Solvent Extraction of Cobalt and Zinc from Sulphate Solutions using Phosphoric, Phosphonic and Phosphinic Acids

摘要

Extraction and separation of cobalt and zinc from a sulphate solution was carried out using 0.04M NaD2EHPA, NaPC88A and NaCyanex 272. The percentage extraction and D_(Zn) values increased with the equilibrium pH. D2EHPA as its sodium salt was found to be the most suitable extractant for the separation of metal ions. One mole of metal ion was associated with the release of one mole of H~+ ion. Separation factor for cobalt and zinc increased with equilibrium pH and was the highest at pH 5.65. Extraction and stripping of zinc could be achieved in two counter-current stages at equal phase ratio. Between H_2SO_4 solution and zinc spent electrolyte (containing the same concentration of H_2SO_4), H_2SO_4 was found to be a better stripping agent. Extraction and stripping of cobalt could be achieved in two counter current stages at equal phase ratio. Cobalt from the loaded D2EHPA could be stripped with 2 kg/m~3 H_2SO_4 solution concentration.