采用浸出方法使砷滤饼中的铜砷元素进行分离,铜以硫化铜的形式沉淀,砷以砷酸根离子进入溶液中.考察NaCl浓度、Na 2 S添加量、液固比、时间及温度等因素对砷滤饼中砷、铜浸出率的影响.得出最优的工艺条件如下:NaCl溶液浓度为20g/L、液固比7:1、Na2S与砷滤饼质量比3:4、浸出时间4 h、温度80℃、H2O220 mL.在此最优工艺条件下,砷浸出率高达95.56%,铜浸出率低于0.5%,浸出渣铜含量富集至33.6%.浸出液采用硫酸亚铁沉砷方法,沉砷率可以达到98%,生成的砷酸铁晶体含砷量为32.15%,滤液含砷量为0.23g/L,滤液可以返回浸出过程,实现循环利用.
Leaching method was used to separate copper and arsenic in the arsenic filtration cake, which was achieved by the formation of CuS in the residue and AsO43-in the solution during the leaching process. The effects of various parameters, such as concentrations of NaCl, mass ratio of Na2S to arsenic filtration cake, liquid-solid ratio, leaching time and temperature, on leaching rate of As and Cu were investigated. On this basis, the optimal conditions are obtained through single factor experiment as follows, 20 g/L NaCl, liquid-solid ratio 7:1, mass ratio of Na2S to arsenic filtration cake 3:4, leaching at 80℃ for 4h, with 20 mL H2O2. Under this optimal condition, the leaching rate of As reaches 95.56%, and leaching rate of Cu is less than 0.5%. The copper content in leaching residue is as high as 33.6% (mass fraction). In addition, arsenic-containing leachate can be treated with FeSO4 and removal rate of As in leachate exceeds 98%. Arsenic content in the generated crystal is 32.15% (mass fraction), and arsenic concentration in the effluent is 0.23 g/L which can be returned to the leaching process.
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