Micro electric field and microorganism synergistic in-situ leaching uranium mining method

Abstract

The invention belongs to the technical field of mining, and provides a micro electric field and microorganism synergistic in-situ leaching uranium mining method. Firstly, an ore-bearing layer is dredged, and conditions are created for contact of an ore leaching agent and an ore body; then, CO2 and O2 are injected into the underground water, subacid pretreatment is carried out under the action of a direct-current electric field, and metal uranium is dissolved; the direct-current electric field enhances ion migration, accelerates oxidation and dissolution of uranium, maintains a weak acid environment and promotes continuous dissolution of uranium. Then, introducing a bacterial solution with a carbonate corrosion function and CO2 into the pretreated ore body; and bacteria in the bacterial liquid can decompose carbonate minerals, insoluble U < 4 + > is oxidized into soluble U < 6 + >, and the U < 6 + > and CO2 form a high-solubility uranyl carbonate complex, so that the uranium concentration and the leaching efficiency are improved, and the leaching time is shortened. The direct-current electric field also can enhance the activity of bacteria in the bacterial liquid, accelerate the corrosion of carbonate and improve the leaching efficiency. According to the method, high-efficiency leaching is realized under the conditions of low acidity and low energy consumption, and the use of chemical reagents and environmental pollution are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mining, in particular to a method for synergistically leaching uranium by micro electric field and microorganism. BACKGROUND

[0002] In-situ leaching uranium mining is a technology that injects leaching agent prepared in a certain proportion through surface drilling to ore-bearing layer to leach uranium in the ore body. The injected leaching agent and oxidizing agent react with uranium minerals in the ore body to form soluble uranium compounds. Then, the leaching solution migrates to the direction of the pumping well in the ore layer through diffusion and convection, and finally the uranium-rich solution is pumped to the surface through the pumping well for further treatment and uranium recovery. Compared with traditional mining methods, in-situ leaching reduces surface damage and waste treatment, and is a more environmentally friendly uranium mining method.

[0003] Among various types of uranium ore, sandstone-type uranium deposits have become the main mining object at present due to relatively low mining cost. The sandstone-type uranium deposits mainly use medium-fine sandstone as the carrier, and the scale and ore body shape are strictly controlled by interlayer oxidation zone, and are usually located around the oxidation-reduction interface in the groundwater runoff, supply and discharge system. However, in recent years, uranium geological exploration and leaching uranium test have revealed that these sandstone-type uranium deposits generally have poor permeability of ore-bearing layer, which brings challenges to mining and leads to low uranium leaching efficiency. SUMMARY

[0004] Therefore, the present application aims to provide an in-situ leaching uranium mining method and system. The method provided by the present application has high uranium leaching efficiency.

[0005] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0006] The present application provides an in-situ leaching uranium mining method, comprising the following steps:

[0007] The groundwater in the ore-bearing layer is pumped through the pumping well, and the pumped groundwater is re-injected into the ore-bearing layer through the liquid injection well, the groundwater is circulated through the liquid passage, and the ore-bearing layer is dredged;

[0008] After dredging, oxygen and carbon dioxide are injected into the groundwater in the ore-bearing layer, and the groundwater is circulated through the liquid passage to realize micro-acid pretreatment; the micro-acid pretreatment is carried out under the condition of applying a direct current electric field;

[0009] After micro-acid pretreatment, carbon dioxide fluid and bacterial solution are injected into the groundwater in the ore-bearing layer, and the groundwater is circulated through the liquid passage to realize uranium leaching; the uranium leaching is carried out under the condition of applying a direct current electric field; the bacterial solution has carbonate dissolution function;

[0010] An adsorption tower is arranged on the liquid passage, and the adsorption tower is used for adsorbing uranium in the leaching solution obtained by uranium leaching.

[0011] Preferably, the time for dredging is 30-40 days.

[0012] Preferably, in the process of the micro-acid pretreatment, the injection pressure of the oxygen is 1-2 MPa, and the injection pressure of the carbon dioxide is 1-3 MPa.

[0013] Preferably, in the process of the micro-acid pretreatment, the intensity of the direct current electric field is 0.1-0.4 V / cm.

[0014] Preferably, in the process of the uranium leaching, the injection pressure of the carbon dioxide is 1-3 MPa, and the injection time is 105-120 min.

[0015] Preferably, the bacteria solution is an ATCC55618 actinobacillus succinogenes solution; the concentration of the bacteria solution is at least 1.0*10 8 ^10 2 ·h).

[0016] Preferably, in the process of the uranium leaching, the intensity of the direct current electric field is 0.1-0.4 V / cm.

[0017] Preferably, when the concentration of the uranium in the leaching solution is reduced to less than 5 mg / L, the process of the uranium leaching is stopped.

[0018] Preferably, the adsorption material in the adsorption tower is an adsorption resin, and the adsorption resin is a D201 strong basic anion exchange resin, the mass exchange capacity of the D201 strong basic anion exchange resin is greater than or equal to 3.7 mmol / g, the volume exchange capacity is greater than or equal to 1.2 mmol / ml, the particle size range is 0.7-1.6 mm, the wet true density is 1.06-1.10 g / mL, the wet apparent density is 0.65-0.73 g / mL, and the sphericity rate is greater than or equal to 90%.

