Sandstone uranium ore gas-liquid alternative leaching method

Abstract

The application provides a sandstone uranium mine gas-liquid alternating leaching method, which comprises the following steps: S1, injecting a leaching agent into a core column filled with a naturally broken sample until the leaching agent fills the core column; S2, injecting oxygen into the core column, raising the pressure in the core column to a first target pressure P1 and maintaining the pressure until a first target time, so that the sample reacts under the action of the leaching agent containing dissolved oxygen to form a reaction solution; S3, transferring the reaction solution in the core column to the intermediate container; the application has the beneficial effect that the sample in the core column is subjected to gas-liquid alternating leaching, the oxygen in the leaching liquid reacts with the sample to alternately change into an oxygen-rich gaseous state, so that the mineral is in a wetted state, the surface liquid film layer is thinned, the diffusion of oxygen at the gas-liquid interface is facilitated, the oxidation rate is accelerated, when the liquid film surface and the ion concentration difference in the leaching agent are converted into an oxygen-rich liquid state again, the hydrodynamic dispersion process is accelerated, and thus the leaching rate is improved.

Description

Technical Field

[0001] This application belongs to the field of uranium hydrometallurgical technology, specifically relating to a method for alternating gas-liquid leaching of sandstone uranium ore. Background Technology

[0002] The existing neutral leaching process uses oxygen as an oxidant. The oxygen is dissolved in a leaching agent containing bicarbonate, which then reacts with the ore in a water-rock reaction. This oxidizes U(Ⅳ) in the ore to U(Ⅵ), which then complexes with bicarbonate to form soluble uranyl carbonate, ultimately achieving uranium extraction. In this process, the mineral is continuously immersed in an oxygen-rich solution, resulting in a relatively stable reaction.

[0003] However, leaching kinetics studies show that the leaching rate of existing neutral leaching processes is mainly controlled by the diffusion process, which specifically includes two key stages: internal diffusion and external diffusion. Internal diffusion corresponds to the solid-liquid reaction between the mineral and the leaching agent, while external diffusion is the process by which uranium elements complex to form uranyl ions after the solid mineral is dissolved. These two steps together constitute the rate-limiting stage of uranyl ion leaching. Under the reaction conditions of existing processes, the mineral dissolution rate and the ion complexation rate remain in a stable equilibrium for a long time, making it difficult to further increase the leaching rate and restricting the efficiency of sandstone uranium mining. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0005] To address the aforementioned problems, this application provides a method for alternating gas-liquid leaching of sandstone uranium ore, comprising the following steps:

[0006] S1. Inject leaching agent into the core column containing the naturally broken sample until the core column is filled with leaching agent.

[0007] S2. Inject oxygen into the core column to raise the pressure inside the core column to the first target pressure P1 and maintain this pressure for the first target time, so that the sample reacts under the action of the dissolved oxygen leaching agent to form a reaction solution.

[0008] S3. Transfer the reaction solution in the core column to the intermediate container. During this process, the core column is filled with oxygen and maintained at the first target pressure P1 for the second target time, so that the sample can react in the wetted state.

[0009] S4. The reaction solution in the intermediate container is returned to the core column, oxygen is injected again, and the pressure is maintained at the first target pressure P1 for the third target time.

[0010] S5. Steps 2-4 are repeated to achieve cyclic leaching of the sample in the core column to obtain the target leaching solution. The target leaching solution is sampled and tested at different set times to detect the concentration and dissolved oxygen concentration of the target leaching solution at different set times.

[0011] Optionally, a leaching agent is injected into a core column containing naturally broken samples until the core column is completely filled with the leaching agent, including:

[0012] A liquid inlet pipe and a configuration slot are provided on the top of the core column. A first air inlet pipe and a second air inlet pipe are provided on the core column. The first air inlet pipe is connected to the liquid inlet pipe. A first pressure gauge is provided on the top of the core column. A first control valve, a second control valve, and a third control valve are respectively installed on the liquid inlet pipe, the first air inlet pipe, and the second air inlet pipe. A first detection pipe and a connecting pipe are provided on the bottom of the core column. The connecting pipe is located between the core column and the intermediate container. A fourth control valve and a fifth control valve are respectively installed on the first detection pipe and the connecting pipe.

[0013] With the first control valve, second control valve, third control valve, fourth control valve, and fifth control valve closed, the naturally broken sample is placed into the core column, the leachate is prepared and placed in the preparation tank, the first control valve and fourth control valve are opened, and the leachate enters the core column through the first inlet pipe until the leachate flows out of the first detection pipe, at which point the fourth control valve is closed.

