非均质矿层CO_(2)+O_(2)地浸采铀溶浸过程数值模拟与调控

Numerical simulation and regulation of CO_(2)+O_(2) in-situ leaching process in heterogeneous sandstone-type uranium ore

砂岩型含铀储层介质呈空间非均质性,易产生溶浸死角,是造成铀资源浸出率低的主要因素。定量刻画矿层非均质性,评价非均质条件下,地浸采铀水动力和铀浸出过程,以动态调整溶浸剂注入方式控制矿层内部浸铀行为。该文以北方某砂岩型铀矿局部CO_(2)+O_(2)地浸单元为研究对象,采用基于转移概率的地质统计法建立地浸矿层随机岩性结构模型,嵌入CO_(2)+O_(2)地浸采铀反应性溶质运移模型中,采用随机模拟和不确定性分析研究含矿储层介质非均质性对浸铀水动力、溶浸范围和铀浸出过程的影响,基于模拟结果设计抽/注单元布置方案。结果表明:岩性结构的非均质性控制着溶浸过程中地下水位和浸铀浓度的变幅区间,影响铀浸出浓度峰值和峰值到达时间;基于数值模型进行地浸方案的优化调整,可缩短铀矿与溶浸液接触反应时间,提升反应比表面积,以达到提高铀浸出效率的目的。该研究可为开展采区尺度CO_(2)+O_(2)浸出过程的精准模拟和调控提供技术支撑。

Spatial heterogeneity of medium in sandstone-type uranium ore is easy to cause blind-area during in-situ leaching(ISL) of uranium, which is the main factor causing low leaching rate of uranium. Quantitative characterization of lithologic heterogeneity and evaluation of hydrodynamic and uranium leaching process are the premise of dynamically regulating ISL operations to control the uranium-leaching behavior in uranium ore. In this study, geological statistical method based on Transition Probability Geostatistical Software(T-PROGS) is used to establish the random lithologic structure model of the leaching layer, which is embedded in the reactive transport modeling of CO_(2)+O_(2)ISL process of uranium. The stochastic simulation and uncertainty analysis are used to study the effects of lithologic heterogeneity on the uranium leaching process and optimal design of pumping/injection schemes of ISL units. The simulation results of ISL reactive transport model show that the lithologic heterogeneity controls the variation range of groundwater level and uranium leaching concentration, and affects the peak value and peak arrival time of uranium leaching concentration. Optimization and regulation of ISL scheme can shorten the contact reaction time between uranium ore and leaching solution, improve the specific surface area of reaction, and achieve the purpose of improving uranium leaching efficiency. This study provides guidance for the accurate simulation and dynamic regulation of the CO_(2)+O_(2)leaching process of uranium at the scale of large mining areas.