Specialized metallurgical processes – compositions for use therei – Processes – Free metal or alloy reductant contains magnesium
Patent
1980-04-15
1981-12-15
Carter, Herbert T.
Specialized metallurgical processes, compositions for use therei
Processes
Free metal or alloy reductant contains magnesium
75108, 423 55, 423 58, 423 61, 423 65, 423 68, 423 23, 423138, 423440, C22B 3432, C01G 3700
Patent
active
043057543
ABSTRACT:
Disclosed is a process for recovering chromium, vanadium, molybdenum, and tungsten from secondary resources such as alloy scrap comprising a refractory metal and base metals such as cobalt nickel, iron, and copper. The scrap is calcined with sodium carbonate in air to convert the refractory metal values to MoO.sub.4.sup..dbd., VO.sub.4.sup..tbd., WO.sub.4.sup..dbd., CrO.sub.4.sup..dbd., and the base metals to water insoluble oxides. A leach of the calcined materials produces a pregnant liquor rich in refractory metals which, after separation of the vanadium, molybdenum and tungsten values, is treated with CO, CHOO.sup.-, CH.sub.3 OH, or HCHO to reduce Cr.sup.+6 to Cr.sup.+3. The carbonate and bicarbonate salts produced as a byproduct of the reduction are recycled to the calcination stage.
As a result of the V, W, and Mo partition, a mixed solid comprising CaO.multidot.nV.sub.2 O.sub.5, CaMoO.sub.4, and CaWO.sub.4 is produced. This is treated with carbonated water or formic acid to selectively dissolve vanadium values which are subsequently recovered by precipitation or extraction. The remaining mixed CaWO.sub.4 and CaMoO.sub.4 solid is treated with H.sub.2 O.sub.2 and sulfuric acid to reject a Mo and W-free CaSO.sub.4 precipitate, and to produce a concentrated solution of tungsten and molybdenum. The W values are selectively precipitated from this solution by decomposing the peroxy complexes. The process has the advantages that a wide variety of different feed materials can be treated, no energy intensive pyrometallurgy is involved, reagent consumption is minimized, and no aqueous effluents are produced.
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patent: 2394362 (1946-02-01), Burwell
patent: 2697650 (1954-12-01), Hixson et al.
patent: 2816015 (1957-10-01), Donaldson
patent: 2839359 (1958-06-01), Dunning
patent: 4072510 (1978-02-01), Smellie et al.
patent: 4173467 (1979-11-01), Rosof
patent: 4207295 (1980-06-01), Kagetsu et al.
Douglas Donald A.
Menashi Jameel
Rappas Alkis S.
Cabot Corporation
Carter Herbert T.
Dropkin Robert F.
Schuman Jack
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