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107,882 tons of scheelite ore averaging 1.22 was stockpiled. The stockpiled material and estimated reserves, which contain approximately 11.7 million pounds of tungsten, are adequate to sustain the current rate of production for about 4 or 5 years. Additional diamond drill exploration of the area, conducted during the summer, indicated the presence of a large low-grade chert formation underlying the present pit. This material, which totals approximately 3.5 million tons containing an estimated 0.65 percent WO3, could only be recovered by more expensive underground operations and is currently not considered ore. It is anticipated that about 700,000 tons of the chert material of a somewhat higher grade can be recovered by open pit operations along with the scarn ore in the present pit.

CTMC carried out mining operations on a 6-day-per-week schedule between June 1 and early October 1971. During this period, 202,000 tons of ore containing an average of 1.06 percent WO3 were mined, crushed, and stockpiled. Waste removal totaled 250,000 tons with an additional 150,000 tons broken and ready for removal in 1972.

The Vancouver leach plant in Vancou ver, British Columbia, operated continuously throughout the year on a 5-day-perweek schedule to upgrade concentrate from Flat River. The metallurgical changes made at the mine concentrator improved the Vancouver leaching operation. Improved recoveries during the latter half of the year resulted in an overall average recovery of 98 percent.

made

to convert

Arrangements were some tungsten concentrate into ferrotungsten in Canada. This procedure will help CTMC to supply the form of tungsten needed for addition to steel melts by high-speed tool steel companies in Canada and abroad.

During 1971 the Canex Tungsten Division of Placer Development Ltd. produced 86,010 stu (1.36 million pounds of contained tungsten) from its Invincible scheelite property at Salmo, near Trail, British Columbia.14 The Canex mill treated 172,512 tons of ore with an average content of 0.61 percent WO3. The recovery averaged 81.6 percent with approximately one quarter of the production recovered as a high-grade table concentrate. During the

year, the average price received for tungsten concentrate was $42.25 per stu of WO3, f.o.b. Vancouver, B.C. The mill inventory at yearend was 22,920 units (0.36 million pounds of contained tungsten).

Some difficulties were encountered in producing a uniform grade of concentrate. By yearend, however, a consistently acceptable grade was being produced and offgrade tungsten concentrates were re-treated and blended to improve marketability. Reserves of broken and unbroken ore at Salmo were 308,000 tons at a grade of 0.67 percent WO3.

Korea, North.-Tungsten ore is found in workable concentrations in quartz-tungsten vein deposits and in scheelite deposits in the Mannen and Kensu mining centers of industrialized North Korea.15 Some 80 percent of the North Korean tungsten concentrate production is believed to be consumed in the country's expanded steel industry. The balance of North Korea's tungsten production is exported primarily to Eastern European Communist bloc countries. Data currently available indicates that a minor amount was also exported to two Western European countries, France and the United Kingdom.

Korea, Republic of.-The Sandong deposit is one of the most significant single occurrences in the world, containing 1 to 3 percent WO3 and 1 to 1.5 percent molybdenum plus bismuth. Production from the Sandong mine is responsible for almost 90 percent of the South Korean tungsten output as shown in the following tabulation: 16 Company

Bando Mining Co., Ltd..
Chong Yang Industries Co., Ltd.
Korea Tungsten Mining Co., Ltd.:
Dalsong mine.

Sandong mine.

Okbang Mining Co., Ltd.

Wolak Mining Co., Ltd. Other companies (11 mines)

Total.

Short tons

80

42

86

3,640

100

42

99

4,089

Because tungsten exports reportedly represent over a third of South Korea's earnings from mineral exports, a modernization and expansion program was completed in 1971

14 Placer Development Ltd. (Vancouver, Canada). Annual Report 1971. 28 pp.

15 World Minerals and Metals. The Minerals Industry of Korea. The British Sulphur Corp. Ltd. (London), No. 6, March-April 1972, pp. 20-22.

16 Bureau of Mines. Tungsten: Republic of Korea. Mineral Trade Notes, v. 69, No. 6, June 1972, p. 26.

at the mill adjacent to the Sandong mine, raising capacity from 1,550 to 1,800 tons per day.

Portugal.-Beralt

Tin and Wolfram Ltd., the country's major tungsten producer, recovered tungsten from its orebody located at Panasqueira, Biera Baixa, Portugal, and subsequently treated the ore to produce

high-purity commercial-grade tungsten concentrate.17 Owing to the sharp decline in the stoping grade of ore, the production of tungsten concentrates fell 11 percent to 1,569 tons of tungsten. Production of byproduct tin concentrate fell 24 percent to 29 tons, and production of byproduct copper concentrate fell 34 percent to 506 tons in 1971. The areas available for mining during the year were lower in grade as a result of the depletion of many of the richer areas during previous years. Development is being concentrated in new areas to the South, where richer values are thought to exist; nevertheless, it can be expected that mining operations will continue in the future at a lower average grade.

