finance the $24 million expansion with the aid of a $12 million loan from the InterAmerican Development Bank.

Yugoslavia. During the last quarter of

1971, initial production began at the Péchiney built aluminum smelter at Titograd. The new smelter has an annual capacity of 55,000 tons per year.

Considerable concern has been expressed in recent years by both industry and government representatives over a more effective utilization of secondary materials. In the metal industries secondary materials fall into two categories. New or prompt industrial scrap is scrap metal, dross, or slag that is generated in the production of semifabricated or fabricated aluminum products and includes such items as clippings, lathe turnings, and sheet trimmings. Such scrap may reenter the production cycle several times in a year. Old or obsolete scrap is metal that has been put into use in a variety of forms and returned to the production cycle in the form of wrecked aircraft or automobiles, worn out carburetors, and electrical conductors. Some old aluminum scrap may be in use 30 years before it is discarded, but some items like cans are discarded within a few months after being produced. In the aluminum industry another term, "sweated pig," is used to describe scrap metal (usually old scrap) that has been melted to separate it from the metals with higher melting points and to facilitate handling. Normally, sweated pig has to be further processed before it can be reused. The quantity of metal put into use in finished parts is believed to be at least equivalent to the amount of scrap that is generated in production.

Available data on the recovery and reuse of new scrap include only material that has been purchased, treated on toll, or im

ported, which possibly represents over one-half of the total new scrap generated. New scrap is generated by relatively few firms, and its composition is usually known. Consequently, 80 to 90 percent of all of the new scrap that is generated is recovered and reused in some form. Data on old scrap also includes only material that is purchased, treated on toll, or imported. However, it is believed that such reported data represent most of the old scrap that is recycled.

On this basis it is interesting to note that of the nearly 53 million tons of primary aluminum metal and old scrap that was put into use in crude form in the

United States between 1940 and 1971, only about 3.6 million tons, or less than 7 percent, was old scrap. Assuming that only one-half of the crude metal was put into use in finished products, only 13 percent has been recovered as old scrap. Even on the assumptions that some finished products containing aluminum are exported, some are still in use and a large proportion of the aluminum put into use since 1940 was put there in recent years. It is apparent that recovery and reuse of aluminum from old scrap does not approach the efficiency of the recovery from new scrap.

In recent years the Bureau of Mines has emphasized research to increase the recovery of aluminum and other metals from secondary material. The Bureau operated a 1,000-pound-per-hour pilot plant for recovering old aluminum scrap and other metals and materials from municipal incinerator residues and estimated the investment and operating cost for plants of various sizes. The estimated value of the products produced from the residues was $15.76 per ton of residue treated. The Bureau estimated that satisfactory profits could be made if the value of the product was at least $10 per ton of residue. Capital costs ranged from $1.4 million for a plant capable of treating 250 tons of residue per 8-hour day to $1.7 million for a plant to treat 1,000 tons of residue in a 24-hour day.6

Under the current production and use system, most aluminum products that have worn out, broken, or otherwise become obsolete and are discarded apparently cannot be collected economically from the large number of consumers. Moreover, the aluminum parts in some finished end products are often contaminated with other materials such as plastics, oils, or lacquers, or they cannot be economically separated from adjoining parts made from other ma

terials.

Although independent secondary aluminum smelters traditionally have recovered

6 Henn, J. J., and F. A. Peters. Cost Evaluation of a Metal and Mineral Recovery Process for Treating Municipal Incinerator Residues. BuMines Inf. Circ. 8533, 1971, 41 pp.

most of the aluminum from old scrap that has been recycled, considerable effort by major primary producers and others was underway in 1971 to improve the collection and recycle of used aluminum cans.7 Adequate control of fluoride emissions from alumina reduction cells has been a major problem facing the aluminum industry for many years. Early attempts to recover and reuse the fluorine in cell offgases and the efficiency, investment, and operating costs of several alternative systems, which have been developed through industry research programs, were discussed in a report.8

Emissions from an alumina reduction cell are largely carbon dioxide and some carbon monoxide, but they also contain gaseous hydrogen fluoride and particulates containing fluorine and alumina. According to the report, about one-half of the fluorine from the pots using prebaked anodes is in a gaseous form, and the rest is in a solid form.

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The first control devices were water spray washers installed in roof vents of potlines to remove gaseous fluorides from the outgoing gases. These crude systems were gradually improved to much as 65 percent of the fluorides evolved. Later methods incorporated more efficient gas collection systems, such hooded cells. Following these developments, centrifugal and other mechanical systems and electrostatic precipitators to remove particulate matter more effectively came into use. The gases, essentially free of solids, were then passed through a water spray. With careful operation and good maintenance, this system removed 80 to 87 percent of the fluorides exhausted from the cells.

