(中南大学 冶金与环境学院，长沙 410083)
摘 要: 提出一种基于微电流作用下的提镉新工艺，采取正交试验考察各工艺参数对海绵镉提取过程的影响，并对ZnSO4+CdSO4混合溶液中Zn2+、Cd2+的阴极行为进行电化学研究。结果表明：各因素对提镉率的影响由大到小的顺序依次为温度、pH、极距、电流密度、阴阳极面积比；最佳工艺条件为pH=1、极距3 cm、电流密度400 A/m2、温度90 ℃、阴阳极面积比1:2，在此条件下电置换1 h提镉率达到79.31%；镉先于锌在阴极析出，当锌开始析出时，溶液中镉离子浓度已降到很低，最低可降至0.528 mg/L。混合溶液阴极沉积的表观活化能为6.379 kJ/mol，在60~90 ℃时属于扩散步骤控制。
关键字: 镉；微电流；锌板置换；电化学
（School of Metallurgy and Environment, Central South University, Changsha 410083, China）
Abstract:A new process of cadmium extraction under micro-current was proposed. In order to determine the optimum process parameters, five main effect factors were investigated by an orthogonal experiment. Electrochemical experiments of the cathodic behavior of Zn2+, Cd2+ in mixed solution of CdSO4+ZnSO4 were conducted. The results show that the influence factors on extraction rate decrease in such an order: temperature, pH, polar plate distance, current density, plate area ratio. The optimal conditions are obtained at pH of 1, polar plate distance of 3 cm, current density of 400 A/m2, temperature of 90 ℃ and plate area ratio of 1:2. The maximum extraction rate is 79.31%. Cadmium is prior to precipitate than zinc. The concentration of Cd2+ in solution decreases to the minimum of 0.528 mg/L while zinc begins to deposit. The apparent activation energy of deposition is 6.379 kJ/mol. The diffusion-controlled is the dominant process at temperature ranging in 60-90 ℃.
Key words: cadmium; micro-current; zinc plate cementation; electrochemistry
