Method for improving leaching efficiency of in-situ leaching uranium mining based on heating

Abstract

The invention relates to the technical field of neutral in-situ leaching uranium mining, and provides a method for improving in-situ leaching uranium mining efficiency based on heating. The method comprises the following steps: (1) arranging a plurality of electric heating elements and temperature control sensors in an injection well according to injection well parameters and ore body distribution characteristics; (2) preheating the leaching liquid in the injection well to a target temperature by using a plurality of electric heating elements and a temperature control sensor, and keeping the temperature stable; (3) oxygen and carbon dioxide are introduced into the leaching liquid to form a leaching agent, and the leaching agent is injected into the ore-bearing and water-bearing stratum through a liquid injection pipeline for uranium leaching operation; and (4) uranium-containing leachate produced by the ore-containing and water-containing layer is conveyed to ion exchange equipment to be subjected to uranium adsorption treatment, adsorption tail liquid is obtained, and the adsorption tail liquid serves as a part of the leaching liquid and returns to the step (2). The uranium leaching reaction rate is increased by increasing the reaction temperature of a leaching system, the uranium concentration is increased, the leaching process is effectively shortened, and high efficiency and stability are achieved.

Description

Technical Field

[0001] This application relates to the field of neutral leaching uranium technology, and proposes a method for improving the leaching efficiency of uranium in ground leaching based on heating. Background Technology

[0002] Neutral leaching is suitable for sandstone-type uranium deposits with high carbonate content, offering advantages such as low leaching costs and high uranium concentration in the leachate. As a more environmentally friendly uranium mining process compared to acid leaching, neutral leaching has been industrialized in most uranium mines.

[0003] However, neutral leaching of uranium still faces technical bottlenecks in practical applications:

[0004] The reducing components such as pyrite and organic matter that are commonly found in mineral-bearing aquifers compete with hexavalent uranium for oxygen during the leaching process, which severely inhibits the oxidative dissolution of uranium(IV).

[0005] The low-temperature environment downhole leads to slow uranium mineral dissolution kinetics, resulting in a longer overall leaching cycle and lower efficiency.

[0006] Current technologies are unable to solve the above problems, and there is an urgent need to propose a leaching enhancement method that can efficiently promote the reaction and has good engineering applicability, so as to improve the efficiency of central uranium leaching and shorten the leaching cycle. Summary of the Invention

[0007] To address the aforementioned problems, this application provides a method for improving the efficiency of uranium leaching in in-situ leaching based on heating, thereby solving the problem of low uranium leaching rate.

[0008] The technical solution adopted in this application is as follows:

[0009] This application provides a method for improving the efficiency of uranium extraction in in-situ leaching based on heating, the method comprising:

[0010] Step (1): Based on the injection well parameters and ore body distribution characteristics, multiple electric heating elements and temperature control sensors are arranged in the injection well;

[0011] Step (2) involves using multiple electric heating elements and temperature control sensors to preheat the leaching solution injected into the well to the target temperature and maintain it stable.

[0012] Step (3): Oxygen and carbon dioxide are introduced into the leaching solution to form a leaching agent, and the leaching agent is injected into the mineral-bearing aquifer through the injection pipeline for uranium leaching operation;

[0013] Step (4) involves transporting the uranium-containing leachate from the mineralized aquifer to an ion exchange device for uranium adsorption treatment to obtain adsorption tail liquid, which is then returned to step (2) as part of the leaching solution.

[0014] Optionally, in step (1), based on the injection well parameters and ore body distribution characteristics, multiple electric heating elements and temperature control sensors are arranged within the injection well, including:

[0015] The total heating power of a single well is calculated based on the thermal conductivity of the rock strata, the heating area, the density of the leaching solution, the target temperature, the initial temperature, and the preset heating time.

[0016] The number of electric heating elements and the location of each electric heating element are determined based on the total heating power of a single well, the parameters of the mineral-bearing aquifer, and the power of each electric heating element.

[0017] Multiple electric heating elements are arranged according to their quantity and location.

[0018] Optionally, the total heating power of a single well is calculated based on the thermal conductivity of the rock formation, the heating area, the density of the leaching solution, the target temperature, the initial temperature, and the preset heating time, including:

[0019] The total heating power of a single well is determined according to the following formula (1):

[0020] P = k × A × ρ × (T) set -T init ) / t, formula (1);

[0021] Where P represents the total heating power of a single well, k represents the thermal conductivity of the rock formation, A represents the heating area, ρ represents the density of the leaching solution, and T represents the total heating power of a single well. set T represents the target temperature. init t represents the initial temperature, and t represents the preset heating time.

