DOCSLIB.ORG

UNITED States PATENT OFFICE 2,678,282 PROCESS for MANUFACTURING SYN THETIC NORGANIC SILICATES OR the LIKE Clifford Jones, Eccleston, St

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
UNITED States PATENT OFFICE 2,678,282 PROCESS for MANUFACTURING SYN THETIC NORGANIC SILICATES OR the LIKE Clifford Jones, Eccleston, St Patented May 11, 1954 2,678,282 UNITED STATEs PATENT OFFICE 2,678,282 PROCESS FOR MANUFACTURING SYN THETIC NORGANIC SILICATES OR THE LIKE Clifford Jones, Eccleston, St. Helens, England, as signor to Pilkington Brothers Limited, Lanca shire, England, a British company No Drawing. Application June 1, 1950, Seria No. 165,595 5 Claims. (CI. 06-65) 2 This invention relates to the manufacture of natural mullite and Sillimanite. They discounted a synthetic mullite. the suggestion of Bradley and Roussin that their Pure mullite is a very desirable refractory "Porzite' was a new aluminium silicate, and they material because it consists of closely interlock identified three forms of mullite, viz: ing crystals which give it good mechanical 5 1. or mullite.--This contains 72% of Al2O3 and strength, and because it contains no glassy ina 28% of SiO2 by weight: its formula is trix liable to drain out of the material in Serv ice as a result of its fusibility being lowered by external chemical attack. This form was not identified in any of the By the calcination at high temperature, usually O natural samples, but it was prepared syntheti above 1400° C., of Kaolin (Al2O3.2SiO2.2H2O), or cally by grinding together pure silica (SiO2) and of Kyanite or sillimanite (which are two dif pure alumina (Al2O3) in the correct proportions, ferent crystalline forms of Al2O3SiO2), or of and calcining the mixture at 1750. There is other aluminium silicates, it is relatively easy to no discloSure of the material being moulided into promote the growth of crystals of mullite, the 5 Shaped articles. formula of which is approximately 3Ai2O3.2SiO2: 2. 3 mullite-This contains 72% to 78% of but in the material So produced there is a residue Al2O3 and 28% to 22% of SiO2 by weight: its of excess silica (SiO2), usually in the form of a formula is approximately 3Al2O3.2SiO2. glassy matrix. This glassy matrix of Silica is The X-ray spectrum for this material was detrimental in refractories for tank-furnaces 20 found to correspond to that found for mullite used for the melting of glass from the raw in crystals in electrically fused (electro-cast) tank gredients because, in the conditions existing in furnace blocks, and to that for natural mullite such furnaces, it is liable to be attacked by al fi'On North America. A Substance very simi kaline dustS and furnace gaseS as a result of lar crystailographically was prepared artificially which its fusibility is lowered and it drains out 2 5 by mixing pure Silica (SiO2) with pure alumina, f the refractory material leaving an open por (Al2O3) in excess of the 72 to 28 alumina-to ous structure which may disintegrate in Service. Silica, ratio and calcining the mixture at i800. Thus, if a mullite refractory can be made in 3. y mullite.- This was found in Samples of which there is no glassy matrix that can cause natural material from the Isle of Mull (hence weakness by draining out of the structure in the 30 the name "mullite'). A material very similar to presence of alkaline dusts, etc., full advantage it was prepared by repeating the process de can be taken of the characteristically good me Scribed in ... above for the Synthesis of a mullite, chanical and chemical properties of pure mullite but replacing 1% of the alumina (Al2O3) by 1% as a refractory for high temperature service. of titania (TiO2) or by less than 1% of ferric Attempts to make an all-mullite refractory 35 oxide (Fe2O3). by introducing the correct quantity of alumina, Accordingly, the present invention provides a (Al2O3) to combine with this excess silica, usually process for the manufacture of Synthetic Inull result in a mixture of mullite, corundum (a ite wherein an intimate mixture of alumina, and particular crystalline form of Al2O3); and silica. aluminium silicate bonded by means of an ethyl For example, We have found that the calcina 40 Silicate is calcined at a temperature of at least tion of a mixture of crushed sillimanite (natural 1500° C., the proportions of the ingredients be rock) and alumina in the proportions present in ing such that the ratio of alumina to silica in mullite results in a material containing mullite the calcined mixture is between 72% and 78% and Corundum. by weight of Al2O3 and between 28% and 22% A. J. Bradley and A. L. Roussin (cf. Transac 45 by weight of SiO2. - tions of the Ceramic Society, (1932), 31, 422), The calcination temperature should be at have described mixtures of porcelains which on least 1500, but a higher