Uranium mine in-situ leaching mining multi-field coupling simulation method, device, equipment and medium

Abstract

The invention discloses a uranium ore in-situ leaching mining multi-field coupling simulation method, device, equipment and medium, and relates to the field of in-situ leaching uranium mining. According to the uranium mine in-situ leaching mining multi-field coupling simulation method, the device, the equipment and the medium, in-situ leaching uranium mining reactive solute transport control of sandstone type uranium mine reservoir stress-seepage-chemical action is considered, and the influence of fluid temperature in the uranium mine reservoir and reservoir damage in the in-situ leaching process on in-situ leaching mining is emphatically considered; a distribution function is adopted to represent heterogeneity of mechanical parameters, so that a seepage-chemical-temperature-damage full-coupling numerical model suitable for sandstone type uranium mine CO2 and O2 in-situ leaching is established, and leachate uranium concentration data obtained through simulation calculation is compared with uranium concentration data of an on-site leaching test; the full-coupling numerical model is optimized to obtain a reasonable mathematical model to predict the parameter change trend in the CO2 and O2 in-situ leaching uranium mining process, and important guiding significance is provided for optimization of site scale CO2 and O2 in-situ leaching mining.

Description

Technical Field

[0001] This application relates to the field of in-situ leaching uranium mining, and more specifically, to a simulation method, apparatus, equipment, and medium for multi-field coupling in in-situ leaching uranium mining. Background Technology

[0002] In-situ leaching (ISL) is a key technology for producing natural uranium. This method integrates mining, beneficiation, and smelting, offering advantages such as low mining costs, high resource utilization, and minimal environmental pollution. It has become the primary method for natural uranium production both domestically and internationally, accounting for over 90% of total natural uranium production capacity. CO2 and O2 neutral in-situ leaching technologies effectively address engineering challenges in sandstone-type uranium deposits, such as low permeability, long leaching cycles, uneven extraction and injection, and easy clogging of ore layers. Large-scale industrial applications have been achieved in the Ordos, Songliao, Ili, and Turpan-Hami basins in northern my country.

[0003] However, the CO2 and O2 in-situ leaching process for uranium involves the dynamic processes of fluid flow within the rock (porous space) due to seepage dynamics, reservoir damage and changes in physical properties caused by the interaction between groundwater and reservoir rock, solute diffusion and migration, and the extraction of uranium-containing leachate. Currently, there is no relatively mature reaction transport simulation technology.

[0004] Although some research has been conducted on uranium extraction and solute transport processes through in-situ leaching, it has mainly focused on geochemical simulations, groundwater dynamic field simulations, and fully coupled calculations of hydrodynamic and chemical dynamic processes. However, it has not considered the heterogeneity of reservoir physical properties or the influence of reservoir temperature. Furthermore, damage to the reservoir during pressurized injection of in-situ leaching fluid can also affect numerical simulations, leading to significant discrepancies between the conclusions drawn and actual field conditions.

[0005] Therefore, a simulation method and apparatus for multi-field coupling in uranium leaching mining is needed to quantitatively analyze and characterize the effects of different factors on uranium leaching performance. Summary of the Invention

[0006] The purpose of this application is to provide a simulation method, apparatus, equipment and medium for multi-field coupling in uranium leaching mining. It optimizes and predicts the parameter change trends during CO2 and O2 in-situ leaching uranium mining by establishing a fully coupled numerical model of seepage-chemistry-temperature-damage suitable for sandstone-type uranium ore, and provides important guidance for optimizing CO2 and O2 in-situ leaching mining at the site scale.

[0007] This application is implemented as follows: This application provides a simulation method for multi-field coupling in uranium leaching mining, comprising the following steps: S1. Collect geological structure and in-situ leaching mining data for uranium deposits; S2. Based on the geological structure and in-situ leaching mining data, construct a geometric model characterizing the heterogeneity of mechanical parameters based on field test conditions; S3. Construct the seepage field, solute transport field, temperature field, and damage field of the leachate during the uranium leaching process, respectively. S4. Establish a mathematical model for multi-field coupling of CO2 and O2 in-situ uranium leaching. S5. Determine the constraints of the mathematical model for the multi-field coupling of CO2 and O2 in uranium leaching, perform spatial grid partitioning and time discretization of the model, and calculate the uranium concentration data of the leachate in numerical simulation. S6. Compare the uranium concentration data from the on-site leaching test with the uranium concentration data from the numerical simulation of the leaching solution. If the error does not meet the requirements, return to step S2 until the error meets the requirements and a reasonable mathematical model is obtained. S7. Based on a reasonable mathematical model, obtain the parameter variation trends during CO2 and O2 uranium leaching processes, and evaluate the influence of component indicators on the reaction and migration of uranium during CO2 and O2 uranium leaching processes.

[0008] In some alternative implementations, the geological structure and in-situ leaching data of the uranium ore include mineral composition, uranium ore composition, location of injection wells, injection volume, and hydrochemical data of the leaching solution and leachate.

[0009] In some alternative implementations, the mechanical parameters include elastic modulus, uniaxial compressive strength, Poisson's ratio, and coefficient of thermal expansion.

[0010] In some alternative implementations, the following distribution function is used to construct a geometric model characterizing the non-homogeneity of the mechanical parameters: ; In the formula, ω These are the mechanical parameters of the uranium ore layer; ω 0 represents the average mechanical parameters of the uranium ore layer; The uniformity index of the distribution function is denoted by . The smaller the value, the stronger the heterogeneity of the uranium ore layer.

[0011] In some alternative implementations, when constructing the seepage field, solute transport field, temperature field, and damage field of the leachate during uranium leaching, the tensile and shear damage of the uranium ore layer in the damage field are calculated using the following formulas: ; ; In the formula, and are the threshold functions for tensile failure and shear failure of uranium ore layers, respectively, where tensile force is positive and compressive force is negative; For the maximum principal stress, It is the minimum principal stress; and These are the uniaxial tensile and compressive strengths of the rock mass, respectively. This represents the internal friction angle.