[0022] The number of electric heating elements and the placement of each element are determined based on the total heating power of a single well, the parameters of the mineral-bearing aquifer, and the power of each electric heating element. This includes:

[0023] The number of elements to be arranged is determined based on the total heating power of a single well and the power of each electric heating element.

[0024] Depending on the number of elements to be deployed, the electric heating elements are asymmetrically arranged along the well wall of the injection well in the corresponding area of ​​the mineralized aquifer. Starting from the highest depth of the mineralized aquifer, 2 to 4 electric heating elements are added in the same well section for every 100 meters increase in depth.

[0025] Optionally, the electric heating element is a ceramic electric heating rod.

[0026] Optionally, in step (1), based on the injection well parameters and ore body distribution characteristics, multiple electric heating elements and temperature control sensors are arranged within the injection well, including:

[0027] Temperature sensors are deployed at the highest depth of the mineral-bearing aquifer, the middle depth of the mineral-bearing aquifer, the bottom depth of the mineral-bearing aquifer, and at key nodes through which the leaching agent flows. Each temperature sensor is connected to a temperature field simulation module, which in turn is connected to a feedback control module.

[0028] Optionally, step (2), which involves using multiple electric heating elements and temperature control sensors to preheat the leaching solution in the injection well to the target temperature and maintain it stable, includes:

[0029] Multiple electric heating elements are used to heat the leaching solution in the injection well;

[0030] The temperature field simulation module receives multiple temperature signals from multiple temperature sensors in real time, calculates feedback control signals based on the multiple temperature signals, and transmits them to the feedback control module.

[0031] The feedback control module adjusts the heating status of multiple electric heating elements according to the feedback control signal, so that the leaching solution in the injection well is preheated to the target temperature and maintained stably.

[0032] Optionally, the preheating time is 1 to 3 hours, the target temperature is 35 to 55°C and the temperature fluctuation range does not exceed 2°C.

[0033] Optionally, step (3) involves introducing oxygen and carbon dioxide into the leaching solution to form a leaching agent, and then injecting the leaching agent into the ore-bearing aquifer through an injection pipeline for uranium leaching operations, including:

[0034] Oxygen is introduced into the leaching solution to form a primary leaching agent, which is then injected into the ore-bearing aquifer through an injection pipeline for uranium leaching operations.

[0035] Detect the residual oxygen concentration in uranium-bearing leachate produced from mineral-bearing aquifers;

[0036] When the residual oxygen concentration is greater than 5 mg / L, carbon dioxide is introduced into the primary leaching agent to make the pH value 6.0-7.5 to form a leaching agent. The leaching agent is then injected into the ore-bearing aquifer through the injection pipeline to continue the uranium leaching operation.

[0037] Optionally, the oxygen concentration in the leaching agent is 200–400 mg / L, and the carbon dioxide concentration in the leaching agent is 200–600 mg / L.

[0038] Optionally, in step (4), the uranium-bearing leachate from the mineralized aquifer is transported to an ion exchange device for uranium adsorption treatment to obtain adsorption tailings, which are then returned to step (2) as part of the leaching solution. This includes:

[0039] The uranium-containing leachate from the mineral-bearing aquifer is treated with a strongly alkaline anion exchange resin to obtain the adsorption tailings.

[0040] The adsorption tail liquid is returned to step (2) as part of the leaching solution, wherein the uranium concentration in the adsorption tail liquid is less than 5 mg / L;

[0041] The leaching solution also includes: groundwater containing bicarbonate, wherein the concentration of bicarbonate is not less than 150 mg / L.

[0042] The above-mentioned technical solution adopted in this application can achieve the following beneficial effects:

[0043] The method for improving uranium leaching efficiency through heating proposed in this application can solve the technical problems of slow leaching reaction rate and low uranium concentration in existing central uranium leaching processes. This method significantly increases the uranium leaching reaction rate by raising the reaction temperature of the leaching system, resulting in a uranium concentration increase of over 10%, and significantly improves the oxidative leaching effect of tetravalent uranium in ore. This method effectively shortens the leaching process, and the entire reaction process does not experience blockage of the well site injection fluid, exhibiting both high efficiency and stability. This method is suitable for large-scale neutral leaching uranium mining engineering applications. Attached Figure Description

[0044] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0045] Figure 1 A schematic diagram of a method for improving the efficiency of uranium leaching in in-situ based on heating is shown.

[0046] Figure 2 A process flow diagram is shown for a method to improve the uranium brilliance efficiency of in-situ leaching based on heating;

[0047] Figure 3 The graph shows the change of uranium concentration over time during the indoor leaching process in Example 1.

