c5* n v** -i- x/ .•»& %/ .-^•- * ,» % V * :W^: ^°* ISp: a? o • °^ *•-•' a ' ^ ' ^3 V • ^''TfiW 5 ' . ; . y > v • ' • °* 'C* fife ^^ ^ * w ■ 0^ o°" "«. ^c . ^•'••■'•v ^■••"•••■/ \w Vw w/ \ ,; --. U '' ' A '^ f +. *^n< .♦ V ^ «p> -o.o" <{? O •.,,.* .0'' %0 * „ - n ° AV < o by lag- *b V ^ ( lV^, A*^ aV^ :.^} : : <-. .G' Bureau of Mines Information Circular/1985 Primary Lead and Zinc Availability Market Economy Countries A Minerals Availability Program Appraisal By G. R. Peterson. K. E. Porter, and A. A. Soja UNITED STATES DEPARTMENT OF THE INTERIOR ' AMINES 75TH A*^ Information Circular 9026 1 1 Primary Lead and Zinc Availability Market Economy Countries A Minerals Availability Program Appraisal By G. R. Peterson, K. E. Porter, and A. A. Soja 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 ot the Interior has responsibility for most of our nationally owned public lands and natural resources. This includes fostering the wisest use of our land and water 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. THms Library of Congress Cataloging in Publication Data: Peterson, G. R. (Gary R.) Primary lead and zinc availability— market economy countries. (Information circular / United States Dept. of the Interior, Bureau of Mines ; 9026) Bibliography. Supt. of Docs, no.: I 28.27:9026. 1. Lead industry and trade. 2. Zinc industry and trade. 3. Lead mines and mining. 4. Zinc mines and mining. I. Porter, K. E. (Ken- neth E.). II. Soja, A. A. (Audrey A.). III. Title. IV. Series: Infor- mation circular (United States. Bureau of Mines) ; 9026. *&2aS~U4— fHD9539.L4] 622s [338.2'744] 84-600357 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 ,\ ^ ^ 111 PREFACE The Bureau of Mines is assessing the worldwide availability of nonfuel criti- cal minerals. The Bureau identifies, collects, compiles, and evaluates information on active, developed, and explored mines and deposits and mineral processing plants worldwide. Objectives are to classify domestic and foreign resources, to identify by cost evaluation resources that are reserves, and to prepare analyses of mineral availability. This report is part of a continuing series of reports that analyze the avail- ability of minerals from domestic and foreign sources. Questions about these re- ports should be addressed to Chief, Division of Minerals Availability, Bureau of Mines. 2401 E Street, NW., Washington, DC 20241. IV UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT g/t gram per metric ton pet percent kg kilogram St short ton km kilometer t metric ton lb pound tr oz troy ounce It long ton t/yr metric ton per year m meter yr year CONTENTS Page Preface iii Abstract 1 Introduction 2 World lead and zinc industries 3 Lead industry 3 Consumption 4 Trade patterns 4 Secondary sources 5 Zinc industry 5 Consumption 6 Trade patterns 7 Secondary sources 7 Evaluation methodology 7 Lead and zinc resources 9 Geology of lead and zinc deposits 15 Mining methods and operating costs 16 Surface mining 17 Underground mining 17 Beneficiation methods and operating costs 18 Smelting and refining 18 Lead smelting 20 Conventional blast furnace 20 Imperial smelting furnace 21 Lead refining 21 Pyrometallurgical 22 Electrolytic 22 Page Zinc refining 22 Electrolytic 22 Imperial smelting furnace 23 Electrothermic 23 Horizontal retort 23 Vertical retort 24 Operating costs 25 Mine and mill 25 Lead mines and deposits 25 Zinc mines and deposits 25 Smelting and refining 26 Total production costs 27 Lead 27 Zinc 28 Capital costs 29 Availability of lead and zinc 30 Lead 30 Zinc 32 Importance of silver as a byproduct of lead and zinc production 37 Demand for lead and zinc '. 39 Conclusions 40 References 40 Appendix. — Geologic characteristics of major lead and zinc deposits in market economy countries 41 ILLUSTRATIONS 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 1.: 16. 17. 18. 10. 20. 21. 22. Classification of mineral resources 2 Flowchart of MAP evaluation procedure ' 3 Percent share of contained lead in market economy countries 9 Percent share of contained zinc in market economy countries 9 Share of annual ore capacity, by mining method, for producing and undeveloped lead and zinc mines and deposits lg Basic flowsheet for a typical copper-lead-zinc flotation mill ....'.' 18 Simplified schematic of a typical lead smelter using conventional blast furnace technology 20 Simplified schematic of an Imperial smelting furnace plant 21 Simplified schematic of pyrometallurgical lead refining 22 Simplified schematic of an electrolytic zinc refinery 23 Simplified schematic of an electrothermic zinc plant 24 Simplified schematic of a vertical retort zinc plant 24 Total recoverable lead from lead mines and deposits in market economy countries and the U.S 30 vailability of lead as a byproduct of primary zinc mines and deposits in market economy countries 31 Total recoverable lead from producing mines and undeveloped deposits in market economy countries and the United States 31 il annual availability of primary lead from producing lead mines in market economy countries and the United States 32 Potential annual availability of primary lead from undeveloped deposits in market economy countries and the United States 32 Total recoverable zinc from market economy countries, the U.S., Australia, and Canada ..... ..... 33 availability of zinc as a byproduct of primary lead mines and deposits in market economy coun- tries and the United States 33 Total availability of zinc as a byproduct of primary copper mines and deposits in market economy countries 00 Total recoverable zinc from producing mines and undeveloped deposits in market economy countries and the United States 34 annual availability of zinc from producing zinc mines in market economy countries and the United States 35 VI Page 23. Potential annual availability of zinc from undeveloped deposits in market economy countries and the United States 35 24. Total availability of lead from mines and deposits in market economy countries with byproduct silver at varying prices 35 25. Total availability of zinc from mines and deposits in market economy countries with byproduct silver at varying prices 37 TABLES 1. World lead mine production, 1961, 1971, and 1981 4 2. World primary and secondary lead production in 1981 4 3. U.S. lead import, export, and consumption for 1980-81 5 4. World zinc mine production, 1961, 1971, and 1981 6 5. U.S. zinc import, export, and consumption for 1980-81 7 6. Byproduct prices used in the economic evaluations 8 7. Summary of demonstrated lead and zinc resource values 9 8. Summary of January 1981 minable resource values for mines and deposits evaluated as lead properties, with minable resources and weighted-average feed grades 10 9. Summary of January 1981 minable resource values for mines and deposits evaluated as lead prop- erties, with minable resources and weighted-average grades for byproduct zinc 10 10. Summary of January 1981 resource values for mines and deposits evaluated as zinc properties, with minable resources and weighted- average feed grades 10 11. Summary of January 1981 minable resource values for mines and deposits evaluated as zinc properties, with minable resources and weighted- average grades for byproduct lead 10 12. Summary of January 1981 minable resource values for mines and deposits evaluated as copper proper- ties, with minable resources and weighted-average grades for byproduct lead 11 13. Summary of January 1981 minable resource values for mines and deposits evaluated as copper properties, with minable resources and weighted- average grades for byproduct zinc 11 14. Mines and deposits evaluated as lead operations 11 15. Mines and deposits evaluated as zinc operations 12 16. Mines and deposits evaluated as copper operations with lead and zinc as major byproducts 15 17. Mining methods and costs for producing and undeveloped lead and zinc mines and deposits 17 18. Estimated average mill capacity and operating cost 18 19. Market economy country 1981 lead and zinc smelting and refining capacity, by region 18 20. Comparison of 1968 and 1981 lead smelting and refining methods 18 21. Comparison of 1958, 1968, and 1981 zinc refining methods 20 22. Typical smelter and refinery recoveries and product grades 20 23. Estimated mine and mill operating costs for producing and undeveloped lead mines and deposits . . 25 24. Estimated mine and mill operating costs for producing and undeveloped zinc mines and deposits ... 26 25. Typical smelter schedules 26 26. Estimated total production costs for producing and undeveloped lead mines and deposits 27 27. Estimated total production costs for producing and undeveloped zinc mines and deposits 28 28. Capital costs for undeveloped lead and zinc deposits 29 29. Comparison of estimated long-run average total costs of potential zinc metal production from pri- mary zinc mines and deposits 35 30. Comparison of estimated zinc metal production as a byproduct from lead mines and deposits at the estimated long-run average total costs of primary lead production 36 31. Comparison of estimated zinc metal production as a byproduct from copper mines and deposits at the estimated long-run average total costs of primary copper production 36 32. Comparison of estimated long-run average total costs of potential lead metal production from pri- mary lead mines and deposits 36 33. Comparison of estimated lead metal production as a byproduct of primary zinc mines and deposits at the estimated long-run average total costs of primary zinc production 36 34. Comparison of estimated lead metal production as a byproduct from copper mines and deposits at the estimated long-run average total costs of primary copper production 37 35. Total recoverable silver as a byproduct of potential lead and zinc production 37 36. Weighted-average total cost of production per pound of lead at various prices of byproduct silver . . 38 37. Weighted-average total cost of production per pound of zinc at various prices of byproduct silver . . 38 PRIMARY LEAD AND ZINC AVAILABILITY-MARKET ECONOMY COUNTRIES A Minerals Availability Program Appraisal By G. R. Peterson, 1 K. E. Porter, 2 and A. A. Soja 3 ABSTRACT To determine the availability of lead and zinc from demonstrated resources, the Bureau of Mines evaluated 235 mines and deposits in 31 market economy countries. Of the 235 mines and deposits evaluated for this study, 186 were evaluated as zinc operations. 30 as lead operations, and 19 as copper operations. Demonstrated lead-zinc resources of market economy countries in 1981 were approximately 4.3 billion metric tons (t) of ore containing 221 million t of zinc and 97 million t of lead. Of these amounts, approximately 154 million t of zinc and 70 million t of lead are estimated to be recoverable. The analyses indicate that demonstrated resources in market economy coun- tries should be sufficient to satisfy projected demand for primary lead and zinc through the balance of the century. The U.S. lead industry will continue to have a comparative advantage over the rest of the world industry, barring any dras- tic increase in the cost of compliance with pollution control regulations. It appears that the comparative disadvantage faced by the U.S. zinc industry will probably intensify owing to the relative quantity of lower cost zinc resources in other countries, especially Canada, Australia, Mexico, and Peru. 1 Mineral economist. ' Mininc enjriDeer. * Economist. Minerals Availability Field Office, Bureau of Mines, Denver, CO. INTRODUCTION Rising production costs in combination with lag- ging demand and market prices for both lead and zinc have created serious economic problems for many lead and zinc producers worldwide. The purpose of this Bureau of Mines report is to evaluate the comparative costs of potential lead and zinc production from demon- strated resources of lead and zinc in the market economy countries. 4 This will provide an estimate of the costs (in constant January 1981 dollars) associated with potential supplies of primary lead and zinc, and illustrate the production potential of the United States compared with producers in other market economy countries. This study evaluates the potential availability of lead and zinc from 235 producing mines and unde- veloped deposits, with 186 mines and deposits evalu- ated as primary zinc operations ; 30 mines and deposits evaluated as primary lead operations; and 19 mines and deposits evaluated as primary copper operations. A complete listing of the 235 mines and deposits that were evaluated and their ownership is presented in the "Lead and Zinc Resources" section. The assignment of a particular commodity as the primary product, gen- erally based on that product providing the largest proportion of sales revenue at current (1981) market prices, was a necessary requirement of the evaluation process using a price determination model as described in the "Evaluation Methodology" section. Resource tonnage estimates for the lead and zinc mines and deposits evaluated for this report were made at the demonstrated resource level according to the mineral resource classification system (fig. 1) developed jointly by the Bureau and the U.S. Geologi- cal Surv ey (I). 5 It shou ld be kept in mind that re- ported demonstrated tonnage estimates for many lead 4 Market economy countries are defined as all countries that are not considered centrally planned economy countries. Centrally planned economy countries are Albania, Bulgaria, China, Cuba, Czechoslovakia, German Democratic Republic, Hungary, Kam- puchea, Laos, Mongolia, North Korea, Poland, Romania, U.S.S.R., and Vietnam. 6 Italic numbers in parentheses refer to items In the list of references preceding the appendix. and zinc deposits tend to be somewhat conservative. Many companies, particularly small ones, find it economically prohibitive to define resources beyond a 5- or 10-yr planning horizon. The procedure of this study was to quantify the recoverable demonstrated resource and the engineering and economic parameters affecting actual or proposed production from the mines and deposits selected for evaluation. The flow of the Minerals Availability Program (MAP) evaluation process from deposit identification to development of availability information is illus- trated in figure 2. This flowchart demonstrates the various evaluation stages required to estimate the potential availability of primary lead and zinc metal from demonstrated geologic resources. The following factors had to be estimated before the total production potential of lead and/ or zinc from each mine and deposit could be ascertained: 1. The approximate annual production potential of each mine or deposit over its life. 2. The total mine and mill capital and operating costs. 3. The cost of transporting concentrate from each mine to the appropriate smelter and the subsequent transportation from the smelter to the refinery if the refinery was at a separate location. 4. The estimated smelting and refining charges for each commodity using typical smelter schedules for each major producing country. Smelter schedules for smelting and refining in countries outside of North America, Western Europe, or Japan were estimated using the major regions as models. Although an effort was made to simulate the actual flows from the mines through the smelting and refining stage, the scope of this study prohibits an attempt to exactly match the capacities of existing smelters and refineries. For currently producing operations, the designed mining and milling capacities and other available pro- duction specifics were used in this study. For unde- veloped or developing deposits, appropriate mining and processing methods and potential capacities were based on published plans from mining companies or were Cumulative production IDENTIFIED RESOURCES Demonstrated UNDISCOVERED RESOURCES Probability range (or) MARGINALLY ECONOMIC SUBECONOMIC + + Other occurrences Includes nonconventional and low-grade materials Figure 1. — Classification of mineral resources. ■rtd i M -ierai t | ln(fosir. Domestic deposits were evaluated by personnel of the Bureau's Field Opera- tions Centers and foreign data collection and cost estimation were performed under contract by Pincock, Allen & Holt. Inc.. Tucson, AZ; personnel of the Bureau's Minerals Availability Field Office, Denver, CO, evaluated the data and performed the economic evaluation analyses. The following objectives served as guidelines pursuant to the conduct of this study: 1. To determine the demonstrated resources of lead and zinc metal from all known significant deposits in market economy countries. Estimates of identified re- sources for lead and zinc are also mentioned ; however, in the availability analyses, only demonstrated re- sources are included. 2. To evaluate the quantity and the average total costs of potential primary lead and zinc production from resources in market economy countries in rela- tion to physical, technological, political, and other factors that affect production from each mine or deposit. 3. To aggregate and illustrate graphically total potential production of primary lead and zinc at the average total cost of each mining operation, including a 15-pct discounted-cash-fiow rate of return (DCF- ROR) on all investments. WORLD LEAD AND ZINC INDUSTRIES Although lead and zinc exhibit a geologic affinity for each other, their respective industries are distinct- ly different, each with its unique problems and pros- pects. The following sections are largely extracted from the 1983 Bureau of Mines Mineral Commodity Profiles for lead (3) and zinc U). LEAD INDUSTRY Lead was mined in about 50 countries during 1981, but smelted to produce primary metal in only 35. There were 55 countries refining secondary lead. The United States continued to be the leading producer of both primary and secondary lead with production of 438.000 t of primary and 641,000 t of secondary lead in 1981. In primary refined lead production, the U.S.S.R. ranked second with an estimated 410,000 t, followed by Japan with 230,000 t, France with 210,000 t, and Australia with 208,000 t. The U.S.S.R. also ranked second in secondary lead production with an estimated 220,000 t in 1981, followed by the United Kingdom with 198,000 t, the Federal Republic of Germany with 158,000 t, and Italy with 92,000 t. World mine produc- tion, by country, for 1961, 1971, and 1981 is shown in table 1, and a comparison of world smelter and refinery production, by region, of primary and secondary lead for 1981 is shown in table 2. World mine production of contained lead in 1981 amounted to 3.3 million t, which was only 64 pet of the total world demand. The United States had the greatest production, followed by the U.S.S.R., Aus- tralia, Canada, and Peru. Eleven countries, producing over 100,000 t each, accounted for 76 pet of the total world mine production. Approximately 350 mines in the world produced lead in 1981, in most cases as a coproduct or byproduct of other metals. Lead in the United States is produced from about Table 1.— World lead mine production, 1961, 1971, and 1981, metric tons of contained lead Area and country 1961 1971 1981' Area and country 1961 1971 1981' North America: Canada 165,616 392,970 332,100 United States 237,61 5 524,861 445,500 Latin America: Argentina 27,760 39,889 32,000 Bolivia 20,301 23,125 16,700 Brazil 13,608 27,837 29,600 Chile 2,043 881 500 Colombia 655 205 100 Ecuador 111 200 Guatamala 8,580 500 100 Honduras 6,134 17,967 14,000 Mexico 181,326 156,852 157,400 Nicaragua 575 Peru 136,400 165,816 186,700 Europe: Austria 5,489 7,715 4,200 Bulgaria 79,834 99,792 116,000 Czechoslovakia 6,532 5,806 3,400 Finland 3,120 4,739 1,600 France 18,901 29,771 19,000 German Democratic Rep 6,895 9,979 Germany, Fed. Rep. of 49,577 41 ,102 21 ,600 Greece 11,600 10,469 21,000 Greenland 9,166 30,000 Hungary 1,733 1,000 Ireland 253 51,592 29,900 Italy 47,719 31,600 20,600 Norway 2,290 3,063 3,600 Poland 38,200 62,778 50,400 Portugal 25 1,383 Romania 11,975 38,102 33,500 Spain 79,709 70,151 83,000 Europe — Continued Sweden U.S.S.R United Kingdom Yugoslavia Africa: Algeria Congo (Brazzaville). . Egypt Morocco Namibia Nigeria South Africa, Rep. of Tanzania Tunisia Zambia Asia: Burma China India Indonesia Iran Japan Korea, North Korea, Rep. of Pakistan Philippines Thailand Turkey Oceania: Australia New Zealand 62,143 353,808 1,501 96,682 9,200 875 36 88,270 63,504 6 93 351 16,963 15,382 16,800 1 90,000 4,062 14,969 46,281 50,000 920 101 2,211 1,089 273,992 79,455 453,600 1,497 124,349 4,717 29 78,001 71,499 215 18,870 27,670 8,999 1 100,000 1,556 200 24,041 70,587 80,000 16,544 6 1,473 5,967 403,562 1,246 Grand total 2,381 ,381 3,395,607 84,100 410,000 2,400 120,000 2,600 3,500 115,974 59,100 1,000 98,900 8,000 14,000 15,600 155,000 15,300 10,000 45,900 100,000 11,400 1,100 17,000 8,000 392,300 3,344,855 1 Estimated. NOTE. — Data may not add to totals shown because of independent rounding. Table 2. — World primary and secondary lead production In 1981, thousand metric tons of contained lead Mine Smelter Refinery Secondary (refined) North America: United States. . . 445.5 495.3 495.3 641.1 Canada 332.1 168.5 168.5 69.7 Latin America 437.3 300.7 294.4 99.1 Europe 1,055.3 1,221.7 1,454.6 1,033.2 Africa 312.1 118.5 118.5 30.1 Asia 378.0 487.1 477.2 162.9 Oceania 392.3 367.2 207.7 44.5 Total 3,352.6 3,159.0 3,216.2 2,080.6 40 individual mines in 18 States. Lead concentrates are reduced to lead bullion at five smelters located in Missouri, Montana, and Texas. Three smelters in Mis- souri also have refineries, and there is one additional refinery in Nebraska that processes crude bullion from smelters in Montana and Texas. The Bunker Hill smelter-refinery in Bradley, ID, shut down indefinite- ly in 1981 as a result of unfavorable economic con- ditions. In 1981, the St. Joe Lead Co. operated six mines and four mills in southeast Missouri and a lead smelter at Herculaneum, MO; AMAX Lead Co. of Missouri operated a mine-mill-smeiter complex at Boss, MO, jointly owned by AMAX and Homestake Mining Co. ASARCO Incorporated operated mines in Colorado and New Mexico, smelters in El Paso, TX, East Helena, MT, and Glover, MO, and a lead refinery in Omaha, NE. The three ASARCO smelters and the Bunker Hill smelter treated both domestic and im- ported concentrates, whereas Missouri facilities norm- ally process domestic concentrates, mostly from Mis- souri. Other companies operating lead and lead-zinc mines included the Ozark Lead Co., a subsidiary of Kennecott Corp.; Hecla Mining Co.; and Cominco American Inc. Consumption Approximately 5.2 million t of lead in all forms was consumed worldwide in 1981, with the United States being the dominant consumer, accounting for 22 pet of total consumption. The U.S. consumption share of refined lead and lead in antimonial lead (excluding other lead alloys and remelt) from 1978 to 1981 averaged 31 pet of the total, compared with 40 pet for Europe and 9 pet for Japan. Actual consump- tion for individual centrally planned economy coun- tries is not available but, overall, their consumption is estimated to be about 23 pet of the world's total for all types of lead metal ; slightly greater than the 1981 percentage for the United States. Trade Patterns World trade from 1976 through 1981 averaged 1.9 million t of lead per year contained in the form of ores and concentrates (35 pet), bullion (14 pet), and refined metal (51 pet). The figures exclude internal trade between the centrally planned economy coun- tries, but include estimates of trade between these countries and the market economy countries. During this period, Canada was the leader in exports of con- centrates, averaging 144,000 t/yr and Peru was second with 90,000 t yr. Japan and the Federal Republic of Germany were the leading importers of concentrates during the 1976-81 period. Japan's imports were pri- marily from Canada and Peru, and concentrate imports for the Federal Republic of Germany were from Sweden, Canada, Ireland, and Morocco. France, the third leading importer of lead concentrates, also de- pended heavily on Morocco, Ireland, and the Republic of South Africa. In 1981, Canada and Peru supplied 64 pet cf the 59,000 t of concentrates imported by the United Stat The leading exporters of refined lead from 1976 through 1981 were Australia with 156.000 t/yr, Canada with 123.600 t yr, and Mexico with 101.000 t yr. These three countries exported 40 pet of the world total lead exports over the 6-yr period and, in 1981. provided 94 pet of the U.S. import total of 100,000 t of refined metal. The United States was the largest importer of lead metal during this period, averaging 159,500 t/yr, followed by Italy with an average of 148,000 t/yr. Italy depends primarily on the Federal Republic of Germany, Morocco, Australia, Namibia, and Mexico for refined metal. Although the United States is a significant importer of refined metal, imports do not constitute a major component of U.S. total supply. In 1981, the foreign component of U.S. total supply was about 4 pet in lead concentrates and 7 pet in refined metal. Domestic ores contributed about 31 pet to U.S. supply and recycled old scrap contributed about 40 pet. Industry stocks made up the remaining 18 pet. There have been no shipments of lead from the National Defense Stockpile since 1976. The U.S. import, export, and consumption levels for various forms of lead in 1980 and 1981 are shown in table 3. Secondary Sources Secondary lead is recovered from scrap, product and chemical industry wastes, lead refinery drosses, and other metallurgical wastes such as mattes, dust, slag, and residues. Most secondary lead is derived from wornout. damaged, or obsolete fabricated products such as battery plates and oxides, cable covering, pipe, and sheet. Such material is collected, smelted, and re- fined in secondary smelters to produce soft lead and antimonial lead or other various lead-base alloys. Additional secondary lead is recovered from process scrap, largely drosses and residues generated during the fabrication of lead products and recycled to sec- ondary smelters for production of refined ' ad. Some secondary lead materials are reused after remelting without refining, but an increasing * oportion is processed in refineries because of the need, in most uses, to meet customer product specifications. Second- ary materials have been the source for over 35 pet of the total world use of lead and for over 50 pet of U.S. requirements in recent years. The main source of secondary lead is automobile storage batteries that have been scrapped after use. In the United States and other industrialized countries, about 90 pet of the lead 81,300 100,108 2,868 950 2,661 474 3,818 115,029 3,135 130,898 Table 3.