolin­ Ii amounts of hematite (Fe203)' limonite ite (Al203'2Si02'2HzO) were observed. (hydrous iron oxides), sphalerite (ZnS), Liberation size was 35 mesh. :1 iI­ potassium-feldspar (KAl8i308 ), beryl Minus 35-mesh material was prepared for (Be3Al2Si6018)' (CaC03), and bench-scale testing by stage crushing r chlorite (hydrous silicates of aluminum, through a jaw and roll crusher and then ;1 i ferrous iron, and magnesium) were ob­ pulverizing. Each ore was blended and served. Liberation size was 35 mesh. split into 500-g samples. A screen an­ I alysis was performed on the minus 35-mesh TABLE 1. - Chemical analyses of samples to determine the distribution of Fish Creek samples, percent the fluorite and/or beryllium (tables 2 I and 3). Only. 3.2 pct of both fluorite Chemical composition and beryllium (BeO) values reported to Constituents Fluorite- Fluorite- the minus 400-mesh fraction of the beryllium mica fluorite-beryllium sample; about 83 pct BeO...... 0.54 0.03 of the CaF2 and BeO reported to the minus CaC0 3••••••••••••• ·.8 2.U 35- plus 400-mesh fraction. Similarly, CaF 2•••••••••••••• 10.5 27.1 the minus 400-mesh fraction of the Si02 •••••••••••••• 82.6 54.4 fluorite-mica sample contained 13.7 pct Zn...... 3 .2 , of the fluorite; nearly 73 pet of the Total Fe...... 1.2 1.3 fluorite was contained in the minus Total mical ••••••• 4.0 15.0 35- plus 200-mesh fraction. lEstimated by petrography.------~----~---

TABLE 2. - Screen analysis of fluorite-beryllium sample, percent

Size, mesh Weight Analysts Distribution CaF2 BeO CaF2 BeO -35, +48,. •••••••••••••••• 15.4 8.3 0.58 12.2 16.4 -48, +65 ••••••••••••••••• 18.8 9.7 .61 17.4 21.1 -65, +100 •••••••••••••••• 24.0 15.2 .65 34.7 28.8 -100, +200 •••••••••••••••• 19.1 10.3 .49 18.7 17.2 -200, +325 •••••••••••••••• 10.3 8.6 .43 8.4 8.1 -325, +400 •••••••••••••••• 7.5 7.6 .38 5.4 5.2 -400 •••••••••••••••••••••• 4.9 6.8 ,36 3.2 3.2 Composite •••••••••••• ! •••• 100.0 lO.. 5~1 .51. 100.-0 lOO.O 4

TABLE 3. - Screen analysis of fluorite-mica sample, percent

Size, mesh Weight CaF2 Analysis Pistribution -35, +48 ...... 12.2 29.8 l3.4 -48, +65 ...... 15.0 28.7 15.8 -65, +100 ••••••••••••••••• 17.1 28.9 18.2 -100, +200 ••••••••••••••••• 22.4 30.9 25.7 -200, +325 ••••••••••••••••• 11.5 29.2 12.4 -325, +400 ••••••••••••••••• .8 28.0 .8 -400 ••••••••••••••••••••••• 21.0 17.7 13.7 Composite •••••••••••••••••• 100.0 27.1 100.0