[0012] In some alternative implementations, when constructing the seepage field, solute transport field, temperature field, and damage field of the leachate during uranium leaching, the following formula is used to characterize the multi-component solute transport in the seepage field: ; ; In the formula, Porosity of porous media; The concentration of each solute component is given in mol / m³. 3 ; Fluid density, kg / m³ 3 ; Indicates the calculation time, in days; J The flux of the solute; Darcy convection velocity; For convection terms; For the reaction source term, it refers to the change in solute concentration in the pores caused by the chemical reaction, expressed in mol / (L·s); m is the effective diffusion coefficient of each solute component. 2 / s; subscript Indicates different components.

[0013] In some alternative implementations, when constructing the seepage field, solute transport field, temperature field, and damage field of the leachate during uranium leaching, the following formula is used to characterize the heat exchange between geological bodies and the cooling process of the entire system in the temperature field: ; ; ; ; ; In the formula, Temperature, °C; To simplify the thickness of the geological geometry model, m; For fluid density; Specific heat capacity of hydrothermal fluid, J / (kg·K); Indicates the calculation time, in days; The fluid velocity is in m / s; Let J be the heat conduction flux. The total heat inflow is expressed in J. The total heat of reaction is J; J represents the heat exchange rate between the model and its surrounding environment. Density of porous media (sandstone, mudstone, or coal seam), kg / m³ 3 ; This refers to the change in pore size in porous media. Porosity of porous media; is the specific heat capacity of the porous medium containing hydrothermal fluid, J / (kg·K); is the thermal conductivity of the porous medium, W / (m·K); is the thermal conductivity of the hydrothermal fluid, W / (m·K); The effective thermal conductivity is W / (m·K); is the ambient thermal conductivity, W / (m·K).

[0014] In some alternative implementations, when constructing the seepage field, solute transport field, temperature field, and damage field of the leachate during uranium leaching, the following formula is used to characterize the reaction rates of mineral dissolution and precipitation in the solute transport field: ; In the formula, Let be the dissolution / precipitation rate of the i-th mineral, mol / (m 3 ·s); The reaction rate constant is controlled by temperature and acid-base mechanisms, in mol / (m 3 ·s); The reactive surface area per kilogram of water, in cm² 2 / g; χ represents mineral saturation; χ and η are empirical parameters from experimental data, generally taken as 1.

[0015] In some alternative implementations, the reaction rate constant under temperature and acid-base mechanism control is calculated using the following formula. : ; In the formula, The kinetic reaction rate constant is given at 25℃, in mol / (m²). 2 ·s); The activation energy of the reaction is expressed in kJ / mol. This represents the activation energy of the reaction under a neutral mechanism. This is the activation energy of the reaction under acidic conditions. This is the activation energy of the reaction under alkaline conditions. The gas constant is 8.314 kJ / mol·K; K represents the reaction temperature; nu is a constant under neutral conditions. n H This is a constant under acidic conditions.n OH This is a constant under the alkaline mechanism; a H and a OH These are the ionic activities of hydrogen ions and hydroxide ions, respectively.

[0016] In some alternative implementations, the trends in the parameters include the leaching concentration of dissolved uranium (VI), the pH value of the in-situ leaching well solution, and the trends in the concentration of major minerals in the in-situ leaching well solution.

[0017] In some alternative implementations, the component parameters include porosity, permeability, volume content, and elastic modulus.

[0018] This application also provides a simulation device for multi-field coupling in uranium leaching mining, including: The data acquisition module is used to collect data on the geological structure and in-situ leaching mining of uranium deposits. The geometric model building module is used to construct a geometric model characterizing the heterogeneity of mechanical parameters based on the geological structure and in-situ leaching mining data of uranium ore collected by the acquisition module and the field test conditions. The field construction module is used to construct a description of the seepage field, solute transport field, temperature field, and damage field of the leachate during the uranium ore leaching process based on the geological structure and in-situ leaching mining data of the uranium ore collected by the acquisition module. The coupling module is used to construct a mathematical model of multi-field coupling of CO2 and O2 in-situ uranium mining based on the field construction module to describe the seepage field, solute transport field, temperature field and damage field of the leachate during uranium leaching. The simulation module is used for spatial grid partitioning and temporal discretization of the mathematical model of multi-field coupling of CO2 and O2 in-situ uranium leaching, based on input constraints. The calculation module is used to calculate the uranium concentration data of the leachate from the CO2 and O2 uranium leaching multi-field coupling mathematical model based on the spatial grid partitioning and time discretization processing of the simulation module. The judgment module compares the uranium concentration data from the input field leaching test with the uranium concentration data from the numerical simulation calculated by the calculation module, and outputs a reasonable mathematical model whose error meets the requirements. The results processing module is used to calculate the parameter variation trends during CO2 and O2 uranium leaching based on the reasonable mathematical model.

[0019] This application also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above-described method.