[0048] Figure 4 The graph shows the change of uranium concentration over time during the field leaching process in Example 1.

[0049] Figure 5 The graph shows the change of uranium concentration over time during the field test leaching process in Example 2. Detailed Implementation

[0050] Exemplary embodiments of this application will now be described in more detail. However, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.

[0051] Figure 1 This diagram illustrates the process flow of the method for improving uranium leaching efficiency in in-situ leaching based on heating, as provided in this application. Please refer to... Figure 1 As shown, the process includes the following steps S101 to S104.

[0052] Step S101: Based on the injection well parameters and ore body distribution characteristics, multiple electric heating elements and temperature control sensors are arranged in the injection well.

[0053] To improve the efficiency of uranium leaching in in-situ leaching, a heating system is first installed. The heating system includes at least multiple electric heating elements and temperature control sensors.

[0054] Multiple electric heating elements are used to heat the leaching solution in the injection well. A temperature control sensor is used to adjust the multiple electric heating elements based on real-time monitored temperature data to maintain the leaching solution in the injection well at the target temperature.

[0055] In some optional implementations, step S101 involves arranging multiple electric heating elements and temperature control sensors within the injection well based on the injection well parameters and ore body distribution characteristics. This includes: calculating the total heating power of a single well based on the thermal conductivity of the rock strata, the heating area, the density of the leaching solution, the target temperature, the initial temperature, and the preset heating time; determining the number of electric heating elements and the placement position of each electric heating element based on the total heating power of the single well, the parameters of the ore-bearing aquifer, and the power of each electric heating element; and arranging the multiple electric heating elements according to the number and placement positions.

[0056] The heating system includes multiple corrosion-resistant electric heating elements arranged in the injection well for heating the leaching solution.

[0057] The number of multiple electric heating elements is determined based on the thermal conductivity of the rock strata, the heating area, the density of the leaching solution, the target temperature, the initial temperature, the preset heating time, and the power of each electric heating element. The placement of each electric heating element is determined based on the number of elements and the parameters of the ore-bearing aquifer.

[0058] Specifically, the total heating power of a single well is determined according to the following formula (1):

[0059] P = k × A × ρ × (T) set -T init ) / t, formula (1);

[0060] Where P represents the total heating power of a single well, k represents the thermal conductivity of the rock formation, A represents the heating area, ρ represents the density of the leaching solution, and T represents the total heating power of a single well. set T represents the target temperature. init t represents the initial temperature, and t represents the preset heating time.

[0061] The number of elements to be arranged is determined based on the total heating power of a single well and the power of each electric heating element.

[0062] In practice, the quantity of items can be determined according to the following formula (2):

[0063] n = P / q, formula (2);

[0064] Where n represents the number of elements arranged, and q represents the power of each electric heating element (each electric heating element has the same power).

[0065] Depending on the number of elements, the electric heating elements are asymmetrically arranged along the well wall in the corresponding region of the mineralized aquifer. This asymmetrical arrangement along the well wall improves thermal convection efficiency.

[0066] Starting from the highest depth of the mineral-bearing aquifer, 2 to 4 electric heating elements are added to the same well section for every 100 meters of depth.

[0067] The density of electric heating elements in the injection well can be increased with the depth of the mineralized aquifer. Specifically, taking the highest depth of the mineralized aquifer as the starting point for burial depth, 2 to 4 electric heating elements are added within the same well section for every 100 meters of burial depth.

[0068] In some alternative implementations, the electric heating element is a ceramic electric heating rod.

[0069] In some optional implementations, step S101 involves arranging multiple electric heating elements and temperature control sensors within the injection well based on the injection well parameters and ore body distribution characteristics. This includes arranging temperature sensors at the highest depth of the ore-bearing aquifer, the middle depth of the ore-bearing aquifer, the bottom depth of the ore-bearing aquifer, and at key nodes through which the leaching agent flows. Each temperature sensor is connected to a temperature field simulation module, and the temperature field simulation module is connected to a feedback control module.

[0070] The heating system also includes a temperature control sensor, which is used to monitor temperature data in real time and dynamically adjust the heating state of the electric heating element based on the temperature data.

[0071] To accurately collect temperature data, the temperature control sensor comprises multiple temperature sensors distributed across the upper, middle, and lower parts of the ore-bearing aquifer, as well as key nodes through which the leaching agent flows. For example, the temperature control sensors can be positioned at the top, middle, and bottom of the ore layer, and downstream of the injection well.

[0072] Specifically, each temperature sensor is connected to a temperature field simulation module, which in turn is connected to a feedback control module.

