废旧磷酸铁锂电池正极材料酸浸液除杂及同步回收FePO_(4)研究

Simultaneous Removal of Impurities and Recovery of FePO_(4) from Acid Leaching Solution of Cathode Materials from Spent Lithium Iron Phosphate Batteries

以废旧磷酸铁锂电池正极材料酸浸液为原料,采用氧化-沉淀法回收铁、磷、锂元素。考察了沉淀过程中反应体系终点pH值、温度、氢氧化钠浓度、氢氧化钠滴加速度和过氧化氢与酸浸液的体积比对铁、磷沉淀率和锂损失率的影响。结果表明:反应体系终点pH值2.5、温度75℃、氢氧化钠浓度1.5 mol/L、氢氧化钠滴加速度7.7 mL/min、过氧化氢与酸浸液的体积比为1∶60条件下,铁平均沉淀率99.86%,磷平均沉淀率98.23%,锂平均损失率仅1.23%;在该条件下,铁和磷可以有效地从溶液中被去除,锂损失率较低;同时,铁、磷以磷酸铁形式回收利用,经700℃热处理5 h,所得磷酸铁元素组成符合行业标准。

The acid leaching solution of cathode materials from spent lithium iron phosphate batteries was taken as raw material,and iron,phosphorus and lithium elements therein were recovered by adopting an oxidation-precipitation process.The effects of factors,including endpoint pH value of reaction system,reaction temperature,concentration of sodium hydroxide,dripping rate of sodium hydroxide,and the volume ratio of hydrogen peroxide to acid leaching solution,on the precipitation rates of iron and phosphorus and the loss of lithium during the precipitation process were all investigated.Results show that with the endpoint pH value of 2.5,temperature of 75℃,sodium hydroxide with concentration of 1.5 mol/L,sodium hydroxide solution at a dripping rate of 7.7 mL/min,and hydrogen peroxide and acid leaching solution in a volume ratio of 1∶60,the average precipitation rates of iron and phosphorus are 99.86%and 98.23%,respectively,and the average loss of lithium is just 1.23%.Under the above-mentioned conditions,iron and phosphorus in the solution can be effectively removed and recycled in the form of iron phosphate,presenting a lower loss rate of lithium.After 5 h-heat treatment at 700℃,it is shown that the chemical composition of iron phosphate can meet the industrial standard.