Abstract:In spent lithium iron phosphate batteries, lithium has a considerable recovery value. Inorganic salt Fe2(SO4)3 and Fe2(SO4)3-H2O2 were used as the leaching agent to extract lithium from lithium iron phosphate positive powder. The effects of the type of leaching agent, reaction time, temperature, ratio of liquid-solid (L/S), Fe2(SO4)3 dosage and type of oxidant on the selective lithium extraction process were investigated. The results show that 91.19% of lithium and only 0.02% of P were leached out under the optimal conditions including L/S=5 mL/g, Fe2(SO4)3 dosage of 1.5 times of raw material, reaction temperature of 20 ℃, and reaction time of 20 min. The leaching rate of Li is 99.09% and leaching rate of P is 0 under the conditions including L/S=5 mL/g, temperature of 20 ℃, Fe2(SO4)3 dosage of 0.6 time of raw material, reaction time of 20 min, and pH value of 4.1—4.6 adjusted with H2O2, which the selective leaching effect of Li is excellent. The leaching system of Fe2(SO4)3-H2O2 saves 60% of the amount of Fe2(SO4)3, and the leaching agent is easily utilized by recycling ring. The obtained ferric phosphate slag is pure and the molar ratio of Fe/P is 0.976, which can be used to prepare new LFP cathode materials.