低渗砂岩型铀矿液态CO2相变致裂增透高效开采新模式

安全稳定的铀资源供应，对于保障国家安全、促进核工业健康可持续发展具有重要的意义。针对我国低渗透性砂岩型铀矿在地浸开采中渗透性低、浸出困难的技术难题，提出了低渗砂岩型铀矿液态CO2相 变致裂增透高效开采技术模式，即采用液态CO2相变致裂技术，在地浸采铀抽、注液孔之间产生大量的联通裂隙，提高低渗透铀矿的渗流能力。采用理论方法计算了液态CO2相变致裂影响半径，建立了液态CO2相变致裂 增透地浸开采流程，系统进行了低渗砂岩型铀矿液态CO2相变致裂增透高效开采技术特征研究。结果表明：低渗砂岩型铀矿液态CO2相变致裂增透技术影响半径为6.53 m，该技术能够实现三维应力条件下岩体致裂破坏 ，能够有效增加岩体损伤裂隙网络分布，具有破岩致裂增透、降低化学沉淀及经济可行性。研究结果为有效解决低渗透性造成的砂岩型铀矿地浸开采“难注、难采、低回收率”等难题提供了新途径。

Feasibility Study on Enhanced Permeability of Low Permeability Sandstone Type Uranium Deposit with Liquid CO2 Phase Transition Fracturing

Safe and stable supply of uranium resources is of great significance for ensuring national security and promoting the sustainable and healthy development of the nuclear industry. Aiming at the technical bottleneck of the high-efficiency mining of low-permeability sandstone-type uranium deposits in our country， a technical idea of a low-permeability sandstone-type uranium deposit with liquid CO2 phase transition fracturing and high-efficiency mining method was proposed. That is， the liquid CO2 phase transition fracturing technology was used to generate a large number of interconnected fracture between the in-situ leaching extraction holes and injection holes to improve the seepage capacity of the low-permeability uranium ore. The theoretical method was used to calculate the influence radius of liquid CO2 phase transition fracturing， and the liquid CO2 phase transition fracturing and permeability enhancement in-situ leaching mining process was established. The system carried out a feasibility study on low-permeability sandstone-type uranium deposits with liquid CO2 phase transition fracturing to increase permeability and high-efficiency mining. The results showed that: The influence radius of liquid CO2 phase change fracturing to increase permeability technology was 6.53 m. This technology can achieve rock fracture failure under three-dimensional stress conditions， could effectively increase the distribution of rock damage and fracture network， and has the advantages of rock fracturing， reducing chemical precipitation and economic feasibility. The results of this paper provided a possible way to solve the problem of low permeability and low leaching rate in the process of in-situ leaching of sandstone-type uranium deposits， and would be of great significance to the future breakthrough of the low-permeability sandstone uranium ore problem with low leaching rate.