TN 295 LIBRARY OF CONGRESS Q Q 1 3 b b 1 5 :- w f A^* W *P«. C> • c«S$tv^'. o W c5 ^V *^** v .-^i-.%./ , /iSfe- \y .*;& v .-aft'r %./ ' .*^m "v.-j vv .»• .g* V *?xT* a ^ 0* \;V? A :- w • ^ iQ t s '«. *S. A , » * o, " V tl ^-, % » o V"^ > A^^V V ^P '-', &* V -*^T.' A ,^ t • V J^ • ^p :. ^. a* ♦:<{&?»;•. >» .^ * v i °* *^b •1°* wm % & ^ ty v-sBv* vw v™v* %™y V ,/■%. T«i *^^ <0 "T* A. o ♦/'XT* A « •'*- '•"UK-* /°- «, ^^f&Z***!' **Ls A*& » ^„ S? • 4* ** ^o* \* .... V" ' ^ ; V- ' - c ° **£• ° /^*\ /*$&>* /^kS * ^ V^V V^V V^V %-. ■ % * V c<"°, ^ ^ 'o . . • A ^0 V i ' l J 1 !« O, a'* e°" - . :> rat / • / -^K'-- \y .-idfife %y ••»'•• \/ IC 9054 Bureau of Mines Information Circular/1985 Technological Alternatives for the Conservation of Strategic and Critical Minerals— Cobalt, Chromium, Manganese, and Platinum-Group Metals: A Review By Russell J. Foster tftNT^ UNITED STATES DEPARTMENT OF THE INTERIOR 75? *f/NES 75TH At*^ Information Circular 9054 Technological Alternatives for the Conservation of Strategic and Critical Minerals— Cobalt, Chromium, Manganese, and Platinum-Group Metals: A Review By Russell J. Foster 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 I has responsibility for most of our nationally owned public lands and natural resources. This includes fostering the wisest use of our land and water re- sources, protecting our fish and wildlife, preserving the environmental and cultural values of our 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 re- sponsibility for American Indian reservation communities and for people who live in Island Territories under U.S. administration. Library of Congress Cataloging in Publication Data; Foster, Russell J Technological alternatives for the conservation of strategic and crit- ical mineral s— cobalt, chromium, manganese, and platinum-group metals. (Bureau of Mines information circular ; 9054) Bibliography: p. 50-53. Supt. of Docs, no.: I 28.27: 9054. 1. Cobalt. 2. Chromium. 3. Manganese. 4. Platinum group. 5. Strategic materials— United States. 6. Mineral resources conservation- United States. I. United States. Bureau of Mines. II. Title. III. Se- ries: Information circular (United States. Bureau of Mines) ; 9054. TN295.U4 [TN799X6] 622s 85-600141 [333.8'516'0973] For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 CONTENTS Page Abstract Introduction Background The importance of minerals Import dependency and vulnerability Supply-demand alternatives Substitution Processing Recycling Design Domestic supply Foreign supply Ocean minerals Stockpiles Perspectives Cobalt Background Uses and demand alternatives Superalloys Magnetic alloys Cemented carbides Wear-resistant alloys Steels Tool steels Maraging steels Catalysts Paint driers Other chemicals Pigments Ground-coat frit Glass decolorizers , Miscellaneous Supply alternatives Domestic Foreign Ocean minerals Stockpile Summary of demand and supply alternatives , Chromium Background Uses and demand alternatives , Metallurgical , Stainless steels Alloy steels High-strength low-alloy steels Tool steels Alloy cast irons Superalloys . Other alloys , Refractory — chromlte refractories Chemi cals 1 2 2 2 3 4 4 4 5 5 5 5 6 6 6 7 7 8 8 10 11 12 12 12 13 13 14 14 14 15 15 15 15 15 16 17 17 17 18 18 20 20 22 24 25 26 26 26 27 27 28 11 CONTENTS — Continued Page Pigments and paints 28 Leather tanning 29 Metal finishing and treatment 29 Drilling mud additives 29 Water treatment compounds 29 Wood treatment compounds 29 Chemical manufacture and other uses 29 Supply alternatives 30 Domestic 30 Foreign 30 Stockpile 30 Summary of demand and supply alternatives 31 Manganese 32 Background 32 Uses and demand alternatives 34 Metallurgical 34 Iron and steel 34 Nonferrous alloys 37 Batteries. 37 Chemicals and miscellaneous 38 Supply alternatives 38 Domestic. 38 Foreign 39 Ocean minerals 39 Stockpile 39 Summary of demand and supply alternatives 40 Platinum-group metals 40 Background 40 Uses and demand alternatives 42 Catalysts 42 Automotive emission control 42 Petroleum refining 43 Chemical processing 44 Electrical and electronic 44 Contacts 44 Thin- and thick-film circuits 45 Thermocouples and furnace components 45 Electrodes and miscellaneous 45 Glass 45 Jewelry 45 Dental and medical. 46 Miscellaneous 46 Laboratory apparatus 46 Crystal growth 46 Supply alternatives 46 Domestic 46 Foreign 47 Stockpile 47 Summary of demand and supply alternatives 47 Conclusions 48 References 50 ILLUSTRATION iii Page 1. Flowsheet showing manganese inputs for production of steel by blast furnace-basic oxygen process 34 TABLES 1. U.S. consumption of cobalt, by end use 7 2. World cobalt mine production, reserves, and U.S. imports 9 3. Principal U.S. cobalt resources 16 4. U.S. consumption of chroraite, by primary industry 18 5. U.S. consumption of chromium ferroalloys and metal, by end use 19 6. Domestic production and imports of chromium ferroalloys and chromite 20 7. World chromite mine production, reserves, and U.S. imports 21 3. Steel production in the United States, by type of furnace 28 9. Consumption of manganese ore in the United States 32 10. Consumption by end use of manganese ferroalloys and metal in the United States 33 11. Domestic production and imports of manganese ferroalloys and manganese ore 34 12. World manganese mine production, reserves, and U.S. imports 35 13. Domestic manganese resources 38 14. Platinum-group metals sold to consuming industries in the United States... 41 15. Secondary platinum-group metals toll-refined in the United States 41 16. World platinum-group metal production, reserves, and U.S. imports.. 43 17. Total U.S. platinum resources 46 UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT °c degree Celsius mt metric ton °F degree Fahrenheit pet percent ft foot St short ton kW kilowatt tr oz troy ounce lb pound wt pet weight percent ra I meter yr year TECHNOLOGICAL ALTERNATIVES FOR THE CONSERVATION OF STRATEGIC AND CRITICAL MINERALS-COBALT, CHROMIUM, MANGANESE, AND PLATINUM-GROUP METALS: A REVIEW By Russell J. Foster ] ABSTRACT This Bureau of Mines review focuses on the extent to which technologi- cally and economically feasible programs in substitution, improved pro- cessing practices, including recycling, and design can achieve conser- vation of cobalt, chromium, manganese, and platinum-group metals, and thus reduce U.S. vulnerability to interruptions of supply. In addition, supply-side options — domestic and foreign resources, ocean minerals, and stockpiles — are identified. The report consolidates four major studies on these strategic and critical minerals sponsored entirely or partially by the Bureau in the last few years. These studies have been updated with further information from the recent literature. Physical scientist, Branch of Technical Analysis, Bureau of Mines, Washington, DC, INTRODUCTION Recently there has been an increase in public awareness of the importance of nonfuel minerals to the well-being of the United States. The specific issue of strategic and critical minerals avail- ability has generated much interest and controversy, as evidenced by the increas- ing volume of literature and the numer- ous conferences, workshops, and symposia convened on the subject. The Bureau of Mines, as part of its continuing role to identify and analyze problems and poli- cies regarding the Nation's mineral re- quirements, has been an active partici- pant in this area. Always included in any list of stra- tegic and critical minerals are cobalt, chromium, manganese, and platinum-group metals. The United States relies on imports for nearly all of its require- ments for these materials, and most of the principal sources of supply are re- mote and located in regions that have a relatively high risk, of political in- stability. Supply disruptions could ad- versely affect the manufacture of im- portant products for the economy and national defense. Cobalt is used in alloys for strength and heat and wear resistance, as a binder in cemented carbides, for magnetic and catalytic materials, and in paint driers. Chromium is used as an alloying element in stainless and alloy steels, as chro- mite refractories to line high-temper- ature furnaces, and to make chemicals for pigments, plating, and leather tanning. Manganese is important for its desulfu- rizing, deoxidizing, and alloying func- tions in iron and steelmaking; other uses of manganese are dry cell batteries and chemicals. The platinum-group metals ex- hibit several remarkable properties in- cluding resistance to high-temperature corrosion and oxidation, extensive cata- lytic activity, and high melting points, which enable them to be used as automo- tive, chemical process, and petroleum re- fining catalysts; in electrical and elec- tronic devices, dental materials, and jewelry; and for glass manufacturing. The utilization of technological alter- natives — substitution and conservation — presents a means of lessening the vul- nerability of the United States to interruptions of supply. Current essential U.S. cobalt needs are estimated at about 50 pet of present con- sumption. Existing technology is capable of achieving cobalt savings of over 10 million lb annually by the next decade. Present U.S. chromium consumption could be reduced by approximately one-third by using available technology to substi- tute alternative materials and processes, to recover and recycle waste chromium, and to design for greater chromium efficiency. From a practical standpoint there is no substitute for manganese in steelmak- ing. However, the recent adoption of new steelmaking practices has been a major factor in substantially reducing the unit consumption of manganese per ton of raw steel produced. Platinum-group metals exhibit excellent recyclability . Automotive catalytic con- verters represent a considerable source of platinum-group metals, but the low concentration of the metals and the lo- gistics of converter collection are ob- stacles to recycling. Domestic deposits of these minerals would require market prices substantially in excess of those currently prevailing to warrant development. Bringing indi- vidual sites on-stream would generally require several years. BACKGROUND THE IMPORTANCE OF MINERALS The United States requires a continuous and substantial supply of minerals to sustain the domestic economy and maintain the national defense. In 1983 the crude nonfuel mineral production 2 of the United States was valued at $21.1 billion ($19.7 ^Production as measured by mine ship- ments, sales, or marketable production (including consumption by producers). billion in 1982, despite an economic re- cession) . These minerals were used as inputs for products which contributed over $200 billion to the U.S. gross na- tional product. Viewed in the context that a strong economy is essential to facilitate the development of defense materiel and to provide a defense mobili- zation base, it has been stated that "...adequate supplies of virtually every known material are a strategic necessity" U). 3 In a narrower perspective, strategic and critical minerals are considered to be those for which National Defense Stockpile goals have been established. The Strategic and Critical Materials Stock Piling Revision Act of 1979 defines strategic and critical materials as those that (1) would be needed to supply the military, industrial, and essential ci- vilian needs of the United States during a national defense emergency and (2) are not found or produced in the United States in sufficient quantities to meet such needs. Even among the materials in the stock- pile there is a hierarchy with regard to their level of "criticality" ^2 - j>) . Some of the criteria usually considered in- clude the importance of the material to the economy (even a disruption cost that is small relative to the economy as a whole can still be substantial for a given industry or region); importance to the national defense (minerals that are essential to certain defense uses may not play a similar role in the context of overall economic activity); the attendant social and political (noneconoraic) ef- fects of a disruption; demand trends; domestic reserves and resources (cost of exploration, probability of discovery, availability); domestic capacity (mine, processing, fabricating); magnitude of import reliance; foreign supplier coun- tries (number, capacity, accessibility, ideology, political and economic stabil- ity); substitutability (present avail- ability, cost and time to develop); recyclability ; stockpiles (Government, ■^Underlined numbers in parentheses re- fer to items in the list of references at the end of this report. industry). While basic materials such as iron, copper, and lead certainly are of importance to the Nation, others such as cobalt, chromium, manganese, and platinum-group metals assume more prominent positions from the perspective of possible supply problems. IMPORT DEPENDENCY AND VULNERABILITY (_5, 7-10) Since there is no uniformity in the qualitative and quantitative geologic distribution of the earth's mineral re- sources, no country is self-sufficient with regard to mineral requirements. The degree of import reliance varies consid- erably among the highly industrialized nations. The resource policy of the U.S.S.R., for example, has been charac- terized by a willingness to incur sub- stantial costs in order to promote a balanced development of all the materials required by an industrialized society; only when extremely high costs have been encountered has the Soviet Union been willing to accept some degree of reli- ance on foreign supplies (11). Japan, on the other hand, is basically a mineral- resource-poor country, heavily dependent upon raw material imports , and involved in many foreign mineral ventures. The United States has substantial mineral re- sources and has developed a large, multi- faceted minerals industry, but still re- lies in varying degrees on imports to supply a number of minerals, including several used in key sectors of the econ- omy and defense. Although some U.S. min- eral imports are necessitated by inherent resource limitations, others are based on economic advantage. As the Nation's im- port dependence becomes greater, however, in terms both of the number of minerals involved and the percentage of demand that is satisfied by imports, the pos- sibilities for supply difficulties in- crease. Minerals availability problems can result from periods of unusually strong demand, labor strikes, natural disasters, cartel actions, military con- flicts, politically motivated pressures, and internal strife. An additional fac- tor is the concept of a "resources war," which proposes that the Soviet Union, through its influence with certain mineral-producing nations or their adver- saries, may be in a position to selec- tively exert control over the flow of certain strategic and critical materi- als to the United States and its allies. Import dependency in itself is not nec- essarily a problem, but the position changes to one of vulnerability when the need for a material is such that a supply interruption would have severe economic and/or defense implications; the possi- bility of an interruption is enhanced by the actual or potential instability or unreliability of the supplier; domestic resources and foreign alternative supply sources are inadequate; and substitut- ability is limited. The oil embargo ini- tiated by Arab states in 1973 graphically demonstrated the significant impact that a supply shortage of a vital material can have. Likewise, the recent supply and price instabilities in the cobalt market showed that the availability of certain nonfuel minerals cannot be taken for granted. SUPPLY-DEMAND ALTERNATIVES (_5, 12-24) Despite the fact that achievement of self-sufficiency in minerals and materi- als is unlikely for the United States, steps can be taken to lessen import vul- nerability. These steps basically con- sist of reducing consumption through technological options and innovations in the areas of substitution 4 and conserva- tion (improved processing practices, re- cycling, and product design), and assur- ing the accessibility of primary supplies by developing alternative domestic and foreign mineral deposits and through stockpiling. 4 Many analysts discuss substitution and conservation as separate entities, but strategic substitution can be considered as a form of conservation. Although sub- stitution may not reduce the overall use of materials, it can effectively reduce the requirements for a particular mate- rial by shifting the burden to one less critical. Substitution Substitution has both engineering and economic aspects — technical performance and cost effectiveness must be consid- ered. The time needed to develop a sub- stitute and to implement a successful substitution program can be considerable, particularly if new technology also is required. Under normal conditions, sub- stitution is a dynamic displacement pro- cess that occurs over time as a conse- quence of changing conditions such as the relative price of materials, technologi- cal advances, consumer preference, and Government regulation. Substitution is not a viable short-term solution to a sudden material shortage or price escalation unless the substi- tute possesses well-established proper- ties and performance comparable to the preferred material; requires only minimal changes in existing technology and pro- cessing and fabricating facilities; and is readily available at reasonable cost from domestic or accessible, reliable, foreign sources. Substitutes for strate- gic and critical materials rarely meet these criteria — the alternative material usually is less attractive both techno- logically and economically. Essential uses for a material are those that are not substitutable — such a material has a unique chemical or physical property, or functions on a scale or at a price that cannot be met by any other. Processing Losses of material occur at all stages of the materials cycle, from extraction of ore and conversion into intermediate forms, through fabrication of the fin- ished product, to eventual disposal or recycling. Significant losses occur in mining, milling, concentrating, and smelting, as fairly large amounts of ma- terial are discarded in mine and mill tailings and slag, but the cost of fur- ther incremental recovery is relatively high. Therefore, conservation efforts are most often directed at the materials fabrication stage. Of course, in the case of those strategic and critical min- erals where domestic production is non- existent, processing options are effec- tively limited to fabrication. Conservation is especially prominent in the metallurgical area, where the bene- fits of new processing technologies in- clude improving product yield with con- tinuous casting; minimizing alloying element loss through sophisticated melt- ing (vacuum induction melting, vacuum arc remelting, electroslag remelting) and re- fining (argon-oxygen decarburization, vacuum-oxygen decarburization) steps, and surface modification techniques (clad- ding, lining, coating, surface impregna- tion); reducing scrap in fabrication with near-net-shape technology (investment casting, powder metallurgy); and improv- ing quality control. Recycling Recycling offers an opportunity to pro- vide extended or alternative uses for a material. Effective recycling conserves not only the material itself, but in some cases energy as well, and can have the added benefit of improving environmental quality. However, the extent of recy- cling (i.e., home, prompt industrial, or obsolete scrap) depends upon relative primary metal prices, collection logis- tics, and available technology. Barriers in the form of laws, regulations, and policies also can place secondary mate- rials at a competitive disadvantage to their primary counterparts ( 17) . Design Design is a basic determinant of mate- rials use. Products and systems can be designed with an underlying conservation philosophy based on materials critical- ity, reliability, and recyclability , but under conventional circumstances where preferred materials are accessible the designer is concerned primarily with cost and performance considerations. Domestic Supply The development of domestic primary supply capability for strategic and cri- tical minerals offers a far more secure and accessible alternative to unreliable or potentially unstable foreign sources, but establishing domestic mineral produc- tion capacity may not be economically feasible and also can require a great deal of time. Regulations and restricted access to public lands can further deter domestic mineral production. Even if de- veloped, domestic deposits may be capable of satisfying only a modest share of con- sumption and/or may face rapid depletion. Nevertheless, established institutional means, in the form of the Defense Produc- tion Act, exist to provide subsidization of domestic mineral production. Title III of the act specifically authorizes the President to institute and maintain programs of financial assistance for the expansion of domestic production capacity and supply. Foreign Supply The reliability of foreign sources of supply is the crux of import dependency versus vulnerability. Obviously, risk can be minimized by diversifying supply sources among stable, friendly nations where possible. However, ensuring the development of an alternative foreign source of mineral supply and the contin- ued viability of the operation in a com- petitive world market may require direct financial or