退役磷酸铁锂正极材料提锂渣资源化回收工艺

Resource Recycling Technology of Lithium Extraction Residue of Spent Lithium Iron Phosphate Anode Material

目前退役磷酸铁锂正极材料的回收主要是通过选择性浸出回收锂,已实现工业化运行。然而,退役磷酸铁锂正极材料中锂回收后残留的磷铁渣尚未出现有效的处理方法,亟待解决。提出一种盐协助碳热还原—水浸分离法,先通过K_(2)CO_(3)和碳热还原共同作用将FePO_(4)转化为Fe和磷钾化合物,再通过水浸方式将铁和磷分离。系统研究了碳热还原条件对铁磷分离效果的影响。结果表明,在焙烧温度900℃、焙烧保温时间4.0 h、K_(2)CO_(3)与磷铁渣质量比0.7、碳粉与磷铁渣质量比0.3的条件下,焙烧产物经常温水浸分离,Fe的回收率为99.3%,水浸固体产物经磁选分离可得到Fe含量为95.2%的产物,实现了磷铁渣中铁与磷的高效分离。本工艺具有不使用强酸、回收过程简单、磷铁渣利用率高等优点,具有工业应用潜力。

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.FePO 4 was converted to Fe and potassium phosphate compound through the combined reaction of K_(2)CO_(3) 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 ofroasting temperature of 900℃,roasting holding time of 4.0 h,mass ratio of K_(2)CO_(3) 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.