难浸金精矿生物预氧化过程中细菌浸出液含金的原因及其控制

Study on Reasons of Existence of Gold in Bacterial Leaching Solution Used in Biological Pre oxidation Process for Extraction of Gold from Refractory Gold Concentrates and Its Control

难浸金精矿生物预氧化菌液中含金的主要原因是金以极微细的颗粒悬浮于细菌浸出液中 ,其沉降速度极慢。通过选择合理的磨矿细度 ;对单层浓密机实施高效改造 ;缩短细菌预氧化时间 ;控制末级氧化的 pH值在 1 .2～ 1 .5;添加絮凝剂加快固体颗粒的沉降速度等几项控制措施 ,将菌液中金的含量降低到 0 .0 1mg/L以下 。

Causes for existence of gold in bacterial leaching solution used in biological pre oxidation process for extraction of gold from refractory gold concentrates were studied in this work. The principal reason is that gold as fine particles suspends in the bacterial leaching solution and precipitates with very low speed. The results from the study indicate that the problem can be resolved by: ① selecting the reasonable sample granule size, ② improving efficiency of the mono layer concentrator, ③ shortening biological pre oxidation time, ④ controlling pH of bacterial leaching solution in the last step at 1.2 to 1.5, ⑤ adding flocculent to speed up precipitation of fine gold particles suspended in the bacterial leaching solution. All these measures can control gold in bacterial leaching solution to less than 0.01 mg/L.