Document zQBdrywz7R06wB7LRNpLNnDJ6

Bureau of Mines Preprint from Bulletin 675 ASBESTOS A Chapter from Mineral Facts and Problems, 1985 Edition UNITED STATES DEPARTMENT OF THE INTERIOR CTD007099 *1 UNITED STATES DEPARTMENT OF THE INTERIOR Donald Paul Hodel, Secretary BUREAU OF MINES Robert C. Horton, Director As the Nation's principal conservation agency, the Department of the Interior has responsibility for most of our nationally owned public lands and natural resources. This includes fostering the wisest use of our land and water resources, protecting our fish and wildlife, preserving the environmental and cultural values ofour national parks and historical places, and providing for the enjoyment of life through outdoor recreation. The Department assesses our energy and mineral resources and works to assure that their development is in the best interests of all our people. The Department also has a major responsibility for American In dian reservation communities and for people who live in island terrritories under U.S. administration. This publication is preprinted from Bulletin 675. MINERAL FACTS AND PROBl.F.MS. 1985 edition Hie complete volume, when published, may be purchased from the Superintendent of Documents. Washington, D.C. 20402 CTD007W0 V1 ASBESTOS By Robert A. Clifton' The United States is probably still second only to the U.S.S.R. in the consumption of asbestos, although data to confirm it are lacking. The construction industry worldwide now uses the major ity of asbestos fibers in such products as asbestos cement pipe and sheet, roofing products, flooring products, paints, and caulk ing, and should remain the largest user. U.S. mines produced 70,000 tons,' 33% of domestic consumption, which was 217,000 tons in 1983. Canada supplies about 94% of asbestos imports into the United States. The Republic of South Africa is second. The Republic of South Africa supplies all the U.S. demand for crocidolite and amosite, and the majority of imports from that country are these fibers. World asbestos production declined by 14% from 1979 to 1982. The market losses were almost totally in mature market economy countries and were keyed to the recession and environmental prob lems. The market growth in the developing countries eased the decline somewhat. The U.S.S.R. is the world's largest producer of asbestos. The level of activity in exploration, evaluation, and development of new ore bodies in Canada signals that it will probably continue as the leading world exporter. U.S. demand in 1983 was just 33% of the 1976 record high. It showed, in 1984, the first increase since 1978. The quest for substitutes remains strong, but the substitute materials proposed generally fail to compete with asbestos when measured by qual ity and/or economic yardsticks. Viable substitutes are desirable for both health and economic reasons. The health hazards associated with asbestos are still undergoing close scrutiny by Federal and local governments, unions, industry organizations, and environmentalists. The many areas of con troversy give promise of prolonged dispute. Efforts to regulate conditions to minimize the hazard are given as a reason for the closure of two asbestos mines in the United States. INDUSTRY STRUCTURE Background Canada, with major activity in the Province of Quebec, leads the market economy countries in both total quantity produced and the size of individual mines and mills. The U.S.S.R. is the leading world asbestos producer. The Republic of South Africa, Zimbabwe, China, Brazil, Italy, and the United States mine substantial tonnages and, in combination with Canada and the U S S R., produce over 94% of the world's supply. Chrysotile is the variety most in demand by over 95% of the world's con sumers, and most of the data in this report relate to chrysotile. Total world production in 1983 was 4.2 million tons ofall grades and varieties. Canada's share was 20%; the U.S.S.R. produced 54%; the Republic of South Africa and Zimbabwe, 5% each; China, Brazil, and Italy, 3% each; and Greece and the United States, 2% each. U.S. production was 70,000 tons, valued at 128 million. These data on world production do not credit U.S.S.R. production with the lower grades that are not used as fibers. 'PhyticaJ Kieimit, Section of NometaUic Mineral* 'AD tonnage* reported are metric loni unleu otherwise specified Tabls 1.--World asbestos production, 1983, and capacity, 1983, 1984, and 1990 (Thousand motric ions) Chfyeoote: North America Canada .............................. Manico................ Unbad State.................... Tata.............................. Production Capacity 1983 1983* 1964* 1990' 829 1,510 1,500 1,500 -- -- -- SO 70 100 100 50 899 1,610 1.800 1.600 South America: Brazil................................ Colombia............................ Total 136 200 200 200 7 7 10 25 142 207 210 225 Europe: Qreece.............................. Italy.............................. USSR........................ YuQoelavta .................. Other................................ Total ............................ 93 120 2S0 10 1 2.474 100 190 Z600 20 7 2.077 100 150 2,800 20 7 2,877 100 190 3,000 50 7 3.347 Africa: South Africa, AapubHc of Smzland.......................... Zimbabwe ............ Othar.................................. To............................ Aeta. China............................ Cyptua.............................. India.................................. Japan .............................. Korea. RapuNc of . Taiwan .................... Turtcay................................ Total .................... Oceania' Auatraiia........................ mwo--no-i en- rya--o-ta-n -to-tal ... 93 120 120 ISO 31 50 50 0 190 260 260 250 1 11 1 315 421 421 401 110 300 300 400 18 35 35 36 26 32 36 40 4 44 4 15 IS IS 20 3 44 5 4 15 15 26 179 386 408 S28 20 4,029 70 5,570 70 5.586 100 6,202 CroctdoMta: South Africa napubhc of Amoaita: South Africa Rapublic of Eerimeted. 'Forecast. 87 210 210 230 41 110 100 130 Geographic Distribution Only three mines in the United States continue to produce asbestos. Each of the three, two in California and another in Ver mont, produce chrysotile. An area roughly 120 kilometers' long and 8 to 10 kilometers wide, beginning 130 kilometers east of Montreal, Canada, and continuing eastward, contains the world's second largest mine and mill and, in toto, the largest concentration of known deposits in the world. Mergers and closings have reduced the number of operating companies to five in this ` ` Eastern Townships' ' region, stretching from Danville to East Broughton, Quebec. *One mile - 1 6093 kilometer*. I kilometer - 0 6213 mile CTD007101 2 MINERAL FACTS AND PROBLEMS MAJOR INTERNATIONAL ASBESTOS MINING GROUPS1 U.S.A. CANADA UNITED KNMOOM ZIMBABWE 9 Figure 1--Major asbestos mining groups. CTD007102 ASBESTOS 3 U S and British interests in the area have declined sharply. The Province of Quebec's Societe Nationale de I'Amiante (SNA) takeover of the Asbestos Corp. in 1981 and purchase of Bell Asbestos Ltd. in 1980 led the way. Then, in 1983, the Manville Corp. sold its Jeffrey Mine and mill to a Canadian consortium. The Jim Walter Corp.'s Carey Canadian Mines Ltd. and the ASARCO Corporation's Lac d'Amiante du Quebec Ltd. are the only U.S.