A simulation device for CO2 and O2 fracturing of uranium ore under true triaxial loading conditions

Abstract

The utility model discloses a kind of uranium ore CO2 and O2 fracturing simulation devices under true triaxial loading condition.The device includes pressure chamber, triaxial loading system, CO2 and O2 injection system and uranium ion detection component.Pressure chamber is equipped with water medium for dissolving uranium ion, integrated heating device and water pressure detection sensor.Triaxial loading system is arranged in pressure chamber, and three directions stress is applied.Sample bottom is equipped with fracturing high-pressure pipe to communicate fracturing hole.CO2 and O2 injection system realizes CO2 gaseous fracturing, gaseous and liquid phase change fracturing and supercritical fracturing by high-pressure gas cylinder and pressure control unit.The utility model can simulate real formation environment, analyze CO2 fracturing and O2 leaching mechanism, improve uranium ion dissolution efficiency, reduce environmental pollution, and is suitable for low-permeability uranium mining research.

Description

Technical Field

[0001] This utility model belongs to the field of uranium mining technology, specifically relating to a device for simulating the CO2 and O2 fracturing process of uranium ore under true triaxial loading conditions, used to analyze the fracturing mechanism and uranium ion dissolution efficiency of uranium ore. Background Technology

[0002] Uranium mining, a crucial link in the nuclear fuel industry chain, has a long history of technological development and continuous evolution. As early as the beginning of the 20th century, uranium mining was primarily conducted through traditional open-pit and underground methods, relying on mechanical excavation and blasting techniques to extract ore directly from the ground. According to a report by the World Nuclear Association, uranium mining takes place in approximately 20 countries worldwide, with over 55% of production in 2022 coming from just 10 mines, mainly located in countries such as Kazakhstan, Canada, and Australia. While these traditional methods are efficient, they present significant environmental and safety challenges. For example, open-pit mining leads to large-scale land disturbance, dust pollution, and exposure to radioactive waste, while underground mining faces the risk of collapse and high maintenance costs. With increasing environmental awareness and the demand for developing low-grade uranium resources, in-situ leaching (ISL) technology has gradually become the mainstream method, particularly suitable for sandstone-type uranium deposits.

[0003] The basic principle of ISL (Injection Leaching) technology is to inject a leaching solution into the formation through drilling, dissolving uranium minerals into ionic form, and then recovering the solution through extraction wells. This method avoids large-scale mining, reducing surface disturbance and waste generation. According to data from the U.S. Nuclear Regulatory Commission (NRC) and the International Atomic Energy Agency (IAEA), ISL has become the main source of global uranium production, particularly in Kazakhstan, where it accounts for over 70% of production. ISL can be divided into acid leaching and alkaline leaching. Acid leaching uses acids such as sulfuric acid, which can efficiently dissolve uranium ore, but may lead to groundwater acidification and the risk of heavy metal migration, such as the release of elements like iron and manganese. Alkaline leaching uses sodium bicarbonate or ammonia, suitable for deposits with high carbonate content, but it is less efficient and more expensive. The IAEA's "Uranium Extraction Technology" handbook states that acidic ISL has historically become the mainstream, but the need for environmental remediation is prompting research into more sustainable alternatives.

[0004] In recent years, neutral leaching technology, especially the CO2+O2 leaching system, has attracted much attention. This method utilizes CO2 as an acidifying agent and O2 as an oxidizing agent to achieve in-situ leaching of uranium ore. After CO2 is injected, it reacts with water to form carbonic acid, which promotes the dissolution of uranium minerals (such as hexavalent uranium in uranium ore), while O2 oxidizes tetravalent uranium into easily soluble hexavalent uranium. However, existing CO2+O2 leaching technology still faces challenges, such as insufficient ore permeability leading to uneven distribution of the leachate, and slow oxidation reaction rates affecting efficiency.

[0005] To improve the permeability of ore formations, fracturing technology has been introduced into the field of uranium mining. Traditional hydraulic fracturing uses high-pressure water or chemical agents to create fractures, but it has a significant environmental impact. CO2 fracturing, as an emerging waterless fracturing technology, combined with vibration-assisted CO2+O2 leaching, can improve the uranium leaching efficiency of low-permeability sandstone, but laboratory simulation verification is lacking.

