铜冶炼高砷烟尘浸出特性研究

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。

On the leachability of high arsenic smoke-dust from the copper smelting processing

This paper is aimed to present its investigation results of the high arsenic dust originated from the metallurgical production in which copper is smelted with large amounts of arsenic duct of 15.06％ in major arsenic components of Pb2As2O7 and(Fe,Zn)3 (AsO4)2 · 8H2O.Through water leaching,it can separate and synthetically determine the impacts of the leaching temperature(T) and leaching time(t),the ratio of liquid-to-solid(L/S),the pH value of the leaching solution on the As,Pb,Zn components in the high arsenic dust.Besides,it is also possible to characterize the microstructure of the raw material and leaching residue through X-ray diffraction (XRD) and the electronic microscopy(SEM) to identify and demonstrate the dissolved mechanism of the high arsenic dust.And,all in all,the final leaching results can help to confirm the aforementioned liquid-to-solid ratio (L/S) and the effect of the pH value of the leaching solution on the leaching efficiency of the above said products.What is more,the leaching temperature and time also have some significance on the leaching efficiencies of the said high arsenic dust.In a more detailed way,the optimal leaching conditions can be illustrated as follows:leaching temperature:50 ℃;leaching time length:30 min;the ratio of liquid to high arsenic dust:10 ∶ 1;the pH value of the solution to be leached:1.0 at the stirring speed of 300 r/min.Under the above stated conditions,it would be possible for the leaching efficiency of Pb,As and Zn to reach by 0.5％ (less),93％ and 95％,respectively.The results of XRD and SEM show that the arsenic speciation of Pb2As2O7 in the high arsenic dust can be dissolved into ions of Pb2 + and AsO43-under the strong acidic conditions.Furtherly speaking,since Pb2+ and AsO43-ions gained can be used to promote the composition of the sparingly soluble PbSO4 compounds,they can also be used to reduce the Pb leaching efficiencies of the copper smelting dust.Therefore,the arsenic phase of(Fe,Zn)3 (AsO4)2 · 8H2O can be said in a position to dissolve Zn2+ and AsO43-ions to further heighten the Zn and Pb leaching efficiencies of copper smelting dust.