基于铁氧化/还原菌改善黄铁矿-水草酸解液体系下低品位辉铜矿生物浸出过程

Improvement of low-grade chalcocite bioleaching process under the pyrite-aquatic weed acid hydrolysate system based on iron-oxidizing and iron-reducing bacteria

摘要:

[背景] 高效的生物浸出与微生物介导活跃的铁硫代谢紧密关联，低品位辉铜矿（Cu₂S）铁代谢匮乏严重制约其效能。[目的] 强化铁硫代谢及“接触”机制改善低品位辉铜矿生物浸出。[方法] 基于自主筛选的嗜酸杆菌属（Acidiphilium sp.）及双层平板筛选的嗜铁钩端螺旋菌（Leptospirillum ferriphilum），与硫氧化菌喜温嗜酸硫杆菌（Acidithiobacillus caldus）协作，加以Fe²⁺/Fe³⁺-黄铁矿-纤维质废弃物酸解液（废-废资源利用）干预，系统分析浸出生化参数差异性。[结果] 扫描电子显微镜（Scanning Electron Microscope，SEM）结果表明矿渣表面大量微孔及坑壑，表明活跃的菌体作用；傅立叶变换红外光谱仪（Fourier Transform Infrared Spectroscopy，FTIR）揭示N-H、C=O、O-H等键与胞外聚合物（Extracelluler Polymer Substance，EPS）紧密相关，S=O、C-O-S等吸收峰波动表明更剧烈的硫代谢；激光共聚焦扫描显微镜（Confocal Laser Scanning Microscope，CLSM）结果表明优化体系呈现更多附着细胞及EPS，为“接触”机制奠定基础，浸出40 d游离/附着细胞量分别提高2.51倍及5.73倍，最大比生长速率（μ_max）出现时间提前1.5-5.3 d，最高浸出率达67.6%。[结论] 铁氧化/还原菌及外源含铁物质干预强化浸出体系铁硫代谢加速矿物溶解，酸解液促进铁元素循环及菌体生长，附着细胞及EPS分泌增多强化“接触”机制从而有效改善浸出微环境和效能。

Abstract:

[Background] Efficient bioleaching is closely related to the active iron and sulfur metabolism mediated by microorganisms. Thus, the lack of iron metabolism will restrict low-grade chalcocite bioleaching. [Objective] To improve the bioleaching of low-grade chalcocite by enhancing iron and sulfur metabolism and the "contact". [Methods] The iron-oxidizing Leptospirillum ferriphilum (screened with the double-plate method), iron-reducing Acidiphilium sp., sulfur-oxidizing Acidithiobacillus caldus, and the Fe²⁺/Fe³⁺-pyrite-fibrous waste acid hydrolysate system (waste utilization) were combined to improve low-grade chalcocite bioleaching. [Results] A large number of micropores and pits were observed on the slag surface under the scanning electron microscope (SEM), suggesting the active action of the bacteria. Fourier transform infrared (FTIR) spectroscopy revealed that bonds such as N-H, C=O, and O-H were closely related to extracellular polymer substance (EPS), and significantly enhanced absorption peaks of S=O and C-O-S testified more intense sulfur metabolism. Confocal laser scanning microscope (CLSM) manifested that more attached cells and EPS existed in the optimized system, laying the foundation for the "contact" mechanism. After 40 days of leaching, the concentration of planktonic and attached cells increased by 2.51 and 5.73 times, respectively. The maximum specific growth rate (μ_max) appeared 1.5-5.3 days earlier, and the highest cupric ion leaching rate reached 67.6%. [Conclusion] The intervention of iron-oxidizing bacteria, iron-reducing bacteria, and exogenous iron-containing substances strengthens the iron and sulfur metabolism of the leaching system and accelerates the dissolution of minerals. The acid hydrolysate promotes iron circulation and the growth of bacteria. The increase in the number of attached cells and secreted EPS enhances the "contact", thus effectively improving the bioleaching microenvironment and efficiency.