GB1460989A - Hydrometallurgical method for recovering copper values from copper concentrates - Google Patents

Abstract

1460989 Recovering copper values NORANDA MINES Ltd 23 Aug 1974 [30 Aug 1973] 37176/74 Heading C1A Copper values are recovered from copper concentrates by dispersing the concentrate in an aqueous leach solution containing Cl- or Brions to form a slurry, carrying out the leaching operation of the slurry at an elevated temperature and under an overpressure of oxygen with the concentration of the Cl- or Brions being such as to transform a major proportion of the copper values present into a solid basic copper sulphate, separating the leach residue containing said basic copper sul phate from the leach solution and recovering coppervalues from said residue. The source of halogenions in the leach solution may be HCl, NaCl, CaCl 2 NH 4 Cl HBr, NaBr or KBr and the leach solution preferably contains a source of sulphate ions. The preferred leach solution is a mixture of HCl and H 2 SO 4 , said mixture containing at least 25% by weight of HCl. The molar ratio of halogen ions to copper ions in the slurry is preferably greater than 0À08 : 1 and the total amount of acid in the slurry is preferably such that the molar ratio H<SP>+</SP> : Cu is between 0À15 and 0À65 : 1.0. The leaching is suitably carried out at a temperature between 125‹ and 160‹ C. under an oxygen partial pressure of at least 180 p.s.i.g., preferably 200 to 300 p.s.i.g. with a pH of between 2À5 and 4À5. The leaching is suitably continued for a period sufficient to effect at least 90% and preferably over 97% conversion of Cu. The concentrates, which may be chalcopyrites, may be dispersed in the leach solution in as-received condition or may be ground for 30 minutes prior to dispersion. Upon separation of the leach residue, the residue is washed to eliminate remaining traces of Cl- or Brions and the values may be recovered from the residue by either selective dissolution of copper in an ammonia or ammonium sulphate solution followed by solvent extraction from the ammoniacal liquor, stripping with H 2 SO 4 and electrowinning from said acid solution or by leaching the residue in dilute H 2 SO 4 and electrowinning. The leach solution is suitably recycled. The leaching operation is preferably controlled so that not more than 40% of the converted copper goes into solution. The residue also contains elemental sulphur and any iron that was in the concentrate.