technical assistance, or a long-term, guaranteed purchase agreement on the part of the United States. In some instances, primary raw materi- als imports are being displaced by im- ports in the form of processed products, such as ferroalloys. There is a clear and accelerating trend for ore-producing countries to convert ore to higher valued intermediate products. This aspect of foreign supply has complex industrial and national security policy implications: Concentration of processed materials capacity outside the United States is leading to further import dependence and possibly vulnerability, and, by displac- ing domestic capacity, is contributing to the erosion of the Nation's industrial base. Furthermore, minerals in the Na- tional Defense Stockpile are of little utility without adequate processing capa- bility. Government options available in- clude domestic conversion of stockpiled ore to intermediate products; import tar- iffs or quotas; and maintenance of a min- imum level of capacity by directed pur- chasing or facility acquisition. Ocean Minerals Much of the interest in unconventional mineral resources — those that differ sig- nificantly from productive deposits in either mineralogy or geologic setting — centers on ocean minerals. Manganese nodules and crusts represent some of the world's largest untapped deposits of im- portant metals. Pacific Ocean nodules typically contain about 0.1 to 0.5 pet Co, 25 to 35 pet Mn, 1 to 1.5 pet Ni , and 1 to 1.5 pet Cu on a dry basis (24); the nodules and crusts off the southeastern shoreline of the United States and south of Hawaii contain less manganese, but some are cobalt-rich. However, the po- tential of ocean mining is clouded with uncertainty. Although technically fea- sible extractive processes exist, the technology and logistics of mining and transport are complex and expensive. Under present market conditions, the economics of developing the mineral re- sources on the ocean floor are unfavor- able, and the unsettled international legal status of deposits outside the Ex- clusive Economic Zone (EEZ) presents a further complication. Stockpiles The availability of materials also can be increased by accumulating stockpiles to be held for release in times of short supply. The National Defense Stockpile, however, exists to supply military, es- sential civilian, and basic industrial needs of the United States during a na- tional defense emergency, and by law cannot be used for economic or budgetary purposes (24) . This greatly limits the accessibility of stockpile materials. Since 1939, there have been 28 releases from the stockpile, but only 4 have oc- curred during peacetime. Some stockpile materials lack immediate usefulness in terms of form if ore is held rather than processed materials without adequate domestic processing capability, and in terms of specifications if material ac- quired years ago has since been rendered obsolete by technological developments. Private industry stockpiling has been proposed as a reliable supplement to the National Defense Stockpile. Consuming companies are intimately acquainted with the materials used in their own manufac- turing processes, so they should be able to privately stockpile materials of opti- mum quantity, quality, and form for their use at any given time. However, when minerals availability is high and prices are low, concerns about stockpiling are minimal. Also, the cost of maintaining large inventories could be prohibitive for the private sector. PERSPECTIVES The issue of strategic and critical minerals availability has evoked a spec- trum of opinion regarding the likelihood and consequences of supply disruptions. The economy of the United States probably could adapt to most supply disruptions, but depending on the material involved, the time required for such adaptation could be lengthy, severe economic dis- locations might occur, and the noneco- nomic ramifications could be of equal or greater importance. The United States has historically been a net importer of several important min- erals, but it is improbable that major inroads into import dependence will be made by the private sector during times when minerals are readily available at low cost. The principal impediment to conservation is that there are few inher- ent incentives other than the economic factors of the market itself. Even mini- mal levels of resource exploration and substitution preparedness are expensive ventures with no assurance of eventual success or utility. However, "on-the- shelf" technology and existing stockpiles (provided that the form and specifica- tions of the stockpiled material are op- timally matched to needs) are the only short-term supply-demand solutions to a disruption. Other technological measures are ineffective if they are not under- taken until the onset of the problem. Therefore, it appears necessary to have continued foresight and awareness of pos- sible materials shortages, and plan con- tingency strategies so that otherwise manageable situations do not become cri- ses because of inadequate lead time. The characteristics and applications of the individual materials themselves will de- termine the optimum approach, but if these strategies involve conservation and substitution research and mineral explor- ation, the Government will have to make a commitment to an active role. Invariably included among the materials considered important to the Nation's in- dustry and defense, and most vulnerable to potential supply disruptions, are co- balt, chromium, manganese, and platinum- group metals. They are discussed indi- vidually in succeeding chapters. COBALT BACKGROUND Cobalt imparts strength and heat and wear resistance to certain alloys. It is also a strongly magnetic element and displays catalytic activity. As a re- sult, cobalt has a number of important uses including superalloys (gas turbine engines), wear-resistant alloys, tool steels, cemented carbides (tools, mining and drilling equipment), magnets, (rotat- ing machinery, indicating meters, tele- communications, loudspeakers), catalysts (petroleum, chemicals), and paint driers. The magnitude of domestic cobalt consump- tion by end use is shown in table 1. The cobalt resources of the United States cannot be considered reserves at cur- rent prices and with existing technol- ogy, and there has been no domestic mine TABLE 1. - U.S. consumption 1 of cobalt, by end use (Thousand pounds of contained cobalt) End use 1981 1982 1983 Quantity pet Quantity pet Quantity pet 4,195 1,687 1,076 488 170 176 254 1,279 1,378 329 441 40 58 109 36 14 9 4 1 2 2 11 12 3 4 .3 .5 1 3,319 1,544 638 446 161 165 201 789 1,114 382 477 32 52 148 35 16 7 5 2 2 2 8 12 4 5 .3 .6 2 4,034 1,711 666 472 248 54 241 1,064 1,503 366 651 41 51 217 36 15 6 Wear-resistant alloys (hardfacing) 4 2 .5 2 9 13 3 6 .4 .4 2 3 1 1,680 100 3 9,468 100 3 11,319 100 In _„J __ _.. ^.-_ Data may not add to totals shown because of independent rounding. Calculated apparent consumption, based on production, import and stockpile acquisitions, and stock changes, was 12.5 million lb in 1981, lb in 1982, and 15.7 million lb in 1983. export data, 11.5 million production of cobalt since 1971. As a result the United States relies on imports for nearly all of its cobalt requirements — net import reliance has averaged over 90 pet for the past sev- eral years — and two of the principal sources of supply, Zaire and Zambia, are remote, developing countries in a region where political instability is a poten- tial risk. Calculated apparent consumption of co- balt in the United States was 15.7 mil- lion lb in 1983, far below the alltime high of 23.7 million lb in 1974. Never- theless, it represented a marked increase over the 1982 total of 11.5 million lb which was the lowest quantity consumed since 1961. The producer price stabil- ized at $12.50/lb during 1983, but the spot-market price was much lower, ranging from $4.75/lb to $6.40/lb. The cessation of stockpile sales of cobalt prior to 1977, and a subsequent period of rapidly increasing demand, eventually led Zaire to initiate an allo- cation program in May 1978. Shortly thereafter, a brief military invasion of Zaire's Shaba Province resulted in a tem- porary shutdown of cobalt operations. Although these events actually had mini- mal impact on cobalt production, con- sumers' concerns for the availability of cobalt sent producer and spot-market prices up dramatically, to $25/ lb and over $40/lb respectively. Subsequent conservation efforts coincided with an economic downturn to significantly reduce cobalt demand, and, beginning in 1981, prices responded accordingly. Despite the recent trend of declining consump- tion, U.S. demand for cobalt is forecast to increase at an annual rate of 2.7 pet from 1981 to the year 2000. The world production of primary cobalt, world co- balt reserves, and exports to the United States are listed in table 2. USES AND DEI4AND ALTERNATIVES Superalloys (24-26) Cobalt is used in many superalloys to enhance their high-temperature properties and processability. With respect to co- balt, superalloys can be classified as cobalt-base (40 pet or more Co) and cobalt-bearing, nickel-base (8 to 20 pet Co). The major use of superalloys is in gas turbines, principally for jet air- craft engines, and to a lesser extent for other propulsion systems, power genera- tion, and gas compression. Much of the alloy substitution that could readily take place occurred during the 1978-80 period. Limited laboratory results from NASA's Conservation of Strategic Aero- space Materials (COSAM) program, which has the objective of minimizing the stra- tegic metal content of vital aerospace components ( 27 ) , have shown that current U.S. superalloys may contain about 50 pet more cobalt than is necessary for most applications, but the potential for using further substitutes for cobalt in super- alloys is limited in the short term, es- pecially for aircraft applications, be- cause of the stringent standards, high costs, and long lead times required to certify substitute alloys. The current engineering of superalloys is dictated more by the need to meet stringent prop- erty and reliability specifications than by economic or conservation considera- tions. With only 200 to 900 lb of cobalt required for a multimillion-dollar jet engine, materials costs will not drive the designer toward an alternate selec- tion unless a parallel alloy and process that can be readily put to use have been established. Otherwise, only a major systems benefit can provide sufficient incentive for change. A ceramic gas tur- bine engine can operate at higher temper- atures and therefore greater thermal ef- ficiency than its metallic counterpart (28). Ceramics also provide improved corrosion resistance and lower density. However, because of their brittleness, ceramics as yet do not offer the dura- bility and reliability required for long- term applications, such as aircraft engines. Many superalloys are used with protec- tive coatings, some of which are them- selves cobalt-rich. The possibility of using other metallic coatings in place of cobalt depends on the particular applica- tion for which the coating is intended. For high-temperature oxidation (oxygen environment) cobalt could be replaced by TABLE 2. - World cobalt mine production, reserves, and U.S. imports (Thousand pounds of contained cobalt) Country Mine output 1981 1982 f 1983 e Reserves U.S. imports 1981 1982 1983 Australia Belgium-Luxembourg Botswana Brazil Canada Cuba Finland France Germany, Federal Republic of Greece India Indonesia Japan Morocco Netherlands New Caledonia Norway Philippines South Africa, Republic of U.S.S.R United Kingdom Yugoslavia Zaire Zambia Zimbabwe Other Total 3,672 560 NA 4,586 3,780 2,280 1,740 814 2,198 4,800 34,000 7,530 220 3,990 560 NA 3,096 3,300 2,050 1,540 598 1,258 5,000 24,920 7,160 220 4,000 560 260 3,492 3,640 2,000 600 1,320 5,200 24,920 7,060 140 50,000 20,000 NA 100,000 400,000 50,000 30,000 40,000 400,000 500,000 300,000 40,000 300,000 20,000 3,000,000 800,000 5,000 NA 83 939 633 1,846 1,206 367 213 1,624 64 87 1,631 464 599 4,176 1,513 149 66,180 53,692 53,192 6,000,000 15,594 169 613 364 1,483 798 336 255 1,024 28 852 266 271 4,971 1,164 276 12,870 168 1,123 400 1,950 1,017 91 79 462 507 707 185 367 7,723 2,347 32 64 17,221 e Estimated. Preliminary . NA Not available, 'Rounded. iron or nickel with little or no loss in usable life. In a high-temperature, sul- fidic corrosion environment, replacement of cobalt would definitely decrease coat- ing service life. Although cobalt-base coatings are used in low-temperature cor- rosive environments, cobalt may not be necessary. Ceramic thermal barrier coat- ings may permit cobalt to be replaced in some environments provided repeated ther- mal cycles can be tolerated. The effect on coatability of decreased cobalt in the substrate alloy also must be considered, but the presence or absence of cobalt in alloy substrates or coatings does not ap- pear to have much bearing on the process- ability of coatings using advanced coat- ing techniques. The superalloy industry generates a high proportion of scrap and waste because of the large number of different and complex alloys produced and the use of composites. Efforts directed at re- ducing the amount of scrap have taken the form of a continuing trend to pro- duction of "near-net-shape" components — substitution of investment castings for forgings and the recent development of powder processing. In addition, modern melting and analytical methods have sig- nificantly reduced off-spec heats; vacuum or controlled atmosphere teeming greatly reduces ingot defects; care is taken to minimize the quantity of material removed with end crops, edge trimming, and fin- ish conditioning. These are evolutionary changes already well under way that may reduce the actual quantity of in-house scrap produced by 25 pet. The best opportunity for significant further 10 reduction in scrap is the adoption of near-net-shape processing for a wider variety of shapes and components. Scrap recycling is an established practice in the superalloy industry. The materials recycled are solid metallic scrap from primary production sources — the predomi- nantly clean, well identified solids and processed turnings which are relatively easy to collect, handle, verify (compo- sition), and melt. However, approximate- ly 40 pet of wrought superalloy scrap and 50 pet of cast superalloy scrap is not directly recycled domestically for pro- duction of these alloys. It is down- graded for use in the steel industry, lost, or exported. Dusts, grindings , furnace scale, and pickle sludges are often mixtures of every alloy produced in the plant and hence are low grade, finely divided, and costly to dry, with inher- ently limited use for recycling. Obso- lete scrap solids are not efficiently recycled — turbine components may become contaminated in service with elements such as lead and sulfur that are highly detrimental to superalloy properties; separation of superalloy components that have been fabricated into more complex assemblies by welding, brazing, or coat- ing can be difficult; the collection of obsolete scrap on a small scale pre- sents logistical difficulties. The best prospect for improving cobalt recovery for use in superalloys is improving the efficiency of recovering obsolete solid scrap, and it is likely that a greater proportion of obsolete scrap solids will be directly recycled in the future. How- ever, a significant amount will continue to be downgraded — a number of processes for separating individual elements from complex superalloy scrap have the ability to recover some or all elements in a pur- ity suitable for use in superalloys, but commercial-scale plants are marginally economic. Magnetic Alloys (24-26) Cobalt is the strongest magnetic ele- ment. It increases the saturation mag- netization of iron and has the high- est Curie temperature known. Therefore, permanent magnets made with cobalt are generally superior. The principal magnet applications are rotating machinery, in- dicating meters, telecommunications, and loudspeakers. The largest use of cobalt in magnetic devices is in Alnico perma- nent magnets (alloys of iron, nickel, cobalt, aluminum, and lesser amounts of other elements) . Together with iron- chromium-cobalt deformable magnets they total about 90 pet of cobalt used in mag- netic applications. Iron-chromium-cobalt alloys offer magnetic characteristics nearly identical to Alnico but at much lower cobalt content. These types have a magnetic energy density 3 to 4 times greater than that of Alnico with only double the cobalt content and are well suited for small, high-torque, fast- response, electric motors. Soft cobalt- containing magnetic materials (e.g. , 2V Permendur, Supermendur) find minor use in aircraft generators and telephone re- ceiver diaphragms; semihard cobalt-con- taining magnetic materials (e.g., Remen- dur, Nibcolloy) find minor use in reed switches, memory applications, and hys- teresis motors. A number of parameters must be consid- ered when magnetic materials are speci- fied for any given application — magnetic strength, size, operating conditions, and cost. Yet, the magnetics industry has reduced its dependence on cobalt through the use of low- or no-cobalt substitutes more than any other industry. Hard ferrites (ceramic magnets) have virtually replaced Alnicos in all large loudspeakers. For smaller speakers iron- chromium-cobalt magnets are feasible, and for the smallest speakers rare earth- cobalt magnets have merit, but further substitution is unlikely at current co- balt prices. Modest substitution could occur at 3 times current prices, but even at 10 to 20 times current prices about 10 to 20 pet of the loudspeakers would still require cobalt. Rotating machinery utilizes primarily permanent magnet generators, motors, and magnetos. Hard ferrites are widely used up to 10 kW power because of cost effectiveness. Greater than 10 kW pow- er demands high-energy-density magnets, 11 particularly rare earth-cobalt. At a tenfold cobalt price increase strenuous efforts would be made to use cobalt-free, or cobalt-efficient, materials, or possi- bly revert to electromagnetic designs, although about 10 to 20 pet of the market could justify cobalt. The designs of certain instruments and indicating meters are closely tied to specific materials. Only at 10 times the present cobalt price would the use of more cobalt-efficient materials occur, and the development of new meter designs operating on different principles be considered. In the field of telecommunications the potential for less cobalt use is sub- stantial. Technological changes such as miniaturization, large-scale integration, digital signaling, and photonics will greatly reduce cobalt requirements. The magnetic industry makes effective use of home or runaround scrap generated during magnet manufacture, but there is little recycling of obsolete scrap except large magnets in scrapped equipment and magnets in leased equipment such as tele- phones. Public utilities could do the same with damping magnets in watt-hour meters , but cobalt prices would have to increase at least threefold. The pri- mary barriers to recycling are identifi- cation and collection of obsolete scrap from widely dispersed locations and the cost of removing small components from scrapped units. Cemented Carbides (24-25) Cobalt is used as the binder in the structure of cemented tungsten carbides in amounts ranging from 3 to 25 pet. These alloys are characterized by excep- tional combinations of hardness, tempera- ture and abrasion resistance, high elas- tic modulus, strength, and toughness, and are widely used in tools for machining cast iron and nonferrous metals, metal forming, raining, oil and gas well drill- ing, and a variety of highly stressed structural applications. In machining ferrous metals, additions of titanium carbide, tantalum carbide, and colura- bium carbide are employed to improve the cutting tool's resistance to chip erosion ("cratering") and to the effect of high cutting-edge temperatures generated dur- ing the machining operation. Substitution of other binder metals and alloys in cemented carbides has received the concentrated attention of researchers over the past 60 yr. In certain cemented carbide alloys designed to combat com- bined corrosion and abrasion, nickel and iron have shown the most promise as substitutes with chromium additions to impart corrosion resistance. Titanium carbide-base cemented carbides commonly containing nickel as the binding metal have found an important but small and specialized field of use. The same is true of aluminum oxide-base ceramics and titanium carbide-aluminum oxide "cer- mets." Other materials receiving atten- tion for specialized uses include silicon nitride as a base compound for cutting tool materials and polycrystalline dia- mond and cubic boron nitride cutting tools for specialized areas of metal and composite material cutting. However, these are not capable of mass replacement of cobalt-bearing cemented carbides with- out an unacceptable loss of productivity and economy in metal cutting because of their brittleness and low cutting-edge strength. Coal and hard-rock mining and oil and gas well drilling applications depend on the unique combination of prop- erties possessed by tungsten carbide- cobalt alloys. Cobalt remains the supe- rior binder, and there are no apparent practical alternatives available or in sight