— U.S. lead Import, export, and consumption for 1980-81, metric tons of contained lead 1980 1981 IMPORT Ore, Hue dust, base bullion, and residues: Argentina 61 3,932 Canada 3,232 1 ,972 Chile 2,236 2,084 Honduras 3,973 11,617 Peru 18,141 6,299 Other 2,268 1,751 Total 29,911 27,655 Metal (pigs and bars): Australia 10,844 9,080 Canada 34,929 50,849 Mexico 28,657 33,723 Peru 3,298 2,907 Other 3,532 3,549 Total Reclaimed scrap Sheets, pipe, shot Total Total imports EXPORT Ore and concentrates 27,615 33,043 Blocks, pig, anodes, etc.: Unwrought 147,356 14,484 Unwrought alloys 9, 1 44 2,320 Wrought lead and lead alloys > 7,958 6,516 Scrap' 71,791 35,651 Total 263,863 92,014 CONSUMPTION ====== Apparent consumption 997,000 1 ,040,000 ' Lead content at 60 pet. NOTE. — Data may not add to totals shown because of independent rounding. used in the manufacture of storage batteries is re- cycled. ZINC INDUSTRY Changes in world mine and smelter production of zinc have led to changes in the zinc supply pattern of the United States, particularly during the last decade. The result has been an increasing reliance on foreign sources of zinc metal to satisfy domestic requirements. World zinc mine production for 1961, 1971, and 1981 are shown in table 4. The United States, which was the largest zinc metal producer in the world from 1901 through 1971, has been dependent upon imports of concentrates for a substantial portion of smelter feed since the begin- ning of World War II. Domestic primary production of slab zinc reached a peak of 944,014 t in 1969, with a continuous decline in production since that time as 10 domestic primary zinc smelters have been closed and only 2 new smelters were commissioned, 1 in 1976 and 1 in 1978. Zinc oxide production from zinc fuming plants at the El Paso, East Helena, and Bunker Hill lead smelters has also been curtailed with the fuming furnaces at all three plants on temporary or indefinite closure. Because of this reduction in U.S. smelting capacity, the need for foreign concentrates has de- clined significantly, with imported refined zinc metal becoming a major factor in U.S. supply. World zinc metal production increased from about 1 million t/yr in the middle 1930's to 6.1 million t in Table 4. — World zinc mine production, 1961, 1971, and 1981, metric tons of contained zinc Area and country 1961 1971 198V Area and country 1961 1971 1981' North America: Canada United States Latin America: Argentina Bolivia Brazil Chile Colombia Ecuador Guatamala Honduras Mexico Nicaragua Peru Europe: Austria Bulgaria Czechoslovakia Finland France German Democratic Rep. Germany, Fed. Rep. of . . Greece Greenland Hungary Ireland Italy. . P Norway Poland Portugal Romania 401,979 421,295 30,210 5,333 162 726 7,926 6,215 266,973 173,872 6,034 73,937 ( 2 ) 46,597 15,600 6,985 87,213 17,547 7,983 167 134,224 9,331 139,579 ( 2 ) 1,267,582 455,907 43,864 45,077 16,920 1,982 112 126 506 22,894 264,972 4,056 318,078 21 ,073 79,834 8,564 50,888 15,140 9,979 131,986 14,210 4,808 87,545 105,870 10,717 193,596 2,046 39,826 1,097,200 312,400 30,000 47,000 103,000 1,100 100 1,600 500 18,000 211,600 496,700 18,200 90,000 7,200 53,600 37,400 91,800 26,800 86,400 2,000 120,300 41,500 31 ,000 146,500 55,000 Europe — Continued Spain Sweden U.S.S.R United Kingdom Yugoslavia Africa: Algeria Congo (Brazzaville). . Morocco Namibia Nigeria South Africa, Rep. of Tunisia Zaire Zambia Asia: Burma China India Iran Japan Korea, North Korea, Rep. of Philippines Thailand Turkey Vietnam Oceania: Australia New Zealand 87,983 75,201 399,168 59,883 42,638 40,780 13,522 3,396 99,634 45,433 7,348 '100,000 5,080 13,517 168,262 '80,000 450 3,313 898 2,000 292,840 87,541 99,044 650,462 98,695 15,797 633 12,338 43,697 158 1 1 ,794 109,227 57,067 4,003 '100,000 8,246 58,061 294,424 '135,000 28,161 3,375 18,933 452,654 1,969 Grand total 3,420,144 5,515,200 180,000 180,900 790,000 9,600 117,900 6,200 3,000 7,900 29,600 100 87,172 7,500 63,300 22,200 4,500 160,000 31 ,600 15,000 242,042 140,000 56,500 5,289 30,721 6,000 508,400 100 5,832,424 ' Estimated. 2 Production data not available; estimates are included in total. NOTE. — Data may not add to totals shown because of independent rounding. 1981. The leading metal producing countries in 1981 were the U.S.S.R., Japan, Canada, the United States, Federal Republic of Germany, and Australia. Over the past 10 yr, Brazil, Peru, Canada, U.S.S.R., Mexico, Republic of Korea, India, and Netherlands increased metal production considerably, whereas production in the United States, Zambia, and Zaire declined. About one-half of the world's mine capacity in market economy countries is held by seven companies either through direct ownership, subsidiaries, or equity sharing. These companies are Noranda Mines Ltd., Cominco Ltd., and Kidd Creek Mines Ltd. (Canada) ; ASARCO Incorporated (United States) ; The Rio Tinto Zinc Corp. Ltd. (United Kingdom) ; Centromin (Peru) ; and Societe Generate de Belgique (Belgium). The largest zinc refining companies are Societe Generale de Belgique, The Rio Tinto Zinc Corp. Ltd., and Mitsui Mining & Smelting Co. Ltd. (Japan). Several large, vertically integrated firms with mines, smelters, and refineries are prominent in the U.S. primary zinc industry. The principal companies that operated both mines and smelters or refineries in 1981 were Amax Zinc Co. Inc, ASARCO Incorporated, The Bunker Hill Co., Jersey Miniere Zinc Co., and St. Joe Resources Co. In 1981, these companies accounted for 86 pet of the primary slab zinc produced in the United States and 58 pet of the mine output. Cominco American Inc., The New Jersey Zinc Co., Ozark Lead Co., Hecla Mining Co., and United States Steel Corp. were other major mine producers in 1981, accounting for an additional 40 pet. The Bunker Hill complex closed indefinitely in December 1981 and has not re- opened. A number of zinc-producing mines closed in late 1981, 1982, and 1983 for economic reasons. Consumption World consumption of refined metallic zinc has grown more or less steadily over the past 50 yr. Slab zinc consumption in market economy countries at- tained its highest level, 4.9 million t in 1973, but has fluctuated below that level since that time. Consump- tion in 1982 was about 4.2 million t. The anemic state of the world economy, the introduction of thin-wall diecasting, weight-reduction programs in the auto- mobile industry, and substitution by alternate ma- terials, have adversely affected zinc consumption in recent years. Europe traditionally is the largest zinc-consuming area and, in 1981, accounted for about 36 pet of world consumption, followed by North America, 31 pet, and Asia, 26 pet. The United States has historically been the largest single consumer of zinc; however, its pro- portion of world consumption has declined. Of the total refined zinc metal consumed by market economy countries in 1981, the United States consumed 16 pet compared with 32 pet in 1960. On the other hand, Japan, because of its rapid industrial growth over the last two decades, was the second largest consumer of zinc in 1981, having increased its proportion of world consumption from 8 pet in 1960 to 12 pet in 1981. In general, the growth of zinc consumption has been more rapid in the newly industrializing countries, especially in Asia, than in the older industrialized countries. Trade Patterns Although the trend towards vertical integration in zinc mining countries has continued over the past decade, world trade in zinc concentrates continues to be large and in 1981 was estimated to be 1.9 million t. Concentrates are mainly exported by Canada, Peru, Australia, Sweden, and Ireland; importing countries are mainly Japan, the United States, and countries in Western Europe. Domestic imports of concentrate de- creased significantly in the early 1970's owing to numerous smelter closures. Imports of zinc in concen- trate by domestic smelters averaged 380,000 t/yr dur- ing the 1960-71 period, but have averaged only 160,000 . through 1982. During 1981. world trade in slab zinc was esti- mated to be 1.7 million t. or about 30 pet of world refined zinc production. The largest slab zinc exporters were Canada, Australia. Belgium, Netherlands, Fin- land, and Federal Republic of Germany. Peru and Mexico have opened new smelters since 1980, and slab zinc exports from these countries are expected to increase substantially. The largest importers of slab zinc in 1981 were the United States, Federal Republic of Germany. United Kingdom, India, and France. The United States imports more than one-half of the zinc it consumes and typically has an import de- pendence exceeding 60 pet. Approximately 60 pet of the concentrate and metal imports are obtained from Canada and Mexico, and therefore, severe supply dis- ruption is not likely to occur. Canada has the world's largest zinc mine production and has the capacity to meet essentially the whole of U.S. import require- ments. A number of other countries, principally Peru, Spain, and Australia, supply the remainder of U.S. zinc imports. The U.S. import, export, and consumption levels for various forms of zinc in 1980 and 1981 are shown in table 5. Secondary Sources Recovery of zinc from old scrap, mainly in the form of diecastings, engravers plate, and brass and Table 5.— U.S. zinc Import, export, and consumption for 1980-81, thousand metric tons of contained zinc 1980 1981 IMPORT Ore and concentrates: Canada 110 180 Honduras 7 4 Mexico 14 21 Peru 40 29 Other 1J ]2__ Total 182 246 Metal (blocks, pigs and slabs): Australia 25 26 Canada 280 309 Finland 18 29 Mexico 24 15 Peru 4 43 Spain 11 29 Zaire NAp 29 Other 48 132 Total Total imports EXPORT Waste and scrap Ore and concentrates Total CONSUMPTION Apparent consumption Slab 811 841 Ores 59 61 Zinc scrap 133 149 Other scrap 1 139 139 Total 1,142 1,189 NAp Not applicable. ' Includes zinc contained in copper-, aluminum-, and magnesia-based scrap. NOTE. — Data may not add to totals shown because ol independent rounding. bronze currently represents from 6 to 8 pet of the total world supply. New scrap is principally zinc- and copper-base alloys from manufacturing operations and drosses and skimmings from galvanizing and diecasting operations. New scrap is either sold to smelters or processed as runaround scrap by the com- pany that generates it. The large use of zinc in gal- vanizing and in compounds in which the zinc is lost limits the potential for any increased recycling of old scrap. 410 ' 592 612 858 30 54 30 54 84 84 EVALUATION METHODOLOGY To determine the potential availability of lead and zinc, 235 mines and deposits in market economy countries were evaluated: 186 mines and deposits were evaluated with zinc as the primary commodity; 30 mines and deposits were evaluated with lead as the primary commodity, and 19 mines and deposits were evaluated with copper as the primary commodity. Geologic and operating data were collected for each of the evaluated mines and deposits. These data included demonstrated and identified resource estimates, actual or estimated mine and mill operating capacities in- cluding future expansions and development plans when ted. estimated mine life based 00 production capacity and demonstrated resource, all capital and reinvestment co I ating costs for mining and milling, mass balances for each concentrate produced in the mill, and estimates of smelting and refining toll charges for each concentrate and the pay-fors (credits and deductions) associated with each com- modity treated. Although an effort was made to simulate the ac- tual flows from the mines through the smelting and refining stage, with the appropriate smelter charges and pay-fore associated with the particular smelter and refinery; the scope of this study does not attempt to exactly matrh the capacities of existing smelters and refineries. Smelting and refining charges and the pay-for schedules used in the study are for typical smelters and refineries within the particular region or country. For f-xample, one smelter schedule was used for all concentrates sent to the United States, another was used for all concentrates sent to Japan, and so forth. For undeveloped deposits, future materials flows were estimated based on historical patterns, and on estimates of where plants for future smelting and refining capacity is likely to be constructed. For each mine and deposit included in this evaluation, capital expenditures were estimated for exploration, acquisition, development, mine plant and equipment, and mill plant and equipment. The capital expenditures for mining and processing facilities in- clude the costs of stationary and mobile equipment, construction, engineering fees, infrastructure, and working capital. Infrastructure includes costs for access and haulage facilities, ports, water facilities, power supply, and personnel accommodations. Work- ing capital is a revolving cash fund required for cur- rent operating expenses such as labor, supplies, in- surance, and taxes. The total operating cost is a combination of direct and indirect costs. Direct operating costs include materials, utilities, direct and maintenance labor, and payroll overhead. Indirect operating costs include technical and clerical labor, administrative costs, facilities maintenance and supplies, and research. Other costs in the analysis are fixed charges, including local taxes, insurance, depreciation, deferred expenses, interest payments (if any), and return on investment. After production parameters and cost estimates were established for each mine and deposit, all of the operating data were entered into the supply analysis model (SAM). The Bureau developed the SAM (5) to perform discounted-cash-flow rate of return (DCF- ROR) analyses to determine the long-run constant dollar price at which the primary commodity must be sold (f.o.b. the smelter-refinery) to recover all costs of production including a prespecified DCFROR on all investments. The DCFROR is most commonly defined as the rate of return that makes the present worth of cash flow from an investment equal the present worth of all aftertax investments (6). For this study, a 15-pct DCFROR was considered the necessary rate of return to provide the incentive to develop a mineral property or to continue producing over the long run. The determined value for the pri- mary commodity price is equivalent to the average total cost of production for the operation over its pro- ducing life under the set of assumptions and conditions (e.g., mine plan, full capacity production, and a market for all output) necessary to make a full economic evaluation. If an operation has more than one product, the prices of the byproducts are assumed to be the market prices for the period of analysis, which for this study was January 1981. An exception was made for the byproduct prices for cobalt, gold, and silver, which were adjusted to reflect more representative prices over the past 3-yr period. The January 1981 prices for Table 6.— Byproduct prices used in the economic evaluations, January 1981 dollars Commodity and unit Pnce Barite st. . $65.00 Cadmium lb . . 2.50 Cobalt lb. . '7.00 Copper lb . . .89 Fluorspar t. . 140.00 Germanium kg . . 1 ,060.00 Gold tr oz. . '425.00 Iron (pellets) It units . . .81 Lead lb.. -34 Manganese It units . . 1 - 70 Silver tr oz. . l10 -00 Sulfur t . . 1 1 7 - 50 Tin lb.. 74 9 Tungsten lb. . 14 - 7 ° Zinc lb.. 41 1 Adjusted to reflect representative period average; January 1981 price was anomalously high. these three commodities were anomalously high. Revenues generated by byproducts are credited against the cost of production. The market prices for by- products used in the analysis are shown in table 6. The SAM system contains a separate tax records file for each particular State or nation, which includes all of the relevant tax parameters under which a min- ing firm would operate, such as corporate income taxes, property taxes, royalties, severance taxes, or other taxes that pertain to the production of lead or zinc. These tax parameters are applied against each mineral deposit under evaluation with the implicit assumption that each deposit represents a separate corporate en- tity. Other charges considered in the analysis include standard deductibles such as depreciation, depletion, deferred expenses, investment tax credits, and tax-loss carryforwards. The system also contains an additional file of economic indexes to allow for continuous updat- ing of cost estimates to a base date. The recently published Bureau of Mines report on the availability of lead and zinc — domestic (7), used 1981 cost esti- mate data updated to the base study date of January 1982. This study uses the base date of January 1981 since the data were collected for that year and it was felt that the limited cost-index data for certain coun- tries were too unreliable to update to January 1982. For this reason, the U.S. costs presented in this report differ slightly from those presented in the domestic lead and zinc report. Detailed cash-flow analyses are generated by the SAM system for each preproduction year of an opera- tion beginning with the initial year of the analysis, 1981. Upon completion of the individual analysis for each mine and deposit, all properties were simultane- ously analyzed and aggregated onto the availability curves presented in the "Availability of Lead and Zinc" section of this report. LEAD AND ZINC RESOURCES Demonstrated lead-zinc resources of the 235 mines and deposits evaluated in market economy countries in 1981 were approximately 4.3 billion t of ore containing 221 million t of zinc and 97 million t of lead. Of these amounts, approximately 153.7 million t of zinc and 70.4 million t of lead are estimated to be recoverable. At the identified resource level, approxi- mately 250 million t of zinc and 111 million t of lead are contained in 5.3 billion t of lead and zinc ores in market economy countries. An additional 24 million t of zinc and 33 million t of lead are contained as identi- fied resources in centrally planned economy countries. Demonstrated lead-zinc resources, by country, are shown in table 7. Percentage shares of contained lead, by country, are shown in figure 3, and percentage shares of contained zinc are shown in figure 4. Note Table 7. — Summary of demonstrated lead and zinc resource values in market economy countries, as of January 1981 Mines- Resources Country deposits (ore). 10 3 1 A:e-a 1 3.580 Argentina 1 6.600 Australia 15 468.588 Austna 1 10,000 Bolivia ... 2 2.365 Brazil ... 2 23.237 Bur-na 1 3.100 Canada 42 760.880 Finland . . 4 40,950 France 5 16,816 Germany. Fed. Rep ol 3 24.400 Greece 2 20,000 Greenland 1 3,738 Honduras ... 1 7.200 India 4 110,200 Ireland 5 59.506 Italy 5 32,900 Japan 9 74.579 Mexico 18 237.638 Morocco 6 24,230 Namibia 3 14,798 Norway 1 12,050 Peru .... 15 254.996 Portugal 1 140.000 Soutn Africa. Rep of 3 282.433 Spain 6 194.260 Sweden 5 65,900 Turkey 3 33,358 Zaire 1 49.550 Zambia 1 1.741 Total or average 167 2,979,592 United States 68 1.354.892 Grand total c average 235 4.334,484 NOTE —Data may not add to totals shown because of independent rounding. Weighted av grade, pet Contained metal. 10 3 1 Zinc Lead Zinc Lead 5.56 1.33 199 48 7.60 6.20 502 409 9.01 495 42,247 23.207 4.80 1.40 480 140 9.05 1.34 214 32 8.43 1,12 1,960 261 5.00 6.25 155 194 6.34 2.27 48.258 17,308 2.72 .08 ' 1,113 31 5.11 2.15 860 362 8.97 246 2,191 588 4.50 350 900 700 13.40 4.40 501 165 8.00 4.20 576 302 499 1.97 5,499 2,168 897 2.04 5,339 1,216 4.52 1.44 1,487 475 4.77 .86 3,561 641 3.52 1.83 8,380 4,359 .61 689 150 1,670 2.89 3.20 429 473 1.20 .00 145 3.44 1.13 8,765 2,881 3.24 1.23 4,536 1,722 4.51 1.87 12,741 5,287 2,89 1 24 5,622 2,414 3.91 336 2,579 2,215 4.76 12 1,588 40 13.60 .00 6,739 22.30 11.30 388 197 564 3.91 2.33 201 5 10 2.22 168,101 52,949 221,050 69,515 27,254 96,769 Figure 3. — Percent share economy countries. of contained lead in market Figure 4. — Percent share of contained zinc in market economy countries. 10 that the weighted* average ore grades include both primary and byproduct ore grades. Average zinc grades from mines and deposits evaluated as primary zinc operations are higher than the averages shown in table 7, as are the average lead grades from mines and deposits evaluated as primary lead mines. A more meaningful comparison of lead and zinc grades can be shown by presenting minable ore tonnages (recover- able ore) and actual feed grades (including dilution) for mines and deposits evaluated as primary zinc, lead, or copper operations. These data, by country, are presented in tables 8 through 13. Table 8. — Summary of January 1981 minable resource values for mines and deposits evaluated as lead properties, with minable resources and weighted-average feed grades r Mines- Resources, Grade, Contained country deposits 10 3 t pet. lead, 10 3 t Australia 1 5,950 12.60 750 Canada 1 838 4.76 40 France 1 7,389 2.54 188 Mexico 2 7,914 6.65 447 Morocco 5 22,363 6.87 1 ,537 Namibia 1 6,300 6.98 440 South Africa, Rep. of .. . 2 121,075 3.71 4,494 Spain 1 1 ,830 5.00 92 Sweden 2 34,930 4.18 1,459 Total or average 16 208,589 4.53 9,445 United States 14 337,108 5.62 18,931 Grand total or av. . . 30 545,697 5.19 28,375 1- NOTE. — Data may not add to totals shown because of independent rounding. Table 9. — Summary of January 1981 minable resource values for mines and deposits evaluated as lead properties, with minable resources and weighted-average grades for byproduct zinc _ . Mines- Resources, Grade, Contained ™ deposits 10 3 t pet zinc, 10 3 t Australia 1 5,950 9.70 577 France 1 7,389 .59 44 Mexico 1 4,701 3.70 174 Morocco 2 3,430 1 .46 51 Namibia 1 6,300 1 .90 120 South Africa, Rep. of .. . 2 121,075 1.24 1,498 Sweden 1 32,000 .74 237 Total or average 9 180,845 149 2,700 United States 12 332,793 1.05 3,504 Grand total or av. . . 21 513,638 1.21 6,204 NOTE. — Data may not add to totals shown because of independent rounding. Table 10.— Summary of January 1981 minable resource values for mines and deposits evaluated as zinc properties, with minable resources and weighted-average feed grades Country Mines- deposits Resources 10 3 t Grade, pet Contained zinc, 10 3 1 Country Mines- Resources, Grade, Contained deposits 10 3 t pet zinc, 10 3 t 5 32,900 4.05 1,334 8 62,560 4.21 2,636 16 220,938 3.29 7,263 1 1,500 5.85 88 1 5,078 6.30 320 14 100,401 6.78 6,808 1 103,451 3.06 3,166 1 143,570 6.04 8,672 5 173,676 2.75 4,775 2 25,288 7.50 1.898 1 698 24.50 171 1 32,550 12.20 3,971 1 2,067 17.80 368 132 2,232,296 6.02 134,494 54 1 ,024,463 4.43 45,441 186 3,256,759 5.52 179,935 Algeria 1 3,381 5.00 169 Argentina 1 6,967 6.84 477 Australia 12 404,970 9.10 36,858 Austria 1 10,000 3.80 380 Bolivia 2 3,621 5.14 186 Brazil 2 23,237 7.84 1 ,823 Burma 1 3,100 4.00 124 Canada 33 612,288 6.30 38,609 Finland 2 28,523 2.68 765 France 4 10,060 6.43 647 Germany, Fed. Rep. of. . . 