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Chromium Recovery from Superalloy Scrap by Selective Chlorine Leaching.

Thomas-JA; Jones-DL; Ettel-VA
U S Patent 1983 Mar; (4):
Chromium is recovered from superalloy scrap by sulfidation to provide a molten matte that is cooled and fragmented. The fragments are leached in an aqueous solution at 85 deg-105 deg c with chlorine while maintaining the redox potential at 250-550 mv. Chromium is retained in the insoluble residue, and all other metals are dissolved as chlorides. Thus, a superalloy matte containing ni 58.1, Cr 8, CO 3.1, Fe 5.2, Mo 0.38, and s 22.5 pct, was ground to - 48 mesh and slurried with an aqueous solution containing ni 80 and cu 10 g/l. Chlorine gas was bubbled through the slurry for 3 h at 80 deg-95 deg c and a redox potential of 550 mv to selectively dissolve the non-cr sulfides. Extractions of metal values into the leach solution were: ni 88, cr 13.4, Co 72.7, Fe 74.1, and mo 57 pct. Chromium is recovered from the residue by an oxidizing roast and smelting with aluminum.
Publication Date
Document Type
Fiscal Year
NTIS Accession No.
NTIS Price
Identifying No.
PAT 4,377,410
Issue of Publication
Source Name
U.S. Patent No. 4,377,410, March 22, 1983; Chem. Abstr. 94:87,877D