Reasonable control of the leaching range is one of the critical indicators of the in-situ leaching uranium mining process. However, there is currently no mature control technology. To verify and improve the current control technology of the leaching range in the industry, this work proposes an injection control mode for a small flow around the well-site and establishes a hydrodynamic model of the leaching range under eight different pumping and injection conditions by using the groundwater modeling system (GMS). The model calculation, range prediction, comparative analysis, and on-site SO₄²⁻ and S isotope verification tests were carried out. Results show that with the change of liquid injection ratio, the area ratios of fixed pumping injection ratio (total pumping flowrate is greater than 0.3% of the total injection flowrate) and model leaching range under four pumping injection equilibrium conditions were 99.10%, 99.99%, 98.30%, and 97.95%, respectively. The farthest migration distance ratios of the leaching solution were 99.37%, 100%, 98.02%, and 97.58%, respectively. It is considered that the operation mode with a fixed pumping injection ratio has no noticeable control effect on the leaching range; selecting a reasonable proportion to regulate the flowrate of injection wells at different positions can effectively reduce the area of the groundwater flow field and realize the effective control of the leaching range. The research results are conducive to saving a lot of evaporation pool construction, land acquisition, human and material resource investment, and environmental policy pressure.

In situ leaching (ISL) uranium mining technology is an in situ mining technology in which the chemical solution is injected into the ore-bearing strata through drilling wells, and the solution moves along the ore bed by controlling the hydraulic gradient of the flow field and reacts with the ore to form uranium-bearing solution. To reduce leaching dead angle in the process of leaching, each pumping and injection unit should achieve uniform leaching at the end of production, and appropriate pumping and injection mode should be adopted for pumping and injection wells of each unit in the mining area. In this paper, on the basis of the actual production data of a sandstone uranium mine, we established the unit flow model of ISL uranium mining area by using GMS software. The unit flow balance of 72 boreholes in the whole mining area was analyzed and optimized through the model. The concept of flow microbalance of pumping and injection unit in the mining area is put forward for the first time, and the calculation equation of supply and receive the flow of pumping and injection well is determined. The calculation and analysis process of flow microbalance of pumping and injection unit in mining area is established. The simulation results showed that the application effect of the model was good, and the correlation coefficient of the solute transport model reached 0.8.

This paper aims to quantitatively analyze the influence of natural groundwater flowing into the flow field of in situ leaching mining. The computational method was built to evaluate the effect of natural groundwater on the production efficiency of pumping wells for the in situ leaching of uranium, and the “flow ratio of groundwater” and related formulas were defined. C1 and C2 mining areas of an in situ leaching uranium mine in Inner Mongolia were taken as an example, and the effect on the “flow ratio of groundwater” when changing the flow quantity of injection wells and the position and length of the filter in the pumping and injection wells were compared. The results show that the variation in the “flow ratio of groundwater” of a whole mining area or a single pumping well in different production stages can be obtained by the neutral solution concentration value from the mining area’s numerical simulation. Regulating the position, length of the filter, and mode of fluid injection in an in situ leaching mine can control the quantity of natural groundwater flowing into the mining area and reduce the fluid exchange between the flow field of in situ leaching uranium mining and natural groundwater.

Based on simulated groundwater streamlines, researchers have developed a theoretical framework for calculating the characteristic volume of in-situ uranium leaching, encompassing both the convection volume and potential leaching volume. This framework was further enhanced by integrating it with the optimization theory of particle release. Through extensive research utilizing the genetic algorithm, a multi-objective optimization program for the flow field of in-situ uranium leaching named MOFISL was created. Consequently, an optimization system combining particle release optimization theory and MOFISL was established. Implementing the optimization system at a specific site in Bayan-Uul. We first determine the most effective method for positioning particles in the given area. Subsequently, the focus of MOFISL was directed towards optimizing the pumping volume while simultaneously minimizing external influence on the flow field, resulting in a series of Pareto optimal solutions. The results indicate that potential leaching volume is primarily influenced by the number of particles released horizontally, with minimal impact from the vertical release. While comparing edge and corner injection wells to internal injection wells, it is notable that internal injection wells have a more complex local flow field. This complexity necessitates a higher quantity of particles for accurate potential leaching volume calculations. By adjusting the weight of optimal solutions, multi-objective optimization management model for in-situ leaching of uranium offers efficient and accurate optimization methods for the decision-making process. The demonstrated adaptability and potential for future enhancements highlight the versatility of the optimization system.