A method for extracting and separating uranium from sandstone uranium ore by one-step electric current

Abstract

The present invention discloses a method for extracting and separating uranium from sandstone uranium ore in one step by applying electricity. The method comprises: using an activation leaching agent to adjust the pH of the activation environment to ≤3, thereby converting the uranium in the sandstone uranium ore into positively charged uranyl and its complex; applying a DC electric field with a voltage gradient of 0.1 to 2 V / cm between anode and cathode electrodes, causing the uranium to migrate toward the cathode chamber under the action of the electric field and selectively reduce on the cathode, where it is reduced to a low-valent, insoluble uranium-containing substance that precipitates on the cathode surface by gaining electrons. The present invention uses activation leaching to form only positively charged uranium ions and their complexes, and electrophysical effects such as electromigration and electroosmosis cause the uranium to move toward the cathode in a directional manner, thereby achieving the extraction of uranium from the sandstone uranium ore; at the same time, through electrochemical effects such as reduction caused by gaining electrons on the surface of the cathode conductive plastic electrode, the soluble uranium is reduced and fixed on the surface of the cathode conductive plastic electrode, thereby achieving the one-step separation and purification of the uranium.

Description

Technical Field

[0001] The invention relates to a method for purifying uranium elements, in particular to a method for extracting and separating uranium elements from sandstone uranium ore by electrifying in one step. Background Art

[0002] Among sandstone uranium deposits, numerous are difficult to mine using in-situ leaching methods. These deposits typically exhibit poor permeability, high carbonate and argillaceous content, low ore grade, and complex geological and hydrogeological conditions. Uranium minerals in uranium ores are characterized by complex occurrences, high levels of tetravalent uranium, close symbiosis with gangue minerals, high concentrations of organic matter and carbonate minerals, poor permeability and filtration properties, and difficulty in solid-liquid separation, making them difficult to process.

[0003] Traditional uranium leaching methods include acid leaching, alkaline leaching, CO2+O2 leaching, and microbial leaching. Acid leaching often uses H2SO4 as a leaching agent, but the leaching process is prone to precipitate formation, which can clog the leaching channels. Alkaline leaching often uses Na2CO3 as a leaching agent, which selectively dissolves metals and is difficult to dissolve elements such as Ca, Mg, Fe, and Al. Alkaline leaching is generally slow and requires high temperatures. The recently emerging CO2+O2 leaching method, while beneficial for the development of low-grade uranium ores, is only suitable for ore bodies with a certain degree of permeability. Microorganisms such as Thiobacillus ferrooxidans have weak adaptability to the environment, and these microbial leaching methods have high environmental requirements. All of these leaching methods are difficult to achieve efficient uranium extraction in low-permeability sandstone uranium ores, low-grade sandstone uranium ores with diverse uranium occurrence conditions, complex inter-mineral interface relationships, and high water content.

[0004] Electromining is a new mining technology. Its main mechanism is to promote the migration and enrichment of dissolved charged ions and their complexes in the ore through electromigration and electroosmosis. The existing related patents are as follows:

[0005] Chinese patent CN108411130A discloses a method for electrically assisted enhanced leaching of uranium from low-grade uranium ore. The method uses dilute sulfuric acid with a concentration of 35-60 g / L as the leaching solution, metallic iron as the anode, and graphite or metallic iron as the cathode. Under the action of direct current, the anode iron gradually dissolves and converts into trivalent iron ions, providing an oxidant for the leaching system, promoting the conversion of insoluble tetravalent uranium to easily soluble hexavalent uranium, and finally collecting the uranium-containing leachate.

[0006] Chinese patent CN109609788A discloses a method for separating uranium from uranium ore pulp using an electrodialysis method. The method comprises using a sulfuric acid solution with a mass concentration of 48-55% as a leaching agent, stirring and leaching a uranium-containing ore sample with the leaching agent to obtain a uranium-containing ore pulp. The uranium-containing ore pulp is then subjected to electrodialysis to separate uranium, and finally a uranium-enriched solution and tailings are obtained.

[0007] Chinese patent CN114658407A discloses an electric in-situ leaching apparatus and method for uranium mining. Uranium ore is placed between an injection well and an extraction well; a negative electrode is placed in the injection well; a positive electrode is placed in the extraction well; oxygen and hydrogen peroxide are used as oxidants, and sulfuric acid and CO2 solutions are used as leaching agents; a leaching solution is injected from the injection well, extracted from the extraction well after passing through the uranium ore, and the leaching solution is collected and then uranium is extracted.

