A closed-loop coupling process of leaching and solvent extraction for Li2CO3 and FePO4 recovery from spent LiFePO4

To satisfy the increasing global demand for the strategic metal lithium, recycling of LiFePO 4 (LFP) batteries has become an irresistible trend and poses a challenge due to the cost. A low-cost process of recovering Li and FePO 4 from simulated spent LFP was investigated through a closed-loop coupling technology of isomorphic substitution leaching and solvent extraction . A total of 99.41% of Li + can be leached, and 96% of FePO 4 can be recovered with an Fe 2 (SO 4 ) 3 :LFP molar ratio of 1:6, H 2 SO 4 :LFP molar ratio of 0.5:1, and 0.4 ml H 2 O 2 /g LFP for 30 min. An eleven-stage extraction process for Fe 3+ removal from lixivium-containing extraction, stripping and regeneration processes was designed and optimized. The total removal efficiency of Fe 3+ was 97.22% by the 40 vt% N235 + 15 vt% TBP + kerosene extraction system at a phase ratio O/A of 3.5/1, and the lithium concentration in raffinate was 10.074 g·L −1 . The closed-coupling process was carried out on the simulated spent LFP with a total Li recovery efficiency of >99%. The low-cost leaching agent Fe 2 (SO 4 ) 3 was cyclically utilized. The coupling process can not only serve as a promising efficient recycling method for spent LFP batteries but also supply an inspiring route for other expensive metal recycling.