temperature, e. g. of X-ray examination gave spectra similar to but i650 to 1700° C. may be attained when it is re not identical with that of mullite, and they Sug quired to produce a very dense material. gested that the material should be called “Por 50 The aluminium silicate (such as Kyanite or zite.' sillimanite) should be of high purity and both H. P. Rooksby and J. H. Partridge, (cf. Jour the aluminium silicate and the alumina must nal of the Society of Glass Technology, (1939), be finely ground (i. e. must pass through a 200 23, 338), have described results of the X-ray mesh Sieve or finer). examination of the structures of artificial and 55 Preferably, the binding agent is an ethyl silicate 2,678,282 3 4. or mixture of ethyl silicates, such as the material substitute for natural mullite Which comprises sold as silicon ester and usually containing 40 to calcining an intimate mixture of alumina, alu 47% by weight of silica (SiO2). The silicon ester minium silicate and ethyl silicate as a binding may conveniently be used in Solution in Water Or agent, at a tenperature of between 1500° C. and as a dispersion in an alcohol-water mixture, and 800° C., the initial proportions of the ingre the quantity of silicon ester thus introduced into dients being such that in the calcined mixture the the mixture can be adjusted according to the ratio of alumina to silica is between 72% and consistency required for consolidating the final 78% by Weight of Al2O3 and between 28% and Inix, as little as 1% by Weight of the dry mixture 22% by weight of SiO2. inay be appropriate in Some cases, and experi 0 2. A process for the manufacture of a synthetic nets have shown that a quantity of 5% by Substitute for natural mullite which comprises Weight of the dry mixture has produced very effi calcining an intimate mixture of alumina, alu cient results. iaiiium silicate and an ethyl silicate contain he ingredients should be very thoroughly ing between 40% and 47% by Weight of SiO2 as a mixed. When the Silicon ester breaks down, the 5 binding agent, at a temperature of between 1500 pure silica produced is in a very finely divided C. and 1800° C., the initial proportions of the State and is more reactive than ordinary fine ingredients being such that in the calcined mix ground silica. Since this silica is introduced as a ture the ratio of alumina, to Silica, is between 72% solution or dispersion it may be aSSunned to be and 78% by weight of Al2O3 and between 28% and very uniformly distributed. 20 22% by weight of SiO2. The following example illustrates how the 3. A process for the manufacture of a synthetic process of the invention may be carried into effect: Sui:stitute for natural nullite Which comprises 500 gms. of a natural rock sillimanite contain calcining an intimate mixture of alumina, alu ing 58% (=290 gms.) of Al2O3 and 39%. (=195 (niiniuin Silicate and an ethyl Silicate as a bind guns.) of SiO2 crushed to 200-mesh were inti 25 ing agent, at a temperature of between 1650 and imately mixed with 500 gms. of calcined alumina, 1700° C., the initial proportions of the ingredients Al2C3, crushed to 200-mesh and 247 c. c. of silicon icing Such that in the calcined mixture the ratio ester (containing 46.5% by weight of silica equiva of alumina, to silica is between 72% and 78% by lent to 112 gms, of SiO2) in an alcohol-Water So weight of Al2O3 and between 28% and 22% by lution consisting of 60 c. C. of alcohol and 27 c. c. Weight of SiO2. of water. Thus the ratio of total alumina, to total silica in the mixture was 72 to 28. The mixture, 4. A process for the manufacture of a Synthetic after shaping with a required article, was calcined Substitute for natural mullite which comprises at between 1650° C. and 1700° C. by heating in a intimately mixing together alumina, aluminium gas-air fired furnace. The product Was a Syn 35 silicate and an aqueous alcoholic Solution of an thetic annullite. ethyl silicate, calcining the mixture thus pro By slightly increasing the ratio of alumina to duced at a temperature of between 1500° C. silica, Bmullite may be prepared in a similar and 1800° C., the initial proportions of the in alle. gredients being such that in the calcined mix In the manufacture of refractories intended 40 ture the ratio of alumina to Silica is between 72% for use in the making of glass, experience has and 78% by weight of Al2O3 and between 28% and shown that the aluminium compound herein de 22% by weight al SiO2. scribed should be calcined at a temperature of 5. A process for the manufacture of a synthetic at least 1500° C. substitute for natural mullite Which comprises The mixture is eminently suitable for pressing, intimately mixing together alumina, Sillimanite haramering, jolting or slip-casting to the re and an aqueous alcoholic Solution of an ethyl quired shape before calcining.
