Reactive extraction of cobalt sulfate solution with D2EHPA/TBP extractants in the pilot plant Oldshue–Rushton column

Abstract

In this study, a pilot plant Oldshue–Rushton extraction column has been proposed to extract and recover cobalt from sulfuric acid leach solution. The effect of D2EHPA and TBP concentration, initial aqueous pH and stripping solvent on the Co(II) extraction was investigated in the batch experiment. The results from batch experiments showed that the D2EHPA/TBP mixed extractant is a suitable choice for cobalt extraction from sulfate solution. In continuous experiments, the effects of variables such as rotor speed, dispersed and continuous phase velocities on holdup, mean drop sizes, extraction and stripping efficiencies were studied. Empirical correlations for prediction of the dispersed phase holdup and mean drop sizes in the literature were compared with the experimental results, and the modified correlations were proposed with reaction condition in the Oldshue–Rushton extraction column. The results of cobalt extraction with D2EHPA/TBP in the extraction column, showed the feasibility of the column for cobalt separation from sulfuric acid leach solution with extraction efficiency of 93% and stripping efficiency of 91.5% at high rotor speed (220rpm).