[0019] The application further provides a system for in-situ leaching uranium, which comprises a liquid passage and an electric passage.

[0020] The liquid passage comprises a liquid pumping well arranged in a mineral body, an adsorption tower and a liquid injection well arranged in the mineral body which are sequentially connected; the liquid inlet of the liquid pumping well and the liquid outlet of the liquid injection well are in contact with underground water in an ore-bearing layer; a carbon dioxide inlet is arranged between the liquid outlet of the liquid pumping well and the adsorption tower; an oxygen inlet is arranged between the adsorption tower and the liquid inlet of the liquid injection well; a bacteria solution inlet is arranged between the oxygen inlet and the liquid inlet of the liquid injection well.

[0021] The electric path comprises a positive electrode, a negative electrode and a direct current power supply; the positive electrode and the negative electrode are arranged in the groundwater of the ore-bearing layer, and the positive electrode and the negative electrode are arranged vertically in parallel; the positive electrode is located at the liquid inlet of the liquid pumping well, and the direct current power supply is located on the ground; the negative electrode is located at the liquid outlet of the liquid injection well; the positive electrode, the negative electrode and the direct current power supply are connected through wires.

[0022] The application provides a method for in-situ leaching of uranium.

[0023] Compared with the prior art, the application has the beneficial effects that:

[0024] (1) In the application, the ore-bearing layer is first dredged to provide basic conditions for the contact between the ore leaching agent and the ore body in the ore-bearing layer; then, oxygen (O2) and carbon dioxide (CO2) are injected into the groundwater, and a micro-acid pretreatment is carried out under the condition of applying a direct current electric field, so that the metallic uranium is dissolved from the ore body; the application of the direct current electric field can enhance ion migration, accelerate the oxidation and dissolution process of uranium, and at the same time, optimize the micro-acid environment, maintain the weak acid condition, and promote the continuous dissolution of uranium. Then, the bacteria solution with carbonate dissolution function and carbon dioxide are introduced into the ore body after the micro-acid pretreatment; the bacteria solution with carbonate dissolution function can dissolve the carbonate in the ore body, further dissolve the insoluble U 4+ Oxidation to soluble U 6+ These U 6+ form high-solubility uranyl carbonate complexes with the injected CO2, thereby increasing the concentration of metallic uranium in the leaching solution and the leaching efficiency, and shortening the leaching time, and at the same time, being environmentally friendly. In addition, the application of the electric field can also enhance the metabolic activity of the bacteria solution, accelerate the dissolution of carbonate minerals, further improve the leaching efficiency, and realize high-efficiency leaching under low acidity and low energy consumption, reduce the use of chemical reagents and environmental pollution.

[0025] (2) The micro-acid pretreatment using O2+CO2 in the application is a new type of environmentally friendly leaching method, which has many advantages. The micro-acid pretreatment solvent loss is small, the operation method is simple, and the solvent is easy to recover. In addition, carbon dioxide is non-toxic and very stable in chemical and radiation chemical properties. For low-grade and low-permeability uranium ore bodies in China, carbon dioxide extraction has shown high leaching efficiency.

[0026] (3) In the process of uranium leaching, the leaching solution obtained by uranium leaching can be used as the nutrient substance of the bacteria in the bacteria solution, to promote the growth of the bacteria, and further promote the dissolution effect of the bacteria.

[0027] (4) After the leachate is adsorbed by the adsorption tower, the pH of the adsorption tail liquid is adjusted to a slightly acidic environment (pH 6.0-6.5) and can be used again as a leaching agent, forming a circulation system without the need for additional replenishment. Using bacterial liquid as a solvent can increase the porosity and permeability of the ore body, ultimately increasing the leaching rate of metallic uranium, shortening the leaching time, saving acid consumption, reducing economic costs, and being good for the environment.

[0028] (5) The present invention also increases the activity of bacteria in the bacterial solution by applying a DC electric field, promotes electron transfer during the oxidation process of the ore body, and thus enhances U 4+ The DC electric field enhances the ability to oxidize metals, thereby better coordinating the dissolution efficiency of heavy metals. Under the action of the DC electric field, bacteria in the bacterial solution can directly use the cathode as an electron donor, achieving a higher concentration. This also limits the formation of a passivation layer on the ore surface, increasing the microbial diversity and relative abundance of target microorganisms within the entire community. Furthermore, it increases the contact area between the leaching agent and the ore during subsequent uranium leaching, promoting the continued leaching of uranium and further improving uranium leaching efficiency.

[0029] (6) In the present invention, the bacterial solution can promote the dissolution of ore bodies in the ore-bearing layer, thereby improving the permeability of the ore-bearing layer; at the same time, the bacterial solution can dissolve the insoluble U 4+ Oxidized to soluble U 6+ , these U 6+ It forms a highly soluble uranyl carbonate complex with the injected CO2, thereby increasing the concentration and leaching rate of metallic uranium in the leachate and shortening the leaching time while being environmentally friendly.