In most of the systems developed, the solid materials from the cell could easily be recycled into the reduction pots. However, the recovery and reuse of fluorides from wet systems was difficult and prohibitively expensive. To overcome these difficulties Alcoa researchers developed a dry process whereby the cell off-gases are passed through alumina, which absorbs most of the gaseous fluorides and entrains most of the solid particles. The alumina was then used as part of the normal feed to the cell thus recycling most of the fluoride and alumina from the off-gas. This process reportedly removed 99 percent of the fluoride that passed through the sys

tem. In a properly operated, well-hooded cell using prebaked anodes, 95 percent of the gases evolving from the cell reportedly were collected, resulting in an overall fluoride removal and recycle efficiency of up to 94 percent.

The first commercial installation of this dry system was at Alcoa's Badin, N. C., reduction plant in 1967. Since that time the company has installed 123 reactors at eight reduction plants, including three plants on vertical spike, soderberg-type cells. An additional 59 reactors were being designed or were under construction. According to the report, costs of fume control equipment were about one-eighth of the total invested capital in a reduction plant.

Lithium carbonate, which reportedly increases efficiency and reduces fluorine emissions from alumina reduction cells (by 20 to 30 percent for hydrogen fluoride gas emissions), became available in pellet form during the year. The pellets, one-half inch in length and one-half inch in diameter, were priced at 50 cents per pound, delivered, for 500,000-pound minimum annual orders, and reportedly eliminated most losses of lithium from dusting. The aluminum industry continued rather large scale experiments with the long-term use of lithium.

The design and operation of two new alumina reduction plants were described.10 The technology for the reduction plant of Aluminium Bahrain was provided by Montecatini-Edison S.p.A. of Italy. Prebaked anodes are used in the pots, which are about 30 feet in length, 10 feet in width and 5 feet deep. Each of the four pot rooms (two of which were completed) is about 2,100 feet in length, 75 feet wide, and 60 feet high and houses 114 pots arranged in two rows. Power is supplied by

a

1 American Metal Market. Sharp Acceleration Noted on Efforts to Recover All-Aluminum Beverage Cans. V. 78, No. 219, Nov. 16, 1971, p. 12. 8 Andrews, Raynal W., Jr. Fluoride Recovery From Aluminum Reduction Cells. Proc. of symp. on Technology for the Future to Control Industrial and Urban Wastes. Univ. of Mo.Rolla. Continuing Education Series. 1971. pp. 113-115; available for consultation at Univ. of Missouri.

9 Mizoguchi, K., and K. Yuhki. Appraisal of the Operation of Horizontal-Stud Cells With the Addition of Lithium Fluoride. Pres. at 100th Ann. Meeting, Light Metals Comm., Extractive Met. Div. The Met. Soc., AIME Proc., New York, Mar. 1-4, pp. 175-187.

10 Metal Bulletin Monthly. A Second Look at ALBA:1. No. 11, November 1971, pp. 31-36.

Alcan at Lynemouth. No. 11, November 1971, pp. 10-12.

a 250-megawatt power station, which uses natural gas turbines. The facilities include an anode preparation and baking plant. All raw materials are imported, and berthing and unloading facilities were built on an island that was partially constructed from material excavated from the plant site. A water desalination plant also was constructed for plant use. The report indicated that at this plant fluorine and other gases from the pots are merely discharged into the atmosphere where prevailing winds blow them offshore over the Persian Gulf.

The new alumina reduction plant near Lynemouth, England, was designed by Alcan. Individual pots, 30 feet long and 14 feet wide, use prebaked anodes and were completely hooded to facilitate fume collection and recovery. In the first potline, gas cleaning is done by a system designed

by Alcan that utilizes a wet scrubber with an efficiency of greater than 98 percent removal of the gaseous fluoride. The efficiency of this system in removing particulate fluorides was not reported but was said to be dependent on the number of gas scrubbing stages and the pressure drop across them. The wet scrubber effluent was discharged into the sea. Off-gases that escape into the pot room when the hoods were opened for servicing were discharged through covered stacks that were 250 feet high and 22 feet in diameter.

The Lynemouth smelter also was comprised of four pot rooms, each with about 84 pots. The cathode shell was heavily insulated. Busbar connections were organized in order to offset the various magnetic currents that disrupt the stability of metal pad. Power utilization of under 7 kilowatt hours per pound of metal was reported.

The domestic antimony industry in 1971 experienced a reversal of the upward trend in production of primary antimony initiated in 1967; the short supply of the past few years also ended. In the first 9 months of 1971 domestic sales were slow, as the acute scarcity of antimony in late 1969 and early 1970 plus the unusually high price which resulted, cost antimony several of its markets. Imports of antimony declined 27 percent during the year with decreases principally in the form of ores and oxide. Domestic mine production was 9 percent below the 1970 figure; smelter production and industrial consumption were also down. A firmer tone developed in the fourth quarter, which produced increased activity throughout the industry; however, this failed to offset the depressed market that prevailed during the three preceding

quarters.

