亚硫酸钠浸出-甲醛还原回收氯化渣中的银

为了改善氰化金泥湿法精炼过程中氯化渣铁粉置换工艺熔炼粗银时的工作环境,提高银的回收率,采用亚硫酸钠浸出-甲醛还原方法处理氯化渣。结果表明,在pH=8.5、液固质量比为20:1、35℃的条件下用浓度为250g/L的亚硫酸钠溶液浸出氯化渣3h后,银浸出率大于99%;浸银液在40%甲醛与银比例为5:2 (mL/g)、50℃的条件下还原1.5 h,银还原率达99%以上。浸出渣返回金泥氯化分金流程,浸银液还原后可再生循环使用,银综合回收率可达98%以上。

Recovery of Silver in Chloride Residue by Sodium Sulfite Leaching-Formaldehyde Reduction Process

In order to improve the working environment of smelting coarse silver by the replacement process of iron powder from chloride residue in the wet refining process of cyanide gold mud and the recovery of silver,selective leaching of silver from chlorinated residue and silver reduction with formaldehyde have been investigated.The results showed that the silver leaching ratio of chlorinated residue was over 99%after leaching by 250 g/L sodium sulfite solution with a liquid-solid mass ratio(L/S)of 20:1 for 3 hours at pH 8.5 and 35℃.The leached solution was reduced by formaldehyde with a ratio of 40%formaldehyde to silver of 5:2(mL/g)for 1.5 h at 50℃,and the silver reduction rate was over 99%.The leached residue was returned to the gold slime chlorination process,and the silver leaching solution could bereuseble,and the comprehensive recovery rateof silver could reach over 98%.