[0014] Optionally, oxygen is injected into the core column to raise the pressure inside the core column to a first target pressure P1 and maintain this pressure for a first target time, allowing the sample to react under the action of a dissolved oxygen leaching agent to form a reaction solution, including:

[0015] The first control valve is closed, and the second control valve is opened. The oxygen enters the core column through the first air inlet pipe. When the first pressure gauge reaches the first target pressure P1, the pressure is stopped. The second control valve is then closed. The core column maintains the first target pressure P1 for the first target time, allowing the sample to react under the action of the dissolved oxygen leaching agent to form a reaction solution.

[0016] Optionally, the reaction solution within the core column is transferred to the intermediate container, during which the core column is filled with oxygen and maintained at a first target pressure P1 for a second target time, so that the sample reacts in a wetted state, including:

[0017] The intermediate container includes a container body and a piston disposed inside the container body. A third air inlet pipe, a fourth air inlet pipe and a second pressure gauge are disposed on the top of the container body. The fourth air inlet pipe is connected to the third air inlet pipe. A second detection pipe is disposed at the bottom of the container body. A sixth control valve, a seventh control valve and an eighth control valve are respectively disposed on the third air inlet pipe, the fourth air inlet pipe and the second detection pipe.

[0018] While maintaining the first target pressure P1 within the core column, the sixth control valve is opened, and nitrogen gas enters the intermediate container through the third inlet pipe, maintaining the pressure within the intermediate container at the second target pressure P2. During this process, the pressure within the core column remains at the first target pressure P1, where the first target pressure P1 > the second target pressure P2 ≥ the first target pressure P1 - 0.02 MPa. Then, the fifth control valve is opened, and the reaction solution within the core column enters the intermediate container through the connecting pipe.

[0019] After the reaction solution enters the intermediate container, the fifth control valve on the connecting pipe is closed. At this time, the core column is filled with oxygen, and the pressure in the core column is maintained at the first target pressure P1 for the second target time, so that the sample can react in the wetted state.

[0020] Optionally, the reaction solution in the intermediate container is refluxed back to the core column, oxygen is reinjected, and the pressure is maintained at a first target pressure P1 for a third target time, including:

[0021] Close the second control valve and open the third control valve to depressurize the core column through the second air inlet pipe until the pressure reaches the fourth target pressure P3. At this point, the second target pressure P2 > the third target pressure P3 ≥ the second target pressure P2 - 0.02 MPa. Open the fifth control valve. Since the second target pressure P2 is greater than the third target pressure P3, it will drive the piston to move downward in the container body, and return the reaction solution in the container body to the core column through the connecting pipe.

[0022] After the reaction solution enters the core column, the fifth control valve and the third control valve are closed, the second control valve is opened, and oxygen is supplied into the core column through the first air inlet pipe to pressurize the core column, so that the core column maintains the first target pressure P1 and maintains it for the third target time.

[0023] Optionally, steps 2-4 are repeated to achieve cyclic leaching of the sample within the core column, obtaining the target leaching solution. Samples of the target leaching solution are taken and tested at different set times to determine the concentration and dissolved oxygen concentration of the target leaching solution at each set time.

[0024] Steps 2-4 are repeated continuously to achieve cyclic leaching of the sample in the core column. The target leaching solution is sampled through the first and second detection tubes at different set times. The sampled target leaching solution is then tested to detect the concentration of the target leaching solution and the dissolved oxygen concentration.

[0025] Optionally, a filter layer is provided inside the core column and above and below the sample.

[0026] Optionally, the first target pressure P1 is between 1 and 2 MPa.

[0027] Optionally, a pump body is provided on the inlet pipe.

[0028] Optionally, the first target time, the second target time, the third target time, and the fourth target time are all 24 hours.

[0029] Beneficial effects

[0030] The sandstone uranium ore gas-liquid alternating leaching method provided in the embodiments of the present invention enables the sample in the core column to be leached in gas and liquid alternately. The oxygen in the leaching solution reacts with the sample to undergo oxidation, alternatingly changing to an oxygen-rich state. This makes the liquid film layer on the surface of the mineral thinner in the wetted state, which facilitates the diffusion of oxygen at the gas-liquid interface and accelerates the oxidation rate. When it is converted back to an oxygen-rich liquid state, the ion concentration difference between the liquid film surface and the leaching agent accelerates the hydrodynamic dispersion process, thereby improving the leaching rate. Attached Figure Description

[0031] Figure 1 This is a flowchart of a gas-liquid alternating leaching method for sandstone uranium ore according to the present invention;

[0032] Figure 2 This is a structural diagram of a gas-liquid alternating leaching method for sandstone uranium ore according to the present invention.