[0030] (7) The method of the present invention not only improves the efficiency of uranium mining, but also reduces the impact on the environment, providing a more environmentally friendly and efficient solution for uranium mining.

[0031] Furthermore, an injection pressure of 1 to 3 MPa of carbon dioxide is also relatively easy to obtain, and during use, carbon dioxide can be used as an osmotic pressure generator and can also be recycled. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the in-situ leaching uranium mining system provided by the present invention;

[0033] Figure 1: 1 is the injection well, 2 is the extraction well, 3 is the negative electrode, 4 is the positive electrode, 5 is the DC power supply, 6 is the wire, 7 is the first casing, 8 is the second casing, 9 is the first filter, 10 is the second filter, 11 is the bacterial liquid storage tank, 12 is the submersible pump, 13 is the adsorption tower, 14 is the multimeter, 15 is the air release valve, 16 is the carbon dioxide inlet, 17 is the oxygen inlet, and 18 is the bacterial liquid inlet. DETAILED DESCRIPTION

[0034] The application provides a method for in-situ leaching of uranium, comprising the following steps:

[0035] The underground water in the ore-bearing layer is extracted through the liquid extraction well, and the extracted underground water is re-injected into the ore-bearing layer through the liquid injection well, so that the circulation flow of the underground water is realized through the liquid passage, and the ore-bearing layer is dredged.

[0036] After dredging, oxygen and carbon dioxide are added into the underground water in the ore-bearing layer, and the circulation flow of the underground water is continuously realized through the liquid passage, so that the micro-acid pretreatment is realized; the micro-acid pretreatment is realized under the condition of applying a direct current electric field.

[0037] After the micro-acid pretreatment, carbon dioxide fluid and carbonate leaching bacteria solution are injected into the underground water in the ore-bearing layer, and the circulation flow of the underground water is continuously realized through the liquid passage, so that the uranium leaching is realized; the uranium leaching is realized under the condition of applying a direct current electric field.

[0038] An adsorption tower is arranged on the liquid passage, and the adsorption tower is used for adsorbing uranium in the leaching solution obtained through the uranium leaching.

[0039] If not specially specified, the raw materials used in the application are preferably commercially available products.

[0040] In the application, the ore-bearing layer preferably comprises a mineral body and underground water, and the mineral body is preferably a sandstone type uranium deposit.

[0041] In the application, the underground water in the ore-bearing layer is extracted through the liquid extraction well, and the extracted underground water is re-injected into the ore-bearing layer through the liquid injection well, so that the circulation flow of the underground water is realized through the liquid passage, and the ore-bearing layer is dredged.

[0042] In the application, the time for dredging is preferably 30-40 days. The application does not make specific limitation on the rate of the circulation flow of the underground water in the process of dredging, and parameters well known by those skilled in the art can be used. In the application, the dredging can realize the dredging of the ore-bearing layer.

[0043] In the application, the ore-bearing layer is dredged first, so as to provide a basic condition for the contact between the ore leaching agent and the mineral body in the ore-bearing layer.

[0044] After dredging, oxygen and carbon dioxide are added into the underground water in the ore-bearing layer, and the circulation flow of the underground water is continuously realized through the liquid passage, so that the micro-acid pretreatment is realized; the micro-acid pretreatment is realized under the condition of applying a direct current electric field.

[0045] In the application, the injection pressure of the oxygen is preferably 1-2 MPa, and is more preferably 1 MPa, 1.5 MPa or 2 MPa; and the injection pressure of the carbon dioxide is preferably 1-3 MPa, and is more preferably 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa or 3 MPa.

[0046] The rate of the circulation flow of the groundwater during the slightly acidic pretreatment is not particularly limited in the present application, and can be determined using parameters well known to those skilled in the art. In the present application, the strength of the direct current electric field during the slightly acidic pretreatment is preferably 0.1-0.4 V / cm, and more preferably 0.1 V / cm, 0.2 V / cm, 0.3 V / cm or 0.4 V / cm. The time of the slightly acidic pretreatment is not particularly limited in the present application, as long as the obtained leaching solution is in a slightly acidic environment, and the pH value of the slightly acidic environment is preferably 6.0-6.5, and more preferably 6 or 6.5.

[0047] In the present application, CO2 and O2 are injected into the groundwater, and the slightly acidic pretreatment is performed under the condition of applying a direct current electric field to dissolve the metallic uranium from the ore body. The application of the direct current electric field can enhance ion migration, accelerate the oxidation and dissolution process of the uranium, and at the same time, optimize the slightly acidic environment, maintain the weak acidic condition, and promote the continuous dissolution of the uranium.

[0048] After the slightly acidic pretreatment, the present application injects carbon dioxide and a bacterial solution into the groundwater containing the ore bed, and continues the circulation flow of the groundwater through the liquid passage to achieve uranium leaching. The uranium leaching is performed under the condition of applying a direct current electric field. The bacterial solution has a carbonate dissolution function.