[0006] Existing simulation devices primarily focus on single conditions, such as simple fracturing or leaching simulations, failing to reproduce the real underground environment. True triaxial loading simulation is crucial for simulating multi-directional stress states in formations. Traditional devices, such as rock mechanics testing instruments, can apply triaxial stress but lack integration with CO2 phase modulation, aqueous leaching, and real-time monitoring. In the literature, true triaxial testing is frequently used for stress path analysis in carbonate rocks (e.g., the 2016 study by Ma and Haimson), but it does not incorporate the CO2+O2 system. Existing ISL simulations often neglect the effects of temperature; the underground geothermal gradient (0℃-100℃) is critical to the reaction rate. Furthermore, the lack of aqueous pressure monitoring prevents assessment of the impact of fracturing on groundwater dynamics. Uranium ion detection typically relies on offline analysis, lacking integration with real-time colorimetric sensors.

[0007] These limitations make it difficult for existing technologies to comprehensively analyze the fracturing mechanism of CO2-fracturing uranium ore and the leaching mechanism of different CO2+O2 contents. Environmentally, traditional methods generate serious radioactive waste (such as tailings), and the U.S. Environmental Protection Agency (EPA) reports that uranium mining waste can cause excessive radioactivity in soil and water. Remediation technologies include scraping, sandblasting, and washing, but these are costly. The IAEA's "Environmental Remediation of Uranium Production Facilities" emphasizes the need for innovative simulation devices to assess the environmental impact of new technologies. Overall, while existing uranium mining technologies are mature, their efficiency, environmental friendliness, and simulation accuracy are insufficient. There is an urgent need for a device integrating true triaxial loading, CO2 phase fracturing, O2-assisted leaching, temperature control, and real-time monitoring to simulate the entire process and optimize parameters. This utility model addresses these issues by providing an efficient and environmentally friendly simulation solution. Utility Model Content

[0008] In view of this, the purpose of this utility model is to overcome the shortcomings of the prior art and provide a simulation device for CO2 and O2 fracturing of uranium ore under true triaxial loading conditions, which can simulate the CO2 phase fracturing and O2 leaching process under real formation stress, temperature and water medium environment, and analyze the fracturing mechanism and uranium ion leaching efficiency.

[0009] To achieve the above objectives, this utility model provides the following technical solution:

[0010] A simulation device for CO2 and O2 fracturing of uranium ore under true triaxial loading conditions includes:

[0011] A pressure chamber is used to contain a uranium ore sample and is filled with an aqueous medium, which is used to dissolve uranium ions from the uranium ore sample. The pressure chamber is equipped with a heating device to simulate the temperature environment of the uranium ore sample and change the CO2 phase, as well as a water pressure detection sensor to monitor the pressure changes of the aqueous medium.

[0012] A triaxial loading system, located in the pressure chamber, is used to apply stress in three directions to the uranium ore sample to simulate the formation stress state.

[0013] The bottom of the uranium ore sample is equipped with a high-pressure fracturing pipe, and fracturing holes are drilled on the uranium ore sample. The high-pressure fracturing pipe is connected to the fracturing holes.

[0014] The CO2 and O2 injection system includes a high-pressure O2 cylinder, a high-pressure CO2 cylinder, a pressurization device, and a pressure control unit. The high-pressure CO2 cylinder is connected to the fracturing high-pressure pipe via the pressurization device and pressure control unit, and is used to inject gaseous CO2 into the uranium ore sample to fracture the uranium ore sample. The high-pressure O2 cylinder is connected to the fracturing high-pressure pipe, and is used to inject O2 into the uranium ore sample to promote leaching.

[0015] A uranium ion detection component, located in the pressure chamber, is used to monitor the concentration of uranium ions in the water medium.

[0016] Furthermore, the pressure chamber is a high-pressure resistant vessel capable of withstanding an internal pressure of at least 10 MPa, and is equipped with a liquid injection port to introduce and control the volume of the water medium.