[0073] The temperature field simulation module establishes the temperature-reaction kinetic relationship based on a multi-physics coupling model, and the feedback control module can dynamically adjust the heating state of the electric heating element.

[0074] Step S102: The leaching solution injected into the well is preheated to the target temperature and kept stable using multiple electric heating elements and temperature control sensors.

[0075] After the heating system is installed, the wiring connections and programming between the heating system and the injection coordination unit of the injection well can be debugged. After debugging, downhole preheating and temperature control can be performed.

[0076] In some optional embodiments, step S102, which uses multiple electric heating elements and temperature control sensors to preheat the leaching solution in the injection well to a target temperature and maintain it stably, includes: heating the leaching solution in the injection well using multiple electric heating elements; the temperature field simulation module receiving multiple temperature signals fed back by multiple temperature sensors in real time, calculating a feedback control signal based on the multiple temperature signals and transmitting it to the feedback control module; and the feedback control module adjusting the heating state of the multiple electric heating elements according to the feedback control signal, so that the leaching solution in the injection well is preheated to the target temperature and maintained stably.

[0077] Multiple electric heating elements are activated to heat the leaching solution in the injection well. If these multiple electric heating elements are not controlled, the temperature of the leaching solution in the injection well will continue to rise; therefore, multiple temperature sensors provide real-time temperature feedback.

[0078] The temperature field simulation module calculates feedback control signals based on the established temperature-reaction kinetic relationship and multiple temperature signals. These feedback control signals are used to adjust the heating state of each electric heating element.

[0079] The temperature field simulation module transmits feedback control signals to the feedback control unit, which then controls multiple electric heating elements to adjust their heating states. Adjustment of the heating states may include, but is not limited to, adjusting the power of each electric heating element individually, or stopping one or more electric heating elements from heating.

[0080] Through the collaboration of multiple electric heating elements and temperature control sensors, the preheating of the leaching solution is stabilized at the target temperature.

[0081] Specifically, the preheating time is usually determined based on the preset heating time, generally 1 to 3 hours (not less than 1 hour). The target temperature is 35 to 55℃, and the temperature fluctuation range does not exceed ±2℃.

[0082] By strategically placing electric heating elements and temperature control sensors within the injection well, precise preheating of the leaching solution can be achieved.

[0083] In step S103, oxygen and carbon dioxide are introduced into the leaching solution to form a leaching agent, which is then injected into the ore-bearing aquifer through an injection pipeline for uranium leaching.

[0084] After the leaching solution in the injection well stabilizes at the target temperature, oxygen and carbon dioxide are introduced into the leaching solution to form a leaching agent. The leaching agent is then injected into the underground mineral-bearing aquifer through the injection pipeline to begin uranium leaching.

[0085] In some optional embodiments, step S103, which involves introducing oxygen and carbon dioxide into the leaching solution to form a leaching agent, and injecting the leaching agent into the mineral-bearing aquifer through an injection pipeline for uranium leaching, includes: introducing oxygen into the leaching solution to form a primary leaching agent; injecting the primary leaching agent into the mineral-bearing aquifer through an injection pipeline for uranium leaching; detecting the residual oxygen concentration in the uranium-bearing leaching solution produced from the mineral-bearing aquifer; when the residual oxygen concentration is greater than 5 mg / L, introducing carbon dioxide into the primary leaching agent to adjust the pH value to 6.0–7.5 to form a leaching agent; and injecting the leaching agent into the mineral-bearing aquifer through an injection pipeline to continue the uranium leaching operation.

[0086] Oxygen is introduced into the leaching solution to form a primary leaching agent, and the oxygen concentration in the primary leaching agent ranges from 200 to 400 mg / L.

[0087] The primary leaching agent is injected into the underground mineral-bearing aquifer through injection pipelines to begin uranium leaching. Simultaneously, the residual oxygen concentration in the uranium-bearing leachate produced from the underground mineral-bearing aquifer is monitored in real time using online monitoring equipment (such as a residual oxygen analyzer).

[0088] When the residual oxygen concentration is greater than 5 mg / L, carbon dioxide is continuously introduced to form a leaching agent. The carbon dioxide concentration in the leaching agent ranges from 200 to 600 mg / L, and the pH value of the leaching agent is 6.0 to 7.5. Preferably, the pH value is 6.5 to 7.0, which is in a neutral range. This avoids the rock strata from being too low and causing corrosion, or the uranium from being too high and inhibiting its dissolution.

[0089] The leaching agent is injected into the ore-bearing aquifer through the injection pipeline to continue the uranium leaching operation.

