基于铀矿石生物堆浸过程的溶质迁移－矿物变化特征研究

Uranium resource is the basic material for nuclear power running. With the difficulty of development of low grade uranium resources with large reserves, new leaching technology is urgent to be promoted for those resources. Although bioleaching technology has many advantages obviously, people do not understand well on the mechanism of solute migration - mineral characteristics during uranium heap bioleaching that lead to heap bioleaching in uranium ore unsuccessfully in our country. This project takes one of the largest hard rock type uranium deposits as our study object. Based on the fully research on ore compositions and use of our independent bacteria, heap bioleaching tests of uranium are conducted. CT and digital image processing technology are adopted to study the pore structure evolution in particles and its relationship with hydraulic parameters. Hydrogeochemical modeling method is used to study the relationship of pyrite, uranium mineral and chemical compositions of the solute, and the mechanism of bacteria and solute transportation and mineral characteristic changing. Thus the interactions between water & rock & bacterial and the factors which affects the uranium ore’s oxidation are determined also. This will help us to reveal the mechanism of heap bioleaching for uranium and, as well, to enrich and to perfect our heap bioleaching basis theorys and technologies.

铀矿资源是核电发展的基础，研发占有相当储量的低品位铀资源提取新技术是一项亟待解决难题。尽管微生物浸矿技术优势明显，但因人们对微生物浸铀过程中溶质迁移-矿物变化特征机理认识尚不深入，致使微生物铀矿堆浸国内还未见成功案例。本课题以相山铀矿为对象，在系统分析矿石物质组成基础上，利用自主研发的菌群，开展一系列生物浸铀试验。采用CT和数字图像处理技术研究孔隙结构演化规律及其与渗流参数的关系，运用水文地球化学模拟技术研究生物浸铀过程中黄铁矿、铀矿物和溶质化学组分演化规律，以及融“矿物变化-溶浸液-生物”为一体的多因素溶质迁移规律，并建立“生物-溶质运移-矿物变化”的关系，进而确定影响细菌氧化铀矿石过程的相关因素及相应水－岩－生物作用规律，揭示生物堆浸浸铀作用机制，使铀矿生物堆浸基础理论与方法更加丰富和完善。

铀矿资源是核电发展的基础，随着我国铀资源开发难度的加大，研发低品位铀资源新提取技术是当前十分迫切的难题。微生物浸铀过程中溶质迁移与矿物作用机理对提高铀的浸出至关重要。本项目以我国最大的硬岩铀矿山相山铀矿为对象，在研究矿石物质组成、化学成分的基础上，开展生物浸铀试验。表明在同一喷淋强度、接种比、酸化酸度等工艺条件下，粒度大小对铀浸出起决定性作用。运用微米CT分析揭示了浸铀过程中酸化前原矿、酸化后以及菌浸后孔隙变化特征，表明铀等矿物的溶解浸出与矿石颗粒孔隙的变化相关，铀矿物溶解浸出，增大矿石颗粒内部孔隙，颗粒间的孔隙变化则受浸出过程重力压缩和化学溶蚀的双重作用。浸出过程中铀和钙、镁及铝离子浓度的变化与矿石颗粒孔隙的变化呈正相关。浸出液中钙、镁、铝等主要离子和铀含量越高，矿石中被溶解的矿物越多，矿石颗粒内的孔隙度增大。浸出过程地球化学模拟研究表明浸出液中石膏和硬石膏发生沉淀作用，浸出过程中石膏发生沉淀，减小了矿石的孔隙率，不利于铀浸出。课题最后建立了“生物-溶质运移-铀矿石矿物变化特征”的关系，确定了影响细菌氧化铀矿石过程的相关因素及相应水－岩－生物作用规律的关系，初步揭示了生物堆浸浸铀作用机制。