II-Kano and North-Central States; Area III-Benae-Plateau State; Area IV-NorthEastern States; Area V-Western and Lagos States; Area VI-East-Central, Rivers and South-Eastern States; Area VII-Mid-West States. Of these seven zones, Area III accounts for more than 90 percent of Nigeria's production of columbite.

Zaire (formerly Congo Kinshasa).-Congo-Etain, a Congolese company owned 50 percent by the Congolese Government and 50 percent by the Belgian company Compagnie Géologique et Minière des Ingénieurs et Industriels Belges (GÉOMINES), produced approximately 178,000 pounds of concentrate in 1970,

columbite-tantalite

which was equal to a little more than half

Table 13.-Columbium and Tantalum:

of Zaire's 1970 columbite-tantalite production.

Somikubi-Union Carbide (SOMUCAR), owned 53 percent by Union Carbide Corp., holds a 741,300-acre concession on which it plans to begin pyrochlore production. Production was originally to have started in 1970, but was delayed in 1970 and 1971 owing to technical difficulties.

The Congolese company KIVUMINES, owned by the Belgian company SOBAKI (75 percent) and the American group Engelhard Minerals and Chemicals Corp. Philipp Brothers (25 percent), continued to produce mixed cassiterite/columbite-tantalite ore from deposits at Kabili, 262 kilometers from Bukavu.

'Exports.

Kawecki Berylco Industries developed a four-step process for upgrading low-grade tin slags to a 40- to 50-percent combined tantalum plus columbium oxides concentrate.13 The tin slags were smelted with coke to produce a carbidic hearth concentrate of 20 to 25 percent (Ta,Cb) 205; the concentrate was then ex

othermically fused with sodium nitrate and finely divided carbon to form a fusion

13 American Metal Market. Tin Slag Called Good Source For Tantalum, Columbium. V. 78, No. 44, Mar. 5, 1971, pp. 1 and 10.

Gustison, R. A., J. A. Generazzo. Exothermic Fusion of Eastern Tin Slag Carbides to a Tantalum-Columbium Concentrate. J. Metals, v. 23. No. 8, August 1971, pp. 45-48.

mass which was then water-leached and acid-leached to remove silica, titanium, alumina, tungsten, iron and caustic.

A new cladding process was developed by Fansteel Inc., North Chicago, Ill., for lining process equipment with a thin film of tantalum about 10 mils thick which could make tantalum competitive with glass as a lining for processing equipment.14 The Eco Pump Corp., South Plainfield, N.J., signed an agreement with Fansteel Inc., to use the Fanclad process to produce small, corrosion-resistant, heavyduty pumps, and Fansteel Inc. was in the process of installing new facilities at its Torrance, Calif., plant for coating large pieces of equipment.

A new alloy steel was developed by St. Lawrence Columbium and Metals Corporation of Montreal, Canada. The alloy was described as a deep-drawing, conventional low-carbon steel with columbium added at a level of 0.06 to 0.25 weight-percent. The new columbium-bearing steel was reported to have better drawability and lower fabricating costs.15

Researchers at Hiroshima Technical Institute developed a weldable tantalum-clad steel featuring titanium as an intermediate metal.16

A group of organometallic tantalum and columbium materials were discovered and described as being the most efficient superconductors yet developed.17 If further research confirms their practical application, this new group of organometallic superconductors could prove useful for magnets, electrical devices, and high-energy physics apparatus, and possibly for advanced electric power transmission systems.

The Martin-Marietta Corp. evaluated TP Nickel-Chromium and coated T-222 Tantalum as primary materials for structural elements in hypersonic aerospace vehicles.18 In a coating investigation for protecting T-222 tantalum above 3000° F, the Sylvania coating (R512C) was found to give better oxidation protection from quartz-lamp radiant heating in air than the other materials tested. T-222 Tantalum bolted joints, TD Nickel-Chromium riveted joints, and honeycomb panels of both materials were used as structural test specimens. Stress distribution was con

ducted up to 2100° F for TD Nickel-Chromium and 3200° F for T-222 Tantalum. Ultimate strength trends were defined for tension, compression, shear, and biaxial tension in the honeycomb panel specimens.