[0033] The reference numerals in the attached figures are as follows:

[0034] 1. Sample; 2. Core column; 3. Intermediate container; 4. Liquid inlet pipe; 5. Preparation tank; 6. First air inlet pipe; 7. Second air inlet pipe; 8. First pressure gauge; 9. First control valve; 10. Second control valve; 11. Third control valve; 12. First detection tube; 13. Connecting pipe; 14. Fourth control valve; 15. Fifth control valve; 16. Container body; 17. Piston; 18. Third air inlet pipe; 19. Fourth air inlet pipe; 20. Second pressure gauge; 21. Second detection tube; 22. Sixth control valve; 23. Seventh control valve; 24. Eighth control valve. Detailed Implementation

[0035] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention 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, they should not be construed as limiting the present invention.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0037] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0038] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0039] See also Figure 1-2 As shown, an embodiment of this application provides a method for alternating gas-liquid leaching of sandstone uranium ore, comprising the following steps:

[0040] S1. Inject leaching agent into the core column 2 containing the naturally broken sample 1 until the core column 2 is filled with leaching agent.

[0041] Specifically, the leaching agent is By completely filling the core column 2 with leaching agent, the leaching agent can fully contact all particles of sample 1, not only covering the outer surface of sample 1, but also penetrating into the pores and fissures of sample 1. This avoids insufficient reaction due to local lack of leaching agent, thereby ensuring that uranium minerals can be efficiently converted into soluble uranyl carbonate complexes. At the same time, after the core column 2 is filled with leaching agent, residual air in the core column 2 can be discharged, preventing air from interfering with the oxygen dissolution efficiency in the subsequent oxygen injection stage.

[0042] S2. Inject oxygen into the core column 2 to raise the pressure inside the core column 2 to the first target pressure P1 and maintain the pressure for the first target time, so that the sample 1 reacts under the action of the dissolved oxygen leaching agent to form a reaction solution.

[0043] Specifically, after filling core column 2 with leaching agent, oxygen was injected and the pressure and time were controlled. The pressurized environment significantly increased the solubility of oxygen in the leaching agent, providing sufficient oxidizing activity. Maintaining the pressure for the first target time ensured the oxidation reaction proceeded fully, allowing the water-insoluble U(Ⅳ) in sample 1 to be completely oxidized to the readily soluble U(Ⅵ). The oxidized U(Ⅵ) could then react with the pre-set leaching agent... Rapid complexation forms a stable and water-soluble uranyl carbonate complex, ultimately resulting in a reaction solution that can be subsequently separated and extracted.

[0044] S3. The reaction solution in the core column 2 is transferred to the intermediate container 3. During this process, the core column 2 is filled with oxygen and maintained at the first target pressure P1 for the second target time, so that the sample 1 can react in the wetted state.

[0045] Specifically, after completing the oxygen-enriched liquid leaching, by transferring the reaction solution and simultaneously maintaining the oxygen-enriched high-pressure environment inside the core column 2, the leaching process can be transformed from a solid-liquid reaction mode to a gas-liquid-solid three-phase reaction mode. After the reaction solution is transferred, the sample 1 is still in a wetted state, with a thin liquid film remaining on its surface. Under the pressure of P1, the oxygen filled inside the core column 2 can quickly pass through the thin liquid film and come into contact with the sample 1, significantly reducing the mass transfer resistance of oxygen diffusion and enhancing the oxidation reaction of deep uranium minerals. At the same time, maintaining the second target time can ensure that the three-phase reaction proceeds fully, continuously converting the incompletely oxidized U(Ⅳ) in the sample 1 into U(Ⅵ), thereby improving the overall leaching efficiency.

[0046] S4. The reaction solution in the intermediate container 3 is returned to the core column 2, oxygen is injected again, and the pressure is maintained at the first target pressure P1 for the third target time.

[0047] Specifically, by refluxing the reaction solution into core column 2, the refluxing reaction solution already contains a certain concentration of uranyl carbonate, which, together with the newly generated U(VI) on the surface and in the pores of sample 1, promotes the rapid detachment of uranyl ions from the mineral surface into the solution. Re-injecting oxygen and maintaining the first target pressure P1 can replenish the dissolved oxygen consumed in the previous reaction, providing sufficient oxidant for the incompletely oxidized U(Ⅳ). The continuous pressure maintenance for the third target time can ensure that the reaction proceeds fully, further improving the uranium leaching rate, while realizing the efficient recycling of the leaching agent and avoiding resource waste.

