Abstract:At present, the recovery of spent lithium iron phosphate cathode materials is mainly through selective leaching to recover lithium, which has achieved industrial operation. However, there is no effective method for handling the phosphorus iron residual after lithium recovery from retired lithium iron phosphate cathode materials, which needs to be solved urgently. A salt-assisted carbon thermal reduction and water leaching separation method was put forward. FePO4 was converted to Fe and potassium phosphate compound through the combined reaction of K2CO3 and carbon thermal reduction, and then iron and phosphorus were separated by water leaching. The effects of carbon thermal reduction conditions on separation of iron and phosphorus were systematically studied. The results show that under the conditions of roasting temperature of 900 ℃, roasting holding time of 4.0 h, mass ratio of K2CO3 to phosphorus iron slag of 0.7, and mass ratio of carbon powder to phosphorus iron slag of 0.3, the recovery rate of Fe is 99.3%, and the solid product obtained from water leaching could be separated by magnetic separation to obtain a product with Fe content of 95.2%. The efficient separation of iron and phosphorus in phosphorus iron slag is achieved. The process has the advantages of no use of strong acid, simple recovery process, high utilization rate of phosphorus iron slag, and has the potential of industrial application.