-owned asbestos mines operating in Quebec. Cassiar Asbestos Corp. Ltd. in British Columbia is now totally owned by British and Canadian interests. The large integrated international corporation is no longer typical of the asbestos industry, as the Manville Corp. sold both its asbestos producing and manufacturing units and Cape Asbestos Ltd. sold its mines. Turner and Newell Ltd. now produces asbestos only in Zimbabwe and Swaziland and, along with the Etemite Group, are the only multinational corporations in the industry that both mine asbestos and manufacture asbestos products. Definitions and Grades The American Society for Testing and Materials (ASTM) has a new publication, much of which is devoted to asbestos defini tions (5).' The compromise definition, which should be useful to both the environmental and minerals communities, is given below as well as excerpts from mineralogical definitions found in that paper. Asbestos is a term applied to six naturally occurring minerals exploited commercially for their desirable physical properties, which are in part derived from their asbestiform habit. The six minerals are the serpentine mineral chrysotile and the amphibole minerals grunerite asbestos (also referred to as amosite), riebeckite asbestos (also referred to as crocidolite), anthophyllite asbestos, tremolite asbestos, and actinolite asbestos. (These minerals are defined in the sections that follow.) Individual mineral particles, however processed and regardless of their mineral name, are net demonstrated to be asbestos if the length-to-width ratio is less than 20:1. Serpentine Asbestos Chrysotile, the only commercial asbestos mineral belonging to the serpentine group, has an ideal chemical composition of MgjSijOs(OH). Moderate amounts of aluminum may substitute 'lialtcixed numben in (brenthew* refer to item* in the list of references u the end of this chapter for silicon and moderate amounts of iron may substitute for magnesium. Certain end-use applications are sensitive to the iron content. Small amounts of manganous oxide (MnO), calcium oxide (CaO), potassium oxide (KjO), and sodium oxide (NajO) are also reported in the chemical analyses. The crystal structure of chrysotile asbestos consists of double layers, each consisting of a layer of linked SiO tetrahedra coor dinated to a second layer of linked MgO?(OH) octahedra through a sharing of oxygen atoms; the composite double layer rolls up, like a window shade, to form long hollow tubes. The diameters of the individual tubes are on the order of 25 nanometers, and the length-to-diameter ratio can vary from 20:1 to well over 10,000:1. Chrysotile is characterized by a combination of (1) a distinc tive shape, (2) a chemical composition close to MgjSijOj(OH)., and (3) characteristic X-ray and electron diffraction patterns. Amphibole Asbestos Five of the six commercial asbestos minerals belong to the am phibole mineral group. These, with their ideal chemical formulas, are grunerite asbestos, Fe>SiOjj(OH)i (usually but improperly referred to by the name amosite); riebeckite asbestos, NaFejl*Fe,*SitOji(OH)5 (usually referred to by the varietal name crocidolite); anthophyllite asbestos, Mg?SiOjj(OH);; tremolite asbestos, CajMgjSiiOj^OH)}; and actinolite asbestos, Ca^Mg.Fe^sSiiOi^OH)?. A considerable amount of substitu tion of other elements for Fe*\ Fe5*, silicon, sodium, calcium, and magnesium can take place in these minerals. The crystal structure of the amphibole minerals, including the asbestiform varieties, are composed of strips or ribbons of linked polyhedra, which join together to form the three-dimensional crystal. The individual strips are composed of three elements: these are two double chains of linked (Si,Al)04 tetrahedra and a strip of linked MgOt, FeOe, or AlOs octahedra. The threedimensional arrangements of these strips ("I-beams") are orthoamphibole (anthophyllite asbestos) and clinoamphiboie (tremolite, actinolite, grunerite, and riebeckite asbestos). Amphibole asbestos minerals are characterized by a combina tion of (1) a distinctive crystal habit with length-to-width ratios often of 20:1 or greater, (2) the typical chemical composition for that mineral, and (3) characteristic X-ray powder diffraction patterns or electron diffraction patterns. Tremolite asbestos was included in spite of no longer being an item of commerce because of the continuing controversy over the health effects of tremolite in talc. Component SiO Alrfl, PiO, FeO MnO . MgO CaO K.0 NtiO H&+ .... HiOCO, Total.. Table 2.--Chamleal eompoaftfon of aabaatoa, weight percent Serpentine asbestos, chrysotile King Beaver Mine. Quebec. Canada Shabani Mines. Zimbabwe 38.75 3.09 1.59 2.03 06 39.78 .69 16 10 12.22 .60 48 99.79 39.70 317 .27 .70 .26 40.30 1.06 .05 .04 12.17 .64 2 13 100.51 Riebeckite asbestos (crocidolite), from Pomtret. Caps Province. Republic of South Africa 52.00 Nil 16.05 1765 Trace 4.28 1.20 .06 6.21 2 43 .26.09 100.23 Amphibole asbestos Grunerite asbestos (amosite), from Penge. Transvael Pro vince, Republic ol South Africa Anthophyl lite asbestos, from Paakkila. Finland 49.70 .40 .03 39.70 .22 6.44 1.04 .63 .09 1.63 .09 .09 100.26 57.20 Nit .13 10 12 Nil 29.21 1.02 Nil NH 2.18 28 100.14 Tremolite asbestos. from Pakistan 55.10 1.14 32 2.00 10 2S.65 11.45 .29 14 352 .16 .06 99.93 CTD007103 4 MINERAL FACTS AND PROBLEMS Chrysotile, the principal variety of commerce, is graded and grouped according to fiber length. Most of the groups are divided into several subgroups to comprise the commercial specifications. One producer alone has offered its customers 420 grades of fiber in 1,320 different forms (5). The methods of classification used in the principal producing countries are discussed in detail in a Bureau of Mines publication (2). RESERVES-RESOURCES U.S. and World The definitions of reserves and reserve base are published in the U.S. Geological Survey Circular 831,"Principles of a Resource/Reserve Classification for Minerals," which is reprinted in the introduction of "Mineral Facts and Problems, 1985 Edition." Recent economic pressures of remaining competitive while meeting environmental regulations are increasing production costs and thereby causing reserve estimates to decrease. The possible million tons of asbestos fiber reserves at the Copperopolis, CA, deposit are, under present environmental regulations, economic. The future of the millions of tons of short fibers available in the Coalinga, CA, area is doubtful, because of low demand and high environmental costs. The world reserve situation and its implications for the future remain unclear. The plans of the U.S.S.R. to bring more asbestos mines into production indicate huge resources, but it is ques tionable whether they are all reserves using market economy yard sticks. Also questionable is whether the economy and demand for asbestos would raise prices to the level that certain large Cana dian and Alaskan resources would become economically attrac tive. Present trends in world demand indicate that those resources presendy called "reserves" will be adequate to meet that demand through the year 2000. Geology Most chrysotile asbestos deposits, including those of Vermont, Alaska, and California in the United States as well as of Canada, Zimbabwe, Swaziland, the Republic of South Africa, and the U S S R., consist of irregular cross-fiber veins (closely packed fibers set at a right angle to the faces of the rock fractures) or slip-fiber zones (shear planes in rock, filled with fiber matted together parallel to the seam) in massive serpentine. Such deposits commonly extend to unexplored depths. Amosite and crocidolitc of the Republic of South Africa occur in banded ironstones that are so folded and contorted that the veins are very irregular. Table 3.