[0048] S5. Steps 2-4 are repeated to achieve cyclic leaching of sample 1 in the core column 2 to obtain the target leaching solution. The target leaching solution is sampled and tested at different set times to detect the concentration and dissolved oxygen concentration of the target leaching solution at different set times.

[0049] Specifically, by repeating steps 2-4, leaching can be continuously enhanced. Each cycle allows the uranium minerals in sample 1 that have not been leached to continue to participate in the reaction, gradually increasing the uranium concentration in the target leaching solution and ultimately achieving a high leaching rate. Meanwhile, timed sampling and detection provide data support for the leaching rate during the cycle.

[0050] In some feasible embodiments, a leaching agent is injected into a core column 2 containing a naturally broken sample 1 until the core column 2 is completely filled with the leaching agent, including:

[0051] A liquid inlet pipe 4 and a configuration slot 5 are provided on the top of the core column 2. A first air inlet pipe 6 and a second air inlet pipe 7 are provided on the core column 2. The first air inlet pipe 6 is connected to the liquid inlet pipe 4. A first pressure gauge 8 is provided on the top of the core column 2. A first control valve 9, a second control valve 10, and a third control valve 11 are respectively installed on the liquid inlet pipe 4, the first air inlet pipe 6, and the second air inlet pipe 7. A first detection pipe 12 and a connecting pipe 13 are provided on the bottom of the core column 2. The connecting pipe 13 is located between the core column 2 and the intermediate container 3. A fourth control valve 14 and a fifth control valve 15 are respectively installed on the first detection pipe 12 and the connecting pipe 13.

[0052] With the first control valve 9, the second control valve 10, the third control valve 11, the fourth control valve 14, and the fifth control valve 15 closed, the naturally broken sample 1 is placed into the core column 2, the leachate is prepared and placed in the preparation tank 5, the first control valve 9 and the fourth control valve 14 are opened, and the leachate enters the core column 2 through the first inlet pipe 4 until the leachate flows out of the first detection pipe 12, at which point the fourth control valve 14 is closed.

[0053] In this technical solution, a pre-prepared concentration of 1 g / L is used. The leaching agent is placed in the preparation tank 5, ensuring that the volume of the leaching agent and the internal space of the intermediate container 3 are both larger than the internal space of the core column 2. This allows the leaching agent to fill the internal space of the core column 2, and the internal space of the intermediate container 3 can store the transfer of the reaction solution inside the core column 2. After loading the naturally broken sample 1 into the core column 2, all first control valves 9, second control valve 10, third control valve 11, fourth control valve 14, and fifth control valve 15 are closed before operation. The prepared leaching agent is placed in the preparation tank 5, and the first control valve 9 and the fourth control valve 14 are opened. The leaching agent gradually permeates along the gaps, pores, and cracks between the particles of sample 1. When leaching liquid continuously flows out of the first detection tube 12, it indicates that the leaching agent has completely filled all the spaces inside the core column 2. At this time, the fourth control valve 14 is closed to ensure all-round contact between the leaching agent and the uranium mineral.

[0054] Understandably, naturally broken sample 1 can simulate the particle accumulation state of actual strata, thus improving the authenticity and reliability of the test results.

[0055] Understandably, the first detection tube 12 has a criterion for judging the outflow of leachate. If the outflow is continuous without bubbles, it indicates that the air inside the column has been completely purged, ensuring sufficient contact between the leachate and the sample 1.

[0056] Understandably, the first pressure gauge 8 is used to monitor the pressure inside the core column 2.

[0057] In some feasible embodiments, oxygen is injected into the core column 2 to raise the pressure inside the core column 2 to a first target pressure P1 and maintain this pressure for a first target time, so that the sample 1 reacts under the action of a dissolved oxygen leaching agent to form a reaction solution, including:

[0058] The first control valve 9 is closed, and the second control valve 10 is opened. The oxygen enters the core column 2 through the first air inlet pipe 6. When the first pressure gauge 8 reaches the first target pressure P1, the pressure is stopped. The second control valve 10 is closed, and the core column 2 maintains the first target pressure P1 for the first target time, so that the sample 1 reacts under the action of the dissolved oxygen leaching agent to form a reaction solution.