A feasibility study of clad-core columbium alloy combinations for turbine blades was completed by TRW, Inc.19 Test results indicated that the cladding concept of using an oxidation-resistant coated cladding alloy to prevent catastrophic oxidation of a high-strength but more oxidized core alloy was feasible.

A research program was concluded at Nuclear Metals Division of the Whittaker Corp. which demonstrated that high-quality tantalum-stainless steel sleeves and tandem joints could be produced by coextrusion techniques.20

The continuing interest in methods of extraction and beneficiation of columbium and tantalum ores was reflected by some of the patents issued during the year.21

14 Chemical and Engineering News. Process Lowers Cost of Tantalum Linings. V. 49, No. 49, Nov. 29, 1971, p. 18.

15 Mining and Minerals Engineering. Potential for Columbium. V. 7, July 1971, p. 32.

16 Iron Age. Solve Problems of Welding Tantalum-Clad Steel. V. 208, No. 24, Dec. 9, 1971, p. 27.

17 Gamble, F. R., J. H. Osiecki, M. Cais, and R. Pisharody. Intercalation Complexes of Lewis Bases and Lavered Sulfides: A Large Class of New Superconductors. Science, v. 174, No. 4008, Oct. 29, 1971, pp. 493-497.

18 Norton, A. M. Hypersonic Aerospace-Vehicle Structures Program. Martin Marietta Corp. (Denver, Colo.), AFFDL-Tech. Rept. 68-129, v. 5, March 1970, 324 pp. Available from Defense Documentation Center, Alexandria, Va. to registered users. AD 866190.

19 Scheirer, S. T.. Development of Columbium Alloy Combinations for Gas Turbine Blade Applications. TRW, Incorp. (Cleveland, Ohio), AFMLTech. Rept. 70-187, October 1970, 167 pp.; Available from Defense Documentation Center, Alexandria, Va. to registered users. AD 876475.

20 Friedman, G. I., "Coextruded Tantalum-316 Stainless Bimetallic Joints and Tubing." Nuclear Metals Division, Whittaker Corp. (Concord, Mass.), NASA CR-72761, October 1970, 61 pp.; Available from National Technical Information Service, Springfield, Va. N71-12419.

21 Cenerazzo, C. E., E. E. Mosheim, and C. E. Marvasi (assigned to Kawecki Berylco Industries, Inc.). Upgrading the Tantalum and Columbium Content of Tin Slags. U.S. Pat. 3,585,024, June 15, 1917.

Erhard, A. E. and J. B. Allison (assigned to Molybdenum Corp. of America). Process for Recovery of Columbium. U.S. Pat. 3,640,679, Feb. 8, 1972.

Robert, D. (assigned to Ste. de Produits Chimiques d'Auby). Method of Selectively Separating Solid Particles by Electrostatic Sorting in FluidBed. U.S. Pat. 3,563,375, Feb. 16, 1971.

World mine production of copper achieved a record high for the fourth consecutive year. Copper developments in progress or in advanced planning stages were in evidence in many countries.

The domestic copper industry experienced curtailed mine, smelter, and refinery outputs as a result of labor strikes lasting variously from 4 to 12 weeks at most operations during July, August, and September of 1971. Consumption of refined copper declined 1 percent from that of 1970. Imports of refined increased while imports of blister and exports of refined were reduced. Price quotations changed three

times with a net decrease of 22 cents to a yearend quote of 50 to 50/2 cents per pound.

Legislation and Government Programs.The total copper in the national stockpile on December 31, 1971, was 60,112 tons of oxygen-free, high-conductivity (OFHC) copper, 7,067 tons of copper in berylliumcopper master alloy, and 191,509 tons of copper in "other" classifications, for a total of 258,688 tons, 33 percent of the objective of 775,000 tons.

1 Physical scientist, Division of Metals.

Nonferrous

Production:

Mine.

