电化学沉淀法净化含氰废水研究

Study on the cyanide-bearing wastewaters purification by electrochemical precipitation method

含氰废水绿色、低成本处理制约着黄金氰化企业的可持续发展。以锌板为牺牲阳极,采用电化学沉淀法处理含氰废水,考察了电流密度、pH和初始总氰化合物浓度对氰化物去除效果的影响。结合循环伏安法、pH_(pzc)、X射线衍射法、扫描电镜/能谱法和X射线光电子能谱法表征结果阐释氰化物去除机理。试验结果表明:在最佳条件下,工业含氰废水中总氰化合物、铜和铁去除率分别达到98%、91%和96%。游离氰化物主要以Zn(CN)_(2)形式进入电解沉淀渣中;Zn^(2+)发生置换和电化学还原,使得含氰废水中72%铜在阴极得到回收;铁主要形成Zn_(2)[Fe(CN)_(6)]进入电解沉淀渣中。

Green and cost-effective treatment of cyanide-bearing wastewaters(CBWs)restricts sustainable development of gold cyanidation plants.Electrochemical precipitation method is used to treat CBWs with Zn plate as galvanic anode.The effects of current density,pH,and initial total cyanide concentration on cyanide removal performance were discussed.Then,the removal mechanisms of cyanide were elucidated by a combination of cyclic voltammetry,pH_(PZC),XRD,SEM-EDS and XPS characterization.The experimental result demonstrated that the removal rates of total cyanide,Cu and Fe in industrial CBWs are respectively 98%,91%and 96%under optimal conditions.Removal mechanisms suggested that free cyanide,mainly in the form of Zn(CN)_(2),goes into the electrolytic residue.The effect of Zn^(2+) replacement and electro-reduction promoted 72%of Cu from CBWs to be reduced and recovered in the cathode.Fe,mainly in the form of Zn_(2)[Fe(CN)_(6)]precipitate,goes into the residue.