--World asbestos reserves and reserve base (Million metric tons) Nonh Amenca. United States Other Total Reserves Reserve base 48 40 47 44 55 South Amenca Europe Afnca . Asia Oceania . 4 50 7 6 1 World total' no 'Does not add to totals shown because of independent rounding. 5 65 10 13 1 150 TECHNOLOGY Exploration and Development Exploration and development are apparently decreasing throughout the world because of the decreasing demand for asbestos fiber and plenty of production capacity to meet that demand. The asbestos showings in the Eagle Quadrant of Alaska have been extensively explored and tested, but no decision on production has yet been made. Canadian development has practi cally ceased, and only the U.S.S.R. has active development plans. Mining In Vermont and in the Copperopolis district in California, the fiber-bearing rock is removed from an open pit. In the Coalinga district of California, the highly sheared ore is simply "plowed" and allowed to air-dry, and the coarse fraction is then screened out from the mill feed. The Canadian mines generally are open pits. The chrysotile of Zimbabwe, the Republic of South Africa, and Swaziland is obtained from underground mines. Amosite is obtained chiefly from large underground workings, and blue asbestos (crocidolitc) is taken from small open pits and shallow mines. The Soviet deposits are worked both in open pits and underground. Cyprus has large open pit workings. Processing Asbestos dry milling is a complex operation involving primarily the separation of fiber from rock and classification of fiber by length. There has been litde change in the basic methods described in a previous Bureau of Mines publication (3). Special milling techniques have been developed for the matted short-fiber chrysotile of the Coalinga district of California, in cluding grinding and wet-milling. In Copperopolis, CA, Vermont, and Canada, the mills are large and complex. The fiber is classified in many grades, such as spinning, cement stock, and paper stock. In many mills, asbestos fiber is packed under pressure in fiveply paper and/or woven vinyl bags. Each pressure-packed bag contains 100 pounds of asbestos and occupies about 2 cubic feet. With this pressure-packing, the asbestos measures 45 cubic feet per short ton. British patent application WD 83/04190A, in 1983, describes a two-stage Australian wet process. In the first stage, crushed chrysotile ore slurried with water is comminuted by crushing or grinding to release asbestos fibers and open the fiber bundles; the fibers are then concentrated by screw classifier and spiral con centrator. In the second stage, the concentrated fibers are cleaned by low-pressure hydrocydones and then separated into wellopened and poorly opened fibers by high-pressure hydrocycloning. Poorly opened fibers are mechanically milled and recycled. The well-opened concentrates are dewatered by high-pressure filtra tion. The patent application claims that the process concentrate yields are at least equal to those obtained by the conventional dry process. It is also claimed that the process is suitable for reclaiming fibers from dry process tailings and capable of treating the low-grade ores that the dry process cannot handle. Products for Trade and Industry The environmental problems of asbestos continue to depress its entry into new markets. New product inventors and designers as well as old product redesigners apparently no longer think of asbestos as a desirable, available, and economic raw material. CTD007104 ASBESTOS 5 Current Research and Applications The vast majority of current research concerning asbestos is divided into two totally separate areas: health and substitutes. They are linked because the perceived bad health effects feed the drive for safer substitutes. Each are discussed later in this chapter. USES Asbestos is used only after processing to release the fibers from the rock matrix and from each other. The processed chrysotile fibers are grouped by fiber length as follows: Groups 1,2, and 3.--These groups are composed of the longest fibers; the major end-use products include fireproof textiles, clothing, and theater curtains; also different types of packings, woven brake linings, clutch facings, electrical insulation materials, and high-pressure and marine insulation. Group 4.--Its major use is in asbestos cement pipe, which is used mainly in transporting water, such as in municipal water works, irrigation, and conservation projects. Group 5.--This group is used in asbestos cement sheets, lowpressure asbestos cement pipes, and molded products. It is also used in some paper products such as pipe insulation, wrappings, and other products, including brake linings and gaskets. Group 6.--The main consumption for this group is in asbestos cement products, gaskets, brake linings, vinyl sheet backings, and millboard. Group 7.--The group is used in molded brake linings and clutch facings, as a filler in vinyl and asphalt floor tile, and in asphalt compounds, joint and insulation cements, roof coatings, plastics, and caulking compounds. Amosite is used for felted insulation in blanket form for hightemperature service up to 480C. A loosely compacted form is applied as a covering for marine turbines, jet engines, and similar applications. Amosite is also used as a constituent of lightweight, fire-resistant marine partition board. Long-fiber crocidolite ("blue asbestos") is woven into fabrics for locomotive-boiler lagging and for acid-resistant packings and gaskets. The principal use of the shorter crocidolite fibers is in asbestos cement pipe. ASBESTOS FIBER LENGTHS NUUWTEtS World end-use patterns are not discernible from available data, and the use of U.S. patterns to project usage in the rest of the world cannot be justified. In the 1970's, 70% of the world's asbestos was reportedly connected with products used in the con struction industry. This is expected to continue into the 1980's and can be used for planning purposes. Domestic asbestos-product plants are located principally in the eastern, southern, and west coast areas. Asbestos is adaptable to more than 2,000 uses. Because of its high tensile strength and high temperature resistance, it is used in rockets and missiles. In an unclassified Government stockpile report to the Congress in 1980, the Federal Emergency Manage ment Agency (FEMA) describes the use of asbestos in the pro duction of weapons subsystems including the Army Tow, Lance, Pershing, and the Navy Trident. The Department of Defense re mains vitally interested in the status of asbestos availability because of critical needs for this