金矿氰渣氯化挥发烟气回收工艺的技术研究

Study on the recovery process of cyanide residue in gold mine

低品位的金矿氰渣经过氯化挥发系统产生高温烟气冷凝后形成高金的酸性金泥,加入保护碱调节pH之后,一般直接进入氰化浸出回收金,氰化法回收金泥中的金存在着回收率偏低、药剂消耗大、金柜滤布堵塞等一系列问题。本文采用氯化法浸出金泥,即在盐酸介质中加入氯化钠作氧化剂,并研究了盐酸浓度、氯酸钠浓度、浸出温度、浸出时间对金浸出率的影响。经氯化浸出、浸出液铁粉置换、尾渣二次氯化挥发工序可以有效回收了金泥中的金。在液固比为2︰1,盐酸浓度为15%,氯酸钠用量为60 kg/t,浸出温度为20℃,浸出时间为4 h时,金的浸出率达到92%以上,与之对比的氰化平均浸出率为89.37%,与氰化法相比浸出率提高了3%~5%,浸出时间由24 h缩短为4 h;铁粉置换氯化浸出液中金、铜的置换率分别达到99%以上。

Metal elements of low grade cyanide tailings can form a high temperature gas-phase metal chloride from by chlorination roasting. The metal chloride then condensed to form a high-grade gold-beating acidic material which is also called gold mud. After ad- justing the pH by alkaline substance, gold can be extracted from the alkaline gold-bearing material by cyanidation. However, several problems also existed in the process of recovery of gold from gold mud by cyanidation such as the comparatively low gold extraction rate, the consumption of reagent, the blocking of filter cloth. In this paper, leaching of gold with the chlorination method was studied. The effect of hydrochloric acid concentration, Sodium chlorate concentration, solution temperature, leaching time on the gold leaching rate was studied. Gold can be effectively leached out from gold-bearing material by the process of chlorination leaching, displaced using iron powder and the secondary chlorination roasting of railings. The best results can be obtained with the conditions of 2 ： 1 liquid to solid ratio, 15% hydrochloric acid, 60 kg/t sodium chlorate, 20℃ leaching temperature, 4 hours leaching time, the extraction rate of gold was more than 92% which is higher than the leaching rate used by of cyanide （89.37%）. The leaching time of chlorination was 4 hours quite less than the leaching time of cyanidation （24 hours）. The recovery rates of gold and copper were more than 99% by dis- placed using iron powder.