Effective recycling of mixed spent lithium ion batteries using sodium persulfate, and saponified Cyanex 272

The presence of critical metals like lithium, manganese and cobalt is crucial in recycling spent lithium-ion batteries (SLIB). This study focuses on recovering these metals from SLIB powder through leaching, precipitation and solvent extraction. Key parameters affecting process efficiency were evaluated, along with the mechanism and kinetics of metal recovery. Optimal leaching rates of 96.8% lithium, 99.1% manganese, and 97.9% cobalt were achieved using 27% (v/v) HCl at 70°C and 10% (w/v) pulp density over 2 hours. Manganese was selectively precipitated with sodium persulphate at pH 1.3 for 4 hours. Lithium and cobalt were separated from the Mn-free solution using Na-Cyanex 272 at equilibrium pH 5.5, yielding a cobalt separation factor of 80.5. The McCabe-Thiele plot indicated two extraction stages with an aqueous-to-organic ratio of 1:1, achieving 99.6% cobalt extraction and 8% lithium co-extraction. Cobalt was back-extracted with 6% (v/v) HCl. The proposed process flow sheet offers a simple, effective method for metal recovery, supporting recycling businesses in extracting valuable resources efficiently.