[0059] In this technical solution, after the core column 2 is filled with leaching agent, closing the first control valve 9 isolates the leaching agent supply channel. Opening the second control valve 10 allows oxygen to be directionally injected into the core column 2 via the first air inlet pipe 6. This high-pressure environment significantly increases the solubility of oxygen in the leaching agent, providing sufficient oxidant for the oxidation of U(Ⅳ). When the first pressure gauge 8 displays the first target pressure P1, closing the second control valve 10 and maintaining this pressure until the first target time ensures the oxidation reaction proceeds fully, completely converting the insoluble U(Ⅳ) in sample 1 into the readily soluble U(Ⅵ), and reacting with the leaching agent... Rapid complexation forms a stable uranyl carbonate complex, ultimately generating a reaction solution that can be subsequently separated and extracted, thus improving leaching efficiency.

[0060] Understandably, the first target time is 24 hours.

[0061] In some feasible embodiments, the reaction solution within the core column 2 is transferred to the intermediate container 3, during which the core column 2 is filled with oxygen and maintained at a first target pressure P1 for a second target time, so that the sample 1 reacts in a wetted state, including:

[0062] The intermediate container 3 includes a container body 16 and a piston 17 disposed within the container body 16. A third air inlet pipe 18, a fourth air inlet pipe 19, and a second pressure gauge 20 are disposed on the top of the container body 16. The fourth air inlet pipe 19 is connected to the third air inlet pipe 18. A second detection pipe 21 is disposed at the bottom of the container body 16. A sixth control valve 22, a seventh control valve 23, and an eighth control valve 24 are respectively disposed on the third air inlet pipe 18, the fourth air inlet pipe 19, and the second detection pipe 21.

[0063] While maintaining the first target pressure P1 within the core column 2, the sixth control valve 22 is opened, and nitrogen gas enters the intermediate container 3 through the third inlet pipe 18, maintaining the pressure within the intermediate container 3 at the second target pressure P2. During this process, the pressure within the core column 2 remains at the first target pressure P1, where the first target pressure P1 > the second target pressure P2 ≥ the first target pressure P1 - 0.02 MPa. Then, the fifth control valve 15 is opened, and the reaction solution within the core column 2 enters the intermediate container 3 through the connecting pipe 13.

[0064] After the reaction solution enters the intermediate container 3, the fifth control valve 15 on the connecting pipe 13 is closed. At this time, the core column 2 is filled with oxygen, and the pressure in the core column 2 is maintained at the first target pressure P1 for the second target time so that the sample 1 can react in the wetted state.

[0065] In this technical solution, under the premise that the core column 2 maintains the first target pressure P1, nitrogen gas is injected through the third air inlet pipe 18 to make the intermediate container 33 reach the second target pressure P2. The first target pressure P1 > the second target pressure P2 ≥ the first target pressure P1 - 0.02 MPa. Because there is a pressure difference between the second target pressure P2 and the first target pressure P1, when the fifth control valve 15 on the connecting pipe 13 is opened, the reaction solution in the core column 2 will enter the intermediate container 3 through the connecting pipe 13. The second target pressure P2 ≥ the first target pressure P1 - 0.02 MPa ensures that the pressure difference between the core column 2 and the intermediate container 3 is maintained. A small pressure difference is generated, which avoids the erosion of sample 1 particles or pore collapse caused by a high pressure difference, and also pushes the reaction solution to flow smoothly into the intermediate container 33 along the connecting pipe 13. The piston 17 moves synchronously with the solution injection, which can adaptively adjust the volume and pressure in the container body 16 to ensure that the pressure in the core column 2 remains stable during the transfer process, and avoids oxygen leakage or air mixing. After the reaction solution is transferred, the fifth control valve 15 is closed, and the core column 22 is completely filled with oxygen. Sample 1 maintains the first target pressure P1 in the immersion state until the second target time, so that sample 1 can carry out a gas-liquid-solid three-phase reaction and continuously oxidize the unreacted U(Ⅳ).

[0066] Understandably, the second target time is 24 hours.

[0067] Understandably, the second pressure gauge 20 is used to monitor the pressure inside the intermediate container 3.

[0068] It is understandable that by setting a piston 17 in the intermediate container 3, when the reaction solution is injected, the piston 17 moves upward to counteract the pressure impact caused by the volume of the solution, so that P2 is always stable within the set range; the fourth air inlet pipe 19 and the third air inlet pipe 18 are connected to the intermediate container 3, which can quickly replenish the gas when the nitrogen injection is insufficient, or adjust the pressure through the pressure relief branch when the pressure is too high. With the real-time monitoring of the second pressure gauge 20, the control of P2 can be achieved.