Smelter.

130,000

75,000

303,000

378,000

1,623,000

2,097,000 42.2

2,258,000 47.9

2,089,000 58.2

2,068,000 52.0

_short tons. ...do.

Price: London, average cents per pound...

? Revised.

The Office of Minerals Exploration (OME) continued to offer up to 50-percent Government participation in the authorized cost of exploration for copper deposits. There were no contracts executed in 1971 that involved copper.

Set-asides for refined copper and “ammo strip," under the program of copper controlled materials for defense purposes, were eliminated, effective January 1, 1971. How

PRIMARY COPPER

ever, set-asides for certain brass mill, wire mill, and foundry products were retained.

The excise tax on imported copper was reduced to 1.0 cent per pound, effective January 1, 1971. This reduction was in accord with the Kennedy Round Trade Expansion Act of 1962 designed to progressively reduce the rate to 0.8 cent by 1972. Duties have been suspended by public laws from 1966 to June 30, 1972.

Mine Production.-Domestic mine production was 1.52 million tons, a decrease of 11 percent and the smallest quantity since 1968. In addition to production lost during labor strikes, several mines curtailed operations during the latter part of the year owing to insufficient smelter capacity to process accumulated stocks of copper concentrates. Principal copper-producing States were Arizona with 54 percent of the total, Utah (17 percent), New Mexico (10 percent), Nevada (6 percent), Montana (6 percent), and Michigan (4 percent). These six States accounted for 97 percent of the total production.

Open-pit mines accounted for 82 percent of mine output and underground mines for 18 percent. The production of copper from dump and in-place leaching, largely recovered by precipitation with iron, was 154,500 tons, or 10 percent of mine output. Total copper recovered by leaching methods was 235,300 tons, of which 199,300 tons was precipitated with iron and 36,000 tons was electrowon.

Duval Corp., a subsidiary of Penzoil United Corp., operated the Duval Sierrita mine near Tucson, Ariz., for the first full year at an average daily rate of 70,300 tons of ore. The company temporarily suspended operations in late December at the adjacent Esperanza copper-molybdenum property owing to a shortage of smelting capacity to treat the stockpiled concentrates. Duval also operated a copper-gold-silver property at Battle Mountain, Nev.

Strikes at the Butte, Mont., and Twin Buttes, Ariz., mines plus a major pit slide at the Arizona property of The Anaconda Company resulted in reduced outputs of 88,700 and 50,700 tons of copper, respectively. Production at the Yerington, Nev.,

mine was approximately unchanged at 42,500 tons. Productive capacity continued to be expanded at the Montana mines with reactivation of the underground Leonard mine in the fourth quarter, a program to double production of precipitates to 42,000 tons in 1972 from leaching low-grade dump material, and improvement in the recovery of copper at the concentrator. The Anaconda Company concentrator was shutdown in the fourth quarter and all ore is now processed at the Butte concentrator.

Kennecott Copper Corp. operated mines in Arizona, Nevada, New Mexico, and Utah; these mines produced a combined total of 456,100 tons of copper, compared with the record high of 518,900 tons produced in 1970. The Utah Copper Division accounted for 261,800 tons of the total. New tailingsretreatment plants were installed in May at the Utah operations, providing an increase of approximately 15 tons of copper production per day. At the Nevada Mines Division, mining was suspended at the Tripp-Veteran pit in October, with operations transferred to the Ruth pit.

The American Smelting and Refining Co. (Asarco) operated three copper mines in the vicinity of Tucson, Ariz. The Mission unit, closed by strike during July and August, produced 40,600 tons of copper in concentrates, compared with 47,700 tons produced in 1970. The Silver Bell unit was unaffected by the strike and increased output 3 percent to 23,100 tons of copper in concentrates and precipitates. Production at the San Xavier mine was limited to copper-bearing siliceous flux ore for use at Asarco's Hayden smelter. Consideration of a fourth domestic copper mining project was advanced during the year with engineering studies for development of the Sacaton deposit near Casa Grande, Ariz.