废磷酸铁锂全组分资源化及杂质定向控制

Total component recycling and impurity directional control of waste lithium iron phosphate

为了实现废磷酸铁锂的全组分资源化,采用HCl、H_(2)O_(2)溶液作为浸取剂,LiOH·H_(2)O作为除杂剂,系统地研究废磷酸铁锂提锂过程中铁、磷、锂、铝、铜、镁元素的迁移规律。通过调控系统p H值实现对铝、铜、镁杂质元素的定向控制,得到较高纯度的Fe PO_(4)·xH_(2)O渣和氯化锂精制溶液。实验结果表明:H_(2)O_(2)及HCl试剂浓度分别为0.7和1.0 mol×L^(-1)、搅拌转速n为300 r×min^(-1)时,锂元素浸出率接近100%,但浸出液中铁、磷杂质的质量浓度ρB分别达到18.3、11.2 g×L^(-1);采用Li OH·H_(2)O将系统pH调控至1.1±0.05,可使质量分数为97.7%以上的铁、磷以FePO_(4)·x H_(2)O形式沉淀,其他元素保留在浸出液中;将浸出液p H值调至7.0~8.0即可将铝、铜元素排出系统;再将溶液pH值调至11.0~11.5,可将镁元素以Mg(OH)_(2)的形式去除,最后采用盐酸将pH值调回中性,即可得到氯化锂精制溶液,锂的回收率为97.3%。

In order to realize the full component recycling of waste Li Fe PO_(4),the migration law of iron,phosphorus,lithium,aluminum,copper and magnesium in lithium extraction from waste Li Fe PO_(4) was systematically studied using HCl and H_(2)O_(2) as leaching agents and Li OH·H_(2)O as an impurity removal agent.Directional control of Al,Cu and Mg impurities was realized by adjusting system p H values,and high purity Fe PO_(4)·x H_(2)O slag and lithium chloride refining solution were obtained.The experimental results show that when the concentrations of H_(2)O_(2) and HCl are 0.7 and 1.0 mol×L^(-1) respectively,and the stirring speed n is 300 r×min^(-1)lithium leaching rate is close to 100%while the contents of iron and phosphorus impurities in the leaching solution are 18.3 and 11.2 g×L^(-1),respectively.More than 97.7%of iron and phosphorus precipitated as Fe PO_(4)·xH_(2)O when using Li OH·H_(2)O to adjust the system p H to 1.1±0.05,and other elements remained in the leaching solution.Aluminum and copper can be discharged from the system by adjusting the p H value of the leaching solution to 7.0-8.0.When the p H value of the solution was adjusted to 11.0-11.5,magnesium can be removed in the form of Mg(OH)_(2).Finally,the p H value was adjusted back to neutral with hydrochloric acid to obtain a refined solution of lithium chloride with lithium recovery of 97.3%.