Electrodialysis for concentrating cobalt, chromium, manganese, and magnesium from a synthetic solution based on a nickel laterite processing route

Abstract

Due to environmental and human health concerns, the need for cleaner techniques able to extract and recover metals from mining process solutions has been increasing. In this work, the use of electrodialysis for recovering cobalt, magnesium, manganese, and chromium ions from an acid multicomponent solution generated in the nickel laterite processing was evaluated. Values of percent extraction above 98% were obtained for Co2+, Mn2+, and Mg2+ ions. For Cr3+, the greatest percent extraction obtained was 83%. The results of percent concentration of the species showed the same trend: for Cr3+ ions, it was significantly lower than the others. Such difference in the transport of the metals through the membranes may have occurred due to the lower molar concentration, lower diffusion coefficient, and greater Stokes radius of chromium ions. Thus, the transfer of Cr3+ was hindered by the presence of other cationic species. This was also evidenced by the results of current efficiency and energy consumption associated with each species in solution. Lastly, the results of solution pH throughout the experiments and the final condition of the membranes, which were analyzed by SEM/EDS, indicated that the water dissociation phenomenon occurred at their surfaces.