[0017] Furthermore, the water medium is deionized water, and the amount is sufficient to submerge the uranium ore sample, and the pressure chamber includes a water circulation or discharge interface to manage the water medium after leaching.

[0018] Furthermore, the triaxial loading system includes at least three independent actuators fixed to the inner wall of the pressure chamber, which apply force in different directions, with a maximum loading capacity of at least 1000kN in each direction.

[0019] Furthermore, the triaxial loading system also includes a pressure plate, with each actuator connected to a pressure plate. The pressure plate has water immersion holes and directly contacts the uranium ore sample. The actuator achieves stress loading through hydraulic or mechanical drive.

[0020] Furthermore, the fracturing orifice includes a sealing section and a fracturing section, wherein the sealing section is sealed with a sealing material to control the diffusion path of CO2 and O2.

[0021] Furthermore, the uranium ion detection component includes a colorimetric sensor that detects the uranium ion concentration by measuring the color change of the aqueous medium.

[0022] Furthermore, it also includes a sample fixing assembly located in the pressure chamber, which is used to position the uranium ore sample and ensure a sealed connection between the fracturing high-pressure pipe and the fracturing hole.

[0023] The method for conducting experiments using this simulation device includes the following steps:

[0024] S1. Prepare a uranium ore sample and drill a fracturing hole in the sample. The fracturing hole is connected to the fracturing high-pressure pipe at the bottom of the sample.

[0025] S2. Place the uranium ore sample in a pressure chamber and introduce an aqueous medium to immerse the sample, the aqueous medium being used to dissolve uranium ions from the uranium ore sample;

[0026] S3. The internal temperature of the pressure chamber is regulated by a heating device to simulate the ambient temperature of uranium ore and change the CO2 phase state; stress in three directions is applied to the uranium ore sample by a triaxial loading system located in the pressure chamber.

[0027] S4. CO2 and O2 are injected into the fracturing high-pressure pipe through the CO2 and O2 injection system, with the amount of CO2 injected being more than twice that of O2, and the CO2 injection pressure is adjusted in stages through the pressure control unit.

[0028] S5. Without damaging the uranium ore sample, allow CO2 and O2 to leach the uranium ore for a period of time and monitor the changes in the uranium ion sensor.

[0029] S6. Increase the CO2 injection pressure to induce fracturing of the sample, and continue to monitor the changes in uranium ion concentration and water pressure in the water medium after the fracturing.

[0030] In step S6, the following fracturing modes are achieved by changing the water medium temperature and CO2 injection pressure:

[0031] a) Inject gaseous CO2 at a pressure below 7.38 MPa under normal temperature conditions to induce gaseous fracturing;

[0032] b) Under normal temperature conditions, the pressure is controlled within the range of 7.38 MPa to 20 MPa to induce the phase transition of CO2 from gaseous to liquid state, thereby achieving gaseous to liquid phase change fracturing;

[0033] c) Supercritical CO2 is injected under conditions of pressure above 7.38 MPa and temperature above 31.04 °C to achieve supercritical fracturing;

[0034] By monitoring temperature, pressure, water pressure, and uranium ion concentration in the water medium at different stages, the effects of gas fracturing, phase change fracturing, and supercritical fracturing on improving uranium ion dissolution efficiency and permeability were compared.

[0035] The beneficial effects of this utility model are as follows:

[0036] Compared with the prior art, this utility model has the following significant advantages:

[0037] 1. Realistic Formation Environment Simulation: This invention, by setting up a triaxial loading system in a pressure chamber, directly applies stress in the X, Y, and Z directions (maximum loading capacity ≥1000kN in each direction), accurately simulating the real underground stress state. Combined with a heating device to regulate the temperature from 0℃ to 100℃, simulating the geothermal gradient, it overcomes the limitation of existing devices that cannot simultaneously simulate multi-directional stress and temperature conditions. This thermo-mechanical coupling simulation provides a reliable platform for analyzing the fracture and leaching behavior of uranium ore in real formations, helping to reveal the impact of stress-temperature interaction on permeability and leaching rate.