Because of the recent drop in tungsten prices, the reserves at Panasqueira that could be profitably mined were drastically reduced. To economically mine a larger portion of these ores, which are marginal at present price levels, the mining costs must be lowered. Reduced unit costs can be achieved by increased production, however, this will require a larger proven ore reserve. Increased reserves will also provide greater flexibility in grade control, particularly during severe tungsten price fluctuations. To improve the firm's reserve position development work was increased by 50 percent during the year and will be increased further during the next few years. Exploratory work will continue to probe ahead to determine the trends in grade beyond the area currently being mined.

The proposed increase in production and development will depend largely on the availability of an adequate supply of skilled labor. The labor shortage coupled with high absenteeism continued to be a serious problem. While Beralt's labor force was up to strength at yearend, turnover remained high and there was a shortage of skilled and technically experienced ma

chine operators. The problem was partially alleviated by the employment of untrained or semiskilled labor from Cape Verde.

The new heavy media separation preconcentration plant became operational in July. Considerable difficulties were experienced owing primarily to the inability of the main bucket elevator to achieve its rated capacity. The plant continued operations at a reduced rate during the year and operated in conjunction with the handpicking plant until modifications could be made. The Rio mill operated efficiently throughout the year and the high grade of concentrate was maintained at an average assay of 75.5 percent WO3.

A comprehensive feasibility study conducted on the erection of a tungsten proc essing plant in Portugal indicated that a plant of economic size would be costly and, at best, only moderately profitable. However, bearing in mind the Portuguese Government's desire to have tungsten concentrates processed within the country and the advantage to Beralt in securing a long term domestic outlet, discussions were conducted to plan for the establishment of such a plant when economic conditions improve.

While some 11 Portuguese mines report tungsten production, Beralt is the country's major tungsten producer.18 Of the 10 small tungsten mines, one, Minas de Boralha, is under French ownership.19

Rhodesia, Southern.-Although tungsten was produced by some 60 small and intermittent operations located primarily in the Bulawayo and Salisbury districts, the major production was obtained from the Beardmore mine of Messina (Transvaal) Development Co. at Bikita. The R.A.N. mine at Bindura, which had previously been Rhodesia's major tungsten producer, is no At longer active. Messina's Beardmore mine in 1971, 36,190 tons of ore averaging 0.88 percent WO3, was recovered from mine stopes and 2,860 tons containing an average of 0.40 percent were obtained from the mine's development ends.20 An addi

17 Beralt Tin and Wolfram Ltd. (London). Annual Report 1971. 18 pp.

18 UNCTAD Committee on Tungsten (Geneva, Swizerland). Tungsten Statistics. V. 6, No. 2, April 1972, 68 pp.

19 World Minerals. Minerals World. The British Sulphur Corp. Ltd. (London), No. 1, May-June 1971, pp. 18-26.

20 The Messina (Transvaal) Development Co. Ltd. (Johannesburg, Rep. of South Africa). Annual Report 1971. 31 pp.

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terial was stored separately for future treatment. A special processing plant which was designed for this material will become operational by mid-1972. Messina announced plans to mill 39,600 tons of ore during 1972 for a production of 220 tons of WO3 in concentrate. At yearend 1971, Beardmore's ore reserves totaled 74,800 tons containing 0.71 percent WO3.

Zaire, Republic of.-Production of tungsten concentrate in the Republic of Zaire (formerly Congo-Kinshasa) was reported to have increased about 37 percent to 471 tons during 1971.21 Almost all of the 1971 tungsten production was recovered from three major deposits in Kivu Province where transportation from mine to port presented a major problem.

TECHNOLOGY

Studies conducted by Bureau of Mines scientists evaluated methods of electrowinning tungsten from scheelite 2(CaWO4) concentrates.22 Crude WO3 prepared by the acid digestion process was processed by electrometallurgical methods to produce tungsten metal of 99.9 percent purity. The tungsten recovery varied from 79 to 83 percent and most of the tungsten loss was in the dragout electrolyte which could be recovered by subsequent hydrometallurgical processing.

The applicability of the freeze-drying technique for the preparation of dispersion-strengthened tungsten powders was investigated by Bureau of Mines engineers.23 They reported that although the high surface area of tungsten powder prepared by freeze drying is advantageous in some applications, the powder may be more readily contaminated by oxygen. Tungsten powder made by the freeze-drying technique can be fabricated by powder-metallurgical (PM) techniques into tungsten sheet with a lower recrystallization temperature, a lower ductile-to-brittle transition temperature, and a higher purity than commercial PM tungsten sheet.