Load more

Recommended publications
  • Sodium Aluminium Silicate (Tentative)
    SODIUM ALUMINIUM SILICATE (TENTATIVE) th Prepared at the 80 JECFA and published in FAO JECFA Monographs 17 (2015), superseding tentative specifications prepared at the 77th JECFA (2013) and published in FAO JECFA Monographs 14 (2013). An ADI 'not specified' for silicon dioxide and certain silicates was established at the 29th JECFA (1985). A PTWI of 2 mg/kg bw for total aluminium was established at the 74th JECFA (2011). The PTWI applies to all aluminium compounds in food, including food additives. Information required: Functional uses other than anticaking agent, if any, and information on the types of products in which it is used and the use levels in these products Data on solubility using the procedure documented in the “Compendium of Food Additives Specifications, Vol. 4, Analytical methods” Data on the impurities soluble in 0.5 M hydrochloric acid, from a minimum of five batches. If a different extraction and determination method is used, provide data along with details of method and QC data. Suitability of the analytical method for the determination of aluminium, silicon and sodium using the proposed “Method of assay” along with data, from a minimum of five batches, using the proposed method. If a different method is used, provide data along with details of the method and QC data. SYNONYMS Sodium silicoaluminate; sodium aluminosilicate; aluminium sodium silicate; silicic acid, aluminium sodium salt; INS No. 554 DEFINITION Sodium aluminium silicate is a series of amorphous hydrated sodium aluminium silicates with varying proportions of Na2O, Al2O3 and SiO2. It is manufactured by, precipitation process, reacting aluminium sulphate and sodium silicate.
    [Show full text]
  • SYNTHESIS of SOME ALUMINIUM SILICATES* by R. M. CARR~ And
    SYNTHESIS OF SOME ALUMINIUM SILICATES* By R. M. CARR~and J. B. DIXON~ Studies in the system A12034Si02 under hydrothermal conditions where three different starting materials (amorphous alumina-quartz, amorphous silica-kaolinite, quartz-kaolinite) were investigated in "pinched-tube" experiments1 were followed by a redetermination in sealed-tube experiments of the synthesis fields obtained from amorphous silica-kaolinite and quartz-kaolinite.2 A synthesis diagram for the starting material amorphous alumina-quartz has now been redetermined in sealed-tube experiments. Experimental The pressure equipment used is similar to that already described.2 Modifications to the equipment, in the form of stellite test-tube bombs each coupled to a Bourdon pressure gauge and controlled with an Ether transitrol temperature regulator, enabled more effective control to be attained in some of the experiments. Errors in temperature control were within &l% at all temperatures. Quartz and amorphous (chromatographic) alumina were mixed in the molecular proportions A1203,4SiOz and Aln03,6SiOz. Samples together with water were placed in silver capsules and sealed. Runs commenced with rapid heating periods (e.g. from room temperature to 400' in 20 min) and were terminated with air quenching. Products were examined with a Philips X-ray diffractometer using filtered Cu radiation. Results A comparison of synthesis field boundary temperatures for pinched-tube and sealed-tube experiments with the starting material amorphous alumina-quartz is given in Table 1. Minor amounts of boehmite were present in many low-temperature runs, indicating sluggish reaction between this phase and quartz. Two decomposition experiments provided confirmation of the synthesis boundaries. Synthetic corundum heated at 490' under a hydrostatic pressure of 30000 lb/inZ was partly altered to pyrophyllite, and kaolinite was obtained from synthetic pyrophyllite at 370".