EXPERIMENTAL PROCEDURES AND RESULTS

Conventional gravity separation tech­ 4. Adjusting pulp to desired pH level. niques, such as tabling, jigging, and 5. Conditioning with food-grade oleic heavy-medium separation, were investi­ acid at desired pH. gated to concentrate the fluorite. 6. Rougher flotation for 5 min. Some upgrading was achieved, but these methods did not produce concentrates of Determination of Preferred Conditions sufficient grades or recoveries. proved to be the most Collector successful. A Denver D-1 5 laboratory flotation machine was used in the flota­ Based on tests varying the oleic acid tion testwork. dosage from 0.5 to 3.0 lb/st, a preferred dosage of 2.0 lb/st was determined. In FLUORITE-BERYLLIUM SAMPLE these tests, flotation pH was held at 9.0, and dosage levels were 3 lb/st Fluorite Flotation NazC03 and 2 lb/st Na2Si03.6 As shown in figure 1, highest recovery (97 pet of the Flotation testing was performed to de­ CaFz) was at the 2-lb/st addition level. termine the effects of fluorite rougher Grade peaked at a slightly lower dosage flotation of (1) collector addition and level; however, in rougher flotation , conditioning time, (2) flotation pH vari­ higher recovery is worth a slight trade­ " "j . ;1 ation, (3) sodium carbonate (Na2C03) ad­ off in grade • ],1 dition and conditioning time, and (4) Based on tests varying the oleic acid sodium silicate (Na2Si03) additi9n and conditioning time (CT) from 3 to 30 min, conditioning time. As in the prior pro­ a preferred time of 15 min was deter­ cedures (6-7), food-grade oleic acid, a mined. In these tests, conditioning time mixture of-oleic (72 pet), linoleic, lin­ was held at 3 min each for Na2C03 and olenic, and rosin acids, was used as the Na2Si03, and dosage levels were held collector. Tests were conducted varying at 3 lb/st for both Na2C03 and Na2Si03 each factor to determine the optimum, or and at 2 lb/st for oleic acid. While "preferred," flotation conditions. recovery showed a continual slight in­ The generalized procedure for fluorite crease (from 95.2 pet at 3 min to 98 pet flotation consisted of-- at 30 min oleic acid CT), grade in­ I. Pulping ore and water at 50 pet creased from 65.5 pet CaF2 at 3 min CT . to 72.8 pct at 15 min CT, then fell to 2. Conditioning with Na ZC03• 70.4 pet at 30 min CT. 3. Conditioning with Na zSi03•

5References to specific products does 6This was lower than the preferred do­ not imply endorsement by the Bureau of sage of 3 lb/st for NaZSi03, which had Mines. not ye t been de termined. 5

100 ,using NaOH or HCl to vary pH from 7 to 11, a preferred pH of 9.0 was Recovery determined. In these tests, conditioning times were 90 held at 3 min for each reagent! as pre­ I- liminary data had indicated that the Z general effect of pH changed very little t5 80 0:: with longer times. Reagent dosages were w Grade Q. held constant at 3 lb/st Na2C03 and 2 lb/st each for NazSi03 and oleic acid.7 70 As shown in figure 2, maximum grade was achieved at a pH of 9.5, whereas recovery began to fall sharply above pH 9, tho~gh

60L-----~----~----~----~--~ rising again above pH 10. At the prefer­ 0.5 1.0 1.5 2.5 3.0 red flotation pH of 9.0, 94.6 pct of the OLEIC ACID ADDITION, Ib/st fluorite was recovered in a rougher con­ centrate of 79.3 pct CaF2 ; this pH level FIGURE 1. - Effect of oleic acid addition on fluorite was 'considered the best compromise be­ grade and recovery, fluorite .. bery II ium sampl~. tween grade and recovery.

Sodium Carbonate 100 Sodium carbonate (Na2C03) was used as a 90 water cqnditioner and to aid in gangue depression. Based on tests varying do­ 80 sage levels from 0.5 to 4 Ib/st, a pre­ ferred dosage of 3 lb/st was determined. ~ 70 In these tests, flotation pH was held w u at 9.0, CT for all reagents was 3 min, a:: and dosage levels were 2 lb/st for both ~ 60 Na zSi03 and oleic acid. As shown in figure 3, recovery was nearly constant, 50 while maximum grade of 73.2 pct CaF2 was at 3 lb/st Na2C03' above which level 40 gangue flotation caused a dropoff in grade. 30 Based on tests varying NazC03 condi­ 7.0· 8.0 9.0 10.0 11.0 tioning time from 3 to 30 min, a prefer­ pH red time of 15 min was determined. In FIGURE 2~ - Effect of pH variation on fluorite grade these tests, CT was held at 3 min each and recovery, fluorite-beryl I ium sample. for NazSi03 and oleic acid, and dosage levels were held at 3 lb/st for NazC03 Flotation pH Variation and 2 lb/st for both NazSi03 and oleic aCid;8 flotation pH was 9.0. Recovery Prior investigators (8-9) reported held near constant at 97 pet, while grade that the point-of-zero-charge for fluo­ had slight fluctuation from 78.5 pct CaF2 rite was at pH 10.0; therefore, the pH at 3 min CT to 82.5 pet CaFz at CTr s of for fluorite flotation using an anionic 15 min and longer. collector should theoretically be below pH 10, owing to the positive charge 7See footnote 6. on the fluorite surface. Based on tests 8See footnote 6. 6

