High-purity Cobalt and Nickel Production from Superalloy Scrap.
2nd Int'l Symp --recycling of Metals & Engineered Materials TMS PP 145-157 :145-157
As part of the U.S. Bureau of Mines program to reduce U.S. reliance on foreign supplies of critical and essential metals, Bureau researchers have conducted studies to improve technology for recovering critical and essential metals from superalloy scrap (sas). This report describes a combined pyro- and hydro- metallurgical process for recovering high-purity cobalt and nickel from sas. Pyrometallurgical pretreatment simplifies subsequent hydrometallurgical procedures by altering the scrap matrix through carburization of the more refractory sas constituents. The hydrometallurgical treatment involves electrodissolution of carburized sas anodes in a novel Bureau-developed double-membrane electrolytic cell (dmec). The resulting anolyte is treated by a series of hydrometallurgical procedures to produce a purified cobalt chloride solution. This solution is utilized as a catholyte in a dmec to win high-purity cobalt. Laboratory tests have produced cobalt cathodes meeting National Stockpile Specification P13-R6, for grade a cobalt. Additional test work has produced high-purity nickel in a dmec.
2nd Int'l. Symp.--recycling of Metals & Engineered Materials. TMS, PP. 145-157