raw material. SUPPLY-DEMAND RELATIONSHIPS Components of Supply During the entire history of the asbestos industry in the United States, domestic sources have been able to meet only a small percentage of U.S. requirements. Vermont and the Copperopolis district of California have been the only consistent U.S. sources of Quebec-type asbestos. Both are predominantly producers of short fiber, but the Vermont asbestos mines can produce about 500 tons per year of spinning-length fiber. Most of it is applied to nonspinning uses. Canada furnished about 94% of the asbestos tonnage imported by the United States during the past decade, but only a small portion was spinning-grade fibers. The comparatively small quan tities of chrysotile received from Africa, particularly those from Zimbabwe, are mmore important than would appear on a ton nage basis because they consist largely of special kinds and qualities unobtainable elsewhere. Under emergency conditions, imports ofspinning fibers are of primary importance. The longer fibers of chrysotile suitable for spinning represent a small frac tion of the total world production. Shortages of spinning-grade fibers have occurred previously, but no longer seem to be chronic except for certain special grades. U.S. imports of amosite, available only from the Republic of South Africa, averaged about 2,200 tons per year from 1973 to 1983. However, 1983 imports were only 9% of those in 1973. Amosite remains a strategic and critical material with a Govern ment stockpile goal. Imports of crocidolite, also available only from the Republic of South Africa, averaged about 10,000 tons per year from 1973 to 1983. Imports in 1983 were the lowest since 1973 and were only 37% of those in 1978. Economic recession and environmental fears were contributing factors. U.S. and World Production In 1973, U.S. production of asbestos fiber was at an alltime high; however, production had declined by 50% by 1983. Cana dian production of asbestos, all chrysotile, also peaked in 1973, at 1.6 million metric tons and had also decreased by roughly 50% by 1983. The Asbestos Hill Mine in Northern Quebec was closed in 1983 because of the depressed market. The early 1980's have been characterized as a buyer's market with most producers hav ing such high inventories that periodic miner layoffs have been necessary. CTD007105 6 WORLD PRODUCTION JAPAN 4 WORLD TOTAL 4.1ST mineral facts and problems ASBESTOS SUPPLY-OEMANO RELATIONSHIPS-1963 THOUSAND METRIC TONS ASBESTOS 1*4 12 SHIPMENTS Of STOCKPILE EXCESSES 1 90VERNMENT STOCKPILE IV fWTff A II CM KEY E ESTIMATE SIC STANOARO MOUSTRIAL CLASSIFICATION A CNRYSOTtli i crocjooute C AMOSITE Figure 3. Supply-demand relationships for asbestos, 1983. flooring PROOUCTS 45 WBS--------- -- ASSESTOS CEMENT PIPE --stsje ROOFING > PROOUCTS 1 sic an FRICTION PROOUCTS 41 --------- 5T5E ASSESTOS CEMENT SHEET to SIC 3212 PACKING ANO GASKETS 12 SIC 3212 INSULATION 1 1 SIC 3292 PAPER PROOUCTS 2 sic mi TEXTILES 1 SIC 3292 OTHER 42 Tabt# 4.--Asbasto* supply-demand relationships, 1973-83 (Thouaartd metric tons) United States.................................. Rest d world.................................... Total .............. 1973 136 4.060 4.186 1974 99 4.066 4,157 DomtaOc mine*............................ Imports Industry stocks. Jan. 1 ... Total U.S. supply . Distribution at U.S. supply- Industry stocks, Dec. 31 Exports ... Industrial damand ... . 136 719 146 1.000 139 60 601 96 696 139 933 110 56 767 Aabastoa camant pips ............ Aabaatoa camant sheet Coalings and compounds. Floonng products . Friction products Insulation: Thermal Electrical. Packing and gaakats Paper products Plastics Roofing products Tertlas Other . TotaP w M'mwww ** u/ 191/. <0t> do not add to nub blown fiocouoo ot indopondont rounding 1975 89 4,060 1976 105 4,662 1977 1976 1979 WORLD PRODUCTION 92 4,701 93 4.600 93 4,813 1960 X 4,619 4,139 4.767 4,793 4,693 4,906 4,699 COMPONENTS ANO DISTRIBUTION OF U.S. SUPPLY 69 105 92 93 93 X 469 S97 551 570 513 327 110 104 104 40 63 X 688 806 747 703 689 492 104 104 40 63 85 84 33 43 35 42 43 49 551 669 672 619 561 359 U.S. DEMANO PATTERN 115 106 96 27 25 22 36 33 X 150 138 125 57 53 46 42 23 11 70 52 17 15 14 6 443 3 26 25 23 12 776 1 8 77 2 70 64 58 24 10 9 8 2 143 133 121 111 872 619 561 369 1X1 78 4,XI 4,337 78 338 64 498 X 64 349 42 20 13 67 SI 6 1 19 2 1 16 2 IX 349 1962 64 4,016 4,OX 64 242 X XI 86 59 247 X 11 25 49 53 -- 1 14 2 -- 7 1 46 247 1963 70 4.X7 4.157 70 IX X XI 79 X 217 28 10 23 45 48 -- 1 12 6 42 217 clO001A06 ASBESTOS 7 The spinning grades of chrysotile asbestos produced in Zim babwe were of great importance during World War II and the early postwar years because they constituted the principal source of low-iron chrysotile suitable for shipboard electric-cable insula tion. They are of renewed importance as the only current source of substantive amounts of spinning-grade low-iron chrysotile. There are indications, however, that Brinco Mining Ltd. can resume mining of these coveted fibers from newly found resources at its Cassiar Mine in Canada. Production of both amosite and crocidoiite in the Republic of South Africa have decreased significantly because of the economic and environmental factors affecting the entire asbestos industry. U.S. and World Consumption The nine largest uses of asbestos in 1983 were friction products, 22%; flooring products, 21%; asbestos cement pipe, 12%; coatings and compounds, 11%; packing and gaskets, 6%; asbestos cement sheet, 5%; roofing products, 3%; plastics, 1 %; and tex tiles, 1 %. Other products used 18% of the asbestos. Friction prod ucts usage was 79% of that in 1979; flooring products, 37%; asbestos cement pipe, 12%; coatings and compounds, 115%; packing and gaskets, 63 %; asbestos cement sheet, 91 %; roofing products, 9%; plastics, 33%; and textiles, 16%. Dramatic decreases in demand occurred during the past decade for asbestos usage in pipe, roofing, flooring, sheet, and textiles. Consumption in friction products has decreased only slightly since 1973, and this has become the largest end use. Total U.S. con sumption decreased by 73% during the past decade. Total world production, and probably consumption, has changed little during the past decade. Apparently, markets in countries with mature economies have been replaced by some in developing countries. MAJOR ASBESTOS END USES, 1977-83 THOUSAND METRIC TONS FLOORIN6 Ymt 1977 1978 1979 1960 1981 1962 1983 ASBESTOS CEMENT RIFE ROOFING FRICTION PRODUCTS COATINGS AND COMPOUNDS Figure 4 --Trend showing the decline of major asbestos uses during the 1977-83 period. Table below gives end-use data in thousand metric tons. Roofing ISO 138 12S 70 67 49 45 Asbestos cement pipe 115 106 96 42 42 38 26 Roofing products 70 64 56 24 16 7 6 Friction products 57 53 48 52 51 53 48 Costings and compounds 36 33 30 11 13 25 23 CTD007107 MINERAL FACTS AND PROBLEMS World Trade If one were to remove from consideration the asbestos produced in China, nearly all of which is used domestically, that produced in the U.S.S.R., most of which is used domestically or in other Council for Mutual Economic Assistance countries, and Brazil's domestically consumed production, then a truer picture of Cana