[0090] In step S104, the uranium-containing leachate produced from the mineralized aquifer is transported to an ion exchange device for uranium adsorption treatment to obtain adsorption tail liquid, which is then returned to step S102 as part of the leaching solution.

[0091] The uranium-bearing leachate from the mineral-bearing aquifer is subjected to ion exchange adsorption treatment to obtain adsorption tailings. The adsorption tailings can be returned to step S102 as part of the leaching solution for recycling.

[0092] In some optional embodiments, step S104, which involves transporting the uranium-containing leachate from the mineralized aquifer to an ion exchange device for uranium adsorption treatment to obtain an adsorbed tail liquid, and returning the adsorbed tail liquid as part of the leaching solution to step S102, includes: treating the uranium-containing leachate from the mineralized aquifer with a strongly basic anion exchange resin to obtain the adsorbed tail liquid; returning the adsorbed tail liquid as part of the leaching solution to step S102, wherein the uranium concentration in the adsorbed tail liquid is less than 5 mg / L; the leaching solution also includes: groundwater containing bicarbonate, wherein the bicarbonate concentration is not less than 150 mg / L.

[0093] Uranium-containing leachate from mineralized aquifers is transported to a surface ion exchange facility via a pumping well. Uranium is then adsorbed using a strongly alkaline anion exchange resin to obtain an adsorbed tailings solution with a uranium concentration of less than 5 mg / L.

[0094] The adsorption tail liquid is returned to the injection well and mixed with newly replenished groundwater containing bicarbonate (bicarbonate concentration not less than 150 mg / L) to form a leaching solution. This solution is then heated and used in subsequent leaching processes to achieve the recycling of the adsorption tail liquid.

[0095] In addition, after ion exchange adsorption treatment, a saturated resin is obtained. The saturated resin can then be transferred to the rinsing process.

[0096] The method for improving uranium leaching efficiency through heating proposed in this application can solve the technical problems of slow leaching reaction rate and low uranium concentration in existing central uranium leaching processes. This method significantly increases the uranium leaching reaction rate by raising the reaction temperature of the leaching system, resulting in a uranium concentration increase of over 10%, and significantly improves the oxidative leaching effect of tetravalent uranium in ore. This method effectively shortens the leaching process, and the entire reaction process does not experience blockage of the well site injection fluid, exhibiting both high efficiency and stability. This method is suitable for large-scale neutral leaching uranium mining engineering applications.

[0097] Figure 2 This diagram illustrates the process flow of the method for improving uranium leaching efficiency in in-situ leaching based on heating, as provided in this application. Please refer to... Figure 2 As shown, this process involves nodes such as a heating system, injection well, ore-bearing aquifer, and uranium hydrometallurgical plant. The process includes the following steps:

[0098] Step S201: Calculate the total heating power of a single well based on the thermal conductivity of the rock strata, the heating area, the density of the leaching solution, the target temperature, the initial temperature, and the preset heating time; determine the number of ceramic electric heating elements to be arranged based on the total heating power of the single well and the power of each ceramic electric heating element; according to the number of elements, asymmetrically arrange the ceramic electric heating elements along the well wall of the injection well in the corresponding area of ​​the mineralized aquifer, with 2 to 4 electric heating elements added in the same well section for every 100 meters of depth, starting from the highest depth of the mineralized aquifer; arrange temperature sensors at the highest depth of the mineralized aquifer, the middle depth of the mineralized aquifer, the bottom depth of the mineralized aquifer, and key nodes through which the leaching agent flows, respectively, wherein each temperature sensor is connected to the temperature field simulation module, and the temperature field simulation module is connected to the feedback control module.

[0099] In step S202, multiple ceramic electric heating rods are used to heat the leaching solution in the injection well; the temperature field simulation module receives multiple temperature signals from multiple temperature sensors in real time, calculates feedback control signals based on the multiple temperature signals, and transmits them to the feedback control module; the feedback control module adjusts the heating state of the multiple ceramic electric heating rods according to the feedback control signals, so that the leaching solution in the injection well is preheated to 35-55℃ for 1-3 hours and the temperature fluctuation range does not exceed 2℃.

[0100] Step S203: Oxygen is introduced into the leaching solution to form a primary leaching agent (oxygen concentration of 200–400 mg / L). The primary leaching agent is injected into the ore-bearing aquifer through an injection pipeline for uranium leaching. The residual oxygen concentration in the uranium-bearing leaching solution produced from the ore-bearing aquifer is monitored. When the residual oxygen concentration is greater than 5 mg / L, carbon dioxide is introduced into the primary leaching agent to adjust the pH to 6.5–7.0 to form a leaching agent (carbon dioxide concentration of 200–600 mg / L). The leaching agent is then injected into the ore-bearing aquifer through an injection pipeline to continue the uranium leaching operation.