today. The same is true for cer- tain metal-forming and superpressure ap- plications. Research on replacements for cobalt as a binding metal is primarily motivated by the desire to improve prop- erties (corrosion resistance) of current- ly available alloys, and to reduce risks associated with dust exposure. Virtually all cemented carbide manufac- turing scrap is recycled. However, obso- lete scrap recycling is less extensive because of the wide dispersion of carbide users. Nevertheless, direct recycling of obsolete cemented carbide scrap has be- come established with several process routes available. The current practical 12 limit of cemented carbide scrap that is recycled ranges from 15 to 80 pet depend- ing on the application. Although theo- retical maxima can reach 65 to 95 pet, the probable practical limit is estimated at 40 to 85 pet. Wear-Resistant Alloys (24-26) The composition of the most commonly used wear-resistant (hardfacing) alloys is 50 to 70 wt pet Co for application in automotive engine valves, fluid valves, knives, cutters, erosion shields, hot- working dies, and bearing surfaces that cannot be lubricated. The mode of wear — abrasive, adhesive, or erosion — deter- mines the criticality of cobalt use. Cobalt offers important performance bene- fits against galling and cavitation ero- sion wear, but alloys with lower cobalt levels provide alternatives. For erosion from particle impingement there also ex- ist opportunities for alternative alloys with lower or no cobalt. Nickel-base al- loys are gaining in hardfacing of automo- tive engine valves and valve-seat in- serts. The nickel-base properties are comparable or better, are lower cost, and are more easily processed as powder. However, at current cobalt prices there is little incentive to replace high- cobalt wear-resistant alloys with alter- natives. In addition, the performance of cobalt alloys is well established. Should cobalt prices increase, so would the incentive for substitution. At 10 to 15 times current prices, efforts to use substitutes would sweep all areas of wear application, and up to half the cobalt currently used could be conserved. Hardfacing and coating alloys are often utilized as powder metallurgy products deposited as plasma or flame-sprayed pow- ders. The system typically does not re- cycle the overspray, the scrap, or hard- facing or coating material from obsolete parts. Hardfacing rod made by continuous casting and typically used in valve seats and components for diesel engines is not recycled once the seats are taken out of service because of high iron contamina- tion, since the alloy is hardfaced onto an iron substrate. Steels Tool Steels (24-26, 28 ) Tool steels are metallurgically com- plex with six or more major alloying ele- ments and a large number of commercially recognized compositions. Raw materials represent a fraction of overall produc- tion costs because of the special pro- cessing involved, so improved performance can often justify the use of high-cast materials. The heat generated in the machining of some materials (stainless steels, superalloys, titanium alloys), can soften the tool steel so that per- formance deteriorates. Cobalt is added (5 to 12 pet) to high-speed tool steels to increase attainable hardness and im- prove hot hardness and hardness reten- tion, thus improving tool life. Except for high-speed tool steels the only cobalt-bearing standard grades of tool steels are hot-work and cold-work tool steels, and the amount of cobalt in them is minor compared to the high-speed tool steels. Comparable cobalt-free high- speed steels have been developed, so the presence of cobalt is not essential, and its use can be determined by economic considerations. The development of coat- ings (titanium carbide, titanium nitride) that increase tool life also will mini- mize the need for cobalt-bearing steels. Opportunities for reduction of scrap generated during conventional processing are limited. New processing methods, such as electroslag remelting, have pro- vided better product yield and hence less scrap. Further improvement in yield can be expected from the adoption of semicon- tinuous casting of intermediate-size bil- lets, or powder metallurgy, but neither process comes close to entirely eliminat- ing scrap. Although a substantial por- tion of tool steel scrap is recycled, the efficiency of recovery of the alloying elements is significantly lower than with superalloys. Almost all solid in-house scrap and prompt industrial scrap solids are separated by grade and recycled (re- melted). Some obsolete scrap, primar- ily large monolithic industrial cutting tools, is also recycled. Particulate 13 scrap such as furnace dust and mill scale is generally collected with other tool steel and alloy steel wastes produced by the mill, but oily grindings produced by tool fabricators are not recycled because of their high residual phosphorus con- tent, which is unacceptable to tool steel manufacturers. Theoretically all tool steel scrap could be carefully identified during collection and recycled directly or after further processing. However, the fact that it is so often mixed with much lower grade scrap makes more effi- cient collection impractical. Improved sorting and identification techniques have made it possible to recover virtual- ly all solid scrap for recycling directly within the mill. Research aimed at de- vising methods of treating tool steel grindings to make them suitable for recy- cling is underway. Procedures for recov- ering mixed alloy sludges generated by electrical discharge machining processes are also likely to be developed in the next few years. Some work has been done on the chemical separation of the ele- ments in tool steel scrap, but this may be too costly except in times of severe shortage, and there would be a 3-yr lead- time factor. Maraging Steels (24) Maraging steels (predominantly nickel, cobalt (7.5 to 12 pet), molybdenum, and titanium) had initial applications in ultra-high-strength materials with good toughness for use in the aerospace in- dustry, but are now used for tools and other structural applications as well. A cobalt-free alloy containing more tita- nium than the original alloy was recently developed and shows properties consistent with those of the cobalt-bearing grade. Therefore, cobalt is not essential, but for aerospace applications, time-con- suming and costly qualification testing would be required before substitution could be made. Catalysts (24) The catalytic activity of cobalt is utilized in several chemical and petroleum refining processes. Hydro- treating processes utilize 8 to 11 wt pet molybdenum and 1.5 to 3.5 wt pet cobalt (or molybdenum and nickel) on an alumina support to remove sulfur, nitrogen, and metals (typically vanadium and nickel) from various petroleum streams. As the fundamentals of catalysis are better un- derstood, and the quantifiable physical and chemical characteristics can be bet- ter correlated with measures of perform- ance, the same results will be obtainable with lower metals content. Molybdenum- nickel catalysts are widely used in a variety of hydrotreating processes and are more effective than molybdenum-cobalt catalysts for denitrif ication and hydro- gen uptake, whereas molybdenum-cobalt shows higher desulf urization activity. A significant portion of molybdenum-cobalt catalytic applications could use nickel without any substantial process penalty. So far, reclaimers have taken out only molybdenum and vanadium from spent cata- lysts, but plants with the capability to recover essentially all the cobalt from any type of catalyst are envisioned. Re- fineries also are gradually increasing the practice of catalyst regeneration — cleaning up spent catalyst and returning it to useful life. Hydrof ormylation reactions produce C 4 to C13 alcohols. C4 to C5 alcohols are used as solvents; the higher alcohols are further processed to produce plasticiz- ers; some C j 2 alcohol is used to make detergents. The oxo process reacts ethy- lene or propylene with carbon monoxide and hydrogen over a cobalt catalyst (as a soluble salt) to form these linear alcohols. These alcohols are also avail- able from the same process using a rho- dium catalyst, as well as via an alter- nate route (Ziegler-type oligomerization) which uses catalysts other than cobalt. Oxo alcohol catalysts are recycled, bu«_ eventually buildup occurs on the process equipment, requiring that the material be reclaimed. About 90 pet of the cobalt is now being reclaimed, and the remainder is lost in handling. Terephthalic acid and dimethyltereph- thalate are produced from paraxylene for use in the production of polyester fibers 14 and films. The oxidation steps in the reaction are promoted by a cobalt-manga- nese catalyst. There does not appear to be a substitution alternative to cobalt in this process. There is recycling of the catalyst, but as byproducts build up, the catalyst is withdrawn and cobalt- containing sludge is incinerated and sent out for reclamation of cobalt. As a ma- jor user installs incineration facili- ties, the amount being reclaimed will increase to 90 pet. Pyrolysis gasoline is the byproduct of the process used to make ethylene and propylene by thermal or steam cracking of hydrocarbon feedstocks. Pyrolysis gaso- line is catalytically treated in two stages to saturate the olefins present and to remove sulfur; cobalt catalysts are used in the second stage. Nickel- molybdenum catalysts can also be used for pyrolysis gasoline processing. There is currently no reclamation of cobalt from pyrolysis gasoline catalysts. The production of some organic acids also uses small quantities of cobalt cat- alysts. Acetic acid produced via high- pressure methanol carbonylation uses cobalt acetate and iodine as catalysts; adipic acid production uses cobalt naph- thenate or stearate in the first oxida- tion step; benzoic acid production may also use a cobalt catalyst. Many other routes to organic acids are in commercial practice so the use of cobalt can be cir- cumvented. The status of reclamation of organic acid catalysts is unknown. Possibilities exist for increased use of cobalt catalysts in hydrotreating and shale oil processing, but it is possible to use nickel catalysts in place of co- balt in these processes with nearly equi- valent results. Paint Driers (24-25) The role of cobalt in oil-base paint formulations is that of a catalytic agent surface drier. The drier is usually de- rived from cobalt metal reacted with an organic acid in water for chemical re- activity and dispersed in mineral spirits for physical solvency and convenient liquidity at concentrations of 6 to 24 pet Co. The function of the organic acid is to form a cobalt soap that is solu- ble in the diverse range of paint media with minimal concomitant detracting prop- erties for the particular application. The drying process involves the conver- sion of the liquid to a solid by a chem- ical oxidation mechanism. Cobalt soap is usually preferred over manganese, ce- rium, iron, and zirconium soaps in the class of "top driers" in terms of speed of reduction and disappearance of sur- face tack, product discoloration, and durability. Top driers are complemented by "bottom driers" (usually soaps of lead, zinc, calcium, potassium, or zirco- nium) which hasten the solidification of the liquid coating down through the film to the substrate. Cobalt is the most effective surface drier additive in oil-base paints. The amount of cobalt used is typically 0.05 pet (range 0.01 to 0.05 pet). To attain the same drying speed more manganese is usually needed, but this results in more discoloration and poorer durabil- ity. Iron has been used only where its inherent brown hue is acceptable. Ce- rium and zirconium have some favorable properties, but none is an alternative to replace cobalt directly on a one-to- one basis. Replacement is hampered not only by the complexity of the chemical mechanisms of paint formulation and deg- radation, but also by the vast diversity of types of paints. If cobalt were eli- minated or reduced there would be attend- ant costs in convenience and product quality in most cases. The dissipative nature of the product obviously precludes reclamation. Other Chemicals (24) Pigments Cobalt aluminate and silicate and asso- ciated oxides of other transition met- als provide a range of violet, blue, and green inorganic pigments, with ultimate resistance to high heat, light, and bleeding (organic solubility) , as well as special infrared reflectance. Mili- tary insignia and camouflage command high priorities for cobalt colors. With the exception of camouflage, all other 15 uses could be manganese and are potential applications . considered nonessential; other transition metals substitutes in several tapes; cobalt oxide is used for varistors and thermistors. Rubber Tires Ground-Coat Frit Cobalt oxide (0.1 to 1 pet) is used by the porcelain enamel industry to en- hance the adhesion onto metal of alkali alumino-borosilicate glasses, which are ground into frits. Cobalt-base frit is the preferred coating, but there has al- ways been some nickel oxide used along with the cobalt oxide. The cobalt oxide component can be diminished and the nick- el oxide component increased, but frits made with very low cobalt oxide content and high nickel content display inferior durability. Glass Decolorizers Cobalt is used to neutralize the color- ing of impurities such as iron and chro- mium in an average glass batch. Cobalt is needed where glass has to be optically clear. Miscellaneous Accelerators and Stabilizers rated polyes- laminates , and izes a 12-pct a promoter to e and related laminates have cobalt because lightly higher The production of unsatu ters for use in gel coats, compression moldings util cobalt octoate solution as influence the time of cur properties. Gel coats and the more critical need for they cure at ambient or s temperatures . Animal Feeds Cobalt has been used as a trace mineral diet additive in the United States for cattle, sheep, hogs, and poultry to en- able the animals to generate vitamin B 12 for increased growth. Electronics In electronics, soluble cobalt salts are used for magnetic audio and video In the manufacture of steel-belted ra- dial tires, the presence of cobalt en- hances the adherence of rubber to steel. Battery Manufacturing Cobalt imparts improved recharging characteristics to power cells and nickel-cadmium batteries. Other Minor Chemical Uses Cobalt chemicals are also used in small quantities in several other minor uses: electroplating and electroref ining, des- iccant indicators, nucleating agents in investment casting, promoters in water treatment, chemical fuels, components in special oil drilling muds, etching tool steels, printing inks, and fertilizers. Cobalt used as chemicals other than catalysts could be reduced by 20 pet without much difficulty. Further reduc- tions could come from the rubber tire and battery sectors. However, some uses do require cobalt to accomplish the desired effect. Consumption of cobalt in the "miscellaneous" category could be reduced by 40 pet without serious consequences. Overall, a reduction of 60 pet could be achieved for "other chemicals." SUPPLY ALTERNATIVES Domestic (24, 29-30) The Bureau of Mines has evaluated 24 domestic cobalt-bearing deposits with re- gard to the feasibility of cobalt recov- ery either as the principal product from sulfide or nickel-cobalt laterite occur- rences, or as a byproduct of lead or copper. Six of these sites are active mines, all currently producing lead in Missouri, but no attempt is made to ex- tract the cobalt contained in the ore; instead it is lost to the tailings and slag. Cobalt recovery would require the addition of another process circuit and incur added smelting and refining costs. 16 Basically, the technology exists to pro- duce primary cobalt from domestic sources, but the Bureau has concluded that higher prices (cobalt, $25/lb; cop- per, $l/lb; lead, $0.40/lb) are neces- sary to supply a significant percentage of U.S. cobalt consumption. Not only are the economics presently unattractive, but the time required to bring new domestic mines into production has been estimated at 5 yr or more. If circumstances even- tually do favor cobalt production in the United States, two relatively high-grade deposits which have been mined for cobalt previously, the Blackbird Mine in Idaho and the Madison Mine in Missouri, are considered to be likely candidates for development (table 3), but intensive min- ing efforts would rapidly deplete these modest resources. Despite current prices, California Nickel Corp. recently announced plans to build a demonstration plant in 1984 to extract nickel and cobalt from its nickel laterite deposit near Gasquet Mountain, CA. Construction of a commercial-scale plant is planned for 1987 (31). The U.S. Air Force, seeking to develop a secure source of cobalt suitable for use in mak- ing superalloys, has been considering re- questing proposals for a pilot plant to process native cobalt ore (32) . The only cobalt refinery in the United States at present is owned and operated by AMAX, Inc. , in Louisiana with a capacity of 2 million lb of cobalt annually (33) . The refinery treats foreign cobalt-containing nickel matte. A Bureau research effort indicates that the heap-leaching method of recovering copper, which currently accounts for about 18 pet of U.S. copper production, may provide an opportunity for cobalt ex- traction. Passing the leach solutions through resin columns, washing with sul- furic acid, and extracting with solvent produces a concentrated cobalt solution. Further Bureau work will focus on the economic feasibility of the process (34). Foreign (24, 30 ) Cobalt is almost universally recovered as a byproduct of other mining and refin- ing operations , so the potential for in- creasing cobalt output is ultimately lim- ited by the economics of the metal of principal importance. The historic price levels of 1978-80 provided an incentive for increasing byproduct capacity, espe- cially from nickel resources. The copper mines of Zaire and Zambia remain the most important sources of world cobalt production, together provid- ing about 60 pet of the total. Zaire possesses the richest cobalt ores in the world (0.3 to 0.5 pet). Zambian ore grades range from 0.1 to 0.2 pet, and ac- cumulated copper smelter slags grade out at 0.6 pet, presenting another potential, although currently uneconomic, source of supply. Most of the remaining cobalt production from market economy countries is a by- product of nickel sulfide and laterite mining in Australia, Canada, the Philip- pines, Botswana, and New Caledonia; a great deal of New Caledonian cobalt is now lost because of the production pro- cess, which yields ferronickel. Some of the Canadian production is refined in Norway, while all of the cobalt from the other four sources is exported to Canada, Japan, France, or the United States for refining. Finland's cobalt production is derived from both copper and nickel sources , while the Republic of South Africa extracts some cobalt from plat- inum-group metal operations. Morocco had been producing cobalt as a principal product, but reserves there have been virtually depleted. TABLE 3. - Principal U.S. cobalt resources Location Owner and/or operator Ore grade, pet Blackbird Mine, Hanna Mining Co., 0.55 Idaho. Noranda Exploration Inc. Madison Mine, Anschutz Uranium Corp. .25 Missouri. 17 Nickel sulfide ores currently represent the major source of cobalt from which production could be increased in the near future, but the large cobalt resources in nickel laterites, occurring mainly in New Caledonia, Indonesia, the Philippines, and Cuba, could eventually become the most important land-based source of co- balt. Of all the North American cobalt resources, Canadian nickel deposits have the greatest potential for being competi- tive alternatives to existing cobalt sup- ply sources. Ocean Minerals (24) Deep-sea manganese nodules typicalLy contain 0.1 to 0.5 pet Co. Marine manga- nese crusts, some containing perhaps 1 pet Co at relatively shallow depths (less than 2,500 m) , have been located in the Pacific Ocean south of Hawaii, and in the Atlantic Ocean off the southeastern shore line of the United States. Assess- ments of these occurrences are in pro- gress. The current impediments to ocean mining have been discussed previously. Stockpile (30) In 1981 the General Services Admini- stration (GSA) purchased 5.2 million lb of cobalt from Zaire for the National De- fense Stockpile. By yearend 1982 deliv- ery was completed. In 1983 GSA purchased 6.5 million lb of cobalt for the stock- pile, with delivery expected to begin early in 1984. Zaire will supply 4 mil- lion lb and Zambia the remainder, all at $5.50/lb. GSA awarded a contract for an additional 0.5 million lb at S11.70/lb to Inco, Ltd., of Canada in 1984 (35) . A panel of industry experts assembled by the American Society for Metals at the request of the Federal Emergency Manage- ment Agency determined that the recently acquired cobalt meets the quality re- quirements of current technology for the most critical defense and industrial ap- plications, but the present condition of the cobalt purchased during 1947-61 pre- cludes its use for producing vacuum- processed alloys. However, domestic ca- pability (process and equipment) exists to upgrade the quality of the pre-1980 cobalt (36). SUMMARY OF DEMAND AND SUPPLY ALTERNATIVES The price increases of 1978 caused a substantial reduction in the amount of cobalt used in applications where eco- nomic alternatives were readily avail- able. Another round of high prices would lead to further substitution, but not with the facility experienced previously. Current essential U.S. cobalt needs are estimated at about 50 pet of present consumption. Existing substitution, pro- cessing, recycling, and design technology is capable of achieving cobalt savings of over 10 million lb annually by the next decade, based on an estimated consumption level of 22 million lb. Significant amounts of cobalt in super- alloys could be replaced, but this would require costly and time-consuming alloy optimization and engine certification programs . A great deal of substitution for cobalt in magnetic applications has already oc- curred. An estimated 20 pet of current cobalt use in these applications is es- sential and would continue at even a ten- fold price increase. Cobalt is a key requirement for ce- mented carbides, which are critical to high productivity in metal cutting and forming, mining, oil and gas well drill- ing, and other industrial operations. Cobalt-free materials cannot be consid- ered as practical general alternatives. In wear-resistant applications cobalt is required only for protection against galling and cavitation erosion, and even for these uses lower cobalt substitutes will suffice. Cobalt-free grades of high-speed tool steels and maraging steels have been developed. Hydrotreating is the catalytic process most amenable to substitution by cobalt- free materials. Cobalt is the single most effective surface drier additive in oil-base paints. Elimination or reduction of co- balt would incur substantial penalties in convenience and product quality. 