Separation of Cobalt, Nickel, and Copper from Synthetic Metallic Alloy by Selective Dissolution with Acid Solutions Containing Oxidizing Agent

Abstract

ABSTRACT The dissolution behavior of Co, Ni, and Cu and the metallic mixture in acid solutions like HCl, H2SO4, CH3SO3H, and CH3COOH and their mixture with H2O2 was investigated. The effect of parameters such as acid and H2O2 concentration, pulp density, reaction temperature, and time on the dissolution of metals was studied. The CH3SO3H-H2O2 system showed highly selective leaching ability for Co over Ni and Cu from their metallic mixtures at low temperature. Under the optimum condition, Co can be selectively dissolved over Ni and Cu within 30 min at 20°C with 95.0% purity. Ni from the residues was selectively leached over Cu by either H2SO4 solution or the mixture of H2SO4 and H2O2 with above 99.9 and 95.6% purity in either method. A process has been proposed for the separation of the three metals by selective leaching from metallic alloys. This process shows some economic and environmental advantages such as significant decrease in the consumption of acids, reaction temperature, and time. Separation of metals by selective leaching resulted in solutions with high purity and obviation of the subsequent separation steps, which has a favorable effect on the process economics and environment. Thus, the process can be applied to the real operation.