氧化亚铁硫杆菌对黄铜矿的生物氧化研究

针对矿区硫化矿氧化产生的酸性矿山废水(AMD)对生态环境造成严重影响的问题,以矿区常见的黄铜矿(CuFeS2)为研究对象,采用已筛选的氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans,简称A.f菌)为实验菌株,探讨在A.f菌作用下黄铜矿的氧化过程。实验结果表明,A.f菌可显著促进黄铜矿的氧化,第18天有菌体系中的铜离子浓度是无菌体系中的5倍;同时细菌可促进溶液中Fe2+氧化为Fe3+,使氧化还原电位升高,从而对黄铜矿保持较高的氧化速率,并导致体系的pH值降低;还发现黄铜矿的氧化过程中可形成中间产物方黄铜矿(CuFe2S3),而细菌氧化还可产生硫磷化钴(CoPS),中间产物的形成并没有明显延缓黄铜矿的氧化速率;生物氧化可造成矿样表面侵蚀多坑,可能是细菌对黄铜矿的直接氧化作用造成的。由于黄铜矿的生物氧化明显控制其氧化进程,抑制黄铜矿的生物氧化对酸性矿山废水的源头治理具有十分重要的意义。

Bio-oxidation of Chalcopyrite by Acidithiobacillus ferrooxidans

As acid mine drainage (AMD) derived from oxidation of sulphides in the mining area has a strong impact on ecological environment, this paper examined the oxidation process of chalcopyrite by Acidithiobacillus ferrooxidans (A. ferrooxidans). Results showed that A. ferrooxidans significantly promoted the oxidation rate of chalcopyrite. At the end of the experiment, the concentrations of copper ions in the bacterial system were 5 times those in the sterile system. Moreover, bacteria in the solution could enhance the oxidation of Fe²⁺ to Fe³⁺, and increase redox potential of solution, thus leading to a high oxidation rate of chalcopyrite and a low pH value of the solution. During the oxidation process, an intermediate isocubanite (CuFe₂S₃) might be formed in the sterile system, whereas cobalt phosphide sulfide (CoPS) was produced only in the bacterial system. However, the formation of intermediate products did not significantly decrease the oxidation rate of chalcopyrite. In addition, direct oxidation mechanism was possibly confirmed as more erosion pits were observed on the surface of bio-oxidized ore samples. Therefore, it is important to control bio-oxidation of chalcopyrite for AMD source treatment because bio-oxidation is a key point in the process of chalcopyrite oxidation.