A method of strengthening the hightemperature properties of tungsten alloys was developed by Bureau metallurgists.24 This process, designated oxyreaction, involved additions of a reactive metal compound powder, zirconium nitride (ZrN), zirconium tungsten (ZrW2), or hafnium tungsten (HfW2), to the tungsten base

metal which contains some oxygen. The oxyreaction process circumvents many of the agglomerating and coarsening problems encountered in conventional methods for dispersing a stable oxide in the metal. Oxyreaction strengthening results from a combination of solid-solution strengthening and dispersion strengthening.

The second report in a series, which describes current practices and trends in the application of solvent extraction processes that lead to the recovery of byproduct tungsten, was issued by the Bureau of Mines during the year.25 The first report of this series described the fundamentals of solvent extraction.26

Studies were conducted during the year by Bureau metallurgists in an attempt to develop economic techniques to recover

21 U.S. Consulate, Lubumbashi, Rep. of Zaire. Minerals Industry Report for Zaire. State Department Airgram A-021, June 6, 1972, 17 pp.

Gomes, John M., Kenji Uchida, and M. M. Wong. Comparison of Techniques for Electrowinning Tungsten From Scheelite. BuMines Rept. of Inv. 7580, 1971, 10 pp.

23 Ferrente, M. J., R. R. Lowery, and G. B. Robidart. Tungsten and Dispersion-Strengthened Tungsten Made By Freeze Drying. BuMines Rept. of Inv. 7485, March 1971, 32 pp.

24 Blickensderfer, Robert, Mark I. Copeland, and William L. O'Brien. A new Internal Oxidation Process for Strengthening Tungsten. BuMines Rept. of Inv. 7521, June 1971, 40 pp.

25 Rosenbaum, Joe B., D. R. George, and Joan T. May. Metallurgical Application of Solvent Extraction, Part 2: Practice and Trends. BuMines Inf. Circ. 8502, January 1971, 19 pp.

26 Bridges, D. W., and J. B. Rosenbaum. Metallurgical Applications of Solvent Extraction, Part I: Fundamentals of the Process. BuMines Inf. Circ. 8139, 1962, 45 pp.

tungsten from the large low-grade brine deposits of Searles Lake, Calif.

The chlorination kinetics of tungsten, molybdenum, and their binary alloys were studied as part of the Bureau's evaluation of chlorine extractive metallurgy processes.27 Of the metals and alloys studied, tungsten was the least reactive and its single crystals showed marked anisotropy upon chlorination.

Another Bureau of Mines study evaluated methods of reclaiming tungsten carbides from secondary materials (scrap) .28

A study of domestic ferroalloy usage, which reviewed tungsten resources, U.S. Government stockpile activities, ferroalloy specifications, and pollution control activities, was released during the year.29 An improved definition of the superalloy class of materials was developed, the demand for tungsten in the steel industry was evaluated, and tungsten demand in ferroalloys was projected to 1980.

The elevated temperature properties of chemical vapor deposited (CVD) tungsten tubing and the determination of friction coefficients of tungsten was evaluated directly from hoop stress tests.30 Several studies reported by the National Aeronau tics and Space Administration (NASA) evaluated the development of CVD tungsten by the reduction of gaseous tungsten hexafluoride (WF6) with hydrogen (H2) gas.31 CVD tungsten metal of essentially 100 percent purity and density is built up as a dense deposit on a heated graphite mandrel. Following deposition, the mandrel is separated by simple machining, leaving a tungsten shell structure of the required shape and thickness.

Pressure hydrometallurgy has been successfully used in the U.S.S.R. to extract tungsten and molybdenum by single-stage leaching of low-grade materials inside a rotating autoclave.32 The concentrate originally contains about 8 to 12 percent tungsten, which is placed into solution by leaching in an autoclave. The resulting solution is separated and filtrated. The first filtrate is recycled for pressure-leaching of high-grade scheelite concentrates.

A comprehensive quarterly report, Tung

sten News, reports the latest available technical information on tungsten. Interested persons can be placed on the mailing list to receive this report by sending a request to: Dr. Janet Z. Briggs, Vice President and Director of Technical Information, Editor -Tungsten News, Climax Molybdenum Co., 1270 Avenue of the Americas, New York, N.Y. 10020.

Methods of producing high-purity ammonium metatungstate and of separating molybdenum from tungsten values during the liquid-liquid solvent extraction of ammonium metatungstate from aqueous ammonium tungstate were developed.33

27 Landsberg, C. L. Hoatson, and F. E. Block. The Chlorination Kinetics of Tungsten, Molvbdenum, and Their Alloys. J. Electrochem. Soc., v. 118, No. 8, August 1971, pp. 1331-1336.

28 Starliper, A. G. and H. Kenworthy (assigned to the U.S. Department of the Interior). Reclamation of Refractory Carbides From Carbide Materials. U.S. Pat. 3,595,484, July 27, 1971.

