HYDROMETALLURGISKT FOERFARANDE FOER UTVINNING AV ICKEJAERNMETALLER

1510287 Recovery of cobalt, copper and nickel SHERRITT GORDON MINES Ltd 7 May 1976 [21 May 1975] 18923/76 Heading C1A Metal values are recovered from materials containing one or more of copper, cobalt and nickel together with insufficient sulphur in the form of sulphide to combine stoichiometrically with the non-ferrous metals as sulphates; the recovery being achieved by forming a slurry of finely divided particles of the material in an aqueous solution substantially devoid of free ammonia and containing from 25 to 300 gms per litre of at least one of (NH 4 ) 2 SO 4 , Na 2 SO 4 or NiSO 4 the pH of the slurry is adjusted to a value within the range 4À5 to 6À5 and the slurry is then reacted in the presence of a free oxygen containing gas at 80 to 180‹C. under a pressure sufficient to maintain an oxygen partial pressure of at least 5 p.s.i. until the metals are converted into their hydroxides when the slurry is cooled to below 100‹C. and the pressure reduced to atmospheric, the pH of the cooled slurry is adjusted to a value from 3 to 4À5 by addition of H 2 SO 4 , and the hydroxides are dissolved by agitation and the solution containing the dissolved non-ferrous metals is separated from the acid-treated slurry. The starting material may also contain the precious metals, i.e. Ag, Au, Pt or Pd, and these metals are recovered in a concentrated form in the undissolved residue.