| 摘要 |
<p>REFRACTORY METAL RECOVERY PROCESS 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 Mo04=, VO4?, W04=, and Cr04= 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 C0, CHOO-, CH30H, or HCHO to reduce Cr+6 to Cr+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 Ca0?nV205, CaMo04, and CaW04 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 CaW04 and CaMo04 solid is treated with H202 and sulfuric acid to reject a Mo and W-free CaS04 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.</p> |
