Separation and recovery of cobalt(II) and nickel(II) from sulphate solutions using sodium salts of D2EHPA, PC 88A and Cyanex 272

Abstract

Separation and recovery of divalent cobalt and nickel ions from sulphate solutions containing 0.01 M metal ions each and 0.1 M Na 2SO 4 have been carried out using 0.03, 0.05 and 0.06 M sodium salts of D2EHPA, PC 88A and Cyanex 272 in kerosene. The percentage extraction of metal ions increased with increasing equilibrium pH. Cobalt was preferentially extracted over nickel with the extractants; however, 0.05 M NaPC 88A and NaCyanex 272 were found to be suitable for the separation study. The highest separation factor was achieved with 0.05 M NaCyanex 272 at equilibrium pH 6.85. Recovery of cobalt from cobalt–nickel bearing solution was achieved with 0.05 M Cyanex 272 and PC 88A at equal phase ratio followed by their stripping with 0.02 M H 2SO 4 at O:A ratio of 2:1. Nickel was extracted from the cobalt-free raffinate in two stages at equal phase ratio with PC 88A and Cyanex 272 followed by their stripping with 0.02 M H 2SO 4 at O:A ratio of 4:3 and 2:1, respectively.