Patent ID: 6379636
Filing Date: 2002-04-30
Classification: C22B

Abstract:
A hydrometallurgical sulfuric acid leaching process for the extraction of nickel and cobalt from nickeliferous laterite oxide ore that comprises:a. providing an aqueous pulp of nickeliferous oxide ore with a low magnesium content; b. leaching the aqueous pulp at a temperature of at least about 200Â° C. and at an elevated pressure with an addition of sulfuric acid at least sufficient stoichiometrically to effect the leaching of contained nickel and cobalt and thereby provide a leach liquor discharge of nickel sulfate, cobalt sulfate and a leach residue, wherein the leach liquor contains between 76 and 114 g/L of sulfuric acid; c. adding controlled quantities of a raw, high magnesium containing nickeliferous oxide ore to the leach liquor from step (b) at atmospheric pressure to yield a final neutralization slurry, wherein (i) the raw ore is added at temperatures of from 80Â° C. up to the atmospheric pressure boiling point of the final neutralization slurry, (ii) sufficient agitation and time are provided to effect the extraction of nickel and cobalt from the raw ore, wherein between 73 and 94% of the nickel present in the nickeliferous laterite oxide ore is extracted, and (iii) a reducing agent is not added to the final neutralization slurry to control its oxidation/reduction potential; and d. adding a sufficient amount of a precipitating agent selected from the group consisting of alkali metal ions, ammonium ions, and mixtures thereof, to the pulp of step (a), leach liquor of step (b), or final neutralization slurry of step (c) to precipitate ferric iron as jarosite.