    [Show full text]
  • Application of Mineral and Allumino Silicates in Te Electronic and Telephone Industries in India
    ACTA SCIENTIFIC AGRICULTURE (ISSN: 2581-365X) Volume 2 Issue 11 November 2018 Conceptual Paper Application of Mineral and Allumino Silicates in Te Electronic and Telephone Industries in India Arun K Shandilya* Department of Applied Geology, DR. H. S. G. University, India *Corresponding Author: Arun K Shandilya, Department of Applied Geology, DR. H. S. G. University, India. Received: September 20, 2018; Published: October 30, 2018 The studies on the varieties of glasses have been carried out to The composition of the glass is determined by the geochemi- under stand the strength of various type of the glasses are avail- cal analyses. The general composition of the glasses- frequently able in our country. expressed as the basis of SiO2 content, can be estimated from the glass index of refraction. The naturally occurring glass do not have a high hardness and good quality, generally it breaks, when the variety of compression - rence on mineral and rocks are known. force/tensile force, or couple shear forces are active on these glass- Dispersion or specific gravity, particularly if its mode of occur es. The verities of glasses are available as per the utility of glasses, The chemical composition of some important silicate minerals the manufacturer have as per their own requirement with differ- are as follows: ent composition. 1. Anorthite- Ca AlSi3O8 The varieties of glasses can be manufactured with a variety of 2. Andesine - Ca AlSi3O8 combination in the mineralogical composition, give good the qual- 3. Labradorite- Ca NaAlSi3O8 ity glass. There are two type of the glasses are- (1) Natural glass 4. Bytownite - Ca NaAlSi3O8 5.
    [Show full text]
  • Safety Evaluation of Certain Food Additives and Contaminants
    WHO FOOD Safety evaluation of ADDITIVES SERIES: 58 certain food additives and contaminants Prepared by the Sixty-seventh meeting of the Joint FAO/WHO Expert Committee on Food Additives (JECFA) ALUMINIUM (addendum) (pages 119-207) World Health Organization, Geneva, 2007 IPCS — International Programme on Chemical Safety ALUMINIUM FROM ALL SOURCES, INCLUDING FOOD ADDITIVES (addendum) First draft prepared by D.J. Benford,1 N. Thatcher,1 D. Mason,1 D. Street,2 C. Leclercq,3 M. DiNovi,2 J. Bend4 & B. Whitehouse5 1 Food Standards Agency, London, England; 2 Center for Food Safety and Applied Nutrition, United States Food and Drug Administration, College Park, MD, USA; 3 Food Safety Exposure Analysis, Istituto Nazionale di Ricerca per gli Alimenti e la Nutrizione (INRAN), Rome, Italy; 4 Department of Pathology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada; and 5Bowdon, Cheshire, England Explanation ................................................................................ 120 Introduction ......................................................................... 120 General considerations on exposure ............................ 121 Biological data ........................................................................... 121 Biochemical aspects ........................................................... 121 Absorption, distribution and excretion ........................... 121 Effects on enzymes and other parameters ................... 130 Toxicological studies ..........................................................
    [Show full text]
  • Kyanite - Properties and Indian Occurrences
    KYANITE - PROPERTIES AND INDIAN OCCURRENCES Kyanite which is an aluminium silicate with chemical formula Al2SiO5, belong to the Sillimanite group of minerals high alumina refractories. Especially, raw Kyanite is extensively used for making high alumina insulation Refractory Bricks. comprising Sillimanite, Kyanite, Andalusite, Dumortierite and Topaz. Kyanite is an important raw material for Apart from refractory industry kyanite particularly its blue variety, is also used as gem stone. The kyanite gem stone is believed to possess certain metaphysical properties with its ability to keep the mind calm and anxiety under control. The name Kyanite was derived from the Greek word Kyanos which means blue. Mineralogy of Kyanite Kyanite is found as subhedral and tabular to elongated, thin, bladed crystals having blue or light-green colour in the form of crystalline aggregates in schists, gneisses, granite pegmatite and occasionally in eclogites. The crystal system is Triclinic; optically kyanite is colourless and feebly pleochroic from pale- blue to colourless with one set of perfect cleavage, first and second order interference colour (yellow, grey and blue). The distinguishing features of kyanite are its higher refractive index than those of Sillimanite and Andalusite while birefringence is lower. The oblique extinction angle up to 32O together with the biaxial interference, negative optic sign, and large optic axial angle are also distinctive for kyanite. Its hardness varies from 4 to 7 (Moh’s scale) and specific gravity is around 3.6-3.7. Indian Occurrences In the Indian subcontinent very good gem quality kyanite is found Nepal. Kyanite is formed at medium temperatures and high pressures in a regionally metamorphosed sequence of rocks and is found associated with minerals like - muscovite, quartz, garnet, staurolite and rutile.