as a quartz- and silicate-mineral depres­ lOOt Recovery sant. Based on tests varying dosage j levels from to 4 lb/st, a preferred 90 ° Grade dosage of 3 lb/st was determined. In 70 these tests, flotation pH was 9.0, CT for I­z w all reagents was 3 min, and dosage levels o were 3 lb/st for Na2C03 and 2 lb/st ffi 60 0... for oleic acid. As shown in figure 4, recovery dipped slightly between dos­ 50 age levels of 1.5 and 2.5 lb/st Na2Si03' then increased toward 100 pct above that level. Grade, on the other hand, 1.0 1.5 2.0 2.5 3.0 3.5 4.0 showed sharp increases up to addition SODIIJM CARBONATE ADDITION, Ibis! levels of 3 lb/st Na2Si03' then dropped FIGURE 3.· Effect of Na2COa addition on fluorite off because of increased gangue grade and recovery, fluorite-beryllium sample. flotation; Based on tests varying Na2Si03 con­ ditioning time from 3 to 30 min, a pre­ ferred time of 15 min was determined. In these tests, CT was held at 3 min 10°F===~==r---~--~--~~1 each for Na2C03 and oleic acid, and do­ sage levels were held at 3 lb/st for Recovery Na2C03 and 2 lb/st for both Na2Si03 and 90 oleic acid;9 flotation pH was 9.0. Re­ covery held constant at approximately 80 95 pct, while grade increased from 65.5 pct CaF2 at 3 min CT to 80.4 pct at 15 min CT, then df-opped to 72 pct at I- 70 30 min CT because of increased gangue z w flotation. U 0:: ~ 60 Flotation Under Preferred Conditions

Under preferred conditions--3 lb/st 50 Na2C03' 3. lb/st Na2Si03' and 2 lb/st oleic acid; 15 min CT for each reagent; and flotation pH of 9.0--a fluorite 40 rougher concentrate . containing 83 pct CaF2 was produced with 96.1-pct fluorite recovery. This concentrate was cleaned 30~--~----~----L---~----~--~ 0.5 1.0 1.5 2.0 2.5 3.0 3.5 twice without additional reagents other SODIUM SILICATE ADDITION, Ib/st than those needed to maintain the pH level; the second cleaner concentrate FIGURE 4 •• Effect of Na2Si03 addition on fluorite contained 98.1 pct CaF2 with a recovery grade and recovery, fluorite~beryllium sample. of 94 pct.

Locked-Cycle Flotation Testing

Sodium Silicate Locked-cycle flotation testing was performed to determine the \ effects of I' Sod~um silicate (Na2Si03), with a Si02-Na20 wei~ht ratio of 3.22, was used 9see footnote 6. 7

