Synergistic extraction of Co(II) over Ni(II) from chloride solutions by a mixture of Cyanex 301 and LIX 63

It is difficult to separate Co(II) and Ni(II) by extraction with single Cyanex 301 from acidic solution. The synergistic extraction of Co(II) over Ni(II) from aqueous chloride solutions was studied using a mixture of Cyanex 301 and LIX 63. A significant synergistic extraction of Co(II) with the synergistic enhancement factor of 191 was obtained by adding LIX 63 to Cyanex 301, while Ni(II) extraction was little affected. The highest separation factor of 10 was obtained at an optimum composition of the mixture. The extraction reactions with this mixture were proposed on the basis of slope analysis. The extracted species of Co(II) and Ni(II) was found to be Co(HA2)2·HB and Ni(HA2)2, respectively. Effective stripping of Co(II) and Ni(II) was attained by using different concentrations of HCl solution. It is feasible to apply this mixture for the separation of Co(II) and Ni(II) from the leach liquor of laterite ore. © 2017 The Korean Society of Mineral and Energy Resources Engineers (KSMER).