    [Show full text]
  • Safety Evaluation of Certain Food Additives and Contaminants / Prepared by the Seventy-Fourth Meeting of the Joint FAO/WHO Expert Committee on Food Additives (JECFA)
    WHO FOOD Safety evaluation of ADDITIVES certain food additives SERIES: 65 and contaminants Prepared by the Seventy-fourth meeting of the Joint FAO/ WHO Expert Committee on Food Additives (JECFA) World Health Organization, Geneva, 2012 WHO Library Cataloguing-in-Publication Data Safety evaluation of certain food additives and contaminants / prepared by the Seventy-fourth meeting of the Joint FAO/WHO Expert Committee on Food Additives (JECFA). (WHO food additives series ; 65) 1.Food additives - toxicity. 2.Food contamination. 3.Flavoring agents - analysis. 4.Flavoring agents - toxicity. 5.Risk assessment. I.Joint FAO/WHO Expert Committee on Food Additives. Meeting (74th : 2011 : Rome, Italy). II.World Health Organization. III.Series. ISBN 978 92 4 166065 5 (NLM classification: WA 712) ISSN 0300-0923 © World Health Organization 2012 All rights reserved. Publications of the World Health Organization are available on the WHO web site (www.who.int) or can be purchased from WHO Press, World Health Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland (tel.: +41 22 791 3264; fax: +41 22 791 4857; e-mail: [email protected]). Requests for permission to reproduce or translate WHO publications—whether for sale or for non-commercial distribution—should be addressed to WHO Press through the WHO web site (www.who.int/about/licensing/copyright_form/en/index.html). The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the World Health Organization concern ing the legal status of any country, territory, city or area or of its authorities, or concern ing the delimitation of its frontiers or boundaries.
    [Show full text]
  • Human Health Risk Assessment for Aluminium, Aluminium Oxide, and Aluminium Hydroxide
    University of Kentucky UKnowledge Pharmaceutical Sciences Faculty Publications Pharmaceutical Sciences 2007 Human Health Risk Assessment for Aluminium, Aluminium Oxide, and Aluminium Hydroxide Daniel Krewski University of Ottawa, Canada Robert A. Yokel University of Kentucky, [email protected] Evert Nieboer McMaster University, Canada David Borchelt University of Florida See next page for additional authors Right click to open a feedback form in a new tab to let us know how this document benefits ou.y Follow this and additional works at: https://uknowledge.uky.edu/ps_facpub Part of the Pharmacy and Pharmaceutical Sciences Commons Authors Daniel Krewski, Robert A. Yokel, Evert Nieboer, David Borchelt, Joshua Cohen, Jean Harry, Sam Kacew, Joan Lindsay, Amal M. Mahfouz, and Virginie Rondeau Human Health Risk Assessment for Aluminium, Aluminium Oxide, and Aluminium Hydroxide Notes/Citation Information Published in the Journal of Toxicology and Environmental Health, Part B: Critical Reviews, v. 10, supplement 1, p. 1-269. This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of Toxicology and Environmental Health, Part B: Critical Reviews on April 7, 2011, available online: http://www.tandfonline.com/10.1080/10937400701597766. Copyright © Taylor & Francis Group, LLC The copyright holders have granted the permission for posting the article here. Digital Object Identifier (DOI) http://dx.doi.org/10.1080/10937400701597766 This article is available at UKnowledge: https://uknowledge.uky.edu/ps_facpub/57 This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of Toxicology and Environmental Health, Part B: Critical Reviews on April 7, 2011, available online: http://www.tandfonline.com/10.1080/10937 400701597766.
