基于胶质芽孢杆菌和黑曲霉的赤泥脱硅-淋滤系统构建及机理研究

The valuable metals in red mud can be recovered by bioleaching process. The erosion and destruction of lattice in silicate minerals is the critical factor determining the bioleaching efficiency. Theoretically, biodesilicication can be used to corrode the silicate minerals and promote the leaching performance of valuable metals from red mud. However, few studies were involved in biodesilicication of red mud so far. In this project, biodesilicication process and bioleaching process will be combined to extract metals from red mud. The red mud from Bayer and sintering process will be used as the leaching materials, Bacillus mucilaginosus and Aspergillus niger will be used as the leaching strains, and biodesilicication process, bioleaching process and combined biodesilicication-bioleaching process will be used respectively as the study system in our research. The influence factors in the biodesilicication and bioleaching process will be analyzed and optimized, the thermodynamics and kinetics of leaching process will be investigated, the mechanism of interaction between bacterium, fungus and red mud will be studied, and the objective law of metals leaching, minerals erosion, and microbial metabolism in biodesilicication and bioleaching will be explored. This study can provide data and theories to support the creation of biodesilicication-bioleaching system. Furthermore, a new biological method will be provided for efficiently leaching valuable metals from red mud, and some academic knowledge will be obtained for understanding the interaction between bacteria, fungi and minerals in biohydrometallurgy.

生物淋滤技术可用于浸提赤泥中的有价金属元素，但赤泥中的含硅矿物难以被淋滤菌溶蚀，这限制了硅氧晶格中有价金属的溶出。胶质芽孢杆菌的生物脱硅效应能有效溶蚀赤泥中的含硅矿物，但目前鲜有此方面的研究。本项目拟将生物脱硅与生物淋滤两个过程结合，构建赤泥的脱硅-淋滤混合系统，以期提升赤泥的生物淋滤效率。本项目以拜耳法和烧结法赤泥为淋滤材料，以胶质芽孢杆菌和黑曲霉为脱硅、淋滤菌种，以生物脱硅、生物淋滤和生物脱硅-淋滤混合系统为研究对象，通过测定金属浸出、矿物溶蚀、菌体代谢等指标，研究影响生物脱硅和淋滤的条件因子及其优化区间，分析金属元素浸出的热力学和动力学原理，探讨细菌、真菌和赤泥相互作用过程与机制，最终为构建生物脱硅-淋滤混合系统提供理论支持。该项目能为赤泥中有价金属元素的高效淋滤提供新的思路，亦可深化对生物湿法冶金过程中异养型细菌、真菌、矿物之间相互作用的认知，兼具一定的现实意义和理论研究价值。

赤泥中的含硅矿物难以在生物淋滤过程中被淋滤菌种溶蚀，而硅酸盐细菌的生物脱硅效应能有效溶蚀赤泥中的含硅矿物。本项目以Bacillus mucilaginosus和Aspergillus niger为脱硅、淋滤菌种，将生物脱硅与生物淋滤两个过程有机结合，构建赤泥的生物脱硅-淋滤耦合系统，从而提升赤泥的生物淋滤效率。生物脱硅-淋滤耦合系统在最优条件下Bacillus mucilaginosus的最大生物量为4.58 log(copies/ng DNA)，最大生长速率为1.44 log(copies/ng DNA)/d，生长延滞时间为4.69 d；Aspergillus niger的最大生物量为6.50 log(copies/ng DNA)，最大生长速率为1.33 log(copies/ng DNA)/d，生长延滞时间为1.60 d。耦合系统中多糖最大产量为5.53 g/L，最大产生速率为3.25 mg/(L·d)，多糖代谢的延滞时间为5.31 d。耦合系统中草酸、柠檬酸、葡糖酸、乳酸、酒石酸、苹果酸的最大产量分别2450.70、1482.06、1670.61、96.14、189.45、188.36 mg/L。Bacillus mucilaginosus和Aspergillus niger共同控制的生物脱硅-淋滤耦合系统偏向于液膜扩散控制，Si浸出的反应常数为0.0697，Al浸出的反应常数为0.0763。耦合系统与生物脱硅系统相比Si浸出率提升34.2%，与生物淋滤系统相比有价金属元素Al、Ti、Fe、V、Ga、Ge、La浸出率分别提升52.8%、56.8%、155.6%、71.5%、27.3%、23.4%、51.1%。Bacillus mucilaginosus杆状细胞、Aspergillus niger菌丝以及菌体分泌的多糖等黏性代谢产物通过吸附、链接、贯穿、缠绕、包裹和封装作用将赤泥颗粒聚集于一体，形成细菌-真菌-赤泥聚合体微环境，在微环境中生物脱硅与生物淋滤效应互相强化。在生物脱硅、生物淋滤和生物脱硅-淋滤耦合系统内发生了生物风化与生物成矿现象，铝硅酸盐矿物正长石部分转变为歪长石，碳酸盐矿物方解石和碳酸盐-铝硅酸盐矿物钙霞石易被生物溶蚀破坏，释钙后成为水钙铝榴石的主要钙质来源使其含量显著升高。