[0049] In the present application, the injection pressure of the carbon dioxide is preferably 1-3 MPa, and more preferably 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa or 3 MPa; and the injection time is preferably 105-120 min, and more preferably 105 min, 110 min, 115 min or 120 min.

[0050] In the present application, the bacterial solution is preferably an ATCC55618 actinobacillus succinogenes solution; and the concentration of the bacterial solution is at least 1.0 x 10 8 / mL, and further preferably 1.0 x 10 8 -10 x 10 8 / mL. In the present application, the injection amount of the bacterial solution is preferably 10-20 L / (m 2 ·h), and more preferably 10 L / (m 2 ·h), 11 L / (m 2 ·h), 12 L / (m 2 ·h), 13 L / (m 2 ·h), 14 L / (m 2 ·h), 15 L / (m 2 ·h), 16 L / (m 2 ·h), 17 L / (m 2 ·h), 18 L / (m 2• h), 19 L / (m 2 • h) or 20 L / (m 2 • h).

[0051] In the present application, the preparation method of the bacterial solution preferably comprises: mixing the commercially available ATCC55618 succinic acid-producing actinobacillus with water to obtain the bacterial solution. In the present application, after the commercially available ATCC55618 succinic acid-producing actinobacillus is mixed with water, the present application preferably further comprises domestication, which is preferably successive electro-domestication; the operation of the successive electro-domestication in the present application is not specifically limited, as long as the strain can be adapted to the use environment in advance.

[0052] In the present application, the bacterial solution with carbonate corrosion function and carbon dioxide are introduced into the ore body after the pre-treatment of micro-acid; the bacterial solution with carbonate corrosion function can corrode the carbonate in the ore body, further corrode the insoluble U 4+ Oxidation to soluble U 6+ These U 6+ form a high-solubility uranyl carbonate complex with the injected CO2, thereby increasing the concentration of metallic uranium in the leaching solution and the leaching efficiency, and shortening the leaching time, while being environmentally friendly. In addition, the application of a direct current electric field can also enhance the metabolic activity of the bacteria in the bacterial solution, accelerate the corrosion of carbonate minerals, further improve the leaching efficiency, and achieve high-efficiency leaching under low acidity and low energy consumption, reducing the use of chemical reagents and environmental pollution.

[0053] In the present application, the intensity of the direct current electric field during the uranium leaching process is preferably 0.1-0.4 V / cm, and more preferably 0.1 V / cm, 0.2 V / cm, 0.3 V / cm or 0.4 V / cm. By applying a direct current electric field, the efficiency and sustainability of in-situ leaching of uranium are significantly improved. The direct current electric field enhances the activity of the bacteria in the bacterial solution, promotes the oxidation of U 4+ to U 6+ , and accelerates the dissolution of heavy metals. Under the action of the direct current electric field, the bacteria in the bacterial solution can directly use the cathode as an electron donor to improve the metabolic activity. At the same time, the direct current electric field inhibits the formation of a passivation layer on the surface of the ore body, increases the contact area between the leaching agent and the ore body, and promotes the continuous leaching of uranium. In addition, the direct current electric field increases the diversity and abundance of microbial communities, optimizing the microbial-mediated corrosion and oxidation processes. The direct current electric field also accelerates the migration and diffusion of uranium ions, reduces the chemical reaction activation energy, speeds up the oxidation and dissolution of uranium, while maintaining a weak acidic environment, reducing the use of strong acid reagents. The direct current electric field also enhances the corrosion of carbonate minerals, releasing more uranium and further improving the leaching efficiency. Compared with traditional strong acid leaching, the application of a direct current electric field achieves high-efficiency leaching under low acidity and low energy consumption, reduces the use of chemical reagents and environmental pollution, and reduces operating costs.

[0054] The present application does not specifically limit the rate of the circulation flow of the groundwater in the process of the uranium leaching, and the parameters known to those skilled in the art can be used.

[0055] In the present application, the liquid passage is provided with an adsorption tower for adsorbing the uranium in the leaching solution obtained by the uranium leaching.

[0056] In the present application, when the concentration of the uranium in the leaching solution is lower than 5 mg / L, the uranium leaching process is preferably stopped.

[0057] In the present application, the ore-bearing layer is first dredged to provide a basic condition for the contact between the ore leaching agent and the ore body in the ore-bearing layer; then, CO2 and O2 are injected into the groundwater, and the micro-acid pretreatment is carried out under the condition of applying a direct current electric field to dissolve the metallic uranium from the ore body. 4+ oxidized to soluble U 6+ . These U 6+ form high-solubility uranyl carbonate complexes with the injected CO2, thereby increasing the concentration of the metallic uranium in the leaching solution and the leaching efficiency, and shortening the leaching time, while being environmentally friendly. At the same time, the present application also increases the activity of the bacteria in the bacterial solution by using the direct current electric field. Under the action of the direct current electric field, the bacteria in the bacterial solution can directly use the cathode as an electron donor to obtain a higher bacterial concentration. It also limits the formation of the passivation layer on the surface of the ore body to a certain extent, increases the microbial diversity and relative abundance of the target microorganisms in the entire community, and increases the contact area between the leaching agent and the ore body in the ore-bearing layer in the subsequent uranium leaching process, thereby promoting the continuous uranium leaching and further improving the uranium leaching efficiency. The method of the present application not only improves the uranium mining efficiency, but also reduces the impact on the environment, thereby providing a more environmentally friendly and efficient scheme for the mining of uranium mines.

