锌粉单耗高和净化除镉渣中镉含量低是硫酸锌溶液锌粉置换除镉存在的共性难题，其核心原因是锌粉被产物层包裹降低其反应活性。基于此提出了机械活化强化硫酸锌溶液两级锌粉逆流置换除镉新方法，一级添加较低系数的锌粉产出高镉品位的净化渣，二级添加较高系数的锌粉，以控制硫酸锌溶液中镉达到溶液净化质量要求。研究结果表明，在总锌粉添加系数为1.02、反应温度60℃、反应时间60min的条件下，其中当一级锌粉添加系数为0.9，二级锌粉添加系数为1.2时，一级净化后液中镉浓度由反应前的1530mg/L降低至60~70 mg/L，一级净化产出的镉渣中镉含量富集至81.54%，锌含量小于10%；二级净化后液中镉浓度降低至2~5 mg/L，净化渣中的镉含量为16%，锌含量为55%。一级净化渣主要物相为单质镉，二级净化渣的主要物相是未反应的锌和部分单质镉。与传统一次净化工艺相比，通过流体的剪应力和机械活化作用，破坏了锌粉表面的包裹层，消除了锌粉表面的包裹现象，提高了锌粉利用效率，降低了锌粉消耗，提高了净化渣中的镉含量。

High single consumption of zinc powder and low cadmium content in purified cadmium removal residue are common problems in zinc sulfate solution zinc powder replacement for cadmium removal, and the core reason is that zinc powder is wrapped by the product layer to reduce its reactivity.Based on this, a new method for countercurrent replacement of two-stage zinc powder in enhanced zinc sulfate solution by mechanical activation was proposed, and zinc powder with a lower coefficient was added to produce advanced cadmium in the first stage, and zinc powder with a higher coefficient was added in the second stage to control the cadmium content in zinc sulfate solution to meet the quality requirements of solution purification. The results show that under the conditions of total zinc powder addition coefficient of 1.02, reaction temperature of 60°C and reaction time of 60min, when the addition coefficient of primary zinc powder is 0.9 and the addition coefficient of secondary zinc powder is 1.2, the concentration of cadmium in the liquid after primary purification is reduced from 1530mg/L before reaction to 60~70 mg/L, and the cadmium content in the cadmium residue produced by primary purification is enriched to 81.54%, and the zinc content is less than 10%. After secondary purification, the concentration of cadmium in the solution was reduced to 2~5 mg/L, and the cadmium content in the purification residue was 16%, and the zinc content was 55%. The main phase of the primary purification residue is elemental cadmium, and the main phase of the secondary purification residue is unreacted zinc and some elemental cadmium. Compared with the traditional primary purification process, through the shear stress and mechanical activation of the fluid, the wrapping layer on the surface of the zinc powder is destroyed, the wrapping phenomenon on the surface of the zinc powder is eliminated, the utilization efficiency of zinc powder is improved, the consumption of zinc powder is reduced, and the cadmium content in the purification residue is improved.

TF819.2

国家自然科学基金(52164039);云南省科技厅重大科技专项计划项目(202202AG050025)；云南省应用基础研究计划项目(202001AT070079)