As part of the U.S. Bureau of Mines program to reduce the U.S. Reliance on foreign suppliers of critical metals, research has been conducted to develop technology for the recovery of critical metals from hardface alloy grinding waste, a form of superalloy scrap. This report describes a hydrometallurgical process for the recovery of values such as cobalt, chromium, manganese, nickel, and tungsten. The process involved deoiling the grinding waste followed by chloride-based dissolution of the deoiled material. A high-grade calcium tungstate product was recovered from the resultant leach residue. Iron, cobalt, manganese, and nickel chlorides were sequentially recovered from the leach liquor by solvent extraction. Market-grade cobalt chloride, manganese chloride, and nickel chloride products can be produced directly from the strip liquors. The final raffinate was a relatively pure chromic chloride solution that compares favorably with commercial solutions.
Miner., Met.,and Mater. Soc., TMS Tech. Paper A89-11, 1989, 20 PP.