Cuprous hydrometallurgy. Part VIII. Solvent extraction and recovery of copper(I) chloride with organic nitriles from an iron(III), copper(II) chloride, two-step oxidative leach of chalcopyrite concentrate

Abstract

Water-immiscible organic nitriles selectively extract copper(I) chloride as CuCl from aqueous chloride solutions. The distribution coefficients for the extraction of metal chlorides are in the order Ni2+ ≪ Fe2+ < Na+ < Cu2+ ≈ Co2+ < Cu+ ≤ Fe3+. The equilibrium Cu2+ + Fe2+ ⇌ Cu+ + Fe3+ lies strongly to the right in nitrile solutions containing a small amount of water. When volatile nitriles containing some water are used as extractants, CuCl may be recovered from the organic phase by stripping the solvent with steam. Pure CuCl, suitable for reduction to electrolytic-grade copper, is precipitated from the residual aqueous phase. A process is demonstrated for the recovery of pure CuCl from chalcopyrite concentrate, in which a two-stage, iron(III), copper(II) chloride leach is used to maximize the amount of CuCl relative to CuCl2 formed in solution. © 1980.