Enhancing cobalt recovery from Li-ion batteries using grinding treatment prior to the leaching and solvent extraction process

Abstract

The growing of cobalt demand for electric vehicle batteries and various applications associated with the no cobalt ores makes the European Union consider it as a critical metal. This causes the search for new sources to meet the demand. Several studies have been explored battery recycling to promote the circular economy. On the one hand, acid leaching has been widely studied for cobalt recovery, but on the other hand, the grinding step is not well explored in the literature, which must increase metals release and further recovery. For this reason, the aim of the present work is to provide new insights on cobalt extraction from Li-ion batteries evaluating from the grinding step to the selective separation. Different grinding techniques were studied to ground the scrap: hammer, knife, and ceramic balls were evaluated on dismantling considering cobalt release. Ultrasound washing was evaluated to decrease the particle size distribution of ground material. Leaching experiments were carried out exploring different leaching agents (H2SO4, HNO3 and HCl with and without H2O2) and conditions (time, temperature and pH). Selective cobalt separation was performed using Cyanex 272 1 mol/L in kerosene. Results have shown that knife mill was the only one to ground the batteries. The best efficiency for cobalt leaching was obtained using H2SO4+H2O2 at pH 3.0 and 50 °C. Considering all hydrometallurgical processing – leaching-solvent extraction – 91 % of cobalt was recovered.