Bureau of Mines / Minerals yearbook: Metals and minerals 1977
Year 1977, Volume 1 (1977)
Kahn, Martha L.
Thorium, pp. 923-929 ff. PDF (754.1 KB)
Thorium By Martha L. Kahn1 Monazite, the principal source of thorium, continued to be a byproduct of titanium and tin mining and was recovered domestically for its rare-earth content in Florida. Thorium-containing residues remaining after extraction of rare earths from monazite were stored for future use. Practically all thorium compounds used by the domestic industry during 1977 came from existing company stocks or imports. No major developments occurred in the nonenergy uses of thorium, which include mantles for incandescent lamps, hardeners' in magnesium alloys, refractories, and electronic and chemical applications. The future prospects for thorium's use in nuclear fuels remained uncertain in 1977. The only commercial thorium-fueled, hightemperature, gas-cooled reactor (HTGR), located at Fort St. Vram, Cob., with a capacity of 330 megawatts, reached almost 70% of power capacity in 1977. The experimental thorium-fueled, light-water breeder reactor (LWBR), at Shippingport, Pa., reached full capacity by yearend. The U.S. Geological Survey (USGS) began an evaluation of thorium resources recoverable at costs of $30 and $50 per pound. DOMESTIC PRODUCTION Exploration—Five deposits ' of heavy minerals containing thorium were reported~ in: ancient beach sands in Charleston County, S.C., by the USGS. An aerial geophysical survey and preliminary ground checks indicated that the deposits contain 2 million tons of potentially economic heavy minerals, including monazite. The three largest deposits are 9 miles north of McClellanville, 9 miles southwest of Charleston, and 12 miles southwest of Charleston. Buttes Gas and Oil Co. continued feasibility and pilot-plant studies of its southwestern Colorado titanium prospect.3 The ore mineral perovskite reportedly contains significant amounts of thorium that could be recovered. The USGS began studying thorium resources available at $30 and $50 per pound for the U.S. Department of Energy (DOE).~ The first phase of the study, to be completed in May 1978, was to assess better known deposits. The U.S. Bureau of Mines provided mining and milling cost analyses for the USGS study. The principal deposits to be studied included the vein deposits of the Wet Mountains, Cob., Lemhi Pass, Idaho, and the Bokan Mountains, Ala.; massive carbonatites of the Powderhorn Pass district, Cob., and Mountain Pass district, Calif.; deposits in fractured and brecciated rocks in Wyoming and illinois; Piedmontstream placers of the Carolinas; and current monazite-producing areas in northern Florida. Coproducts were also to be considered. Mine Production.—Monazite, a thoriumcontaining, rare-earth, phosphate mineral, was produced as a byproduct of processing beach sands for titanium minerals in 1977. Two mines in Florida, Humphreys Mining Co., near Hilliard,, and Titanium Enterprises, near Green Cove Springs, were the only domestic producers of monazite. Humphreys Mining Co. continued to truck wet titanium concentrates from its mine in Florida to the company's dry plant at Folkston, Ga. Refinery Production—In 1977, there was only one domestic firm, W. R. Grace & Co., Davison Chemical Div., at Chattanooga, Tenn., with facilities for processing large tonnages of monazite. Although W. R. Grace did not produce any thorium compounds from monazite for sale, thorium was extracted from monazite during the refining of rare-earth elements and stored. 923
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