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

氧化亚铁硫杆菌是黄铜矿细菌浸出研究中常用的菌种。氧化亚铁硫杆菌在细菌浸出过程中产生的胞外物质会影响黄铜矿中铜的浸出。在生态系统中，一些细菌分解或消化来自其他细菌的细胞外物质。本研究选用嗜酸固氮菌Beijerinckia indica分解氧化亚铁硫杆菌胞外物质，考察其共存对氧化亚铁硫杆菌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，研究了添加活性炭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值为1.7。为了适应低pH条件下的生长，将印度拜氏酵母培养物依次接种到pH从3.0开始逐渐降低的培养基中。然而，B. indica在低于pH3.0时不生长。采用氧化亚铁硫杆菌和印度B杆菌混合培养，在初始pH = 3.0条件下进行细菌浸出试验，对铜的浸出没有促进作用.在黄铜矿细菌浸出过程中，活性炭的加入促进了铜的浸出。在加活性炭和不加活性炭的条件下，细菌浸出35天后铜的浸出率分别为55%和10%。铜的萃取量随活性炭粒径的减小而增加。

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.