基于田口方法的分银渣浸铅工艺优化研究

Optimization of Leaching of Lead from Silver Separated Residue Based on Taguchi Method

采用氯盐浸出-提纯-结晶-制备黄丹工艺处理分银渣,基于田口方法确定氯盐浸出铅的优化条件,得到工艺参数中影响铅浸出率的主次顺序为:NaCl用量>液固比>温度>CaCl2用量/理论量。NaCl用量对铅浸出率的贡献率最大,贡献率达到61.82%,是分银渣浸铅过程最重要的工艺参数;液固比为较重要因素,贡献率为31.27%;温度和CaCl2用量/理论量对铅浸出率的贡献率分别为4.95%和1.96%。从分银渣中浸出铅的最优条件为:NaCl用量350 g/L、CaCl2用量/理论量0.5、温度90℃、液固比10∶1,在优化条件下进行3次验证性实验,铅浸出率分别为94.89%、94.75%和95.11%,数值分布稳定,浸出率较高。采用该工艺制备的黄丹纯度为99.12%,产品达到GB 3677—83二级品质量标准。

The silver separated residue(SSR) was treated by adopting a process of chloride leaching and purification, followed by crystallization and huangdan preparation. The optimal conditions for lead leaching with chloride was determined based on Taguchi method and the process parameters influencing the lead leaching rate is listed in the following descending order: NaCl dosage > liquid-solid ratio > temperature > dosage/theoretical amount of CaCl2. It is found that the amount of NaCl plays the biggest role in the lead leaching efficiency, with a contribution rate up to 61.82%, which is the most important process parameter for the lead leaching process of the SSR;the liquid-solid ratio is a more important factor, with a contribution rate of 31.27%;temperature and dosage/theoretical amount of CaCl2 have respectively contributed 4.95% and 1.96% to the lead leaching rate. The optimal conditions for leaching lead from the SSR have been determined. Three verification experiments with the dosage of NaCl at 350 g/L, the amount or theoretical amount of CaCl2 of 0.5, the temperature of 90 ℃ and the liquid-to-solid ratio of 10∶1 resulted in the lead leaching rates up to 94.89%, 94.75% and 95.11%, respectively, showing stable numerical distribution and high leaching rate. The purity of Huang Dan prepared by this technique is up to 99.12%, and the products meet the secondary quality standard of GB 3677—83.