Solvent extraction of cobalt and zinc from sulphate solutions using phosphoric, phosphonic and phosphinic acids

K.C. Nathsarma* and P.V.R. Bhaskara Sarma

Hydrometallurgy Division, Regional Research Laboratory Bhubaneswar-751 013, Orissa, India

Received 10 April 2002; accepted 15 February 2003


Extraction and separation of cobalt and zinc was studied from a sulphate solution using NaD2EHPA, NaPC88A and NaCyanex 272 of 0.04 M concentration. The percentage extraction and DZn values increased with increasing equilibrium pH. Of the three extractants studied, NaD2EHPA was found to be the most suitable extractant for the separation of metal ions. Separation factor for cobalt and zinc increased with increasing equilibrium pH and was the highest (3394) at pH 5.65. Quantitative extraction (at equal phase ratio) and stripping (at A:O=1:5) of zinc could be achieved in two counter-current stages. Between H2SO4 solution and zinc spent electrolyte (containing the same concentration of H2SO4), the former was found to be a better stripping agent for zinc. Extraction (>99%) of cobalt could be achieved in two counter current stages at equal phase ratio and the metal could be stripped quantitatively in two counter-current stages from the loaded solvent with H2SO4 solution of 2.0 kg/m3 concentration.

Keywords: Solvent extraction; Cobalt; Zinc; D2EHPA; PC 88A; Cyanex 272 Counter-current simulation

* Corresponding author
   E-mail : nathsarma@rrlbhu.res.in