[0020] This application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0021] The beneficial effects of this application are as follows: The simulation method, apparatus, equipment, and medium for multi-field coupling in-situ leaching mining of uranium provided in this application, by considering the stress-seepage-chemical effects of sandstone-type uranium reservoirs and the control of reactive solute transport in in-situ leaching mining, focuses on the influence of fluid temperature in the uranium reservoir and reservoir damage during in-situ leaching on in-situ leaching mining, and uses a distribution function to characterize the heterogeneity of mechanical parameters. Thus, a fully coupled numerical model suitable for seepage-chemistry-temperature-damage in-situ leaching of CO2 and O2 in sandstone-type uranium mines is established. The uranium concentration data of the leaching solution obtained by simulation calculation is compared with the uranium concentration data of the field leaching test. The fully coupled numerical model is optimized to obtain a reasonable mathematical model to predict the parameter change trend during CO2 and O2 in-situ leaching mining, which provides important guidance for the optimization of site-scale CO2 and O2 in-situ leaching mining. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A schematic flowchart illustrating the multi-field coupling simulation method for uranium leaching mining provided in this application embodiment; Figure 2 The parameters for CO2 and O2 in-situ leaching of uranium in sandstone-type uranium deposits in the study area were obtained in the simulation method for multi-field coupling of in-situ leaching mining of uranium provided in Embodiment 1 of this application. Figure 3 In the simulation method for multi-field coupling of uranium leaching mining provided in Embodiment 1 of this application, a geometric model is constructed to simulate the distribution image of the elastic modulus of the target layer sandstone of a uranium deposit in Xinjiang when m=8 based on the distribution function; Figure 4 The main chemical reactions and thermodynamic data of uranium in groundwater used in the multi-field coupling simulation method for uranium leaching mining provided in Embodiment 1 of this application; Figure 5 The initial concentration and pH value of the chemical components of the groundwater in the uranium ore-bearing leaching mining simulation method provided in Example 1 of this application are used to reflect the uranium ore-bearing ore layer. Figure 6 The reaction kinetic rate parameters of four minerals modeled during the CO2 and O2 leaching process in the simulation method of multi-field coupling for uranium ore in-situ leaching mining provided in Embodiment 1 of this application; Figure 7 In the simulation method for multi-field coupling of uranium leaching mining provided in Embodiment 1 of this application, the pore water pressure distribution change trend during CO2 and O2 uranium leaching mining is obtained based on a reasonable mathematical model; Figure 8 In the simulation method for multi-field coupling of uranium leaching mining provided in Embodiment 1 of this application, the trend of uranium concentration change during CO2 and O2 uranium leaching mining is obtained based on a reasonable mathematical model; Figure 9 In the simulation method for multi-field coupling of uranium leaching mining provided in Embodiment 1 of this application, the trend of uranium concentration change over time during CO2 and O2 leaching uranium mining is obtained based on a reasonable mathematical model; Figure 10 The simulation method for multi-field coupling of uranium leaching mining provided in Embodiment 1 of this application obtains the trend of oxygen concentration change over time during CO2 and O2 uranium leaching mining based on a reasonable mathematical model; Figure 11 The simulation method for multi-field coupling of uranium leaching mining provided in Embodiment 1 of this application obtains the trend of HCO3- concentration changing with time during CO2 and O2 uranium leaching mining based on a reasonable mathematical model; Figure 12 This is a schematic diagram of an embodiment of the computer device structure provided in Embodiment 2 of this application. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0025] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0026] The following detailed description, in conjunction with embodiments, further illustrates the characteristics and performance of the simulation method, apparatus, equipment, and medium for multi-field coupling in uranium leaching mining according to this application.

[0027] like Figure 1 As shown in the figure, this application provides a simulation method for multi-field coupling in uranium leaching mining, including the following steps: S1. Clarify the geological background and mining status of sandstone-type uranium deposits in the study area, and collect geological structure and in-situ leaching mining data of uranium deposits; among which, the geological structure and in-situ leaching mining data of uranium deposits include mineral composition, uranium ore composition, location of injection wells, injection volume, and hydrochemical data of leaching solution and leachate.

[0028] S2. Based on geological structure and in-situ leaching mining data, construct a geometric model characterizing the heterogeneity of mechanical parameters based on field test conditions; among which, mechanical parameters include elastic modulus, uniaxial compressive strength, Poisson's ratio, and coefficient of thermal expansion.

[0029] When constructing a geometric model characterizing the non-homogeneity of mechanical parameters, the following distribution function is used: ; In the formula, ω These are the mechanical parameters of the uranium ore layer; ω 0 represents the average mechanical parameters of the uranium ore layer; The uniformity index of the distribution function is denoted by . The smaller the value, the stronger the heterogeneity of the uranium ore layer.

[0030] S3. Based on the COMSOL Multiphysics module, construct the seepage field, solute transport field, temperature field and damage field of the leachate during the leaching process of sandstone-type uranium ore. 3.1 Using the maximum tensile stress criterion and the Moore-Coulomb criterion, the following formulas are established to calculate the tensile and shear damage of the uranium ore layer in the damage field: ; ; In the formula, and These are the threshold functions for tensile failure and shear failure of uranium ore layers, respectively. To ensure consistency with the stress sign law in numerical calculations, the stress sign law of mechanics of materials is adopted, with tensile force being positive and compressive force being negative. For the maximum principal stress, It is the minimum principal stress; and These are the uniaxial tensile and compressive strengths of the rock mass, respectively. This represents the internal friction angle.

[0031] When calculating the damage to the uranium ore layer in the damage field, tensile damage is prioritized over shear damage under any stress condition.

[0032] 3.2. Based on PHREEQC calculations, the geochemical reactions during CO2 and O2 uranium leaching are as follows: ; ; ; ; ; The thermodynamic database for CO2 and O2 leaching processes in sandstone-type uranium deposits uses data from Qiu Wenjie et al. (2022), and the reaction rate equations involved in mineral dissolution and precipitation are determined based on the chemical reaction kinetic transition state theory (TST).

[0033] 3.3 The following formula is used to characterize the multi-component solute transport in the seepage field: ; ; In the formula, Porosity of porous media; The concentration of each solute component is given in mol / m³. 3 ; Fluid density, kg / m³ 3 ; Indicates the calculation time, in days; J The flux of the solute; Darcy convection velocity; For convection terms; For the reaction source term, it refers to the change in solute concentration in the pores caused by the chemical reaction, expressed in mol / (L·s); m is the effective diffusion coefficient of each solute component. 2 / s; subscript Indicates different components.