[0069] It is understandable that after the reaction solution is discharged into the intermediate container 3, the thin liquid film remaining on the surface of sample 1 provides a liquid medium for the oxidation reaction of oxygen and U(Ⅳ). High-pressure oxygen can quickly penetrate through the thin liquid film to the depth of the pores of sample 1 and fully contact the unoxidized uranium minerals. The reaction rate can be effectively improved compared with a single liquid reaction. The setting of the second target time can ensure that the thin liquid film exists stably and the oxidation reaction reaches equilibrium, avoiding incomplete oxidation due to too short a time.

[0070] In some feasible embodiments, the reaction solution in the intermediate container 3 is refluxed back to the core column 2, oxygen is reinjected, and the pressure is maintained at a first target pressure P1 for a third target time, including:

[0071] Close the second control valve 10 and open the third control valve 11. Depressurize the core column 2 through the second air inlet pipe 7 until the pressure reaches the fourth target pressure P3. At this time, the second target pressure P2 > the third target pressure P3 ≥ the second target pressure P2 - 0.02 MPa. Open the fifth control valve 15. Since the second target pressure P2 is greater than the third target pressure P3, the piston 17 will move downward in the container body 16, and the reaction solution in the container body 16 will flow back to the core column 2 through the connecting pipe 13.

[0072] After the reaction solution enters the core column 2, the fifth control valve 15 and the third control valve 11 are closed, the second control valve 10 is opened, and oxygen is supplied into the core column 2 through the first air inlet pipe 6 to pressurize the core column 2, so that the core column 2 maintains the first target pressure P1 and maintains it for the third target time.

[0073] In this technical solution, the second control valve 10 is first closed, and the third control valve 11 is opened to depressurize the core column 2 to the third target pressure P3 through the second air inlet pipe 7. At this time, the second target pressure P2 > the third target pressure P3 ≥ the second target pressure P2 - 0.02 MPa. A pressure difference is generated between the second target pressure P2 and the third target pressure P3, which drives the piston 17 to move downward, so that the reaction solution rich in uranyl carbonate complex can be smoothly refluxed into the core column 2 to avoid solution residue. After the reflux is completed, the fifth control valve 15 and the third control valve 11 are closed, and the second control valve 10 is reopened to inject oxygen through the first air inlet pipe 6, pressurizing the core column 2 to the first target pressure P1 and maintaining it for the third target time, so that the reflux solution and high-pressure oxygen can be re-integrated, which can not only achieve the supplementary complexation of uncomplexed U(VI) but also oxidize the newly exposed U(Ⅳ), greatly improving the overall leaching efficiency.

[0074] Understandably, the small pressure difference between the second target pressure P2 and the third target pressure P3 can provide sufficient driving force to make the piston 17 move down at a constant speed to push the reaction solution, while avoiding solution turbulence caused by the high pressure difference. The smooth backflow can prevent the residual oxidation products in the pores from being washed away.

[0075] It is understandable that when the reaction solution is refluxed, the uranyl carbonate complex it carries can quickly combine with the newly generated U(VI) on the surface of sample 1, thereby improving the complexation efficiency. The subsequent high-pressure reoxygenation process can, on the one hand, replenish the oxygen consumed in the three-phase reaction and maintain a sufficient dissolved oxygen concentration in the leaching agent, and on the other hand, the high-pressure environment can accelerate the diffusion of oxygen into the depth of the pores of sample 1, so as to fully react with the unoxidized U(Ⅳ) and increase the leaching amount.

[0076] Understandably, the third target timeframe is 24 hours.

[0077] In some feasible embodiments, steps 2-4 are repeated to achieve cyclic leaching of sample 1 within the core column 2, obtaining the target leaching solution. Samples of the target leaching solution are taken and tested at different set times to detect the concentration and dissolved oxygen concentration of the target leaching solution at each set time.

[0078] Steps 2-4 are repeated continuously to achieve cyclic leaching of sample 1 in the core column 2. The target leaching solution is sampled through the first detection tube 12 and the second detection tube 21 at different set times. The sampled target leaching solution is then tested to detect the concentration of the target leaching solution and the dissolved oxygen concentration.

[0079] In this technical solution, the repetitive cycle of steps 2-4 involves high-pressure oxygen continuously oxidizing U(Ⅳ) in sample 11 during each cycle. The directional transfer and reflux process of the reaction solution continuously enriches the generated uranyl carbonate complex. At the same time, fresh oxygen is continuously replenished to the reaction system, gradually increasing the uranium concentration of the target leaching solution. Based on this, samples can be obtained from the core column 2 and the intermediate container 3 by taking samples at different set times through the first detection tube 12 and the second detection tube 21, respectively, to detect the dual indicators of target leaching solution concentration and dissolved oxygen concentration.

