The recovery of base metals by ion exchange resin

Base metals such as copper, nickel and cobalt are usually recovered by the employment of a selective acid leach followed by electrowinning and/or precipitation techniques. The selective dissolution usually involves a 3-stage sulphuric acid leach incorporating recycling and impurity removal. In this study an alternative process, namely a total leach followed by the selective recovery of the base metals by ion exchange resin, is investigated. The first phase of the project focused on the selective removal of Cu from an electrolyte soution employing a sodium based synthetic resin. It has been found that Cu could selectvely be recovered but that conventional isotherms do not describe equilibrium conditions accurately in all cases. This is explained by the lack of interdependency of equilibrium solution concentrations in the relationships. However, Cu equilibrium is adequately described by a single solute isotherm, manifesting the insensitivity of the resin selected towards the level of Ni and Co in solution. Furthermore, Ni equilibrium conditions were well explained by a Fritz and Schleunder-type multi-component isotherm.