锌冶炼含镉烟尘制备高纯镉粉的新工艺

New technology of high purity Cd powder prepared from roasting dust of zinc smelting

采用硫酸浸出锌冶炼含镉烟尘，得到含镉硫酸浸出液，在硫酸镉浸出液中加入双氧水和 FeCl3溶液，用NaOH溶液调节pH值后过滤，将滤液加入NaOH溶液中得到Cd（OH）2粉体，采用氢气还原得到镉粉。结果表明：当硫酸浓度为110 g/L、反应温度为65℃时，镉浸出率达99.63%。双氧水用量为理论量10倍、n（Fe）/n（As）为3：1、pH=5.5时，砷的去除率达99.5%，得到净化的硫酸镉溶液。将硫酸镉溶液以缓慢加料方式加入浓度为2 mol/L的NaOH溶液中，反应温度为25℃，控制终点pH=10，过滤洗涤得到粒径为10~20μm的Cd（OH）2粉体，采用氢气还原Cd（OH）2粉体，在反应温度为310℃、反应时间120 min、氢气流量40 L/h时，得到平均粒径为49.61μm的球形镉粉。

The CdSO4 solution was prepared by leaching roasting dust of zinc smelting with sulfuric acid, then, the CdSO4 solution was purified by adding hydrogen peroxide and ferric chloride and adjusting pH with sodium hydroxide. Cd（OH）2 powder was prepared after the purified CdSO4 solution mixed with NaOH solution, then, reduced with hydrogen. The results show that the leaching rate of Cd reaches 99.63% under the condition of H2SO4 concentration of 110 g/L, reaction temperature of 65℃. Under the condition thatn（Fe）/n（As） is 3：1 and pH is 5.5, the removal rate of As can be higher than 99.5%. The obtained Cd（OH）2 particle size is 10-20 μm when the reaction temperatureis 25℃, pH value of the solution is 10. High purified Cd powders were prepared from Cd（OH）2 particles reduced by hydrogen. The optimum process conditions are as follows： reaction temperature is 310℃, reaction time is 120 min and hydrogen flow is 40L/h. The average particles size of spherical Cd powder is about 49.61 μm.