29 National Research Council. Trends in the Use of Ferroalloys by the Steel Industry of the United States. National Materials Advisory Board, NMAB-276, (Nat. Acad. Sci.-Nat. Acad. Eng.), Washington, D. C., July 1971, 130 pp.

30 Chun, J. S., P. S. Nicholson, A. Sosin, and J. B. Byrne. Chemical Vapor Deposited Tungsten -Mechanical Evaluation at High Temperature. J. Electrochem. Soc., v. 118, No. 9, September 1971, pp. 1492-1498.

31 National Aeronautics and Space Administration. Fabrication of Large Tungsten Structures by Chemical Vapor Deposition. NASA Tech. Brief 71-10212, July 1971, 2 pp.

Stubbs, V. R. Investigation of Advanced Regenerative Thrust Chamber Designs. NASA-CR72742, Nov. 15, 1970, 88 pp. (Available from the National Technical Information Service, Springfield, Va. as N71-14135.)

National Aeronautics and Space Administration. Welding, Bonding, and Sealing of Refractory Metals by Vapor Deposition. NASA Tech. Brief 67-10232, July 1971, 2 pp.

33 Habashi, Fathi. Pressure Hydrometallury: Key to Better and Nonpolluting Processes. Eng. and Min. J., v. 172, No. 2, February 1971, pp. 96-100.

Pressure Hydrometallurgy: Key to Better and Nonpolluting Processes. Eng. and Min. J., v. 172, No. 5, May 1971, pp. 88-94.

33 Chiola, Vincent, Phyllis R. Dobbs, Fred W. Liedtke, and Clarence D. Vanderpool (assigned to Sylvania Electric Products, Inc., New York). Process for Producing Ammonium Metatungstate. U.S. Pat. 3,591,331, July 6, 1971.

Chiola, Vincent, Phyllis R. Dobbs, and Tai K. Kim (assigned to Sylvania Electric Products Inc., New York). Separation of Molybdenum Values From Tungsten Values by Solvent Extraction. U.S. Pat. 3,607,007, Sept. 21, 1971.

Chiola, Vincent, Phyllis R. Dobbs, Tai K Kim, and John A. Powers (assigned to Sylvania Electric Products Inc., New York). Separation of Molybdenum Values From Tungsten Values by Solvent Extraction. U.S. Pat. 3,607,008, Sept. 21, 1971.

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The domestic and world uranium surplus continued during 1971. Domestic U308 mine and mill production was at a rate similar to that of 1970. Ore reserves continued to increase although exploration for uranium was declining. Fewer mines were in operation. One new mill went on stream, and three other mills were scheduled for completion in 1972. A problem facing the industry was to provide incentives for increased exploration for new reserves that will be needed in the future.

The year 1971 was the first full year that the U3Og market was entirely private. The Atomic Energy Commission (AEC) terminated its U3Os purchasing program at yearend 1970 after acquiring U3Og valued at nearly $3 billion since the program's inception in 1948, including a large stockpile. The AEC proposed a schedule for disposal of this stockpile over a period of several years, but industry response was negative.

The domestic U3O8 price remained soft under conditions of excess supply. The estimated average domestic price per pound was in the $6 to $6.50 range. Prices in the world market apparently were lower. New mines were under development in Australia, Canada, and the Territory of SouthWest Africa.

Progress was made in new uranium enrichment technology and world enrichment capacity. Expansion was underway at the AEC's three gaseous diffusion plants, which, however, continued to operate at only partial capacity. The major industrialized nations continued research on enrichment methods and were negotiating agreements for future production and marketing of enriched uranium. The AEC offered to share its gaseous diffusion technology with U.S. industry 2 and with foreign governments under appropriate safeguards. In addition to uranium enrichment, private facilities were under development for nu

clear fuels manufacturing, reprocessing, and waste management.

New nuclear reactors for electric power were completed in the United States, the leader in commercial nuclear power development, and worldwide. Several of the less developed countries announced plans for nuclear power, and most of the industrialized nations were committed to ambitious nuclear programs for future energy supplies.

The domestic nuclear power program faced new problems resulting from the landmark decision of a Federal Court of Appeals in the case involving the nuclear plant at Calvert Cliffs, Md. This decision, not appealed, committed the AEC to an evaluation of the total environmental impact of a nuclear facility in implementing the National Environmental Policy Act of 1969. A total of 103 plants in operation, under construction, or on order at that time were affected by the decision. The AEC commenced a major reorganization of its regulatory function in order to consider total environmental quality, with public participation, and to increase efficiency in the licensing and regulatory responsibility. New AEC regulatory legislation, guidelines, and interim criteria, which affected the status of nuclear plants at all stages of development, were announced.3

New emphasis was placed on fast breeder development following the President's announcement committing the Nation to a commercial fast breeder reactor during the 1980's. Plans were made for two demonstration liquid-metal fast-breeder reactors

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