recycling the cleaner tailings products -35 mesh feed and recycling water on fluorite flota­ tion. This process was' also used to ob­ tain data for scale-up planning. The Fluorite flotation Fluorite concentrate cleaner tailings and recieaner tailings were combined and scavenged, with the Tailing$ scavenger concentrate being recycled to the head of the next cycle. The fluorite Deslime at 20}Jm Slimes r6ugher tailings were combined with the scavenger tailings to make the final tailings. Five complete cycles were per­ formed to assure the system was in equil­ Muscovite flotation Muscovite concentrate ibrium. All water was recycled except the rougher tailings water. Fluorite re­ Tailings covery was 94 pct at a grade of 96 pct CaF • The final tailings contained over 2 Silicate flotation Tailings (free silica) 90 pct of the weight, with a grade of 0.62 pct CaF 2 , representing a loss of 5.78 pct of the fluorite. The concen­ Concentrate trate contained 0.01 pct BeO, while the tailings product contained over 99 pct of Collector removal the BeO values with a grade of 0.60 pct BeO.

Byproduct Recovery Water wash

Various procedures were investigated to concentrate the beryl. The preferred Beryl flotation Beryl concentrate method consisted of (1) fluorite flo­ tation using oleic acid, (2) desliming at 20 ~m, (3) muscovite flotation using Beryl tailings H2 S04 and tallow amine acetate, (4) sili­ cate minerals flotation using HF and tal­ FIGURE 5. - Flowsheet for concentrating beryl from low amine acetate, (5) collector removal CaF 2 tailings product. from the silicate concentrate using NaOCl, (6) water washing of the silicate the flotation products. Preferred con­ concentrate, and (7) beryl flotation from ditions were based on (1) the percent BeO the silicate concentrate using oleic values in the muscovite flotation pro­ acid (10)., The flowsheet is shown in ducts, (2) the BeO grade of the muscovite figure s:- tailings, and (3) total weight removed from the deslimed fluorite tailings Muscovite Removal product.

Flotation testing was performed on Sulfuric Acid Addition the muscovite flotation circuit to determine the effect of (1) H2 S04 addi­ Sulfuric acid (H2 S04 ) was used as the tion and (2) collector (tallow amine ace­ pH modifier and as the beryl depressant. tate) addition. The muscovite had posed Based on tests varying H2 S04 dosage a problem in previous testwork because from 1 to 4 lb/st, a preferred dosage of it would concentrate with the beryl, '3 1b/st was determined. In these tests, thus lowering the beryl concentrate CT for both reagents was held at 3 min, grade. No reliable analytical method was and dosage for tallow amine acetate wa~ available for determining muscovite in 0.3 Ib/st. As shown in figure 6, overall 8

IOO~--~-----.----~--~-----r----. beryl recovery increased slightly with increasing H2S04 , while the beryl content Recovery in the muscovite tailings was highest at t 90 approximately 3lb/st H2 S04 - In addi­ Q. tion, at this preferred dosage the maxi­ >-" mum weight was removed from the muscovite ffi 80 ~0.8 0 Q) concentrate, at pH 3. § Grode In 0:: 8. 70 .7 ~ Collector Addition «~ 0:: Based on tests varying collector (tal­ .6 (!) 1.5 2.0 2.5 3.0 3.5 4.0 low amine acetate) dosage from 0.3 to SULFURIC ACID ADDITION, Ib/st 1 lb/st, a preferred dosage of 0.7 lb/st was determined. In these tests, CT was FIGURE 6 •• Effect of H2SO .. addition on BeO held at 3 min for both reagents, and recove.ry and grade in muscovite rougher tail ings. H2 S04 dosage was held at 2 lb/st; pHwas held at 3. As shown in figure 7, over­ all beryl recovery fell slightly with increasing collector dosage, while the beryl grade of the muscovite tailings was t; 90 ~-----RD:e;;;c~ov:;;;e:;'ry:;------J highest at 0.7 lb/st collector; at that Q. >-" dosage also the maximum weight was re­ ffi 80 0.8 ~ moved from the muscovite concentrate. In 8 Grade t; 0- ~ 70 .7 W- Silicate Removal «o 60 J,...... __---L- __--L ____ l....- __~ ___L __ ___1 ______' .6 ffi Direct flotation of beryl produced con­ 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 centra·tes with~grades less than 2 pct TALLOW AMINE ACETATE ADDITION, Ib/st BeO; therefore, silicate flotation was used to depress the free Si0 and improve FIGURE 7. - Effect of tallow amine acetate addi­ 2 tion on BeOrecovery and grade in muscovite rougher the grade prior to beryl flotation. Flo­ tation testwork was performed on the sil­ tail ings. icate flotation circuit to determine the effects of (1) HF addition and (2) col­ lector (tallow amine acetate) addition on the flotation of the silicate (beryl and feldspar) minerals.