3 24,963 8.45 2,109 Greece 2 20,000 4.05 810 Greenland 1 3,177 13.40 426 Honduras 1 7,200 7.20 518 India 4 111 ,629 4.30 4,803 Ireland 5 54,503 7.92 4,322 Italy Japan Mexico Morocco Namibia Peru Portugal South Africa, Rep. of . Spain Sweden Turkey Zaire Zambia Total or average . . . United States Grand total or av . NOTE. — Data may not add to totals shown because of independent rounding. Table 11. — Summary of January 1981 minable resource values for mines and deposits evaluated as zinc properties, with minable resources and weighted-average grades for byproduct lead Country Mines- deposits Resources, 10 3 t Grade, pet Contained lead, 10 3 t Country Mines- Resources, deposits 10 3 t Grade, pet Contained lead, 10 3 t Algeria Argentina Australia Austria Bolivia Brazil Burma Canada Finland France Germany, Fed. Rep. of. Greece Greenland Honduras India Ireland 1 1 11 1 2 1 1 26 1 4 3 2 1 1 4 5 3,381 6,967 402,405 10,000 3,621 17,613 3,100 540,894 11,180 10,060 24,963 20,000 3,177 7,200 1 1 1 ,629 54,503 1.20 5.58 5.03 1.10 .66 1.26 5.00 2.84 .26 .99 2.27 '3.15 4.40 3.80 1.75 1.80 41 389 20,223 110 24 222 155 15,361 29 100 567 630 140 274 1,951 983 Italy Japan Mexico Morocco Namibia Peru Portugal South Africa, Rep. of. Spain Sweden Turkey Zambia Total or average United States Grand total or av 5 8 15 1 1 14 1 1 5 2 1 1 120 20 140 32,900 62,560 220,136 1,500 5,078 100,401 103,451 143,570 173,676 25,288 698 2,067 2,102,018 354,390 2,456,409 1.31 .74 1.52 1.35 1.80 2.77 1.16 .47 1.13 1.58 1.20 9.00 2.51 1.78 2.40 432 464 3,352 20 91 2,777 1,200 675 1,959 399 8 186 52,762 6,295 59,057 NOTE. — Data may not add to totals shown because of independent rounding. A detailed breakdown of recoverable metal from lead and zinc resources is presented in the "Availa- bility of Lead and Zinc" section. Mines and deposits evaluated for this study, including ownership, status, and type, are listed in tables 14 through 16. Table 12. — Summary of January 1981 minable resource values for mines and deposits evaluated as copper properties, with minable resources and weighted-average grades for byproduct lead Country Australia Canaaa Japan Namibia Total or average Mmes- deposits Resources. 10 3 t Grade, pet Contained lead. 10 3 1 30.041 1.18 91.240 18 31.787 86 4.200 2.14 355 164 273 90 157.268 56 882 11 Table 13. — Summary of January 1981 minable resource values for mines and deposits evaluated as copper properties, with minable resources and weighted-average grades for byproduct zinc Mines- Resources. Grade. Contained deposits 10 3 t pet zinc, 10 3 1 Australia 2 7 30.041 145,228 3.32 3.94 997 Canada 5,727 Rnland 2 8.712 1.05 92 Japan 31,787 3.22 1.024 Norway 10.145 1.10 112 Peru 156.695 1.05 1.645 South Africa. Rep of 7,749 2.07 160 Sweden 7.600 2.88 219 Turkey erage . 2 31.200 3.11 969 Total or av 18 429.156 2.55 10.944 NOTE —Data may not add to totals shown because of independent rounding Table 14. — Mines and deposits evaluated as lead operations (Property information as of January 1981) Ownership Status' Type 2 Est ore capacity. 10 3 tyr Mining methods 102 Cut and fill. 168 Do. 136 Room and pillar 1,134 Do. 1.932 Do 1.134 Do. 2.058 Do. 200 Do 590 Do 952 Do. 1.769 Do. 867 Do. 454 Do. 212 Combined methods. 500 Do. 164 Room and pillar. 616 Do. 355 Combined methods. 235 Cut and fill. 150 Combined methods 200 Do. 84 Overhand. 400 Room and pillar 1,200 Open pit. 450 Cut and fill. 3.440 Do 1.800 Do 145 Do 1.500 Room and pillar. 300 Do. UNITED STATES Colorado Bulldog Homestake Mining Idaho: Lucky Friday Hecla Mining Co Missoun Boss-Bixby Getty Oil-AZCON-Hanna Mining Bnjshy Creek Division St Joe Minerals Corp Buick AMAX Lead-Homestake Lead Fletcher Division St Joe Minerals Corp Frank R Milhken Kennecott (Ozark Lead Co.) . . Higdon-BonneTerre Bunker Hill-St. Joe Minerals Indian Creek St. Joe Minerals Corp Magmont Cominco American-Dresser Viburnum No 28 and No 29 St Joe Minerals Corp Viburnum No 35 do West Fork ASARCO Ulan Ontario United Park City-Noranda FOREIGN Australia North Broken Hill North Broken Hill Ltd Canada: Yava Barymin Exploration Ltd France L Argentiere Penarroya Mexico: La Encantada La Encantada S.A Rosano Industria Minera Mexico S.A Morocco Aouli-MibJaden Penarroya Dieted Aouam BRPM-Royal Astunenne-Vielle 3 z ^ac~e- BRPM-Armico Royal Asturienne des Mines . . . ZeKla SODIM-ZELLIDJA-BRPM Namibia Tsumeto Tsumeb Corp. Ltd Soutn Afnca. Rep of Black Mountain Phelps Dodge-GFSA Broker Hi do jnares (El Cobrei Cia Minera la Cruz Sweden Bohden Metal AB Vassbo-GuttusjO do P P E P P P P PP P P P D D T P P P P D P P D P P P E P P P P 1 D— developing deposit. E — explored deposit. P — producing mine. PP- 1 C — surface and underground. S — surface. U — underground. ■past producer, T — temporarily shut down 12 Table 15. — Mines and deposits evaluated as zinc operations (Property information as of January 1981) Ownership Status' Type 2 Est ore capacity, 10 3 t/yr Mining methods 2,640 Open pit. 240 Cut and fill. 900 Open pit. 900 Do. 189 Room and pillar 381 Sublevel open stope. 272 Shrinkage. 525 Combined methods. 250 Cut and fill. 181 Room and pillar. 625 Do. 625 Combined methods. 1,656 Open pit. 192 Room and pillar. 1,797 Block caving. 324 Combined methods. 725 Room and pillar. 182 Cut and fill. 643 Open stope. 960 Room and pillar 113 Do. 490 Do. 544 Do. 272 Do. 400 Combined methods. 311 Sublevel caving. 709 Do. 228 Room and pillar. 625 Combined methods. 625 Do. 625 Do. 625 Room and pillar. 625 Combined methods. 625 Room and pillar. 2,041 Do 625 Combined methods. 275 Do 272 Room and pillar. 525 Do. 68 Do. 136 Shrinkage. 568 Combined methods. 400 Do. 625 Room and pillar. 625 Do. 400 Do 794 Do. 544 Do. 544 Do. 635 Sublevel open stope. 2,820 Do. 114 Room and pillar. 355 Cut and fill. 340 Room and pillar. 500 Do. 600 Overhand square set. 1,000 Open stope. 1,100 Do. 710 Combined methods. 710 Open stope. UNITED STATES Alaska: Arctic Camp Greens Creek Lik Red Dog Colorado: Black Cloud Idarado Sunnyside Idaho: Bunker Hill Star Morning Illinois: Minerva No. 1-Spivey . . . Kentucky: Surkesville Project Fountain Run Maine: Bald Mountain Kerr American-Blue Hill Montana: Butte District Zinc Nevada: Ruby Hill Mine Ward Mountain New Jersey: Sterling New Mexico: Pinos Altos New York: Balmat Pierrepoint Pennsylvania: Friedensville Mine Tennessee: Beaver Creek Big War Creek Carthage Property Copperhill: Boyd North-South Eureka-Calloway Coy Cub Creek Cumberland Cumberland Deposit Cumberland Property East Gainsboro Gainesboro Gordonsville-Elmwood Hartsville Hartsville Area Idol Immel Jefferson City Mine Lost Creek New Market Pall Mall Right Fork Roaring River Stonewall Young Zinc Washington: Boundary Dam-Metaline Falls . Washington Zinc Unit Wisconsin: Crandon Crawhall-Elmo No. 3 Pelican River Shullsburg-Bearhole FOREIGN Algeria: El Abed Argentina: El Aguilar Australia: Dugald River Elura Hilton Lady Loretta . Kennecott Copper Corp . Noranda-Others . Houston Oil & Minerals-GCO. . Cominco . ASARCO-Resurrection . Newmont Mining . Standard Metals Bunker Hill-Gulf Resources Bunker Hill-Hecla Mining . . Inverness Mining . Cominco-ASARCO-Others . . St. Joe Minerals Corp . Superior Oil Co . Kerr American-Black Hawk . Anaconda Copper Corp, . . . . Ruby Hill-Hecla-Others . Gulf Oil-Silver King Mianes . . New Jersey Zinc Co . Boliden-Exxon Minerals . . . St. Joe Zinc ..do New Jersey Zinc Co. do. do. . St. Joe Minerals-Others . Cities Services Corp . ..do . ASARCO . New Jersey Zinc-Others . Jersey Miniere Zinc Co . Exxon Minerals . St Joe Minerals-Others Getty Oil-Tennessee Zinc Dev. . . New Jersey Zinc-Others . Jersey Miniere Zinc Co . Marathon Oil-J. F. Landers . Cominco American-NL Ind . New Jersey Zinc Co . ASARCO . New Jersey Zinc Co . ..do . ASARCO . ASARCO-Others . ASARCO . New Jersey Zinc Co.-AMAX Inc. . Jersey Miniere Zinc Co . ASARCO . US Steel Corp . Metaline-Washington Res. . Callahan Mining-Others . . . Exxon Minerals Corp. . Inspiration Mines Noranda Corp . Inspiration Mines SONAREM St. Joe Minerals Corp. . CRA Ltd . EZ Industries Ltd . Mount Isa Mines (MIM) Ltd . Triako Mines NL-MIM Holdings. E E E E P PP P PP P P E E E PP PP E E P E P D P P E E P P PP E E E E E E P E E P PP P P P E E E E PP P PP PP E PP E PP P P E D D E See footnotes at end of table. Table 15.— Mines and deposits evaluated as zinc operations— Continued 13 Ownership Status' Type ; Est ore capacity, 10'tyr Mining methods 7.000 Combined methods. 3.600 Do 1.100 Do 200 Open stope. 675 Combined methods 300 Open pit. 1,050 Do. 900 Cut and fill. 500 Combined methods. 245 Cut and fill. 161 Shrinkage. 825 Room and pillar. 420 Bench (berm). 310 Do. 350 Cut and fill. 3,400 Open pit. 3,500 Cut and fill. 300 Do. 2,800 Do. 181 Sublevel open stope 1,750' Cut and fill. 529 Room and pillar. 450 Combined methods 222 Open pit. 350 Do. 286 Room and pillar. 496 Combined methods. 544 Open pit. 350 Room and pillar. 1,500 Cut and fill. 1,000 Do. 1,570 Open stope. 3,500 Combined methods. 733 Open pit 350 Cut and fill. 350 Do 508 Sublevel open stope. 1,476 Cut and fill. 495 Do. 562 Room and pillar. 3.290 Open pit. 749 Cut and fill. 315 Do 350 Open pit. 450 Room and pillar. 2,130 Sublevel caving. 700 Cut and fill 1,100 Sublevel open stope. 1,000 Do 260 Open pit. 260 Cut and fill. 182 Sublevel open stope 240 Cut and fill. 407 Do. 850 Sublevel open stope 277 Cut and fill 550 Sublevel caving. 800 Do. 640 Room and pillar 700 Combined methods 350 Open pit. 1.040 Top slicing 900 Open stope. 900 Shrinkage FOREIGN— Continued Australia — Continued McArthur River Mount Isa New Broken Mill Que River Roseberry-Hercuies Teutonic Bc-e Woodlawn Zinc Corporation Austna Bleiberg-Kreuth Bolivia Mati'de Quechisia Paracatu Vaza^te • 3awdwm Canada: Abcoun-Barvue Anvil Range Brunswick No 12 Buttle Lake Canbou Mine Cirque Daniels Harbor Detour Project F Group Gaiien Gays River Goidstream Goz Creek Great Slave Reef Hacked River Hatf Mile Lake Hearh Steele i Little River Joint Venture) Howard s Pass Izok Lake King Fissure Lyon Lake Martab: Mattaqami Lake B --'< =>0>nt Polans Praine Creek Resfjgouche Rotob Lake Sullivan Tom Finland: Pyhasalmi France Boden->ec Maiines Prxte-Aux-Moines Sa>m Saivy Germany Fed Reo of Grund Meggen Rammelsburg Greece: Mavres Petres-Madem Lakos Otymp»as Greenland Black Angel Honduras El Mochrto India Ambaji Mochja-Baiana Rajpura-Da'ba Zawarmaia-Barc* MIM Holdings Ltd MIM Ltd CRA Ltd Aberfoyle Ltd -Parmga Mining EZ Industries Ltd Seltrust-MIM Ltd St Joe-Phelps Dodge-CRA Ltd Zinc Corp Ltd Bleiberger Bergwerks Union COMIBOL do Mmeracao Morro Agudo Companhia Minena de Metais No 1 Mining Corp Abcourt Silver Mines-Noranda Cyprus Anvil Mining Corp Brunswick Mining and Milling Westmin Res. Ltd -Brascan Ltd. . . Anaconda Canada Ltd Hudson Bay Mining and Smelting. Cyprus Anvil-Hudson Bay Teck Corp Selco Mining Corp Ltd Noranda Mines Ltd Noranda-MacDonald Canada Wide Mines Ltd Noranda Mines Ltd Barrier Reef Resources Ltd Westmin-Dupont-Phihpp Bros Bathurst Norsemmes-Cominco Texasgulf Inc Heath Steele-Noranda-ASARCO Placer Dev -US Steel Corp Texasgulf Inc Internat Standard Resources Noranda Mines Ltd Noranda-Abitibi Mines Ltd Noranda Mines Ltd St Joseph-Sovereign Metals Mineral Resource Internat Pine Point Mines Ltd Cominco Ltd Cadillac Procan Explorations Placer Development Texasgulf-Arrow Inter Am-Bar Cominco Ltd Hudson Bay Mining and Smelting. Outokumpu Oy do BRGM Penarroya BRGM Penarroya Preussag AG Metail Sachtleben Bergbau Gmbh Preussag AG Metail Hellenic Chemical Prod Co do Cominco Ltd Rosario Resources-Amax Inc Gujarat Mineral Dev Hindustan Zinc. Ltd do do See footnotes at end of table 14 Table 15.— Mines and deposits evaluated as zinc operations — Continued Ownership Status 1 Type 2 Est ore capacity, 1 3 t/yr Mining methods 350 Sublevel. 700 Cut and fill. 600 Combined methods. 350 Room and pillar. 2,250 Combined methods. 350 Sublevel open stope. 950 Sublevel caving. 300 Combined methods 300 Cut and fill. 468 Combined methods 120 Top slicing. 240 Do. 444 Cut and fill. 329 Sublevel open stope 954 Do. 546 Cut and fill. 384 Do. 396 Do. 390 Combined methods. 300 Open pit. 140 Open stope. 124 Sublevel caving. 241 Combined methods 240 Sublevel open stope 756 Cut and fill. 218 Combined methods. 3.500 Open pit. 852 Shrinkage. 770 Cut and fill. 1,622 Combined methods. 312 Cut and fill. 1,026 Shrinkage. 1,034 Combined methods. 281 Shrinkage. 60 Overhand. 420 Sublevel open stope 460 Combined methods. 320 Do. 892 Do 2,113 Do. 432 Room and pillar. 273 Cut and fill. 600 Combined methods. 540 Cut and fill. 513 Combined methods. 350 Do. 636 Do. 406 Cut and fill. 300 Sublevel open stope 497 Combined methods. 429 Cut and fill. 3,000 Sublevel open stope 4,000 Open pit. 1,907 Do. 400 Room and pillar. 885 Cut and fill. 600 Room and pillar. 475 Cut and fill. 599 Do. 90 Open pit. 1,450 Combined methods. 240 Sublevel open stope FOREIGN— Continued Ireland: Ballinalack Noranda-Barymin , Bula Bula Ltd. -Govt, of Ireland Mogul Kerr Addison-Silvermines Sabina-Tatestown Sabine-Messina-lrish Base Met. Tara (Navan) Tara Exp. -Govt, of Ireland Italy: Funtana Raminosa SAMIM Masua do Monteponi do Montevecchio do Raibl do Japan: Ezuri Dowa Mining Co. Ltd Fukazawa do Hosokura Mitsubishi Metal Corp Kamioka: Mozumi Mitsui Mining & Smelting Tochibora do Kosaka Dowa Mining Co. Ltd Nakatatsu Nippon Zinc Mining Co. Ltd. . . . Toyoha do Mexico: Charcas Industrial Minera Mexico Cuale Cia. Fresnillo S.A El Monte;EI Carrizal do El Tecolote Industrial Minera Mexico Fresnillo Cia. Fresnillo S.A La Negra Industrias Penoles S.A Naica Cia. Fresnillo S.A Parral Industrial Minera Mexico Real De Angeles Minera Real de Angeles San Francisco Del Oro Frisco S.A. de C.V San Martin Industrial Minera Mexico Santa Barbara do Santa Eulalia do Santa Maria de la Paz Min. Santa Maria de la Paz . . Taxco Industrial Minera Mexico Velardena do Morocco: Bou Madine Government of Morocco Namibia: Rosh Pinah Imcor Zinc (Pty.) Ltd Peru: Atacocha Cia. Minera Atacocha S.A. . . . Carahuacra Volcan Mines Co. . .' Casapalca CENTROMIN Cerro de Pasco do Hercules Cia. Minera Alianza S.A Huanzala Cia. Minera Santa Luisa S.A. Huaron Cia. Minera Huaron S.A Milpo Cia. Minera Milpo S.A Morococha CENTROMIN Raura Cia. Minera Raura S.A San Cristobal CENTROMIN San Vicente San Ignacio de Morococha . . Santander St. Joe Minerals Yauncocha CENTROMIN Portugal: Aljustrel Empresa Minera D'Aljustrel . . South Africa, Rep. of: Gamsberg Gamsberg Zinc Corp Spain: Aznalcollar Soc. Andalusa de Piritas S.A.. Cartagena Penarroya Reocin Asturiana De Zinc S.A Rubiales Exminesa Sotiel Minas de Almagresa S.A Sweden: Garpenberg Boliden Zinkgruven Soc. des Mines et Fonderies . Turkey: Aladag Cinko-Kursan Metal Sanayii . . Zaire: Kipushi Gecamines Zambia: Broken Hill Nchanga Consolidated E E P E P P P D E P P P P P P P P P P P P P P P P P D P P P P P P P E P P P P P P P P P P P P P P P P E P P P P D P P P P P U U u u u u u u u u u u u u u u u u u s u u u u u u s u u u u u u u u u u c u c u u u u u u c u u u u u s s u u u u u s u u 1 D — developing deposit, E — explored deposit, P — producing mine, PP — past producer, T — temporarily shut down. 2 C — surface and underground, S — surface, U — underground 15 Table 16.— Mines and deposits evaluated as copper operations with lead and zinc as major byproducts (Property information as of January 1981) Ownership Status' Type : Est ore capacity. 10 J tyr Mining methods Australia Benambra CSA Canada Flin Flon Fox Geco High Lake Kidd C-eek Lake Dufauit Division Ruttan Finland Keretti Vuonos Japan Hanaoka Norway Tverreiellet Peru Antamma a Kombat-Asis West South Afnca Rep of Prieska Sweden Steke">|Okk Turkey Cayeii S rt Western Mining-British Petrol. Conzmc Riotinto of Australia Hudson Bay Mining and Smelting Sherntt Gordon Mines Ltd Noranda Mines Ltd Kennarctic Explorations Texasgulf. Inc Faiconbndge Copper Ltd Sherntt Gordon Mines Ltd Outokumpo Oy do Dowa Mining Co Ltd Folldal Verk AS Minero Peru Tsumeb Corp. Ltd Pneska Copper Mines Ltd. Boliden Metall AB Etibank do 520 Open pit. 875 Open stope. 702 Shrinkage. 702 Cut and fill. 1.588 Do. 312 Shrinkage. 4.393 Open stope. 420 Do 3.175 Do 500 Cut and fill. 550 Room and pillar. 876 Do. 650 Sublevel open stope 10,500 Open pit. 350 Combined methods. 520 Open stope. 600 Combined methods. 600 Cut and fill. 705 Shrinkage. ' D — developing deposit. E — explored deposit. P — producing mine, PP — past producer, T — temporarily shut down 1 C — surface and underground, S — surface. U — underground. GEOLOGY OF LEAD AND ZINC DEPOSITS The mineralogy of lead and zinc ores is relatively simple, with the sulfides galena (PbS) and sphalerite (ZnS) occurring as the major lead and zinc minerals, respectively. Most lead deposits contain galena asso- ciated with sphalerite, pyrite (FeS ._.), chalcopyrite (CuFeS i. and other base metal sulfides or sulfosalts, some of which are recovered to yield byproducts or co- products. Galena is usually associated with variable amounts of contained silver (argentiferous galena) ; galena low in silver is referred to as soft lead (8). Some galena ore bodies may be altered to cerussite (PbCO I, anglesite CPbSO,), or other oxidized lead minerals, but generally galena is resistant to weather- ing. Lead is a major constituent in several important deposit types, including stratabound, volcanic-sedi- mentary, replacement, veins, and contact metamorphic deposits. The major zinc deposits contain the zinc sulfide mineral, sphalerite. Most sphalerite has associated cadmium in quantities from traces to 2 pet, and small quantities of germanium, gallium, indium, and thal- lium. A few important zinc deposits contain oxide, carbonate, or silicate zinc minerals such as zincite CZnO). smithsonite CZnTO >, willemite fZm.SiO,), or hemimorphite 'Zn Si O. | OH i_«H.,0) ; commonly de- rived from the altered sulfide minerals. The two prin- cipal types of sulfide deposits are massive mixed sulfide ores in metamorphic rocks and irregular breccia or replacement stratabound deposits in carbonate rocka. A lesser number of sulfide deposits are classified as contact metamorphic. replacement, or vein deposits. The most ciimmon host rocks of stratabound lead and zinc deposits are limestones or dolomites. Sedi- mentary-structural features, such as reefs, facies changes, zones of minor jointing, or collapse breccias associated with ancient karst drainage, serve as loci for ore bodies within the favorable formations. Examples of such stratabound deposits are in the Southeast Missouri lead district; the Missouri-Okla- homa-Kansas district; the Upper Mississippi Valley district; the Pine Point deposit, Northwest Territory, Canada; the Laisvall deposit, Sweden; and the eastern Tennessee zinc deposits. Volcanic-sedimentary type deposits contain mas- sive sulfide bodies commonly interlayered with vol- canic or sedimentary rocks. Most such deposits are found in older folded and disturbed belts that have been severely metamorphosed. Their size can range from small lenses to enormous masses. The ore is commonly a fine-grained mixture of pyrite or pyrrho- tite, sphalerite, galena, and chalcopyrite, with minor amounts of nonmetallic and carbonate minerals. Examples of massive sulfide deposits are those near Bathurst, New Brunswick, Kidd Creek, and Sullivan in Canada; Broken Hill and Mount Isa, Australia; and Kuroko, Japan. Replacement deposits of lead and zinc are com- monly irregular hydrothermal type deposits in car- bonate rocks, but some also occur in quartzites or metamorphic rocks. The form and extent of the ore bodies are determined by the structural and strati- graphic elements that localized the replacement ac- tivity of the ore-bearing solutions. They include tabu- lar or cylindrical flat-lying bodies called mantos, pipelike structures that cross the bedding, and irregu- lar branching bedded deposits associated with veins. Some of the well-known replacement deposits include Cerro de Pasco, Peru; the silver-lead district of Cen- 16 tral Mexico; Tsumeb, Namibia; Tintic, Utah; and Leadville and Gilman districts, Colorado. Veins are the best known type of ore deposits. They are the most obvious and consequently were the first deposits to be exploited by ancient miners. The vein deposits are commonly situated in faults, joints, or at formational contacts. They contain ore minerals and gangue in varying amounts. Veins can be 1 to 10 m long horizontally, and extend downwards hundreds of meters. Some of the better known vein systems occur in the Coeur d'Alene district in Idaho; the Silverton area of Colorado; Santa Barbara, Fresnillo, and Taxco Mines in Mexico; and the Harz Mountains, Clausthal, and Freiberg deposits in Germany. Contact metamorphic deposits are associated with igneous intrusions, which have either provided the solutions or emanations creating the deposit, or have altered and recrystallized (or replaced) a mineral deposit already present prior to the intrusion. De- posits range in size from small vein systems to massive pods hundreds of meters long. Although many deposits of this type are mined for other metals in the United States, only a few have produced significant amounts of lead, usually as a byproduct. The Kamioka, Obori, Chichibu, and Nakatatsu deposits in Japan are ex- amples of this type of deposit. A description of geological characteristics related to major important lead-zinc occurrences throughout the world is presented in the appendix for countries of six continents. Countries having a small percentage of the total world lead-zinc resource are not discussed. MINING METHODS AND OPERATING COSTS Lead and zinc ores are primarily exploited by underground mining methods. Of the 235 market economy deposits investigated, 211 were analyzed as underground operations, 134 of which were producing mines. Producing mines account for approximately 46 pet of the zinc and 66 pet of the lead and silver poten- tially available from all deposits evaluated. The deposits were divided into six general mining method categories for analysis. These categories are surface, open stope, filled stope, caving, shrinkage stope, and combinations of underground categories. Figure 5 and table 17 show annual ore capacity in- formation by specific mining method for producing mines and undeveloped deposits. The 145 producing mines have a total ore capacity of 113 million t/yr with an average capacity of 780,000 t/yr. About 45 pet of this annual capacity is from small mines producing less than 1 million t of ore per year, and approximately 85 pet of the small mine capacity is from underground operations. Open stope is the most common mining method, accounting for nearly 31 pet of the annual production capacity of producing mines. Undeveloped deposits have a potential production capacity of 84 million t of ore per year, 73 pet of which would likely be produced by underground meth- ods. As shown, production using underground methods would be spread nearly equally between combined, filled stope, and open stope methods with the re- mainder using caving and shrinkage methods. About 42 pet of the potential capacity would be from small mines having capacities of less than 1 million t of ore per year. The selection of a mining method for the ex- ploitation of a mineralized body depends on a number of factors. A few of the most important are depth, geometry, structure, and attitude of the deposit. Addi- tional factors are strength of the mineralized body and surrounding wall rock. Climate and location may influence the decision to go with an underground rather than surface method because of severe weather PRODUCING MINES (Annual ore capacity 113 X I0 6 t) UNDEVELOPED DEPOSITS (Annual ore capacity 84 X I0 6 t) Figure 5. — Share of annual ore capacity, by mining method, for producing and undeveloped lead and zinc mines and deposits. 17 Table 17.— Mining methods and costs for producing and undeveloped lead and zinc mines and deposits Producing Undeveloped Mines- deposits Annual ore capacity. ^Q' t Average Total Cost per metric ton ot ore Mines- deposits Annual ore capacity, 10 3 1 Average Total Cost per metric ton of ore Surface Open stope Riled slope Caving Shrinkage Combined underground Total or average 11 39 34 23 4 34 1.500 900 590 610 360 770 16.500 35.000 20.070 14.090 1,420 26.260 $7.40 12.70 21 70 17.40 26 60 23 70 13 33 17 7 3 17 1.760 500 930 1,310 640 1.060 22.860 16.390 15.880 9.160 1.920 18.040 145 780 113.360 1840 90 940 84,250 $9.30 15 20 24.70 18.10 20.20 13.90 17.90 ' Average stnppmg ratios — producirg mines. 