次氧化锌酸性浸出液中萃取分离铟的工艺

Solvent extraction and separation of indium from leaching solution of zinc oxide

以次氧化锌酸性浸出液为原料,采用两段溶剂萃取的方法实现铟与其他金属离子的有效分离,并循环利用工艺过程中使用的盐酸,减少氯离子的排放。研究采用P204从浸出液中萃取、盐酸反萃铟的行为,以及采用TBP/P350混合萃取剂从P204载铟有机相盐酸反萃液中选择性萃取铟、水反萃等过程中铟的行为,考察萃取剂浓度、混合时间、酸浓度和相比等因素对铟萃取率和反萃率的影响。结果表明:采用10%P204(体积分数)在相比(A/O)为2/1的条件下,经过2级逆流萃取,浸出液中99%铟被萃取,得到的P204载铟有机相采用6 mol/L盐酸反萃,铟反萃率达100%。得到的含铟盐酸反萃液再采用TBP/P350选择性萃取铟,在相比为3/2条件下,经过2级逆流萃取,铟萃取率为99%,得到的载铟有机相采用纯净水进行3级逆流反萃,铟被反萃完全。与传统工艺相比,氯离子排放量减少86%。基于上述实验结果,提出从次氧化锌酸性浸出液中萃取分离铟的工艺流程,在实现铟高效回收的同时,降低氯离子的排放,达到资源高效利用和减少污染物排放的目的。

The two stages solvent extraction of indium from the zinc oxide leaching solution was studied to separate indium, recycle used wasted HCl and reduce the chloride ion discharge. The extraction and stripping of indium with P204 and TBP/P350 were studied under different parameters, such as the concentration of extractant, contact time, acidity and ratio of aqueous and organic phase. The results indicate that 99% indium is extracted by 10% P204（volume fraction） with two stages at A/O ratio of 2/1. Indium in the P204 loaded organic is effectively stripped by 6 mol/L HCl. The 99% of indium in the P204 loaded organic stripping solution is selective extracted by TBP/P350 with two countercurrent extraction stages at A/O ratio of 3/2. Then, indium in the TBP/P350 loaded organic is stripped by water with three countercurrent stripping stages. Comparing to traditional processes, more than 86% of chloride ion is reduced. Based on this study, a new flow sheet for extraction of indium from the zinc oxide leaching solution was presented, which achieves the purpose of efficient utilization of indium resources as well as reducing chloride pollution emission. By this process, more than 98% of indium is efficiently extracted, at the same time, over 86% of chloride ion is reduced.