Separation of cobalt and nickel by non-equilibrium solvent extraction

Abstract

The separation of cobalt and nickel in the ammoniacal sulfate solution by non-equilibrium solvent extraction with a phosphate (P303) as extractant was studied. In the experiment, the effects of equilibrium pH value in aqueous phase, contact time of the two phases, the air-blowing time for feed liquor in the open beaker on percentage extraction of cobalt and nickel and percentage reextraction of nickel from the loaded organic phase with dilute H₂SO₄. etc were studied. The results showed that: Co(II) can be oxidized to Co(III)-ammino-complex by adding (NH₄)₂S₂O₈ or blowing air to the aqueous phase, and Co(III)-ammino-complex is a kind of kinetically inert complex. Its extractive speed is very slow, while the nickel’s is much faster than that of cobalt. By controlling the contact time of the two phases, nickel can be separated from cobalt by non-equilibrium solvent extraction. Then nickel was reextracted from the loaded organic phase with dilute H₂SO₄.

Keywords

non-equilibrium solvent extraction / separation / cobalt / nickel