    [Show full text]
  • Sodium Aluminium Silicate
    0 out of 3 Residue Monograph prepared by the meeting of the Joint FAO/WHO Expert Committee on Food Additives (JECFA), 84th meeting 2017 Sodium Aluminium Silicate This monograph was also published in: Compendium of Food Additive Specifications. Joint FAO/WHO Expert Committee on Food Additives (JECFA), 84th meeting 2017. FAO JECFA Monographs 20 © FAO/WHO 2017 1 out of 3 SODIUM ALUMINIUM SILICATE Prepared at the 84th JECFA and published in FAO JECFA Monograph 20 (2017), superseding tentative specifications prepared at the 80th JECFA (2015) and published in FAO JECFA Monographs 17 (2015). An ADI 'not specified' for silicon dioxide and certain silicates was established at the 29th JECFA (1985). A PTWI of 2 mg/kg bw for total aluminium was established at the 74th JECFA (2011). The PTWI applies to all aluminium compounds in food, including food additives. SYNONYMS Sodium silicoaluminate; sodium aluminosilicate; aluminium sodium silicate; silicic acid, aluminium sodium salt; INS No. 554 DEFINITION Sodium aluminium silicate is a series of amorphous hydrated sodium aluminium silicates with varying proportions of Na2O, Al2O3 and SiO2. It is manufactured by reacting aluminium sulphate and sodium silicate followed by precipitation. Chemical names Aluminium sodium silicate C.A.S. number 1344-00-9 Chemical formula xSiO2 · yAl2O3 · zNa2O Assay Silicon dioxide (SiO2): Not less than 66% and not more than 88%. Aluminium oxide (Al2O3): Not less than 5% and not more than 15%. Sodium oxide (Na2O): Not less than 5% and not more than 8.5%. All values expressed on the dried basis. DESCRIPTION Odourless, fine, white amorphous powder, or as beads FUNCTIONAL USES Anticaking agent CHARACTERISTICS IDENTIFICATION © FAO/WHO 2017 2 out of 3 Solubility (Vol.
    [Show full text]
  • Kyanite, Sillimanite & Andalusite
    KYANITE, SILLIMANITE AND ANDALUSITE Indian Minerals Yearbook 2013 (Part- III : MINERAL REVIEWS) 52nd Edition KYANITE, SILLIMANITE AND ANDALUSITE (FINAL RELEASE) GOVERNMENT OF INDIA MINISTRY OF MINES INDIAN BUREAU OF MINES Indira Bhavan, Civil Lines, NAGPUR – 440 001 PHONE/FAX NO. (0712) 2565471 PBX : (0712) 2562649, 2560544, 2560648 E-MAIL : [email protected] Website: www.ibm.gov.in July, 2015 30-1 KYANITE, SILLIMANITE AND ANDALUSITE 30 Kyanite, Sillimanite and Andalusite yanite, sillimanite and andalusite are three others and not-known grades 1.6%. Statewise, Kaluminium silicate minerals having the same share of Andhra Pradesh alone is more than 78% of total resources followed by Karnataka 13% and chemical composition (Al2O3.SiO2) but differing in physical properties. These minerals are also Jharkhand 6%. Remaining 3% resources are in known as 'super-refractories' in view of their Kerala, Maharashtra, Rajasthan, Tamil Nadu and special refractory properties. These minerals West Bengal (Table - 1). have special property of undergoing conversion into mullite (3Al2O3.2SiO2) and vitreous silica Sillimanite (cristobalite) on heating between 1,3500C and The total resources of sillimanite as per UNFC 1,5000 C. The conversion takes place with about system in the country as on 1.4.2010 are placed 20% increase in volume and hence it is necessary at 66.98 million tonnes. Out of these resources, to calcine these minerals before use. Mullite the reserves are only 4.08 million tonnes, while (artificial) is the most important constituent of about 62.90 million tonnes are the remaining refractory products as it shows little or no resources. Out of total resources, more than 72.1% softening below its melting point (1,8100C).