[0058] The present application also provides a system for in-situ leaching of uranium mining, comprising a liquid passage and an electric passage.

[0059] The liquid passage comprises a liquid pumping well arranged in the ore body, an adsorption tower and a liquid injection well arranged in the ore body connected in sequence; the liquid inlet of the liquid pumping well and the liquid outlet of the liquid injection well are in contact with the underground water in the ore-bearing layer; the liquid outlet of the liquid pumping well and the carbon dioxide inlet are arranged; the oxygen inlet is arranged between the adsorption tower and the liquid inlet of the liquid injection well; the bacteria liquid inlet is arranged between the oxygen inlet and the liquid inlet of the liquid injection well;

[0060] The electric passage comprises a positive electrode, a negative electrode and a direct current power supply; the positive electrode and the negative electrode are arranged in the underground water of the ore-bearing layer, and the positive electrode and the negative electrode are arranged vertically in parallel; the positive electrode is located at the liquid inlet of the liquid pumping well, and the direct current power supply is located on the ground; the negative electrode is located at the liquid outlet of the liquid injection well; the positive electrode, the negative electrode and the direct current power supply are connected by wires.

[0061] Figure 1 The system for in-situ leaching of uranium provided by the present application is shown in the schematic diagram, and the following will be described in detail Figure 1 The system for in-situ leaching of uranium provided by the present application is shown in the schematic diagram, and the following will be described in detail

[0062] The system for in-situ leaching of uranium provided by the present application comprises a liquid passage; the liquid passage comprises a liquid pumping well 2 arranged in the ore body, an adsorption tower 13 and a liquid injection well 1 arranged in the ore body connected in sequence; the liquid injection well 1 is preferably arranged in a first casing pipe 7, and the liquid pumping well 2 is preferably arranged in a second casing pipe 8; the liquid inlet of the liquid pumping well 2 and the liquid outlet of the liquid injection well 1 are in contact with the underground water in the ore-bearing layer; the liquid outlet of the liquid pumping well 2 and the carbon dioxide inlet 16 are arranged between the adsorption tower 13; the carbon dioxide inlet 16 is preferably connected with a carbon dioxide fluid storage tank for carbon dioxide fluid injection; the oxygen inlet 17 is arranged between the adsorption tower 13 and the liquid inlet of the liquid injection well 1, and the oxygen inlet 17 is preferably in communication with an oxygen storage tank for oxygen injection; the bacteria liquid inlet 18 is arranged between the oxygen inlet 17 and the liquid inlet of the liquid injection well 1, and the bacteria liquid inlet 18 is in communication with a bacteria liquid storage tank 11 for bacteria liquid injection. In the present application, a submersible pump 12 is preferably arranged on the liquid passage, and the submersible pump 12 is preferably located at the liquid inlet of the liquid pumping well for pumping the underground water to the liquid passage to realize the circulating flow of the underground water. In the present application, a first filter 9 and a second filter 10 are preferably further arranged in the liquid passage; the first filter 9 is located in the underground water at the bottom end of the liquid injection well 1 to purify the underground water; and the second filter 10 is located in the underground water at the bottom end of the liquid pumping well 1 to purify the underground water. In the present application, a gas release valve 15 is preferably further arranged on the liquid passage, and the gas release valve 15 is preferably arranged between the liquid outlet of the liquid pumping well 2 and the carbon dioxide inlet 16 to release the gas in the liquid.

[0063] The in-situ leaching uranium mining system comprises an electric channel; the electric channel comprises a positive electrode 4, a negative electrode 3 and a direct current power supply 5; the positive electrode 4 and the negative electrode 3 are arranged in the underground water of the ore-bearing layer, and the positive electrode 4 and the negative electrode 3 are arranged vertically and in parallel; the positive electrode 4 is located at the liquid inlet of the liquid pumping well 2, and the direct current power supply 5 is located on the ground; the negative electrode 3 is located at the liquid outlet of the liquid injection well 1; the positive electrode 4, the negative electrode 3 and the direct current power supply 5 are connected through a wire 6. In the application, a multimeter 14 is preferably arranged between the direct current power supply 5 and the positive electrode 4, and the multimeter 14 is located on the ground.