[0008] The leaching agents used in the above patents CN108411130A, CN109609788A and CN117564070A, such as sulfuric acid, citric acid and oxalic acid, usually need to be used in large quantities. The common problem of these leaching agents is that they cannot unify the uranium element into particles with the same electrical properties. In this case, positively charged UO2 2+ , negatively charged UO2(X)2 2- 、UO2(X)3 4- (X is SO₄ or CO₃) particles of different charges. Due to the different charge properties of these ions, their migration directions in the electric field are also different, making it impossible to achieve directional and controllable collection of uranium. In addition, if H₂SO₄ is used, insoluble matter may be generated, blocking the leaching channel and thus affecting the uranium leaching efficiency.

[0009] In addition, the final products obtained are all uranium-containing leachates, which need to be further processed to remove impurities and refine the uranium. At present, the composition of uranium ore leachates is complex, often containing a variety of metal ion impurities, which are difficult to separate; the leachates contain uranium-containing particles in various forms, such as positively charged UO2 2+ , negatively charged UO2(X)2 2- Particles with different charges will require different purification methods, and the impurity removal process is more complicated; the more commonly used extraction method also faces problems such as strong selectivity of the extraction agent, high cost, easy emulsification, and regeneration and processing.

[0010] Therefore, there is an urgent need for a more efficient and convenient one-step method for extracting and separating uranium.

[0011] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the Invention

[0012] The present invention aims to provide a method for extracting and separating uranium from sandstone uranium ore in one step by applying electricity, thereby solving the problem that existing electric leaching uranium mining technology cannot achieve the enrichment of uranium with particles of the same charge property on a fixed electrode and the simultaneous separation and purification in one step. The method of the present invention can make the uranium in the sandstone uranium ore form only positively charged ions and complexes, thereby achieving directional migration and enrichment of uranium by utilizing electrophysical effects such as electromigration and electroosmosis, and can efficiently and selectively reduce oxidized high-valent uranium cations, which are ultimately reduced and fixed on the surface of a cathode conductive plastic electrode, thereby achieving the one-step extraction, separation and purification of uranium.

[0013] To achieve the above object, the present invention provides a method for extracting and separating uranium from sandstone uranium ore by applying electricity in one step, the method comprising:

[0014] Uranium activation: Using an activation leaching agent to adjust the pH of the activation environment to ≤3, the uranium element in the sandstone uranium ore is converted into positively charged uranyl and its complex; wherein the activation leaching agent is a mixture of FeCl3 and a chlorine-containing inorganic acid;

[0015] Electric field drive: The activated sandstone uranium ore is introduced into a DC electric field. A DC electric field with a voltage gradient of 0.1-2 V / cm is applied between the cathode and cathode electrodes. This causes the positively charged uranyl and its complexes to undergo electrophysical effects such as electromigration and electroosmosis under the action of the electric field, leading to their directionally enriched concentration in the cathode chamber.

[0016] Electrode selective reduction and fixation of uranium: Both the anode and cathode electrodes are conductive plastic electrodes. The surface of the cathode conductive plastic electrode selectively reduces the positively charged uranium element, and is electrochemically reduced to a low-valent insoluble uranium-containing substance (such as UO2) and precipitated on the surface of the cathode conductive plastic electrode. Other impurity metal ions will not precipitate on the surface of the cathode conductive plastic electrode through hydroxide. The uranium-containing precipitate collected on the surface of the cathode conductive plastic electrode has a very low impurity rate.

[0017] The present invention combines uranium element activation, electric drive and selective reduction technologies together. The uranium element in the sandstone uranium ore is converted into a positively charged substance, so that the uranium moves toward the cathode conductive plastic electrode under the action of an electric field. The uranium is reduced by electric induction at the cathode conductive plastic electrode, and the uranium is converted into a low-valent insoluble uranium-containing substance that is precipitated on the surface of the cathode conductive plastic electrode. Other impurity metal ions will not precipitate on the surface of the cathode conductive plastic electrode through hydroxide, thereby enriching uranium.

[0018] During the activation process of the present invention, part of the insoluble tetravalent uranium in the ore body is gradually converted into soluble hexavalent uranium, such as UO2 2+ , a small amount of UO2 2+ With Cl - UO2Cl formed by complexation+ and UO2 2+ (UO2)2OH produced by hydrolysis 3+ 、(UO2)2(OH)2 2+ 、(UO2)3(OH)4 2+ 、(UO2)3(OH) 5+ Positively charged particles.

