有色金属(冶炼部分)

CO_2+O₂地浸采铀技术因其污染小、成本低，已成为我国砂岩型铀矿床开采的重要方法。在浸出过程中，砂岩型铀矿床孔隙结构演化直接影响溶浸液的渗流及铀的浸出和迁移。因此，深入研究CO_2+O₂地浸采铀过程中砂岩型铀矿床的浸出特性及孔隙演化，对优化浸出工艺和提高铀浸出率具有重要意义。以内蒙古某砂岩型铀矿床为研究对象，系统采集含铀砂岩岩芯样及赋存地下水样，利用自制的地浸采铀模拟试验装置，开展了含铀砂岩岩芯样CO_2+O₂浸出特性及孔隙演化模拟试验，并采用CT扫描等设备对含铀砂岩岩芯样试验前后的孔隙结构进行了表征；同时，运用Avizo软件构建了三维数字岩芯及孔隙网络模型；定量表征了岩芯的孔隙率、孔隙直径等微观孔隙数据。研究结果表明：当液固体积质量比达到24.07 mL/g时，铀浸出率达到64.76%，浸出液铀浓度峰值达到18.47 mg/L；在浸出试验前期和中期，浸出液中HCO₃~–浓度对铀浓度起主导作用，HCO₃~–浓度不低于800 mg/L时，浸铀效果较理想；含铀砂岩岩芯孔隙度由试验前的12.5%提高至试验后的14.4%，孔隙总量减少13%。大孔孔隙(D_eq≥300μm)和中孔孔隙(150μm≤D_eq<300μm)的孔隙数量显著减少，分别为试验前的0.40倍和0.55倍。这些结果对优化CO_2+O₂地浸采铀的浸出性能、相关工艺参数等具有指导意义。

The CO_2+O₂ in-situ leaching technology for uranium mining has become an important method for the exploitation of sandstone-type uranium deposits in China due to its low pollution and low cost. During the leaching process, the evolution of the pore structure of sandstone-type uranium deposits directly affects the seepage of the leaching solution and the leaching and migration of uranium. However, in-depth research on the leaching characteristics and pore evolution of sandstone-type uranium deposits during the CO_2+O₂ in-situ leaching uranium mining process is of great significance for optimizing the leaching process and improving the uranium leaching rate. Therefore, in-depth research on the leaching characteristics and pore evolution of sandstone-type uranium deposits during the CO_2+O₂ in-situ leaching uranium mining process is of great significance for optimizing the leaching process and improving the uranium leaching rate. Taking a certain sandstone-type uranium deposit in Inner Mongolia as the research object, core samples of uranium-containing sandstone and groundwater samples were systematically collected. Using a self-made in-situ leaching uranium mining simulation experimental device, simulation experiments on the CO_2+O₂ leaching characteristics and pore evolution of core samples of uraniumcontaining sandstone were carried out. Moreover, equipment such as CT scanning was used to characterize the pore structure of core samples of uranium-containing sandstone before and after the experiments. Meanwhile, a threedimensional digital core and pore network model was constructed using Avizo software. The microscopic pore data such as porosity and pore diameter of the core were quantitatively characterized. The research results show that when the volumetric mass ratio of liquid to solid reaches 24.07 mL/g, the uranium leaching rate reaches 64.76%, and the peak uranium concentration in the leaching solution reaches 18.47 mg/L. In the early and middle stages of the leaching experiment, the concentration of HCO₃~– in the leaching solution plays a dominant role in the uranium concentration. When the concentration of HCO₃~– is not less than 800 mg/L, the uranium leaching effect is relatively ideal. The porosity of uranium-containing sandstone cores increases from 12.5% before the experiment to 14.4% after the experiment, and the total porosity drops by 13%. The number of macroporous pores(D_eq≥ 300 μm) and mesopores(150 ≤D_eq<300 μm) decrease significantly, being 0.40 times and 0.55 times that of before the experiment, respectively. This experiment studies the leaching performance of the ore in this deposit by the CO_2+O₂ leaching process, related process parameters, and the pore evolution characteristics of uranium-containing sandstone cores before and after the experiment, providing relevant reference data for CO_2+O₂ in-situ leaching uranium mining and having guiding significance for optimizing the uranium mining process.