4 4:1; undeveloped deposits. 3.3:1 Average operating cost per metric ton of matenal moved — producing mines. $1 40: undeveloped deposits, $2 20 conditions or proximity to populated areas or bodies of water (Jakes, rivers, oceans, etc.). SURFACE MINING Surface mining requires a relatively shallow deposit with the stripping ratio (tons of waste rock to tons of orei normally under 5:1. A typical surface lead-zinc mine uses rotary blasthole drilling machines to drill the blasting rounds, which are charged with ANFO. The blasted ore is loaded with either diesel- electric shovels or front-end loaders into trucks for haulage to the mill. (At Pine Point in the Northwest Territories, Canada, a dragline is used to remove and dispose of blasted overburden prior to mining ore.) For surface operations, average mine recovery is 90 pet with a 4-pct dilution factor. Eleven producing surface mines were evaluated for this study, five of which were small operations averaging 340.000 t/yr ore capacity while the six larger operations averaged nearly 2.5 million t/yr. Thirteen undeveloped deposits were evaluated as po- tential surface operations. Nine of these deposits averaged 510.000 t/yr ore capacity while the remaining four deposits averaged nearly 4.6 million t/yr. Surface mine operating costs are dependent on a wide range of variables, such as location and physical characteristics of the deposit and degree of mechani- zation. High mining costs per ton of ore for some mines are due to their remote location where costs of labor, supplies, and power are high. Large-capacity mines tend to be highly mechanized, efficient opera- tions. Smaller capacity mines, on the other hand, tend to be more labor intensive and require higher ore grades to operate profitably. An important cost factor irface mines is the stripping ratio, which meas- ures the tons of waste which must be mined to recover each ton of ore. The 11 producing mines have an average mining cost per metric ton of ore f?1.40 per metric ton of material) with an average stripping ratio of 4.4:1 (table :"or the undeveloped deposits average S9.30 per metric ton of ore ($2.20 per metric ton of material) with an average stripping ratio of 3.3:1. Estimated undeveloped mining per metric ton of ore average 25 pet greater than producing mines. UNDERGROUND MINING Underground mining method selection depends primarily on the attitude, depth, and dimensions of the mineralized body as well as the strength of the wall rock and mineralized body. The mining cycle for underground mining is similar from one mining method to another with type of equipment and degree of mechanization being the major variables. Drilling is performed by jackleg drills in smaller mines while jumbo drills are used in the larger, more mechanized mines. Dynamite, in the form of cartridges, is norm- ally used as the blasting agent, and it is initiated by electric blasting caps. Loading of broken ore and waste is performed by diesel or electric load-haul- dump (LHD) machines in the more mechanized mines while the smaller mines use overshot mucking ma- chines and manual shovel loading of ore carts. Trans- portation of ore and waste within the mine is pri- marily by truck or train with ore passes used to transfer material to the main haulage levels. In some cases, when the haul distance is relatively short, LHD machines perform both the loading and transportation functions. Access to underground mines is either by adit, incline, vertical shaft, or a combination of the three. Mode of access depends on the local topography and depth to the working areas. Shallow deposits or deposits in mountainous terrain may be accessed by adits or inclines while deeper deposits invariably are accessed by shafts. Open stope mining is characterized by strong and competent ore and country rock requiring a minimum of artificial support during the mining cycle. A hori- zontal to shallow dipping tabular ore body is developed by a series of interconnected rooms excavated in a regular or irregular pattern with pillars left for sup- port. This mining method is well suited for a high degree of mechanization because of large openings that make the access of large capacity equipment possible. Room-and-pillar and breast stoping are the princi- pal types r 'f open stope mini)n r u i 'I in lead and zinc mining. All of the Missouri lead-zinc mines and a majority of the Tennessee zinc mines use the room- and-pillar mining method. Open stope mining accounts cing and 19 pet of potential un- developed annual ore capacity in market economy countries. 18 Filled stope methods are used when the country rock or the mineralized body or both are too weak to allow excavated openings to remain open during the mining cycle. Some form of cut-and-fill operation is employed to provide the necessary support for the stope walls and back. Following the drilling, blasting, and loading operations in the mining cycle, the stope is backfilled with either waste rock or the sand portion of classified mill tailings. Both horizontal and inclined cut-and-fill stope methods and one square-set operation are included in the filled stope category. Approximate- ly 18 pet of producing and 19 pet of potential un- developed annual ore capacity from underground mines in market economy countries is from filled stope methods. Caving methods require the mineralized body to be weak enough to cave because of gravity once sup- port is removed. Drilling and blasting is restricted to development work. The loading and hauling operations are essentially the same as other underground methods with similar degrees of mechanization. Caving meth- ods provide 12 pet of the producing and 11 pet of the potential undeveloped annual ore capacity. Shrinkage stoping is similar to cut-and-fill stoping except that the broken rock filling the stope during the mining cycle is ore instead of waste or mill tail- ings. The ore is drilled and blasted in horizontal slices on a steeply dipping tabular ore body. The broken ore becomes the working floor for subsequent drilling. Sufficient ore is removed from the bottom of the stope to maintain an adequate working space from which to drill the next slice. One of the drawbacks to using this method for lead and zinc ores is that the high pyrite and other sulfide content of many deposits tends to oxidize in the stope causing poor flotation recovery in the mill. Only 1 pet of the producing and 2 pet of the proposed undeveloped annual ore capacity is from shrinkage method operations. Some mines use a combination of mining methods because of the difference in physical conditions from one part of the deposit to another. Mining methods may change through time because of economic con- siderations to maintain or improve the competitiveness of an operation. Approximately 23 pet of the produc- ing and 21 pet of the proposed undeveloped annual ore capacity is from mines that use or may use a com- bination of mining methods. Operating costs were also estimated for the 211 underground lead and zinc mines and deposits, 134 of which were producing as of January 1981. Indi- vidual deposit characteristics, such as location, stope width, depth, rock support requirements, and degree of mechanization all contribute to creating a wide range of operating costs. Among producing mines, open stope is the most common underground method with an average capacity of 900,000 t/yr and the lowest underground mine operating cost at $12.70 per metric ton. The shrinkage method, with an average mine operating cost of $26.60 per metric ton of ore, is the highest cost method and has the lowest average capacity, 360,000 t/yr. BENEFICIATION METHODS AND OPERATING COSTS With the exception of the high-grade Sterling Mine in New Jersey and the Aladag Mine in Turkey, which produce direct shipping ore, all of the properties evaluated for this investigation use conventional crushing, grinding, and differential flotation as the primary beneficiation method. Individual flowsheets will differ in detail because of characteristics of the ore and number of concentrates recovered but all will have the same basic steps. Figure 6 is a simplified basic flowsheet for a typical lead-zinc-copper flotation mill. The ore is crushed, ground, and classified prior to flotation. Sometimes a heavy media separation cir- cuit follows the crushing circuit to remove waste prior to grinding. After flotation, the concentrates are thickened, filtered, dried, and stored for shipment. As many as three concentrates (lead, zinc, and copper), are generally produced in the flotation circuit. Zinc in the form of sphalerite is depressed, while copper in the form of chalcopyrite, and lead in the form of galena, are floated. The copper and lead con- centrates are then separated by floating copper fol- lowed by cleaning the copper and lead- concentrates. Tails from the first stage of flotation become the feed to the zinc flotation circuit. The zinc concentrate is cleaned and all three concentrates are subsequently thickened, filtered, and dried. When the grind sizes are very small (minus 200 Run-of-mine ore i Crushing (staged) i ersize Tails Ov Grinding I Classification i i Tails Bulk copper-lead flotation Copper flotation Solid-liquid separation 1 Regrind Solid-liquid separation Lead concentrate to smelter Zinc flotation Copper concentrate to smelter Solid-liquid separation Final tailings to disposal Zinc concentrate to smelter Figure 6. — Basic flowsheet for a typical copper-lead-zinc flotation mill. 19 mesh"* because of fine sulfide grain sizes or intimate ore mineral associations, it is not practical to produce separate concentrates owing to poor liberation of the lead and zinc minerals. This situation would result in very poor recoveries and or very low quality concen- trates if separate concentrate production were at- tempted. In such cases, a bulk lead-zinc or lead-zinc- copper concentrate is produced. Further treatment would most likely be in an Imperial Smelting Corpora- tion blast furnace (Imperial smelting furnace), which is designed for handling bulk lead-zinc concentrates. Table 18 shows average estimated milling costs by ore capacity range. The number of concentrates pro- duced, grinding size, and power and labor rates are a few of the more important factors affecting these costs. Average mill operating costs range from $6 per metric ton of ore for operations with annual ore capa- cities greater than 2 million t to $8.60 per metric ton of ore for operations with annual ore capacities less than 500.000 t. Table 18. — Estimated average mill capacity and operating cost Mine ore capacity. Mines- Mill ore capacity Cost per metric 10 s tyr deposits 10 3 tyr ton of ore <0.5 107 290 $8 60 0.5 to 1.0 79 680 6.70 1.0 to 2.0 27 1.370 6.10 >2.0 21 3.580 6.00 Total or av 234 840 6.60 Most lead and zinc deposits in the United States are metallurgically simple and tend to be at the lower end of milling operating costs. With the exception of Ducktown, the Tennessee zinc deposits are essentially single mineral deposits and the Missouri lead-zinc deposits are primarily coarse-grained galena with low sphalerite content. The higher cost operations are primarily due to complex ores that require extensive grinding and separate flotation circuits to recover separate, clean, marketable concentrates of lead, zinc, and copper. SMELTING AND REFINING As of 1981. world lead smelter capacity was 4.765.000 t and lead refinery capacity was 4,699,000 t p. 7). The market economy countries had an esti- mated 3.257.000 t of lead smelting and 3,228,000 t of lead refining capacity in 1981. Lead smelting tech- nologies include the conventional blast furnace, Im- perial smelting furnace, and electric furnace processes. Lead refining technologies use both pyrometallurgical and electrolytic processes. World zinc refining capacity in 1981 was 7,477,000 of zinc, of which 5,839,000 t was from market economy countries. Zinc refining technologies utilize electrolytic, Imperial smelting furnace, electrothermic, and horizontal and vertical retort techniques for the recovery of zinc from concentrates. Table 19 shows a breakdown of capacities by smelting and refining methods by region. The relative importance of the various extractive metallurgical techniques used in the lead and zinc industry ha? changed significantly in the past two decades. Lead smelting by conventional blast furnace technology has increased from 80 to 89 pet from 1968 "31 while electric furnace processes have decreased in relative importance by the same amount (table 20). The Imperial smelter furnace has remained unchanged in overall importance, accounting for about 8 pet of capacity. The trend in lead refining is to pyrometal- lurgical versus electrolytic, with an increase of 8 pet from 1968 to 1981 for the pyrometallurgical process production capacity. An estimated 78 pet of lead refin- ing capacity utilizes pyrometallurgical methods. Zinc extraction technology has undergone a major shift towards electrolytic refining away from hori- •Zlnc refining, aa uaed In tola Investlgotlon, refers primarily to electrolytic zinc refining but doea include some zinc recovered through pyrometallurgical Hmeltlog technology. zontal and vertical retort technology (table 21). The technological reasons for this shift are reduced re- covery, low energy efficiencies, and high levels of pollution effluents and emissions from the horizontal and vertical retorting plants. Electrolytic methods Table 19. — Market economy country 1981 lead and zinc smelt- ing and refining capacity, by region, thousand metric tons metal , . u Europe Africa Asia Oceania Total America America r Lead smeltm y (furnace): Conventional blast 1.212 207 717 150 235 380 2.901 Impenal smelting 144 30 49 30 253 Electric 55 48 103 Total 1.212 207 916 180 332 410 3.257 Lead refining: Pyrometallurgical 934 141 944 180 80 230 2.509 Electrolytic 309 90 50 270 719 Total 1.243 231 994 180 350 230 3.228 Zinc refining: Electrolytic '1.280 294 1.804 213 848 260 4.699 Impenal smelting furnace .. 389 34 136 70 629 Electrothermic 77 25 18 125 245 Horizontal retort 100 25 125 Vertical retort 25 116 141 Total 1.457 319 2,261 247 1,225 330 5.839 ' Includes capacity of Luis Potosi. Mexico, zinc refinery that started production in 1 982. Sources: Bureau of Mines data and reference 9 Table 20.— Comparison of 1968 and 1981 lead smelting and refining methods, share of production, percent Process 1968 1981 Smelting (furnace) Conventional blast 80 89 Imperial smelting 8 8 Electric 12 3 Refining: Pyrometallurgical 70 78 Electrolytic 30 22 Sources Bureau of Mines data and reference 10 20 Table 21 .—Comparison of 1958, 1968, and 1981 zinc refining methods, share of production, percent Process 1958 1968 1981 Electrolytic 50 56 81 Imperial smelting furnace 8 11 11 Electrothermic 3 4 4 Horizontal retort 32 15 2 Vertical retort 7 14 2 Sources: Bureau of Mines data and reference 10. Table 22. — Typical smelter and refinery recoveries and product grades, percent Smelter Refinery Concentrate and commodity Recovery Grade Recovery Grade Zinc: Zinc NAp NAp 95 99.9 Cadmium NAp NAp 90 99.95 Gold NAp NAp 97 99.99 Silver NAp NAp 97 99.99 Lead NAp NAp 97 99.9 Lead: Lead 97 98.5 99 99.9 Gold 99 NAp 99.9 99.99 Silver 99 NAp 99.9 99.99 Copper: Copper 97 98.5 99 99.9 Gold 99 NAp 99.9 99.99 Silver 99 NAp 99.9 99.99 Bulk lead-zinc: 1 Lead 95 98.5 99 99.9 Zinc 78-91 98.5 99 99.9 Silver 99 NAp 99.9 99.99 Gold 99 NAp 99.9 99.99 NAp Not applicable. 1 Imperial smelting furnace. presently account for about 81 pet of market economy and 84 pet of U.S. zinc refining capacity. Typical smelter and refinery recoveries and prod- uct grades that can be expected for zinc, lead, copper, and bulk lead-zinc concentrates are listed in table 22. These are averages of values used in the evaluation of individual operations. Zinc recovery from zinc concen- trates ranged from 90 to 97 pet and lead recovery from lead concentrates ranged from 92 to 98 pet. The range in lead recoveries from a bulk lead-zinc or lead-zinc- copper concentrate processed by the Imperial smelting furnace did not differ significantly from that experi- enced with a simple lead concentrate, but zinc recovery from a bulk lead-zinc concentrate ranged considerably lower at 75 to 85 pet. This recovery could be increased by fuming the furnace slag for additional zinc, lead, and cadmium recovery. Copper recoveries generally range from 95 to 98 pet. LEAD SMELTING Conventional Blast Furnace The most widely used method for producing metallic lead is the blast furnace, which accounts for 89 pet of market economy country lead production capacity (table 20). Figure 7 shows a simplified schematic of a conventional blast furnace operation. Lead sulfide concentrate feed is first sent through a Ottgases to atmosphere "Black" sulfuric acid to market Dust and tume to storage Sulfur dioxide removal Dust and fume collection (wet and/or dry) Offgases to atmosphere Dust and fume to storage Dry dust and fume collection High sulfur-dioxide content offgases Concentrate Feed preparation and blending Feed conditioning and agglomeration Limestone Iron ore Silica Slag Undersize sinter Dust and tume Low-sulfur -dioxide content offgases Sinter crushing and sizing 1 Blast furnance reduction Lead bullion to refiner Undersize sinter to storage s , ag , feed S | 0rage and disposal (optional zinc fuming) Figure 7. — Simplified schematic of a typical lead smelter using conventional blast furnace technology. 21 sintering plant to form sinter, a hard porous material suitable for charging to the blast furnace, and to remove most of the sulfur primarily as SO. gas. Generally, dust and fume containing lead, zinc, and cadmium oxide are collected in a baghouse and re- turned to the sinter plant. The sulfur dioxide in the offgas may report to a contact-type sulfuric acid plant or may be dispersed to the atmosphere through a tall smelter stack. The sinter is charged with coke and fed to the blast furnace where it is reduced to lead and collected at the hearth off of the furnace. Molten slag is tapped above the lead and is normally granulated for return to the sintering plant or to slag dumps. Crude lead is either tapped from the bottom of the settler or re- covered via a leadwell to a drossing ladle for delivery to the drossing section of the refinery. The locations of currently operating conventional lead blast furnace smelters in the United States are Boss, MO (AMAX- Homestake). Glover. MO (ASARCO), Herculaneum, MO CSt Joe). East Helena, MT (ASARCO), and El Paso, TX (ASARCO). through a sintering plant to form lead- and zinc-bear- ing sinter and partially remove the sulfur and cadmium in the offgases. The cadmium is contained in a sludge collected in the gas scrubbing system and recovered in a separate refinery. Sulfur dioxide is primarily con- verted to sulfuric acid with some loss through the stack. The lead-zinc sinter is treated in an Imperial smelting blast furnace where the lead and zinc are reduced to metal. Zinc is volatilized and collected in the condenser section while the lead is tapped from the bottom of the furnace as crude lead for further refining. Zinc recovery in the condenser is discussed in more detail in the "Zinc Refining" section of this report. There are currently eight Imperial smelting furn- aces operating in market economy countries. These are located in Australia, France, Federal Republic of Germany, Italy, Japan (2), United Kingdom, and Zambia. Brunswick Mining and Smelting Co. con- verted Canada's only Imperial smelting furnace, in New Brunswick, to a conventional lead blast furnace in 1972. Imperial Smelting Furnace Imperial smelting furnace technology was de- veloped in the 1950's to treat combined lead and zinc concentrates, bulk lead-zinc concentrates, and concen- trates of oxidized lead and zinc minerals. Products are standard zinc grade metal, silver-lead bullion, and cadmium-bearing sludge. Approximately 8 pet of the lead production capacity in market economy countries is treated by this method (table 20). The Imperial smelting furnace is basically a con- ventional lead blast furnace with a zinc recovery sec- tion added (fig. 81. The concentrate feed is first sent LEAD REFINING The purpose of lead refining is to produce refined lead (99.99 pet Pb) and to recover metal byproducts. Two methods of lead refining, pyrometallurgical and electrolytic, are in use in the lead industry. The pyro- metallurgical method accounts for approximately 78 pet of market economy country primary lead refining capacity (table 20). The electrolytic refining method, used in Canada, Italy, Japan, and Peru makes up the remaining 22 pet capacity. A brief description of these two processes follows. Lead a conce nd zinc ■Urates Gas to atmosphere 4 Sinter machine Oftgas dust removal system Sulfuric acid plant Preheated coke — • 1 Sulfuric acid to market Imperial smelting blast turnance llion - Offgas scrubbing system Z nc vapor 1 to relmery ► Slag to dump : Lead Lead splash condenser t Cooling launder, lead-zinc separation bath K EY Solid Liquid Gas Zmc » Zmc holding bath ♦ Zmc Slab r Figure 8. — Simplified schematic of an Imperial smelting furnace plant. 22 Pyrometallurgical Electrolytic Pyrometallurgical refining starts with the copper drossing of molten crude lead to remove copper as a result of cooling and treatment with elemental sulfur. The next step is the softening step, which removes any impurities of antimony, arsenic, and tin. Oxygen- enriched air is bubbled through the molten bullion to form a dross comprising lead oxide with the oxides of these elements. The dross is treated at the refinery in a barrel furnace with coke to recover the lead and to produce an antimony-rich slag. These first two steps are normally performed as part of the blast furnace operation at the smelter for convenience even though they are the first steps in the lead refining process. Next, the molten bullion is desilverized by adding zinc. Silver and gold form an alloy with the zinc, which floats to the top of the melt as a crust where it is skimmed off. The zinc crusts are retorted to recover the zinc by volatilization. The remaining material, which comprises lead, silver, and gold, is roasted in a cupeling furnace and the lead is oxidized to litharge. The litharge is returned to the blast furnace and the remaining gold-silver dore is sent elsewhere for part- ing. The zinc remaining in the bullion after desilveri- zation is normally removed by vacuum distillation for reuse in the desilverization process. The final refining step is accomplished by adding caustic soda to remove any remaining antimony and zinc; the dross thus formed is recycled to the sinter plant. The final lead product is 99.99+ pet lead and is cast into ingots or pigs for shipment to market. A simplified flowsheet for pyrometallurgical refining is shown in figure 9. Electrolytic lead refining starts with the decop- perized molten bullion from the blast furnace being cast into anodes. Refined lead, usually in the form of rejected bars or blocks, is cast into the cathode starter sheets (although other metals, such as aluminum can also be used for the cathode starter sheets). The anodes and cathodes are placed in the electrolytic cells, and the cells are filled with electrolyte, normally hydro- fluosilicic acid and lead fluosilicate. Electric current is applied and it passes from the anodes through the electrolyte to the cathodes. Lead is transferred from the anodes to the cathodes during this process. Finish- ed cathodes grading 99.99+ pet lead are melted and cast into shapes for market. Slimes with high values of antimony, bismuth, silver, gold, and some residual lead adhere to the scrap anodes. The slimes are re- moved from the anodes and sent elsewhere for further treatment, and the scrap anodes are returned to the smelter. ZINC REFINING Electrolytic Electrolytic refining accounts for over 80 pet (table 21) of the current zinc production capacity in market economy countries. Zinc sulfides, primarily in the form of sphalerite, are roasted (usually in fluidized bed roasters) to convert the sulfides to an acid-soluble sulfate and convert the sulfur to sulfur dioxide. This sulfur dioxide is removed with the roaster offgases c E Bullion Irom smelter I J Copper removal Soda ash Coke Copper rever- beratory furnance Anlimony removal —i 1 — * Slag = E ■ p J Re eye le 2inc I 1 t 1 I Silver Zinc Bismuth removal ^ removal removal <7) 5 i o c >« Zinc 0> retorts Bismuth > refinery Final cleanup casting Refined lead E a ^ oi en E "> Figure 9. — Simplified schematic of pyrometallurgical lead refining. 