18 A 60-pct reduction in the amount of co- balt used in other chemical applications could be accomplished. Most in-house and prompt industrial scrap is recycled, and cobalt is gener- ally recovered. Obsolete, low-grade, and mixed alloy scrap is not efficiently recycled. Some better quality obsolete scrap is recy- cled for superalloys, but a large quan- tity is downgraded. Most low-grade scrap (dusts, mill scale, grindings) is down- graded also, and its cobalt content is lost. Treatment of mixed-alloy scrap to recover all contained elements is tech- nically feasible but not economically practicable. Near-net-shape technologies can achieve improved yield of usable product from raw materials. Zaire and Zambia should continue to be the dominant suppliers in the world co- balt market. The technology exists to produce cobalt metal from domestic deposits, but total production costs would be at least $20/ lb to $25/ lb, and the time required would be at least 5 yr. Of all the potential North American co- balt resources, Canadian nickel deposits have the greatest potential of being com- petitive alternatives to existing cobalt supply sources. CHROMIUM BACKGROUND The uses of chromium encompass three major areas — metallurgical (as an alloy- ing element that imparts a variety of im- portant properties to many ferrous and nonferrous alloys, principally stainless and full-alloy steels) , refractory (chro- mite refractory bricks to line metallur- gical furnaces, glass regenerators, and rotary kilns) , and chemical (mainly pig- ments , plating, and leather tanning). Tables 4 and 5 quantify these uses. Pro- duction of chromite ore in the United States ceased after 1961 (except for a small amount produced for export in 1976), and at present, domestic chromite resources are considered to be uneconomic to develop. Therefore, all chromite con- sumed in the United States is imported, mainly from the Republic of South Africa and the Philippines. Historically chro- mite has been classified into three general grades associated with the major end-use categories , but considerable in- terchangeability among the grades has evolved. Current nomenclature reflects the composition of the ore (high-chro- mium, high-aluminum, high-iron) rather than end use. In addition to chromite, substantial quantities of chromium are also imported as ferroalloys, predominantly high-carbon f errochromium, which is the typical form used to add primary chromium to steel. World ferroalloy production capacity has been shifting to ore-producing countries. As a result, imported chromium ferro- alloys have been steadily increasing their share of total chromium imports relative to chromite, and of total U.S. chromium ferroalloy supply at the ex- pense of domestic production (table 6), a trend which threatens the viability of the U.S. ferroalloy industry. TABLE 4. - U.S. consumption of chromite, by primary industry 1981 1982 1983 Industry Gross weight , 10 3 st Average Cr 2 3 , pet Gross weight, 10 3 st Average Cr 2 3 , pet Gross weight , 10 3 st Average Cr 2 3 , pet 503 148 238 35.7 37.3 42.6 270 80 195 35.1 36.4 44.9 64 72 189 39.3 36.9 44.7 889 37.9 545 38.8 325 41.9 19 TABLE 5. - U.S. consumption of chromium ferroalloys and metal, by end use (Thousand short tons, gross weight) End use Ferrochromium Ferrochromium silicon Metal and other Total I 1981 Carbon steel Stainless and heat-resisting steel. . Full-alloy steel High-strength low-alloy and electric steel Tool steel Cast iron Superalloys Welding materials (structural and hardf acing) Other alloys Miscellaneous Total' Chromium content 1982 Carbon steel Stainless and heat-resisting steel.. Full-alloy steel High-strength low-alloy and electric steel Tool steel Cast iron Superalloys Welding materials (structural and hardf acing) Other alloys Miscellaneous Total 1 Chromium content 1983 Carbon steel Stainless and heat-resisting steel.. Full-alloy steel High-strength low-alloy and electric steel Tool steel Cast iron Superalloys Welding materials (structural and hardf acing) Other alloys Miscellaneous Total' Chromium content 8 287 71 7 4 10 7 2 2 2 400 238 6 181 37 5 2 7 6 1 1 1 247 147 7 305 33 5 4 6 7 1 2 1 371 219 1 14 4 2 ( 2 ) ( 2 ) W ( 2 ) ( 2 ) 22 1 10 3 2 ( 2 ) ( 2 ) ( 2 ) W ( 2 ) ( 2 ) 15 5 ( 2 ) 12 2 2 W ( 2 ) W w ( 2 ) ( 2 ) 16 6 ( 2 ) ( 2 ) 3 3 1 2 ( 2 ) 2 ( 2 ) 11 7 ( 2 ) ( 2 ) 1 1 ( 2 ) 2 ( 2 ) 1 ( 2 ) ( 2 ) ( 2 ) ( 2 ) ( 2 ) ( 2 ) 3 ( 2 ) 1 ( 2 ) 9 302 79 12 5 11 9 2 4 3 434 253 6 191 41 8 2 7 268 157 8 318 34 7 4 6 10 1 3 2 392 229 W Withheld to avoid disclosing company proprietary data; Miscellaneous . Data may not add to totals shown because of independent rounding, 2 Less than 1/2 unit. included with 20 TABLE 6. - Domestic production and imports of chromium ferroalloys and chromite (Thousand short tons) Chromium ferroalloys ] Chromite: Imports Year Domestic production Imports Gross weight Cr 2 3 content Chromium Gross weight Chromium content Gross weight Chromium content content 1963 300 418 226 119 36 180 260 127 69 19 30 180 443 150 285 21 113 255 89 167 1,391 931 898 507 190 605 412 368 209 86 414 1973 282 1981 252 1982 143 59 Includes high- and low-carbon ferrochromium, chromium metal. f errochromium-silicon, and Calculated apparent consumption of chromium in all forms was 329,000 st in 1983. This represented only a slight in- crease over the 1982 total, which was the lowest amount since the 1950' s, basically reflecting the recent performance of the steel industry. Chromium demand attained its highest level in 1974 at 625,000 st. In 1983 prices for chromite (f.o.b.) were $48/mt to $52/mt from the Republic of South Africa and $110/mt from Turkey; the price of imported 50- to 55-pct high- carbon ferrochromium ranged from $0,355/ lb to $0.40/lb. Total domestic chromium demand is forecast to grow at an average annual rate of 2.2 pet from 1981 to 2000. Table 7 contains world production and reserves of chromite, and chromium im- ports by the United States, as ore and f er rochromium . USES AND DEMAND ALTERNATIVES Metallurgical Prior to identifying the specific sub- stitution and surface modification meth- ods that can save chromium, the conserva- tion role of modern steel-making process technologies and novel metallurgical techniques also should be examined ( 18 , 25-2£, 37-40). Although continuous casting is well established, opportunities exist for fur- ther application. The process results in significantly higher product yields, improved product quality, and cost advan- tages over ingot casting. Use of contin- uous casting in conjunction with the argon-oxygen decarburization (AOD) pro- cess has been credited with improving chromium yield in stainless steels by 10 to 15 pet. AOD uses the furnace for melting only — a separate vessel accommo- dates decarburization and refining. Oxy- gen and argon are introduced to oxidize and remove carbon, thus achieving low carbon content while minimizing the oxi- dation of chromium and other elements and subsequent loss to slag. This greatly reduces the need for additions of low- carbon ferrochromium to obtain the de- sired composition, permits the use of cheaper raw materials (high-carbon ferro- chromium, more scrap), and results in lower costs for energy (because of re- duced operating temperatures). Wider application of duplex refining systems, some utilizing special melting and remelting techniques , appears to be a promising means of achieving substan- tial conservation of chromium. Cost- competitive steels that possess proper- ties comparable or superior to those of traditional steels can be produced with- out using large amounts of alloying ele- ments or elaborate heat treatment. This requires an understanding of the specific influence of the various fabrication- process variables on steel microstructure and the resultant properties that can be predicted. 21 TABLE 7. - World chromite mine production, reserves, and U.S. imports (Thousand short tons) Country Mine output 1981 1982 p I 1983 e Reserves Chromite 2 U.S. impo r t s 1981 1982 1983 Ferrochromium 5 1981 1982 1983 Albania Belgium Brazil Canada China Cuba Cyprus Finland France Germany, Federal Republic of ... . Greece India Iran Italy Japan Korea , Republic of ... . Madagascar New Caledonia. . . New Guinea Norway Pakistan Philippines South Africa, Republic of ... . Spain Sudan Sweden : Turkey ' L/»o«_/«r\» • ■ • • • • •• United Kingdom.. Vietnam Yugoslavia Zimbabwe Total 937 260 23 11 454 47 369 35 12 110 4 1 484 3,164 29 466 2,646 17 ( 4 ) 591 965 304 30 11 380 46 374 45 12 100 55 1 391 2,385 28 448 2,701 18 476 990 310 35 11 375 45 400 55 9 100 100 1 365 2,460 30 440 2,700 20 475 2,000 9,000 NA 1,000 19,000 NA 15,000 4,000 NA NA 2,000 1,000 23,000 910,000 NA 5,000 17,000 NA NA 19,000 14 78 18 ( 4 ) 145 482 49 111 4 45 41 3 70 277 32 34 6 6 21 13 144 ( 4 ) ( 4 ) 21 3 2 5 1 1 2 2 261 1 11 8 47 62 9,660 8,770 8,921 '1,000,000 898 507 190 428 e Estimated. Preliminary. NA Not available. Shipping-grade ore (deposit quant high-chromium and high-iron chromite; ^Average Cr 2 3 content: 1981 — 41.0 3 Average chromium content: 1981 — 5 4 Less than 1/2 unit. ^Rounded. 17 ( 4 ) 6 4 ( 4 ) ( 4 ) ( 4 ) ( 4 ) 55 4 6 ( 4 ) 16 33 141 4 4 ) 8 4 ) ( 4 ) 2 ( 4 ) 1 1 152 ( 4 ) 11 15 ( 4 ) 33 53 280 ity and grade normalized to 45 pet Cr203 for 35 pet Cr 2 03 for high-alumina chromite). pet, 1982—41. 2 pet, 1983—45. 3 pet. 7.8 pet, 1982—60.0 pet, 1983—58.2 pet. 22 Powder metallurgy also offers possibil- ities for chromium conservation. The use of powder formed by rapid solidification enables production of alloys with unique microstructures , and therefore, with properties not attainable with conven- tional metallurgical techniques. Near- net-shape technology minimizes material and energy use through reduced scrap generation. Stainless Steels (J_8, 25-26, 37-40) The largest use for chromium is the production of stainless and heat-resist- ing steels. Stainless steels actually are defined by their chromium content. Austenitic stainless steels constitute about 70 pet of U.S. stainless steel pro- duction, generally contain 17 to 36 pet Cr , and are used for many industrial pro- cessing, energy generation, pollution control, cryogenic, marine, transporta- tion, construction, and consumer product applications; martensitic stainless steels account for about 25 pet of domes- tic production, usually contain 11.5 to 18 pet Cr , and are used as a lower cost alternative to austenitic types in surgi- cal instruments and some intermediate- temperature and oil industry applica- tions; ferritic stainless steels average slightly higher chromium contents than martensitic types, but are used mostly for decorative purposes. Heat-resisting steels usually are included with stain- less steels although they contain only 4 to 10 pet Cr; they can be substituted for stainless steels in certain instances. Chromium provides passivation in iron- base alloys, and a minimum of about 12 pet Cr is required for this purpose. Additional chromium increases the resist- ance of iron-base alloys to corrosion and oxidation by various degrees. Another function of chromium in austenitic stain- less steels is to stabilize the struc- ture. Because chromium has been a read- ily available, low-cost element, and because some higher chromium steels offer outstanding fabricating characteristics, stainless steels have been designed into a large number of applications. Chro- mium savings could be accomplished by partially replacing the chromium in ex- cess of 12 pet with other alloying ele- ments, by completely replacing stainless steel with a different material contain- ing little or no chromium, by employing thinner gauge or longer lasting high- chromium alloys, or by using surface mod- ification techniques, so that the prop- erties of chromium are utilized only where they are needed. Nevertheless, changes require careful evaluation of the service requirements for the particular application. Steels possessing lower chromium con- tent provide the least chromium savings, but their mechanical and fabricating characteristics can more closely approxi- mate those of the standard stainless steels. The loss in corrosion and oxida- tion resistance caused by the lower chro- mium content can be partly or completely compensated for by the addition of other alloying elements: 1. For most applications 12 pet Cr will provide corrosion resistance. The function of chromium as an austenite sta- bilizer can be performed as effectively by manganese or nickel. In many chemical processes, however, the use of 12 pet Cr requires additions of molybdenum, sili- con, or aluminum to attain the corrosion resistance of type 304 stainless steel (the most widely used grade) . 2. Austenitic stainless steels with about 14 pet Cr appear to have adequate strength and oxidation resistance for service up to 1,400° F. 3. A composition of 12 pet Cr with silicon, aluminum, and nickel additions has corrosion resistance in aqueous envi- ronment and oxidation resistance in air superior to those of type 304 stainless steel. 4. A 9Cr-lMo steel, modified by small additions of columbium and vanadium, is being tested as a replacement for 18-pct- Cr steels in steam powerplant heat ex- changers. A 9Cr austenitic stainless steel with molybdenum and possibly copper and vanadium, having corrosion resistance comparable to that of standard grades except in severe environments, appears feasible. 23 5. Modified 6-pct-Cr steels appear to be promising replacements for the 12-pct- Cr type in automotive emission control systems . 6. High-strength duplex stainless steels and corrosion-resistant superfer- ritic stainless steels contain as much or more chromium than standard types, but afford reduced cross-section dimensions and less frequent replacement of components. Several no-chromium alternatives are in use or under development: 1. Iron-manganese-alurainum alloys are being developed as potential substitutes for austenitic stainless steel grades in heat-resistant applications at moderate temperatures and some corrosion-resistant applications. Although brittle, they have been successfully used in furnace and ocean environments. 2. Aluminum steels such as Fe-8Al-6Mo have demonstrated high-temperature oxida- tion resistance in air superior to that of type 304 stainless. 3. High-silicon (9 to 18 pet) alloys of iron, cobalt, or nickel offer excel- lent resistance to corrosion but need im- provement with regard to mechanical prop- erties and fabrication. Smaller (1 to 4 pet) additions of silicon are sufficient to enhance oxidation resistance. 4. Silicon-molybdenum ductile iron has performed more effectively than high- chromium steels in high-temperature cor- rosive and/or erosive environments such as furnace grates and auto exhaust mani- folds. This material is a possible al- ternative to high-chromium steels in nu- merous high-temperature applications. 5. Nickel-copper and nickel-molybdenum alloys may also be used for corrosion re- sistance with some sacrifice of perform- ance and mechanical properties. 6. Metals such as titanium (seawater exposure, chemical apparatus), tantalum (chemical apparatus), aluminum, nickel, platinum, zinc, and zirconium, and non- metallic materials such as glass (excel- lent resistance to corrosive chemicals) , graphite (high strength), ceramics, and plastics have proven records in a num- ber of specialized functional and decora- tive applications. In most cases larger scale use is limited mainly by costs, availability, and complexities concern- ing fabrication and installation, but in- creased use of plastics appears to be a viable alternative to stainless steel, particularly where elevated-temperature service is not a factor. Plastics such as polyethylene, Teflon, and polyurethane have excellent resistance to corrosive chemicals and are readily fabricated into plant equipment. Glass mat or fiber re- inforcement provides some strength and extends applicability. Surface protection via cladding and coating techniques is an additional op- tion that can be used to prevent corro- sion, oxidation, and wear. This approach also offers the opportunity for consider- able reductions in the use of chromium- containing stainless steels: 1. Cladding technology is well estab- lished. Individual strips of metal are passed through a pressure rolling mill to merge the lattices of the metals into a common structure; subsequent thermal treatment promotes diffusion, improves bond strength, and provides cold-work stress relief. Most active metals and alloys can be clad. Stainless-clad car- bon steels are used extensively in the chemical process industries for large columns and vessels. The initial cost is lower than for solid stainless, but usage is limited to configurations that can be made from sheet and plate, specialized joining techniques must be employed, and edges must be protected. Additional us- age is technically feasible but uneco- nomic at present. Cladding base steels with metals other than stainless steel could achieve even greater chromium savings . 2. In contrast to wrought metal clad- ding, electroplating can be employed to obtain a chromium coating. Fabricated parts, brittle materials, and selected areas can be electroplated, but the majoc limitation is the size and shape of a component that can be plated. Chromium- rich diffusion coatings have been shown to be more widely applicable than electroplating, but item size and shape limitations also exist, as well as the requirement for high-temperature processing. 24 3. Directed energy beam techniques (ion beam processing, laser beam process- ing) can produce chromium-containing coatings which are metallurgically bonded to the surface with performance compar- able to or better than that of bulk chro- mium alloys. Since a vacuum or helium atmosphere is required, the substrate is limited in terms of size, and it must also be open and recess-free. 4. The oxygen-diffused nitriding pro- cess (salt bath treating) has the capa- bility of producing a surface comparable or superior to that with chromium plating with respect to corrosion and wear re- sistance in many applications at similar cost. In addition, the discharge of none of the compounds present in the system effluent is restricted. 5. Electroless nickel is an amorphous nickel and phosphorus coating applied via autocatalytic chemical reduction. It of- fers high strength, excellent abrasion, wear, and corrosion resistance (in most environments the corrosion resistance of hard chromium is much less) , uniform thickness, solderability , and ease of ap- plication. The petroleum and chemical process industries are the principal users of electroless nickel coatings. 