The price for RMM brand antimony metal, in bulk, f.o.b. Laredo, Tex., dropped 41 percent to 57 cents per pound during the year. The price of ore on the world market also trended downward. The European price range of lump ore, 60 percent antimony, declined from $12.50 to $15.40 per short ton unit in January to

$8.64 to $10 at yearend. In addition to the sluggish domestic economy, price weakness was attributed to more active marketing by the People's Republic of China, one of the world's largest producers.

Legislation and Government Programs. -Effective January 1, 1971, "The General Modification of Tariff Schedules of the United States," Federal Register Document 67-14749, filed on December 18, 1967, reduced the import duty on antimony metal, TSUS No. 632.02, from 1.4 cents to 1.2 cents per pound, and another reduction is scheduled for 1972.

Under Public Law 92-105, enacted August 11, 1971, the General Services Administration (GSA) was authorized to dispose of approximately 6,000 short tons of excess antimony from the national and the supplemental stockpiles. The total inventory of antimony in the national and supplemental stockpiles as of January 1, 1971, was 46,746 short tons. The stockpile objective established April 8, 1970, was 40,700 short tons. No stockpile disposals were made in 1971.

1 Physical scientist, Division of Nonferrous Metals.

MINE PRODUCTION

Domestic production from antimony ores and concentrates and coproduct antimony concentrates from silver mine production declined 9 percent to 1,025 short tons in 1971. In addition 828 tons of byproduct antimony was recovered at primary lead smelters from domestic lead ores. Most of this antimony was not recovered directly but was consumed in the production of antimonial lead.

Sunshine Mining Co.'s new and larger electrolytic plant was the predominant source of antimony, accounting for 83 percent of total mine production. This fully equipped plant is situated on the Sunshine mine property in the Coeur d'Alene mine district, near Kellogg, Idaho. Production capacity was increased to about 2,500 short tons of antimony metal per year. Antimony was recovered from tetrahedrite concentrates mined by Sunshine and from antimony-bearing ores obtained from other companies.

The U.S. Antimony Corp. continued development of its Stibnite mine in Montana. More than 700 feet of drifting and raising was completed during the year to provide access to ore reserves. Work began on a refinery to produce a high-purity metal from the sulfide concentrates. Concentrate shipments on a regular basis began in September. By the end of November production was up to 60 tons of concentrates, or more than 33 tons of contained metal per month. The overall mill recovery was increased from less than 40 percent to more than 75 percent.

The only other source of domestic mine production was a small tonnage of antimony in concentrates produced at a mine in Nevada. This material was consigned to

the Laredo, Tex., smelter of NL Industries, Inc.

SMELTER PRODUCTION

Primary. Primary smelter production of antimony was 11,374 short tons, 15 percent less than that of 1970. Foreign antimony ore and concentrates supplied 83 percent of the primary feed material for smelter production. In addition 9 percent came from domestic mine ore, chiefly as a coproduct of silver ores, and 8 percent as a byproduct of domestic lead ores. Most of the byproduct antimony recovered at primary lead smelters was consumed at the smelter in the manufacturing of antimonial lead; the remainder was processed to oxide or recycled in residues.

Primary smelter output consisted of the following: metal, 34 percent; oxide, 55 percent; antimonial lead, 10 percent; and sulfide and residues, 1 percent. Antimony metal was produced by NL Industries, Inc., at Laredo, Tex., and Sunshine Mining Co., Big Creek, Idaho. McGean Chemical Co., Harshaw Chemical Co., and M & T Chemicals Inc. were the principal producers of antimony oxide. Byproduct antimonial lead was produced by Bunker Hill Co., American Smelting and Refining Co., St. Joe Minerals Corp., and U.S. Smelting Lead Refinery, Inc. McGean Chemical Co. and Hummel Chemical Co. produced antimony sulfide.

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Secondary. Secondary antimony covered from secondary sources decreased from 21,424 tons in 1970 to 20,917 tons in 1971. Of this total, 20,150 tons was recovered by secondary smelters, 59 tons by primary smelters, and manufacturers and foundries recovered the remaining 708 tons. Antimony obtained from old scrap represented 84 percent of the total secondary production and was divided as follows: Batteries, 69 percent; type metal, 15 percent; babbitt, 5 percent; and miscellaneous material, 11 percent. New scrap consisting of residues and drosses resulting from manufacturing and casting, amounted to 3,342 tons, or 16 percent of the total. Processed secondary antimony is usually consumed commercially as antimonial lead. Because the antimony content in secondary sources is normally insufficient to meet the commercial specifications of antimonial