Abstract:A sustainable approach for recovering battery grade FePO₄ and Li₂CO₃ from Al/F-bearing spent LiFePO₄/C powder was proposed, including acid leaching, fluorinated coordination precipitation, homogeneous precipitation, and high-temperature precipitation. Under the optimal conditions, the leaching efficiencies of Li, Fe, P, Al, and F were 97.6%, 97.1%, 97.1%, 72.5%, and 63.3%, respectively. The effects of different parameters on the removal of Al/F impurities were systematically evaluated, indicating about 99.4% Al and 96.4% F in the leachate were precipitated in the form of Na₃Li₃Al₂F₁₂, and their residual concentrations were only 0.0124 and 0.328 g/L, respectively, which could be directly used to prepare battery grade FePO₄ (99.68% in purity). Lithium in the Al/F-bearing residue could be extracted through CaCO₃-CaSO₄ roasting followed by acid leaching, ultimately obtaining 99.87% purity of Li₂CO₃. The recovery rates of Li and Fe were 96.88% and 92.85%, respectively. An economic evaluation demonstrated that the process was profitable.

Key words: Al/F-bearing spent LiFePO₄/C powder; sulfuric acid leaching; impurities removal; battery grade iron phosphate; battery grade lithium carbonate