[0034] 3.4 The following formula is used to characterize the heat exchange between geological bodies in the temperature field and the cooling process of the entire system: ; ; ; ; ; In the formula, Temperature, °C; To simplify the thickness of the geological geometry model, m; For fluid density; Specific heat capacity of hydrothermal fluid, J / (kg·K); Indicates the calculation time, in days; The fluid velocity is in m / s; Let J be the heat conduction flux. The total heat inflow is expressed in J. The total heat of reaction is J; J represents the heat exchange rate between the model and its surrounding environment. Density of porous media (sandstone, mudstone, or coal seam), kg / m³ 3 ; This refers to the change in pore size in porous media. Porosity of porous media; is the specific heat capacity of the porous medium containing hydrothermal fluid, J / (kg·K); is the thermal conductivity of the porous medium, W / (m·K); is the thermal conductivity of the hydrothermal fluid, W / (m·K); The effective thermal conductivity is W / (m·K); is the ambient thermal conductivity, W / (m·K).

[0035] The following formula is used to characterize the reaction rates of mineral dissolution and precipitation in a solute transport field: ; In the formula, Let be the dissolution / precipitation rate of the i-th mineral, mol / (m 3 ·s); The reaction rate constant is controlled by temperature and acid-base mechanisms, in mol / (m 3 ·s); The reactive surface area per kilogram of water, in cm² 2 / g; χ represents mineral saturation; χ and η are empirical parameters from experimental data, generally taken as 1.

[0036] The reaction rate constant under temperature and acid-base mechanism control is calculated using the following formula. : ; In the formula, The kinetic reaction rate constant is given at 25℃, in mol / (m²). 2 ·s); The activation energy of the reaction is expressed in kJ / mol. This represents the activation energy of the reaction under a neutral mechanism. This is the activation energy of the reaction under acidic conditions. This is the activation energy of the reaction under alkaline conditions. The gas constant is 8.314 kJ / mol·K; K represents the reaction temperature; nu is a constant under neutral conditions. n H This is a constant under acidic conditions. n OHThis is a constant under the alkaline mechanism; a H and a OH These are the ionic activities of hydrogen ions and hydroxide ions, respectively.

[0037] S4. Establish a mathematical model for multi-field coupling of CO2 and O2 in-situ leaching uranium. The mathematical model for multi-field coupling of CO2 and O2 in-situ leaching uranium is based on the site scale. According to the field test conditions of in-situ leaching mining, construct in-situ leaching units such as "four injections and one extraction" or "six injections and two extractions" and "six injections and one extraction" formed by four injection wells and one extraction well.

[0038] S5. Determine the constraints of the mathematical model for the multi-field coupling of CO2 and O2 in uranium leaching, perform spatial grid partitioning and time discretization of the model, and calculate the uranium concentration data of the leachate in numerical simulation; among which, the constraints include initial conditions, boundary conditions, and source and sink terms.

[0039] S6. Compare the uranium concentration data from the on-site leaching test with the uranium concentration data from the numerical simulation of the leaching solution. If the error does not meet the requirements, return to step S2 until the error meets the requirements and a reasonable mathematical model is obtained. S7. Based on a reasonable mathematical model, obtain the parameter variation trends during CO2 and O2 uranium leaching processes, and evaluate the influence of component indicators on the reaction and migration of uranium during CO2 and O2 uranium leaching processes.

[0040] The parameter trends include the leaching concentration of dissolved uranium (VI), the pH value of the in-situ leaching well solution, and the trends in the concentration of major minerals in the in-situ leaching well solution. Component indicators include porosity, permeability, volume content, and elastic modulus.

[0041] This application also provides a simulation device for multi-field coupling in uranium leaching mining, including: The data acquisition module is used to collect data on the geological structure and in-situ leaching mining of uranium deposits. The geometric model building module is used to construct a geometric model characterizing the heterogeneity of mechanical parameters based on the geological structure and in-situ leaching mining data of uranium ore collected by the acquisition module and the field test conditions. The field construction module is used to construct a description of the seepage field, solute transport field, temperature field, and damage field of the leachate during the uranium ore leaching process based on the geological structure and in-situ leaching mining data of the uranium ore collected by the acquisition module. The coupling module is used to construct a mathematical model of multi-field coupling of CO2 and O2 in-situ uranium mining based on the field construction module to describe the seepage field, solute transport field, temperature field and damage field of the leachate during uranium leaching. The simulation module is used for spatial grid partitioning and temporal discretization of the mathematical model of multi-field coupling of CO2 and O2 in-situ uranium leaching, based on input constraints. The calculation module is used to calculate the uranium concentration data of the leachate from the CO2 and O2 uranium leaching multi-field coupling mathematical model based on the spatial grid partitioning and time discretization processing of the simulation module. The judgment module compares the uranium concentration data from the input field leaching test with the uranium concentration data from the numerical simulation calculated by the calculation module, and outputs a reasonable mathematical model whose error meets the requirements. The results processing module is used to calculate the parameter variation trends during CO2 and O2 uranium leaching based on the reasonable mathematical model.

[0042] The simulation device and method for multi-field coupling of uranium leaching mining provided in this application considers the reactive solute transport control of uranium leaching in sandstone-type uranium ore reservoir stress-seepage-chemical effects. It focuses on the influence of fluid temperature in the uranium reservoir and reservoir damage during leaching on leaching mining, and uses a distribution function to characterize the heterogeneity of mechanical parameters. Thus, a fully coupled numerical model suitable for seepage-chemistry-temperature-damage in CO2 and O2 leaching of sandstone-type uranium ore is established. The simulation calculation of uranium concentration data in the leaching solution is compared with the uranium concentration data from the field leaching test. The fully coupled numerical model is optimized to obtain a reasonable mathematical model to predict the parameter change trend during CO2 and O2 uranium leaching mining, which provides important guidance for optimizing CO2 and O2 in-situ leaching mining at the site scale.

