基于渗流-化学-应力多场耦合的砂岩型铀矿CO2+O2地浸开采的数值模拟

为探明不同影响因素对CO2+O2地浸采铀效果的影响规律和影响机理,首先建立了适合CO2+O2地浸的渗流-化学-应力多场耦合数值模型,其次,结合实际现场工况,开展了注液速率、渗透率、O2配加浓度、HCO3－配加浓度和铀矿石平均品位对CO2+O2地浸采铀影响的数值模拟研究。研究表明：CO2+O2地浸过程中,抽液井铀浓度呈现“缓慢上升-快速上升-缓慢下降-趋于稳定”的阶段性变化趋势;矿层渗透率、铀矿石平均品位、O2配加浓度、HCO3－配加浓度与抽液井铀浓度呈现线性正相关关系,溶浸液的注入速率与抽液井铀浓度呈现线性负相关关系;CO2+O2地浸过程中应该选择初始渗透率大且铀品位高的矿层,同时应该适当加大O2和HCO3-的配加浓度,并控制好溶浸液注入速率,可实现铀资源的高效开采。本研究对CO2+O2地浸矿层的选择和地浸工艺的优化具有重要的指导意义。

Numerical Simulation of CO2+O2 In-situ Leaching of Sandstone Type Uranium Deposit Based on Multifield Coupling of Seepage-Chemistry-Stress

In order to explore the influence law and mechanism of different influencing factors on CO2+O2 in-situ leaching effect of uranium deposits, firstly, a multi-field coupling numerical model of seepage-chemistry-stress suitable for CO2+O2 in-situ leaching was established, and then, combined with the actual site conditions, the numerical simulation study of the influences of liquid injection rate, permeability, O2 addition concentration, HCO3- addition concentration, and uranium ore average grade on CO2+O2 in-situ leaching uranium were carried out. The results show that during the CO2+O2 in-situ leaching process, uranium concentration in pumped well indicates a phased change trend of "slow rise, rapid rise, slow decline, and stabilize". The permeability of ore seam, average grade of uranium ore, O2 addition concentration, and HCO3- addition concentration show a positive linear correlation with uranium concentration of pumping well, and the injection rate of leaching solution shows a negative linear correlation with uranium concentration of pumping well. During the CO2+O2 in-situ leaching process, uranium deposits with large initial permeability and high uranium grade should be selected, the concentration of O2 and HCO3- should be appropriately increased, and the injection rate of leaching solution should be controlled to achieve efficient exploitation of uranium resources. This study has important guiding significance for site selection and parameter optimization of CO2+O2 in-situ leaching process.