dian prominence emerges. The world supply breakdown in 1983 then becomes Canada, 50%; the Republic of South Africa, 12%; Zimbabwe, 11%; Italy, 7%; Greece, 6%; and the United States, 4%. Recycling Asbestos libers cannot be recycled in their common role of rein forcing a host matrix because removal from the matrix destroys the fibers. There are few asbestos uses, mainly textile, that have uncom bined fibers in the end product. When these products are no longer useful, neither is the asbestos because physical and/or chemical changes may have transformed it into a different mineral with less strength and/or shorter fibers that are of less value than the reclamation costs. Thus,, asbestos is a nonrecyclable natural resource. Substitutes There is a great and continuing interest among present and potential manufacturers of both organic and inorganic fibers in acquiring some portions of the asbestos market. The environmen tal problems with asbestos make markets vulnerable to substitutes. Few substitutes, however, will be able to meet certain criteria suf ficiently to acquire any substantial part of the asbestos market, even if the substitute is environmentally acceptable. A substitute must approach the strength, chemical inertness, durability, and cost of asbestos. Ironically, the material that comes closest to meeting those criteria uses asbestos as the major raw material. The Quebec Government's Societe Nationale de I'Amiante (SNA) has an asbestos substitute that, if it fulfills initial promise, could meet environmental objections and be substitutable across the board. The new material, "Chrysophosphate," is made by altering the surface characteristics ofchrysodle asbestos by a phosphadng proc ess. Chrysophosphate is claimed to have greatly reduced biological reactivity compared with chrysodle with virtually no change in physical and engineering characteristics and little increase in cost. BYPRODUCTS AND COPRODUCTS Until recent times the only byproduct of record from asbestos production was a carefully designed mix of particle size blend of serpentine rock traction product from Vermont asbestos tailings that was excellent for use on ice and snow. Environmental fears lulled that market. Quebec's SNA, however, views the mountains of tailings from asbestos production as an already mined and variably crushed natural resource. This organization has a magnesium metal plant in operation using this resource. It has also demonstrated that, using the tailings as a sulfur scrubber, a new source of magnesium sulfate is the product of a successful pollution abatement effort at a smelter. STRATEGIC CONSIDERATIONS During World War II, controls were in effect to restrict ex ports of asbestos needed in the military program. These controls Table 5.--Stockpile status, March 31, 1M4 (MMrie tons; Mortal IshseMis Aabaaloa, amotfta... .......... Aabaaaoa. crocktoMa............ Qom 2.722 15,422 0 Total inwantory 754 were removed by executive order on September 10, 1945. Dur ing the Korean war, the supply situadon again became acute, and in 1950 and 1951 controls were invoked that required licenses for export of all grades of asbestos. The license requirement was removed for the nonspinning grades in 1953 and for spinning fibers in 1954; however, export licenses are still required for shipments to centrally controlled economy countries. Chrysodle and amosite are the only types of asbestos having current strategic stockpile goals. The stockpile goal for chrysodle had been reduced to zero in 1976, but a 1977 moratorium on disposals preserved some stock prior to the new goal of 2,722 tons set in 1980. The United States has been historically dependent upon foreign sources for about 90% of its requirements for all grades and types of asbestos. The only current source of low-iron, spinning-grade chrysodle asbestos is Zimbabwe. The only source of commercial grades and quantities of amosite is limited to an area in the Transvaal, Republic of South Africa. The United States is com pletely dependent on foreign sources for croddolite. Although the United States is an asbestos-importing country, there is some ex port trade, because domestic chrysodle producers have a signifi cant markets in Japan and Latin America. There are some re exports of foreign fibers. ECONOMIC FACTORS Prices Depressed markets and high producer inventories of the last few years have caused negotiated asbestos prices to be lower than listed prices. Unit values calculated using import data have more realistically represented the domestic market prices. The average constant dollar value of imported asbestos increased significantly during the late 1970's but then returned to below the 1963 level. The average unit value of exported asbestos was $360 per metric ton in 1983. Tariffs and Taxes No tariffs are levied on imported asbestos, and no special taxes are levied on the asbestos industry. Depletion Provisions Producers are granted a depletion allowance of 22% on domestic production and 10% on foreign production. Table 6.--Customs unit value* of imported asbestos (Dolan par matric ton) 1079 1960 1961 1962 1963 Canada: Camam........ Crude Spinning. . Olher................ South Africa, nopublic ot Croodoltta 236 251 272 234 257 201 158 -- 380 i99 868 643 927 917 932 292 296 373 334 466 1,611 728 771 840 711 686 676 646 CTD007108 ASBESTOS 9 Tabto 7.--'Hmt-pdct ratationaNp# tor import#*! astoastos Yev 1963 1964 1965 1966 1967 1966 1969 1970 1971 1972 1973 1974 1975 1976 1977 1976 1979 1960 1961 1962 1963 Average mull U S producer pned, doiart per metric ton Actual price Bated on constant 1963 doiart 102 307 109 323 106 313 111 312 112 306 109 285 121 301 127 300 130 292 129 278 135 275 135 253 159 273 226 368 274 422 273 391 264 346 281 340 307 339 268 279 278 276 OPERATING FACTORS Environmental Requirements In 1970, Congress enacted the Clean Air Act. A provision of that act allowed the Administrator of the Environmental Protec tion Agency (EPA) to designate substances as "hazardous air pollutants. ' ' One of three substances named to the first list on March 31, 1971, was asbestos. EPA was the first Federal agency to address the growing controversy about the effects of asbestos dust upon the health of humans. There is no consensus about a permissible exposure limit (PEL), or even a method of measuring exposure levels. EPA has indicated that no acceptable method exists to measure asbestos in the am bient air. The Occupational Safety and Health Administration (OSHA) of the U.S. Department of Labor uses a membrane filter and microscopy; the standard PEL is two fibers with an aspect (length to width) ratio of 3:1 or greater and greater than 3 micrometers in length per milliliter of air. The method used by the Mine Safety and Health Administration (MSHA) approaches the OSHA method and uses the two-fiber level. Since 1981, a spate of actions have been taken by the regulatory agencies aimed at minimizing the perceived hazards of asbestos exposure. The following are among the significant ones: In the Federal Register (FR) of May 27, 1983, the EPA pub lished its rule on asbestos in school buildings. Under the rule, inspections and identification of friable asbestos-containing material are