[0043] Example 1 This application provides a simulation method for multi-field coupling in uranium leaching mining, comprising the following steps: S1. Clarify the geological background and mining status of sandstone-type uranium deposits in the study area, and collect data on the geological structure and in-situ leaching mining of uranium deposits; The uranium deposit is hosted in the upper sub-section of the first lithological section of the Xishanyao Formation (J2x). 1Within the sand bodies, the ore-bearing sand bodies gradually deepen from east to west and from south to north. The main ore layer is buried at a depth of 110.0–140.0 m, with a thickness generally ranging from 1.55–10.95 m (average thickness 3.37 m) and a grade of 0.0174%–0.0825% (average grade 0.0345%). The lithology of the ore-bearing target layer is mainly composed of gray fine sandstone, gray medium sandstone, yellow medium sandstone, and yellow sandstone series. The framework particles of the ore-bearing sand bodies are mainly composed of quartz (20–32% by mass), feldspar (10–15% by mass), and rock fragments (47–75% by mass); the interstitial material is mostly argillaceous matrix and clay minerals, with calcite cement visible locally. Adsorbed uranium in the ore body is mainly hosted in clay minerals, pyrite, and carbonaceous fragments, while uranium minerals are mainly pitchblende and uranium ore.

[0044] The ore-bearing and water-bearing strata in the mining area are located in the third lithological section of the Xishanyao Formation (J2x). 3 The aquifer contains confined aquifer water with a thickness ranging from 7.2 to 56.0 m, averaging 26.3 m. The thickness is relatively stable, with a coefficient of variation of 36.0%. A continuous 47.5-hour hydrological test using a constant flow rate of "1 pumping and 4 injections" revealed a permeability coefficient of 0.40 m / d and a hydraulic conductivity of 5.81 m. 2 / d.

[0045] S2. Based on geological structure and in-situ leaching mining data, construct a geometric model to characterize the heterogeneity of mechanical parameters based on field test conditions; The simulated stratigraphic position is the upper sub-section of the first lithological section of the Xishanyao Formation (J2x). 1 This study focuses on the complex processes of reservoir deformation, fluid flow, and chemical reaction coupling during CO2 and O2 in-situ leaching of uranium. Based on the injection and extraction well configuration in the mining area, a "1-injection-4-extraction" model consisting of four injection wells and one extraction well is adopted. A two-dimensional model (52m x 52m) is extracted from the geological model of the mining area as the research object, where the straight-line distance between injection wells is 40m and the straight-line distance between extraction and injection wells is 29m.

[0046] Coupled calculations were performed using the multiphysics simulation software COMSOL. The ore-bearing medium was assumed to be a continuous, relatively homogeneous porous medium. Seepage and chemical kinetic calculations were performed on this model, and the uranium leaching performance was quantitatively analyzed. Based on the field test conditions, a "1 extraction, 4 injection" mode was adopted. The physical parameters used in the mathematical simulation were obtained based on collected CO2 and O2 in-situ leaching data from the study area; see details below. Figure 2 .

[0047] Secondly, based on the field test conditions, a geometric model was constructed, and the non-homogeneity of the mechanical parameters such as elastic modulus, uniaxial compressive strength, Poisson's ratio, and coefficient of thermal expansion was characterized by the Weibull distribution function. The specific expressions are as follows: ; In the formula, ω These are the mechanical parameters (such as elastic modulus or strength) of the uranium ore layer; ω 0 represents the average value of the mechanical parameters; is the uniformity index of the Weibull distribution function; The smaller the value, the stronger the heterogeneity of the uranium ore layer. Figure 3 The Weibull distribution of the elastic modulus of the target layer sandstone in a uranium deposit in Xinjiang is shown when m=8, which can effectively characterize the heterogeneity of the uranium ore layer.

[0048] S3. Based on the COMSOL Multiphysics module, construct the seepage field, solute transport field, temperature field and damage field of the leachate during the leaching process of sandstone-type uranium ore. The maximum tensile stress criterion and the Moore-Coulomb criterion are used to determine the damage degree of the uranium ore layer. When the stress state of the rock mass (compression is positive) satisfies the above criteria, the tensile damage and shear damage of the uranium ore layer are respectively: ; ; In the formula, and These are the threshold functions for judging tensile failure and shear failure, respectively; it should be noted that tensile damage is always the first to be judged under any stress condition. For the maximum principal stress, The minimum principal stress is used; to ensure consistency with the stress sign rules of numerical calculation software, the stress sign rules of mechanics of materials are adopted, with tensile force being positive and compressive force being negative. and These represent the uniaxial tensile and compressive strengths of trace elements in coal, respectively. This represents the internal friction angle.

[0049] The main ionic components of the leachate and groundwater were selected as the primary input variables for the reactive solute transport model, including Na. + Ca 2+ Al 3+ H + K + HCO 3- CO2, O2, SiO2 (ag), AlO 2-U(VI), its associated aqueous complexes and equilibrium constants are defined in the thermodynamic database as follows: Figure 4 As shown. The initial ore-bearing groundwater chemical composition and pH values ​​used in the reactive solute transport model are shown in [reference needed]. Figure 5 The temperature was 25℃. Based on the mineral characteristics analysis of the study area, the mineral components involved in the geochemical reaction mainly included quartz, albite, potassium feldspar, muscovite, calcite, and pitchblende. The adsorption of hexavalent uranium (U(VI)) by iron oxides and clay minerals in the aquifer was ignored.

[0050] Based on the actual conditions of in-situ leaching uranium mining projects in the study area, oxygen (O2) and carbon dioxide (CO2) were continuously injected into the ore-bearing aquifer during the simulation. In the PHREEQC simulation, the chemical reaction rate expressions for CO2, O2, and uranium ore were set as follows: ; In the formula, Let be the dissolution / precipitation rate of the i-th mineral, mol / (m 3 ·s); The reaction rate constant is controlled by temperature and acid-base mechanisms, in mol / (m 3 ·s); The reactive surface area per kilogram of water, in cm² 2 / g; χ represents mineral saturation; χ and η are empirical parameters from experimental data, generally taken as 1.

