Simultaneous solvent extraction of cobalt and nickel in the presence of manganese and magnesium from sulfate solutions by Cyanex 301

The simultaneous extraction and separation of Co(II) and Ni(II) from manganese and mgnesium sulfate solutions have been carried out using the thio-organophosphinic extractant Cyanex 301, diluted in Exxsol D-80. Statistical design and analysis of experiments were used in order to determine the main effects and interactions of the solvent extraction factors, which were the extraction pH at equilibrium, temperature, extractant concentration and organic to aqueous phase ratio. A statistically designed experiment was also carried out in order to study the stripping of the cobalt- and nickel-loaded Cyanex 301 organic phase by hydrochloric acid solution. The Slope analysis method was used to determine the nature of the cobalt and nickel complexes extracted. The number of stages required for both extraction and stripping processes of cobalt and nickel was also evaluated. The results of the continuous counter current, mini plant tests demonstrated the simultaneous recovery of cobalt and nickel from manganese and magnesium sulfate solution.