70 Hydrofluoric Acid Addition t; 60 Cl. Hydrofluoric acid '(HF) was used as an >-" 50 0:: activator for the beryl, as a quartz de­ W pressant, and as a pH modifier. Based ~ 40 o on tests varying HF dosage from 0 to ~ 30 10 lb/st, a preferred dosage of 5 lb/st ui was determined. In these tests, the pulp 20 2 0 was first conditioned with HF for 3 min, ~ 10 r{!) then with 1 lb/st collector for 3 min, after which the silicates were floated. 0'----""-----'----'------'------' 0 . As shown in figure 8, both recovery an9 2.0 4.0 6.0 8.0 10.0 grade increased with increased HF addi­ HYDROFLUORIC ACID ADDITION, Ib/st tion up to about 5 lb/st, then fell FIGURE 8. - Effect of HF addition on BeOrecov­ sharply with further HF additions; gangue ery and grade in s i I icate rougher concentrate. flotation caused the ,fall in grade, while

I

·1 : i 9

reagent bui~dup on the beryl' surface depress gangue flotation in the beryl lowered the recovery. At 5 lb/st HF ad­ circuit, which would lower the beryl . dition, concentrate grade was 4.80 pct grade. To accomplish this, the pulp was BeO with a recovery of 89 pct; pulp pH washed for 5 min with 2 lb/st NaOCI, then was 2.75 at this preferred dosage. allowed to settle for another 5 min. The excess liquid was decanted and Collector Addition the solids repulped with fresh water. ! Then the pulp was conditioned for 5 min I ,~ The- collector, tallow amine acetate in and allowed to settle for another 5 min a 5-pct solution, was used to separate before the excess fresh water' was the silicate minerals from the free 8i02 • decanted. Based on tests varying collector dosage from 0 to 5 lb/st, a preferred dosage Beryl Flotation of 0.5 lb/st was determined: In these tests, the pulp was conditioned with Testwork had indicated that beryl the collector ,following conditioning selectivity could be improved by using for 3 min with 5 lb/st HF. As shown in aflotat!on pH of 11.0. Flotation test­ figure 9, grade decreased steadily with work was thus performed to determine increasing amounts of tallow amine ace­ the optimum (preferred) amount of collec­ tate, whereas recovery jumped sharply tor needed for beryl flotation at this with as little as 0.5 lb/st collector, pH. then continued to increase gradually before falling off slightly at dosage Collector Addition levels above 3 lb/st. At 0.5 lb/st col­ lector, concentrate grade was 4.55 pct Food-grade oleic acid was used as the BeO with a recovery of 81 pct. collector for the beryl. Based on tests varying dosage from 0.3 to 1 lb/st, a Collector Removal preferred dosage of 1 Ib/st was deter­ mined. In these tests, pH was held con­ Sodium hypochlorite (NaOCloSH2 0) was stant at 11, and conditioning time at used to remove the collector from the 3 min. As shown in figure 10, the beryl mineral surfaces in order to gain selec­ tivity in the beryl circuit. Removal of 70 ,..------r---...,....,...-----,---; residual collector was necessary to

