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以水为浸取剂,浸出铜冶炼过程中产生的高砷烟尘(砷质量分数为15.06%),研究了反应温度(T)、反应时间(t)、液固比(L/S)、pH值等因素对As、Pb、Zn浸出率的影响,并采用X射线衍射(XRD)和扫描电子显微镜(SEM)等表征方法分析了原料及浸出渣的微观结构,揭示了高砷烟尘中As、Pb、Zn物相的溶解机理。结果表明,以Pb_2As_2O_7和(Fe,Zn)_3(AsO_4)_2·8H_2O存在形态为主的高砷烟尘浸出特性受液固比、pH值的影响十分显著,而受反应温度、反应时间的影响很小。在T=50℃、t=30 min、L/S质量比=10∶1、pH=1.0、搅拌速度300 r/min的条件下,Pb浸出率小于0.5%,As浸出率为93%,Zn浸出率为95%。XRD和SEM结果表明,在强酸性条件下,烟尘中的Pb_2As_2O_7物相可溶解释放Pb~(2+)和AsO_4~(3-),而生成的Pb~(2+)可与液相SO_4~(2-)反应生成PbSO_4沉淀,进而降低Pb的浸出率;(Fe,Zn)_3(AsO_4)_2·8H_2O溶解释放出Zn~(2+)和AsO_4~(3-),可进一步提高As和Zn的浸出率。
(Arsenic content 15.06%) was produced by leaching copper smelting process with water as leaching agent. The effects of reaction temperature (T), reaction time (t), liquid / solid ratio (L / S) Pb and Zn on the leaching rate of As, Pb and Zn. The microstructure of raw materials and leached residue were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) Dissolution mechanism of Pb and Zn phases. The results show that the leaching characteristics of high-arsenic fume and dust with Pb 2 As 2 O 7 and (Fe, Zn) 3 (AsO 4) 2 · 8H 2 O as main forms are affected by the ratio of liquid to solid and pH value very much, but influenced by reaction temperature and reaction time small. Under the conditions of T = 50 ℃, t = 30 min, L / S mass ratio = 10:1, pH = 1.0 and stirring speed 300 r / min, the leaching rate of Pb was less than 0.5% Leaching rate of 95%. The results of XRD and SEM show that Pb 2+ and AsO 4 3- can be released by Pb 2 As 2 O 7 in soot under strong acid conditions, (2) reaction leads to the precipitation of PbSO 4, which in turn reduces the leaching rate of Pb. The dissolution of (Fe, Zn) _3 (AsO_4) _2 · 8H_2O can release Zn 2+ and AsO 4 3-, The leaching rate of Zn.