[0101] Step S204: The uranium-containing leachate from the mineralized aquifer is treated with a strongly alkaline anion exchange resin to obtain an adsorption tailings (the uranium concentration in the adsorption tailings is less than 5 mg / L).

[0102] Step S205: The adsorption tail liquid and the replenished groundwater containing bicarbonate (bicarbonate concentration not less than 150 mg / L) are mixed to form a leaching solution and returned to the injection well.

[0103] Example 1

[0104] The uranium deposit in Inner Mongolia has a predominantly platy ore body with an average thickness of 7.08 m, an average grade of 0.0492%, and an average uranium content of 5.19 kg / m². 2 The average carbonate content is 2.61%, making it suitable for neutral leaching process.

[0105] I. Indoor Validation Test

[0106] Core samples of sandstone uranium ore from the deposit were taken, crushed to natural particle size and mixed evenly, and catalytic experiments were conducted to improve the uranium leaching reaction rate.

[0107] After crushing and mixing, the core sample was divided into three equal parts. Formation water from the ore-bearing aquifer of the deposit was added at a liquid-to-solid ratio of 5:1, and a three-phase reactor was used as the reaction vessel. Three parallel tests were conducted to determine the effect of increasing the reaction temperature on improving the uranium reaction rate.

[0108] Group 1 Experiment: The reactor temperature was set to 30℃. 400 mg / L CO2 was introduced into the reactor, and the reaction was stopped after stirring for 1 hour. Subsequently, 250 mg / L O2 was introduced into the reactor. Liquid samples were taken at 1, 3, 5, and 7 days for uranium analysis. During the process of venting the reactor and taking samples, the steps of introducing 400 mg / L CO2 and 250 mg / L O2 were repeated.

[0109] Group 2 experiment: The reactor temperature was set to 40℃. 400 mg / L CO2 was introduced into the reactor, and the reaction was stopped after stirring for 1 hour. Subsequently, 250 mg / L O2 was introduced into the reactor. Liquid samples were taken at 1, 3, 5, and 7 days to analyze the uranium content. During the process of venting the reactor and taking samples, the steps of introducing 400 mg / L CO2 and 250 mg / L O2 were repeated.

[0110] Group 3 Experiment: The reactor temperature was set to 50℃. 400 mg / L CO2 was introduced into the reactor, and the reaction was stopped after stirring for 1 hour. Subsequently, 250 mg / L O2 was introduced into the reactor. Liquid samples were taken at 1, 3, 5, and 7 days for uranium analysis. During the process of venting the reactor and taking samples, the steps of introducing 400 mg / L CO2 and 250 mg / L O2 were repeated.

[0111] The leaching effect is shown in Table 1 and Figure 3 Table 1 compares the enhanced leaching effects in the indoor tests of Example 1. Figure 2 This is a graph showing the change of uranium concentration over time during the indoor leaching process in Example 1.

[0112] Table 1:

[0113]

[0114] As shown in Table 1, in all three groups of experiments, the uranium concentration in the leachate increased with increasing reaction time. Furthermore, the uranium leaching rate continuously increased with increasing reaction temperature. Simultaneously, according to the definition of reaction rate, the uranium leaching reaction rate can be characterized as: Δv(U)=Δc(U) / Δt, where v represents the reaction rate, c represents the uranium concentration, and t represents time. The slope of the uranium concentration versus time curve can characterize the uranium leaching reaction rate. Figure 3It can be seen that increasing the reaction temperature can effectively increase the uranium leaching reaction rate.

[0115] II. On-site Implementation Verification

[0116] Verification of improved leaching efficiency through downhole heating was conducted at the test site.

[0117] Step (1): Arrange 10 5kW ceramic electric heating rods asymmetrically along the wellbore for each well; set 4 temperature measuring points, located at the top, middle, and bottom of the ore layer and 10m downstream of the injection well. Set the target temperature to 45℃ and the dead zone to ±2℃.

[0118] Step (2): Preheat the leaching solution.

[0119] Step (3): The leaching solution is mixed with oxygen to form a primary leaching agent, which is then injected into the underground mineral-bearing aquifer through an injection pipeline at a flow rate of 1.5 m / s. 3 / h, the oxygen concentration in the leaching agent is 300mg / L; the residual oxygen concentration in the leachate is detected during the leaching process; after 7 days, if the residual oxygen concentration is greater than 5mg / L, 400mg / L carbon dioxide is added to the primary leaching agent to form a new leaching agent with a pH of 6.5.

