Patent ID: 7422621
Filing Date: 2008-09-09
Classification: C22B,Y02P

Abstract:
1. A method for concentrating precious metals in a leaching residue containing pyrite, elementary sulfur, precious metals and gangue, discharged from a copper hydrometallurgical process, said method comprising: (1) providing the leaching residue produced from leaching a copper sulfide ore in an acidic, aqueous, chlorine-based solution, (2) a pyrolysis step in which the leaching residue is thermally treated at 550° C. or higher in a non-oxidative atmosphere, to produce a calcined ore containing pyrrhotite, precious metals and gangue, and (3) a re-leaching step in which the calcined ore is re-leached in an acidic, aqueous solution, to be separated into a re-leaching residue and iron-leached liquor, the former containing elementary sulfur, precious metals and gangue, wherein the acidic, aqueous solution for the re-leaching step is a copper-containing leaching liquor discharged from a leaching step of leaching a copper sulfide ore with an acidic, aqueous, chloride-based solution in the copper hydrometallurgical process.