TBP为萃取剂分离废磷酸铁锂电池中金属锂的研究

Separation of lithium metal from spent lithium iron phosphate batteries with TBP as extractant

LiFePO_(4)/C粉末盐酸浸出液中主要离子为Li^(+)、Fe^(3+)与少量的Cl^(-),符合TBP萃取Li^(+)必须存在过渡族金属离子与Cl^(-)的理论。探究了TBP萃取Li^(+)的机制以及氯离子供给剂、Fe^(3+)/Li^(+)摩尔比、Cl^(-)浓度与Li^(+)浓度对萃取的影响,得到Li^(+)最佳萃取分离条件。结果表明,以FeCl^(3+)AlCl_(3)为氯离子供给剂,模拟配制酸浸出液中Li^(+)是以[LiFeCl_(4)]·n TBP的络合形式被萃取;TBP萃取Li^(+)的最佳条件为:溶液中Fe^(3+)/Li^(+)摩尔比为1.5、Cl^(-)浓度为5 mol/L、Li^(+)质量浓度为1 g/L;当相比(O/A)为0.5时,在最佳条件下TBP对LiFePO_(4)/C粉末盐酸浸出液中Li^(+)的二级萃取率达到92%以上,以6 mol/L盐酸为反萃剂三级反萃后Li^(+)反萃率约为93%,反萃后有机相中Fe^(3+)等杂质质量分数低于1%。该方法使废旧磷酸铁锂电池中的锂分离率达到83%以上,实现废旧磷酸铁锂电池中金属锂资源再生的目的。

To recover lithium metal from cathode active material LiFePO_(4)/C powder in spent lithium iron phosphate batteries,main ions in the hydrochloric acid leaching solution of LiFePO_(4)/C powder are Li^(+),Fe^(3+)and a small amount of Cl^(-),which accords with the theoretical basis that there must be transition metal ions and Cl^(-)when TBP extracts Li^(+).The mechanism for TBP to extract Li^(+),and the influences of chloride iron supply agent,Fe^(3+)/Li^(+)molar ration,Clconcentration and Li^(+)concentration on extraction are explored,and the optimal extraction separation conditions for Li^(+)are obtained.Study results show that using Fe Cl^(3+)AlCl_(3)as chloride ion supplier,Li^(+)in the simulated acid leaching solution is extracted in the complex form of[LiFeCl_(4)]·n TBP.The optimal extraction conditions for TBP to extract Li^(+)are as follows:the molar ratio of Fe^(3+)/Li^(+)in the solution is 1.5,Cl^(-)concentration is 5 mol·L^(-1),the mass concentration of Li^(+)is1 g·L^(-1).When the ratio of organic phase and aqueous phase(O/A)is 0.5,under the optimal conditions,the secondary extraction rate of Li^(+)in LiFePO_(4)/C powder hydrochloride acid leaching solution by TBP exceeds 92%;Stripping rate of Li^(+)is around 93%after three-stage of stripping with 6 mol·L^(-1) hydrochloride acid as stripping agent,and the mass fraction of impurities such as Fe^(3+)in the organic phase is less than 1%after stripping.This method enables the separation rate of lithium from spent lithium iron phosphate battery to exceed 83%,achieving the regeneration of lithium resources in spent lithium iron phosphate batteries.