BigPatents India

A process for the extraction of Ni/Co values from an ore or concentrate comprises the steps of subjecting the ore or concentrate to pressure oxidation in the presence of oxygen and an acidic solution containing halide, copper and sulphate ions to obtain a liquor containing Ni/Co values from the resultant pressure oxidation slurry. The liquor is subjected to a selective precipitation treatment to obtain a solid containing Ni/Co hydroxide. The solid is subjected to a Ni/Co leaching stage with an ammonium solution to produce a leach solution containing Ni/Co values and a residue. The Ni/Co values are separated by solvent extraction to produce solutions suitable for electrowinning of Ni and Co. The process also provides for the recovery of precious metals and other metals such as copper