Chromium recovery from superalloy scrap by selective chlorine leaching
AssigneeThe United States of America as represented by the Secretary of the Interior
InventorsJohn A. Thomas, David L. Jones, Victor A. Ettel
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Abstract
To recover chromium and other metals from scrap such as superalloy scrap, the scrap is sulfided to provide a molten matte which is cooled and fragmented, the fragments are leached selectively in an aqueous solution with chlorine at a controlled temperature and with agitation while controlling chlorine flow by redox potential to provide the major portion of the chromium in the leach residue and dissolving other valuable metals present as chlorides and thereafter recovering the chromium from the solid.
Claims10
In a process for separating chromium from other metals in superalloy scrap consisting essentially of chromium alloyed with at least one other metal selected from the group consisting of nickel, cobalt and iron, said scrap being sulfidized with a sulfidizing agent selected from the group consisting of elemental sulfur, nickel sulfide, cobalt sulfide, copper sulfide and mixtures thereof, and melting to form a sulfidized matte, the improvement comprising:
- (i) forming said matte into solid fragments,
- (ii) subjecting said fragments to an aqueous leaching medium,
- (iii) feeding chlorine into said aqueous leaching medium in the presence of a redox couple with agitation at an elevated temperature, said chlorine being fed at a rate to maintain the redox potential below about 600 mV,
- (iv) recovering the undissolved sulfidized chromium from said leach medium,
- (v) recovering chromium metal from said undissolved sulfidized chromium, and
- (vi) recovering the dissolved nickel, cobalt or iron from said leach medium.
Dependencies are inferred from the claim text.