Effect of nitrogen fixing bacteria on the bacterial leaching of chalcopyrite by Thiobacillus ferrooxidans

氧化亚铁硫杆菌常用于黄铜矿的细菌浸出研究。报道了细菌浸出过程中氧化亚铁杆菌胞外物质对黄铜矿铜的浸出有影响。在生态系统中，一些细菌分解或消化形成其他细菌的胞外物质。在本研究中，我选择了一种嗜酸固氮生物Beijerinckia indica来分解T.ferrooxidans的胞外物质，并研究了其共存对T.ferrooxidans细菌浸出黄铜矿的影响。众所周知，活性炭吸附有机离子。因此，还研究了活性炭的添加对黄铜矿生物浸出的影响。初步试验表明，细菌浸出黄铜矿的最佳pH为1.7。为了适应低pH条件下的生长，在pH从3.0开始逐渐降低的培养基中依次接种北杰林克菌培养物。在pH3.0以下，B.indica不生长。在初始pH为0 ~ 3.0的条件下，采用氧化亚铁杆菌和印度杆菌混合培养，进行了细菌浸出试验，但铜的浸出率没有提高。在细菌浸出黄铜矿过程中，活性炭的加入加速了铜的萃取。加活性炭和不加活性炭35 d后，铜的产率分别为55%和10%。铜的提取率随活性炭粒径的减小而增大。

Thiobacillus ferrooxidans is commonly used inthe study on the bacterial leaching of chalcopyrite. It was reported that extracellular substances from T.ferrooxidans during the bacterial leaching could affect the copper extraction from chalcopyrite. In the ecological system, some bacteria decompose or digest extracelular substances form other bacteria. In this study, I chose a acidophilic, nitrogen fixing organism Beijerinckia indica to decompose extracellular substances from T.ferrooxidans, and investigated the effect of its coexistence on the bacterial leaching of chalcopyrite by T.ferrooxidans. It is well-known that activated carbon adsorbs organic ions. Therefo, the effect of addition of activated carbon on the bioleaching of chalcopyrite was also investigated.1. The preliminary experiment showed that optimum pH of the bacterial leaching of chalcopyrite was 1.7. In order to adapt to grow at the low pH, the culture of Beijerinckia indica was sequentially inoculated in the medium with decreasing pH of it from 3.0. Howeber, B.indica did not grow below pH3.0. A bacterial leaching test was carried out using a mixed culture with T.ferrooxidans and B.india at the initial pH 0f 3.0, but the copper extraction was not enhanced.2. The addition of activated carbon accelerated the copper extraction in the bacterial leaching of chalcopyrite. The yield of copper after 35 days of bacterial leaching with or without lg of activated carbon were respectably 55% and 10%. The amount of copper extraced increased with decrease in the particle size of activated carbon added.