23 and treated in a contact-type acid plant to produce sulfuric acid. Calcine formed by roasting is treated in a sulfuric acid leach plant. Residues that settle out as a sludge in the leach plant are treated separately for the recovery of copper, cadmium, lead, silver, cobalt, and tin. The solution containing dissolved zinc is puri- fied through several stages to remove residual copper and cadmium prior to electrowinning. The purified leach solution is mixed with electrolyte and undergoes the electrolysis process in electrolytic cells in similar fashion as described in the "Lead Refining" section. The electrolytic zinc process differs from the lead process in that the transfer of zinc to the cathode is effected from the electrolytic solution rather than the anode. The anodes in an electrolytic zinc plant are fabricated from sheets containing 99 pet lead and 1 pet silver. The cathode starter sheets are normally fabricated from aluminum sheet. The cathodes (which grade 99.99-t- pet zinc) are stripped, melted, and cast into shapes for market. A simplified flowsheet of the refining process is shown in figure 10. Zinc suilide concentrate Gas lo atmosphere I ■— * O'igas Oust removal system » (caicme) t » seca^ation *c - eacr> (residue) • Solution P u Doooe. m iron oreoD'iation t i alio" Sond-Howd 11 2liO<"i Suilunc acid plant . I Sui'unc acid to market t -ODoer * sreciD'Taie Solution DiS'fiCat'On (cadmium removal) 5 ~, - - z - - _L_ 1 e r^' o*X'**catKK! i- ,--_ »-• -:- . >-ie- ' I" - removal) r - 9u0 ~~ Leacn residue (lead, silver) to ieao smelter , Cadmium orecioitate to cadmium pianl ■ 1 to Cisoosai Z-nc eiect'ow*- -■■ Scent electrolyte Sol.d or DulD Liouid Gas ...... . _ ,. . f . . Figure 10. — Simplified schematic of an electrolytic zinc refinery. Imperial Smelting Furnace The Imperial smelting furnace process provides 11 pet of market economy country zinc capacity (table 21 "i. The lead recovery portion of this extraction was discussed previously. In this process, the zinc vapor is removed from the top of the lead blast furnace and passed through a condenser where the zinc is mixed into a molten lead spray. The molten lead-zinc mixture is cooled until the zinc separates from the lead and rises to the top of the holding tank. Zinc is recovered as prime western grade (98.0 to 98.5 pet zinc) which can be further refined by distillation to special high- grade specifications equal to electrolytic zinc (99.99 pet zinc). The molten lead is recycled to the condenser. This method of zinc extraction provides a lower zinc recovery (approximately 96 pet) than the electrolytic process but provides the advantage of being able to treat lead-zinc ores that do not respond well to differ- ential flotation and the ability to recover the lead and silver values in zinc concentrates in a single process, whereas the electrolytic process must rely on retreat- ment of lead and silver residues in a blast furnace. Electrothermic The electrothermic process for zinc extraction was first developed by St. Joe Minerals Corp. and put into commercial operation during 1930 at Monaca. PA. The relative importance of this method has re- mained the same over the last two decades at 4 pet of world market economy country zinc extraction capacity (table 21). The zinc sulfide concentrate is first roasted then sintered in preparation for the charging of the resistance-type electric furnaces; lead and cadmium are removed during roasting and sinter- ing. The flow of current through the sintered ore and coke charge develops the energy required for smelting at the reaction sites. To produce zinc oxide, the furn- ace vapors are oxidized with air. or to produce zinc metal the furnace vapors are bubbled through a zinc bath where the zinc is condensed. A simplified flow- sheet for the electrothermic process is presented in figure 11. Horizontal Retort The horizontal retort process is one of the oldest methods used for zinc metal recovery with commercial adaptation as early as 1800. This process represented only 2 pet of market economy country zinc production capacity in 1981 as compared to 32 pet in 1958 (table 21). The decline in use is primarily the result of in- creased labor and energy costs, and the control of particulate emissions. Zinc sulfide concentrates are first calcined in mul- tiple hearth roasters. Roaster gases are cleaned in electrostatic precipitators and sent to an acid plant to produce sulfuric acid or arc discharged to the at- mosphere through the stack. The calcine is intered to produce a sinter product suitable for feed to the horizontal retorts. Cadmium is volatilized in both the roasting and sintering operations and is collected as residue (from roasting) and fume (from sintering) 24 Coke Zinc concentrate (Optional) Gas to atmosphere Roaster Otfgas dust removal system Sulfuric acid plant T e ■ Su furic acid Sinter machine Offgas dust removal system To cadmium leach plant i ■» Residue I * Electrothermic furnance Zinc oxide furnance Oxide recovery and packing plant Zinc vapor ! ' — i X Condenser Fractional distillation to market * * -*• Dross KEY Zinc casting Zinc casting 1 + Slab zinc to market 1 ♦ Special high-grade zinc to market Gas Figure 11. — Simplified schematic of an electrothermic zinc plant. for further processing and recovery. The retorts are manually filled with sinter mixed with pulverized coal and charged in a batch process to volatilize the zinc. The zinc in the charge is reduced and distilled in the gas-fired furnaces, and the distilled zinc is collected in condensers and cast into slabs of prime western zinc, which can be further refined in a distillation process to produce a special high-grade product (99.99 pet zinc) for market. Only two horizontal retort plants are still in operation in market economy countries, both of them in Mexico. leading from an upper extension of the retort and are drawn into a zinc vapor condenser from which the liquid zinc is withdrawn for casting as prime western zinc or further refined to 99.99+ pet purity. A simpli- fied flowsheet for the process is illustrated in figure 12. The United States has one vertical retort plant at Palmerton, PA, that is currently closed and not ex- pected to reopen. Two other plants are still operating in market economy countries, one at Anby, France, and the other at Miike, Japan. Vertical Retort Zinc concentrate Zinc concentrate Vertical retort plants have faced a decline in use similar to the horizontal retort plants and for similar reasons. Production capacity as a percentage of total market economy country capacity has dropped from 14 pet to 2 pet between 1968 and 1981 (table 21). Initial development of both the horizontal and vertical retort processes revolved around the availability of a cheap supply of natural gas. Modern vertical retorts were developed as a modi- fication of horizontal retorts with the vertical retort configuration having the advantages of continuous, mechanized operation giving higher production capa- city at a lower unit cost than the batch-type process of the horizontal retort. The feed preparation for the vertical retort is similar to that of the horizontal retort except that the smelting charge is supplied in the form of briquettes. The briquettes, made from a sinter, bituminous coal, anthracite fines, and clay mixture, are first processed in a coking furnace for strengthening. They can then withstand handling and introduction into the vertical retort without disinte- grating. The vertical retort operates on a continuous basis with the introduction of new briquettes into the charge column to replace the reduced briquettes that are continuously withdrawn from the bottom of the retort. The zinc vapor and reaction gases produced flow upward through the retort and escape via a duct Roaster Coal Briquette press Coker Vertical retort Zinc vapor Splash condenser Holding furnance Zinc casting Slab zinc to market Sinter machine Offgas dust removal system ~- Residue Sulfuric acid plant Fractional distillation Zinc casting Gas to atmosphere Sulfuric acid to market KEY Solid — Liquid Gas -» Dross Special high-grade zinc to market Figure 12. — Simplified schematic of a vertical retort zinc plant. 25 OPERATING COSTS Operating costs for mining, beneficiating. trans- portation, and smelting-refming were estimated for each mine or deposit. Where possible, actual operating costs were collected from published sources or contacts with company personnel. When actual costs were not available, costs were either estimated using standard- ized costing techniques or derived from the Bureau's cost estimating system (CES) (2). The average total cost calculated for each of the mines and deposits investigated covers mining, bene- ficiation, transportation, smelting-refining, capital re- covery, taxes, and profit. These costs often vary great- ly depending on such factors as size of the operation, mining method, deposit location, stripping ratio, depth of the ore body, mill feed grades, complexity of mill feed, processing losses, energy and labor rates, pro- ductivity, and country and local tax structures. The operating costs presented in this section are weighted averages on a per-metric-ton-of-ore basis for mine and mill operating costs and per-metric-ton-of- concentrate basis for transportation costs and smelting-refining treatment charges. MINE AND MILL Weighted-average surface and underground operating costs, by country, for producing and un- developed lead and zinc deposits are presented in this section. Costs for some countries have been aggregated to avoid disclosing individual deposit data. Costs are shown in dollars per metric ton of ore for mining and milling, and per pound of recoverable metal for each stage of production. Lead Mines and Deposits The operating costs for the 22 producing lead mines included in table 23 averaged $12.00 per metric ton of ore for mining and $5.40 for milling. Mine operating costs in the United States averaged about one-half the cost of mining in foreign countries, primarily because the Missouri room-and-pillar mines are highly mechanized, low-cost producers. Mill operat- ing costs for U.S. lead mines are lower than foreign costs (averaging $5.20 per metric ton of ore com- pared with $6.30). because of the simple nature of domestic ores which require less processing. For the same reasons mentioned for producing mines, the five undeveloped deposits in the United States have an average mine operating cost approximately one-half that of the three undeveloped foreign deposits. Mill operating costs would average almost the same for foreign and domestic undeveloped deposits. Average lead ore grades for producing domestic and foreign mines are nearly equal, but grades for undeveloped domestic deposits average 70 pet higher than those of foreign deposits. Zinc Mines and Deposits The operating costs for the 109 producing zinc mines included in table 24 averaged $17.10 for mining and $8.20 for milling. Mine operating costs in the United States averaged about 80 pet of the cost of mining in foreign countries (although Spain averaged only 40 pet of the U.S. mining cost because most of the capacity was from low-cost surface mines), pri- marily because of the Tennessee room-and-pillar mines, which are highly mechanized, low-cost pro- ducers. The average United States mill operating cost is 35 pet lower than that for foreign producers ($5.50 versus $8.50), because of the simple mineralogy of the Tennessee mine ores, which require less processing. The 77 undeveloped zinc deposits have an esti- mated average mine operating cost of $13.80 and a mill operating cost of $6.00 per metric ton of ore. U.S. undeveloped deposit mining operating costs are estimated to be 30 pet less than foreign costs (averag- ing $11.20 compared with $16.20 per metric ton ore), because of the high degree of mechanization and productivity inherent in the Tennessee room-and-pillar operations. Mill operating costs do not vary significant- ly between U.S. and foreign deposits. Table 23.— Estimated mine and mill operating costs for producing and undeveloped lead mines and deposits PlfOduc "5 es Foreign countries United Stales Total or average Undeveloped deposits Foreign countries United States Total or average Mines- Recoverable ore.' 10 3 t Average ore grade Production potential 3 Operating cost per deposits Zinc. Lead, Silver, pet pet 2 g t Zinc. Lead, Silver, 10 3 t 10 3 1 10 3 troz metric ton Mine Mill Total 13 9 116,288 295,690 1 75 1 06 5 86 572 640 '234 1.375 2,208 6,005 16,105 203,970 191,384 $18.30 9.80 $6 30 5.20 $24.60 1 5 00 22 411,978 1 26 576 348 3,583 22,110 395,354 12.00 5.40 1/ -10 3 5 92.301 41.418 73 87 2.85 487 292 5 6 1 438 247 2,168 1.928 64,834 7,282 18.20 970 6.40 6.30 24 60 16.00 6 133.719 77 348 22 1 6 684 4,096 72,116 15.50 6 30 2180 ' Includes mining recovery and dilution 2 To convert from grams per metric ton to — troy ounces per short ton. multiply by 0291667; troy ounces per metric ton, multiply by 0321507 1 Includes alt mm, smelter and refinery recoveries over the life of the property 4 Silver grades for Missouri mines average 1 1 g i 5 3 of the 4 M«soun lead-zinc properties have no reported recoverable silver • Data do not add to total shown because of independent rounding 26 Mines- deposits Recoverable ore, 1 I0 3 t Average ore grade Zinc, Lead, Silver, pet pet 2 g/t Production potential 3 Zinc, Lead, Silver, 10 3 t 10 3 t 10 3 troz Operating cost per metric ton Mine Mill Total Table 24. — Estimated mine and mill operating costs for producing and undeveloped zinc mines and deposits Producing mines' Australia 7 111.200 8.56 6.23 116.6 7,417 5,879 360.192 $23.20 $6.10 $29.30 Canada 13 350,500 6.29 2.90 54.7 17,129 7,746 476,626 15.80 9.90 25.70 Germany. Fed. Rep. Of .. . 3 25,000 8.45 2.27 29.0 1,862 405 17,750 25 40 12.10 37.50 Italy 4 30,200 4.16 1.31 13.7 927 312 11,203 15.00 5.60 20.60 Japan 8 62,600 4.21 .74 38.3 2,313 361 55,945 21 .20 7.80 29.00 Mexico 15 140.200 4.63 1.82 139.1 4,947 2,132 508,117 20.90 7.00 27.90 Peru 14 100,400 6.78 2.77 108.1 5,347 1,971 252,150 23.20 10.80 34.00 Spain 4 119,400 2.46 .99 27.9 2,204 787 20,250 5.60 9.00 14.60 Other 25 335,600 5.88 1.28 30.0 15,558 4,072 336,015 17.20 7.80 25.00 Total or average . United States Total or average Undeveloped deposits: Australia 293,700 9.31 4.53 65.7 15,772 7,585 373,928 13.90 4.60 18.50 Canada 20 261,800 6.32 1.99 44.0 13,118 4,108 268,520 21.40 7.60 29.00 India 3 71,500 4.51 2.07 16.7 2,171 1,001 28,282 24.50 7.10 31.60 Ireland 3 25,000 5.63 1.16 1,179 226 23.60 9.30 32.90 Other 8 305,200 4JH3 .86 35.7 10,876 1,587 240,222 11.50 6.50 18.00 Total or average 39 957,200 6.37 2.39 44.8 "43.117 14,507 910,952 16.20 6.30 22.50 United States 38 880,200 4^63 .69 16.9 o6,139 5,441 328,658 11.20 5.70 16.90 Total or awage 77 1,837,400 5.53 1.58 31.1 "79,255 19,947 1,239,610 13.80 6.00 19.80 1 Includes mining recovery and dilution. 2 To convert from grams per metric ton to — troy ounces per short ton. multiply by 0.0291667; troy ounces per metric ton, multiply by 0.0321507 3 Includes all mill, smelter, and refinery recoveries over the life of the property. 4 Data do not add to total shown because of independent rounding. 93 16 1,275,100 144,300 5.77 3.28 2.35 .14 64.8 2.7 "57,703 4,140 23,665 169 2,038,255 10,210 17.40 14.40 8.50 5.50 25.90 19.90 109 1,419,300 5.52 2.12 58.5 "61,842 23,834 2,048,465 17.10 8.20 25.30 SMELTING AND REFINING For the purpose of this investigation, all mineral concentrates were treated as if they were shipped to custom smelters-refineries. The cost of smelting and refining includes the treatment charge for processing the concentrates and various deductions and pay-fors on the metal content of the concentrates. Typical treat- ment charges, deductions, and pay-fors are listed in table 25 for various concentrates processed by the operations evaluated in this investigation. To determine typical revenues resulting from a concentrate, the grade deduction is first subtracted from the concentrate grade and the result is multiplied by the pay-f or percent in decimal form. The resulting quantity is what the smelter will pay for at the current market price minus the price deduction. The price deduction covers any further cost to refine the com- modity to a finished product. In the case of lead and copper, the price deduction (normally $0.07 to $0.10 per pound), is incorporated as part of the treatment charge. Treatment charges and smelter schedules vary significantly from region to region and sometimes from country to country. For example, $150 per metric ton was used as the charge for treating lead and zinc concentrates in Japan while in Europe, charges as high as $200 to $220 per metric ton were used for treating lead concentrate and $180 to $200 for zinc concentrate. Table 25. — Typical smelter schedules Commodity Grade deduction Percent paid for Price deduction Commodity G^e Percent Price deduction paid for deduction ZINC, AV TREATMENT CHARGE- -$184/t CONCENTRATE COPPER, AV TREATMENT CHARGE— $130/t CONCENTRATE 2 Zinc Cadmium . None . .0.2 units ' . 0.02 oz 85 60 75 70 50 None $1 ,00/lb $5.00/oz. $0.20/oz. None Copper 1 unit 100 None Gold 0.02 oz 95 $5.00/oz. Gold Silver 1 oz 95 $0.20/oz. Silver Lead . . 3 oz 3 units BULK LEAD-ZINC, 3 AV TREATMENT CHARGE, $210/t CONCENTRATE LEAD, AV TREATMENT CHARGE- -$176/t CONCENTRATE 2 Lead None 85 None. Zinc do 75 Do. Lead . . . . 1 .5 units 95 95 95 60- None $5.00/oz. $0.20/oz. $0.40/lb. Silver 1 oz 85 Do. Gold . . 0.02 oz . . 1 oz Gold 0.02 oz 85 Do. Silver Copper TIN (75 pet), AV TREATMENT CHARGE, $635/t CONCENTRATE Tin .1 unit" 100 None. ' A unit equals 1 .0 pet or 22.05 lb 2 Treatment charge includes refining charge 3 Imperial smelting -furnace feed. " For every 0.1 pet tin above or below 75 pet, the unit deduction shall be decreased or increased by 0.01 unit, respectively. 27 TOTAL PRODUCTION COSTS Total production costs were determined for the 216 lead and zinc mines in market economy countries and are presented in tables in this section. Mines and deposits having combined surface and underground operations and primary copper operations containing lead and zinc as coproduct or byproduct commodities were not included. Costs are presented on a dollar-per- pound-metal basis and include mine, mill, smelting- refining. other, transportation, and total operating costs as well as taxes, byproduct credits, net cost, and total cost. Smelting-refining includes processing costs for the primary commodity while other costs include smelting- refining for coproduct and byproduct commodities. Transportation includes transportation costs of all concentrates to the smelter-refinery. Total operating cost is the total of all direct costs before taxes and byproduct credits. The taxes category includes all property, severance. State, and Federal taxes. Reve- nues from coproduct and byproduct commodities have also been computed and subtracted from total operat- ing cost to arrive at net cost. Net cost is the average out-of-pocket cost includ- ing all operating charges required to produce refined lead or zinc and any credit for byproduct production, but does not include recovery of capital or profit. It reflects the average lead or zinc price at which the mines in the country could break even by covering all production costs. A company may be willing to operate at this price temporarily if it believes the situation will improve in the near future. However, if the com- pany's outlook is bleak, it may temporarily shut down or permanently close the mine and shift its investment to a more profitable venture. An exception is State- owned or State-controlled mines, which may continue to produce at or belcw this price if the resulting losses are less than those incurred if the mine were closed. (If the mine were closed, the government may have to pay unemployment and other welfare benefits.) Gov- ernments also may need the foreign exchange revenues generated by the mine to import other materials needed in their country. The difference between the net cost and the total cost is that total cost includes recovery of capital and a profit on all investments at a 15-pct DCFROR. For some countries, only a small difference exists since most of the mines have been producing for many years and a large portion of the capital has been written off. For other countries, the difference is significant since new mines have recently begun production and large amounts of capita! have yet to be written off. LEAD Table 26 compares weighted-average production costs per pound lead for producing and undeveloped deposits in the United States and foreign countries. Costs for producing mines in the United States are comparable to foreign costs except that mining costs and byproduct credits are lower. Mine operating costs average $0.10 per pound lead in the United States compared with $0.17 for foreign countries because of the low cost, highly productive room-and-pillar mining methods used in the Missouri lerfd mines. However, foreign mines recover this U.S. cost advantage in by- product credits, which average twice those of domestic mines. As a result, net and total costs for U.S. and foreign mines are nearly equal. Operating costs for undeveloped deposits in the United States would average slightly higher than producing mines, with a total operating cost before taxes and byproduct credit only $0.04 higher per pound of lead. However, higher capital investments and lower byproduct credits result in a much higher total cost of $0.50 per pound versus $0.27 for producing mines. Taxes for undeveloped domestic deposits are higher than those for producing mines ($0.08 per pound compared with $0.03) because higher incomes are required to provide the stipulated 15 pet DCFROR; thus, aggregate tax payments are generally higher than for producing operations. Foreign undeveloped lead deposits have high operating costs mainly because of the high costs of Table 26. — Estimated total production costs for producing and undeveloped lead mines and deposits, January 1981 dollars per pound of lead recovered Mines- deposits Operating costs Mine Mill Smelting- refining' Other 2 Transport 3 Total Taxes" Byproduct credit Net cost Total cost D 'c<; J ; ng - net Foreign United States Total or average Undeveloped deposits Fofe>gn United States Total or average 13 9 SO .17 10 SO 06 06 $0 14 11 $0 05 03 $0 04 03 5 $0.45 5 34 $0.04 .03 $0.26 .13 $0 23 24 $0.30 .27 22 12 06 12 04 04 38 03 .17 .24 .28 3 5 36 12 13 08 15 11 08 04 11 03 ' 82 .38 .28 .08 39 .12 5 .72 .34 1 20 .50 8 26 11 13 06 08 64 20 .28 56 .87 ' Smelting and refining of lead only 2 Smelting and refining of all byproduct commodities 3 Total transportation cost for all concentrates from mill lo smeller and refinery 4 Includes all pfopenry. Slate Federal, and severance taxes plus any royalty Undeveloped deposits would require higher income in order to provide the stipulated 15 pet DCFROFt thus, estimated aggregate tax payments are generally higher for undeveloped deposits 5 Data do not equal total shown because of independent rounding 28 the Black Mountain lead-zinc-silver deposit in the Republic of South Africa. The deposit is a large- tonnage, low-grade deposit proposed for sequential development following depletion of reserves at the Broken Hill Mine. High operating costs, taxes, and a high capital investment (approximately $500 million) result in an average total cost of $1.20 per pound of lead for the three foreign deposits (average total costs without the Black Mountain deposit would drop to $0.55). It should be kept in mind that in many countries, special tax incentives and tax holidays can effectively reduce the tax burden and, consequently, lower the total costs determined for this study. ZINC Table 27 shows estimated total production costs per pound of zinc for producing and undeveloped zinc deposits. Mine operating costs for producing mines range from a low of $0.15 per pound in Spanish mines to a high of $0.31 in Mexican mines. The higher cost of underground mining in Mexico and Japan is due to the complex nature of the deposits and small capacity of many of the mines. As discussed earlier, the mining cost per metric ton of ore is lower in the United States than in foreign countries. However, owing to the lower grade of domestic deposits (3.28 pet zinc, compared with 5.77 pet in foreign countries) costs on a per- pound basis are higher. Mill operating costs range from a high of $0.25 per pound in Spain to a low of $0.05 per pound in Australia. Although U.S. mines had a $3 advantage over foreign mines on a per-metric-ton-ore basis (table 24), this advantage is offset by the lower grade of domestic mines. On a per-pound basis, U.S. and foreign mines are equal, at $0.10. The average cost to refine zinc ranges from $0.15 to $0.21 per pound of zinc. Japan is represented at the low end of this range as a result of a price support system whereby smelters can offer low terms on custom concentrate contracts because they are guaran- teed a price that is higher than the London Metal Exchange (LME) price for product sold to domestic manufacturers. U.S. refining costs average $0.20 per pound, $0.02 greater than foreign zinc refining costs. Other costs, including smelting and refining of lead and other byproduct commodities, range from $0.04 to $0.16 per pound of zinc. This wide range is due mainly to differences in byproduct grades, which result in additional smelting and refining charges. The mines with high costs in this category usually recover the added cost in the form of byproduct credits. Total operating costs before taxes and byproduct credits average $0.61 for producing mines. Mexico has the highest operating cost primarily due to high min- ing costs. However, this high cost is more than com- pensated for by high byproduct revenues ($0.77 per pound of zinc, principally from silver), which provide Mexico with the lowest net and total cost of any coun- try. High operating costs in Australia and Peru are also offset by high byproduct credits. Byproduct credits for foreign mines average $0.14 per pound greater than for U.S. mines. Net cost for producing mines averages $0.29 per pound, $0.46 in the United States and $0.28 in foreign countries, a difference of $0.18 per pound. As a result, U.S. mines have a long- run weighted-average total cost estimated at $0.58 per Table 27. — Estimated total production costs for producing and undeveloped zinc mines and deposits, January 1981 dollars per pound of zinc recovered Mines- deposits Operating costs Mine Mill Smelting- retining 1 Taxes 4 Other 2 Transport 3 Total Byproduct credit Net cost Total cost Producing mines: Australia Canada Germany, Fed. Rep. of Italy Japan Mexico Peru Spain Other Total or average United States Total or average Undeveloped deposits: Australia Canada India Ireland Other Total or average United States Total or average 7 $0.18 $0.05 $0 19 $0.16 $0.03 $061 $0.08 $0.56 $0.13 $0.20 13 .16 .10 18 .11 .06 .61 .02 .32 .31 .36 3 .17 .08 15 .04 .01 5 .46 .02 .26 .22 .24 4 26 .10 21 05 01 .63 .02 .21 .44 .50 8 .29 .11 15 04 .01 5 .59 .01 .20 5 .41 .44 15 .31 .10 20 .11 .04 5 .75 .10 .77 5 .09 16 14 .22 .10 17 06 .05 5 .59 .06 .36 5 .30 .35 4 .15 25 17 09 .03 .69 .01 30 .40 .51 25 .20 .09 19 .07 .02 5 .56 .05 .29 .32 .37 93 .20 .10 18 .10 .04 5 .61 .05 .37 5 .28 .33 16 .26 .10 20 .07 .02 .65 .04 .23 .46 .58 109 .20 .10 18 .09 .04 .61 .04 .36 .29 .35 5 .13 .04 19 .12 .05 .53 .15 26 5 .41 .61 20 .21 .08 17 .07 .11 .64 .13 .27 .50 .72 3 .40 .12 19 08 .03 5 .81 .10 .26 5 .66 .82 3 .25 .10 20 .04 .03 62 .19 .07 .74 1.02 8 .17 .09 18 .03 .05 52 .08 .18 5 .43 .59 39 .18 .07 18 .08 .07 58 .13 .24 5 .46 .66 38 .16 .08 18 .03 .06 5 .50 .18 16 5 .53 .86 77 .17 .07 18 .06 .06 5 .55 .15 .20 5 .49 .74 ' Refining of zinc only. 2 Smelting and refining of all byproduct commodities. 