Solvent extraction with DP-8R/LIX 860 mixtures for the selective separation of cobalt and nickel

Abstract

DP-8R and LIX 860 extractans diluted with Exxsol D100 was used to co-extract cobalt and nickel from sulphate aqueous media. The influence of equilibration time, temperature, equilibrium pH and extractants mixture concentration on the extraction of both metals has been studied. It was observed that neither cobalt nor nickel extraction is sensitive to temperature, reaching in both cases the extraction equilibrium within 5 min of contact; however nickel is extracted preferably to cobalt at slightly acidic pH values and also using various extractants mixture concentrations. For a solution containing 1 g/1 each of cobalt and nickel and initial pH value of 5.5, conditions were established for the co-extraction of both metals and selective stripping (with H2SO4) of cobalt and nickel. Using the appropriate extractants concentrations the yield (extraction stage) for both metals is near 90 %, whereas the percentage of cobalt and nickel stripping is almost also quantitative.