[0080] Understandably, steps 2-4 are repeated, and each cycle will update the reaction interface on the surface of sample 1. Oxygen and leaching agent can continuously penetrate into the depths of unreacted pores. The increase in the number of cycles can significantly improve the comprehensiveness of leaching, so that the uranium leaching rate increases stepwise with the number of cycles until dynamic equilibrium is reached.

[0081] It is understandable that the sampling from the first detection tube 12 can directly reflect the concentration of the reaction solution inside the core column 2; the sampling from the second detection tube 21 can reflect the dissolved oxygen concentration of the reaction solution in the intermediate container 3.

[0082] In some feasible embodiments, a filter layer is provided inside the core column 2 and above and below the sample 1.

[0083] In this technical solution, by setting filter layers on the upper and lower sides of sample 1 inside the core column 2, the blockage of the pipeline caused by fine particles generated by sample 1 can be reduced, thereby improving the stability of the leaching process of sample 1.

[0084] Understandably, the filter layer is made of sponge.

[0085] In some feasible embodiments, the first target pressure P1 is 1~2 MPa.

[0086] In this technical solution, the first target pressure P1 is set at 1~2 MPa to improve the solubility of oxygen in the liquid.

[0087] In some feasible embodiments, a pump body is provided on the inlet pipe 4.

[0088] In this technical solution, a pump body is installed on the inlet pipe 4 to provide power to feed the leachate in the configuration tank 5 into the core column 2, so that the leachate fills the core column 2.

[0089] In some feasible embodiments, the first target time, the second target time, and the third target time are all 24 hours.

[0090] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A method for alternating gas-liquid leaching of sandstone uranium ore, characterized in that, Includes the following steps: S1. Inject leaching agent into the core column (2) filled with naturally broken sample (1) until the core column (2) is filled with leaching agent; S2. Inject oxygen into the core column (2) to raise the pressure inside the core column (2) to the first target pressure P1 and maintain the pressure for the first target time, so that the sample (1) reacts under the action of dissolved oxygen leaching agent to form a reaction solution; S3. The reaction solution in the core column (2) is transferred to the intermediate container (3). During this process, the core column (2) is filled with oxygen and the first target pressure P1 is maintained for the second target time so that the sample (1) can react in the wetted state. S4. The reaction solution in the intermediate container (3) is returned to the core column (2), the oxygen is injected again, and the pressure is maintained at the first target pressure P1 for the third target time. S5. Steps 2-4 are repeated to achieve cyclic leaching of the sample (1) in the core column (2) to obtain the target leaching solution. The target leaching solution is sampled and tested at different set times to detect the concentration and dissolved oxygen concentration of the target leaching solution at different set times.

2. The method for alternating gas-liquid leaching of sandstone uranium ore according to claim 1, characterized in that, Leaching agent is injected into a core column (2) containing a naturally broken sample (1) until the core column (2) is completely filled with leaching agent, including: A liquid inlet pipe (4) and a configuration slot (5) are provided on the top of the core column (2). A first air inlet pipe (6) and a second air inlet pipe (7) are provided on the core column (2). The first air inlet pipe (6) is connected to the liquid inlet pipe (4). A first pressure gauge (8) is provided on the top of the core column (2). A first control valve (9), a second control valve (10), and a third control valve (11) are respectively installed on the liquid inlet pipe (4), the first air inlet pipe (6), and the second air inlet pipe (7). A first detection pipe (12) and a connecting pipe (13) are provided on the bottom of the core column (2). The connecting pipe (13) is located between the core column (2) and the intermediate container (3). A fourth control valve (14) and a fifth control valve (15) are respectively installed on the first detection pipe (12) and the connecting pipe (13). With the first control valve (9), the second control valve (10), the third control valve (11), the fourth control valve (14), and the fifth control valve (15) closed, the naturally broken sample (1) is placed into the core column (2), the leachate is prepared and placed in the preparation tank (5), the first control valve (9) and the fourth control valve (14) are opened, and the leachate enters the core column (2) through the liquid inlet pipe (4) until the leachate flows out of the first detection pipe (12), at which point the fourth control valve (14) is closed.

