砷滤饼的铜砷分离

Separation of copper and arsenic in arsenic filtration cake

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_2S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、Na_2S与砷滤饼质量比3:4、浸出时间4 h、温度80℃、H_2O_2 20 m L。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 Cu S in the residue and AsO_4^(3-) in the solution during the leaching process. The effects of various parameters, such as concentrations of Na Cl, mass ratio of Na_2S 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 Na Cl, liquid-solid ratio 7:1, mass ratio of Na_2S to arsenic filtration cake 3:4, leaching at 80 ℃ for 4h, with 20 m L H_2O_2. 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 FeSO_4 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.