Abstract:With the advent of large-scale decommissioning of lithium-ion batteries, the harm of waste batteries to the environment has gradually become prominent, and the utilization of valuable metals in spent batteries as "urban mines" has also received widespread attention. At present, the recovery process mainly focuses on lithium extraction, while the waste residue after lithium extraction does not concerned enough. Taking the iron phosphate extracted from spent lithium iron phosphate battery material as the research object, the direct acid leaching purification process was proposed, and the iron phosphate higher purity was obtained by changing the concentration of leaching solution, leaching time, and number of leaching times. The results show that the leaching rate of Al, Cu, Ca and Ni is 36%, 51.35%, 89.48% and 90.91%, respectively, under the conditions of ball milling, high temperature and high pressure, hydrothermal reaction, etc., indicating that acid leaching has an obvious removal effect on impurities in the recovery of iron phosphate from spent batteries. The experimental results provide the basis for the complete recycling process of lithium carbonate and iron phosphate from spent lithium iron phosphate materials to produce lithium iron phosphate.