90 60

80 8 +- 50 5 (.) Q. 70 7 Grade U >-"40 4 0 a. 60 60 a::: (j) -ft co ffi 50 5 t 630 31:) > Q. &3 Q. 840 4w w 0 a::: 20 0:: « 30 315 10 20 2

o I~ __---L ___ __'______L_ _ ___l 0 10 I o I ,0 2,0 3,0 4.0 5.0 0.3 0.5 0.7 0.9 1.0 TALLOW AMINE ACETATE ADDITION, Ib/st OLEIC ACID ADDITION, Ib/st FIGURE 9, • Effect of tallow amine acetate addi­ FIGURE 10. -Effect of oleic acid addition on BeO tion on BeO recovery and grade in s i I icate rougher recovery and grade in beryl rougher concentrate. concentrate, rougher· grade reached a maximum of FLUORITE-MICA SAMPLE 4.15 pct BeD at 0.6 1b/st, then decreased slightly with increased additions. Re­ Fluorite Flotation covery, however, increased steadily with increasing collector addition. Additions Flotation tests were performed to higher than 1 Ib/st caused increased gan­ determine the effects of (1) collector gue flotation and thus a significant drop addition and conditioning time, (2) flo­ in grade. tation pH variation, and (3) Na2Si03 ad­ dition! Three collectors were evaluated, Flotation Under Preferred Conditions each at a single dosage level (table 6): Pamak 4A, a mixture of 50 pct oleic Under the preferred flotation con­ acid and 50 pct linoleic acid; Aero 830, ditions (table 4), a rougher beryl con­ which is modified petroleum sulfonate; centrate was produced that contained and food-grade oleic acid. Though re­ 75.3 pct of the beryl at a grade of covery was slightly lower with the oleic 5.45 pct BeD. An initial cleaner concen­ acid, the much higher grade of 77.2 pct trate contained 54 pct of the beryl at CaF2 showed it to be far more selective a grade of 6.11 pct BeD; after a second than the other co~lectors. Overall, flu­ cleaning, recovery was 37.3 pct at a orite rougher concentrate grades were grade of 6.73 pct BeD. This is close to somewhat lower for the f1uorite-mica the minimum acceptable grade for further sample than for "the fluorite-beryllium processing of 7 to 8 pct BeD. Flotation sample; this W,as attributed to a higher results are summarized in table 5. slime content.

TABLE 4. - Preferred reagent dosages for byproduct recovery from fluorite-beryllium sample

Flotation stage Reagent Dosage, 1b/st Muscovite flotation ••••••••• Sulfuric acid •••••••• 3.0 Tallow amine acetate. .7 ii"~ ..

···1' Silicate rougher flotation •• Hydrofluoric acid •••• 5.0 h i-Ij Tallow amine acetate. .5

Collector removal ••••••••••• Sodium hypochlorite.. 2.0

Beryl rougher ••••••••••••••• Oleic acid...... 1.0

TABLE 5. - Fluorite and byproduct flotation from fluorite-beryllium sample under preferred conditions, percent

Product Analysis Distribution CaF2 BeD CaF2 BeD CaF2 cleaner concentrate ••••••••••••••• 198.1 < 0.01 94.0 1.6 Slimes. 0 ...... 3.4 .20 2.7 1.4 Muscovite concentrate •••••••••••••••••• 2.4 .12 1.5 2.2 Silicate tailings •••••••••••••••••••••• .1 .02 .9 3.8 Beryl rougher concentrate •••••••••••••• .8 5.45 .7 75.3 Beryl tailings ••••••••••••••••••••••••• .4 .83 .2 15.7 1 Sulfide, lead, and silica assays are below product specification level for acid-grade fluorite. 11

TABLE 6. - Rougher flotation results for Flotation pH Variation fluorite-mica sample using different collectors Based on tests varying pH from 7 to 10.7, a preferred pH of 9.0 was deter­ Reagent Dosage, Grade, Recovery, mined. In these tests, CT was 3 min for lb/st pct CaF2 pct both reagents, and dosage was 2 lb/st for t Pamak 4A •••• 2.0 56.0 97.9 Na2Si03 and 1.5 lb/st for oleic acid. As Aero 830., ••• 2.0 56.4 93.6 shown in figure 12, recovery decreased 1 very gradually until the pH reached 10, I Oleic acid •• 1.5 77 .2 92.2 then fell very sharply, while grade con­ Determination of Preferred Conditions tinued to increase with increasing pH level. At pH 9, grade was 75 pct CaF2 Oleic Acid Conditioning Time with a recovery of over 90 pet.

