Separation of Co(II), Ni(II), Mn(II) and Li(I) from synthetic sulfuric acid leaching solution of spent lithium ion batteries by solvent extraction

BACKGROUND Cobalt, nickel and lithium are crucial in the manufacture of batteries. Therefore, the recovery of these metals from spent lithium ion batteries (LIBs) has attracted much attention because of their benefits in terms of economics and the environment. RESULTS In the present work, the recovery of metals such as cobalt, nickel, manganese and lithium from synthetic sulfuric acid leaching solutions of spent LIBs was performed by solvent extraction using synthetic ionic liquids (ILs) and a mixture of Cyanex 301 and Alamine 336. First, cobalt was selectively extracted over other metal ions by extraction with IL(ALi-SCN). The role of SCN- during the extraction was also investigated, and the extraction reactions of cobalt by both ALi-SCN and Aliquat 336 were verified. The cobalt in the loaded ALi-SCN was stripped by ammonia solution. After adjusting the raffinate pH, extraction with the mixture of Cyanex 301 and Alamine 336 selectively extracted nickel over manganese and lithium. The extracted nickel was completely stripped by 75% aqua regia. Manganese was selectively extracted by IL(ALi-CY) after adjusting the pH of the raffinate. The manganese in the loaded ALi-CY was stripped by HCl solutions. Therefore, three-step solvent extraction resulted in a raffinate containing only lithium. CONCLUSIONS A process was proposed to separate Co(II), Ni(II) and Mn(II) from the sulfuric acid solutions of spent LIBs. The mass balance of continuous experiments indicated that the purity of the stripping solution of Co(II) and Mn(II) was higher than 99.9%. (c) 2020 Society of Chemical Industry