3 Total transportation cost for all concentrates from mill to smelter and refinery. 4 Includes all property, State, Federal, and severance taxes, plus any royalty. Undeveloped deposits would require higher income in order to provide the stipulated 15 pet DCFROR, thus, estimated aggregate tax payments are generally higher for undeveloped deposits. 5 Data do not equal total shown because of independent rounding. 29 pound. SO. 17 above the January 1981 LME price of zinc. Italy. Spain, and Japan also have average total costs higher than the January 1981 price. For most undeveloped deposits zinc could not be produced at a low enough cost to earn a 15-pct DCF- ROR. The total costs for these deposits average $0.74 per pound of zinc, more than double those of producing mines. Although mining and milling costs for un- developed deposits would be slightly less than for producing mines, this advantage would be lost in much lower byproduct credits (averaging $0.16 per pound less) and much higher capital costs. U.S. deposits, owing to lower ore grades, would average $0.86 per pound, $0.20 greater than foreign deposits. Taxes for undeveloped deposits would be greater than those for producing mines because higher incomes would be re- quired to provide a 15-pct DCFROR; thus, aggregate tax payments are generally higher than for producing operations. CAPITAL COSTS Capital costs reflect the total investment required for those deposits not producing at the time of the study to develop the mine, construct all facilities, and begin production. Capital costs for producing mines are not shown because some of the mines have been producing for many years and a large portion of the initial investment has been depreciated. Capital costs for exploration, acquisition, develop- ment, mine and mill plant and equipment, and infra- structure have been calculated for all deposits. For most deposits, capital costs for smelting and refining are included in the custom operating cost; these costs are not discussed in this section. Capital costs for developing and explored deposits, by type and size of operation, are shown in table 28. All costs are adjusted to January 1981 dollars and converted to dollars per annual metric ton of ore. The costs shown are averages for the deposits by size of operation; actual deposit costs may vary greatly depending on deposit location, characteristics of the ore body, and other factors. Capital costs were analyzed for 12 undeveloped surface deposits which have a weighted-average an- nual capacity of 1.9 million t of ore. The four deposits analyzed with annual ore capacities between 500,000 and 1 million t have a very high cost of $221 per annual metric ton of ore capacity because of the large capital requirements for developing three of the properties, which are in Alaska. A more reasonable total cost for less remote deposits of this capacity range would be $85 per annual metric ton of ore. Capital costs for surface operations with less than 500.000 t annual ore capacity would average $35 million; 500,000- to 1-million-t/yr capacity — $67 mil- lion (revised down from the high of $177 million in Table 28. — Capital costs of undeveloped lead and zinc deposits, January 1981 dollars per annual metric ton of ore Ore caDacitv Av ore Ex P l ° r a ,i ° n . ^ Q s '" Deposits capacity, 10 6 acquisition Surface: •05 4 0.5 to 1.0 4 1.0 to 2.0 1 >2.0 3 Total or av. Underground • 0.5 0.5 to 1.0. 1.0 to 2.0. . ■2 Total or av 78 .8 30 Plant and equipment Intra- struc- Total t/yr development Mine Mill ture 0.3 $56 $21 $29 $11 $117 0.8 50 42 61 68 221 1.7 28 11 29 11 79 5.5 4 16 19 11 50 12 1.9 14 19 25 18 76 35 .3 35 34 35 13 117 31 .7 29 30 30 9 98 6 1.4 35 27 27 83 172 6 3.1 24 20 42 l I 97 27 35 21 113 Alaska) ; 1 to 2 million — $134 million; and $275 mil- lion for deposits with annual capacity greater than 2 million t. Capital costs were also estimated for 78 unde- veloped underground deposits. High total capital cost per annual metric ton of ore for the 1- to 2-million- t/yr capacity range is a result of the remote location of many of the deposits, which would result in very high infrastructure costs. A more reasonable estimate of capital cost per annual metric ton ore capacity for this range would be $95 as opposed to $172. Average capital cost for underground operations with less than 500,000 t/yr ore capacity is $35 million; 500,000 to 1 million— $69 million; 1 to 2 million — $133 million; and for annual capacity greater than 2 million t, $300 million. 30 AVAILABILITY OF LEAD AND ZINC An economic evaluation was performed on each of the studied mines and deposits to determine the aver- age total cost of production over its entire producing life. The evaluation uses DCFROR techniques to de- termine the constant dollar long-run price of the operation's primary commodity so that total revenues (from the primary commodity and byproducts) are sufficient to cover all costs of production, discounted at a prespecified rate of return on all investments. An implicit assumption in each evaluation is that each deposit represents a separate corporate entity. The life of each property was determined by assuming that the property would operate at 100 pet of mine capa- city. The mine life covers only the demonstrated re- source level. All capital investments incurred 15 or more years before the cost date of the analysis (January 1981) are treated as sunk costs. Investments incurred dur- ing the prior 15 yr have the undepreciated balances entered as a capital investment in 1981. All subsequent investments, reinvestments, operating costs, and transportation costs are expressed in constant January 1981 dollars. Investment and operating schedules are determined as much as possible from published data or plans announced by the companies involved. For those deposits that have been explored, but where no plans to initiate production have been announced, a development plan was assumed. The preproduction period for these explored deposits allows for only the minimum engineering and development time necessary to initiate production. Additional time lags and poten- tial costs involved in filing environmental impact statements, receiving required permits, arranging fi- nancing, etc., are not accounted for in the analysis, but may be significant in the developed countries. The potential tonnage and the average total cost determined over the life of the operation for each of the mines and deposits evaluated in this study have been aggregated onto availability curves that illustrate the potential availability of the studied commodity at different cost levels. Availability curves are con- structed as aggregations of the total amount of the studied commodity potentially available from each of the evaluated mines and deposits, ordered from those having the lowest average total cost to those having the highest. The total potential availability of the commodity can be seen by comparing a projected constant-dollar long-run market price to the average total cost values shown on the availability curves. Availability curves were developed for 186 mines and deposits that were evaluated as operations with zinc as the primary commodity, 30 mines and deposits that were evaluated as operations with lead as the primary commodity, and 19 mines and deposits that were evaluated as copper operations with lead and zinc as significant byproducts. The .assignment of a par- ticular commodity as the primary product, generally based on that product providing the largest proportion of sales revenue at current market prices, is a neces- sary requirement of the evaluation process using a price determination model. In reality, owing to the complexity of lead-zinc ores, lead and zinc are often coproducts. In the case of a number of mines in Mexico and Peru, lead and zinc are byproducts of silver pro- duction. Moreover, the relationship between individual mineral commodities as coproducts and byproducts is dynamic, and can change as metal prices fluctuate in the marketplace. In cases where revenues from byproducts are able to cover total production costs (which are burdened against the primary product in the analysis), the curve will show the total cost of producing the primary product to be zero. This situation exemplifies the complexity of lead and zinc ores and underscores the effect that byproduct values (particularly silver) can have on the profitability of a mining operation. LEAD The 30 mines and deposits evaluated as primary lead operations in 10 market economy countries have an in situ demonstrated resource of 540.9 million t of ore, containing 26.2 million t of recoverable lead. Total availability curves illustrating potential availability of lead from primary lead mines and deposits in all market economy countries and the United States are shown in figure 13. The United States contains the largest recoverable lead resource, 18 million t (17.35 million in Missouri), accounting for 68.7 pet of the '-KJ ll.iliill .80 MARKET ECONOMY COUNTRIES - 70 - 60 J - 50 J - 40 - .30 _J ' 20 10 ^-^ 1 i i i i i i i i i - 2 5 5 7,5 10 12 5 15 17 5 20.0 22 5 25.0 UNITED STATES f 2 5 50 7.5 10.0 12.5 15.0 17.5 20 TOTAL RECOVERABLE LEAD. 10" t Figure 13. — Total recoverable lead from lead mines and deposits in market economy countries (including the United States) and the United States. 31 total, followed by Republic of South Africa with 3.8 million t (14.5 pet), and Morocco with 1.4 million t (.5.3 pet). These three countries account for 88.5 pet of the potentially recoverable lead from all of the mines and deposits evaluated with lead as the primary product. One explored South African deposit, with potential total recoverable lead of 1.9 million t at an estimated total cost of over SI per pound, is not shown on the market economy country curve. Approximately 43.8 million t of lead is potentially recoverable as a byproduct from mines and deposits evaluated as primary zinc operations (fig. 14). The largest individual sources of potential lead as a by- product of zinc arc Australia with 13.5 million t (30.8 pcO. Canada with 11.9 million t (27.2 pet), and the. United States with 5.6 million t (12.8 pet). Producing zinc mines account for 23.8 million t of lead, 54.4 pet of the total. Producing U.S. zinc mines account for only 169.000 t of lead. The 19 mines and deposits that were evaluated as primary copper operations can potentially produce 454.000 t of byproduct lead. The total amount of lead potentially recoverable from primary lead deposits, and as a byproduct of zinc and copper, is 70.4 million t. Total availability curves for all market economy countries and the United States, with a comparison of potentially recoverable lead from producing mines and from undeveloped deposits, are shown in figure 15. Of the 26.2 million t of lead estimated to be potentially recoverable from the 30 mines and deposits evaluated as primary lead operations. 22.1 million t (84.4 pet) is from producing mines and 4.1 million t (15.6 pet) is from undeveloped deposits. The nine mines in the United States account for 72.8 pet (16.1 million t) of the total potential tonnage from the producing mines evaluated for the study, and have a weighted-average total cost of SO. 27. The foreign production weighted- average cost is SO. 30. As a result, nearly all produc- ing mines in market economy countries are able to produce at or under the January 1981 lead price of SO. 34 per pound. The five undeveloped deposits in the United States have an estimated total cost of SO. 50, nearly double that of producing U.S. mines. The three non-U. S TOTAL RECOVERABLE Figure 14. — Total availability of lead as a byproduct of primary zinc mines and deposits in market economy coun- tries. :V r l i i i i i i i 8C I MARKET ECONOMY COUNTRIES - 70 - / eloped deposits - 60 1 ( 50 J 1 -- Producing mines f 3C ,1 ' IC _j 1 I r i i.l 1 1 1 1 75 17 5 20.0 22.5 IC UNITED STATES lUndeveloped deposits 60 - , I 3C - Producing mines 50 • 75 IOO 12.5 TOTAL RECOVERABLE LEAD. 10" t Figure 15. — Total recoverable lead from producing mines and undeveloped deposits in market economy countries (including the United States) and the United States. market economy country deposits costs are much higher with an estimated weighted-average total cost of $1.20 per pound. This average, however, is biased by the one South African deposit which has a total cost of well over $1 and is not included in the curve. Excluding this one deposit, the cost for the two re- maining deposits drops to $0.55 per pound. None of the undeveloped deposits has a total cost that is less than $0.34 per pound of lead. This indicates that the long- run market price for lead will have to rise above the current (1981) market level, or that the market prices of associated coproducts or byproducts will have to increase before any of these deposits could be de- veloped on a profitable basis. Technological changes, such as the recovery of cobalt and nickel from Mis- souri lead ores, enhanced recovery of zinc from lead furnace slag, or technological improvements in lead smelting to reduce process costs would also alter the potential profitability of new projects. Potential annual production levels for producing lead mines in market economy countries and the United States for 1981 to 1995 are shown in figure 16. The market economy country curve begins a gradual annual production decline in 1989, and begins to decline at a faster rate in 1994. Almost all the decline is from the potential depletion of non-U. S. mines as evidenced by the almost constant curve for the United States. However, it is doubtful that the demonstrated resource of these producing mines will decline at the rate indicated by the curve. Many of the lead mine operators in the world report their demonstrated 32 T i i i i i — $060 MARKET ECONOMY '-v.. - \~__^ - f n -5A __ — i ,.i J.. .._ 1 1. .' 1 | , t T 1 1 "■' UNITED STATES $035 " $0.30 - - $0 25 $0.20 1 1 1 1 1 1 1987 1989 YEAR Figure 16. — Potential annual availability of primary lead from producing lead mines in market economy countries (including the United States) and the United States, at va- rious production costs per pound. resources for only a few years ahead of their current mining position and increase or maintain their re- serves as mining continues. Also, in many cases demon- strated resources are increased each year as a result of ongoing exploration programs. The demonstrated re- source estimates that appear in this report are based on 1981 company reported data. However, there is a high probability that additional resources exist that will allow most of the currently producing mines to continue beyond the time frame of reported reserves. Similar curves for undeveloped lead deposits are shown in figure 17. Because startup dates for many undeveloped deposits are not known, construction of annual availability curves for them was based on the assumption that preproduction would begin in year N. For mines that were in the development stage in 1981, production shows up in the first few years of the curve. Potential annual production peaks rapidly and then begins to decline (an exception is the U.S. curve at a lead price of $0.35 per pound, which remains constant) . As mentioned previously, none of the de- posits can produce lead at an estimated long-run total cost of under $0.34 per pound. One U.S. deposit has an estimated long-run total cost of $0.35 per pound, but it is the only deposit that approaches the 1981 market price. Therefore, it is doubtful that more than three or four of these deposits will be developed in the near future. N Year preproduction development begins -^ \ MARKET ECONOMY COUNTRIES $0 90 ~$a75~ $0 55 $0.35 r / i / i i i S / 0\ \ N UNITED STATES $0 90 $0.65 $0 55 1 ; 1 ! 1 : I i 1 / / / 1 : $0 35 ' -' / ' '' / / 1 1 1 1 - N+l N + 3 N + 5 N+7 N + 9 N + ll N + 13 N + 15 YEAR Figure 17. — Potential annual availability of primary lead from undeveloped deposits in market economy countries (including the United States) and the United States, at various production costs per pound. ZINC At the demonstrated resource level, approximate- ly 141.1 million t of zinc metal is potentially recover- able from the 186 mines and deposits evaluated as primary zinc operations in 29 market economy coun- tries. The United States contains the largest poten- tially recoverable resource, 40.3 million t, which ac- counts for 28.6 pet of the total, followed by Canada with 30.2 million t (21.4 pet), and Australia with 23.2 million t (16.4). The combined total for these three countries amounts to 66.4 pet of the potentially re- coverable resource in market economy countries. The total availability curves illustrating potential avail- ability of zinc from primary zinc mines and deposits in all market economy countries, the United States, Canada, and Australia are shown in figure 18. Note that the highest total zinc production cost on any of the curves is $1.50 per pound. Three explored deposits (one each in Australia, Canada, and India) with total zinc production costs estimated at higher than $1.50 per pound and a combined potential production of 1.8 million t, are not shown on the curves. An additional 4.3 million t of zinc is potentially available from 21 mines and deposits evaluated as primary lead opera- tions, with 58 pet (2.5 million t) of this potential tonnage in the United States (fig. 19). 33 I 5C 1.40 1. 30 1.20 1.10 1.00 .90 ec .70 .60 - - .10 MARKET ECONOMY COUNTRIES — 20 30 40 SO 60 70 80 90 IOC 110 I2C I3C 140 1.40 1.20 ^ ..... 1 - :: - v - K - U. -: S^ . . 1 i I . L. :: J UNITED STATES J I I L -J I I L 16 20 24 28 32 36 40 44 ~\ 1 1 — i 1 — i 1 — i r CANADA 4 6 6 J I I L J I I I I 1 I L 20 22 24 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 TOTAL RECOVERABLE ZINC. 10 e t Figure 18. Canada), the — Total recoverable zinc from market economy countries (including the United States, Australia, and United States, Australia, and Canada. Figure 19. — Total availability of zinc as a byproduct of primary lead mines and deposits in market economy coun- tries (including the United Slates) and the United States. As shown in figure 20, another 8.3 million t of zinc is potentially recoverable as a byproduct from the 19 mines and deposits evaluated as primary copper opera- tions with Canada accounting for 4.6 million t (55 pet) of the total; none of this potential tonnage is in the United States. The total tonnage of potentially recoverable zinc from all three sources (primary zinc, primary lead, and primary copper) amounts to 153.7 million t, with 42.7 million t (27.8 pet of the total) from U.S. demonstrated resources. & 1 40 o. o. o I 1 ! 1 1 I I i [ o D ■ Q. , — l 01 | o ^J o ) °. 60 O J \ ■ i i i i i i i /I maiii i /ii. Figure 20. — Total availability of zinc as a byproduct of primary copper mines and deposits in market economy countries. 34 Total availability curves for all market economy countries and the United States, with a comparison of tonnage from producing mines and from undeveloped deposits (explored deposits and developing mines), are shown in figure 21. Of the 141.1 million t of primary zinc estimated to be potentially recoverable from market economy countries, 43.8 pet (61.8 million t) is from producing mines and 56.2 pet (79.3 million t) is from undeveloped deposits. The 109 producing mines evaluated as primary zinc mines have a weighted-average estimated total cost of $0.35 per pound of zinc (see table 27). Total potential zinc production from these mines amounts to 61.8 million t, with 44.3 million t (72.5 pet of the total) potentially available at an estimated cost level (including a 15-pct DCFROR) below the January 1981 market price of $0.41 per pound. Approximately 11 million additional metric tons of zinc can potentially be recovered from 17 producing mines that can produce at a break-even cost of $0.41 per pound (meaning that they can cover all operating costs and recover capital at a 0-pct DCFROR) . This means that 81 of the 109 producing zinc mines could potentially break even at January 1981 estimated costs and prices. Producing mines that cannot cover production costs at a zinc price of $0.41 I I 1 1 I 1 1.40 MARKET ECONOMY COUNTRIES J ~ 1 20 - j 1.00 , r Undeveloped deposits^ .80 " /V .60 _ r r , / ~ J JProducing mines 40 J J 1 _ rJ - J -> .20 1 I 1 1 1 ! 