6. Some corrosion-resistant materials, such as elastomers and lead, are lim- ited to specialized lining applications. Their lack of strength must be compen- sated for by the structural capabilities of the basis material. Polymer concrete (concrete in which aggregate is bound in a dense matrix wifh a polymer binder) has demonstrated its utility as a liner for carbon steel exposed to corrosive geo- thermal brines, which chemically attack most conventional construction materials. Polymer concrete also offers a 10- to 20- pct cost reduction. Changes to less exotic chemical-process equipment can be made in some circum- stances through modifications to process chemistry by using inhibitors, making minor changes in the process stream, and eliminating contaminants. Stainless steel scrap is the major source of secondary chromium supply. Home scrap generated in the production process is retained and reused. Prompt industrial scrap can also be recycled ef- fectively if properly segregated, partic- ularly the stainless steels containing other high-value alloy metals. An opera- tion in Pennsylvania even recovers chro- mium and nickel in the form of remelt al- loy from plant particulate wastes, such as dusts, mill scale, and grinding swarf. Although there is considerable chromium in the waste products of some other met- allurgical industry processes, collection and processing costs hinder economical recovery on a large scale (except for su- peralloys) . The Bureau of Mines is ac- tively developing recycling technology in these areas (41) . Much obsolete stain- less steel scrap is downgraded or not recovered. Scrapped automobiles, partic- ularly the catalytic converter canister, represent a large source of available chromium. Alloy Steels U8, 25-26, 37-40) After stainless steels, the next largest metallurgical consumer of chro- mium is alloy steels, which owe their enhanced properties to a specified alloy content, often some combination of chro- mium, molybdenum, and/or nickel. Chro- mium influences hardenability — the prop- erty of a steel that determines the depth and distribution of hardness that may be induced by quenching — and can be present up to 1.7 pet. Alloy steels are used in structural engineering, machinery, and transportation equipment. Common AISI grades of these steels are the chromium- molybdenum 4100 series such as 4130 and 4140, containing 0.8 to 1.1 pet Cr and used for fittings, valves, bolts, shafts, teeth, etc.; the nickel-chromium-molyb- denum 8600 and 8700 series such as 8620 with 0.4 to 0.6 pet Cr, for use in gears; and the straight chromium 5100 series such as 5160 containing 0.7 to 0.9 pet Cr, used in coil and leaf springs. Historically, the basis for alternative alloy steels has been that of achieving equivalent hardenability as exemplified by the development of the National Emer- gency Steels during World War II, and the SAE EX steels during the Canadian mining strike and subsequent nickel shortage in 25 1969-70. In the last several years com- puterized hardenability prediction sys- tems have provided a rapid and highly accurate means of predicting the proper- ties of a steel as a function of composi- tion, thus offering the opportunity to design substitute alloys in less time by avoiding a lengthy program of melting and evaluating experimental compositions. (Two chromium-free steels, a manganese- molybdenum grade and a manganese-nickel- molybdenum grade, have been computer- designed under Bureau of Mines contract to be equivalent to the AISI 8600 and 4100 steels.) While the use of chromium is highly efficient, many opportunities exist to eliminate or reduce the chromium content of these steels by using other alloying elements that also have a strong influence on hardenability, although in most areas the addition of these substi- tute elements carries an economic penalty relative to current chromium prices. The most commonly used carburizing steels contain 0.5 to 1 pet Cr for case and core hardenability, but several stan- dard chromium-free alternatives are available, usually with increased amounts of manganese and/or molybdenum. Through-hardening grades normally con- tain 0.5 to 1.5 pet Cr for hardenability and toughness, but manganese, molybdenum, boron, and silicon levels can be adjusted to produce chromium-free substitutes. Constructional alloy plate steels, used for bridges and other structures, have adequate chromium-free alternatives available, usually with higher molybdenum and boron content. Abrasion-resistant plate steels also have varieties without chromium, such as carbon-manganese , carbon-manganese-molyb- denum-boron, and carbon-manganese-molyb- denum-nickel-boron quenched and tempered alloys . Weathering plate steels, used in welded bridges and in buildings where weight savings and durability are required, usu- ally contain chromium, but some chromium- free types are available with increased nickel and copper levels. Low-alloy constructional cast steels have an average chromium content of 0.7 pet, which can be adequately substituted for by increasing the levels of one or more other alloying elements such as man- ganese, nickel, molybdenum, or boron. Spring steels (0.7 to 0.9 pet Cr) and grinding mill ball steels (0.45 pet Cr) have chromium-free alternatives available. An alternative bearing steel with 0.4 to 0.6 pet Cr offers superior processing and performance characteristics at lower cost compared with high-carbon grades containing 1.3 to 1.6 pet Cr. Ultra-high-strength steels are used principally in load-bearing aircraft forging applications that require high strength and good fatigue resistance. These steels all contain chromium (0.8 to 1 pet) , and no known chromium-free sub- stitute alloys are available. Likewise, no substitutes are available for existing pressure vessel plate steels (0.5 to 2 pet Cr to provide corrosion resistance) . Many different heat treatments are used to enhance the engineering properties of steel. Induction heating provides high energy density for controlled depth heat- ing, reducing the amount of heat that must be removed in the quenching pro- cess. Selective use can reduce or elimi- nate the need for hardenability-enhancing alloys in heat treating engineering steels. Applications other than harden- ing, such as induction treatment to pro- vide corrosion resistance, have been dem- onstrated experimentally. High-strength low-alloy (HSLA) steels generally do not contain chromium. Their scope could be extended to include areas reserved for heat-treatable chromium- containing steels. High-Strength Low-Alloy Steels 08-39, _42-_43) High-strength low-alloy (HSLA) steels constitute a separate class of steels with high yield strength and good tough- ness, forraability, and weldability. These properties are achieved by using micro additions (less than 0.1 pet) of key alloying elements (most commonly co- lumbium, vanadium, and titanium) and con- trolled thermomechanical treatments. In some cases, other alloying elements, such 26 as molybdenum, nickel, and chromium, are also added, but the majority of HSLA steels do not contain chromium. Conventional low-alloy steels, contain- ing varying amounts of molybdenum, nick- el, and chromium, can attain equivalent or greater yield strengths, but they re- quire heat treatment and their higher carbon contents adversely affect tough- ness and weldability. Since HSLA steels achieve their strength without an in- crease (and usually with a substantial decrease) in carbon content, properties other than strength are preserved. HSLA steels have been used predominant- ly to meet a combination of requirements in pipeline service and for fuel-saving weight reductions in the automotive in- dustry. HSLA steels are becoming avail- able in an increasing number of forms for a variety of applications , including pos- sible displacement of chromium-containing heat treatable steels. Tool Steels ( 18 , 25, 37) The chromium content of tool steels ranges from 0.25 to 12.5 pet, but most contain 3 to 5 pet Cr. However, the total amount of chromium used in tool steels is small. The major use is in high-speed steels (cutting tools, hot- work dies) , in which chromium plays an important role in the hardening mecha- nism. In the high-carbon, high-chromium, cold-work steels (blanking, forming, drawing, and slitting tools) , chromium is essential for hardness and wear resist- ance. Sintered carbides perform ade- quately as substitutes in most cases (78 pet) for these two types, but serious cost penalties are incurred. Replacement of chromium hot-work steels (dies forg- ing, molding, and extrusion tooling) is not feasible, and present technology does not indicate the development of chromium- free substitutes. Some of the other tool steels can be replaced by lower chromium steels or chromium-free materials, but the quantity of chromium involved is negligible. Alloy Cast Irons Q8, 37 ) Indefinite chill rolls with chromium contents of 1.5 to 2 pet are interchange- able with cast steel rolls with less than 1 pet Cr or with spheroidal graphite rolls containing 0.4 pet Mo and no chro- mium. However, if these substitutions were made, roll performance in the mills would probably be reduced. Alternatives to abrasion-resistant cast irons, containing 15 to 28 pet Cr for abrasion and impact resistance, include NiHard type 2 (1.5 to 2 pet Cr) , NiHard type 4 (6 to 8 pet Cr) , wrought low-alloy steels, and chromium-molybdenum pearlitic or oil-quenched and tempered steels con- taining less than 2 pet Cr. Alloy combi- nations of manganese, boron, tellurium, molybdenum, and tungsten could also be considered as chromium replacements. Engineering castings contain 0.5 to 2 pet Cr for wear resistance, strength, and dimensional stability in transportation applications. The trend in smaller sec- tion sizes is toward irons with less or no chromium, such as tin-molybdenum and copper-molybdenum irons. Superalloys (J_8, 25-26, 37, 39 ) Typically, wrought nickel-base and iron-nickel-base superalloys contain 15 to 20 pet Cr; cast nickel-base, 10 to 15 pet; and cobalt-base, 20 to 30 pet. The presence of chromium is essential in su- peralloys to provide the resistance to oxidation and hot corrosion required for gas turbine engines. However, the high chromium content is needed only at the surface, not for the mechanical proper- ties of the material. Ion implantation and laser annealing show the most promise to achieve the surface requirement for chromium while eliminating it from the bulk of the alloy. Scrap recycling technology is pursued in the superalloy field because of the relatively high value of these materials (44). 27 Other Alloys (1_8, 37_) In alloys of aluminum, titanium, and copper, chromium is used primarily to control microstructure and improve phys- ical and mechanical properties, but sub- stitutes for chromium are readily available. Aluminum-Base Alloys Chromium is used as a minor alloying addition in many of these high-perform- ance wrought alloys which are used in a variety of aerospace, marine, and surface vehicle load-bearing applications. The chromium alloying additions control re- crystallization behavior, help achieve consistent product performance, and im- prove resistance to stress corrosion cracking. Zirconium and manganese pro- duce effects that are similar to those produced by chromium, and replacement of the alloys containing chromium with chromium-free grades is possible in many applications. However, the slight per- formance penalties involved could be im- portant in some critical structural uses. Also of concern are the lead time and expense involved in qualifying materials for aerospace applications. Titanium-Base Alloys Chromium is used as an alloying addi- tion (2 to 11 pet) in several commercial- ly available titanium alloys. Chromium serves to stabilize the high-temperature beta allotrope of titanium. Other ele- ments (molybdenum, vanadium) also pro- duce similar effects and are frequent- ly used instead of or in combination with chromium. Therefore, chromium-free alloys are available with similar characteristics. Copper-Base Alloys Chromium additions (about 1 pet) pro- duce useful strengthening effects in copper alloys but do not exhibit partic- ularly unique property combinations. Apparently chromium-free grades could be substituted without significant cost or performance penalties. Refractory (1_8, 37"29, 45-46) — Chromite Refractories Chromite in the mineral (spinel) form imparts thermal shock and slag resist- ance, volume stability, and structural strength in refractories that range from all chromite to various mixtures of chro- mite and magnesia. They are designated as chrome (essentially all chromite) , chrome magnesite (chromite equal to or greater than the weight percent of magne- site) , and magnesite chrome (greater than 50 wt pet magnesite). Refractories are supplied as granular material or shaped brick. The two major uses of chromite in granular form are as maintenance gunning mixtures for steelmaking furnaces and as facing sands in steel foundries. Substi- tute gunning materials include magnesite, dolomite, salvaged and reprocessed chro- mite, and chromium-free basic materials. Substitute materials for facing sands in- clude zircon, olivine, and silicon sands. Olivine is preferred for high-manganese steel castings. Silica sands are primar- ily used as backup, not facing, sands. The brick may be bonded chemically (un- burned) , burned, or fusion cast. The steel industry is the predominant consumer of chrome-bearing refractories. However, chrome ore usage appears signif- icantly less critical now than just a few years ago. The consumption of these re- fractories has been on a downward trend because of the continuing decline in open-hearth furnace steelmaking, which has been the principal user of chromite (table 8). The main replacement for the open-hearth process — the basic oxygen converter — uses refractories based only on periclase (MgO) with carbon. The other alternative, the electric furnace, does utilize chromite, but in the past 28 TABLE 8. - Steel production in the United States, by type of furnace (Percent) Year Open Basic oxygen Electric hearth converter '1963 81 8 10 1973 26 55 18 1981 11 61 28 1982 8 61 31 1983 7 62 31 Bessemer furnace production: 1 pet. several years the extensive application of water-cooled sidewall panels and roofs has reduced the need for chromite by 60 to 70 pet. Most electric furnaces use brick made of periclase with carbon or graphite in the bottom, slag line, and interval from the slag line to the lower edge of the water-cooled panels. It is estimated that about 60 pet of installed electric furnace capacity in the United States is now water cooled, a practice that should steadily increase. Argon- oxygen decarburization and vacuum oxygen decarburization employ periclase-chrome or dolomite refractories. Apparently do- lomite is capable of totally replacing periclase-chrome in this application. Increased demand for higher quality steels has led to changes in ladle metal- lurgy and increased use of degassers and related processes, with a resulting pref- erence for chrome refractory usage. La- dles are increasingly lined with peri- clase-chrome or other materials rather than fireclay, and degassers are conven- tionally lined with periclase-chrome and alumina refractories. Glass, nonferrous, and rotary kilns also utilize chromite. For copper con- verters, higher chromium compositions re- portedly give better performance. In most other applications, substitution of magnesite chrome for chrome and chrome magnesite can be made at no penalty in performance and minimal increase in ini- tial cost. The extent of such substitu- tion could yield a savings in chromite consumption for brick well in excess of 50 pet. Considerable potential exists for sal- vage and reuse of chromium-bearing brick in all consuming industries (18, 47-49). Chromium-bearing bricks in many units are distinctly different and recognizable from chromium-free refractories even af- ter use, so the bricks can be separated by hand and stacked separately for sal- vage, reprocessing, and reuse. Up to 33 pet of the bricks in an original steel- producing structure can be salvaged by such practice. Chemicals (18, 37 ) Chemical-grade chromite ore is roasted with soda ash and lime to convert the Cr 2 3 to Na 2 Cr0 4 . This is leached with water to extract the soluble sodium chro- mate. Sodium chromate is acidified with sulfuric acid or carbon dioxide to pro- duce the principal chromium chemical, sodium di chromate. Most chromium chemi- cals are made from sodium dichromate. In 1982, the Environmental Protection Agency set out its final regulations in accordance with the Clean Water Act on pollutants discharged in wastewater from inorganic chemical plants. Included in regulation coverage are chrome pigments and sodium dichromate. The Bureau of Mines is developing process technologies for reducing chromium losses in certain chemical operations (50). Pigments and Paints The main chrome pigments are chrome yellow, molybdenum orange, zinc chromate, chrome green, and chrome oxide green. The primary uses for chrome pigments are for coloring plastics, for printing inks, and in paints for highway lines and in- dustrial finishes (vehicles, equipment, appliances) . Zinc chromate is used main- ly as a corrosion inhibitor primer for metals. Replacement of chromium pigments with proven nonchromium pigments to ob- tain the same color would involve a sub- stantial price penalty. The chrome pig- ments could be replaced by pigments such as carbon black, iron oxide, and titanium 29 oxide, but these substitutes would limit the number of colors. Leather Tanning Chromium compounds are used to tan the bulk, of the leather produced in the United States. Substitutes such as vege- table tanning compounds exact definite price and performance penalties. Metal Finishing and Treatment Chromium is used for chromium plating (decorative and engineering) and the treatment of copper, brass, zinc, and cadmium alloys, and galvanized steel. About 60 pet of the chromium consumed in electroplating is used in decorative end uses, 30 pet is used in engineering (hard) chromium plating, and the rest in other forms of metal finishing (chroraate conversion coatings, chromic acid anodiz- ing of aluminum). Obviously, decorative chromium plating could be discontinued — materials now being plated could be painted or made from chromium-free mate- rials such as plastics. Hard chromium plating is used for its excellent physi- cal properties, hardness, wear resist- ance, and low coefficient of friction. The only apparent substitute is electro- less nickel, which is better than hard chromium for wear resistance in certain applications. In addition, its "throwing power" is far superior, and it does not degrade the fatigue properties as hard chromium plating sometimes does. Another use for chromium plating is in the manu- facture of "tin-free steel" that can re- place tinplate in some canning uses. Only 15 to 20 pet of the chromic acid used actually ends up on the plate, and a considerable saving of chromium can be accomplished by recycling the wasted material. Plating baths using triva- lent chromium compounds in place of chro- mic acid would also yield savings from the use of less chromic acid spray and effluent. Drilling Mud Additives Sodium dichromate is used to produce chromium lignosulf onates for drilling muds; no satisfactory substitutes exist, especially for drilling deep wells (over 10,000 ft). Chromium compounds also are used as a corrosion inhibitor in addi- tives to drilling muds to greatly extend the life of the drilling equipment. Water Treatment Compounds Sodium dichromate is used to make water treatment compounds such as corrosion in- hibitors for cooling towers and atr con- ditioners. The largest users are petro- chemical and chemical plants and oil refineries. No substitutes have been satisfactory as corrosion inhibitors at temperatures of 150° F or higher, such as are found in petrochemical and oil refin- ery operations. Substitutes are avail- able for less critical applications, such as air conditioners and cooling towers operating at 120° F or less, but they re- sult in a performance and price penalty. Wood Treatment Compounds Sodium dichromate is used to make copper-chromium-arsenic compounds to pro- tect wood against termites, fungus, etc. Other preservatives such as creosote and pentachlorophenol can be used to treat wood but in some cases would result in a performance penalty, primarily in paintability . Chemical Manufacture and Other Uses Sodium dichromate is used to manufac- ture other chemicals such as potassium dichromate, chromium organic complexes for treating textiles and paper, chromium dioxide for magnetic tapes, and chromium- containing catalysts for the synthesis of ammonia and methanol and for many hy- drogenation and polymerization reac- tions. In most cases no substitute is 30 known for these specific chromium uses, and the elimination of chromium would re- sult in a performance penalty in practi- cally all cases. SUPPLY ALTERNATIVES Domestic (18, 51-52) The Bureau of Mines assessed the via- bility of 34 nonlaterite and 9 nickelif- erous laterite deposits of chromite in the United States. Although some of these deposits have been in production in the past, none of them was considered suitable for development with existing technology at current market prices — domestic production of metallurgical- and chemical-grade chromite would require chromite market prices of about twice those prevailing in January 1981. The minimum lead time required to bring the various operations on-stream ranges from 1 to 4 yr, and, based on domestic re- source estimates, production would be relatively small and of short duration. Most of the U.S. chromium resources occur in the Stillwater Complex in Montana as stratiform deposits, in northern Califor- nia as podiform deposits, and in the Ore- gon Beach Sands as placer deposits. Foreign (J_8, 39, 45, 52-54) Although world chromite reserves are substantial, they are highly concentrated in southern Africa — over 90 pet are held by the Republic of South Africa and Zim- babwe. Only a few countries, nearly all of which are in the eastern hemisphere, produce significant amounts of chromite (table 7), and of those, the U.S.S.R. and the Republic of South Africa are by far the leading producers, together approach- ing 60 pet of the total. From another perspective, centrally planned economy countries (essentially the U.S.S.R. and Albania) account for about 40 pet of world production. Present sources