COMPARISON OF SOLVENT EXTRACTION AND SELECTIVE PRECIPITATION FOR THE PURIFICATION OF COBALT ELECTROLYTES AT THE LUILU REFINERY, DRC

The classic technique to remove impurities in a cobalt stream is selective precipitation, typically followed by re-leaching to produce an advanced electrolyte for cobalt electrowinning. While this method achieves adequate cobalt concentration in the electrowinning circuit, it often leads to unwanted losses during multiple precipitation steps, ultimately resulting in lower recoveries. This study evaluates the benefits of adopting solvent extraction technology as an alternative purification step in the Luilu Process at the Luilu Metallurgical Plant in the Democratic Republic of the Congo, with the objectives of enhancing overall cobalt recovery and ensuring appropriate cobalt concentration in the advanced electrolyte. The findings suggest that the implementation of a solvent extraction-electrowinning process not only improves recoveries but also enhances the quality of cobalt cathodes. However, various factors influencing the transition from the traditional precipitation process at Luilu could impact the success of this approach.