[0051] According to the Arrhenius equation, the reaction rate constant at 25°C... for: ; In the formula, The kinetic reaction rate constant is given at 25℃, in mol / (m²). 2 ·s); The activation energy of the reaction is expressed in kJ / mol. This represents the activation energy of the reaction under a neutral mechanism. This is the activation energy of the reaction under acidic conditions. This is the activation energy of the reaction under alkaline conditions. The gas constant is 8.314 kJ / mol·K; K represents the reaction temperature; nu is a constant under neutral conditions. n H This is a constant under acidic conditions. n OH This is a constant under the alkaline mechanism; a H and a OHThese are the ionic activities of hydrogen ions and hydroxide ions, respectively.

[0052] The main mechanism of CO2 and O2 in-situ leaching for uranium extraction involves injecting a leaching agent prepared with CO2 and O2 into the uranium-bearing ore layer. O2 oxidizes the uranium ore (UO2) in the ore layer into hexavalent uranium (U(VI)), which then dissolves in the leaching solution. CO2 gas dissolves in water to form carbonic acid, which then decomposes to generate bicarbonate. This provides coordinating ions for uranium complexation. The interaction between the leaching solution and the ore body during in-situ uranium mining mainly includes the convection and hydrodynamic dispersion of the main components (including dissolved uranium) in groundwater. The chemical reaction network includes water-rock interactions such as oxidation-reduction, dissolution-precipitation, complexation-dissociation, and adsorption-desorption between the leaching agent and the uranium ore and surrounding rock. The main chemical reactions involved are detailed in [link to relevant documentation]. Figure 4 The listed reactions and values ​​are from the Ilnl.dat database and the ThermoChimie thermodynamics database: Studies have shown that the oxidative dissolution of uranium ore (UO2) is a multi-step chemical reaction process, consisting of five steps: 1. The leaching agent diffuses from the bulk solution to the ore surface; 2. The leaching agent is adsorbed onto the ore surface; 3. The leaching agent adsorbed on the inner surface of the ore reacts chemically with the ore; 4. The reaction products desorb from the ore surface; 5. The products diffuse away from the ore surface. This invention, based on a review of relevant literature, Figure 6 The reaction kinetic rates of four minerals frequently involved in geochemical modeling of CO2 and O2 leaching processes are listed. ),activation energy( Specific surface area ( ), equilibrium constant ( ) and other parameters. In the figure, (a) is the dissolution rate constant of the mineral under the neutral mechanism; (b) is the dissolution rate constant of the mineral under the acidic mechanism; (c) is the precipitation rate constant of the mineral.

[0053] S4. Establish a mathematical model for the multi-field coupling of CO2 and O2 in-situ leaching of uranium; the multi-physics coupling mathematical simulation is solved by Darcy's law, rare matter transport, solid mechanics, porous media heat transfer module and domain ordinary differential and differential algebraic equations in COMSOL Multiphysics, and realizes the coupling simulation of COMSOL fluid transport and PHREEQC geochemical reaction based on the interface program developed by MATLAB.

[0054] S5. Determine the constraints of the mathematical model for the multi-field coupling of CO2 and O2 in uranium leaching, perform spatial grid partitioning and time discretization of the model, and calculate the uranium concentration data of the leachate in numerical simulation. The multiphysics model was meshed using free triangles, with mesh refinement around the extraction and injection holes. The model was divided into 19,812 triangular elements, 40 edge elements, and 35 vertex elements. This meshing met the accuracy requirements of this simulation.

[0055] S6. Compare the uranium concentration data from the on-site leaching test with the uranium concentration data from the numerical simulation of the leaching solution. If the error does not meet the requirements, return to step S2 until the error meets the requirements and a reasonable mathematical model is obtained. S7. Based on a reasonable mathematical model, obtain the parameter variation trends during CO2 and O2 uranium leaching processes, and evaluate the influence of component indicators on the reaction and migration of uranium during CO2 and O2 uranium leaching processes.

[0056] Figure 7 The distribution of pore water pressure during the immersion process shows that the water pressure around the injection well is relatively high, while the water pressure around the pumping well is relatively low. The water pressure around the pumping well gradually increases outward along the well diameter. Figure 8 UO2(CO3)2 2- Concentration transport distribution cloud map, Figure 9 The graph shows the change in uranium leaching concentration over time. It can be seen that the uranium leaching concentration increased rapidly in the first 50 days, from 0.001 mol / m³. 3 Increased to 0.023 mol / m 3 However, it gradually stabilized after 100 days, reaching approximately 0.025 mol / m 3 Furthermore, based on the main chemical reactions of uranium in groundwater, the leaching concentration of uranium is mainly affected by the concentration of dissolved oxygen and HCO3-. 3- It changes with the concentration.

[0057] Figure 10 and Figure 11 Dissolved oxygen concentration and HCO3- concentration, respectively 3- The graph shows the concentration changes over time. It can be seen that as the CO2 and O2 leaching process continues, the dissolved oxygen [O2(aq)] concentration and HCO3- concentration decrease. 3- The concentrations all decreased to varying degrees, which is opposite to the trend of uranium mass concentration change; this is because the dissolution reaction of the original uranium consumed dissolved oxygen [O2(aq)] and HCO3- concentration. 3- The concentration of uranium also reacted with other minerals, such as calcite (CaCO3). The results of indoor column tests by Wu Jianfeng et al. (2021) also confirmed that the peak of uranium concentration was also accompanied by the addition of higher oxygen [O2(aq)], which indicates that sufficient oxygen is crucial for the leaching effect of uranium during in-situ leaching.

