原地浸出采铀物理化学渗流机理与渗漏范围预控

The in-situ leaching of uranium is a typical process of physico-chemical percolation, which is associated with a certain degree of pollution to groundwater. In order to efficient exploitation of sandstone uranium resources in China, to carry out tha physico-chemical percolation law of leaching solution in situ leaching and the study of leakage range prediction and prediction is very necessary. This project is based on the in-situ leaching of low permeability sandstone uranium deposits in China. The methods of indoor and outdoor experiments, theoretical analysis, physical simulation and numerical simulation will be used. Based on the fractal theory, we study the void distribution and void surface fractal characteristics of ore rock and the evolution of micro pore structure and uranium leaching characteristics of sandstone and its influence on the solution flow, and establish fractal percolation model. This paper studies the flow field and the change of seepage boundary, and reveals the law of physico-chemical percolation. Through theoretical analysis and physical simulation experiment, the coupled dynamic model and mathematical mode of leaching solution in situ leaching are established, and numerical simulation is develop. Taking a dip mine as an example, the numerical simulation of the factors of physico-chemical percolation process, pumping and injecting liquid volume and well spacing in-situ leaching of uranium on seepage and seepage effects on the regional distribution is carried out. The variation rule of permeability and solution of seepage flow path are obtained. The prediction and control of seepage range and leakage range are realized.

地浸采铀是典型的物理化学渗流过程，伴随着对地下水一定程度的污染。为了高效、环保地开采我国砂岩铀矿资源，开展地浸过程溶浸液的物理化学渗流规律和渗漏范围预测与控制研究是十分必要的。本项目以我国低渗透性砂岩铀矿地浸开采为对象，采用室内外实验、理论分析、物理模拟与数值模拟相结合的方法开展研究。基于分形理论，研究矿岩空隙分布与空隙表面形貌分形特征和铀砂岩浸出前后微观空隙结构演化特征以及其对溶浸液渗流的影响，建立分形渗流模型。研究渗流边界流场和渗流边界形貌变化，揭示地浸过程中的物理化学渗流规律。通过理论分析和物理模拟实验，研究建立地浸过程溶浸液渗流耦合动力学模型及数学模型，开展数值模拟。以某地浸矿山为例，开展地浸采铀的动力学过程、物理化学渗流过程、抽注液量、井型与井距等各种因素对渗流与渗流区域分布影响的数值模拟研究，获得渗透性变化规律和溶浸液渗流流线轨迹，实现对渗流范围和渗漏范围的预测与控制。

开展低渗透性砂岩铀矿床地浸开采的理论与技术研究，对我国铀资源的开发和地浸矿山地下水环境保护具有重大的战略意义。本项目以我国含铀砂岩以及原地浸出矿山为主要研究对象，开展了铀浸出分形动力学特征、含铀砂岩孔隙结构分形表征以及铀浸出过程中矿岩孔隙结构演化规律和物理化学渗流特征的实验研究；研发了铀浸出过程物理化学渗流特征研究的实验装置并开展相关的实验；建立了原地浸出过程耦合动力学数字模型和数值模拟方法，实施了溶质运移迁移模拟研究。本项目的主要发现如下：1）铀浸出速率主要由扩散反应控制，铀矿溶解的最佳矿岩颗粒分布分形维数为2.0。2）我国可地浸含铀砂岩孔隙结构具有良好的双重分形特征，分形的拐点可以把孔隙分为大孔和小孔。粒径分形维数、孔隙体积分形维数、比表面积分形维数和二维分形维数与浸出率均有显著的相关性，孔隙结构对铀的浸出率有显著影响。3）进一步的验证了铀浸出过程为典型的物理化学渗流过程，其渗透性受到浸出过程中矿岩孔隙结构演化的动态影响，铀浸出过程大致分三个阶段。4）受溶浸液流体粘度的影响，浸出从非饱和渗流到饱和渗流经过的时间存在规律性差异，粘度大的溶浸液流体延长了渗流从非饱和态达到饱和态的时间。5）研究建立的原地浸出过程耦合动力学数字模型和数值模拟方法能很好的模拟溶质运移迁移规律，可以判断溶质向采区边缘迁移的路径与距离。以上研究结果为我国原地浸出采铀工艺参数的优化设计和地浸采铀矿山地下水污染控制提供了重要实际应用价值。