that appear capable of continuing as large producers of chromite well into the next century include the Republic of South Africa, Zimbabwe, the U.S.S.R., India, and Finland ( 54 ) . Announcements by sev- eral other countries of new chromite discoveries and projects to expand exist- ing capacity have increased the likeli- hood of modest decentralization of supply over the next decade or two. However, the vast chromite resources of southern Africa should ensure eventual concentra- tion of production in that region. The widespread adoption of argon-oxy- gen-decarburization (AOD) process steel- making opened the high-iron-content chro- mite of the Republic of South Africa to metallurgical use (and effectively blurred the traditional distinction among metallurgical-, refractory-, and chem- ical-grade ores) . Whereas f errochromium production had long been restricted to metallurgical-grade ore with its high chromium-to-iron ratio, AOD permits the utilization of high-carbon ferrochromiura (made from high-iron chemical-grade chro- mite) rather than the costlier low-carbon ferrochromiura. Conversion of chromite to f errochromium is being accomplished increasingly in the ore-producing countries, as is the con- struction and planning of new ferrochro- raium capacity, to accommodate both cap- tive needs and export markets. This is occurring at the expense of some of the traditional ferrochromium producers (who are also the principal consumers) — the United States, Western Europe, and Japan. The top chromite producers, the U.S.S.R. and the Republic of South Africa, are also the world's largest producers of ferrochromium, nearing half of the total, followed by Japan and Sweden. Not sur- prisingly, Zimbabwe also has established itself as a major ferrochromiura supplier. It is probable that world ferrochromium production capacity also will predominate in southern Africa in the long term. Stockpile (52) Inventories of metallurgical-, chem- ical-, and refractory-grade chromite ore are all well below National Defense Stockpile goals. However, an inventory of chromium ferroalloys in excess of the goal is held for offset against chro- mite. It was announced in December 1982 that the General Services Administration (GSA) would begin a program of upgrading stockpiled chromite into high-carbon 31 f errochromium , and in June 1983 GSA so- licited bids to convert 125,000 st of stockpiled chromite into f errochromium. A panel of industry experts assembled by the American Society for Metals at the request of the U.S. Department of Com- merce conducted a quality assessment of the 7.5 million lb of chromium metal in the National Defense Stockpile. The pan- el concluded that the chromium metal held in the stockpile is not suitable for pro- ducing vacuum-melted superalloys for air- craft jet engines or other alloys which have stringent purity requirements for chromium metal as an alloying element. The panel also noted that the stockpile contains no high-purity f errochromium usable for aircraft superalloys (55) . SUMMARY OF DEMAND AND SUPPLY ALTERNATIVES Current U.S. chromium consumption could be reduced by approximately one-third by using available technology to substi- tute alternative materials and processes, to recover and recycle waste chromi- um, and to design for greater chromium efficiency . Chromium is essential for corrosion and oxidation resistance in stainless steels, but chromium savings can be accomplished in various stainless steel applications by partially replacing the chromium in excess of 12 pet with other alloying ele- ments, by completely replacing stainless steel with a different metallic or non- metallic material, by employing thinner gauge or longer lasting high-chromium al- loys, or by using surface modification techniques such as cladding, plating, and coating. Stainless steel scrap is the major source of secondary chromium supply. Al- though there is considerable chromium in the waste products of some other metal- lurgical industry processes, collection and processing costs hinder economical recovery on a large scale. The chromium content of alloy steels can be eliminated or reduced by using other alloying elements that also have a strong influence on hardenability . How- ever, no substitutes are available for existing ultra-high-strength or pressure vessel plate steels. Chromium plays an important role in the hardness and wear resistance of tool steels. Substitution with sintered car- bides entails serious cost penalties. Low- or no-chromium alternatives are available for roll, abrasion-resistant, and engineering alloy cast irons. The presence of chromium in superalloys markedly improves resistance to oxidation and hot corrosion. However, the high chromium content is essential only at the surface, not for the mechanical proper- ties of the material. In alloys of aluminum, titanium, and copper, chromium is used primarily to control microstructure and improve prop- erties, but substitutes for chromium are readily available. Continuous casting results in signifi- cantly higher product yields. Its use in conjunction with the AOD process has been credited with improving chromium yield in stainless steels by 10 to 15 pet. Wider application of duplex refining systems for steel production appears to be a promising process area for achieving substantial conservation of chromium. Powder metallurgy techniques as rapid solidification and near-net-shape offer possibilities for chromium conservation by producing unique properties via alloy microstructure and by generating less scrap. The importance of chrome-bearing re- fractories has diminished because of the continuing decline in open-hearth furnace steelmaking. Replacement of chromium pigments with proven alternatives would incur a sub- stantial cost penalty or limit the number of available colors. No practical substitutes exist for the chromium compounds that are used to tan the bulk of leather produced in the United States. The chromium used for decorative elec- troplating could be replaced by chromium- free materials such as plastics, or by painting the substrate. Electroless nickel provides an alternative to hard chromium plating. 32 No satisfactory substitutes exist for chromium compounds used in deep-well drilling muds. No chromium-free substitutes have been proven satisfactory as corrosion in- hibitors at temperatures of 150° F or higher such as are found in petrochemical and oil refining operations. Alterna- tives are available for less critical applications. Nonchromium wood preservatives are readily available, but do not offer com- parable paintability. Although some domestic chromite depos- its have been in production in the past, none is considered suitable for develop- ment with existing technology at current market prices. The known chromite resources of the Re- public of South Africa and Zimbabwe are so vast that eventual concentration of supply there is expected. With the trend toward conversion of chromite to f errochromium in the ore- producing countries, it is probable that future world ferrochromium produc- tion will also become highly concentrated in the Republic of South Africa and Zimbabwe . MANGANESE BACKGROUND The importance of manganese arises mainly from its desulf urizing, deoxi- dizing, and alloying functions in iron- making and steelmaking, which account for about 90 pet of its use. The minor areas of manganese use are dry cell batteries and chemicals (tables 9 and 10). Manganese ore products containing 35 pet or more Mn have not been produced domestically since 1970. Some manganese is produced in the form of low-grade (10 to 14 pet) manganif erous ores, but it satisfies only a very small amount of U.S. primary demand. The principal sources of recent manganese ore imports are Gabon, the Republic of South Africa, Brazil, Australia, and Mexico. Manganese ore was the dominant form in which manga- nese was imported until 1977. Imports of TABLE 9. - Consumption of manganese ore in the United States' (Thousand short tons) Use 1981 1982 1983 Manganese alloys and 745 148 184 412 84 113 274 Pig iron and steel.... Batteries, chemicals, and miscellaneous .... 106 151 1,077 609 531 Containing 35 pet or more manganese (natural) . manganese in upgraded forms, consisting for the most part of high-carbon ferro- manganese, have since been markedly greater than those of ore (table 11). The Republic of South Africa and France presently are the leading suppliers of manganese ferroalloys to the United States. (The implications for the domes- tic ferroalloy industry regarding the shift in imports from ore to processed form have been discussed previously.) At current prices there are no reserves of manganese ore in the United States con- taining 35 pet or more Mn or from which concentrates of such a grade could be commercially produced. Although technol- ogy for making ferromanganese from lower grade ores is available, the use of high- manganese content ores is far more cost effective. In 1983, the total consumption of man- ganese in the United States declined to 668,000 st, the lowest quantity since before 1960, and far below the high of 1,554,000 st in 1973. As with chromium, the recent sharp decline in manganese demand paralleled the drop in output of the steel industry. A representative average price for metallurgical ore con- taining 48 pet Mn was about $1.38 per long ton unit, c.i.f. U.S. ports in 1983, down from $1.58 in 1982. The average an- nual growth rate to the year 2000 for manganese demand in the United States is forecast at 1.6 pet (base year 1981). 33 TABLE 10. - Consumption by end use of manganese ferroalloys and metal in the United States (Thousand short tons, gross weight) End use Ferroraanganese Si licoraanganese Manganese metal 1981 Carbon steel , Stainless steel and heat-resisting steel Full-alloy steel , High-strength low-alloy steel , Electric steel , Tool steel , Cast iron , Superalloys , Other alloys , Miscellaneous and unspecified , Total 2 , 1982 Carbon steel , Stainless steel and heat-resisting steel , Full-alloy steel , High-strength low-alloy steel , Electric steel , Tool steel. , Cast iron Superalloys Other alloys , Miscellaneous and unspecified , Total 2 , 1983 Carbon steel , Stainless steel and heat-resisting steel , Full-alloy steel High-strength low-alloy steel Electric steel Tool steel Cast iron Superalloys Other alloys Miscellaneous and unspecified Total 2 621 12 105 60 C 1 ) (') 17 W 2 2 821 329 8 45 37 (') (') 13 W 2 4 439 335 15 38 37 (') (') 15 W 1 4 446 95 5 31 10 (') (') 9 W 3 2 156 67 3 18 7 (') (') 8 W 2 1 106 50 4 13 5 (') (') 8 W 1 C 1 ) 83 3 1 1 (') (') (') (') 11 1 24 2 1 1 (') (') (') (') 8 C 1 ) 17 2 1 1 (') ( ] ) (') (') 8 1 18 W Withheld to avoid disclosing company proprietary data: ous and unspecified. 'Less than 1/2 unit. included with Miscellane- Data may not add to totals shown because of independent rounding. 34 TABLE 11. - Domestic production and imports of manganese ferroalloys and manganese ore (Thousand short tons) Manganese ferroalloys ' Manganese ore: Imports Year Domestic production Imp orts Gross weight Mn Gross Mn Gross Mn content weight content e weight content 1963 e 922 695 e 173 131 2,390 1,124 893 688 438 336 1,510 722 390 292 808 615 639 301 207 163 560 430 238 111 2 86 2 70 488 364 368 178 e Estimated. includes f erroraanganese, silicomanganese, and manganese metal. 2 Ferroraanganese only; silicomanganese and manganese metal production data withheld to avoid disclosing company proprietary data. World production of manganese, world man- ganese reserves, and exports to the United States are contained in table 12. USES AND DEMAND ALTERNATIVES Metallurgical (56-63) Iron and Steel Manganese is consumed both in ironmak- ing and steelmaking (fig. 1). The use of iron ore with a low manganese content re- quires additional manganese in the blast furnace for desulf urization, usually as some combination of manganese-containing iron ore, low-grade manganese ore, high- grade manganese ore fines, recycled slag, and scrap. Some manganese loss occurs in the slag, and, to a lesser extent, in the flue dust. The optimal hot-metal manga- nese level of 0.6 to 0.8 pet provides several beneficial effects during steel- making, such as enhanced desulf urization, increased yield, longer refractory life, and reduced flux consumption. Much of the manganese in the hot metal is lost during steel production, primarily to the slag. Molten steel contains dissolved sulfur and oxygen which generally impart unde- sirable properties if retained in the solidified steel. In the steelmaking process manganese ferroalloys are added either mostly in the furnace (open hearth) or after the metal has been tapped into the ladle (basic oxygen con- verter and electric furnace) in order to perform the essential roles of taking the sulfur and oxygen into the slag or com- bining with them in a more benign form in the final product. However, aluminum and silicon are better deoxidizers, so man- ganese usually is not used alone for de- oxidation. Aside from the function of tying up impurities, manganese improves the mechanical properties of steel by Fe and Mn ores "1 Discard-^-] Casting FIGURE 1. - Flowsheet showing manganese inputs for production of steel by blast furnace- basic oxygen process. 35 TABLE 12. - World manganese mine production, reserves, and U.S. imports (Thousand short tons except as otherwise noted) Mine output Countrv Mn , pet 1981 1982 F 1983* Reserves (Mn content) U.S. imports Mn ferroalloys l .2 1981 1982 1983 Manganese ore 5,4 1981 1982 1983 Australia Bolivia Brazil Bulgaria Canada Chile China France Gabon Germany, Federal Republic of ... . Ghana Greece Hungary India Indonesia Italy Japan Korea , Republic of ... . Mexico Morocco Norway Pakistan Philippines Portugal South Africa, Republic of . . . . Spain Sudan Thailand Turkey U.S.S.R United Kingdom. . Yugoslavia Zaire Total 37-53 28-54 38-50 30- 32-35 20 + 50-53 30-50 48-50 30-33 10-54 47-56 30 24-27 27 + 50-53 35- 30 + 30-48+ 48 46-50 27-46 30-31 30 + 30-57 1,555 1 2,251 50 28 1,760 1,640 246 6 78 1,682 3 10 96 637 121 ( 6 ) 5,555 ( 6 ) 12 16 10,090 34 20 1,248 ( 6 ) 2,580 50 18 1,760 1,667 176 6 91 1,596 20 10 86 561 106 ( 6 ) 5,750 ( 6 ) 9 8 10,830 33 1,491 ( 6 ) 2,300 50 18 1,760 2,047 210 6 94 1,455 19 10 85 386 81 ( 6 ) 3,181 ( 6 ) 7 4 11,500 33 51,600 NA 20,900 NA NA 15,000 110,000 4,000 NA NA 21,500 NA NA NA 3,500 600 NA NA 407,000 NA NA NA 365,000 NA NA 6 12 62 5 189 ( ( 6 ) 46 5 33 274 10 14 14 18 44 20 104 1 10 6 40 4 20 255 17 16 16 59 3 117 6 3 42 33 28 140 6 26 NAp 25,894 26,607 24,739 1,000,000 671 555 481 66 76 180 65 25 227 639 37 6 4 46 3 9 132 238 29 79 171 64 ( 6 ) 25 368 "Estimated . Preliminary. NA Not available. NAp Not applicable. Ferromanganese and silicomanganese. tent: 1981— fer t; 1983 — ferroma ese. tent: 1981—47.1 pet; 1982—46.7 pet; 1983—48.4 pet romanganese, 77.8 pet; 1982 — ferromanganese, 77.9 nganese, 78.0 pet, silicomanganese, 65.9 pet. ''Average manganese con silicomanganese, 66.2 pc 3 35 pet or more mangan Average manganese con -Terromanganese only. 'Less than 1/2 unit. Data may not add to totals shown because of independent rounding ^Rounded. pet, 36 imparting alloying effects of increased strength, toughness, hardness, and hardenability . The bulk of manganese ferroalloys is consumed in the production of plain car- bon steel, and most of the remainder is used in the various alloy steels. With the exception of carbon, manganese is the least expensive means of adding strength to steel, and manganese even replaces carbon in high-strength low-alloy steels since high carbon content can adversely affect other properties. The manganese content of carbon and alloy steels ranges from a few tenths to less than 2 pet; stainless steels usually do not exceed 2 pet Mn, but some require much higher lev- els; and high-manganese steels, such as Hadfield steel, may contain as much as 14 pet Mn. The surface of Hadfield steel hardens under repeated impact, but its interior retains toughness and is there- fore used in railroad applications and mining and earthmoving equipment. The type of ferroalloy used to add manganese to steel is determined by cost and the technical constraints dictated by the desired products. High-carbon f erromanganese is normally used since it is considered the most economic form. Medium-carbon and low-carbon grades of f erromanganese are necessary where the carbon content of the steel is critical, but if the introduction of carbon could be detrimental, and silicon content is acceptable to the product requirements , silicomanganese is used. Silicomanganese is also less expensive than medium- or low-carbon f erromanganese, and the sili- con also acts as a deoxidant , leaving a greater amount of manganese in the steel. There is no practical substitute for manganese in steelmaking. Potential sub- stitutes for manganese as a steel desul- furizer include zirconium, titanium, and rare earth metals, and possibly calcium and magnesium, but these metals cannot be supplied in sufficient quantities at low prices. Likewise, equivalent properties can be obtained with other alloying met- als such as chromium, molybdenum, and nickel, but only at much higher cost. Past and present developments in steel- making technology have brought about manganese conservation. The phasing out of open-hearth steelmaking has resulted in a corresponding decline in unit manga- nese consumption. In the open-hearth process the bulk of manganese ferroalloy is added to the furnace during steelmak- ing, resulting in considerable manganese losses. With the basic oxygen converter the manganese ferroalloy can be added to the ladle at the same time as other ele- ments, improving the yield. The electric furnace can lower the unit consumption of manganese for a particular type of steel even more by further reducing the loss of manganese to slag through oxidation com- pared with the other processes. The unit consumption of manganese as ferroalloys per ton of raw steel produced in the United States in 1982 and 1983 was significantly below the levels of previ- ous years — the 1983 usage rate was about 75 pet of that in 1981. Just a few years ago, such a dramatic reduction over such a relatively short period of time was considered impossible. Although product mix is a relevant factor, the change has happened principally because of the rapid adoption of new steelmaking prac- tices whose benefits include a decrease in manganese processing losses. Most steelmakers have ceased the original re- fining practice of blowing all the oxygen on the top of the bath. The initial de- parture from the basic oxygen process (BOP) was the Q-BOP or OBM process in which all the oxygen is blown through bottom tuyeres to provide more efficient mixing and thus achieve higher yields, greater cleanliness, and low carbon lev- els. A modified form, K-BOP, blows only 40 pet of the total oxygen through the bottom, while the rest is top blown. Since the bottom-blown furnace has high capital requirements, several simpler processes requiring less capital have been developed by various steel compa- nies. They combine top blowing of oxygen and bottom stirring with inert gas. In some cases, bottom stirring is coupled with a small amount of bottom-blown oxy- gen. In addition to higher manganese residuals, these new technological devel- opments offer higher yields , less flux consumption, better aluminum recovery, 37 low carbon levels, increased scrap utili- zation, and better removal of impurities, at lower cost. It was previously thought that the only opportunities available to lower the spe- cific demand for manganese in steel would be evolutionary changes , such as — Electric furnace steelmaking, since a higher percentage of electric furnace production capacity would reduce manga- nese losses from oxidation compared with open-hearth and basic oxygen converter processes. External desulf urization , which uti- lizes calcium carbide or magnesium to lower the sulfur content of iron that is to be subsequently processed into steel. Argon-oxygen decarburization (AOD) , which allows better retention of easily oxidized materials such as manganese; extension of AOD to a wider range of al- loy and carbon steels would increase the efficiency of manganese utilization. Direct reduced iron (DRI) , since usage in steelmaking furnaces can lower manga- nese needs because of its low sulfur content. Continuous casting of raw steel , which increases the yield of steel products and lowers the amount of scrap that must be recycled, thus minimizing remelting (and attendant manganese loss) and increasing the overall efficiency of manganese uti- lization in the system. Packaging of manganese alloys , which avoids losses from abrasion and breakage of alloys during handling in the usual bulk form. Tighter specifications , since manganese content may be broader and higher than necessary to meet property requirements for some grades of steel. Whereas the recent decline of nearly 25 pet in unit manganese consumption, attributable largely to new steelmaking technology, occurred in only 2 yr, full attainment of the manganese conservation potential of the alternatives listed above, although of similar magnitude (20 to 30 pet) , is considered long term. Their conservation potential is probably in the range of 10 to 15 pet in the short term (several years). Most of the manganese that is lost from the steelmaking system goes to the slag. A portion of the slag is returned to the blast furnace, where some manganese