Thorium By Walter C. Woodmansee 1 A continuing limited demand and excessive stocks for thorium prevailed during 1971. Growing demand for certain rareearth elements in monazite, the principal domestic source of thorium but mined essentially for its rare-earth content, contributed to the oversupply of thorium. A few companies discontinued thorium processing operations because of the weak market. However, there were indications that demand for thorium hardener, used in magnesium alloys for aerospace applications, may increase moderately in the near fu ture. The long-term potential for thorium nuclear fuels remained good. Progress was made in commercial markets for these thorium-based nuclear fuels. Legislation and Government Programs. -Effective January 1, 1971, under the "Kennedy round" schedule of tariff reductions, ad valorem duties were reduced to 21 percent on thorium compounds, 7 percent on the metal, and 9 percent on thorium alloys. Further reductions to 17.5 percent, 6 percent, and 7.5 percent, respectively, were scheduled for January 1, 1972. A 10-percent ad valorem surcharge was effective August 16 to December 20, 1971. The Congress authorized General Services Administration (GSA) disposal of an additional 210 tons ThO2 equivalent in thorium nitrate that is in excess of the stockpile objective of 40 tons Tho2 equivalent. The entire excess of 1,792 tons ThO2 equivalent beyond stockpile needs has now been authorized for disposal, but no sales were made during the year. DOMESTIC PRODUCTION Mine Production.-Monazite production of Humphreys Mining Co. near Folkston, Ga., was substantially reduced in 1971, although content of rare-earth oxide (REO) increased from 55 percent to 59 percent. Average ThO2 grade was 5 percent. Heavymineral sands were mined by suction dredge for their titanium minerals and zircon content. The byproduct monazite was sold under contract with W. R. Grace & Co., Chattanooga, Tenn. Monazite was processed essentially for its REO content. Thorium-bearing residues were stockpiled for processing as needed. Humphreys Mining Co. continued land rehabilitation of a 6-square-mile area disturbed by mining. Mill waste was used as fill, and, after grading, topsoil was respread, fertilized, and planted with grass. These methods were employed for several years before the Georgia Surface Mined Land Use Law went into effect in 1968. At yearend, development work by Titanium Enterprises, a join venture of American Cyanamid Co. and Union Camp Corp., was near completion on a Pleistocene beach deposit, 35 miles inland and 10 miles from Green Cove Springs, Fla. Mine products will be ilmenite, leucoxene, rutile, monazite, and zircon.3 Kerr-McGee Chemical Corp. conducted market feasibility studies on titanium, rare-earth elements, and thorium from a mineral sand deposit in western Tennessee, where a pilot-plant operation had been underway. In September, mining was terminated at Kendrick Bay, Alaska, after about 56,000 tons of high-grade uranium-thorium ores 1 Geologist, Division of Nonferrous Metals. U.S. Congress. An Act to Authorize the Disposal of Thorium from the Supplemental Stockpile. Public Law 92-96, Aug. 11, 1971, 85 Stat. 323. 3 Engineering and Mining Journal. V. 173, No. 1, January 1972, p. 134. were shipped to the uranium mill at Ford, Wash. The mining operation was a joint venture of Newmont Mining Co. and Midnite Mines Inc. The principal ore minerals were uranothorite and uranothorianite in granitic rocks.4 Thorium, which occurred in equal quantities with uranium, was not recovered because of lack of a market. Refinery Production. The principal do mestic firms processing monazite for rareearth elements and thorium were W. R. Grace & Co., at Chattanooga, Tenn., and Lindsay Rare Earths, affiliated with KerrMcGee Chemical Corp., West Chicago, Ill. A number of thorium-processing companies maintain stocks of various compounds and the metal for nonenergy use and for nuclear fuels. Table 1.-Companies processing and fabricating thorium, 1971 On the basis of estimated production and imports of monazite and thorium compounds, apparent consumption was about 300 tons ThO2 equivalent in 1971. However, actual industrial demand was probably substantially lower; the available monazite supply was processed essentially for its rare-earth content, and most of the thorium residues entered company holding areas. Nonenergy industrial demand was estimated at 100 to 150 tons ThO2 equivalent for use (in order of relative importance) in Welsbach incandescent gas lamp mantles; hardener (30 to 40 percent thorium content) for magnesium-thorium alloys (3 percent thorium content) in aerospace applications; dispersion hardening (2 percent ThO2 content) of metals such as nickel, tungsten, and stainless steel; and miscellaneous electronic, refractory, and chemical (catalytic) applications. In the nuclear field, research and devel opment studies, sponsored by both the Atomic Energy Commission (AEC) and industry, continued on thorium-uranium fuels, reactor concepts using these fuels, and thorium fuels reprocessing. Examples of the application of the Th232-U233 fuel cycle are the high-temperature, gas-cooled reactor (HTGR), the molten-salt breeder reactor, and seed-blanket loadings for the pressurized water reactor at the Atomic Power Station, Shippingport, Pa.5 * Stephens, F. H. The Kendrick Bay Project. Western Miner. V. 44, No. 10, October 1971, pp. 151-158. U.S. Atomic Energy Commission, Division of Industrial Participation. The Nuclear Industry1971. WASH-1174-71, December 1971, p. 52. AEC's Bettis Atomic Power Laboratory was developing a Th232-U233 fuel reactor core to demonstrate breeding in the light water reactor (LWR) system. This is an advancement of seed-blanket technology