This study investigated two bioleaching strategies for removing heavy metals from three mine tailings fractions generated by flotation processes. On the one hand, bioleaching with microbial consortia of acidophilic mesophiles and moderate thermophiles efficiently extracted Co, Cu, Zn, and As, while the leaching of Pb was facilitated through the use of organic acids produced by a heterotrophic bacterium and a fungus. Approximately 100% Co, 68% Zn, 63% As, and 31% Cu were bioleached with acidophilic mesophiles from the barite tailings (BT) sample after 14 days, whereas for the barite concentrate (BC) sample the results showed about 100% Co, 70% Zn and As, and 45% Cu removal at the same period. The sulfide concentrate (SC) sample underwent bioleaching with both consortia, acidophilic mesophiles and moderate thermophiles over 28 days. Approximately, 67% of Co, 28% of Zn, 56% of As, 28% of Cu, and 6% of Mn were extracted from the sample using mesophiles, whereas the leaching efficiency with the moderate thermophiles was about 72% of Co, 50% of Zn, 28% of As, 36% of Cu, and 5% of Mn in 20 L bioreactors. On the other hand, bioleaching of Pb was explored using the bacterium and the fungus for the production of gluconic acid and citric acid, respectively. Additionally, besides glucose-based media, glycerol and crystal sugar were tested as alternative and cheaper carbon sources. The metabolic activity of allowed a maximum Pb leaching of 39–43% from the BT sample in 28 days in glycerol-based medium, while for the BC sample, the maximum Pb extraction was around 60% in glucose-based medium. A lower extraction of Pb was achieved with for both samples. The maximum extraction of 34% and 39% of Pb was reached within 7 days when glucose was used as the carbon source. Further optimization should address both the enhancement of metals removal and – especially for the organic acid bioleaching – the reduction of costs related to media formulation and fungal biomass production on a larger scale.

中文翻译：

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生物浸出从尾矿浮选部分中去除金属

本研究研究了两种生物浸出策略，用于从浮选过程产生的三种尾矿部分中去除重金属。一方面，利用嗜酸中温菌和中度嗜热菌的微生物群落进行生物浸出可以有效地提取钴、铜、锌和砷，而通过使用异养细菌和真菌产生的有机酸促进铅的浸出。14 天后，重晶石尾矿 (BT) 样品中的嗜酸性嗜温菌生物浸出大约 100% Co、68% Zn、63% As 和 31% Cu，而对于重晶石精矿 (BC) 样品，结果显示大约 100% Co ，同时去除 70% Zn 和 As，以及 45% Cu。硫化物精矿 (SC) 样品与嗜酸中温微生物和中度嗜热微生物一起进行了 28 天的生物浸出。使用嗜温菌从样品中提取大约 67% 的 Co、28% 的 Zn、56% 的 As、28% 的 Cu 和 6% 的 Mn，而中等嗜热菌的浸出效率约为 Co 的 72%， 20 L 生物反应器中含有 50% Zn、28% As、36% Cu 和 5% Mn。另一方面，利用细菌和真菌分别生产葡萄糖酸和柠檬酸，探索了 Pb 的生物浸出。此外，除了基于葡萄糖的培养基外，还测试了甘油和冰糖作为替代且更便宜的碳源。在基于甘油的培养基中，28 天内，BT 样品的代谢活性允许最大 Pb 浸出量为 39-43%，而对于 BC 样品，在基于葡萄糖的介质中，最大 Pb 萃取率为 60% 左右。两个样品的 Pb 提取率均较低。以葡萄糖为碳源时，7天内Pb的最大萃取率达到34%和39%。进一步的优化应该解决金属去除的增强问题，以及——特别是有机酸生物浸出——降低与大规模培养基配方和真菌生物质生产相关的成本。