# US 5,344,479 A · Upgrading copper sulphide residues containing nickel and arsenic > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,344,479 A - Document ID: US5344479A - Status: Granted - Kind: A - Application number: 08/029,513 - Filed: 1993-03-11 - Granted: 1994-09-06 - Earliest claimed: 1992-03-13 - Assignees: Sherritt Gordon Limited - Inventors: Derek G. E. Kerfoot; Rein Raudsepp - Web page: https://patentgrep.com/patent/US5344479A ## CPC - C22B 23/043: {Sulfurated acids or salts thereof} - C22B 3/08: Sulfuric acid {, other sulfurated acids or salts thereof} - C22B 15/0071: {containing sulfur} - Y02P 10/20: Recycling - C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract A process is disclosed for separating and recovering nickel and copper values from a nickel-copper matte which may contain iron and arsenic. Finely divided nickel-copper matte is leached in aqueous sulphuric acid solution under oxidizing conditions at atmospheric pressure and at a minimum temperature of about 80.degree. C. to selectively leach nickel from the matte to produce a nickel sulphate solution having a final pH in the range of about 4.0 to 6.5, preferably about 6.5, and to produce a copper-rich sulphide residue. The copper-rich sulphide residue is separated from the nickel sulphate solution and leached in a closed reaction vessel at a minimum temperature of about 120.degree. C. under a non-oxidizing atmosphere in a sulphuric acid solution containing an effective amount of copper and sulphuric acid to provide a terminal concentration of at least about 2 g/L Cu.sup.2+ and at least about 20 g/L sulphuric acid to produce a nickel sulphate solution containing any iron and arsenic and to produce a low nickel copper sulphide product essentially free of iron and arsenic. ## Claims ### Claim 1 A process for separating and recovering nickel and copper values from a nickel-copper matte which may contain iron and arsenic which comprises: leaching granular nickel-copper matte in an acidic solution at a temperature in the range of about 80.degree. to 100.degree. C. under oxidizing conditions at atmospheric pressure with a deficiency of acid to produce a substantially copper-free nickel sulphate solution and a copper-rich sulphide residue also containing a controlled amount of readily acid-soluble copper, leaching the copper-rich sulphide residue in an acidic solution under non-oxidizing conditions under elevated temperature and pressure to produce a final nickel sulphate solution containing an effective amount of soluble copper and an excess of acid to maintain any iron and arsenic in solution while producing a low nickel, copper sulphide product essentially free of iron and arsenic, said product having a Cu:S mass ratio of at least 3:1. ### Claim 2 A process for separating and recovering nickel and copper values from a nickel-copper matte which may contain iron and arsenic which comprises: leaching finely divided nickel-copper matte in aqueous sulphuric acid solution under oxidizing conditions at atmospheric pressure with a deficiency of acid and at a minimum temperature of about 80.degree. C. to selectively leach nickel from said matte to produce a nickel sulphate solution having a final pH in the range of about 4.0 to 6.5 and to produce a copper-rich sulphide residue containing readily acid-soluble copper; separating the copper-rich sulphide residue from the nickel sulphate solution and leaching said residue in a closed reaction vessel at a minimum temperature of about 120.degree. C. under a non-oxidizing atmosphere in a sulphuric acid solution containing an effective amount of acid-soluble copper to provide a terminal concentration of at least about 2 g/L Cu.sup.2+ to produce a nickel sulphate solution containing any iron and arsenic and to produce a low nickel, copper sulphide product essentially free of said iron and arsenic. ### Claim 3 (depends on 2) A process as claimed in claim 2 in which the low nickel, copper sulphide product has a Cu:S mass ratio of at least 3:1. ### Claim 4 (depends on 2) A process as claimed in claim 2 in which the low nickel, copper sulphide product has a Cu:S ratio in the range of 3:1 to 4:1. ### Claim 5 (depends on 1) A process as claimed in claim 1, in which the copper-rich sulphide residue is leached under a nonoxidizing atmosphere in a sulphuric acid solution containing an effective amount of sulphuric acid to provide a terminal concentration of at least about 20 g/L sulphuric acid. ### Claim 6 (depends on 2) A process as claimed in claim 2 in which the leach under oxidizing conditions is conducted with a deficiency of acid in primary and secondary oxidizing stages, wherein an excess of matte is fed to the primary oxidizing stage and wherein a controlled amount of acid is fed to the second oxidizing stage whereby at least about 5 g/L copper is hydrolyzed to basic copper sulphate. ### Claim 7 (depends on 6) A process as claimed in claim 6 in which the primary stage oxidizing leach is conducted with an excess of matte whereby essentially all copper is precipitated as metallic copper, copper sulphide and basic copper sulphate. ### Claim 8 (depends on 7) A process as claimed in claim 7 in which the oxidizing conditions are produced by sparging the leach solution with at least one of air and oxygen. ### Claim 9 (depends on 8) A process as claimed in claim 8 in which the copper sulphide and basic copper sulphate residue from the leach under oxidizing conditions contains by weight 10-15% sulphur. ### Claim 10 (depends on 7) A process as claimed in claim 7, in which the nickel sulphate solution from the non-oxidizing leach is heated under oxidizing conditions to a temperature of about 150.degree. C. to oxidize any iron to ferric iron and any arsenic to arsenate for precipitation as ferric arsenate, and removing said ferric arsenate precipitate from the nickel sulphate solution.