Patent ID: 7727496

Claim:
A method of extracting impurity metal ions including any one or more of cobalt, copper, zinc and manganese from an impure valuable sulphate stream in the form of a cobalt/nickel-containing stream in a solvent extractant circuit, the method comprising the steps of: a) contacting the cobalt/nickel-containing stream in a cobalt solvent extraction circuit with an organic solvent and producing a cobalt-loaded organic extractant and a purified nickel-containing stream; (b) stripping cobalt from the cobalt-loaded organic extractant and producing a stripped organic extractant; (c) directly after step (b), loading the stripped organic extractant with nickel from a part of the purified nickel-containing stream from step (a) to pre-equilibrate the organic extractant; and (d) providing the pre-equilibrated organic extractant as the organic solvent for contacting with the cobalt/nickel-containing stream in step (a).