Application of Cyanex extractant in Cobalt/Nickel separation process by solvent extraction

This study presents a detailed review on the advanced hydrometallurgical treatment involving the extraction and separation of Cobalt (Co) and Nickel (Ni) by Cyanex® extractants. The structures, properties and applications of various Cyanex® extractants such as Cyanex®272, Cyanex®301, Cyanex®921, Cyanex®923 and Cyanex®421X were discussed and compared. Cyanex®272 thus proved to be the most appropriate solvent extractant for the separation of Co and Nickel from sulphate and chloride media due to its stability to common oxidant, better physicochemical properties and its ability to avoid gypsum crystallization in stripping-electrowinning circuit. Finally, various solvent extraction (SX) techniques for the extraction and separation of Co and Ni using Cyanex® extractants were discussed as well as newer processes of extraction and separation. Key words: Hydrometallurgy, Cobalt, Nickel, solvent extraction, Cyanex® extractants, Cyanex®272, Cyanex®301, Cyanex®921, Cyanex®923, Cyanex®421X.