[0058] Example 2 like Figure 12As shown, this embodiment provides a simulation computer device (801) for multi-field coupling in uranium leaching mining, which may include: a processor (802) and a memory (803) of one or more computer-readable storage media. The simulation computer device may also include one or more of the following: a multimedia component (804), an I / O interface (805), a communication component (806), a power supply (807), an input unit (808), and an output unit (809). Those skilled in the art will understand that... Figure 12 The computer device structure shown does not constitute a limitation on the computer device and may include more or fewer components than shown, or combine certain components, or have different component arrangements. Wherein: The processor (802) is the control center of the computing device, used to control the overall operation of the simulation computer device (801) for multi-field coupling of uranium leaching mining, to complete all or part of the steps in the above-described simulation method for multi-field coupling of sandstone-type uranium leaching mining. Preferably, the processor (802) may include one or more processing cores. The memory (803) is used to store various types of data to support the operation of the simulation computer device (801) for multi-field coupling of uranium leaching mining. This data may include, for example, instructions for any application or method operating on the simulation computer device (801) for multi-field coupling of uranium leaching mining, as well as application-related data (sending and receiving messages, pictures, audio, video, etc.). The memory (803) can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), Flash Memory, magnetic disk or optical disk, etc. The multimedia component (804) may include a screen and an audio component. The screen may be a touchscreen, and the audio component is used to output and / or input audio signals. The received audio signals may be further stored in the memory (803) or transmitted via a communication component (806). The audio component also includes at least one speaker for outputting audio signals. The I / O interface (805) provides an interface between the processor (802) and other interface modules, such as a keyboard, mouse, buttons, etc. The communication component (806) enables wired or wireless communication between the analog computer device (801) used for multi-field coupling in sandstone-type uranium leaching mining and other devices. Wireless communication includes Wi-Fi, Bluetooth, Near Field Communication (NFC), 2G, 3G, or 4G, or a combination thereof.The power supply (807) mainly supplies power to the various components of the analog computer equipment (801) for multi-field coupling in uranium leaching mining. The power supply (807) can be logically connected to the processor (802) through the power management storage medium, thereby realizing the functions of managing charging, discharging, and power consumption management through the power management storage medium. The power supply (807) may also include one or more DC or AC power supplies, recharge storage medium, power fault detection circuit, power converter or inverter, power status indicator, and other arbitrary components.

[0059] The analog computer device (801) for multi-field coupling in-situ leaching mining of uranium mines may further include an input unit (808) and an output unit (809). The input unit (808) can be used to receive input digital or character information and generate keyboard, mouse, joystick, optical, or trackball signal inputs related to user settings and function control. The output unit (809) can be used to export output digital or character information and generate keyboard, mouse, joystick, optical, or trackball signal inputs related to user settings and function control. In addition, the analog computer device (801) for multi-field coupling in-situ leaching mining of uranium mines may also include a display unit, etc., which will not be described in detail here. Specifically, in this embodiment, the processor (802) in the computer device will load the executable files corresponding to the processes of one or more application programs into the memory (803) according to the following instructions, and the processor (802) will run the application programs stored in the memory (803) to realize the steps in the above method embodiment.

[0060] Example 3 This embodiment also provides a readable storage medium for simulating multi-field coupling in-situ leaching mining of uranium deposits. The readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the simulation method for multi-field coupling in-situ leaching mining of sandstone-type uranium deposits described above. This readable storage medium includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps described in the various embodiments of this invention. Therefore, the beneficial effects achievable by any method provided in the embodiments of this application can be realized, as detailed in the preceding embodiments, and will not be repeated here.

[0061] The readable storage medium specifically includes: USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks or optical disks, and other media that can store program code.

[0062] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A simulation method for multi-field coupling in uranium leaching mining, characterized in that, Includes the following steps: S1. Collect geological structure and in-situ leaching mining data for uranium deposits; S2. Based on the geological structure and in-situ leaching mining data, construct a geometric model characterizing the heterogeneity of mechanical parameters based on field test conditions; S3. Construct the seepage field, solute transport field, temperature field, and damage field of the leachate during the uranium leaching process, respectively. S4. Establish a mathematical model for multi-field coupling of CO2 and O2 in-situ uranium leaching. S5. Determine the constraints of the mathematical model for the multi-field coupling of CO2 and O2 in uranium leaching, perform spatial grid partitioning and time discretization of the model, and calculate the uranium concentration data of the leachate in numerical simulation. S6. Compare the uranium concentration data from the on-site leaching test with the uranium concentration data from the numerical simulation of the leaching solution. If the error does not meet the requirements, return to step S2 until the error meets the requirements and a reasonable mathematical model is obtained. S7. Based on a reasonable mathematical model, obtain the parameter variation trends during CO2 and O2 uranium leaching processes, and evaluate the influence of component indicators on the reaction and migration of uranium during CO2 and O2 uranium leaching processes.

2. The simulation method for multi-field coupling in uranium leaching mining according to claim 1, characterized in that, The geological structure and in-situ leaching mining data of the uranium mine include mineral composition, uranium ore composition, location of injection wells, injection volume, and hydrochemical data of the leaching solution and leachate.

3. The simulation method for multi-field coupling in uranium leaching mining according to claim 1, characterized in that, The mechanical parameters include elastic modulus, uniaxial compressive strength, Poisson's ratio, and coefficient of thermal expansion.

4. The simulation method for multi-field coupling in uranium leaching mining according to claim 1, characterized in that, The following distribution function is used to construct a geometric model characterizing the non-homogeneity of the mechanical parameters: ； In the formula, ω These are the mechanical parameters of the uranium ore layer; ω 0 represents the average mechanical parameters of the uranium ore layer; The uniformity index of the distribution function is denoted by . The smaller the value, the stronger the heterogeneity of the uranium ore layer.