Based on tests varying oleic acid con­ Sodium Silicate Addition ditioning time from 3 to 30 min, a pre­ ferred time of 10 min was determined. Na2Si03 was used in ,the fluorite cir­ In these tests, conditioning time was cuit as a quartz depressant. Based on held at 3 min for Na2Si03, and dosage tests varying dosage from 1 to 4 lb/st, levels were 2 lb/st Na2Si03 and 1.5 lb/st a preferred dosage of 2 lb/st was deter­ oleic acid; flotation pH was 9.0. While mined. In these tests, oleic acid do­ recovery increased steadily with increas­ sage was held at 1.5 Ib/st, and CT was ing conditioning time (fig. 11), grade 3 min for both reagents. As shown in was highest at 10 min CT before fall­ figure 13, both recovery and grade were ing sharply owing to increased gangue highest (97.5-pct recovery at a grade of flotation. 63 pct CaF2) with the preferred dosage. lOT ------rR~e~c=o:ve~r:y-----~ 100r------,,------,------.------. 90 70 90 Recovery

80 ~ 60 w ~ U 0:: 70 a::t5 ~ 50 w 0.. 60 40 50

30~--~--~----~--~----~--~ o 5 10 15 20 25 30 8.0 9.0 11.0 CONDITIONING TIME, min pH FIGURE 11..- Effect of oleic acid conditioning time FIGURE 12. - Effect of pH variation on fluorite on flotation of fluorite-mica sample. grade and recovery, fluorite-mica sample. 12

Mica Flotation 100~------r------'------, The only recoverable byproduct present in this sample was mica, which could be floated directly from the des limed fluorite tailings. The mica in this I-z 90 sample was different from the musco­ w vite found in the fluorite-beryllium a::(J sample; it contained considerable biotite W 60 and phlogopite along with muscovite. Q.. . Because the mica recovery stage was not an intermediate stage, no other analyti­ cal method could be used except petro­ graphic examination. The most effective method for treating this sample was 50L------~------~------~ an anionic-cationic flotation technique. 1.0 2.0 3.0 4.0 The fluorite tailings were deslimed by SODIUM SILICATE ADDITION, Ib/st decantation at approximately 20 ~m. De­ sliming was necessary in the mica flota­ FIGURE 13. - Effect of Na2Si03 addition on fluorite tion stage to reduce reagent consumption grade and recovery, fluorite-mica sample. caused by reagents adsorbing on the slime particles. The flotation conditions for mica recovery were (1) 15-min scrubbing Flotation Under Preferred Conditions of the deslimed fluorite tailings with 3 lb/st NaF, (2) 15-min CT with 0.5 lb/st Under preferred conditions--3 min CT Na zC03 , (3) 3-min CT with 0.5 lb/st lead with 2 lb/st Na2Si03, 10 min CT with nitrate [Pb(N03)Z], (4) pH adjustment to 1.5 lb/st oleic acid, and flotation pH of 9.2, (5) 10-min CT with 0.5 lb/st oleic 9.0--a fluorite rougher concentrate con­ acid, and (6) 2-min CT with 0.4 lb/st taining 77.3 pct CaF2 was produced with Arosurf MG83A (diether amine). Under a 92.5-pct fluorite recovery. This con­ these conditions approximately 85 pct centrate was cleaned four times without of the mica was recovered in a concen­ additional reagents other than those trate containing approximately 95 pct needed to maintain the pH level; the mica (table 7). fourth cleaner concentrate contained 96 pct CaFz with a recovery of 84 pct of the fluorite.

