College of Natural Sciences, Bangor University, Deiniol Road, Bangor, LL57 2UW, UK.
Appl Microbiol Biotechnol. 2014;98(14):6297-305. doi: 10.1007/s00253-014-5687-6. Epub 2014 Apr 1.
An oxidized lateritic ore which contained 0.8 % (by weight) copper was bioleached in pH- and temperature-controlled stirred reactors under acidic reducing conditions using pure and mixed cultures of the acidophilic chemolithotrophic bacterium Acidithiobacillus ferrooxidans. Sulfur was provided as the electron donor for the bacteria, and ferric iron present in goethite (the major ferric iron mineral present in the ore) acted as electron acceptor. Significantly more copper was leached by bacterially catalysed reductive dissolution of the laterite than in aerobic cultures or in sterile anoxic reactors, with up to 78 % of the copper present in the ore being extracted. This included copper that was leached from acid-labile minerals (chiefly copper silicates) and that which was associated with ferric iron minerals in the lateritic ore. In the anaerobic bioreactors, soluble iron in the leach liquors was present as iron (II) and copper as copper (I), but both metals were rapidly oxidized (to iron (III) and copper (II)) when the reactors were aerated. The number of bacteria added to the reactors had a critical role in dictating the rate and yield of copper solubilised from the ore. This work has provided further evidence that reductive bioprocessing, a recently described approach for extracting base metals from oxidized deposits, has the potential to greatly extend the range of metal ores that can be biomined.
一种含有 0.8%（按重量计）铜的氧化红土矿，在 pH 和温度控制的搅拌反应器中，在酸性还原条件下，使用嗜酸化能自养菌氧化亚铁硫杆菌的纯培养物和混合培养物进行生物浸出。硫作为细菌的电子供体，而针铁矿（矿石中主要的三价铁矿物）中存在的三价铁作为电子受体。与有氧培养或无菌缺氧反应器相比，细菌催化的红土矿还原溶解可浸出更多的铜，矿石中高达 78%的铜被浸出。这包括从酸不稳定矿物（主要是铜硅酸盐）中浸出的铜和与红土矿中三价铁矿物结合的铜。在厌氧生物反应器中，浸出液中的可溶性铁以二价铁形式存在，铜以一价铜形式存在，但当反应器充气时，这两种金属都迅速被氧化（转化为三价铁和二价铜）。添加到反应器中的细菌数量对从矿石中溶解铜的速率和产量具有关键作用。这项工作进一步证明了还原生物加工（一种最近描述的从氧化矿床中提取基础金属的方法）有可能大大扩展可生物提取的金属矿石范围。
