Bureau of Mines / Minerals yearbook: Metals, minerals, and fuels 1972
Year 1972, Volume 1 (1972)
Sondermayer, Roman V.
Thorium, pp. 1201-1208 PDF (856.3 KB)
1206 MINERALS YEARBOOK, 1972 ings output of the concentrator is processed through the plant. About 22,000 tons per day of dry solids represents the average quantity fed to the plant. Uranothorianite concentrate, obtained by gravity concentration and containing approximately 5% U308, 14% Th02, and 65% Zr02, was processed through the chemical extraction plant. Thorium and uranium are extracted by leaching with hot nitric acid. The liquor containing thorium and uranium is then treated in a solvent extraction circuit and the product calcined. A new feature of the process is the provision of facilities for recovery of nitric acid and thorium from the barren solution or raffinate from the solvent extraction. Since the ThQ2:U308 ratio is on the order 2.5:1, thorium could become an important byproduct.8 United Kingdom.—The United Kingdom Atomic Energy Authority won a contract to design and supply a solid moderator reactor (SMR) for the THTR under construction at Schmehausen in West Germany. The function of the SMR is to facilitate reloading of the THTR.~ Venezuela.—The Government announced a discovery of thorium in the Cerro Impacto Codesur area of southern Venezuela. The area was reserved for exploration by the State through a Governmentowned corporation called Promocion Del Desarrollo Del Sur de Venezuela (Prodesur). Information on size of deposits and reserves was not reported. TECHNOLOGY Energy and metallurgical applications together with extraction techniques were the principal subjects of studies related to thorium during 1972. Most of the research was basic, and industrial utilization of results was not imminent. Nonenergy.—At the Elliot Lake uranium mine in Ontario, Canada, large volumes çf waste materials contain thorium. An investigation was conducted to find a solvent extraction process for the coextraction of uranium and thorium. The new approach would. replace the present precipitation procedure for thorium elimination, which is costly because of neutralization and coprecipitation losses of the rare earths. Results indicated that high-purity thorium sulfate can be produced with the ion exchange-neutralization route. In addition, increased revenue would result if thorium is recovered.10 Metallurgical research was directed toward studies determining the effects of thorium and thorium compounds on physical and chemical properties of alloys, mostly high-temperature alloys, in different environments. One investigation indicated that addition of Th02 to high-temperature nickel or cobalt-base superalloys slows oxidation. In an oxidation process induced by Na2SO4, the presence of ThO2 in a nickelchromium alloy promoted selective oxidation of chromium, and the growth rate of the chromium oxide layer was approximately one order of magnitude less than that ' for growth of chromium oxide in simple nickel chromium alloys.11 The application of fine wires as highstrength structural components requires a better undertanding of differences of creep behavior. The creep properties of fine, recrystallized tungsten-thorium oxide (1% ThO2 by weight) wires were studied over the temperature range 1,800° to 2,750° C. The creep behavior of tungsten-thorium alloy wire depends on grain structure, temperature, and stress. The study showed that the creep behavior of fine wires was not affected by geometry, and identical results could be expected for larger diameter specimens.12 Ronson Metals Corp.'s "CerAlloy 400," made of approximately 80% thorium, 15 mischmetal, and 5% aluminum, was used in plutonium-powered pacemakers (small devices, surgically implanted in body, regulating the rhythm of heart beat). The new pacemaker should operate for 10 years 8 Ne!, V. Pa1abora~s New Heavy Minerals Plant Adds Uranium Concentrate to the Recovery List. Eng. and Mi J., v. 173, No. 11, November 1972, pp. 186—187. 9 Chemistry and Industry. UKAEA Win Reactor Contract. No. 3, Feb. 5, 1972, p. 104. 10 Ritcey, H. C., and B. H. Lukas. Co-extraction of Uranium and Thorium. J. of Metals, v. 24, No. 4, April 1972, pp. 39—44. 11 David, H. H., H. C. Graham, and G. F. Uhlig. Oxidation of Na2SOS-Coated Ni-2OCr- 2ThO2. Met. Trans., v. 3, No. 12, December 1972, pp. 3247—3257. 12 Moon, D. M. Creep of Fine Wires of ' NTh02 Alloys. Met. Trans., v. 3, No. 12, December 1972, pp. 3097—3102.
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