[0120] Step (4): The obtained leachate is passed through an ion exchange adsorption tower. The treated adsorption tail liquid is heated and purged with 300 mg / L oxygen and 400 mg / L carbon dioxide to prepare a solvent for injection into the injection hole.

[0121] Samples are taken daily from the mining area to analyze uranium concentration. Figure 4 This is a graph showing the change in uranium concentration over time during the leaching process in the field test of Example 1. Figure 4 As shown, on the 30th day of downhole heating operation, the concentration of uranium in the uranium-containing leachate rose to 17.1 mg / L.

[0122] Example 2

[0123] The uranium deposit in Xinjiang has a banded ore body with an average thickness of 8.15 m, an average grade of 0.061%, and an average uranium content of 4.85 kg / m². 2 The average carbonate content is 2.74%, and it is mined using a neutral leaching process. The leaching conditions are: HCO3- in the tailings of the hydrometallurgical adsorption solution from the in-situ uranium mine. - The concentration of uranium in the leaching agent was 2500 mg / L, with a carbon dioxide concentration of 550 mg / L and an oxygen concentration of 400 mg / L. During the leaching process, the uranium concentration decreased from 61.5 mg / L at the initial stage to below 12 mg / L, with a leaching rate of 65.3%. This test site was chosen to verify the improvement of leaching efficiency through downhole heating.

[0124] Step (1): Arrange 10 6kW ceramic electric heating rods in each well, asymmetrically along the wellbore; set 3 temperature measuring points, located at the top, middle and bottom of the ore layer respectively. Set the target temperature to 40℃ and the control dead zone to ±2℃.

[0125] Step (2): Preheat the leaching solution.

[0126] Step (3): The leaching solution is mixed with oxygen and carbon dioxide to form a leaching agent, which is then injected into the underground mineral-bearing aquifer through an injection pipeline at a flow rate of 1.8 m / s. 3 The solvent concentration was 550 mg / L for leaching, 400 mg / L for leaching, and pH 6.5. Since the selected test mining area was an old mining area with a residual oxygen concentration of 20 mg / L, oxygen and carbon dioxide could be simultaneously introduced into the leaching solution to prepare the solvent.

[0127] Step (4): The obtained leachate is passed through an ion exchange adsorption tower. The adsorption tail liquid after treatment is heated and purged with 400 mg / L oxygen and 550 mg / L carbon dioxide to prepare a solvent for injection into the injection hole.

[0128] Samples are taken daily from the mining area to analyze uranium concentration. Figure 5 This is a graph showing the change in uranium concentration over time during the leaching process in the field test of Example 2. Figure 5 As shown, starting from the initial downhole heating point, the concentration of uranium in the uranium-containing leachate increased on the 7th day of downhole heating operation, and on the 22nd day, the concentration of uranium in the uranium-containing leachate increased to 23.14 mg / L.

[0129] The above description is merely a specific embodiment of this application. Under the guidance of the above teachings, those skilled in the art can make other improvements or modifications based on the above embodiments. Those skilled in the art should understand that the above specific description is only to better explain the purpose of this application, and the scope of protection of this application should be determined by the scope of the claims.

[0130] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features but not others included in other embodiments, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the following claims, any of the claimed embodiments can be used in any combination.

Claims

1. A method for improving the efficiency of uranium leaching in in-situ mining based on heating, characterized in that, The method includes: Step (1): Based on the injection well parameters and ore body distribution characteristics, multiple electric heating elements and temperature control sensors are arranged in the injection well; Step (2) involves using multiple electric heating elements and temperature control sensors to preheat the leaching solution injected into the well to the target temperature and maintain it stable. Step (3): Oxygen and carbon dioxide are introduced into the leaching solution to form a leaching agent, and the leaching agent is injected into the mineral-bearing aquifer through the injection pipeline for uranium leaching operation; Step (4) involves transporting the uranium-containing leachate from the mineralized aquifer to an ion exchange device for uranium adsorption treatment to obtain adsorption tail liquid, which is then returned to step (2) as part of the leaching solution.

2. The method for improving the efficiency of in-situ uranium leaching based on heating according to claim 1, characterized in that, Step (1) involves arranging multiple electric heating elements and temperature control sensors within the injection well, based on the injection well parameters and ore body distribution characteristics. The total heating power of a single well is calculated based on the thermal conductivity of the rock strata, the heating area, the density of the leaching solution, the target temperature, the initial temperature, and the preset heating time. The number of electric heating elements and the location of each electric heating element are determined based on the total heating power of a single well, the parameters of the mineral-bearing aquifer, and the power of each electric heating element. Multiple electric heating elements are arranged according to their quantity and location.