3. The method for alternating gas-liquid leaching of sandstone uranium ore according to claim 2, characterized in that, Oxygen is injected into the core column (2) to raise the pressure inside the core column (2) to a first target pressure P1 and maintain this pressure for a first target time, so that the sample (1) reacts under the action of the dissolved oxygen leaching agent to form a reaction solution, including: The first control valve (9) is closed, and the second control valve (10) is opened. The oxygen enters the core column (2) through the first air inlet pipe (6). When the first pressure gauge (8) reaches the first target pressure P1, the pressure stops. The second control valve (10) is closed. The core column (2) maintains the first target pressure P1 for the first target time, so that the sample (1) reacts under the action of the dissolved oxygen leaching agent to form a reaction solution.

4. The method for alternating gas-liquid leaching of sandstone uranium ore according to claim 3, characterized in that, The reaction solution in the core column (2) is transferred to the intermediate container (3). During this process, the core column (2) is filled with oxygen and maintained at a first target pressure P1 for a second target time, so that the sample (1) can react in a wetted state, including: The intermediate container (3) includes a container body (16) and a piston (17) disposed inside the container body (16). A third air inlet pipe (18), a fourth air inlet pipe (19) and a second pressure gauge (20) are disposed on the top of the container body (16). The fourth air inlet pipe (19) is connected to the third air inlet pipe (18). A second detection pipe (21) is disposed at the bottom of the container body (16). A sixth control valve (22), a seventh control valve (23) and an eighth control valve (24) are respectively disposed on the third air inlet pipe (18), the fourth air inlet pipe (19) and the second detection pipe (21). While maintaining the first target pressure P1 in the core column (2), the sixth control valve (22) is opened, and nitrogen gas enters the intermediate container (3) through the third air inlet pipe (18), so that the pressure in the intermediate container (3) is maintained at the second target pressure P2. During this process, the pressure in the core column (2) is maintained at the first target pressure P1. The first target pressure P1 > the second target pressure P2 ≥ the first target pressure P1 - 0.02 MPa. The fifth control valve (15) is opened, and the reaction solution in the core column (2) enters the intermediate container (3) through the connecting pipe (13). After the reaction solution enters the intermediate container (3), the fifth control valve (15) on the connecting pipe (13) is closed. At this time, the core column (2) is filled with oxygen, and the pressure in the core column (2) is maintained at the first target pressure P1 for the second target time so that the sample (1) can react in the wetted state.

5. The method for alternating gas-liquid leaching of sandstone uranium ore according to claim 4, characterized in that, The reaction solution in the intermediate container (3) is refluxed back to the core column (2), oxygen is injected again, and the pressure is maintained at the first target pressure P1 for a third target time, including: Close the second control valve (10), open the third control valve (11), and depressurize the core column (2) through the second air inlet pipe (7) until the pressure reaches the third target pressure P3. At this time, the second target pressure P2 > the third target pressure P3 ≥ the second target pressure P2 - 0.02 MPa. Open the fifth control valve (15). Since the second target pressure P2 is greater than the third target pressure P3, the piston (17) will move downward in the container body (16) and return the reaction solution in the container body (16) to the core column (2) through the connecting pipe (13). After the reaction solution enters the core column (2), the fifth control valve (15) and the third control valve (11) are closed, the second control valve (10) is opened, and oxygen is supplied into the core column (2) through the first air inlet pipe (6) to pressurize the core column (2) so that the core column (2) maintains the first target pressure P1 and maintains the third target time.

6. The method for alternating gas-liquid leaching of sandstone uranium ore according to claim 1, characterized in that, Steps 2-4 are repeated to achieve cyclic leaching of the sample (1) inside the core column (2) to obtain the target leaching solution. The target leaching solution is sampled and tested at different set times to detect the concentration and dissolved oxygen concentration of the target leaching solution at different set times: Steps 2-4 are repeated continuously to achieve cyclic leaching of the sample (1) in the core column (2). The target leaching solution is sampled through the first detection tube (12) and the second detection tube (21) at different set times. The sampled target leaching solution is then tested to detect the concentration of the target leaching solution and the dissolved oxygen concentration.

7. The method for alternating gas-liquid leaching of sandstone uranium ore according to claim 1, characterized in that, A filter layer is provided inside the core column (2) and above and below the sample (1).

8. The method for alternating gas-liquid leaching of sandstone uranium ore according to claim 1, characterized in that, The first target pressure P1 is 1~2 MPa.

9. The method for alternating gas-liquid leaching of sandstone uranium ore according to claim 2, characterized in that, A pump body is installed on the inlet pipe (4).

10. The method for alternating gas-liquid leaching of sandstone uranium ore according to claim 1, characterized in that, The first target time, the second target time, and the third target time are all 24 hours.

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