[0064] The in-situ leaching uranium mining method of the application will be described in detail below in combination with the system of the application, and specifically: Figure 1

[0065] The gas release valve 15, the carbon dioxide inlet 16, the oxygen inlet 17 and the bacteria liquid inlet 18 on the liquid channel are closed;

[0066] The submersible pump 12 is opened, the underground water in the ore-bearing layer is pumped through the liquid pumping well 2, and the pumped underground water is injected into the ore-bearing layer through the liquid injection well 1, the circulation of the underground water is carried out through the liquid channel, and the ore-bearing layer is dredged;

[0067] After the dredging is completed, the carbon dioxide inlet 16 and the oxygen inlet 17 are opened, oxygen and carbon dioxide are injected into the underground water of the ore-bearing layer, the circulation of the underground water is continued through the liquid channel, and the micro-acid pretreatment is realized; at the same time, the electric channel is opened, and a direct current electric field is applied; during the micro-acid pretreatment, the gas release valve 15 is opened to ensure the safe and stable operation of the pipeline of the liquid injection well 1 and the pipeline of the liquid pumping well 2;

[0068] After the micro-acid pretreatment, carbon dioxide is injected into the underground water of the ore-bearing layer through the carbon dioxide inlet 16, bacteria liquid is injected through the bacteria liquid inlet 18, the circulation of the underground water is continued through the liquid channel, and uranium leaching is realized; at the same time, the electric channel is kept open, and a direct current electric field is applied; during the uranium leaching, the gas release valve 15 is opened to ensure the safe and stable operation of the pipeline of the liquid injection well 1 and the pipeline of the liquid pumping well 2;

[0069] The uranium in the leaching solution of the uranium leaching is adsorbed by the adsorption tower 13.

[0070] The in-situ leaching uranium mining method and system provided by the application will be described in detail below in combination with the embodiments, but they should not be understood as limitations on the protection scope of the application.

[0071] Embodiment 1

[0072] ​Preparation of the bacterial solution: the ATCC55618 succinic acid-producing actinobacillus was subjected to successive generations of electric domestication to adapt the ATCC55618 succinic acid-producing actinobacillus to the use environment, and the concentration of the ATCC55618 succinic acid-producing actinobacillus in the obtained bacterial solution was 1×10 8

[0073] A method for in-situ leaching of uranium, which is carried out in the schematic diagram shown in the figure, comprises the following steps: Figure 1

[0074] S1, dredging of the ore-bearing layer: the underground water in the ore-bearing layer is extracted through the liquid extraction well, and the extracted underground water is re-injected into the ore-bearing layer through the liquid injection well, the circulation flow of the underground water is carried out through the liquid passage, and the dredging of the ore-bearing layer is realized; the dredging time is 30 days.

[0075] S2, micro-acid pretreatment: after the dredging is completed, oxygen (the injection pressure of the oxygen is 1 MPa) and carbon dioxide (the injection pressure of the carbon dioxide is shown in Table 1) are injected into the underground water in the ore-bearing layer, the circulation flow of the underground water is continuously carried out through the liquid passage, and the micro-acid pretreatment is realized, until the underground water is in a micro-acid environment, i.e., the pH is 6; the micro-acid pretreatment is carried out under the condition that a direct current electric field (the intensity is 0.2 V / cm) is applied.

[0076] S3, uranium leaching: after the micro-acid pretreatment, carbon dioxide (the injection pressure is shown in Table 1, and the injection time is 100 min) and the bacterial solution (the injection amount is 15 L / (m 2 ·h) are injected into the underground water in the ore-bearing layer, the circulation flow of the underground water is continuously carried out through the liquid passage, and the uranium leaching is realized; the uranium leaching is carried out under the condition that a direct current electric field (the intensity is 0.2 V / cm) is applied; when the concentration of uranium in the leaching solution is reduced to less than 5 mg / L, the leaching process is stopped.

[0077] In the adsorption tower, the adsorption material is an adsorption resin, and the adsorption resin is a D201 strong basic anion exchange resin; the mass exchange capacity of the D201 macroporous strong basic anion exchange resin is ≥3.7 mmol / g, the volume exchange capacity is ≥1.2 mmol / ml, the particle size range is 0.7-1.6 mm, the wet true density is 1.06-1.10 g / mL, the wet apparent density is 0.65-0.73 g / mL, and the sphericity rate is ≥90%.

[0078] In the process of S3 uranium leaching, the carbon dioxide injection pressure and the corresponding uranium leaching efficiency are shown in Table 1.

[0079] Table 1: Leaching efficiency under different carbon dioxide injection pressures

[0080] No. Injection pressure of CO2 (MPa) Extraction efficiency (%) 1 1 43.5 2 2 55.2 3 3 57.6

[0081] ​​From the results of Table 1, it can be seen that when the injection pressure of CO2 is between 1-2 MPa, the leaching efficiency of uranium increases with the increase of the injection pressure. At 2 MPa, the leaching efficiency of uranium reaches the highest value of 55.2%. However, when the injection pressure exceeds 2 MPa, the increase of the leaching efficiency of uranium is significantly reduced, and especially when the injection pressure exceeds 2 MPa, the leaching efficiency of uranium hardly changes. Such an excessively high injection pressure not only has limited effect on improving the leaching efficiency, but also significantly increases the maintenance cost and technical difficulty of the pipeline and equipment in the mining process. Therefore, from the comprehensive consideration of economic cost and technical difficulty, 2 MPa is selected as the optimal injection pressure of CO2. This selection can not only ensure a higher leaching efficiency of uranium, but also effectively control the operating cost and technical complexity, thereby providing an important reference for efficient mining of uranium ore.