[0038] 2. Realization of Multiphase CO2 Fracturing: The CO2 and O2 injection system, through a pressurization device and pressure control unit, adjusts the CO2 injection pressure in stages to achieve gaseous fracturing (<7.38 MPa, room temperature), gaseous-liquid phase change fracturing (7.38 MPa-50 MPa, room temperature), and supercritical fracturing (>7.38 MPa, >31.1℃). Gaseous fracturing utilizes the expansion force of CO2 to generate fractures; phase change fracturing utilizes volume changes to enhance fracture propagation; supercritical fracturing utilizes the high solubility, high permeability, and low viscosity of CO2 to penetrate deep into micropores. Compared with traditional hydraulic fracturing, CO2 fracturing reduces the use of chemical agents, lowers the risk of groundwater pollution, and simultaneously sequesters a large amount of CO2, mitigating the greenhouse effect. Experiments show that supercritical fracturing can increase the permeability of uranium ore by more than 100 times, significantly improving the leaching rate of low-permeability ore layers.

[0039] 3. High-efficiency uranium ion leaching and real-time monitoring: The pressure chamber contains deionized water, CO2, and O2, immersing the uranium ore sample to promote uranium ion leaching. The uranium ion detection component uses a colorimetric sensor to monitor the uranium ion concentration in the water medium in real time, overcoming the timeliness limitations of traditional offline analysis. A water pressure sensor monitors changes in the water medium pressure, reflecting the impact of fracturing on groundwater dynamics. The combination of these two methods enables dynamic evaluation of leaching efficiency before and after fracturing. Experimental data can be used to optimize the CO2 to O2 injection ratio (CO2 content more than twice that of O2) to improve the leaching rate.

[0040] 4. Environmental Protection and Sustainable Development: This invention employs neutral CO2+O2 leaching, which reduces acidic wastewater discharge compared to acidic leaching, thus lowering the risks of groundwater acidification and heavy metal migration. The sealing design of the fracturing high-pressure pipe and fracturing hole (using epoxy resin in the sealing section) ensures precise gas injection, reduces leakage, and meets environmental protection requirements. Simulation results can guide on-site ISL process optimization, reduce radioactive waste generation, and lower environmental remediation costs (such as the EPA's estimated cost of millions of US dollars per hectare).

[0041] 5. Integrated Structure and Convenient Operation: The pressure chamber integrates a triaxial loading system, heating device, water pressure sensor, and uranium ion detection component, featuring a compact structure and easy operation. The sample fixing assembly and pressure plate (with immersion holes) ensure sample stability and stress transfer efficiency. The pressure control unit achieves automated pressure adjustment via valves or programmed control, improving experimental repeatability and accuracy.

[0042] 6. Wide Applicability: This device is not only suitable for uranium mines, but can also be extended to the simulation of fracturing and leaching of other low-permeability minerals (such as shale, tight sandstone, and coal). The phased monitoring of experimental methods (temperature, pressure, water pressure, and uranium ion concentration) provides a general framework for process optimization for different mineral types.

[0043] In summary, this invention significantly improves the realism, efficiency, and environmental friendliness of uranium ore fracturing and leaching simulation by integrating multifunctional components and systematic experimental methods, providing a scientific basis and technical support for low-permeability uranium ore mining.

[0044] Other advantages, objectives, and features of this invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination and study, or may be learned from practice of this invention. The objectives and other advantages of this invention can be realized and obtained through the following description. Attached Figure Description

[0045] To make the objectives, technical solutions, and advantages of this utility model clearer, the preferred embodiments of this utility model will be described in detail below with reference to the accompanying drawings, wherein:

[0046] Figure 1 This is a schematic diagram of the uranium ore CO2 and O2 fracturing simulation device under true triaxial loading conditions in this utility model.

[0047] Figure 2 for Figure 1 A cross-sectional schematic diagram.