and is the only known concept for improving fuel efficiency in the common, thermal LWR. According to AEC, successful LWR breeding could lead to development of large domestic thorium resources. Late in the year, Philadelphia Electric Co. ordered two 1,150-megawatt HTGR's from Gulf General Atomic Co. (GGA), San Diego, Calif. This was the first fully commercial order for the HTGR.6 Research and development were underway on connecting the high-temperature reactor to gas turbines, which would eliminate the steam cycle. A problem is the reprocessing of the Th232-U233 fuel, which may prove costly. GGA has designed 770-megawatt and 1,000-megawatt HTGR's. The latter will have an initial fuel core using 40 tons of ThO2 and refueling (after the second year) of 10 tons ThO2 per year. The Th232-U233 fuel consists of multilayered, ceramic-coated particles, which have high integrity at elevated temperatures, high burnup, ease of fabrication, and good quality control. PRICES The monazite price continued to decline in the international market. According to trade statistics of the Bureau of the Census, the average declared value for imported monazite was $113.77 per ton, compared with $123.96 in 1970. Domestic monazite was quoted at $180 to $200 per ton (based on REO only), little changed from 1970, but the market price was lower and was further depressed toward the end of the year. Prevailing prices for thorium nitrate, oxide, and metal showed little, if any, change during the year. Prices listed by the Davison Chemical Division, W. R. Grace & Co., Chattanooga, Tenn., were in the following ranges, per pound, depending on quantity of purchase: Nitrate, wire grade, 47 percent ThO2, $2.45-$2.50; nitrate, mantle grade, 47 percent ThO2, $2.50-$2.55; ThO2, ceramic grade, 99.9 percent ThO2, $6-$10; and ThO2, refractory grade, 99.9 percent ThO2, $7-$11. Lindsay Rare Earths, West Chicago, Ill., quotations were as follows, per pound: Thorium salts, 99.9 percent purity, $6 (chloride) -$65 (iodide); nitrate, $2.55-$6; oxide, $7-$20; and oxalate, $4-$6. Quotations on thorium metal in pellets by American Metal Market remained steady at $15 per pound. The pure metal was $65 per pound. FOREIGN TRADE Imports of monazite, largely for the rare-earth content, were slightly reduced from the 1970 level. Australia and Malaysia remained the principal sources of supply. Imports of thorium oxides and nitrates from France increased substantially. Foreign supply of thoriated gas mantles, mainly from the United Kingdom, increased 44 percent in terms of estimated ThO2 equivalent content. There were no thorium metal imports in 1971. Exports of thorium in the form of metal, alloys, and compounds are not available; they are inIcluded with uranium, which comprises the bulk of these exports. 5 The Economist. Nuclear Power's New Joker. V. 240, No. 6681, Sept. 11, 1971, p. 79. Table 2.-U.S. foreign trade in thorium and thorium-bearing materials (Quantity in pounds unless otherwise specified) 4,206 493, 802 ThO2 content e. 504,700 3,448 413,800 427,411 3,373 404,800 383,733 5 382 1,100 Oxide. 442 Oxide equivalent, in gas mantles 2. 4,100 2,514 398,414 10 280 2,481 4,100 409, 110 5,900 1,891 8,692 618,616 1 Includes uranium; thorium and uranium are undifferentiated in official statistics. ? Based on manufacture of 1,000 gas mantles per pound ThO2. WORLD REVIEW Malaysia Australia, Brazil, India, and continued to provide the major share of estimated world production of monazite concentrates in 1971, exclusive of U.S. output, data on which are withheld. Brazil.-The Comissão Nacional de Energia Nuclear (CNEN) increased monazite production by 15 percent in 1970, the latest year for which complete data are available. The CNEN operated monazite workings at Itabapoana (Rio de Janiero) and Cumuruxatiba (Bahia). Monazita e Ilmenita do Brasil, private worked a monazite deposit at Guarapari (Espírito Santo) under contract with CNEN. a concern, A change in Brazil's nuclear energy laws, which relaxed regulations relative to exploration, reportedly was drafted, but no official decision was announced. Canada. The Department of Energy, Mines, and Resources reported thorium reserves in excess of 100,000 tons ThO2 in uranium ores minable at $10 per pound U3Og. There has been no thorium mine production since 1968, but small quantities have been refined to metallurgical-grade ThO2 by Rio Algom for Dominion Magnesium, Ltd., Haley, Ontario, which has produced refined thorium metal, pellets, and powder. Research was underway in modifying techniques to reduce costs and produce high-purity thorium, uranium, and rareearth elements.7 Table 3.-Monazite concentrates: Williams, R. M., and R. M. Berry. Uranium and Thorium in Canada: Resources, Production and Potential. Department of Energy, Mines, and Resources, Ottawa, Ontario. Prepared for Fourth International Conference on Peaceful Uses of Atomic Energy, Geneva, Switzerland, CONF. 710901-172, May 1971, 21 pp. 8 Indian Rare Earths Ltd. 21st Annual Report 1970-71. Bombay, 1971, 32 pp. Dar, K. K., K. M. V. Jayaram, D. V. Bhatnagar, R. K. Garg, (and others). Uranium and Thorium Resources and Development of Techniques for Their Extraction in India. Prepared for Fourth International Conference on Peaceful Uses of Atomic Energy, Geneva, Switzerland, CONF. 710901-233. May 1971, 17 pp. World production, by country In addition to the countries listed, Indonesia and North Korea produce monazite, but information is insufficient to make reliable estimates of output levels. Year beginning April 1 of that stated. Exports. In addition to the monazite listed here, Malaysia also records the export of "other ores of thorium" (not more exactly described) as follows in short tons: 1969-180; 1970-433; 1971-NA. |