P507+N235高酸砷铁反萃溶液处理工艺的优化

Treatment Process Optimization of P507+N235 High-acid Iron and Arsenic Stripping Solution

介绍了某锌冶炼厂采用P507+N235组成的双溶剂萃取体系从硫酸浸出液中萃取砷铁的生产情况,并对高酸砷铁反萃溶液返回锌冶炼系统存在的问题进行分析。采用膜分离工艺处理反萃溶液,对比分析纳滤膜和扩散渗析膜分离的工艺条件和投资运行成本。结果表明,纳滤膜和扩散渗析膜均可以有效分离溶液中杂质元素:其中采用纳滤膜工艺时,截留浓液中铁、砷、锌、硫酸和油份的截留率分别为91.2%、88.55%、87.5%、47.44%和50%,酸回收利用率为52.56%;采用扩散渗析膜工艺,渗析残液中铁、砷、锌、硫酸和油份的截留率分别92%、87.94%、90%、5.13%和75%,酸回收利用率为94.87%。截留浓液和渗析残液均采用石灰中和法脱除溶液中的砷铁,过滤溶液返回系统实现资源循环利用,扩散渗析膜相比纳滤膜投资少,操作维护简单,生产成本低,更适合用于工业生产。

The production situation of extracting arsenic and iron from sulfuric acid leaching solution by double-solvent extraction composed of P507+N235 in a zinc smelter was introduced,and the problems existing in returning high-acid arsenic and iron solution obtained by stripping to zinc smelting system were analyzed.Membrane separation process was used to treat stripping solution.The technological conditions and investment and operation costs of nanofiltration membrane and diffusion dialysis membrane were compared and analyzed.The results show that both nanofiltration membrane and diffusion dialysis membrane can effectively separate impurity elements in the solution.In the membrane process,the retention rate of Fe,As,Zn,H_(2)SO_(4) and oil in retained concentrate is 91.2%,88.55%,87.5%,47.44% and 50%,respectively,and acid recovery rate is 52.56%;in diffusion dialysis membrane process,the retention rate of Fe,As,Zn,H_(2)SO_(4) and oil in dialysis residue is 92%,87.94%,90%,5.13% and 75%,respectively,and the acid recovery rate is 94.87%.Both the retained concentrate and the dialysis residue are treated by lime neutralization method to remove arsenic and iron in the solution,and the filtration solution is returned to the system to realize resource recycling.Compared with nanofiltration membrane method,diffusion dialysis membrane method has low investment,simple operation and maintenance,low production cost,and is more suitable for industrial production.