[0048] Reference numerals: 1-Pressure chamber; 2-Loading actuator; 3-Uranium ore sample; 4-Fracturing high-pressure pipe; 5-CO2 gas booster pump; 6-High-pressure O2 cylinder; 7-High-pressure CO2 cylinder; 8-Uranium ion sensor; 9-Water pressure sensor; 10-Hydraulic pump; 11-Pressure plate. Detailed Implementation

[0049] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this utility model. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0050] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the present invention. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0051] In the accompanying drawings of this utility model, the same or similar reference numerals correspond to the same or similar components. In the description of this utility model, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting this utility model. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0052] Example 1

[0053] Please see Figures 1-2This is a simulation device for CO2 and O2 fracturing of uranium ore under true triaxial loading conditions, including a pressure chamber 1, a loading actuator 2 (forming a triaxial loading system), a uranium ore sample 3, a fracturing high-pressure pipe 4, a CO2 gas booster pump 5, a high-pressure O2 gas cylinder 6, a high-pressure CO2 gas cylinder 7, a uranium ion sensor 8, a water pressure sensor 9, a hydraulic pump 10, and a pressure plate 11.

[0054] Pressure chamber 1 is a rectangular, corrosion-resistant, and high-pressure-resistant vessel, measuring 60cm × 60cm × 80cm with a wall thickness of 8cm, designed to withstand a maximum internal pressure of 10MPa. Pressure chamber 1 contains deionized water and CO2 and O2, sufficient to immerse uranium ore sample 3 for dissolving uranium ions from the sample. Pressure chamber 1 integrates an electric heating device with a temperature control range of 0℃-100℃, simulating the underground geothermal environment and simultaneously altering the CO2 phase. A water pressure sensor 9 is installed at the bottom of pressure chamber 1 to monitor pressure changes in the water medium in real time during fracturing and leaching, outputting data to assess the impact of fracturing on hydrodynamics. Pressure chamber 1 is equipped with a liquid injection port and a discharge port for introducing and discharging the water medium, ensuring proper management of the water medium after leaching.

[0055] The triaxial loading system is located inside the pressure chamber 1 and consists of three loading actuators 2, which are fixed to the inner wall of the pressure chamber 1 along the X, Y, and Z directions, respectively. Each loading actuator 2 is driven by a hydraulic pump 10, with a maximum loading capacity of 1000kN, capable of applying multi-directional stress to simulate the stress state of real formations. Each loading actuator 2 is connected to a pressure plate 11, which directly contacts the uranium ore sample 3. The pressure plate has several tiny water immersion holes, allowing water to penetrate into the sample 3, ensuring stress transfer while maintaining a water environment.

[0056] Uranium ore sample 3 is machined into a cuboid with dimensions of 20cm × 20cm × 40cm and an end face flatness of less than 0.02mm. A high-pressure fracturing pipe 4 is installed at the bottom of the sample, connecting to a fracturing hole drilled in the sample. The fracturing hole has a diameter of 3cm and a depth of 30cm, divided into a 10cm sealing section and a 20cm fracturing section. The sealing section is sealed with epoxy resin and a curing agent to control the diffusion paths of CO2 and O2. The sample fixing assembly is located inside the pressure chamber 1 to ensure stable positioning of the uranium ore sample 3 and to guarantee a sealed connection between the high-pressure fracturing pipe 4 and the fracturing hole.

[0057] The CO2 and O2 injection system includes a high-pressure CO2 cylinder 7, a high-pressure O2 cylinder 6, a CO2 gas booster pump 5, and a pressure control unit. The high-pressure CO2 cylinder 7 is connected to the fracturing high-pressure tubing 4 via the CO2 gas booster pump 5 and the pressure control unit, with a maximum injection pressure of 70 MPa. The pressure control unit adjusts the CO2 injection pressure in stages through valves and programmed control to achieve the following fracturing modes:

[0058] Gas fracturing: Under normal temperature conditions and pressures below 7.38 MPa, gaseous CO2 is injected to induce fracture formation by utilizing the gas expansion force.

