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Treatment of Superalloy Scrap for Separation of Metals.
Atkinson-GB; Laverty-PD; Desmond-DP
Paper in Refractory Metals: Extraction Processing & Applications TMS PP 15-29 :15-29
The U.S. Bureau of Mines treated mixed and contaminated superalloy scrap by pyrometallurgical methods to obtain a feed for hydrometallurgical treatment to separate metal values. Pyrometallurgical processing included melting with aluminum, treatment with zinc, and atomization. Best hydrometallurgical results were obtained by leaching zinc-treated or atomized scrap with hcl-o2 at 95 deg c and 50 psig o2. This dissolved 98 pct of the al, CO, cr, cu, fe, mn, ni, and zn, and rejected 98 pct of the mo, Nb, ta, ti, w, and zr as an insoluble refractory residue. Chlorine was successfully substituted for hcl to leach zn-treated scrap but was unsuccessful for leaching atomized scrap. The leaching solution was treated by ph adjustment and hydrothermal precipitation at 200 deg c for 4 h to remove al, cr, fe, and other contaminants as a filterable precipitate. Cobalt and nickel would be recovered by solvent extraction and electrowinning. Recovery of chromium as a ferroalloy was demonstrated.
Paper in Refractory Metals: Extraction, Processing & Applications. TMS, PP. 15-29
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division