Separation and recovery of copper, nickel, cobalt and zinc in chloride solutions by synergistic solvent extraction

The synergistic solvent extraction (SSX) system consisting of LIX63, Versatic 10 and TBP in Shellsol D70 can be used to separate copper, nickel, cobalt and zinc from strong chloride solutions and to transfer copper and nickel to sulphate media for electrowinning. In the first circuit with the SSX system, over 95% Cu was extracted after a single contact, with the co-extraction of some 12% Ni and negligible Co, Mn and Ca. The loaded organic solution could be scrubbed using water to produce the loaded strip liquor suitable for copper conventional electrowinning. In the second circuit with an SX system consisting of Alamine 336 and TBP in Shellsol D70, over 99% Zn, 87% Co and 43% Mn were extracted at pH 3.5 from the copper depleted raffinate after a single contact. The co-extraction of Ni and Ca was negligible. After stripping, the zinc, cobalt and manganese in the loaded strip liquor could be separated from each other using conventional solvent extraction or ion exchange techniques. In the third circuit for nickel with the same SSX system, over 98% Ni was extracted from the copper-cobalt-zinc depleted raffinate in a single contact. The co-extraction of chloride, manganese and calcium was small and was scrubbed. After stripping using spent nickel electrolyte, the loaded strip liquor would be suitable for conventional electrowinning. The nickel extraction and stripping kinetics were reasonably fast for industrial operation. A process flowsheet to recover copper, cobalt, zinc and nickel from strong chloride leach solutions has been proposed. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.