is recovered in the pig iron. The propor- tion of slag that can be recycled is lim- ited by its phosphorus content because the phosphorus entering the blast furnace ends up in the pig iron and would build up excessively if sufficient slag were not discarded. Steelmaking slags are not a promising potential source for reclama- tion of manganese. The slags are low in manganese content (4.5 to 9 pet) and are not amenable to direct treatment by hydrometallurgical methods, instead re- quiring energy-intensive pyroraetallurgi- cal or combined pyrometallurgical-hydro- metallurgical processing. Also, existing slag dumps are usually intermixed with other refuse. Most manganese contained in steel scrap is oxidized and lost to slag when scrap is recycled in steelmaking furnaces. Nonferrous Alloys Manganese is used as a component of some nonferrous alloys to impart hard- ness, stiffness, and corrosion resist- ance. Aluminum alloys containing I pet or more manganese are used for bever- age cans and food handling equipment. Manganese bronzes (copper-base alloys strengthened by small additions of manga- nese) are found in marine propellers and fittings, gears, and bearings. High- manganese-content specialty alloys in- clude copper-manganese-nickel electrical- resistance alloys, which contain 10 pet or greater manganese, and alloys with high coefficients of thermal expansion for bimetallic elements of thermostats. Batterie s (62) Manganese dioxide has long been a com- ponent of the common dry-cell battery. Depending on costs and desired battery characteristics, the manganese dioxide that is used may be from certain natural ores, a synthetic form produced by elec- trolytic or chemical means, or a blend of 38 both materials. Manganese dioxide had been thought to act as a depolarizer by removing any hydrogen that formed, but according to current theory, it partici- pates directly in the electrochemical re- action of the cell. Substitution with alternative batteries is possible, but for economic reasons only to a limited extent. Chemicals and Miscellaneous (37, J37, 60, 62) Manganese ore is used as an oxidant in the production of hydroquinone, which has applications in photographic developers and in the production of certain types of rubber and plastic. Ore is also employed as a decolorizing agent to neutralize the iron content common in most glass sands. Potassium permanganate is a powerful oxidant frequently utilized in water treatment and purification, as well as a variety of other chemical applications. Manganese dioxide is used in the sealant of incandescent light bulb bases, and as part of the frits for bonding glass and porcelain to metal. Manganous oxide is utilized as an additive to livestock and poultry feeds, and as a component of welding rods and fluxes. Manganese sul- fate is used as a fertilizer supplement; manganese chloride as a textile dye and a magnesium alloy flux; and manganese per- sulfate as an oxidizing agent in the synthesis of organic compounds. Substi- tution is possible for some of the oxi- dant, chemical, and miscellaneous uses of manganese, but seldom where requirements call for the metal itself. SUPPLY ALTERNATIVES Domestic (56, 62 , 64 ) The Bureau of Mines investigated the availability of manganese from eight known domestic occurrences (table 13). These deposits were found to have demon- strated resources totaling 420 million mt , but with an average grade of only 10 pet contained manganese. Principally because of high benef iciation and trans- portation costs, prices substantially in excess of those currently prevailing in the market would be required for develop- ment, in the absence of a major cost- reducing technological breakthrough. Al- though annual production of domestic ore could theoretically reach a maximum of 900,000 mt of recoverable manganese, the lag time in bringing these individual sites on-stream would range from 3 to 6 yr. Since manganese can be moved and con- centrated readily in a number of geologic environments, many undiscovered concen- trations may exist. However, its lack of a distinctive geophysical expression and its abundance in subeconomic concentra- tions hinder standard geophysical and geochemical exploration techniques. On the basis of geologic inference, it has been suggested that the possibility of sizable, high-grade, U.S. deposits is greatest in the Atlantic and Gulf Coastal Plains and in the North Central States, but the level of understanding of ore formation is inadequate to predict a suf- ficiently small region of high potential. TABLE 13. - Domestic manganese resources Mine •tate Ore grade, Demonstrated pet resources, 10 3 mt AZ 15.0 5,895.5 AZ 8.75 8,441 CO 10.0 24,909 ME 8.87 260,000 ME 9.54 63,100 MN 7.84 48,960 MT 18.0 1,232 NV 13.2 7,230 Hardshell Mine Maggie Mine Sunnyside Mine Maple Mountain-Hovey Mountain. . North Aroostook District (Dud- ley and Gelot Hill) Cuyuna North Range (SW portion) Butte District (Emma Mine) Three Kids Mine 39 Foreign (56-57, bl, 65-66) There is no shortage of manganese worldwide — adequate reserves exist to meet foreseeable needs, but they occur primarily in the Republic of South Africa and the U.S.S.R. These nations are cur- rently the two largest producers of man- ganese ore. Although much of its produc- tion is considered submarginal by market economy standards, the U.S.S.R. prefers to meet its manganese requirements inter- nally and provides most of the manganese consumed by the other centrally planned economy countries as well. However, these countries have been increasing their imports of manganese from non- Soviet sources. In the future, market economy countries will likely continue to depend on a few suppliers for most of their manganese ore. The prominence of the Republic of South Africa is expected to increase because of its resource posi- tion and relatively cheap energy. Gabon, whose metallurgical-grade ore is among the richest in the world, will be able to increase output by nearly 50 pet when the Trans-Gabon Railroad is completed. Aus- tralia should also continue as a leading ore producer and export. Brazil's prin- cipal mine, Serra do Navio, will be de- pleted of reserves in the next decade, and while deposits in the Carajas region promise to fill the void, ore exports from that source are expected to be lim- ited in favor of conversion to manganese ferroalloys for export and captive use. India's role as a major ore supplier could diminish somewhat because of inter- nal needs, depending on developments in the Indian steel and ferroalloy indus- tries. While presently a moderate-scale world producer of relatively low-grade carbonate ore, Mexico has sufficient de- posits to support a substantial increase in production. Mexico thus appears to offer an opportunity for a secure, acces- sible, alternative source of manganese for the United States, although the ore requires roasting and blending with higher grade material. As with chromium, primary raw material supplies, i.e., manganese ore, may no longer be the main concern for the United States, because imports of manganese are increasingly in the form of ferroalloy. There is a clear and accelerating trend to convert ore to manganese ferroalloys by the ore-producing countries at the expense of production capacity in the United States. Of the major ore pro- ducers, only Gabon has no ferroalloy capacity as yet. Without adequate or alternative U.S. manganese ferroalloy capacity, the issue of a secure source of manganese has a different connotation. The major world producers of manganese ferroalloys are the U.S.S.R., Japan, China, the Republic of South Africa, Nor- way, and France. Ocean M inera ls (56) Typical deep-sea nodules contain 25 to 35 pet Mn on a dry basis, and the re- source potential of marine manganese crusts is currently being assessed. Pre- vious discussion has touched on the pres- ent impediments to ocean mining. Stockpile (62) Provided that the National Defense Stockpile materials are satisfactory for their intended purposes, quantities of chemical- and battery-grade manganese in inventory were in excess of stockpile goals, except for synthetic manganese dioxide. The inventory of metallurgical ore stood at 89 pet of the goal as of November 30, 1983, but the shortfall could be more than met by offset credits from inventories of ferroalloys and metal in excess of goals. In December 1982, it was announced that a portion of stockpiled manganese ore would be upgraded into high-carbon ferro- manganese as part of a program to Im- prove stockpile readiness and to maintain some domestic ferroalloy capacity. The plan called for the production of about 577,000 st of f erromanganese over a 10-yr period. In 1983 and 1984, GSA contracted for upgrading a total of approximately 128,000 st of ore. 40 SUMMARY OF DEMAND AND SUPPLY ALTERNATIVES The bulk of manganese consumed in the United States (about 90 pet) is used for its desulf urizing, deoxidizing, and alloying functions in ironmaking and steelmaking. The universal use of manganese in steelmaking results from its abundant supply and its low cost relative to that of other materials and of modified steelmaking practices that might accom- plish the same ends. From a practical standpoint there is no substitute for manganese. The phasing out of open-hearth steel- making has resulted in a corresponding decline in unit manganese consumption. Both the basic oxygen converter and the electric furnace result in improved yields of manganese. The adoption of new steelmaking prac- tices that combine top blowing of oxygen and bottom stirring with inert gas has been a major factor in reducing the unit consumption of manganese as ferroalloys per ton of raw steel produced by nearly 25 pet in only 2 yr. Other technological opportunities capa- ble of lowering the specific demand for manganese per ton of steel are evolution- ary changes, not breakthroughs. Full at- tainment of the manganese conservation potential of these alternatives could re- duce the unit manganese consumption by 20 to 30 pet. In the short run (several years) their conservation potential is probably in the range of 10 to 15 pet. Most of the manganese that is lost from the steelmaking system goes into the slag, but the proportion of slag that can be recycled is limited by its phosphorus content. Steelmaking slags are also not a promising potential source for economi- cal reclamation of manganese because of their low manganese content and lack of amenability to direct hydrometallurgical treatment methods. The quantity of manganese used in the United States for purposes other than ironmaking and steelmaking (nonferrous alloys, batteries, chemicals) amounts to only about 10 pet of demand. Domestic manganese deposits contain low-grade ore and would require market prices substantially in excess of those currently prevailing to warrant develop- ment. Bringing the individual sites on- stream would require from 3 to 6 yr. Mexico appears to offer an opportunity for a secure, accessible, alternative source of manganese ore for the United States. There is an accelerating trend to con- vert manganese ore to manganese ferro- alloys by the ore-producing countries, at the expense of production capacity in the United States and other consuming nations. U.S. imports of manganese fer- roalloys now substantially exceed those of manganese ore. PLATINUM-GROUP METALS BACKGROUND The platinum-group metals consist of platinum, palladium, iridium, osmium, rhodium, and ruthenium. They exhibit several remarkable properties including resistance to corrosion and oxidation even at high temperatures; extensive and sometimes unique catalytic activity; high melting points; and great strength. As a result, they are used as automotive, chemical process, and petroleum refining catalysts, and in electrical devices, dental supplies, jewelry, and glass manu- facturing. Of the six metals compris- ing the group, palladium and platinum together account for approximately 90 pet of consumption (table 14). In spite of the high initial cost, platinum-group metals continue to be used because they are generally superior to other less ex- pensive or more widely available materi- als, and in nondissipative uses, they ex- hibit excellent recyclability (table 15). A very small quantity of platinum-group metals is derived from domestic copper mining as a byproduct. About 10 pet of the annual supply consists of recycled metal. The remainder is imported, mostly as refined metal from the Republic of South Africa, the U.S.S.R., and the United Kingdom. The latter refines some 41 TABLE 14. - Platinum-group metals sold' to consuming industries in the United States (Thousand troy ounces) Use Pt Pd Ir Os Rh Ru Total 3 Quantity pet 1981 Catalysts: 447 88 78 112 29 28 19 72 129 21 90 345 3 15 255 30 ( 2 ) 2 1 4 1 ( 2 ) 1 ( 2 ) ( 2 ) 30 9 12 4 4 ( 2 ) 4 1 ( 2 ) 52 27 1 ( 2 ) 6 607 111 231 500 36 47 275 114 32 6 12 26 2 2 14 6 873 889 8 1 62 88 1,921 100 1982 Catalysts : 478 22 64 90 21 16 23 68 118 21 129 312 ( 2 ) 8 311 27 ( 2 ) 1 1 5 ( 2 ) 1 ( 2 ) 2 ( 2 ) 1 26 ( 2 ) 7 9 2 3 ( 2 ) 2 64 21 ( 2 ) ( 2 ) 20 623 43 264 438 23 29 335 118 33 2 14 23 1 2 18 6 Total 3 780 926 11 1 50 105 1,873 100 1983 Catalysts: 508 38 65 75 15 10 17 68 172 50 40 250 ( 2 ) 7 344 60 ( 2 ) 1 1 1 ( 2 ) 1 ( 2 ) 1 ( 2 ) 1 20 4 8 2 2 ( 2 ) 8 ( 2 ) 55 71 1 ( 2 ) 17 700 89 165 406 17 21 362 154 37 5 9 21 1 1 19 8 Total 3 797 922 5 1 44 145 1,914 100 Primary and non- 2 Less than 1/2 un 3 Data may not add toll-refined secondary metals. it. to totals shown because of independent rounding. TABLE 15. - Secondary platinum-group metals toll-refined in the United States (Thousand troy ounces) Metal 1981 1982 1983 Metal 1981 1982 1983 Pt 521 607 8 2 394 431 10 1 434 457 6 1 Rh 35 18 27 6 42 56 Ir Total ' 1,191 868 995 Data may not add to totals shown because of independent rounding, 42 South African and Canadian material, but world mine production of platinum- group metals is virtually the exclusive domain of the U.S.S.R. and the Republic of South Africa. Recent U.S. net import reliance has been 80 pet or more of ap- parent consumption. The consumption of all platinum-group metals totaled 1.914 million tr oz in 1983; the highest level of platinum-group metal consumption was 2.756 million tr oz in 1979. Producer and dealer prices in 1983 were $475/tr oz and $424/tr oz respectively for platinum, and $130/tr oz and $136/tr oz respectively for palladium. The U.S. demand for platinum-group met- als collectively is expected to grow at an average annual rate of 2.9 pet from 1981 to the year 2000. Table 16 contains world production of platinum-group met- als, world reserves, and imports by the United States. USES AND DEMAND ALTERNATIVES Catalysts Automotive Emission Control (67-71) The most significant event affecting the consumption of platinum-group metals in the United States has been their adop- tion as catalysts for the control of auto exhaust emissions. From 1965 through 1974 the automotive industry was able to comply with exhaust emission standards by engine modifications, but to the detri- ment of fuel economy and performance. Additional reductions in emissions man- dated by more restrictive standards led to the incorporation of catalytic con- verters in the exhaust system, which allowed the engine to operate with more effective ignition timing, thereby im- proving economy and performance. Thus, the automotive industry became the single largest consumer of platinum in the United States (while the petroleum indus- try also had to increase its use of plat- inum catalysts for the production of lead-free gasoline required by auto- mobiles equipped with converters). Al- though many potential catalyst materials have been examined since the late 1960's, to date only platinum-group metals, cur- rently combinations of platinum, palladi- um, and rhodium (average loading ratio 10.3:3.9:1), have shown the necessary ef- ficiency and durability. The possibility that a suitable base-metal catalyst may be developed cannot be discounted, but this would constitute a breakthrough and therefore cannot be predicted to occur at any particular point in time. Although the metal is virtually intact at the end of a converter's useful life, reclamation of platinum-group metals from catalytic converters presents a complex problem. The combination of low concen- trations of precious metals (averaging 0.079 tr oz per unit) and difficulties in converter collection presents technical and logistical challenges. The total amount of precious metals involved is significant — about 6.5 million tr oz of platinum-group metals have been sold to the U.S. automotive industry from 1974 through 1983. Approximately 80 pet of the amount is still contained on operat- ing vehicles, but only 15 to 20 pet of the remainder has been recycled. Com- plete recycling of all platinum-group metals does not occur because a portion is lost during normal life; not all is recoverable by refiners, especially if the catalyst is contaminated; and many converters are lost to scrap shredders or are being held by speculators. At pres- ent, costs are high, the market is specu- lative, and supply is erratic, but as industry awareness and the efficiency of the collection chain (dismantlers, collectors, decanners, and refiners) im- prove, recycling should increase. By 1988, an estimated 8.5 million cars per year will be scrapped. One estimate of the extent of platinum-group metal recov- ery that is possible projects a 70-pct rate ( 70 ) . Short-term solutions to a lack of platinum-group metal availabil- ity, such as a relaxation of emission standards whereby non-precious-metal cat- alysts could achieve a reduced emission standard or a moratorium on the use of converters, obviously compromise the quality of the environment. 43 TABLE 16. - World platinum-group metal production, reserves, and U.S. imports (Thousand troy ounces) Country Australia Belgium-Luxembourg Canada China Colombia Costa Rica Ethiopia Finland Germany, Federal Republic of Hong Kong Italy Japan Korea, Republic of Mexico Netherlands No rway Panama Peru Singapore South Africa, Republic Spain Sweden Switzerland Taiwan U.S.S.R .c of United Kingdom. United States . , Venezuela , Yugoslavia. Zimbabwe , Other Total 4 , Production 1981 1982 p 15 383 15 ( 2 ) 4 3 36 3,110 3,350 7 4 8 6,931 14 228 20 ( 2 ) 9 3 43 2,600 3,500 8 3 4 6,431 1983' 14 167 20 ( 2 ) 9 3 59 2,600 3,600 6 3 4 'Less than 1 million tr oz ^Recovered from imported totals shown because of in 6,482 Reserves NA 8,000 NA (') NA NA 790,000 190,000 1,000 NA (') NA 1,000,000 U.S. imports 1981 26 140 78 4 10 3 19 53 3 1 79 42 33 6 11 621 9 6 37 359 303 7 2,850 1982 5 107 95 1 3 6 31 28 4 162 27 27 1 1,195 2 5 35 405 339 18 2,494 1983 20 208 231 7 7 4 3 83 1 54 10 1 78 35 17 5 1,219 6 23 61 58 430 639 15 1 2 3,218 NA Not available. 