紫金山铜矿浸出过程黄铁矿的氧化行为

Bio-oxidation of pyrite during copper bioleaching in Zijinshan

针对紫金山铜矿堆浸过程中,在辉铜矿和铜蓝等有用矿物浸出的同时,有黄铁矿被大量浸出,造成浸出液中Fe3+浓度过高的现状,研究了细菌浸出黄铁矿的氧化行为和机理,重点考察了Fe3+的化学氧化以及细菌浸出黄铁矿过程的影响因素.研究结果表明,在有菌条件下,pH值为1.6时,混合矿浸出初期,黄铁矿的浸出率仅为5%～8%;随着浸出时间的增加,氧化还原电位升高,浸出15d后,氧化还原电位上升到500mV以上时,黄铁矿的浸出率可达25%.说明氧化还原电位是细菌浸出黄铁矿过程的重要影响因素.机理研究表明,细菌浸出黄铁矿是以间接反应为主,细菌在黄铁矿表面的吸附对黄铁矿的浸出具有协同作用.

During Zijinshan copper heap-leaching, lots of pyrite was leached and Fe^3＋ concentration was higher in solution with chalcocite and covellite leached. The oxidation behavior and mechanism of pyrite bioleaching, especially the chemical oxidation of Fe^3＋ and the influential factors of pyrite bioleaching were studied. The results showed that the pyrite leaching rate is 5 % - 8 % when the pH value of solution was 1.6 and bacteria was in presence during composite leaching process at the initial stage. The redox potential of solution increases with the bioleaching time prolonging, After 15 d, when the redox potential was 500 mV, the pyrite leaching rate was over 25 %. It was indicated that the higher redox potential was an important influential factor in pyrite bioleaching. The research on bioleaching mechanism showed that the indirect action of bacteria gave priority to the direct attack of microbial cells in pyrite bioleaching, and the attachment of bacteria to pyrite surface was synergetic effect to pyrite bioleaching.