A sulphate solution of cobalt (18.93 g/L Co2+) containing major impurities such as copper (1.35 g/L Cu2+) , iron (0.28 g/L Fetot), zinc (0.70 g/L Zn2+) and manganese (4.83 g/L Mn2+) was purified through the solvent extraction method using two extractants; MEXTRAL and D2EHPA for the removal of copper and for the removal in two stages of a zinc-iron-manganese complex respectively.
The effects of the solutionâ€™s pH, the O/A ratio, the extraction time and the stirring intensity were investigated. The purification extend was enhanced by optimizing these four parameters through Taguchiâ€™s L16 (4^4) experimental.
The final solution obtained through sequential extractions showed a reduction in Cu, Fe, Zn and Mn content of 98.7%, 97.5%, 98.2%, and 80.5% respectively. This study showcased the possibility of obtaining high purity cobalt as a precursor for Lithium Ion Battery applications, representing 49 % of its current global use. The coextraction value of cobalt was estimated at 6.2%.
Keywords: Purification, MEXTRAL 984N, D2EHPA, cobalt, SX