[0082] Example 2

[0083] Compared with Example 1, in the process of leaching of S3 uranium, the injection pressure of carbon dioxide is determined as 2 MPa; the difference lies in that the injection time of CO2 in the process of leaching of S3 uranium is changed according to Table 2, and other operations are the same as above, which will not be repeated here. The specific condition parameters and the leaching efficiency of uranium are shown in Table 2.

[0084] Table 2 Leaching efficiency under different injection time of carbon dioxide

[0085] No. CO2injection time (min) Extraction efficiency (%) 1 80 48.7 2 100 53.3 3 110 56.5 4 130 51.8

[0086] From Table 2, it can be seen that when the injection time of CO2 is between 80-110 min, the leaching efficiency of uranium increases, but the amplitude is not significant. When the injection time reaches 110 min, the leaching efficiency has tended to the maximum value, and then with the continuous extension of the injection time, the leaching efficiency of uranium in the ore body does not increase significantly, but decreases slightly after 110 min. This phenomenon is due to if the injection time is too short (less than 100 min), the uranium elements in the ore body cannot be fully dissolved, resulting in a low leaching efficiency. When the injection time exceeds 110 min, the pH value of the solution increases, and the hydrolysis of Fe 3+ in the ore body is enhanced, and the amount of Fe colloid generated increases, which will adsorb the uranium elements dissolved in the leaching solution, thereby leading to the decrease of the leaching efficiency of uranium ore body.

[0087] Example 3

[0088] Compared with Example 1, in the process of leaching of S3 uranium, the injection pressure of carbon dioxide is determined as 2 MPa, and the injection time is 110 min; the difference lies in that the direct current field strength is changed according to Table 3, and other operations are the same as above, which will not be repeated here. The specific condition parameters and the leaching efficiency of uranium are shown in Table 3.

[0089] Table 3 Leaching efficiency under different direct current electric field intensity

[0090] No. Direct current field strength (V / cm) Extraction efficiency (%) 1 0 46.2 2 0.2 54.5 3 0.4 57.1 4 0.8 48.4

[0091] As can be seen from Table 3, with the increase of direct current electric field intensity, the leaching efficiency presents a trend of first increasing and then decreasing. When the applied voltage is 0 V / cm, the leaching efficiency is 46.2%, and with the increase of direct current electric field intensity to 0.2 V / cm and 0.4 V / cm, the leaching efficiency is increased to 54.5% and 57.1% respectively, reaching the highest value. However, when the direct current electric field intensity is further increased to 0.8 V / cm, the leaching efficiency is decreased to 48.4%. This phenomenon can be attributed to the dual effect of direct current electric field intensity on bacterial growth and reproduction. Appropriate direct current electric field intensity can enhance the metabolic capacity of bacteria, promoting the bioleaching of metal ions. This is because the direct current electric field intensity can increase the permeability of bacterial cell membrane, thereby improving the uptake efficiency of nutrients and metabolic activity, ultimately leading to the increase of leaching efficiency. However, when the direct current electric field intensity is too high, the surface hydrophobicity and surface charge of bacteria increase, resulting in an increase in the number of intermediate products such as ·OH and H2O2 generated in the hydrolysis process. These strong oxidizing intermediate products have an inhibitory effect on bacterial cells, which can damage the structure and function of bacterial cell membrane, inhibit the growth and reproduction of bacteria, and thus lead to the decrease of leaching efficiency. Therefore, in practical application, appropriate direct current electric field intensity should be carefully selected to achieve the best bioleaching effect. Appropriate direct current electric field intensity not only can promote the leaching of metals, but also can avoid excessive inhibition of bacteria, ensuring the efficiency and stability of the entire bioleaching process.

[0092] Example 4

[0093] Compared with Example 1, in the process of S3 uranium leaching, the carbon dioxide injection pressure was determined as 2 MPa, the injection time was 110 min, the direct current electric field intensity was 0.4 V / cm, the injection amount of bacterial solution was changed according to Table 4, and other operations were the same except the above differences, which will not be repeated here. The specific condition parameters and the leaching efficiency of uranium are shown in Table 4.