required of all public and private elementary and secondary schools. Inspection results must be maintained and communicated to a school's parent-teacher association. Employees must be notified of the location of friable asbestos materials and be provided with instructions on exposure reduction. On July 27, 1983, in'testimony before the Senate Subcommit tee on Toxic Substances and Environmental Oversight, the EPA testified that within 1 year it would propose a ban on certain asbestos products. On February 1, 1985, the EPA announced its intention to refer the occupational safety or consumer risks associated with asbestos to OSHA and the Consumer Product Safety Commission (CPSC). This action, in effect, places on in definite hold EPA's pending proposals to ban certain asbestoscontaining products (asbestos cement pipe, flooring felts, roof ing felts, and vinyl asbestos tile) and the phaseout of the remain ing uses of asbestos over a 10-year period. OSHA published in the Federal Register of November 4, 1983, its Emergency Temporary Standard (ETS), which lowers, by a factor of four, the permissible level of workplace exposure to asbestos. The ETS was challenged in the Fifth Circuit Court of Appeals by the asbestos industry, and on November 23, it was stayed. On March 7, 1984, the court issued the following ruling: "We determine the ETS to be invalid because the record, con sidered as a whole, does not indicate that the risk the ETS seeks to eliminate is `grave, ' as OSHA itself has defined it, or that the ETS is `necessary,' as those terms are used in the ETS statute." By notice in the FR of April 10, 1984, OSHA published its long-awaited proposal to revise the standard for occupational ex posure to asbestos. In addition, OSHA's 1973 proposal was formally withdrawn and replaced by this action. The regulatory text of the proposal is limited to two alternative PEL, 0.2 liber per cubic centimeter and 0.5 liber per cubic cen timeter; requirement for an employee information and training program; and warning signs to be displayed at each location where a revised PEL may be exceeded. OSHA plans to adopt a new PEL, which reflects evidence that will be produced in the record concerning health risk and technical and economic feasibility and which may be higher or lower than the limits proposed--Hear ings on the proposal were held during 1984. As part of a requested review, the U.S. Department of the Interior strongly suggested that the ASTM asbestos definition previously discussed in this report be adopted as the Federal definition. Toxicity There remain many conflicting reports on the health effects of asbestos and conflicts in the evaluation of the validity of such. The few areas of consensus are as follows: 1. Prolonged occupational exposure to heavy concentrations of asbestos dust, in the absence of personal protective devices, can measurably increase the changes of a person contracting a type of pneumoconiosis called asbestosis. 2. Exposure to asbestos may increase the chances of contract ing the very rare type of cancer called mesothelioma. 3. Asbestos workers exposed to heavy concentrations of dust without respiratory protection, and who are also heavy smokers, have increased chances for contracting lung cancer. Employment Asbestos production in the United States has never been great. Reduction to two full-time mines and one part-time mine has not reduced the work force significantly. It is very difficult to judge the effect on the manufacturing plants of the reduction in asbestos use. Employment has been reduced in those asbestos-dependent industries such as asbestos cement pipe. Energy Requirements The Bureau of Mines conducted a comprehensive study of the energy used in the asbestos-mining industry in 1973 (table 8). The survey covered all producers in Arizona, California, North Carolina, and Vermont. Mining conditions have changed little since then. On a tonnage basis, energy used per ton of usable asbestos was equivalent to 1,500 kilowatt hours. Estimated cost was $3.5 million or $25.86 per ton calculated in 1983 dollars. The ease of mining the Coalinga, CA, deposit kept the energy requirements low. Data extracted from a University of Illinois study demonstrate that asbestos extraction energy costs of a large Canadian mine and mill are higher than those of the average U.S. producer (4). Energy requirements per ton were 3,112 kilowatt hours. These data differ from a report from Battelle Columbus laboratories (7), which found the energy used per ton of asbestos produced to be 2,725 kilowatt hours. CTD007109 10 MINERAL FACTS AND PROBLEMS TaU* a.--Enargy uaad by tha U.S. aabaatoa mining induatry Source end unit Heavy fuel oil Natural gas Electricity Dieeel oH Liquid petroleum gas . Gasoline .............. thousand gsNons .. mlon cubic feet thousand kilowatt hours momma gatona do . do Total energy, thousand titavett hours Used m mining 852 -- 2.641 412 14 52 59.192 Used in 1.345 168 44.974 133 168 12 166,994 Total uaad 2.197 168 47,615 546 182 64 226,166 Total (thousand idtowstt hours) 96.356 50.736 47,615 22.147 6,967 2.343 226.166 Tabia 9.--Enargy conaumad In tha production of 1 matrtc ton of ctaanad and gradad chryaotila aabaatoa* Stage and type ot fuel Mirung:> Electric.............................. Dieeel fuel on .................. Bunker6Coi................ Kereeene ................ GaooHne.......................... Total.............................. Primary crushing: Electric . Secondary crushing . Orytng: Electnc. .............. No. 2 fuel oil .. Bunker 6C oil Propane . Total . . Mtfting and grading: Electric Grand total .............. Amount 42 kilowatt hours 1l.12gs6ons 1.46 gtftons 0,04 gatton................ 0.51 gtfton.................. 7 kilowatt hours 75 kilowatt hours .. 42 kiowatt hours___ 0.54 gatton 15.40 QsHons 0.12 gatton 249 kMowstt hours . Equivalent thousand Btu 550 1.652 270 6 77 2,757 67 963 550 90 2.859 13 3.512 3.269 10.606 'Mlna-planl tranapatatton not ndudad. *8aaad on a Ivga Quatoac mlna wtm a 3 to 1 ora ratio, S War par ton ot ora, and 25 to 30 mctiaa of mma ptadprlaHon par yaar. Souroa: Unfvamty of aknoa (5). A study of the energy content of three cladding materials was done in the United Kingdom in 1979 for the Asbestos Informa tion Centre (7). The study started at the mines for the raw materials and ended at the building site. All relevant and signifi cant energy expenditures and credits were calculated. The summary data showed that for each square meter of cor rugated asbestos cement sheet laid, a total of 16.42 kilowatt hours of energy was used, for a square meter of corrugated aluminum sheeting, 68.92 kilowatt hours was used, and for a square meter of plastic coated corrugated sheet steel, 123.5 kilowatt hours was used. PROBLEMS It is difficult to separate environmental and economic causes for the decline in asbestos consumption in the United States and other mature market economy countries. It is true that the con struction industry, which is the largest user of asbestos products, was hit hard by recession in the early 1980's and has yet to fully recover. It is also true that many countries have stopped just short of banning asbestos from the marketplace altogether because