TABLE 7. - Fluorite and mica flotation from fluorite-mica sample, percent

Product Analysis Distribution CaF2 Mica l CaF2 Mica CaF z cleaner concentrate •• :t96.0 <1 84.0 0.5 Slimes •••...•••••.•..•..•• 6.3 5 7.3 2.5 Mica concentrate •••••••••• 1.8 95 6.6 85.0 Mica tailings ••••••••••••• 1.5 15 2.1 12.0 1Estimated by petrography. zSilica value was below product specification level for ceramic-grade fluorite. 13

CONCLUSIONS

Experimental results showed that fluo­ recQvery of 90 pct. A beryl concentrate rite readily floated from the fluorite­ was produced containing 75.3 pct of the beryllium sample using oleic acid beryl with a grade of 5.45 pct BeO. at pH 9.0. Bench-scale flotation using Experimental results showed that fluo­ 3 lb/st Na2C03' 3 lb/st Na2Si03' and rite can be floated from the fluorite­ 2 lb/st oleic acid recovered 94 pct of mica sample using oleic acid at pH 9.0. the fluorite in an acid-grade recleaner Flotation using 2 lb/st Na2Si03 and concentrate, which contained 98.1 pct 1.5 lb/st oleic acid produced a ceramic­ CaF2" A muscovite concentrate was ob­ grade recleaner concentrate containing tained from the deslimed fluorite tail­ 96 pct CaF2 at a recovery of 84 pct. ings using 3.0 lb/st H2S04 and 0.7 lb/st A mica concentrate containing 95 pct tallow amine acetate. The silicate min­ mica at 85 pct recovery was obtained erals were floated from the free silica from deslimed fluorite tailings using using 5 lb/st HF and 0.5 lb/st tallow 3 lb/st NaF, 0.5 lb/st Na2C03' 0.5 lb/st amine acetate. The silicate tailings Pb(N03)2' 0.5 lb/st oleic acid, and product contained 99 pct Si02 with a 0.4 lb/st diether amine. REFERENCES

1. Gossling, H. H., and H. W. A. 7. Bloom, P. A., W. A. McKinney, and McCulloch. Fluorspar-The Rise of a Non­ L. G. Evans. Flotation Concentration of metallic Mineral. Miner. Sci. Eng. (S. Complex Barite-Fluorite Ore. BuMines RI Africa), v. 6 No.4, Oct. 1974, p. 208. 6213, 1963, 16 pp. 2. Pelham, L. Fluorspar. Sec. in 8. Fluerstenau, M. C., D. A. Elgil­ BuMines Mineral Commodity Summaries, lani, and G. Gutierrez. The Influence of 1985, pp. 50-51. Sodium Silicate in Nonmetallic Flotation 3. Fluorspar. Ch. in BuMines System. Trans. Soc. Min. Eng. AlME, v. Minerals Yearbook 1983, v. 1, pp. 357- 241, 1968, p. 319. 366. 9. Hiskey, J. B. Electrokinetics of 4. Holmes Jr., G. H. Beryllium Inves­ CaF2" M.S. Thesis, Univ. UT, Salt Lake tigations in California and Nevada. City, UT, 1971, 64 pp. BuMines IC 8158, 1963, 19 pp. 10. Baarson, R. E., C. L. Ray, and 5. Horton, R. C. An Inventory of H. B. Treweek. Plant Practice in Non­ Fluorspar Occurrences in Nevada. NV Bur. metallic Mineral Flotation.Ch. in Froth Mines, McKay Sch. Mines, Univ. NV, Rep. Flotation-50th Anniversary Volume, ed. 1, 1961, 31 pp. by D. W. Fuerstenau. AIME, 1962, pp. 6. Clemmer, J. B., and B. H. Clemmons. 427-453. Concentrating Fluorspar by Froth Flo­ tation. U.S. Pat. 2,407,651, Sept. 17, 1946.

" u.s. GOVERNMENT PRINTING OFFICE: 1986-605·017/40,039 INT.-BU.OF MINES,PGH.,PA. 26283