表面活性剂吐温20对胶硫钼矿生物浸出的促进机理

Catalytic influence of surfactant Tween 20 on the bioleaching of Jordisite

为提高胶硫钼矿中钼的生物浸出效率,研究了非离子表面活性剂吐温20对氧化亚铁硫杆菌（A.ferrooxidans）的代谢活性以及胶硫钼矿生物浸出的影响,并采用X射线衍射、扫描电镜对浸出产物进行表征.研究结果表明,吐温20对A.ferrooxidans氧化Fe^（2＋）有明显的抑制作用,但对S0的氧化则表现出一定的促进作用.吐温20对胶硫钼矿生物浸出的作用表现为：低质量浓度促进,高质量浓度抑制,当其质量浓度为30 mg·L^（-1）时,浸出40 d,Mo的浸出率由未添加时的42.21%提高至54.10%.吐温20的加入强化了浸出过程中间产物S0的生物氧化作用,提高了体系中细菌浓度,同时削弱了矿物表面生成的黄钾铁矾和单质硫的钝化作用,从而促进了胶硫钼矿的氧化与溶解.

Jordisite（ Mo S2） is one of the most difficult minerals to deal with in the development of molybdenum-containing mineral resources because of its characteristics of fine molybdenum content,low liberation degree,easiness of slime formation,and poor floatability. Much attention has been paid to develop an effective,economical,and eco-friendly processing method. In this study,a nonionic surfactant Tween 20 was used to improve the leaching of jordisite in the presence of Acidithiobacillus ferrooxidans. The effects of Tween 20 on the metabolic activity of A. ferrooxidans and on the bioleaching of jordisite were tested. After the bioleaching process,the jordisite was characterized by X-ray diffractometry（ XRD） and scanning electron microscopy（ SEM）. The results indicate that the addition of Tween 20 has a negative effect on the Fe^（2＋）-oxidizing activity of A. ferrooxidans,but it is favorable for the sulfur-oxidizing activity of the bacteria. When added in low and high concentrations,Tween 20 enhances and reduces the bioleaching efficiency of jordisite,respectively; thus,it has a significant influence on the bioleaching. After 40 days,a dosage of 30 mg·L^（-1） Tween 20 increases the molybdenum extraction yield from 42. 21% to 54. 10% compared with the bioleaching without Tween 20. It is found that the presence of Tween 20 can accelerate the bio-oxidation of the elemental sulfur generated in the jordisite bioleaching process,consequently increasing the bacteria concentration. Meanwhile,Tween 20 addition reduces the amount of jarosite and elemental sulfur present on the minerals surface,weakening the passivation layer on the minerals surface. This accelerates the jordisite dissolution process,thereby increasing the molybdenum leaching efficiency.