氧化亚铁硫杆菌浸矿体系中黄铁矿的电化学行为(英文)

运用循环伏安、稳态极化扫描和交流阻抗等电化学测试方法,研究黄铁矿在氧化亚铁硫杆菌浸矿体系和无菌酸性体系下的电化学氧化机理。结果表明,在无菌和A.ferrooxidans菌存在的条件下,黄铁矿的氧化反应分为两步:第一步是黄铁矿氧化生成元素S;第二步是元素S被氧化生成SO42-。加入A.ferrooxidans后黄铁矿的氧化机理没有发生改变,但是氧化速度加快。随着黄铁矿与A.ferrooxidans作用时间的延长,极化电流密度增加,黄铁矿表面钝化膜溶解的点蚀电位降低。在细菌存在的条件下,电极的阻抗值下降,表明微生物的存在加速了黄铁矿电极的腐蚀作用,有利于黄铁矿的氧化溶解。     

嗜热硫氧化硫化杆菌与喜温嗜酸硫杆菌混合浸出铁闪锌矿研究

采用正交试验, 通过考察温度、pH值、喜温嗜酸硫杆菌接种时间和喜温嗜酸硫杆菌接种浓度4个因素, 研究硫氧化硫化杆菌与喜温嗜酸硫杆菌混合菌对铁闪锌矿浸出的影响。试验结果表明: 氧化硫细菌的加入, 有助于消除铁闪锌矿浸出过程中生成的、覆盖在矿物表面的元素硫, 使得硫氧化硫化杆菌和喜温嗜酸硫杆菌混合菌浸出铁闪锌矿的效果比单一硫氧化硫化杆菌浸出效果好; 混合菌浸出铁闪锌矿时浸出率达到54.2%, 而单一硫氧化硫化杆菌浸出时浸出率为46.8%。正交试验结果统计分析表明混合菌浸出铁闪锌矿的最优条件为: pH=1.8、第3 d接种喜温嗜酸硫杆菌和喜温嗜酸硫杆菌接种浓度2.5×10⁶个/mL; 其中pH值是影响混合菌浸出铁闪锌矿的主要因素, 其次是喜温嗜酸硫杆菌接种浓度及喜温嗜酸硫杆菌接种时间。     

Formation of passivation film during pyrrhotite bioleached by pure L. ferriphilum and mixed culture of L. ferriphilum and A. caldus

Bioleaching and electrochemical experiments were conducted to evaluate pyrrhotite dissolution in the presence of pure L.ferriphilum and mixed culture of L. ferriphilum and A. caldus. The results indicate that the pyrrhotite oxidation behavior is the preferential dissolution of iron accompanied with the massive formation of sulfur in the presence of L. ferriphilum, which significantly hinders the leaching efficiency. Comparatively, the leaching rate of pyrrhotite distinctly increases by 68% in the mixed culture of L. ferriphilum and A. caldus at the 3rd day. But, the accumulated ferric ions and high p H value produced by bioleaching process can give rise to the rapid formation of jarosite, which is the primary passivation film blocking continuous iron extraction during bioleaching by the mixed culture. The addition of A. caldus during leaching by L. ferriphilum can accelerate the oxidation rate of pyrrhotite, but not change the electrochemical oxidation mechanisms of pyrrhotite. XRD and SEM/EDS analyses as well as electrochemical study confirm the above conclusions.     

嗜铁钩端螺旋菌对黄铜矿表面性质的影响(英文)

通过吸附、动电位、接触角和摇瓶浸出试验研究Leptospirillum ferriphilum菌作用前后黄铜矿表面性质的变化。采用不同能源物质(亚铁和黄铜矿粉)培养L.ferriphilum菌。结果表明,细菌可以很快吸附在黄铜矿表面,并且固体能源物质培养的细菌比液体能源物质培养的细菌可以更多、更快地吸附在矿物表面。与细菌作用后,黄铜矿的等电点朝着细菌等电点的方向移动。在添加与不添加能源物质时,黄铜矿的接触角表现出不同的变化趋势。XRD、SEM/EDS检测表明浸出过程中在黄铜矿表面生成了硫和黄钾铁矾。通过EDS检测可知在黄铜矿的分解过程中,铁优先从黄铜矿表面释放出来。在浸出过程中黄铜矿表面生成了钝化层,从而导致其浸出率很低。通过研究推测钝化层的主要成分是硫,而不是黄钾铁矾。     

铁闪锌矿的Leptospirillum ferrooxidans菌浸出及电化学性能(英文)

采用纯种L.ferrooxidans菌研究矿浆浓度、pH及外加Fe3+离子对铁闪锌矿生物浸出的影响。结果表明,锌的浸出率随着矿浆浓度的降低而增加。在生物浸出过程中调节pH值到1.6对铁闪锌矿的溶解有促进作用。外加Fe3+离子加速了铁闪锌矿的生物浸出,但当外加Fe3+离子浓度超过2.5g/L时,促进作用变弱。这是因为高浓度的Fe3+离子会对细菌生长产生抑制作用且促进黄钾铁矾的生成。在L.ferrooxidans菌存在条件下,利用电化学测试方法进一步了解有、无外加Fe3+离子时铁闪锌矿的溶解过程。实验数据表明,外加Fe3+离子可以增加腐蚀电流密度,有利于锌的提取。交流阻抗谱表明,添加Fe3+离子后没有改变反应过程的控制步骤。     

Bioleaching and electrochemical properties of chalcopyrite by pure and mixed culture of Leptospirillum ferriphilum and Acidthiobacillus thiooxidans

The bioleaching of chalcopyrite was investigated using a pure and mixed culture consisting of iron-oxidizing Leptospirillum ferriphilum (L. ferriphilum) and sulfur-oxidizing Acidthiobacillus thiooxidans (A. thiooxidans). The electrochemical tests were conducted to investigate the bioleaching behavior of chalcopyrite by various bacteria. Bioleaching efficiency of chalcopyrite in mixed culture is higher than that in the pure culture of L. ferriphilum alone. The iron-oxidizing L. ferriphilum plays a dominant role during bioleaching of chalcopyrite in the mixed culture of L. ferriphilum and A. thiooxidans. During bioleaching, certain values of redox potential are beneficial to the decomposition of chalcopyrite. Jarosite and sulfur are observed as products of bioleaching. The addition of A. thiooxidans during leaching by L. ferriphilum can change the electrochemical control steps of leaching. The corrosion current density is substantially promoted in the culture involving bacteria, especially in the mixed culture.