Study on metal recovery process and kinetics of oxidative leaching from spent LiFePO4 Li-batteries

A green environmental protection and enhanced leaching process was proposed to recover all elements from spent lithium iron phosphate (LiFePO 4 ) lithium batteries. In order to reduce the influence of Al impurity in the recovery process, NaOH was used to remove impurity. After impurity removal, the spent LiFePO 4 cathode material was used as raw material under the H 2 SO 4 system, and the pressure oxidation leaching process was adopted to achieve the preferential leaching of lithium. The E-pH diagram of the Fe-P-Al-H 2 O system can determine the stable region of each element in the recovery process of spent LiFePO 4 Li-batteries. Under the optimal conditions (500 r·min –1 , 15 h, 363.15 K, 0.4 MPa, the liquid-solid ratio was 4:1 ml·g –1 and the acid-material ratio was 0.29), the leaching rate of Li was 99.24%, Fe, Al and Ti were 0.10%, 2.07% and 0.03%, respectively. The Fe and P were precipitated and recovered as FePO 4 ∙2H 2 O. The kinetic analysis shows that the process of high-pressure acid leaching of spent LiFePO 4 materials depends on the surface chemical reaction. Through the life cycle assessment (LCA) of the spent LiFePO 4 whole recovery process, eight midpoint impact categories were selected to assess the impact of recovery process. The results can provide basic environmental information on production process for recycling industry.