20 30 40 50 60 70 80 UNITED STATES Producing mines j- _, 'Undeveloped deposits J L TOTAL RECOVERABLE ZINC, 1 0» I Figure 21. — Total recoverable zinc from producing mines and undeveloped deposits in market economy countries (including the United States) and the United States. per pound may eventually have to be closed if prices do not improve (operations in some countries receive a subsidy from the government and therefore can con- tinue to produce at lower zinc prices). A total of 79.3 million t of zinc is potentially recoverable from the 77 undeveloped deposits evaluated in market economy countries with a weighted-average estimated total cost of $0.74 per pound (table 27) . Only 1.85 million t (2.3 pet of the total) is estimated to be recoverable at a total cost below the January 1981 market price of $0.41 per pound of zinc. The curve for the United States shows that 4.1 million t of zinc is potentially recoverable from the 15 zinc mines that were producing in January 1981, which is only 10.3 pet of the total U.S. recoverable resource of 40.3 million t, and is less than 7 pet of the 61.8 million t of zinc potentially recoverable from produc- ing mines in all market economy countries. The weighted-average total cost of production for these 15 mines is $0.58 per pound of zinc (ranging from $0-00 to $0.74) in January 1981 dollars. From demon- strated resources in 1981, only 454,000 t of recoverable zinc (11 pet of total recoverable zinc from U.S. pro- ducers) is potentially recoverable below a long-run total cost of $0.41 per pound of zinc. This cost situa- tion has likely contributed to the number of zinc operations closing or going on a temporary standby status during 1981 and 1982. The evaluations for the 38 undeveloped deposits resulted in potential produc- tion of 36.1 million t of zinc with a weighted-average total cost of $0.86 per pound of zinc in constant January 1981 dollars. This situation would make most of these deposits uneconomic under present economic conditions. A shift in the price structures of zinc, lead, or silver would alter this situation, however. Potential annual production levels for producing zinc mines in market economy countries and the United States for 1981 to 1995 are shown in figure 22. As with the curves for lead mines, the curves indicate a fairly rapid depletion rate, which is based more on the criteria of this study rather than what will prob- ably occur. Potential annual production levels for undeveloped zinc deposits in market economy countries and the United States are shown in figure 23. If preproduction of all undeveloped deposits were to begin in year N, production would peak in the seventh year and remain constant through year N + 14. Only three of the un- developed deposits evaluated for this study have esti- mated total production costs that are less than the January 1981 market price ($0.41 per pound) for zinc. Actual development of these deposits will depend on the level of demand and the associated market prices for zinc, lead, silver, copper, gold, and other coproducts or byproducts of zinc production. The foregoing availability analyses can be con- cisely summarized by the use of tables showing poten- tial recoverable zinc and lead, by country, with the associated weighted-average estimated long-run aver- age total costs of production. These data are presented in tables 29 through 34. 35 * x : sr ; MARKET ECONOMY COUNTRIES $040 $C20 2? - .— , 1 , UNITED STATES / "A v \ \ \ - J" — $0 45 - "-^^ $0 35 Figure 22. — Potential annual availability of zinc from pro- ducing zinc mines in market economy countries (including the United States) and the United States, at various produc- tion costs per pound. 1 1 1- 1 1 MARKET ECONOMY COUNTRIES / / N Year preproduction / development beqms / / l _ $1 50 $0.80 $060 - '/ ' $0.50 ~t*0£ $0 40 """ i i N+7 N+9 YEAR N + 13 N + 15 Figure 23. — Potential annual availability of zinc from un- developed deposits in market economy countries (including the United States) and the United States, at various produc- tion costs per pound. Table 29. — Comparison of estimated long-run average total costs of potential zinc metal production from primary zinc mines and deposits Producing mines Undeveloped deposits Potential production 10 3 t Cost' Potential production. 10 3 t Cost' Producing mines Undeveloped deposits Potential production. 10 3 t Cost' Potential production, 10 3 t Cost' Akgena Argentina Austna BoJr/ia Braz Burma Canada F "land France Germany. Fed Rep of Greece Gree^iano Honou'as India Ireland 1447 428 6 74167 3180 148 6 709 1 943 17.128 8 6667 349 8 1 861 6 6162 378 6 404 2 1 .055 2 2.540 5 W W $0 20 W 28 W W 36 43 57 24 00 W W W 43 NAp NAp 15.7722 NAp NAp 605.3 NAp 13.1184 NAp 202 1 NAp NAp NAp NAp 2.171 1.1790 NAp NAp $0.61 NAp NAp W NAp 72 NAp 68 NAp NAp NAp NAp 82 1 02 Italy Japan Mexico Morocco Namibia Peru Portugal South Africa. Rep ot Spam Sweden Turkey Zaire Zambia . . . 9273 2.312.9 4,946.9 NAp 2738 5,346.6 2,3053 NAp 2.2035 1,697 1542 2.9458 327 8 $0 50 .44 .16 NAp W .35 W NAp 51 .35 W w w 583 NAp 590.9 759 NAp NAp NAp 7,751.5 1,592.2 NAp NAp NAp NAp Total or average United States Grand total or av 57,702 7 4,139 7 58 43. r ? 8 36,1385 61.842 4 .34 =79,2554 NAp Not applicable W Withheld, company proprietary data ' Weighted-average total cost ot production per pound ot zinc 1 Data do not add to total shown because of independent rounding W NAp W W NAp NAp NAp W $0 82 NAp NAp NAp NAp 86 74 36 Table 30. — Comparison of estimated zinc metal production as a byproduct from lead mines and deposits at the estimated long-run average total costs of primary lead production Producing mines Undeveloped deposits Producing Potential production, 10 3 t mines Cost' Undevelope< Potential production, 10 3 t i deposits Potential production, 10 3 t Cost' Potential production, 10 3 t Cost' Cost 1 Australia France 488.5 31.8 NAp 20.6 42.1 W W NAp W W NAp NAp 129.3 10.5 NAp NAp NAp W W NAp South Africa, Rep. of Sweden Total or average United States 628.4 163.3 W W 297.7 NAp W NAp Mexico Morocco 1,374.7 2,208.2 $0.28 437.5 246.5 $0.50 Namibia. Grand total or av 2 3,582.8 .28 684.0 .87 NAp Not applicable. W Withheld, company proprietary data. 1 Weighted-average total cost of production per pound of lead. 2 Data do not add to total shown because of independent rounding. Table 31 . — Comparison of estimated zinc metal production as a byproduct from copper mines and deposits at the estimated long-run average total costs of primary copper production Producing mines Undeveloped deposits Producing Potential production, 10 3 t mines Cost 1 Undevelopec Potential production, 10 3 t i deposits Potential production, 10 3 t Cost 1 Potential production, 10 3 t Cost 1 Cost 1 Australia Canada Finland Japan 616.6 4,477.6 35.4 649.2 87.0 W $0.25 .69 W W 159.1 81.7 NAp NAp NAp W W NAp NAp NAp Peru South Africa, Rep. of Sweden Turkey Total or average NAp 131.4 156.1 NAp NAp W W NAp 1,267.3 NAp NAp 6505 W NAp NAp $1.06 Norway 6,153.3 $0.42 2 2,158.7 1.14 NAp Not applicable. W Withheld, company proprietary data. 1 Weighted-average total cost of production per pound of zinc. 2 Data do not add to total shown because of independent rounding. Table 32.— Comparison of estimated long-run average total costs of potential lead metal production from primary lead mines and deposits Producing mines Undeveloped deposits Producing Potential production, 10 3 t mines Cost 1 Undevelopec Potential production, 10 3 t deposits Potential production, 10 3 t Cost 1 Potential production, 10 3 t Cost 1 Cost 1 Australia Canada France Mexico Morocco 708.4 35.8 170.1 136.8 1,281.4 375.8 W W W w $0.26 W NAp NAp NAp 211.3 82.7 NAp NAp NAp NAp W W NAp South Africa, Rep. of Spain Sweden Total or average United States 1,905.4 83.5 . .. 1,307.7 6,004.9 . .. 16,104.9 W W $0.33 .27 .28 1.874.3 NAp NAp 2,168.3 1,927.7 4,095.9 W NAp NAp $0 50 Namibia. Grand total or av 22,109.9 .87 NAp Not applicable. W Withheld, company proprietary data. 1 Weighted-average total cost of production per pound of lead. NOTE. — Data do not add to totals shown because of independent rounding. Table 33.— Comparison of estimated lead metal production as a byproduct of primary zinc mines and deposits at the estimated long-run average total costs of primary zinc production Producing mines Undeveloped deposits Potential production, 10 3 t Cost 1 Potential production, 10 3 t Cost 1 Algeria Argentina Australia Austria Bolivia Brazil Burma Canada Finland France Germany, Fed. Rep. of Greece Greenland Honduras India Ireland 35.1 367.5 5,878.8 84.5 19.0 NAp 134.0 7,745.7 21.2 18.0 404.5 484.0 120.8 223.0 389.6 583.1 W W W W $0.28 NAp W .36 W .57 .24 .00 W W W .43 NAp NAp 7,585.0 NAp NAp 181.1 NAp 4,107.7 NAp 59.4 NAp NAp NAp NAp 1,001.1 225.8 NAp NAp $0.61 NAp NAp W NAp .73 NAp .68 NAp NAp NAp NAp .82 1.02 Producing mines Undeveloped deposits Potential production, 10 3 t Cost 1 Potential production, 10 3 1 Cost 1 Italy Japan Mexico Morocco Namibia Peru Portugal South Africa, Rep. of . Spain Sweden Turkey Zambia 311.7 361.4 2,132.4 NAp 79.0 1,970.8 1,014.1 NAp 787.5 336.4 4.8 158.4 $0 50 .44 .16 NAp .43 .35 W NAp .50 .35 W W 28.2 NAp 697.9 13.9 NAp NAp NAp 434.2 172.6 NAp NAp NAp W NAp W W NAp NAp NAp W W NAp NAp NAp Total or average 23,665 3 United States 168.5 .44 14,506.9 5,440.5 $0.72 Grand total or av 2 23,833.7 .33 19,947.4 .68 NAp Not applicable. W Withheld, company proprietary data. 1 Weighted-average total cost of production per pound of zinc. 2 Data do not add to total shown because of independent rounding 37 Table 34.— Comparison of estimated lead metal production as a byproduct from copper mines and deposits at the estimated long-run average total costs of primary copper production Producing mines Undeveloped deposits Producing Poti produi 10' t mines Cost' itial non, deposits Pott? production, Cost' Potential production, 10' t Cost' Cost' Austrai;a Canada 198.3 71.0 W W 8.5 NAp W NAp Namibia Total or average 107.6 685 W w NAp NAp NAp NAp 4454 $0.38 85 W NAp Not applicac e v\ Withheld, company proprietary data 1 Weighted-ave-age total cost of production per pound of copper IMPORTANCE OF SILVER AS A BYPRODUCT OF LEAD AND ZINC PRODUCTION The most important byproduct associated with the production of lead and zinc is silver. The 186 mines and deposits evaluated as zinc operations con- tain approximately 3.3 billion tr oz of recoverable silver, and the 30 mines and deposits evaluated as lead operations account for 468 million tr oz. The 19 mines and deposits evaluated as copper operations with lead and zinc as byproducts account for an additional 242 million tr oz of recoverable silver. Approximately two-thirds of total world silver resources are asso- ciated with copper, lead, and zinc deposits (11). Re- coverable silver as a byproduct of potential leat zinc production, by country, is shown in table 35. The impact of byproduct silver on the economics of lead and zinc availability is illustrated in figures 24 and 25. Figure 24 shows potential recoverable lead Table 35.— Total recoverable silver as a byproduct of potential lead and zinc production, thousand troy ounces Producing mines Undeveloped deposits Pnmary lead Primary zinc Primary lead Primary zinc Aae-a NAp 910 NAp 25.959 Austrana 37.703 360.192 Bolivia NAp 16.266 NAp 9.857 Ha 120 476,626 NAp 7,683 =-a-:e 14 250 8.373 Germany Fed Rep ot NAp 17.750 Greece NAp 48.078 Greenland NAp 2.819 Honduras NAp 25.447 India NAp 15.456 fcnlmicl NAp 10233 haty . NAp 1 1 .203 ,a=a- NAp 55.945 NAp NAp NAp NAp NAp NAp NAp NAp NAp NAp NAp NAp NAp NAp NAp NAp NAp NAp 373.928 NAp NAp 268.520 NAp 8,439 NAp NAp NAp NAp 28.282 NAp 853 NAp Mexico Morocco Namibia . Peru. Portugal South Africa, Rep. of . Spain. Sweden Zaire Zambia Total United States Grand total Total . . 2,443,819 Producing mines Undevelop Bd deposits Primary Primary Primary Primary lead zinc lead zinc 25,388 508,117 15,185 165,220 19,081 NAp 4,945 6,310 14,593 1,962 NAp NAp NAp 252,150 NAp NAp NAp 109,132 NAp NAp 82,707 NAp 44,704 37,663 1,385 20,250 NAp 21,737 8,741 39,190 NAp NAp NAp 13.968 NAp NAp NAp 690 NAp NAp 203,968 2,038,256 64,834 910,952 191,384 10,210 7,282 328,657 '395,354 '2,048,465 72,116 '1,239,610 1,311,726 NAp Not applicable ' Data do not add to totals shown because of independent rounding /r , i ■■■ - 5 _f JL • Figure 24, — Total availability of lead from mines and de- posits in market economy countries with byproduct silver at varying prices — — 1 1 1 1 — 1 i r/lr - J uyj -* r'i f / -J r i ' Figure 25. — Total availability of zinc from mines and de- posits in market economy countries with byproduct silver at varying prices. 38 from lead mines and deposits in market economy countries with different prices for byproduct silver, and figure 25 illustrates the effect of different silver prices on the availability of zinc from primary zinc mines and deposits. These curves were constructed by holding all costs and revenues constant except for the revenues for byproduct silver at varying prices. It should be kept in mind that these are long-run analyses and that the silver price variations are long-run prices in constant January 1981 dollars, and do not reflect short-run fluctuations in the price of silver. In order to effect the shifts in the curves shown in figures 24 and 25, any price change of silver would have to be sustained over a number of years. The results of the analyses illustrated in the these figures are presented in tabular form, in tables 36 and 37, which show the weighted-average total costs of lead and zinc production for producing mines and un- developed deposits in market economy countries with byproduct silver prices at $5, $20, and $50 per tr oz. These weighted-average total costs can be compared with the costs presented in tables 29 and 32 which were determined with a byproduct silver price of $10 per troy ounce. It is not surprising that the greatest impact of byproduct silver revenues appears in coun- tries with the largest silver resources, namely Aus- tralia, Mexico, and Peru. This analysis further under- scores the competitive advantage enjoyed by the major producers of zinc with high byproduct silver content compared with most of the U.S. zinc producers in Tennessee, which have no byproduct silver at all. Table 36. — Weighted-average total cost of production per pound of lead with various prices per troy ounce of byproduct silver $5 $20 $50 Producing Undeveloped Producing Undeveloped Producing Undeveloped mines deposits mines deposits mines deposits Australia W NAp W NAp W NAp Canada W NAp W NAp W NAp France W NAp WWW NAp Mexico W W W W W W Morocco $0.29 W $0.22 NAp $0.12 W Namibia W NAp WWW NAp South Africa, Rep. of W W W NAp W W Spain W NAp W NAp W NAp Sweden .34 NAp .31 NAp .24 NAp United States .28 $0.50 .26 $0.48 .22 $0.46 Average .31 .91 .24 .80 19 .63 NAP Not applicable. W Withheld, company proprietary data. Table 37.— Weighted-average total cost of production per pound of zinc with various prices per troy ounce of byproduct silver $5 $20 $50 Producing Undeveloped Producing Undeveloped Producing Undeveloped mines deposits mines deposits mines deposits Algeria W NAp W NAp W NAp Argentina W NAp W NAp W NAp Australia $0.26 $0.65 $0.15 $0.51 $0.06 $0.31 Austria W NAp W NAp W NAp Bolivia .52 NAp .26 NAp .24 NAp Brazil W W W W W W Burma W NAp W NAp W NAp Canada .41 .76 .26 .64 .06 .43 Finland .45 NAp .38 NAp .24 NAp France .60 .77 .50 .49 .30 .01 Germany, Fed. Rep. of .26 NAp .19 NAp .09 NAp Greece .01 NAp .00 NAp .00 NAp Greenland W NAp W NAp W NAp Honduras W NAp W NAp W NAp India W .85 W .76 W .58 Ireland .43 1.02 .42 1.02 .41 1.02 Italy .53 W .48 W .48 W Japan .48 NAp .36 NAp .22 NAp Mexico .37 W .05 W .00 W Morocco NAp W NAp W NAp W Namibia W NAp W NAp W NAp Peru .44 NAp .22 NAp .07 NAp Portugal W NAp W NAp W NAp South Africa. Rep. of NAp W NAp W NAp W Spain .52 W .47 W .36 W Sweden .40 NAp .29 NAp .16 NAp Turkey W NAp W NAp W NAp United Sates .58 .88 .57 .82 56 .72 Zaire ' W NAp W NAp W NAp Zambia W NAfs W NAp W NAp Average .40 .78 .27 .69 .16 .56 NAp Not applicable W Withheld, company proprietary data. 39 DEMAND FOR LEAD AND ZINC The long-run situation for the lead industry is more complicated than that for zinc, since primary lead producers not only face stiff competition from each other, but from the large and growing secondary industry as well. Total world primary lead demand is forecast to increase at an annual rate of 2.4 pet per year through 2000, with a cumulative primary demand of 77 million t over the 20-yr period. Total demand for lead, including secondary lead, is forecast to in- crease at an annual rate of 2.8 pet (3.2 pet for second- ary leadV For the United States, total demand is fore- cast to grow at an annual rate of 1.8 pet. with primary lead demand increasing at a 1.5-pet annual rate and demand for secondary lead growing at an annual rate of 2.0 pet. The part of U.S. demand met by secondary lead is expected to approach 60 pet by 2000. as opposed to slightly over 50 pet at the present time, owing to gradual structural and technological changes in the industry and a relative increase in nondissipative end uses for lead (S). Based on this forecast, cumulative demand for primary lead in the United States between 1981 and 2000 is estimated to be 13.8 million t. Current demonstrated resources estimated to be recoverable in the United States at long-run produc- tion costs under the 1981 market price of $0.34 per pound amount to 16.18 million t, which is well above the estimated cumulative demand of 13.3 million t. Total recoverable resources in market economy coun- tries amount to 70.4 million t (41.1 million t poten- tially available at 1981 market prices), and cumulative demand for primary lead through 2000 (including central economy countries) equals 77 million t. As with zinc resources, demonstrated resource estimates for lead have increased significantly over the past 20 yr. The 1962 resource estimate for lead (12) was 45.2 million t for the total world, with 17 million t in the United States. These resources were deemed adequate to satisfy demand for 20 yr. The World Bank-LME lead price forecast (IS) predicts constant 1981 dollar lead prices of $0.29 per pound in 1985. $0,358 in 1990, and $0.38 in 1995. The $0.38-per-pound estimate for 1995, if reasonably accu- rate, would indicate that 84 pet of the 26.4 million t of lead metal from the mines and deposits evaluated as primary lead operations could potentially be produced and earn a 15-pct DCFROR for each respective opera- tion. The United States, with the largest low-cost re- source, appears to have a comparative advantage over the rest of the world industry. Total world primary zinc demand is estimated to grow by 2.5 pet a year through 2000 U), which is slightly higher than the 2.2-pct annual growth rate projected for the U.S. demand. This would make cumu- lative primary demand from 1981 through 2000 equal to 23 million t in the United States and 143 million t for the total world. Because the demonstrated recover- able resources of zinc in market economy countries alone equals almost 154 million t, the current zinc resource is adequate to meet demand through the year 2000 At 1981 market prices, however, the available economic tonnage of zinc from market economy coun- tries equals only 56.1 million t, of which 2.7 million t is in the United States. Superficially, this discrepancy between cumulative demand and lower cost potential supply indicates that the price for zinc, in real terms, would have to go up dramatically in order to satisfy cumulative demand through 2000. This can be quite misleading, however, owing to the dynamic nature of resource estimates. This study is based on a static, conservative resource estimate for zinc based on 1981 data. No effort has yet been made to project potential zinc resources that may exist in 2000. Zinc resource estimates have increased over time as new deposits have been discovered and as explora- tion programs continue at existing mines. For ex- ample, zinc resources in 1962 (lb) were estimated to equal 77.1 million t (11.1 million in the United States). This resource equaled a 17-yr supply of zinc at 1962 consumption rates. Current resource estimates are deemed sufficient to provide at least a 20-yr supply. The point is that these resource estimates are based on current data, and are not meant to indicate that we are going to run out of a given commodity in 20 yr. It is not unlikely that resource estimates for zinc in 2000 will indicate that resources are also deemed sufficient for a 20-yr supply of zinc. The key results of this study are not so much the aggregate tonnages presented, which are going to change on an almost annual basis anyway, but the relative distri- bution of resources between countries and the relative costs of production associated with these tonnages. The cun-ent lower cost producers will probably con- tinue to be the low-cost producers, particularly if any" significant new tonnage increases of zinc resources over the next 20 yr or so are additions to existing mines. This would suggest that the U.S. position in zinc production will remain weak or will weaken fur- ther owing to the small percentage of low-cost zinc potentially available from producing mines. Although the United States contains the largest potentially recoverable zinc resource in market economy countries, slightly less than 11 pet of this resource is from producing mines, and the balance from undeveloped deposits will be much higher cost to exploit than the zinc resources in other market economy countries. In summary, the results of the analyses indicate that zinc resources in market economy countries should at least be adequate to satisfy projected demand for primary zinc through the balance of this century. The study suggests that the comparative disadvantage faced by the U.S. zinc industry will probably intensify owing to the relative quantity of lower cost zinc re- sources in other countries, especially Canada, Aus- tralia, and Mexico. One World Bank price forecast for zinc (13) predicts that, in constant 1981 dollar terms, the price of slab zinc on the London Metal Exchange (LME) will drop to $0.36 per pound in 1985, and then rise to $0,419 in 1990. and to $0.45 in 1995. Such a gradual rise in constant dollar prices for zinc would indicate that the industry will remain fiercely com- petitive throughout the balance of the century, and profitability will remain an elusive goal for many pro- ducers if the long-run constant dollar price for zinc remains at such a low level. 40 CONCLUSIONS The demonstrated resources of lead and zinc ore comprising 235 mines and deposits in market economy countries evaluated for this study amount to approxi- mately 4.3 billion t of ore containing 221 million t of zinc and 97 million t of lead. Of these amounts, ap- proximately 154 million t of zinc and 70 million t of lead are estimated to be recoverable. These demon- strated resources are sufficient to satisfy projected demand through the balance of the century. Further- more, as new lead and zinc deposits are discovered, and as exploration programs at existing mines con- e, it is likely thai itrated resource estimates will continue to increase over time. Low prices for both lead and zinc have served to make the financial position of producers more pre- carious over the past several years. Several marginal producers have shut down permanently and other high- cost producers will likely follow suit over the next few years if prices continue to remain at low levels. The 109 producing mines evaluated as primary zinc mines have a weighted-average estimated total production cost (including a 15-pct DCFROR) of $0.34 per pound. Total potential zinc production from these mines amounts to 61.8 million t, with 44.8 million t potentially available at estimated cost levels below the January 1981 market price of $0.41 per pound. The United States appears to be at a competitive disadvantage, with only 454,000 t of zinc potentially recoverable below a long-run total cost of $0.41 per pound, and a weighted-average estimated total cost of $0.58 for the 4.14 million t estimated to be recoverable from U.S. producing mines. A total of 79.3 million t is potentially recoverable from the 77 undeveloped zinc deposits evaluated in market economy countries with a weighted-average total cost of $0.74 per pound. Only 1.85 million t (2.3 pet of the total) is estimated to be recoverable below $0.41 per pound. The 36.1 million t of zinc potentially recoverable from undeveloped deposits in the United States has an estimated weighted-average total cost of $0.86 per pound. It is likely that U.S. dependence on imported slab zinc will continue to increase in the future, although stable supplies are virtually assured from Canada, Australia, and Mexico. The cost picture for producing lead mines in the United States looks somewhat brighter. Nine U.S. mines account for 72.8 pet of the total potential ton- nage from the 22 producing mines evaluated for this study, and have a weighted-average estimated total cost of $0.27 per pound. The non-U. S. producing mines have a weighted-average total cost of $0.30 per pound. The five undeveloped U.S. deposits evaluated appear to have a minor cost advantage over the three non- U.S. deposits, although none of the eight deposits has an estimated long-run average total cost that is less than the January 1981 market price of $0.34 per pound. REFERENCES 1. U.S. Geological Survey and U.S. Bureau of Mines. Principles of a Resource/ Reserve Classification for Miner- als. U.S. Geol. Surv. Circ. 831, 1980, 5 pp. 2. Clement, G. K., Jr., R. L. Miller, P. A. Seibert, L. Avery, and H. Bennett. Capital and Operating Cost Estimating System Manual for Mining and Beneficiation of Metallic and Nonmetallic Minerals Except Fossil Fuels in the United States and Canada. BuMines Spec. Publ., 1980, 149 pp.; also available as STRAAM Engineers, Inc. Capital and Operating Cost Estimating System Handbook — Mining and Beneficiation of Metallic and Nonmetallic Minerals Except Fossil Fuels in the United States and Canada (contract J0255026), 1977, 374 pp.; available from U.S. Government Printing Office, stock No. 024- 004-0215-6. 