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Production of molybdenum metal by magnesium reduction of molybdenum oxides.

Campbell-TT; Block-FE; Andersen-ER
Albany, OR: U.S. Department of the Interior, Bureau of Mines, RI 5934, 1962 Jan; :1-22
This investigation was undertaken by the Bureau of Mines to determine if high-purity ductile molybdenum of uniform quality can be prepared by bomb reduction techniques. Molybdenum trioxide (MoO3) and mixtures of molybdenum dioxide (MoO2,) and trioxide were reduced by magnesium in closed steel bomb reactors. Very high pressures in excess of 5,000 p.s.i. developed during magnesium reductions of MoO3. The addition of calcium oxide to the bomb charges caused a significant reduction in pressure. Reaction efficiencies higher than 95 percent were obtained during magnesium reductions of either MoO3 or mixtures of MoO2 and MoO3, but high pressures were encountered when the charges contained from 30 to 60 percent MoO2. Reaction efficiencies were usually low (less than 80 percent) when the bomb charges contained more than 40 percent MoO2. The charges with the best composition considering operating pressure, yield, and purity contained from 10 to 30 percent MoO2. The addition of small amounts of carbon to the reaction charges was helpful because some deoxidation occurred during the reduction and also during subsequent arc-melting of the regulus metal. The purity of the bomb-reduced, arc-cast molybdenum metal ranged from 99.2 to 99.8 percent and in some instances the metal contained as little as 5 parts per million oxygen. The regulus metal can be collected as a cast ingot in the bomb. These rough ingots were joined into consumable electrodes that were subsequently arc-melted into sound arc-cast ingots. The ductility of the arc-cast, bomb-reduced metal was determined by fabrication tests. Ingot sections were impact forged through reductions of over 50 percent. Workability of the metal could not be correlated with chemical analyses or hardness data; however, large amounts of carbon and oxygen did harden and embrittle the metal.
Molybdenum-compounds; Metal-compounds; Metal-refining; Metallurgical-processes
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Report of Investigations
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Albany, OR: U.S. Department of the Interior, Bureau of Mines, RI 5934
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division