Bureau of Mines / Minerals yearbook: Metals and minerals 1978-79
Year 1978-79, Volume 1 (1978-1979)
Moore, Christine M.
Rare-earth minerals and metals, pp. 735-742 PDF (915.0 KB)
Country1 1976 1977 l978P 1979e Australia Brazil Indiae Korea,Republicof" Malaysia2 Nigeriae SriLanka Thailand r5853 1,775 3,300 10 2,071 20 1 9,377 2,691 3,014 10 2,179 20 e~ 14,864 e2700 3,607 10 1,392 20 220 845 17,000 2,700 3,100 10 2,200 220 800 United States W W W W Zaire 265 106 85 85 RARE-EARTH MINERALS AND METALS 741 Table 4.—Monazite concentrates: World production, by country (Short tons) Total r13,295 17,402 23,743 26,115 e5~timate. "Preliminary. ~ W Withheld to avoid disclosing company proprietary data. ' In addition to the countries listed, Indonesia and North Korea may produce monazite, but output, if any, is not reported quantitatively, and available general information is inadequate for formulation of reliable estimates of output levels. 2Exports. TECHNOLOGY General Motors investigated a new method of fabricating thin curved rare-earth cobalt magnets.4 The process involves two steps to compact rare-earth cobalt powder to precise final shape, including a means of gently restraining the pressed part to allow it to shrink during sintering to its final density of 96% of its theoretical density. The process would reportedly lower inanufacturing costs by eliminating the need for diamond grinding, and reducing material waste and the potential for magnetic breakage. The magnet used in the investigation was made of 75% samarium and 25% mischmetal in a 1:5 rare-earth to cobalt ratio. A chemical engine using a lanthanumnickel alloy powder was investigated to recycle heat from low-temperature industrial process fluids and gases.5 When the powder is heated, the lanthanum-nickel emits hydrogen at sufficient pressure to operate a piston in a cylinder. The new development enables the use of heat of less than 100'C. The U.S. National Aeronautics and Space Administration elected to study processing of neodymium~~-doped laser glass as one of the 14 programs in its materials-processing programs aboard the space shuttle transport.6 The anticipated suppression of crystallization by containerless processing could be used to extend the glass-forming region, which presumably would result in the ability to produce a laser glass with an enhanced lasing-line cross section. An alternative to purification of gadolinium metal by distillation was investigated.7 The study involved the evaluation of LiF-GdF3 and LiF-BaF2-GdF3 as electrnlytes for electrorefining gadolinium. The effects of electrolyte composition and purity, temperature, and current density on the purity of the final product were studied. A review of fused-salt electrowinning of individual rare-earth metals-yttrium metal, and mischmetal-from their respective chlorides and oxides was published. The article included a review of preparation of alloys of yttrium and rare-earth metals by fused-salt electrolysis and electrorefining of yttrium metal.8 The effects of rare earths on the structure and properties of cast irons were reviewed.~ Silicon nitride for high-temperature engineering applications was studied by several groups. Two studies reported using yttria as an additive to improve high-temperature properties of silicon nitride.1° The effects of impurties (Al, Fe, and Ca) in hot-pressing of yttria-doped silicon nitride were discussed." The densification and phase transformation behavior of yttria-doped silicon nitride were studied by comparing its behavior with that of magnesium oxide (MgO)-doped and lithiadoped silicon nitride.'2 A report on current research concerning rare earths in the U.S.S.R. was published.'~ Included in the report were industrial and military uses of rare earths as well as descriptions of ongoing research for the use of rare earths in laser systems, electronic applications, magnetohydrodynamic power generation, refractory applications, and catalysts. Researchers at Oak Ridge National Laboratory developed a cyclic process using ceric oxide to generate hydrogen from water or
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