3. Woodbury, W. D., and J. A. Rathjen. Lead. BuMines Mineral Commodity Profile, 1983, 17 pp. 4. Jolly, J. H. Zinc. BuMines Mineral Commodity Pro- file, 1983, 18 pp. 5. Davidoff, R. L. Supply Analysis Model (SAM) : A Minerals Availability System Methodology. BuMines IC 8820, 1980, 45 pp. 6. Stermole, F. J. Economic Evaluation and Investment Decision Methods. Investment Evaluations Corp., Golden, CO, 1974, 443 pp. 7. Kilgore, C. C, S. J. Arbelbide, and A. A. Soja. Lead and Zinc Availability — Domestic. A Minerals Availability Program Appraisal. BuMines IC 8962, 1984, 30 pp. 8. Jensen, M. L., and A. M. Bateman. Economic Mineral Deposits. 3d ed., 1981, 593 pp. 9. Brown, D. H., and A. Lust. World Directory: Lead and Zinc Mine and Metallurgical Works. MRI 79/5, Mineral Policy Sector, Internal Report. Energy, Mines and Resources of Canada, 1979, 78 pp. 10. Cotterill, C. H., and J. M. Cigan. Survey of World Lead and Zinc Production. Paper in AIME World Sym- posium on Mining and Metallurgy of Lead and Zinc. AIME, New York, v. 2, 1970, p. 15. 11. U.S. Bureau of Mines. Silver. Ch. in Mineral Com- modity Summaries 1984. Pp. 140-141. 12. Moulds, D. E. Lead. Ch. in Mineral Facts and Prob- lems, 1965 Edition. BuMines B 630, 1965, pp. 489-509. 13. The World Bank. Biennial Review of Commodity Price Forecasts, Volume 3: Metals and Minerals. The World Bank, Washington, DC, 1983, 244 pp. 14. Schroeder, H. J. Zinc. Ch. in Mineral Facts and Problems, 1965 Edition. BuMines B 630, 1965, pp. 1083- 1104. 15. Purser, W. F. C. Metal Mining in Peru, Past and Present. Praeger Publ., New York, 1971, 329 pp. 41 APPENDIX —GEOLOGIC CHARACTERISTICS OF MAJOR LEAD AND ZINC DEPOSITS IN MARKET ECONOMY COUNTRIES AUSTRALIA Of the 15 Australian deposits evaluated for this report, 6 contain significant amounts of recoverable copper and all of the deposits have silver present in important recoverable quantities. The major Aus- tralian lead and zinc deposits occur in two main dis- tricts: Mount Isa and Broken Hill. Mount Isa is the larg- ralian lead-zinc deposit, located in west- central Queensland. Mineralization occurs as syngene- ic deposition in the Urquhart shale formation of the Lower Proterozoic Mount Isa Group sediments. Ga- lena, sphalerite, and pyrite form closely spaced, con- cordant bands grouped to form 14 distinct ore bodies in an en echelon pattern. The nearby Dugald River, Hilton, and Lady Loretta deposits are genetically similar to the Mount Isa deposit. The McArthur River deposit is a large explored deposit located 100 km south of the Gulf of Carpen- taria in the Northern Territory. The stratiform de- posit is unme*amorphosed and occurs near the center of the McArthur Group, a sequence of dolomitic sedimentary rocks of Middle Proterozoic Age. Fine- grained sphalerite, galena, and other sulfides occur as minations in carbonaceous, potassic, dolomitic, and pyritic shales. A small amount of silver is asso- ciated* with the galena and marcasite; arsenopyrite and chalcopyrite are also present. This deposit may possibly be related genetically to the Mount Isa-type deposits. The Broken Hill district in western New South Wales occurs within the Willyanna Complex, a system of foliated metamorphic rocks of the Proterozoic Era. The deposit is stratiform type with lens-shaped ore bodies containing sphalerite and galena with minor pyrrhotite and marcasite. Ore is currently extracted by three operations in the Broken Hill deposit: North Broken Hill Holdings Ltd., Vaw Broken Hill Consoli- dated Ltd., and Zinc Corporation mines. Volcanogenic massive sulfide deposits are found at Woodla.n, N ith Wales; Teutonic Bore in ern Australia; Que River and Rosebery in Tas- mania; and Benambra in Victoria. The C.S.A. deposit in the Cobar mining district of western New South •s is also a massive sulfide deposit localized in siltstones of the Upper Silurian age Cobar Group sedi- ments, which lie on the west limb of an extensively folded anticlinal structure. CANADA A total of 42 Canadian lead and zinc deposits were evaluated for this study. These deposits fall into three general geological classifications: limestone replace- ment, shale-hosted, and volcanogenic massive sulfide, stone replacem* eferred to as Missis- sippi Valley type df-r, onsist oi lime- stone or dolom formations that have been mineralized by mineral-bearing fluids. Major ore min- erals are galena and sphalerite with minor occurrences of silver. The Pine Point. Prairie Creek, Great Slave Reef, Nanisivik. and Polaris deposits in the Northwest Territories are examples of limestone replacement ores. The Mel deposit in the Yukon Territory is also an example of a limestone replacement ore body. In the Selwyn Basin, Yukon Territory, numerous massive pyritic lead-zinc-silver deposits occur as near- ly horizontal stratiform, stratabound massive sulfide zones. In the Anvil Range, the sulfide mineralization is in a graphitic schist of Devonian age and is believed to have originally formed syngenetically with its host rocks. The Howard's Pass and Tom deposits are in a pyritic shale environment on the northern fringes of the Selwyn Basin. The Sullivan ore body in southern British Columbia and the Cirque deposit in north- central British Columbia are also shale hosted-type deposits. Volcanogenic massive sulfide type lead-zinc de- posits are formed in a marine environment in the vicinity of volcanic vents. Deposition takes place at the water-sediment interface to form a zoned, poly- metallic sulfide deposit. Some stockwork deposition takes place in the fractured and brecciated volcanic rocks around the vent. The Kidd Creek and Geco deposits in Ontario, and Brunswick No. 12 and Heath Steele deposits in New Brunswick, are prime examples of this type of deposit. INDIA Three deposits containing lead-zinc mineraliza- tion and one containing copper with lead-zinc by4 products were evaluated. Lead-zinc mineralization forms either stratiform, massive complex sulfide de- posits or stratabound, vein-type deposits. The strati- form deposits generally contain high ore grades, whereas the stratabound vein-type are lower in grade. The deposits in the Zawar Group occur in low-grade metamorphosed graywackes, phyllites, dolomites, and quartzites, with associated minor occurrences of un- metamorphosed intrusive igneous rock. The lead-zinc ore bodies are believed to be of hydrothermal origin. Mineralization consists of sphalerite, pyrite, and ga- lena in association with chalcopyrite, pyrrhotite, and arsenopyrite. Silver and cadmium are associated with the ore minerals. The Ambaji copper deposit has relatively high lead and zinc contents. The main ore mineral at Am- baji is chalcopyrite with lesser amounts of the copper minerals chalcocite and covellite, plus galena, sphale- rite, and pyrite. IRELAND Five lead-zinc deposits, three in northeastern Ire- land, one in north-central Ireland, and one in we tern 42 Ireland, were evaluated. Sphalerite, pyrite, and galena are common sulfide minerals. Gangue minerals consist of dolomite, pyrite, barite, quartz, calcite, and marca- site. The stratabound Bula and Tara deposits in north- eastern Ireland occur in Pale Beds of Carboniferous age, composed of silty and oolitic limestones and dolo- mites, enveloping the stratabound sulfide mineralized zone. In the lower section of the ore body, mineraliza- tion forms five separate lenses that converge in the upper ore body to form a single massive sulfide ore body more than 60 m thick. Three major faults dissect the ore body. Folding and faulting of the host rocks have produced a complex ore body shape. The Sabina-Tatestown deposit in northeastern Ireland is stratiform, occurring in (lower carboni- ferous) argillaceous limestones. An east-west fault parallel to the ore body displaces the mineralized zone 70 to 100 m. In north-central Ireland, the Ballinalack deposit is a stratabound ore body within Reef Limestone of lower Carboniferous period. The lead-zinc mineraliza- tion fills fractures and cavities within the Reef Lime- stone to form a few diffuse lenses. Mogul deposit, in western Ireland, has two strati- form ore bodies formed within Waulsortian carbonates and a lower, stratabound ore zone contained within lower dolomites of Tournaisian age. The lower zone is delimited by a northwest-trending fault. JAPAN Nine lead-zinc deposits were evaluated in Japan; one deposit is located on Hokkaido, four in north Japan, and four in central Japan. Two of the deposits are primary copper deposits with lead-zinc byproducts. The stratabound Kuroko or "black ore" type de- posits of Japan are commonly regarded as the classic type of volcanogenic polymetallic (copper-lead-zinc- silver) massive sulfide (and sulfate) deposits, genetic- ally related to explosive felsic volcanism of Miocene age. Mineral assemblages and mineral zoning are simi- lar among typical Kuroko deposits. In the stratiform ore bodies, the upper half is typically rich in galena, sphalerite, and barite (black ore), while pyrite and chalcopyrite are dominant in the lower half (yellow ore). Underlying the stratiform ore bodies are lower grade stockwork ore bodies, characterized by dis- seminated and stockwork-type mineralization of pyrite and chalcopyrite distributed in an irregular funnel shape in felsic lavas and pyroclastics. The stockwork ore is generally strongly silicified and is also called siliceous ore. Along the Japan Sea, from Hokkaido to Kyushu, is a specific geologic province called the Green Tuff Region in which numerous Kuroko deposits occur. In this region, the volcanic rocks show a characteristic greenish color as a result of diagenetic and hydrother- mal alterations. Vein-type base metal as well as silver- gold deposits al-so occur in this region. Mines evaluated in this region include the Ezuri, Fukazawa, Hosokura, Kosaka, and Toyoha deposits. The geology of the Kamioka-Hida mountain re- gion consists of injection gneiss, acid and basic plu- tonic rocks (granite and metabasite), Jurassic sedi- ments, and intrusive Cretaceous stocks and dykes of granite porphyry and quartz porphyry. The character- istic feature of the Hida Complex gneissic rocks is the large number of intercalcerated limestone beds. Lime- stone beds are dragfolded within this complex of meta- morphosed Precambrian to Paleozoic geosynclinal sediments are the host rocks for the numerous ore bodies exploited at the Kamioka Mine. MEXICO The most important producing State for lead and zinc in Mexico is Chihuahua, followed by Zacatecas. Guerrero, San Luis Potosi, and Hidalgo. In the State of Chihuahua, the Santa Barbara ore bodies consist of veins of sulfide mineralization contained in fissures and fractures in shale country rock and andesitic in- trusives. Sulfide minerals are sphalerite, galena, chal- copyrite, and argentite. In the Parral District of Chihuahua, lead-zinc- silver ore bodies occur c.s veins in normal-type faults. The veins are more or less continuous along the strike of the fault. An oxidation zone to 300 m (below sea level) overlies an enrichment zone and a sulfide zone. In northern Coahuila, the La Encantada District has two major ore bodies and several minor ore bodies occurring in a mineralized trend within limestone country rock. Mantos, chimney, vein, and tabular shaped ore bodies are formed along limestone-skarn contacts. The mineralized zones are offset by a series of perpendicular faults. An abundance of iron oxides and complex mineral assemblages characterize the La Encantada deposits. High-grade ore minerals are ce- russite, mimetite, acanthite, argentite, and some native silver. Low ore grade minerals consist of dominant hematite, magnetite, limonite, geothite, and malachite. Other minerals are smithsonite, anglesite, lead jaro- site, marmatite, hemimorphite, azurite, native copper, chrysocolla, and argentojarosite. The Taxco Unit in Guerrero, Mexico, comprises three mines. Ore deposits occur as vein fissures or as replacement ore bodies in limestone beds. Lead-zinc mineralization is higher in the vein fissures than in the replacement ore bodies. Mineralization zones in- clude quartz, argentiferous galena, and sphalerite. Two major ore bodies are located in the Sierra Madre Oriental of southeastern Oueretaro. The ore zones occur in tactite associated with intrusive igneous rocks. Both massive and disseminated mineralization are present. Ore minerals are sphalerite, galena, chal- copyrite, pyrargyrite, proustite, polybasite, and argen- tite. Deposits of the Charcas District in the El Alti- plano region of San Luis Potosi are mineralized frac- ture fillings and replacement bodies associated with intrusive rocks that penetrated limestone formations. Paleozoic and Mesozoic sedimentary rocks were pene- trated by middle Eocene intrusives. Dykes and small fissures near limestone-porphyry contacts and peri- pheral fissures within the Cuesta del Cura Formation contain mineralized replacement bodies. The most im- 43 portant ore bodies are located on the San Bartolo and the San Fidel Faults. Sulfide minerals are sphalerite, argentiferous galena, chalcopyrite, and pyrite. In the San Martin District in Zacateeas. Mexico, a stratabound copper-zinc deposit occurs in the Upper Cretaceous Cuesta del Cura Limestone with minerali- zation in veins and replacement zones. A silver-lead- zinc deposit occurs as disseminations, stringers, and bands in a folded sequence of graywackes. Mineraliza- tion consists of sphalerite, chalcopyrite, bornite. ar- senopyrite. pyrrhotite, pyrite. tremolite. quartz, cal- cite. fluorite. and minor amounts of argentite. native silver, tetrahedite. and scheelite. In one of Mexico's oldest silver destricts. the Fresnillo deposits in Zacateeas occur as veins, stock- works, mantos. and chimneys. The sulfide zone contains quartz, pyrite. arsenopyrite, pyrrhotite. sphalerite, galena, chalcopyrite. pyrargyrite, proustite, polybasite, argentite. and calcite. A number of small lead-zinc deposits and deposits containing lead-zinc as byproducts are located in the Mexican States of Aguascalientes. Durango, Hidalgo, Jalisco. Mexico. Michoacan, Xuevo Leon, Oaxaca. Puebla, Sinaloa, Sonora. and Tamaulipas. MOROCCO The Zeida. Touissit. and Aouli-Mibladen deposits are primarily lead producers: Djebel Aouam and Sidi Lachen are lead deposits with byproduct zinc, and Bou Madine is a zinc-lead-silver deposit. Zeida, the largest lead deposit, lies unconformably on a horizontal plane above Moulouya granite. Overlying the ore zone are argillaceous beds and red mudstones. Host rocks are arkosic sediments consisting of granular quartz and feldspar. Galena and cerussite are major lead minerals and minor quantities of anglesite, pyrite, and chal- copyrite are also present. PERU Lead and zinc mineralization occurs primarily in the Cordillera Occidental region of the central Sierra, dated with three of five major geologic belts in central Peru: Central Andean Mesozoic Belt, Eastern Paleozoic Belt, and Cenozoic Volcanic Belt. Minerali- zation is almost alwavs associated with large longi- tudinal faults and intrusive bodies. Deposits are localized as mineralized faults, breccia pipes, and re- placement mantos in adjacent limestone beds. Terro de Pasco is the largest of the Peruvian lead-zinc mine-, accounting for over 50 pet of the lead and over 35 pet of the zinc resource in Peru. Situated on the line of a major longitudinal fault, it is bounded to the east by the Pucara limestone and to the west by the Paleozoic Excelsior formations. The mineralization 13 in the debris of a volcanic blasthole (15).* Antamina is a low-grade, large-tonnage copper- zinc-silver deposit localized in a tactite zone surround- 1 Italic number- In parenttie*et refer to Items In the list of refer- <1|X. ing a quartz monzonite porphyry intrusion. The host rock is predominantly carbonate with minor shale of Cretaceous age. Approximately 19 pet of the Peruvian zinc resource is contained in this deposit. The remaining deposits evaluated are primarily silver-zinc-lead deposits related to limestone replace- ment mantos or vein fillings associated with limestone, igneous intrusives and volcanic beds. PORTUGAL The Aljustrel and the Neves-Corvo deposit (which was not evaluated for this study"), located in southern Portugal contain lead, zinc, copper, and silver in re- coverable amounts. Both deposits are massive sulfide lenses contained in tuffaceous rocks. Aljustrel. the larger deposit, consists of five ore bodies. Mineraliza- tion is contained within a schistose sericitic rock for- mation. A number of faults including the Messejana Fault displace the mineralized zone. Ore minerals are massive pyrite with fine-grained, disseminated chal- copyrite, sphalerite, and bornite. REPUBLIC OF SOUTH AFRICA The principal lead-zinc deposits in the Republic of South Africa are the Prieska, Broken Hill-Black Mountain, and Gamsberg deposits. The Prieska de- posit is a copper-zinc deposit while the Broken Hill- Black Mountain complex supplies lead and zinc, and Gamsberg is primarily a zinc deposit. The Broken Hill- Black Mountain deposit in Cape Province comprises two massive sulfide ore bodies that were formed on opposite flanks of an Archean complex southeast plunging anticline. Mineralization is believed to be syngenetically related to highly metamorphosed vol- canics. Major sulfides are pyrite, chalcopyrite, sphale- rite, pyrrhotite, and minor amounts of arsenopyrite, galena, magnetite, neodigenite, and molybdenite. Gamsberg is a high-grade zinc deposit similar to the Broken Hill-Black Mountain deposits. SPAIN Of the six deposits evaluated, the Aznalcollar and Sotiel deposits consist of copper mineralization with byproduct lead and zinc; the Cartagena, Reocin, and Rubiales deposits contain zinc ore with byproduct lead; and Linares (El Cobre) contains primarily lead mineralization. Aznalcollar is located in southwest Spain. The local geology is characterized by folding and deformed stress zones of Hercynian orogeny on the east limb of an anticline. The underlying sequence consists of Lower Cambrian carbonates I limestone and dolomites) and fine-grained clastic rocks. The vertical ore body has intricate drag folds and some brecciation has occurred. Mineralized limestone beds within the min- eralized area form ladderlike rungs across the vertical ore body. Minerals are sphalerite, fine-grained galena, and some pyrite and chalcopyrite. 44 Spain's largest lead-zinc deposit is located near Cartegena on the southeastern coast of Spain. The lead-zinc mineralized zone occurs in a Miocene se- quence of pebbly mudstone beds. Mineralization fills cavities and pebble-shaped voids. Ore minerals are marcasite, pyrite, galena, sphalerite, and quartz. SWEDEN The Zinkgruven and Garpenberg Mines, located in central Sweden, extract ore from large complex poly- metallic sulfide ore bodies. Ore mineralization occurs in highly metamorphosed Precambrian country rocks composed mostly of siliceous volcanics. The Vassbo-Guttusjo lead-zinc mineral deposits in west-central Sweden are stratabound, occurring in thin sequences of Lower Cambrian age sandstones. Diabase intrusions dissecting the Precambrian basement con- trol the distribution of the ore bodies. In northwestern Sweden, bordering the eastern slope of the Caledonian Mountains, the Laisvall lead- zinc deposit is stratabound with three major ore zones : a lower ore-bearing sandstone, a middle barren or low-grade sandstone, and an upper ore-bearing sandstone. These flat-lying ore bodies form two thin sheets in the lower and upper layers of the quartzitic sandstone horizons of upper Precambrian-Cambrian rocks. The Stekenjokk copper-lead-zinc deposit in the Skellefte District of central Sweden is a massive py- ritic ore body occurring in Koli metasediments anc 1 metavolcanics. The dominant host rock of ore is ai altered quartz-keratophyre. Predominant sulfide min- erals are galena, sphalerite, chalcopyrite, and pyrite. Other minerals present are barite, fluorite, calcite, and sericite. UNITED STATES A detailed geologic summary of lead and zinc deposits in the United States (7) has been published. This report will focus only on the two most important areas in the United States; southeast Missouri lead deposits and the eastern Tennessee zinc deposits. Missouri The lead deposits in southeastern Missouri occur on the flanks of a dome in a series of Upper Cambrian sedimentary rocks that encircle the St. Francois Mountains. Although there is some mineralized rock in other Paleozoic strata, most of the ore bodies occur in the brown dolomite of the Bonne Terre Formation. Ore deposits are stratiform and the minerals generally occur either in replacement of disseminated deposits, veinlets, or fillings in open spaces. Although the deposits consist mostly of lead-bearing minerals, enough zinc is present for six of the seven producing mines to be included among the top zinc producers in the United States. Small amounts of copper, nickel, cobalt, and cadmium also occur in the deposits but only zinc, copper, and cadmium are currently recovered as byproducts. The Old Lead Belt, on the eastern flank of the St. Francois Mountains, is an area of extensive historical production but is almost mined out, and development is now centered in the more recently discovered Vi- burnum Trend to the west. All of the Missouri sites evaluated in this study are located in the Viburnum Trend except the Higdon and Bonne Terre Mines, which are in the Old Lead Belt. The Indian Creek Mine is not located in the main portion of the Vi- burnum Trend, but is considered to be in an offset portion of it. Tennessee All of the deposits in Tennessee, with the excep- tion of the Copperhill (Ducktown) Mines, are Missis- sippi Valley-type and occur in dolomite or limestone beds in either the Kingsport Formation and/ or the Mascot Dolomite of the Cambro-Ordovician Knox Group. The deposits evaluated for this study occur in either the central Tennessee-Kentucky area, the Copper Ridge District, or the Mascot-Jefferson City District. Strata are generally horizontal in the central Tennes- see-Kentucky region but dip moderately to the south- east in the other two districts. The minerals generally occur in breccia bodies that are very complex and irregular in shape, forming a netlike pattern around islands of barren rock. Indi- vidual breccia bodies located on different stratigraphic levels may be connected by vertical pipe-shaped breccia bodies (breakthrough ore bodies) also containing mineralized rock. All of the deposits are Mississippi Valley-type with sphalerite as the major zinc mineral; minor amounts of galena also occur. The Copperhill Mines are located in the Ducktown Mining District. For this study, the Boyd, Calloway. Cherokee, and Eureka Mines and the North and South Pits were included in the Copperhill evaluation. Minerals occur in metamorphosed massive sulfide accumulations in metamorphosed interbedded gray- wackes and mica schists in the Upper Precambrian Copperhill Formation of the Great Smoky Group. These rocks have been folded and faulted. There are two or possibly three series of beds that are favorable for mineralization, and many of the deposits occur where the favorable sediments have been thickened by folding. All of the deposits contain iron, copper, and zinc, with minor gold, silver, and lead. ZAIRE The Kipushi District of Shaba Province has the only major zinc-copper deposit of the country. The deposit is a replacement body in sedimentary (dolo- mitic) formations of the Kundulungu Series. The mineralized zone is located on the Zaire-Zambia border along a transverse fault crossing the northwest strike of Kipushi anticline. The ore mineralization was formed in two stages. The first stage mineralization consists of pyrite-arsenopyrite-sphalerite and minor galena. 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