2 Less than 1/2 unit. 4 Data may not add to 5 Rounded. ore. dependent rounding, Ceramics present an opportunity for heat engines to operate at temperatures beyond those attainable by current metal- lic engines. This capability translates into enhanced systems performance in the form of greater fuel economy and substan- tially reduced emissions. Should ce- ramics become the material of the future generation of heat engines, there would be a major reduction in the amount of platinum-group metals required to control automotive emissions (28). Petroleum Refining (67) The use of platinum-group metals in petroleum refining occurs mostly in hy- drocarbon reforming with conventional (platinum) or bimetallic (platinum and rhenium or iridium) catalysts. Other 44 refining processes (hydrocracking, iso- merization, hydrotreating) are relatively minor uses for platinum and palladium, and the processes rely only partially on these metals for catalysts. The substitution of other materials, such as molybdenum, for platinum in re- forming catalysts would reduce the ef- ficiency of the process. Fortunately, there is a large inventory of platinum- group metals in place. The catalysts are recycled on a toll-refined basis, re- turned as sponge, and remanuf actured into new catalysts. The loss rate is very low (97 pet of the metal in spent refining catalyst is reclaimed) , which would en- able the petroleum refining industry to continue to operate without the constant need for new metal. Chemical Processing {bl_, 72-74) The oxidation of ammonia to nitric acid is the major chemical process employing platinum-group metal catalysts. Nitric acid is an intermediate in the synthesis of ammonium nitrate (fertilizer, explo- sives) and is used as a reactant or pro- cess chemical in the production of adipic acid (nylon fibers, plastics) and in the synthesis of intermediates which are fur- ther processed into compounds such as aniline (rubber, dyes, pharmaceuticals, pesticides) and diisocyanates (polyure- thane foams, plastics, elastomers). Ni- tric acid is also used directly for stainless steel pickling. The catalyst consists of a platinum wire woven into a fine mesh gauze with about 10 pet Rh added to increase strength and efficiency and reduce catalyst losses. Typically a "pack" of 20 gauzes is utilized. Some on-site regeneration of the catalysts can be performed, and metal losses can be re- covered (55 to 70 pet) with catchment gauzes and mechanical filters, but after losing a certain percentage of its ini- tial weight, the catalyst is replaced and recycled. An alternative, cobalt oxide with additions of other metal oxides, is available at lower cost, but certain as- pects of its performance are inferior. It appears unlikely that platinum gauze will be superseded by this base metal catalyst. Noble metal catalysts are broadly used elsewhere in the chemical and pharmaceu- tical industries, but their use in large- scale processes such as organic oxidation (acetaldehyde , acetone, acetic anhydride, acetic acid, vinyl acetate, oxo alco- hols), hydrocarbon alkylation and isomer- ization, and hydrogenation is relatively recent. Often platinum-group metals are not the primary catalysts but rather are used in selective applications. As with petroleum refining catalysts, the recy- clability of platinum-group metals uti- lized as chemical process catalysts is high — about 85 pet. Electrical and Electronic (67) These applications depend on the chemi- cal inertness and thermal stability of platinum-group metals and are probably more numerous, involve more product forms, and utilize a wider range of alloy compositions than any other industry. As expected, home scrap and prompt indus- trial scrap are recycled to a far greater extent than obsolete scrap, although the Department of Defense operates a program to recover platinum-group and other pre- cious metals from surplus, outdated, and damaged Government items. Contacts Low-voltage, low-energy contacts, such as found in telephone switching equipment and relays require materials that provide low and stable contact resistance in var- ious environments for as long as 40 yr by exhibiting minimal corrosion and wear. Platinum-group metals, especially palla- dium, have been used extensively since the lower cost of palladium offsets the generally superior performance of gold. However, replacement of electromechanical devices with electronic switching systems is displacing platinum-group metals from this sector. Certain contacts (relays, voltage regu- lators, thermostats, switches, slip-ring assemblies) operate at higher voltages and contact forces and may require better wear and arc erosion resistance. Medium- to heavy-duty relays and switches use platinum alloyed with 5 to 14 pet Ru. 45 Palladium-silver alloys also are used in this way. For slip-ring assemblies com- plex platinum-group metal alloys are used as well as electrodeposited rhodium. Thin- and Thick-Film Circuits In thin-film circuits and some sili- con integrated circuitry, thin layers of platinum or palladium are applied by sputtering or evaporation to provide re- liable conductor adhesion. In thick-film and hybrid-integrated circuits, composi- tions of gold and platinum or palladium, or of palladium and silver, applied as screened-on pastes are used for conduc- tors. Ruthenium applied as a ruthenate paste and converted to ruthenium oxide is used as a resistor material on these circuits. Platinum-group metal use in thick-film and hybrid integrated circuits may be challenged by copper pastes. Thermocouples and Furnace Components Various combinations of platinum, rho- dium, and iridium are utilized in typi- cal high-temperature thermocouple sys- tems. Ultrapure platinum is used as a resistance thermometer; platinum with 10 to 40 pet Rh is used for windings in fur- naces operating to 1,800° C in air; un- alloyed platinum and rhodium are used for heater windings. Electrodes and Miscellaneous Multilayer ceramic capacitors are a rapidly growing end use for palladium in the form of silver-palladium alloy elec- trodes. However, lower cost nickel and lead alternatives are being evaluated. Ruthenium oxide is used as a coating on dimensionally stable titanium anodes used in the production of chlorine and caustic soda. Platinum and platinum-palladium alloys are used as insoluble anodes for the cathodic protection of ships and pipelines. Materials for spark plug electrodes include platinum with 4 pet W, platinum-rhodium alloys, and iridium (es- pecially in heavy-duty aircraft engine spark plugs). Fine platinura-iridium wire is used as fuse wire for explosive detonators . Glass (67 , 75_) Platinum and platinum-rhodium alloys are used in a wide variety of glass han- dling and forming equipment because of their high melting point, hot strength, low oxidation rate, good corrosion re- sistance, and noncontaminating nature. Pure platinum is used for glass melting tanks, stirrers, and crucibles for melt- ing high-quality optical and special glasses. Platinum with 10 pet Rh is used for the bushings and baskets needed in the production of glass fibers. Platinum with 40 pet Rh is used for crucible liners, structures for conveying mol- ten glass, fiber-optics-forming devices, laser-glass melters, and stirrers for glass horaogenization. Iridium is used as an extrusion die material for glasses of high melting points. Very low metal losses (about 2 to 4 pet) are experienced in these uses. Worn parts are recycled on a toll basis and returned to the industry for fabrication into new parts. Jewelry (67) Platinum-group metal alloys, commonly platinum with 10 pet Ir , platinum with 5 pet Ru , platinum with 4 pet Pd , and pal- ladium with 5 pet Ru , are used for jew- elry in cast and wrought form for maximum prestige, reliability, and gem retention. Rhodium as a thin electrodeposit is often used over these or silver jewelry to pro- vide added whiteness, wear resistance, and immunity to tarnishing. In addition, a variety of platinum-group metal-con- taining inks and pastes are used for decoration of china, glass, and ceramics. Jewelry certainly seems to be an end use that could be easily dispensed with, should the availability of plat- inum-group metals become limited. Ironi- cally, however, Japanese consumption of platinum for jewelry, which has almost singlehandedly made jewelry the world's largest end use for the metal, has made large quantities of its copruducts available . 46 Dental and Medical (67) Platinum, palladium, and a variety of complex gold-silver-copper alloys that contain these elements find wide use as dental restorative materials and bone prosthetic treatments. Palladium is emerging as the precious metal of choice, replacing gold, platinum, and platinum- iridium alloys because it provides suffi- cient strength at lower cost. Primary medical uses of platinum-group metals include platinum coordination compounds used in cancer chemotherapy and platinum- iridium alloy body implant probes, elec- trodes, and needle tubing. Mis cellaneous (67) Laboratory Apparatus Because of its resistance to high tem- peratures and chemical attack, platinum has found many uses in chemical labora- tories, including crucibles or boats made from platinum hardened with rhodium for fusions or combustions, electrodes of platinum hardened with iridium for elec- trolytic methods and electrodepositions , thermocouples, thermistors, instrument components, and research compounds. Crystal Growth Platinum, platinum alloys with rhodium or iridium, and iridium find use as cru- cible materials in the flux and melt growth of single crystals of oxide com- pounds that melt at high temperatures. These include sapphire for semiconductor substrates, gadolinium-gallium-garnet for bubble memory devices, neodymium-doped yttrium-aluminum-garnet and ruby for op- tically pumped lasers, synthetic gem- stones, and lithium columbate and lith- ium tantalate modulator and transducer materials. a few thousand troy ounces annually and accounts for less than 1 pet of domestic consumption. The Bureau of Mines inves- tigated the availability of platinum (only) from domestic sources (table 17) and concluded that only one deposit, the Salmon River (Goodnews Bay Mine) , was capable of producing platinum at $420/ tr oz, the January 1980 producer price. This mine has been the largest producer of primary platinum in the United States, totaling 641,000 tr oz , and it has been estimated that the deposit could yield an additional 500,000 tr oz at a rate of 10,000 tr oz/yr. Production ceased after 1975 but resumed on a limited basis from 1980 to 1982. The Salt Chuck deposit in Alaska has also been an intermittent pro- ducer of platinum-group metals, but total mineralized material and demonstrated re- sources are quite limited. In 1983, the three companies involved in the exploration of the Stillwater Com- plex in Montana formed a new three-way partnership to further evaluate the de- posit. Factors that have held back the development of the Stillwater Complex in- clude environmental concerns for the sur- rounding wilderness area, locations of tailings disposal sites, remoteness and climate of the site, and fluctuations in platinum-group metal demand and prices. The companies involved with the deposits in the Duluth Gabbro in Minnesota have ceased exploration activity there. The relative mix of platinum-group metals in both the Stillwater Complex and the Du- luth Gabbro greatly favors palladium over platinum (78 versus 18 to 20 pet), which does not correspond well to industrial demand. The total amount of recoverable plati- num potentially available from the U.S. deposits analyzed in the Bureau study TABLE 17. - Total U.S. platinum resources 1 SUPPLY ALTERNATIVES Domestic (67, 76-77) Platinum and palladium are recovered in the United States as byproducts of copper refining, but this production totals only (Million troy ounces) Contained 3 Recoverable 2 includes Salmon River, AK; Ely Spruce, MN; Minnamax, MN; Stillwater, MT; Ana- conda, MT. 47 is about 2.3 million tr oz . At assumed production capacities, these deposits are capable of producing only 113,000 tr oz annually — less than 15 pet of U.S. requirements. Foreign (67 , 76-_77) Nearly all of the world's reserves of platinum-group metals are in the Republic of South Africa and the U.S.S.R. The grade of the South African deposits en- ables platinum-group metals to be mined as the principal product, unlike most other occurrences. Canada, the third- largest producer, presents a nearby, se- cure source of supply, but platinum-group metal production is limited by its sta- tus as a byproduct of copper and nickel. Likewise, Australian output is also rele- gated to a byproduct role. Although pro- duction in Colombia occurs as a coproduct of gold and silver, production facil- ities there are aging. Platinum-group metal deposits in Brazil are not under development . At present the entire platinum-group metal output of these alternative (to the Republic of South Africa and the U.S.S.R.) countries represents only about 20 pet of U.S. primary demand. It ap- pears that the Republic of South Africa is assured of continuing as the major supplier of platinum-group metals to the United States. Stockpile ( 67 , 77) Only three of the platinum-group met- als — platinum, palladium, and iridium-- are held in the National Defense Stock- pile. The inventories of each, however, are considerably below their goals: platinum, 34 pet; palladium, 42 pet; iri- dium, 26 pet. Since 1982 GSA has pur- chased a total of 10,900 tr oz of iridium from the stockpile. Strictly speaking, none of the previous stockpile inven- tories of platinum-group metals meets both the current chemical requirements for purity and physical requirements for form, since the inventory is in bar, plate, or sheet form, in contrast to more recent specifications of metallic sponge, and the purity levels of a portion of the stockpile preclude consumption in the highest purity applications. SUMMARY OF DEMAND AND SUPPLY ALTERNATIVES Although many potential auto emission catalyst materials have been examined, only platinum-group metals have shown the necessary efficiency and durability. The development of a suitable base metal catalyst would constitute an unforesee- able breakthrough. The combination of low concentrations of precious metals and difficulties in converter collection presents technical and logistical challenges to automotive catalyst reclamation. However, it is es- timated that a 70-pct metal recovery rate could be achieved. A relaxation of auto emission stan- dards, or a moratorium on the use of cat- alytic converters, could accomplish con- siderable conservation of platinum-group metals in a short time, but such action would comprise environmental quality. Platinum petroleum-refining catalysts are highly recyclable. Substitute cat- alysts such as molybdenum reduce process efficiency . Nitric acid manufacture is the major chemical process employing platinum-group metal catalysts. Some on-site catalyst regeneration can be performed, and recy- clability is very good. A lower cost co- balt oxide alternative is available, but certain performance aspects are inferior. Electrical and electronic applications of platinum-group metals are probably more numerous, involve more product forms, and utilize a wider range of alloy compositions than any other industry. Electronic switching systems, printed circuits, and metals such as gold, sil- ver, and tin-lead alloys offer alterna- tives in many applications. Platinum-group metals are utilized in a variety of glass handling and forming equipment, but very low metal losses are experienced in these uses; worn parts are recycled on a toll-refined basis. Gold and silver could readily substi- tute for platinum in jewelry uses. 48 Many dental and medical applications now using palladium could revert to the traditional material, gold, albeit at much higher cost. Regardless of price, at assumed pro- duction capacities, the combined plat- inum deposits in the United States could produce less than 15 pet of annual requirements . Nearly all of the world's platinum- group metal reserves are in the Republic of South Africa and the U.S.S.R. The Republic of South Africa seems assured of continuing as the major supplier of platinum-group metals to the United States. CONCLUSIONS COBALT Domestic Supply Current essential cobalt needs are estimated at about 50 pet of present consumption. Substitution Superalloys . - Significant amounts of cobalt could be replaced, but costly and time-consuming alloy optimization and engine certification programs would be required. Magnetic alloys . - An estimated 20 pet of current cobalt use is deemed essential. Cemented carbides. - Cobalt-free mate- rials cannot be considered as practical general alternatives. Wear-resistant alloys . - Where cobalt is required, lower cobalt substitutes will suffice. Tool and maraging steels. - Cobalt-free grades have been developed. Catalysts . - Hydrotreating is amenable to substitution. Paint drier s. - Elimination or reduc- tion of cobalt would incur substantial penalties in convenience and product quality. Other chemicals . - A 60-pct reduction in cobalt use could be accomplished. Processing Near-net-shape processes can achieve improved yields of usable product. Recycling Most in-house and prompt industrial scrap is recycled, and cobalt is gener- ally recovered; obsolete, low-grade, and mixed alloy scrap is not efficiently recycled. Development of domestic deposits would require a cobalt price of $20/lb to $25/ lb and could take 5 yr. Foreign Supply The most competitive cobalt resources in North America are the nickel deposits of Canada. CHROMIUM Current U.S. chromium consumption could be reduced by approximately one-third us- ing available technology. Substitution Stainless steels . - Chromium savings can be accomplished by partial replace- ment of the chromium in excess of 12 pet with other alloying elements, by com- pletely replacing stainless steel with a different metallic or nonmetallic materi- al, by employing thinner gauge or longer lasting high-chromium alloys, or by using surface modification techniques such as cladding, plating, and coating. Alloy steels . - Chromium content can be eliminated or reduced by using other alloying elements that also influence hardenability. Tool steels . - Substitution with sin- tered carbides entails serious cost penalties. Alloy cast irons . - Low- or no-chromium alternatives are available for roll, abrasion-resistant, and engineering types. Superalloys . - A high chromium content is essential only at the surface, not for mechanical properties. 49 Other alloys . - Substitutes for chro- mium are readily available in alloys of aluminum, titanium, and copper. Pigments and paints. - Replacement of chromium with proven alternatives would incur a substantial cost penalty or limit the number of available colors. Leather tanning. - No practical substi- tutes exist. Metal finishing and treatment.- Decora- tive electroplating could be replaced by chromium-free materials such as plastics, or by painting the substrate; electroless nickel provides an alternative to hard plating. Drilling mud additives. - No satisfac- tory substitutes exist for deep wells. Water treatment compounds . - No chro- mium-free corrosion inhibitors have been proven satisfactory at temperatures of 150° F or higher; alternatives are avail- able for less critical applications. Wood treatment. - Nonchromium wood pre- servatives are readily available but do not offer comparable paintability . Processing Wider application of duplex refining systems for steel production appears to be a promising process area for achieving substantial conservation of chromium. Powder metallurgy techniques, such as rapid solidification and near-net-shape, offer possibilities for chromium conser- vation by producing unique properties via alloy microstructure and by generating less scrap. The continuing decline in open- hearth furnace steelmaking has dimin- ished the importance of chrome-bearing refractories. Recycling Stainless steel scrap is the major source of secondary chromium supply. Collection and processing costs hinder large-scale recovery from other metallur- gical industry processes. Domestic Supply No domestic chromite deposits are con- sidered suitable for development with existing technology at current market prices. Foreign Supply The known chromite resources of the Republic of South Africa and Zimbabwe are so vast that eventual concentration of supply there is expected. With the trend toward conversion of chromite to f errochromium in the ore-producing coun- tries, it is probable that future world f errochromium production will also be- come highly concentrated in these two countries . MANGANESE Substitution From a practical standpoint there is no substitute for manganese in steelmaking. Processing The recent adoption of new steelmaking practices that combine top blowing of oxygen and bottom stirring with inert gas has been a major factor in reducing the unit consumption of manganese. Full attainment of other technological opportunities could eventually reduce the unit manganese consumption by 20 to 30 pet (in the short run 10 to 15 pet). Recycling The recyclability of steelmaking slag is limited by its phosphorus content. Slags are also not a promising potential source for economical reclamation of man- ganese because of their low manganese content and lack of amenability to direct hydrometallurgical treatment methods. 50 Domestic Supply Domestic manganese deposits contain low-grade ore and would require mar- ket prices substantially in excess of those currently prevailing to warrant development. Fore ign Supply Mexico appears to offer an opportunity for a secure, accessible, alternative source of manganese ore for the United States. There is an accelerating trend to con- vert manganese ore to manganese ferro- alloys by the ore-producing countries at the expense of production capacity in the United States and other consuming nations. PLATINUM-GROUP METALS Substitution Automotive emission control cata- lysts . - The development of a base metal catalyst with suitable efficiency and durability would constitute an unforesee- able breakthrough. Petroleum refining catalysts , - Substi- tutes such as molybdenum reduce process efficiency. Chemical processing cataly sts. - A low- er cost cobalt oxide alternative is available for nitric acid production, but certain performance aspects are inferior. Electrical and electronic . - Electronic switching systems, printed circuits, and metals such as gold, silver, and tin- lead alloys offer alternatives in many applications . Jewelry . - Gold and silver could read- ily substitute for platinum. Dental and medical . - Many applications now using palladium could revert to the traditional material, gold, albeit at much higher cost. Recycling The combination of low concentrations of precious metals and difficulties in converter collection presents technical and logistical challenges to automotive catalyst reclamation. Platinum petroleum refining and chemi- cal processing catalysts are highly recyclable. Very low metal losses are experienced in glass handling and forming equipment; worn parts are recycled on a toll-refined basis. Regulations A relaxation of auto emission standards or a moratorium on the use of catalytic converters could accomplish considerable conservation of platinum-group metals in a short time, but such action would com- promise environmental quality. Domestic Supply At assumed capacities, production from U.S. platinum deposits would be capable of satisfying less than 15 pet of annual domestic requirements. Foreign Supply Nearly all of the world's platinum- group metal reserves occur in the Repub- lic of South Africa and the U.S.S.R. REFERENCES 1. Morgan, J. D. Strategic Materials Scarcities: Real and Imagined. Pres. at Natl. Conf. on Strategic Resour. , Wash- ington, DC, Dec. 1, 1981, 14 pp.; avail- able upon request from R. J. Foster, Bu- Mines, Washington, DC. 2. Ayres , R. U. , A. Shapanka, and D. Robertson. Critical Materials: A Problem Assessment. U.S. Natl. 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