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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)


Page 907

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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