[0059] Gas-liquid phase change fracturing: Under normal temperature conditions, the pressure is controlled within the range of 7.38MPa-50MPa to induce the conversion of CO2 between gaseous and liquid states, and the volume expansion due to the phase change is used to enhance fracture propagation.

[0060] Supercritical fracturing: Supercritical CO2 is injected under conditions of pressure above 7.38 MPa and temperature above 31.04 °C in pressure chamber 1. Its low viscosity, high solubility and high permeability are utilized to penetrate deep into the micropores of the sample, thereby improving fracturing efficiency.

[0061] O2 is injected into uranium ore sample 3 through high-pressure O2 cylinder 6 via high-pressure fracturing pipe 4. The amount of O2 injected is controlled to be less than 1 / 2 of that of CO2, which promotes the oxidation of tetravalent uranium to easily soluble hexavalent uranium and optimizes the leaching rate.

[0062] Uranium ion sensor 8 is a colorimetric sensor located in pressure chamber 1. It monitors the color change of the water medium in real time to detect the uranium ion concentration, providing dynamic data of the leaching process. Water pressure sensor 9 works in conjunction with the data acquisition interface to record changes in water medium pressure. Combined with the data from uranium ion sensor 8, the fracturing damage and leaching effect of specimen 3 are evaluated.

[0063] Example 2

[0064] This embodiment, based on the apparatus of Embodiment 1, provides a method for simulating CO2 and O2 fracturing of uranium ore under true triaxial loading conditions. The specific steps are as follows:

[0065] S1: Sample preparation

[0066] Process uranium ore samples to a size of 3-20cm × 20cm × 40cm, with an end face flatness of less than 0.02mm. Drill fracturing holes with a diameter of 3cm and a depth of 30cm into the samples, dividing them into a 10cm sealing section and a 20cm fracturing section. The sealing section is sealed with epoxy resin and a curing agent. Install a high-pressure fracturing pipe 4 at the bottom of the sample, ensuring communication with the fracturing holes.

[0067] S2: Sample installation and water medium injection

[0068] Place the uranium ore sample 3 in the sample fixing assembly inside the pressure chamber 1, ensuring a sealed connection between the fracturing high-pressure pipe 4 and the fracturing hole. Introduce deionized water medium through the liquid injection port of the pressure chamber 1 to immerse the uranium ore sample 3 for uranium ion dissolution. Tighten the bolts of the pressure chamber 1 and check for airtightness.

[0069] S3: Temperature and Stress Control

[0070] The temperature is controlled between 0℃ and 100℃ using an electric heating device within pressure chamber 1 to simulate the underground geothermal environment and simultaneously alter the CO2 phase. A triaxial loading system (including loading actuator 2 and hydraulic pump 10) located within pressure chamber 1 applies stress in the X, Y, and Z directions to the uranium ore sample 3, gradually loading it to simulate formation stress levels (≥1000kN per direction). Several tiny water-immersing holes on the pressure plate 11 ensure contact between the water medium and the sample.

[0071] S4: Gas Injection and Pressure Control

[0072] Open high-pressure CO2 cylinder 7 and high-pressure O2 cylinder 6, and inject CO2 and O2 into the fracturing high-pressure pipe 4 through CO2 gas booster pump 5 and pressure control unit. The CO2 content is controlled to be more than twice that of O2. The pressure control unit adjusts the CO2 injection pressure in stages.

[0073] At room temperature, gaseous CO2 is injected at a pressure below 7.38 MPa to induce gaseous fracturing;

[0074] Under normal temperature conditions, the pressure is controlled within the range of 7.38MPa-50MPa to induce the phase transition of CO2 from gaseous to liquid state, thereby achieving gaseous-liquid phase change fracturing.

[0075] Supercritical fracturing is achieved by injecting supercritical CO2 under conditions of pressure above 7.38 MPa and temperature above 31.04 °C.

[0076] S5: Monitoring of the leaching process

[0077] Without damaging uranium ore sample 3, the well was kept sealed for 10 days with CO2 and O2 present in an aqueous medium. The uranium ion concentration in the aqueous medium was monitored by uranium ion sensor 8, and the leaching efficiency was recorded. Water pressure sensor 9 monitored the pressure changes in the aqueous medium in real time to analyze whether sample 3 was damaged by CO2 fracturing and the impact on hydrodynamics.

