Förfarande för återvinning av nickel och koppar ur sulfider

摘要

1283588 Recovering sulphur and metal values from sulphides INTERNATIONAL NICKEL CO OF CANADA Ltd 4 Aug 1969 [3 Aug 1968] 38993/69 Heading C1A Cu and/or Ni sulphides substantially free from Fe are slurried with a solution containing at least 2 g./l. of Fe as Fe sulphate and H 2 SO 4 at a temperature of from 80 to 150‹ C. under a partial pressure of O 2 of at least 2 atmospheres such that the sulphides dissolve as sulphates and elemental sulphur is released. The starting material may be obtained by slurrying a sulphide material containing Cu and Ni and optionally Co and Fe with a solution containing CuSO 4 and H 2 SO 4 at a pH less than 5 and at a temperature of 100-250‹ C. under autogenous pressures such that the Ni, Co and Fe dissolve as sulphates to leave a residue of Cu sulphide. The CuSO 4 /H 2 SO 4 solution may be part of that obtained by the oxidative leaching. Some Ni may initially be removed as Ni carbonyl by treatment with CO at 5-100 atmospheres and a temperature of from 50-200‹ C., and Fe may be removed by smelting and oxygen blowing until the Cu : S wt. ratio is at least 3À5 : 1, and the melt is then drastically cooled. Cu may be recovered from the CuSO 4 soln. by electrodeposition (spent electrolyte being used in the oxidative leaching), cementation, or precipitation with alkali or H 2 . The soln. of Co, Ni and Fe sulphates obtained in the first stage leaching may be treated with Ca(OH) 2 or NH 4 OH and O 2 to ppt. Fe(OH) 3 , any Cu may then be removed by electrodeposition or by pptn. with H 2 S or H 2 , Co may be pptd. as Co(OH) 3 (which may be redissolved in HCl and purified by ion-exchange), and the remaining NiSO 4 soln. may be treated with Na 2 CO 3 to ppt. NiCO 3 or with H 2 S to ppt. NiS, which may be calcined to NiO. Precious metals may be recovered from the S ppt. by melting and filtration or by solvent leaching e.g. with perchloroethylene.