    [Show full text]
  • Evaluation of Certain Food Additives and Contaminants
    WHO Technical Report Series 995 Evaluation of certain food additives and contaminants Eightieth report of the Joint FAO/WHO Expert Committee on Food Additives The World Health Organization was established in 1948 as a specialized agency of the United Nations serving as the directing and coordinating authority for international health matters and public health. One of WHO’s constitutional functions is to provide objective and reliable information and advice in the field of human health, a responsibility that it fulfils in part through its extensive programme of publications. The Organization seeks through its publications to support national health strategies and address the most pressing public health concerns of populations around the world. To respond to the needs of Member States at all levels of development, WHO publishes practical manuals, handbooks and training material for specific categories of health workers; internationally applicable guidelines and standards; reviews and analyses of health policies, programmes and research; and state-of-the- art consensus reports that offer technical advice and recommendations for decision-makers. These books are closely tied to the Organization’s priority activities, encompassing disease prevention and control, the development of equitable health systems based on primary health care, and health promotion for individuals and communities. Progress towards better health for all also demands the global dissemination and exchange of information that draws on the knowledge and experience of all WHO’s Member countries and the collaboration of world leaders in public health and the biomedical sciences. To ensure the widest possible availability of authoritative information and guidance on health matters, WHO secures the broad international distribution of its publications and encourages their translation and adaptation.
    [Show full text]
  • Utilisation of Sillimanite Minerals, Their Geology, and Potential Occurrences in Norway – an Overview
    NGU-BULL 436, 2000 - PAGE 113 Utilisation of sillimanite minerals, their geology, and potential occurrences in Norway – an overview PETER M. IHLEN Ihlen, P.M. 2000: Utilisation of sillimanite minerals, their geology, and potential occurrences in Norway – an overview. Norges geologiske undersøkelse Bulletin 436, 113-128. The aluminium-silicate polymorphs sillimanite, andalusite and kyanite decompose to a mixture of mullite and silica glass during calcination. Mullite is an essential component of high-alumina refractories forming the inner lining of furnaces and high-temperature vessels widely used in the production of metals, ceramics, glass and cement. Sillimanite, andalusite and kyanite constituted 2%, 74% and 24%, respectively, of the total western world’s production of sillimanite minerals in 1998 of a total of about 401 000 tonnes, of which about 95% was consumed by the refractory industry. The sillimanite minerals are mined mainly in South Africa (62%; andalusite), USA (23%; kyanite) and France (11%; andalusite), whereas the major consumers are found in the major iron- and steel- producing areas of the world. Production has declined over the last decade, due mainly to cutbacks in iron and steel production. Most economic deposits of sillimanite minerals can be classified as metamorphogenic and include contact-metamorphic andalusite deposits, stratabound podiform deposits of massive (corundum)-sillimanite and (corundum)-kyanite rocks and stratiform deposits of kyanite quartzites. The former occur within metapelitic sequences in the contact aureoles of plutonic massifs, whereas the two latter in most cases are interpreted as representing metamorphosed high-alumina sediments, derived from hydrothermal alteration centres in subaerial felsic to intermediate volcanites. All of these deposit types have also been recognised in Norway.
    [Show full text]
  • A TABULATION of the ALUMINIUM SILICATE MINERALS. Eocen T
    I4.O THE AMERICAN MINERALOGIST' A TABULATION OF THE ALUMINIUM SILICATE MINERALS. Eocen T. Wnnnny, Bureau of Chemistry,Washington, D. C. The usual form of triangular diagram employed in plotting mineral analyses has certain inconvenient features, such as the difficulty of purchasingprinted triangular codrdinate paper with suitable spacings, the necessity of recalculating the analytical data or of laying ofi lines representing partial amounts across the corners of the triangle, etc. A modification which the writer has found usefulin the study of minerals with three essentialcom- ponents is here described. On two axes of ordinary rectangular codrdinate paper lay off percentagesfrom zero to 100, and draw a diagonal line connecting the two 100points.From the common zeropoint draw a perpendic- ular to the diagonal line, and on this medial axis lay off percent- agesstarting with the zero of the others as 100, and ending with zero at the intersectionwith the diagonal line. Then, when two of the componentsof the mineral seriesto be plotted are laid ofi with referenceto the rectangular axes, the third component becomes enteredautomatically on the medial one. fn the case of the aluminium silicate minerals, the diagram is prising water and alkalies, taking up its place on the medial axis. Variation in silica-alumina ratio then leads to shifting the position of a given mineral up and down; while variation in water content moves it right and left along lines diverging at small angles from the medial axis. fn order to decide which ratios are probably fundamental, & harmonic seriesof numbers, such as have been used with marked successin crystallography and other fields of scienceby professor Victor Goldschmidt, was applied; there being about sevenimpor_ tant ratios concerned,the series.N3 was the one selected.
    [Show full text]