[0094] Table 4 Leaching efficiency under different injection amounts of bacterial solution

[0095] No. Bacterial solution injection amount (L / (m 2 ·h)) Extraction efficiency (%) 1 0 42.4 2 5 46.3 3 10 54.9 4 20 49.7

[0096] As can be seen from Table 4, changing the injection amount of bacterial solution in step S3 can have a significant impact on the in-situ leaching efficiency of uranium. When the injection amount of bacterial solution is 0 L / (m2·h), the leaching efficiency is low, only 42.4%. With the increase of injection amount of bacterial solution, the leaching efficiency gradually increases, reaching 10 L / (m 2• h) the leaching efficiency was the highest, reaching 54.9%. However, when the injection amount of bacterial solution was further increased to 20 L / (m 2 • h), the leaching efficiency decreased to 49.7%. This phenomenon indicates that appropriate injection amount of bacterial solution can enhance the activity and metabolic capacity of bacteria, thereby improving the leaching efficiency. In the process of uranium leaching, the bacteria in the bacterial solution improve the porosity and permeability of the ore body by dissolving the carbonate, improve the contact range of the leaching agent with the ore body, and then oxidize the insoluble U 4+ to soluble U 6+ and CO3 2- forms a high-solubility uranyl carbonate complex. This method not only improves the leaching efficiency and concentration of uranium, but also effectively utilizes the natural ingredients in the ore body, achieving efficient use of resources. However, excessive injection amount of bacterial solution may lead to high concentration of bacteria in the leaching solution, increased resource competition, and enhanced mutual inhibition effect between bacteria. In addition, excessive injection of bacterial solution may also cause changes in the pH value of the leaching solution, affecting the normal metabolism of bacteria and the solubility of uranium. Therefore, controlling the addition amount of bacterial solution within an appropriate range is crucial for optimizing the leaching efficiency of uranium.

[0097] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A method for in-situ leaching of uranium, characterized in that: The following steps are involved: Extract groundwater from the mineral-bearing layer through the pumping well, and inject the extracted groundwater back into the mineral-bearing layer through the injection well. The groundwater circulates through the liquid pathway to achieve dredging of the mineral-bearing layer. After dredging, oxygen and carbon dioxide are injected into the groundwater containing the mineral layer, and the groundwater continues to circulate through the liquid pathway to achieve slightly acidic pretreatment; The slightly acidic pretreatment is carried out under the condition of applying a direct current electric field; After slight acid pretreatment, carbon dioxide and bacterial solution are injected into the groundwater containing the mineral layer, and the groundwater continues to circulate through the liquid path to achieve uranium leaching; the uranium leaching is carried out under the condition of applying a direct current electric field; the bacterial solution has a carbonate dissolution function; An adsorption tower is provided on the liquid passage, and the adsorption tower is used to adsorb uranium in the leachate obtained by uranium leaching.

2. The method according to claim 1, characterized in that The dredging time is 30 to 40 days.

3. The method according to claim 1, characterized in that During the slightly acidic pretreatment, the injection pressure of the oxygen is 1-2 MPa, and the injection pressure of the carbon dioxide is 1-3 MPa.

4. The method according to claim 1 or 3, characterized in that During the slight acid pretreatment, the intensity of the DC electric field is 0.1 to 0.4 V / cm.

5. The method according to claim 1, wherein During the uranium leaching process, the injection pressure of the carbon dioxide is 1-3 MPa, and the injection time is 105-120 minutes.

6. The method according to claim 1, characterized in that The bacterial solution is ATCC55618 succinic acid-producing actinomycetemcomitans solution; the concentration of the bacterial solution is at least 1.0×10 8 The injection volume of the bacterial solution is 10-20 L / (m 2 ·h).

7. The method according to claim 1, 5 or 6, characterized in that: During the uranium leaching process, the intensity of the DC electric field is 0.1-0.4 V / cm.

8. The method according to claim 1, characterized in that When the uranium concentration in the leaching solution drops below 5 mg / L, the uranium leaching process is stopped.

9. The method according to claim 1, characterized in that The adsorption material in the adsorption tower is an adsorption resin, which is a D201 strong basic anion exchange resin. The D201 strong basic anion exchange resin has a mass exchange capacity of ≥3.7 mmol / g, a volume exchange capacity of ≥1.2 mmol / ml, a particle size range of 0.7 to 1.6 mm, a wet true density of 1.06 to 1.10 g / mL, a wet apparent density of 0.65 to 0.73 g / mL, and an infiltration and grinding ball rate of ≥90%.

10. A system for in-situ leaching of uranium, characterized in that: including liquid pathways and electrical pathways; The liquid passage comprises a liquid extraction well, an adsorption tower and a liquid injection well provided in the ore body, which are connected in sequence; the liquid inlet of the liquid extraction well and the liquid outlet of the liquid injection well contact the groundwater in the ore-bearing layer; A carbon dioxide inlet is provided between the liquid outlet of the liquid extraction well and the adsorption tower; An oxygen inlet is provided between the adsorption tower and the liquid inlet of the injection well; a bacterial liquid inlet is provided between the oxygen inlet and the liquid inlet of the injection well; The electrical path includes a positive electrode, a negative electrode and a DC power supply; the positive electrode and the negative electrode are placed in the groundwater of the mineral-bearing layer, and the positive electrode and the negative electrode are arranged vertically and in parallel; the positive electrode is located at the liquid inlet of the pumping well, and the DC power supply is located on the ground; the negative electrode is located at the liquid outlet of the injection well; the positive electrode, the negative electrode and the DC power supply are connected by wires.

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