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Recovery of Critical Metals from Superalloy Scrap by Matte Smelting and Hydrometallurgical Processing.
MISSING :11 pages
As part of the U.S. Bureau of Mines program to reduce the nation's reliance on foreign supplies for critical metals, a procedure was devised to separate and recover critical metals from mixed and contaminated superalloy scrap. The process uses both pyrometallurgical and hydrometallurgical methods to treat the scrap. The mixed scrap is converted to a matte containing 4 to 7 pct S by adding s directly to the molten metal. This matte is then granulated and ground to a minus 35-mesh particle size and leached with an HCl-Cl2 solution. This process takes essentially all the Ni, CO, Cr, Fe, Al, and mo into solution in a 3-h leach, leaving W, Ta, Ti, and Nb (Cb) in the residue. The mo is recovered from the chloride leach solution by solvent extraction, and the cr and fe are recovered together by precipitation. The ni and CO can be recovered individually by an existing solvent extraction-electrowinning process. The w is recovered by a caustic leach of oxidized cl2 leach residue.
IH; Report of Investigations;
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division