硫酸锌溶液锌粉逆流置换除镉及直接制备海绵镉

Removal of Cadmium from Zinc Sulfate Solution by Zinc Powder Countercurrent Cementation and Directly Produce Cadmium Sponge

针对硫酸锌溶液采用锌粉置换净化除镉时造成大量锌粉浪费、除镉产物含镉低、后续处理复杂等难题,提出碱度控制与三级逆流锌粉置换新方法,解决产物层包裹和锌粉利用率低的问题,以期能够降低锌粉耗量,缩短镉回收流程,直接制备出海绵镉。考察了锌粉用量、锌粉粒度、净化时间、锌粉添加方式、碱度(BT)值调控等参数对镉脱除率的影响。结果表明:单段除镉的优化条件为温度60℃、搅拌速度150r/min、锌粉浆化预处理、锌粉用量为理论添加量的1.2倍、反应时间120min;通过三级逆流锌粉净化除镉,镉的浓度由2.29g/L降低至0.48mg/L,镉的脱除率超过99.9%,可实现硫酸锌溶液中镉的深度净化;净化过程可直接产出镉含量为80.5%的海绵镉。研究结果对湿法炼锌净化过程降低锌粉消耗、缩短镉回收流程具有指导意义。

In view of the problems both including large amount of zinc powder waste,low cadmium content in the cadmium removal products and complex subsequent treatment caused by zinc powder replacement purification of zinc sulfate solution,a new method of alkalinity control and three-level countercurrent zinc powder replacement was proposed to solve the problems of product layer wrapping and low utilization of zinc powder,so as to reduce the consumption of zinc powder,shorten the cadmium recovery process and directly prepare cadmium sponge.The effects of zinc powder dosage,zinc powder particle size,purification time,zinc powder addition method,BT value control and other parameters on cadmium removal rate were investigated.The results show that the optimum conditions for single-stage cadmium removal are temperature 60℃,stirring speed 150r/min,zinc powder slurry pretreatment,zinc powder dosage 1.2times the theoretical addition,and reaction time 120min.The concentration of cadmium is reduced from 2.29g/L to 0.48mg/L by three-stage countercurrent zinc powder purification,and the removal rate of cadmium is above 99.9%,which can realize the deep purification of cadmium in zinc sulfate solution.The purification process can directly produce cadmium sponge with cadmium content of 80.5%.The research results have guiding significance for reducing zinc powder consumption and shortening cadmium recovery process in zinc hydrometallurgy purification process.