5. The simulation method for multi-field coupling in uranium leaching mining according to claim 1, characterized in that, When constructing the seepage field, solute transport field, temperature field, and damage field of the leachate during uranium leaching, the following formulas are used to calculate the tensile and shear damage of the uranium ore layer in the damage field: ； ； In the formula, and are the threshold functions for tensile failure and shear failure of uranium ore layers, respectively, where tensile force is positive and compressive force is negative; For the maximum principal stress, It is the minimum principal stress; and These are the uniaxial tensile and compressive strengths of the rock mass, respectively. This represents the internal friction angle.

6. The simulation method for multi-field coupling in uranium leaching mining according to claim 1, characterized in that, When constructing the seepage field, solute transport field, temperature field, and damage field of the leachate during uranium leaching, the following formula is used to characterize the multi-component solute transport in the seepage field: ； ； In the formula, Porosity of porous media; The concentration of each solute component is given in mol / m³. 3 ; Fluid density, kg / m³ 3 ; Indicates the calculation time, in days; J The flux of the solute; Darcy convection velocity; For convection terms; For the reaction source term, it refers to the change in solute concentration in the pores caused by the chemical reaction, expressed in mol / (L·s); m is the effective diffusion coefficient of each solute component. 2 / s; subscript Indicates different components.

7. The simulation method for multi-field coupling in uranium leaching mining according to claim 1, characterized in that, When constructing the seepage field, solute transport field, temperature field, and damage field of the leachate during uranium leaching, the following formula is used to characterize the heat exchange between geological bodies and the cooling process of the entire system in the temperature field: ； ； ； ； ； In the formula, Temperature, °C; To simplify the thickness of the geological geometry model, m; For fluid density; Specific heat capacity of hydrothermal fluid, J / (kg·K); Indicates the calculation time, in days; The fluid velocity is in m / s; Let J be the heat conduction flux. The total heat inflow is expressed in J. The total heat of reaction is J; J represents the heat exchange rate between the model and its surrounding environment. Density of porous media (sandstone, mudstone, or coal seam), kg / m³ 3 ; This refers to the change in pore size in porous media. Porosity of porous media; is the specific heat capacity of the porous medium containing hydrothermal fluid, J / (kg·K); is the thermal conductivity of the porous medium, W / (m·K); is the thermal conductivity of the hydrothermal fluid, W / (m·K); The effective thermal conductivity is W / (m·K); is the ambient thermal conductivity, W / (m·K).

8. The simulation method for multi-field coupling in uranium leaching mining according to claim 1, characterized in that, When constructing the seepage field, solute transport field, temperature field, and damage field of the leachate during uranium leaching, the following formula is used to characterize the reaction rate of mineral dissolution and precipitation in the solute transport field: ； In the formula, Let be the dissolution / precipitation rate of the i-th mineral, mol / (m 3 ·s); The reaction rate constant is controlled by temperature and acid-base mechanisms, in mol / (m 3 ·s); The reactive surface area per kilogram of water, in cm² 2 / g; χ represents mineral saturation; χ and η are empirical parameters from experimental data, generally taken as 1.

9. The simulation method for multi-field coupling in uranium leaching mining according to claim 8, characterized in that, The reaction rate constant under temperature and acid-base mechanism control is calculated using the following formula. : ； In the formula, The kinetic reaction rate constant is given at 25℃, in mol / (m²). 2 ·s); The activation energy of the reaction is expressed in kJ / mol. This represents the activation energy of the reaction under a neutral mechanism. This is the activation energy of the reaction under acidic conditions. This is the activation energy of the reaction under alkaline conditions. The gas constant is 8.314 kJ / mol·K; K represents the reaction temperature; nu is a constant under neutral conditions. n H This is a constant under acidic conditions. n OH This is a constant under the alkaline mechanism; a H and a OH These are the ionic activities of hydrogen ions and hydroxide ions, respectively.

10. The simulation method for multi-field coupling in uranium leaching mining according to claim 1, characterized in that, The trends in these parameters include the leaching concentration of dissolved uranium (VI), the pH value of the leaching well solution, and the trends in the concentration of major minerals in the leaching well solution.

11. The simulation method for multi-field coupling in uranium leaching mining according to claim 1, characterized in that, The component parameters include porosity, permeability, volume content, and elastic modulus.

12. A simulation device for multi-field coupling in uranium leaching mining, characterized in that, include: The data acquisition module is used to collect data on the geological structure and in-situ leaching mining of uranium deposits. The geometric model building module is used to construct a geometric model characterizing the heterogeneity of mechanical parameters based on the geological structure and in-situ leaching mining data of uranium ore collected by the acquisition module and the field test conditions. The field construction module is used to construct a description of the seepage field, solute transport field, temperature field, and damage field of the leachate during the uranium ore leaching process based on the geological structure and in-situ leaching mining data of the uranium ore collected by the acquisition module. The coupling module is used to construct a mathematical model of multi-field coupling of CO2 and O2 in-situ uranium mining based on the field construction module to describe the seepage field, solute transport field, temperature field and damage field of the leachate during uranium leaching. The simulation module is used for spatial grid partitioning and temporal discretization of the mathematical model of multi-field coupling of CO2 and O2 in-situ uranium leaching, based on input constraints. The calculation module is used to calculate the uranium concentration data of the leachate from the CO2 and O2 uranium leaching multi-field coupling mathematical model based on the spatial grid partitioning and time discretization processing of the simulation module. The judgment module compares the uranium concentration data from the input field leaching test with the uranium concentration data from the numerical simulation calculated by the calculation module, and outputs a reasonable mathematical model whose error meets the requirements. The results processing module is used to calculate the parameter variation trends during CO2 and O2 uranium leaching based on the reasonable mathematical model.

13. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the steps of the method according to any one of claims 1 to 11.

14. A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method according to any one of claims 1 to 11.

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