[0078] S6: Fracturing Failure and Subsequent Monitoring

[0079] The CO2 injection pressure was increased by a CO2 gas booster pump 5 to induce fracturing in uranium ore sample 3. The well was then kept sealed with CO2 and O2 for 10 days. The uranium ion concentration and water pressure changes in the aqueous medium after fracturing were monitored using a uranium ion sensor 8 and a water pressure sensor 9. Temperature, pressure, water pressure, and uranium ion concentration data were recorded in stages to compare the effects of gas fracturing, gas-liquid phase change fracturing, and supercritical fracturing on improving uranium ion leaching efficiency and permeability.

[0080] Experimental results show that supercritical fracturing increases uranium ion leaching rate by about 20% compared to gas fracturing, gas-liquid phase change fracturing increases it by about 12%, and CO2 fracturing increases uranium ore permeability by more than 100 times, providing data support for optimizing CO2+O2 in-situ leaching process.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of this technical solution, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A simulation device for CO2 and O2 fracturing of uranium ore under true triaxial loading conditions, characterized in that, include: A pressure chamber is used to contain a uranium ore sample and is filled with an aqueous medium, which is used to dissolve uranium ions from the uranium ore sample. The pressure chamber integrates a heating device to simulate the temperature environment of the uranium ore sample and change the phase state of CO2, as well as a water pressure detection sensor to monitor the pressure changes of the aqueous medium. A triaxial loading system, located in the pressure chamber, is used to apply stress in three directions to the uranium ore sample to simulate the formation stress state. The bottom of the uranium ore sample is equipped with a high-pressure fracturing pipe, and fracturing holes are drilled on the uranium ore sample. The high-pressure fracturing pipe is connected to the fracturing holes. The CO2 and O2 injection system includes a high-pressure O2 cylinder, a high-pressure CO2 cylinder, a pressurization device, and a pressure control unit. The high-pressure CO2 cylinder is connected to the fracturing high-pressure pipe via the pressurization device and pressure control unit, and is used to inject gaseous CO2 into the uranium ore sample to fracture the uranium ore sample. The high-pressure O2 cylinder is connected to the fracturing high-pressure pipe, and is used to inject O2 into the uranium ore sample to promote leaching. A uranium ion detection component, located in the pressure chamber, is used to monitor the concentration of uranium ions in the water medium.

2. The simulation device according to claim 1, characterized in that, The pressure chamber is a corrosion-resistant and high-pressure-resistant vessel capable of withstanding an internal pressure of at least 10 MPa, and is equipped with a liquid injection port to introduce and control the volume of the water medium.

3. The simulation device according to claim 1, characterized in that, The water medium is deionized water, and the amount is sufficient to submerge the uranium ore sample. The pressure chamber includes a water circulation or discharge port to manage the water medium after leaching.

4. The simulation device according to claim 1, characterized in that, The triaxial loading system includes at least three independent actuators fixed to the inner wall of the pressure chamber, which apply force in different directions, with a maximum loading capacity of at least 1000kN in each direction.

5. The simulation device according to claim 4, characterized in that, The triaxial loading system also includes a pressure plate, with each actuator connected to a pressure plate. The pressure plate has several water immersion holes and directly contacts the uranium ore sample. The actuator achieves stress loading through hydraulic or mechanical drive.

6. The simulation device according to claim 1, characterized in that, The fracturing orifice includes a sealing section and a fracturing section. The sealing section is sealed with a sealing material to control the diffusion path of CO2 and O2.

7. The simulation device according to claim 1, characterized in that, The uranium ion detection component includes a colorimetric sensor that detects the uranium ion concentration by measuring the color change of the aqueous medium.

8. The simulation device according to claim 1, characterized in that, It also includes a sample fixing assembly, which is located in the pressure chamber and is used to position the uranium ore sample and ensure a sealed connection between the fracturing high-pressure pipe and the fracturing hole.

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