Patent ID: 8349208

Claim:
A process for improving copper/iron selectivity in a solvent extraction circuit, the process comprising: contacting an aqueous acidic solution containing dissolved copper and iron ions with a solvent extraction composition contained in a water immiscible organic solvent, the solvent extraction composition comprising: a) one or more orthohydroxyarylaldoximes and/or one or more orthohydroxyarylketoximes; b) one or more selectivity modifiers chosen from one or more phosphinic acid and/or phosphonic acid, and salts and esters thereof; and c) one or more equilibrium modifiers selected from alkylphenols, alcohols, esters, ethers and polyethers, carbonates, ketones, nitriles, amides, carbamates, sulphoxides, and salts of amines and quaternary ammonium compounds, wherein the selectivity modifier is present in a molar ratio of the o-hydroxyoxime from about 0.001 to 0.05, thereby extracting at least a fraction of the dissolved copper and iron ions into the water immiscible organic solvent by forming a metal-solvent extractant complex, and decreasing a copper/iron transfer ratio to improve the copper/iron selectivity.