含砷铜烟尘砷的选择性分离实验

Selective Separation Experiments of As from Copper Dust Containing As

在氮气气氛下,采用低温焙烧的方法对含砷铜烟尘中的砷进行选择性分离,研究了温度、氮气流量和焙烧时间的变化对砷挥发率的影响,用X射线衍射分析、差热-差重分析等方法研究了含砷铜烟尘中砷的挥发规律,并分析了砷挥发过程的动力学。结果表明,含砷铜烟尘中砷的选择性分离应在低温下进行,避免高温下Zn、Pb挥发损失和As_2O_3生成难挥发的砷酸盐。在250℃,氮气流量300mL/min、焙烧120min的条件下,砷的挥发率为95.68%,渣中砷的含量为0.79%,其他有价金属基本不挥发,实现了砷与其他有价金属的选择性分离,砷以初级As_2O_3产品回收,纯度为96.85%。动力学研究表明,在一定范围内,砷的低温选择性挥发过程符合收缩核模型,其表观活化能为19.71kJ/mol,该过程受内扩散控制。

In order to separate As from As-contained dust,the dust was treated by roasting at low temperature under nitrogen atmosphere.The influence of temperature,nitrogen flow rate and roasting time on the evaporation rate of As were discussed in this paper.The methods such as XRD analysis and thermogravimetric analysis were employed to study the evaporation process of As.The kinetics of As evaporation was also investigated.It was demonstrated that selective separation of As should be taken at low temperature in order to avoid evaporation loss of Zn,Pb at high temperature and producing arsenates which are hard to volatile.The evaporation rate of As was 95.68%,the content of arsenic in the slag was 0.79%,and other valuable metals were not volatile under the conditions of roasting temperature of 250℃,nitrogen flow rate of 300 mL/min and roasting time of 120 min.As was selectively separated from other valuable metals and was recovered in the form of As 2O 3 with a purity of 96.85%.It was demonstrated by kine-tic study that the selective separation process of As at low temperature was in accordance with the shrinking ore model in a certain range.The apparent activation energy was 19.71 kJ/mol and As evaporation process was controlled by internal diffusion.