of the perceived health effects. If, as some European prognosticators suggested, the decline in asbestos consumption was 70% economic and 30% en vironmental, then a return to a normal economy should result in recapture of 70% of the lost market, an optimistic assump tion. Preliminary 1984 U.S. data reveal a 10% upturn in asbestos consumption. The legal expenses incurred by the asbestos companies are high and act as a deterrent to retention of old markets and capture of new ones. The Manville case is illustrative of the problem. On August 26, 1982, the Manville Corp., formerly Johns-Manville Inc., filed a bankruptcy petition under Chapter 11 of the Federal Bankruptcy Code. Manville at that time was the largest producer of asbestos among the market economy countries, from its Cana dian mines, and the largest manufacturer of asbestos-containing products in the United States. The purpose of the bankruptcy filing was to relieve the burden of 16,500 outstanding lawsuits against Manville in the asbestos-related disease area. Manville was also hopeful of legislative relief, which had, as of yearend 1984, failed to materialize. Since that time, Manville has sold all of its asbestos-producing mines and its asbestos-using manufac turing plants. OUTLOOK The 1965 edition of Mineral Facts and Problems predicted that U.S. asbestos consumption should reach 800,000 metric tons by 1970 and could, in the absence of a recession, reach 900,000 metric tons by 1975. The former was not reached until 1973, and the latter, never. Based on an anticipated healthy economy and with no forebodings of worsening environmental problems, that edi tion predicted that domestic production would continue to sup ply 10% of the Nation's needs. The recessions and environmen tal problems in the intervening years have drastically reduced domestic demand. With lowered demand, domestic production has increased its share of consumption, even with decreasing pro duction, because transportation costs have given it a decided economic advantage over imports. Demand Consistent end-use data are available for only 7 years, not a long enough time series upon which to base a reliable statistical projection. That these 7 years were during periods of environmen tal pressures with some recessionary years exaggerates the downward trend. The forecast was derived by contingency forecasting of the major end-use demands, considering possible shifts caused by changing technology, dwindling resources, and environmental problems during the forecast period. It is impor tant to remember that these forecasts come from the very low 1983 base. It is forecast that domestic asbestos demand bottomed out in 1983 and that year's demand, 217,000 tons, will double by 2000 equal to an average annual growth rate of 4.4%. This is only superficially positive because demand in 2000 would only reach 57% of that in 1973. The rise in 1984 consumption, about 10%, may indicate that some markets may have begun to recover. Rest-of-world demand is expected to show a slightly greater growth than that of the United States because the developing countries have a much greater new construction potential, and probably fewer environmental restraints. This average annual growth rate from 1983 to 2000 is estimated to be 4.5% The low end ol the range corresponds to an average annual growth rate of 3% and reflects a less rapid improvement in living standards in developing countries. About one-half of asbestos consumption in the United States during 1983 was by the construction industry, and this ratio is expected to persist throughout the forecast period. Domestic de- CTD007110 ASBESTOS TaW* 10.--Projection* and forecast* tor U.S. aabeetoe demand bv and (Thousand mmrtc tons) J 2000 11 Contingency forecast for UnNad Q*--rr End uat 1983 Forecast rings Asbestos cement pgie Aibuloi cuntni ihM( Costings and compounds Flooring products Friction products insulation. Pocking and gaskets Papor nmami es ... Roofing products Textiles Othor .................................................. TotaP protections' Low 26 0 10 0 23 6V 45 0 48 2 1-- 12 0 20 10 80 10 42 0 25 0 25 25 50 0 0 0 10 0 0 0 217 - 186 Hqh Probable 150 100 30 16 70 50 90 70 180 120 52 30 10 10 2 50 25 10 5 42 100 43 700 460 'Statistical projections. provided by tha Branch of Economic Analysis. ara danved (ram regression anatyaaa baaad on fryear or 23-year histone* time aartaa data and from forecasts of acononac indicator!, auch aa tha GNP and FRB index. A swtsftcil projection of zero indfcataa that demand wM vanish at or balora tha yaar 2000, baaad on tfw historical raiationahip. Projection aquabona wSh a coefficient of determination <n aquarad) taaa than 0.70 ara indicatad by an tattrtalf n. >Mey not add to totals shown bacauaa of indapandant rounding. Table 11.--Summary of toracaata of U.S. and raet-of-wortd aabaatoa demand, 1990 and 2000 (Thousand nmne Ion) United Stssas: Total . --nest _otCi .wu.--mo. runt.aife! .. Total . Cumulative .. World: ToW Cumulative . . 1963 ..... ................................................. ... .. . ................................. ........................................ .... .......................... .......................................... ........................ ...................................... 217 -- 3.940 -- 4,157 -- 2000 Foracast ranos Low High 186 3.400 6300 88,000 6.686 91.400 700 7.300 12.500 130,000 13300 137,300 Prababl 1990 2000 310 1.900 5.400 33.000 5.710 34,900 450 5.600 6.300 102.000 8,750 107,800 Mngi annual growth rata 1983-2000 (parcant) 4.4 -- 4.5 -- 4.5 -- mand for asbestos in the construction industry was forecast to increase to the year 2000 at an average annual rate range of 0.0% to 3.5% on the basis of total new construction. Asbestos Cement Pipe.--These products, if asbestos for this use is banned, would have a negative growth rate. The low end of the forecast range, though, is thought to be zero growth. The high end could reach nearly 11 % average annual growth rate with improvement of the environmental picture and if the money for needed sanitary and water systems is found. The probable de mand in 2000 should nearly reach the 1977 high with an 8.3% average annual growth rate. Asbestos Cement Sheet.--This product, which could disappear from the marketplace with a negative rate, has, as the high end of the forecast range suggests, a 6.7% average annual growth rate, or will, most probably, recapture lost markets at a 2.8% growth rate. Coatings and Compounds.--Asbestos did not lose its place in this market as seriously as it did in other markets. The fact that the fibers are encapsulated and these products are nonfriable helped. This use could remain virtually static, recapture markets at a 6.8% average annual growth rate or, most probably, advance at a 4.7% average annual growth rate. Flooring Products.--Asbestos in these products could continue to decline at a negative 3.4% rate, respond robusdy to the temper ing of the perceived environmental threat at a 4.2% rate of in crease, or, most likely, recapture markets at a 2.7% average an nual growth rate. Friction Products.