Bureau of Mines / Minerals yearbook: Metals and minerals 1978-79
Year 1978-79, Volume 1 (1978-1979)
Kirk, William S.
Thorium, pp. 907-913 ff. PDF (788.7 KB)
Thorium By William S. Kirk' Monazite, the principal source of thorium, continued to be recovered as a byproduct at two locations in Florida throughout 1978 and most of 1979. However, most of the thorium compounds used by the domestic industry during 1978 and 1979 came from imports or existing company stocks. No major developments occurred in the nonenergy uses of thorium, which include mantles for incandescent lamps, hardeners in magnesium alloys, refractories, welding rods, and electronics. The only commercial thorium-fueled, high-temperature, gas-cooled reactor (HTGR) located at Fort St. Vram, Cob., with a capacity of 330 megawatts, continued to run at 70% capacity in. 1978 and 1979. The experimental thorium-fueled, light- water breeder reactor (LWBR) at Shippingport, Pa., continued to operate in 1978 and 1979. The U.S. Geological Survey, assisted by the Bureau of Mines, completed its U.S. Department of Energy (DOE) sponsored thorium resources evaluation program in 1979. Legislation and Government Programs.—The Tokyo round of negotiations was completed in 1979 resulting in new tariff agreements for minerals, including thorium, with the developed nations of the world. The agreements placed most nations on a most-favored-nation basis with generally lower rates to be phased in, or staged, over an 8-year period beginning January 1, 1980. DOMESTIC PRODUCTION Exploration.—The U.S. Geological Survey, in cooperation with the Bureau of Mines, concluded a study of the thorium resources of the United States.2 The resulting paper, prepared on behalf of DOE, is the first definitive study of these resources in the United States. Thorium resources, in the higher grade and better known deposits, were assessed in (1) veins, (2) massive carbonatites, (3) stream placers of North Carolina and South Carolina, and (4) disseminated deposits. Thorium resources for the first three categories were divided into reserves and probable potential resources. These were then separated into the following cost categories: (1) the amount of Th02 producible at less than $15 per pound, (2) the amount producible at between $15 and $30 per pound, and (3) the amount producible at between $30 and $50 per pound. The type of mining and milling needed at each deposit determines the capital, operating, and fixed costs of both mining and milling. Costs start with the clearing of land and are carried through to the final product, which for all deposits is Th02. The Bureau of Mines published a report describing three cost estimating models developed as guides for assigning costs to the recovery of thorium from domestic deposits.~ These models have been used by the Geological Survey and DOE in evaluating the principal thorium resources of the United States. The engineering and cost models were developed for the recovery of thorium contained in vein deposits, fluviatile placer deposits, and massive carbonatile deposits. The models can be used to determine the capital investment and operating expense required to mine and beneficiate thoriumcontaining ores from individual deposits. This cost, based on state-of-the-art mine and metal technology, is adjusted for variation in the grade, depth, and shape of the ore body and desired rate of production. The Geological Survey also published a paper describing the geology and mineral 907
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