Partition studies on cobalt and recycling of valuable metals from waste Li-ion batteries via solvent extraction and chemical precipitation

Abstract

Present work addresses Co(II) extraction from chloride medium using toluene diluted Cyphos IL 102 as an innovative extractant for the recovery of cobalt. Effect of various parameters has been examined. Co(II) is transferred into the organic phase as [P66614+]2[CoCl42−] which can be efficiently stripped by 0.05 mol L−1 HCl. Loading capacity and recyclability have been assessed. Temperature effect confirmed that the extraction of Co(II) is endothermic in nature. Studies were further extended to recover cobalt, manganese and lithium from waste Li-ion batteries containing 2.915 g L−1, 0.576 g L−1, 3.370 g L−1, 0.407 g L−1, 0.014 g L−1, 0.033 g L−1, 0.019 g L−1 of cobalt, lithium, manganese, nickel, aluminium, iron and copper, respectively. The influence of the concentration of Cyphos IL 102 to extract cobalt from leach liquor has been investigated. The McCabe-Thiele plot suggested two theoretical stages of counter current extraction at A/O 1/1 with Cyphos IL 102 (0.2 mol L−1) for the quantitative extraction of Co(II) with negligible extraction of nickel and lithium. A stripping efficiency of around 99.9% for Co(II) was obtained using 0.05 mol L−1 HCl in a single stage at O/A 1/1. Cobalt is recovered as cobalt oxide from the loaded organic phase. Manganese and lithium were also recovered from leach liquor as MnO2 and Li2CO3 using the precipitation method. All the recovered products were identified using XRD, EDX as well as FE-SEM techniques.