嗜酸菌作用下黄铜矿表面铁/硫形态转化对其表面钝化的影响和机理研究

Microbially mediated mineral dissolution is a kind of widespread mineral-microbe interaction, including bioleaching of chalcopyrite by acidophiles which plays an important role in many aspects. During bioleaching of chalcopyrite, the passivation layers, formed by aggregation of intermediate products onto the mineral surface, lead to the low leaching rate. Although more studies have observed leaching products relating to passivation layers, the impacting mechanism of passivation is rarely involved, especially the correlation of passivation to leaching process and the microbial iron/sulfur activity. Therefore, the project is to research the iron/sulfur speciation transformation on the surface of chalcopyrite dissolved by acidophiles and mechanism of its impact on surface passivation. On the basis of a variety of means, such as high-resolution spectroscopy, the iron/sulfur speciation transformation and microbial iron/sulfur activity, as well as the impact of environmental parameters will be studied during bioleaching of chalcopyrite, to establish the relation between iron/sulfur speciation and bioleaching efficiency, and elucidate the relatedness and mechanism among surface passivation, microbial iron/sulfur activity and chalcopyrite dissolution pathway. It is expected by this study to provide theoretical and experimental basis of abating passivation and optimizing the industrial bioleaching process of chalcopyrite.

微生物活动促进矿物的分解是一种广泛存在的矿物-微生物作用，其中嗜酸菌作用下黄铜矿的分解是一种典型的生物浸出作用，并具有多方面的重要意义。黄铜矿生物浸出过程中，反应产物可聚集在矿物表面并阻碍其持续分解，造成表面钝化。尽管诸多研究都提到钝化现象并检测到与钝化有关的产物，但钝化制约机制很少涉及，尤其是钝化效应与浸矿菌铁/硫氧化活性及黄铜矿浸出途径的相关性和机理研究缺乏。因此，本项目立题研究嗜酸菌作用下黄铜矿表面铁/硫形态转化对其表面钝化的影响和机理。拟采用多种高分辨光谱学等手段，深入研究黄铜矿生物浸出过程中矿物表面的铁/硫赋存形态和浸矿菌的铁/硫氧化活性及其受环境因素的影响，建立铁/硫赋存形态与黄铜矿生物氧化分解之间的制约关系，探明黄铜矿钝化现象与浸矿菌铁/硫氧化活性及黄铜矿浸出途径的相关性和机制。为寻找合适条件与方法以减弱钝化现象及优化黄铜矿生物浸出工艺提供理论和实验依据。

微生物活动促进矿物的分解是一种广泛存在的矿物-微生物作用，其中嗜酸菌作用下黄铜矿的分解是一种典型的生物浸出作用，并具有多方面的重要意义。本项目针对黄铜矿生物浸出过程中反应产物在矿物表面聚集产生的钝化现象，围绕不同温度特性、不同能量代谢特征典型浸矿菌-黄铜矿相互作用体系，基于同步辐射X射线吸收近边结构（XANES）光谱学等手段研究了黄铜矿生物浸出过程中铁/硫形态转化，解析了关键中间产物和钝化作用及其消解机理；针对关键中间产物S0，基于转录组测序和比较转录组分析研究了外加不同形态S0（α-S8和μ-S）对黄铜矿生物浸出过程中浸矿菌代谢特征的差异影响，结合密度泛函理论（DFT）计算，解析了其促进或抑制浸出的分子机制。此外，还针对典型浸矿菌和浸出过程中产生的重金属砷离子，研究了外加As(III)离子条件下典型嗜酸菌铁硫氧化还原作用及其耦合As(III)归趋的相关机制。.针对上述研究内容，所取得的主要成果为：（1）揭示了嗜酸菌作用下黄铜矿表面的铁/硫赋存形态转化及其与钝化作用产生和消解的关联性，阐明了外加条件对黄铜矿生物浸出的钝化/强化作用的分子机制。（2）发展了基于同步辐射高分辨光谱学、微生物组学和DFT计算联合表征矿物-微生物相互作用的方法。（3）参加国内学术交流会议3次，国际学术交流会议1次。（4）发表文章12篇，专著1部，培养硕士生3名。.这些研究成果为阐明黄铜矿钝化现象与黄铜矿浸出途径的关联性，进一步加深对黄铜矿浸出机理的认识奠定了理论基础，也为寻找合适条件与方法以减弱钝化现象及优化黄铜矿生物浸出工艺提供理论和实验依据。