Cobalt loaded D2EHPA for selective separation of manganese from cobalt electrolyte solution

Manganese from high tenor cobalt electrolyte solution was selectively removed using modified di-(2-ethylhexyl) phosphoric acid (D2EHPA). In this study, D2EHPA was converted to Co-D2EHPA and process parameters such as pH, organic concentration, O/A ratio, kinetics etc. were investigated. Results showed that a significant amount of manganese can be extracted using Co-D2EHPA for the optimum processing of cobalt electrolyte solution at equilibrium pH ~ 3.5 and an O/A ratio of 1. The McCabe–Thiele diagram, constructed from the extraction study of manganese showed that 100% manganese can be extracted through four stages using an O/A ratio of 0.65. From the stripping study, it was found that 100% manganese can be stripped from the loaded organic using 0.4 M H2SO4 in a single contact.

Research highlights
► Manganese was selectively removed from cobalt electrolyte solution by Co-D2EHPA.
► Optimum pH for manganese removal was found to be around 3.5.
► Kinetics of manganese extraction was very fast.
► Cobalt was not co-extracted, hence no losses of cobalt at pH around 3.5.
► 0.4 M H2SO4 was found suitable for 100% stripping of Mn from loaded organic.