--In the total absence of viable substitutes, asbestos uses in these products have responded only to economic, not environmental, pressures. At worst there would be no growth, at best a 7.3% growth rate, and most probably a 5.6% average annual growth rate. Insulation.--Asbestos could lose all of its markets in this area, recover markets at a healthy 14.5% growth rate, or most prob ably recover them at a 10% average annual growth rate. Packing and Gaskets.--Asbestos could lose its entire share of this market to the substitutes now available, recover most of the lost market leading to a 5.6% growth rate, or, most probably, con tinue to lose markets at an average annual negative growth rate of 1.0%. Paper. --Asbestos in paper could easily lose its entire share of this market. Economic and technical factors could, however, with a more objective environmental view, allow the market to respond at a 10% growth rate. A zero growth rate, however, is likely. Plastics.--Asbestos has never achieved the share of this market that its tensile strength and low cost would suggest in these prod ucts, in which it is fully encapsulated. At the least it should more than recapture its former market share and this would require a growth rate of 14.5%. A market in 2000 of 50 times greater than that in 1983 is below some industry forecasts. A market of 25 times that of 1983 seems most probable. Roofing Products.--The asbestos markets in roofing products have declined greatly in recent years. A total loss of market represents the low end of the forecast range. Also possible, as the high end of the range, is market recovery at a 3.7 % growth rate. Most likely is a zero or slightly negative growth. Textiles.--Asbestos in textiles has lost most of the market because of high visibility and perceived peril. Total loss of market is quite possible as is partial recovery at an 8.5% growth rate. Most likely is a 4.2% average annual growth rate. Other. --The many small markets covered here may be the most vulnerable to environmental pressure, and many probably will vanish while new uses may appear. However, the availability of low-cost, short-fiber asbestos in large quantities from domestic CTD007111 12 MINERAL FACTS AND PROBLEMS Tabte 12.--Adequacy of U.S. and world aabeetoa raaarvaa (Thousand metric torn of asbestos) Reserves ...................... .... Cumulative demand, 1963-2000 ............................................ .............................. Untied Stares 4,000 $.600 Rest at world 106.000 102,000 World total 110,000 107.600 sources will likely impact significantly on the mineral filler market for a wide range of end products, particularly in products that must withstand high-temperature or corrosive conditions. Therefore, these markets could vary from total loss to an average annual growth rate of 5.3% or higher, but will most probably have a near-zero growth rate. Adequacy of Supply The United States has been dependent on foreign supplies of asbestos for certain essential and strategic grades. Canada sup plies most of our requirements for chrysotile, with South Africa supplying amosite and crocidolite. Advancing technology in the use of substitutes could shift the U.S. position from heavy reliance on foreign supplies for this mineral. Domestic resources of chrysotile are found mostly in Califor nia, Vermont, and Arizona. Although deposits are known to ex ist also in Montana, Oregon, Wyoming, and a few other States, production from these has been negligible. California has the greatest potential of becoming a substantial producer of shortfiber asbestos. U.S. and Canadian chrysotile resources are more than ample to meet the high end of the forecast domestic demand for the year 2000. Small domestic requirements for amosite will continue to come horn the Republic ofSouth Africa unless deposits ofa similar asbestos are discovered in other countries, or unless adequate substitutes become available at competitive prices, thereby pro viding acceptable options to the consumers. Crocidolite asbestos will also be obtained from the Republic of South Africa, and perhaps from Australia or Bolivia, so long as it remains com petitive with chrysotile. However, substitution is practicable in its end uses, and continuation of a crocidolite supply is not par ticularly critical. Possible Supply-Demand Changes U.S. domestic demand for asbestos is controlled primarily by the perceived health threat. The absence of more stringent en vironmental restrictions on the use of asbestos could significandy increase demand. New potential users of asbestos are currently discouraged by the environmental problem, and it is not expected that demand will ever again approach that of the late 1970's. The concept of again having worldwide scarcities is remote. The pres ent Canadian reserve base assures an adequate supply well into the next century. Possible Technological Progress Litde or no applications research is under way to improve asbestos markets. Large laboratories such as the former one operated by Johns-Manville are no longer supporting this type of research. Quebec's SNA Crysophosphate asbestos substitute may have promise. This reportedly environmentally, safe substitute is fabricated from asbestos. New products are also being developed from asbestos mining wastes by SNA. Lowering the effective recovery cost of asbestos might aid in the marketing of this unique, versatile, and low-cost raw material. Table 13.--Comparison of U.S. MbMtos production and domand, 1963-S3, 1990, and 2000 (Thousand maetc tons) U.S. u.s. Yaar demand production 1963 1964 1966 1966 1667 1666 1666 1970 1971 1972 1973 1974 1975 1976 1977 1979 1979 1980 1901 1962 1963 667 736 721 730 664 741 711 666 666 734 796 766 700 660 606 619 561 366 349 247 217 60 92 107 114 112 110 114 113 119 120 136 103 66 106 92 93 93 60 76 64 70 1960 2000 '310 *460 ITS *86 >62 *80 tprobebls forecast hum table 11. *21-year trend protection. REFERENCES 1. Handle Columbus Laboratories. Energy Use Patterns in Metallurgical and Nonmetailic Mineral Processing (Phase 7--Summary of the Results of Phases 4, 5, and 6). BuMinesOFR ll7(2)-76, 1976, 31 pp.; NTIS PB 261 151. 2. Bowles, O. The Asbestos Industry. BuMines Bud. 552,1955, 122 pp. 3. Burraeister, H.L., and I. E. Matthews. Mining and Milling Methods and Costs, Vermont Asbestos Mines, The Ruberoid Co., Hyde Park, Vt. BuMines IC 8068, 1962, 43 pp. 4. Penner, P., and J. K. Spek. Stockpile Optimization: Energy and Ver satility Considerations for Strategic Materials. Univ. IL, Urbana, IL, May 1976, 97 pp. 5. Quebec Asbestos Mining Association. Asbestos Producer. June-Juiy 1974, p. 15. 6. Ross, M., R. A. Kuntze, and R. A. Clifton. A Definition for Asbestos. Ch. in Definitions for Asbestos and Other Health*Related Silicates, ed. by B. Levadie. ASTM STP 634, Philadelphia, PA, 1984, pp. 139-147. 7. Schatzberger, W.M. Survey of Energy Contents of Three Cladding Materials. Schape Associates Reference 9706, Sept. 24, 1979, 9 pp. SOURCES OF CURRENT INFORMATION Bureau of Mines publications: Mineral Commodity Profile, July 1979. Mineral Commodity Summaries, annual. Minerals Yearbook, annual. Mineral Industry Surveys, annual. Other sources: Company annual reports. Industrial Minerals. Engineering and Mining Journal. World Mining. Mining Engineering. Mining Journal (London). CTD007112