3. The method for improving the efficiency of in-situ uranium leaching based on heating according to claim 2, characterized in that, The calculation of the total heating power of a single well based on the thermal conductivity of the rock strata, the heating area, the density of the leaching solution, the target temperature, the initial temperature, and the preset heating time includes: The total heating power of a single well is determined according to the following formula (1): P = k × A × ρ × (T) Set -T init ) / t, formula (1); Where P represents the total heating power of a single well, k represents the thermal conductivity of the rock formation, A represents the heating area, ρ represents the density of the leaching solution, and T represents the total heating power of a single well. set T represents the target temperature. init t represents the initial temperature, and t represents the preset heating time. The determination of the number of electric heating elements and the placement of each electric heating element based on the total heating power of a single well, the parameters of the mineral-bearing aquifer, and the power of each electric heating element includes: The number of elements to be arranged is determined based on the total heating power of a single well and the power of each electric heating element. Depending on the number of elements to be deployed, the electric heating elements are asymmetrically arranged along the well wall of the injection well in the corresponding area of ​​the mineralized aquifer. Starting from the highest depth of the mineralized aquifer, 2 to 4 electric heating elements are added in the same well section for every 100 meters increase in depth.

4. The method for improving the efficiency of in-situ uranium leaching based on heating according to claim 1, characterized in that, The electric heating element is a ceramic electric heating rod.

5. The method for improving the efficiency of in-situ uranium leaching based on heating according to claim 1, characterized in that, Step (1) involves arranging multiple electric heating elements and temperature control sensors within the injection well, based on the injection well parameters and ore body distribution characteristics. Temperature sensors are deployed at the highest depth of the mineral-bearing aquifer, the middle depth of the mineral-bearing aquifer, the bottom depth of the mineral-bearing aquifer, and at key nodes through which the leaching agent flows. Each temperature sensor is connected to a temperature field simulation module, which in turn is connected to a feedback control module.

6. The method for improving the efficiency of in-situ uranium leaching based on heating according to claim 5, characterized in that, Step (2), which utilizes multiple electric heating elements and temperature control sensors to preheat the leaching solution in the injection well to the target temperature and maintain it stably, includes: Multiple electric heating elements are used to heat the leaching solution in the injection well; The temperature field simulation module receives multiple temperature signals from multiple temperature sensors in real time, calculates feedback control signals based on the multiple temperature signals, and transmits them to the feedback control module. The feedback control module adjusts the heating status of multiple electric heating elements according to the feedback control signal, so that the leaching solution in the injection well is preheated to the target temperature and maintained stably.

7. The method for improving the efficiency of in-situ uranium leaching based on heating according to claim 1, characterized in that, The preheating time is 1 to 3 hours, and the target temperature is 35 to 55°C with a temperature fluctuation range not exceeding 2°C.

8. The method for improving the efficiency of in-situ uranium leaching based on heating according to claim 1, characterized in that, Step (3), which involves introducing oxygen and carbon dioxide into the leaching solution to form a leaching agent, and then injecting the leaching agent into the ore-bearing aquifer through an injection pipeline for uranium leaching, includes: Oxygen is introduced into the leaching solution to form a primary leaching agent, which is then injected into the ore-bearing aquifer through an injection pipeline for uranium leaching operations. Detect the residual oxygen concentration in uranium-bearing leachate produced from mineral-bearing aquifers; When the residual oxygen concentration is greater than 5 mg / L, carbon dioxide is introduced into the primary leaching agent to make the pH value 6.0-7.5 to form a leaching agent. The leaching agent is then injected into the ore-bearing aquifer through the injection pipeline to continue the uranium leaching operation.

9. The method for improving the efficiency of in-situ uranium leaching based on heating according to claim 8, characterized in that, The oxygen concentration in the leaching agent is 200–400 mg / L, and the carbon dioxide concentration in the leaching agent is 200–600 mg / L.

10. The method for improving the efficiency of in-situ uranium leaching based on heating according to claim 1, characterized in that, Step (4) involves transporting the uranium-bearing leachate from the mineralized aquifer to an ion exchange device for uranium adsorption treatment to obtain adsorption tailings. The adsorption tailings are then returned to step (2) as part of the leaching solution. This includes: The uranium-containing leachate from the mineral-bearing aquifer is treated with a strongly alkaline anion exchange resin to obtain the adsorption tailings. The adsorption tail liquid is returned to step (2) as part of the leaching solution, wherein the uranium concentration in the adsorption tail liquid is less than 5 mg / L; The leaching solution also includes: groundwater containing bicarbonate, wherein the concentration of bicarbonate is not less than 150 mg / L.

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