铀矿石U/Fe/S物相对铁硫氧化细菌菌群浸矿行为的引导作用机制研究

It is difficult to maintain the activities of bioleaching microorganisms in the uranium bioleaching system because of its openness. The instability of microbial activities and orientation to form passivation layer have become to the two scientific puzzles which have to be urgently solved. Therefore, a new idea has been proposed based on the previous research results in this project. It is that the regulation of the U/Fe/S phase in uranium ores could provide a direction for the community dynamics and metabolic mechanism, and then change the bioleaching behaviors and the metabolite production. It would maintain a stable microbial community and high iron/sulfur oxidizing activities, and meanwhile, could reduce the production of passivation substance and change the structure, and therefore it would make a better uranium bioleaching performance. In the proposed project, the low-grade uranium ores with obviously different U/Fe/S phases will be selected as the research objective. Driving mechanism of U/Fe/S phase to bioleaching behaviors of iron/sulfur oxidizing bacterial consortia will be explored. It will make uranium mineral phase and bioleaching bacterial consortia match better each other, and the iron and sulfur metabolic activities of bioleaching bacterial consortia can be improved. Meanwhile, the amount and compactness of passivation layer can be reduced. As results, the project will provide valuable references to solve the two scientific puzzles above. Meanwhile, it is theoretically meaningful to enrich the synergistic metabolism theory of iron/sulfur oxidizing bacteria and the synergistic decomposition theory of minerals.

在微生物浸铀这一开放体系中很难保持浸矿微生物的活性，也很难调控浸矿微生物的行为，因而浸矿微生物性能不稳定、易形成钝化层已成为亟待解决的科学难题。为此，本项目在前期实验研究基础上提出一个新设想：通过调节铀矿石U/Fe/S物相对来引导铁硫氧化细菌菌群的群落动态及代谢机制，进而引导其浸矿行为与代谢产物的产生，使其维持一个稳定的菌群结构与较高的铁硫氧化活性，同时减少钝化物的形成并改善其结构，从而提高其浸铀效率。拟以U/Fe/S物相差异明显的低品位铀矿作为研究对象，探索U/Fe/S物相对铁硫氧化细菌菌群浸矿行为的引导作用机制，从而使矿物物相与浸矿菌群更加匹配，充分发挥浸矿菌群的铁硫代谢作用，同时降低钝化物的产生量与致密度。其研究成果将为解决浸铀微生物性能不稳定、易形成钝化层两大难题提供有价值的指导作用，也对丰富铁/硫氧化细菌协同代谢和矿物协同氧化理论具有重要意义。

本项目针对浸矿微生物浸铀性能不稳定、易形成钝化层的难题，围绕铀矿石 U/Fe/S 对铁硫氧化细菌菌群浸铀行为的引导作用机制这一关键科学问题，取得了以下四个方面的研究结果。研究了细菌浸铀过程中U/Fe/S比对浸铀效果的影响，确定了细菌菌群浸出低品位铀矿不同浸矿方式的最佳U/Fe/S比范围，溶液中较佳Fe/S比为5：0.5-5，矿石中较佳U/Fe/S比为1：10：0.2-0.4；研究了铁硫比对细菌浸铀过程中钝化物形成及矿渣表面特性的影响，适当的铀铁硫比会改变钝化物的结构，改善钝化物的孔隙率，提高铀浸出率，阐明了Fe/S比对钝化物形成的作用机制；研究了铁硫比对细菌浸铀过程中菌群在溶液中及矿石表面的演替规律，结果表明矿石中合适的U/Fe/S比有助于维持附着矿石表面的铁氧化菌和硫氧化菌的动态平衡，并产生协同代谢作用，从而更为有效地分解铀矿石，揭示了U/Fe/S对菌群分布动态的引导机制及其对矿石作用模式的影响机制；且构建了某复杂低品位铀矿浸出的动力学模型，最终构建了铁硫比对细菌浸铀的作用机理模型及柱浸体系不同矿层的细菌作用机理模型。上述结果可为细菌菌群浸出复杂难浸低品位铀矿工艺的实践应用及产业化提供一定的理论依据与指导价值。