[0019] Uranium is converted into low-valent, insoluble uranium-containing substances as follows:

[0020] UO2 2+ (aq)+2e - →UO2(s)

[0021] UO2Cl + (aq)+2e - →UO2(s)+Cl - (aq)

[0022] Under the action of the electric field, uranyl ions are preferentially reduced. The reduction potential of uranyl ions and their uranyl chloride complex cations is higher than that of other metal ions such as potassium, sodium, calcium, and magnesium, making them more easily reduced. 3+ Not used up by the activation process, but precipitated Fe 3+ The pH is between 1.5 and 3.5, so some Fe 3+ It will be hydrolyzed in the cathode liquid and precipitated into the cathode liquid; although Fe 3+ The reduction potential is relatively high, leaving unhydrolyzed Fe 3+ Will precede UO2 2+ Reduction to Fe 2+ , but the precipitation of Fe 2+ The pH needs to be between 7.0 and 9.0, so the iron element is not easily adsorbed and fixed by the cathode plate in the system of the method of the present invention.

[0023] In addition, other metal elements are not easy to produce hydroxide precipitation under acidic conditions. The pH required for precipitation of other metal elements is as follows: Al 3+ :pH 4.5~6.0;Cu 2+ :pH 6.0~8.0;Zn 2+ :pH 7.0~9.0;Ni 2+ :pH 8.0~9.5;Pb 2+ :pH 6.0~8.0;Mg 2+ :pH 10.5~12.0;Ca 2+ :pH 12.0~13.0.

[0024] Therefore, in the system of the present invention, only the electro-reduced tetravalent uranium precipitate is selectively retained on the cathode conductive plastic electrode, thereby achieving the purpose of removing impurities and purifying uranium elements.

[0025] Preferably, the voltage gradient is 0.1-0.5 V / cm. The impurity rate of the uranium-containing precipitate collected on the surface of the cathode conductive plastic electrode is very low, especially when the voltage gradient does not exceed 0.5 V / cm, the impurity rate is as low as less than 5%.

[0026] Preferably, the solid-liquid ratio of the sandstone uranium ore to the activated leaching agent is 1 kg: 1~10 L.

[0027] Preferably, the solid-liquid ratio of the sandstone uranium ore to the activated leaching agent is 1 kg: 5~10 L.

[0028] Preferably, the pH of the activation leaching agent is 0.5-3.

[0029] Preferably, the pH of the activation leaching agent is 0.5-1.

[0030] Preferably, the concentration of FeCl3 in the activation leaching agent is 10-20 g / L.

[0031] Preferably, the chlorine-containing inorganic acid is selected from any one or more of HCl, HClO and HClO4. For example, the present invention selects HCl+FeCl3 as the activation leaching agent, which greatly reduces the amount of leaching agent. FeCl3 can not only provide Fe 3+ UO2 in oxidized sandstone uranium ore can also provide Cl - HCl can provide Cl while maintaining the acidic pH environment of sandstone uranium ore. - Compared with H2SO4 leaching of uranium ore (Formula 1-3), using HCl+FeCl3 as the activation leaching agent can control the uranyl ions to react only with Cl - Forming a positively charged UO2Cl + Complex ions will not further cooperate with more chloride ions to form negatively charged complexes, reducing the supply of Cl - The amount of leaching agent used.

[0032]

[0033] Preferably, the sandstone uranium ore after adding the activation leaching agent is activated at a temperature of 0-40°C (in this temperature range, liquid is ensured to be present in the ore slurry) for 1-24 hours, and then a direct current with a voltage gradient of 0.1-2 V / cm is applied between the anode and cathode electrodes for 1-24 hours.

[0034] Preferably, the sandstone uranium ore is separated from the cathode conductive plastic electrode and the anode conductive plastic electrode by a cathode filter and an anode filter respectively to form a cathode chamber and an anode chamber, and the uranium element enters the cathode chamber through the cathode filter; or / and, the cathode filter and the anode filter are both nylon filters; or / and, the mesh size of the cathode filter and the anode filter are both 400 mesh.

[0035] The method of the present invention for extracting and separating uranium from sandstone uranium ore in one step by applying electricity solves the problem that existing electrokinetic leaching uranium mining technology cannot achieve the enrichment of uranium with particles of the same charged properties on a fixed electrode and simultaneous separation and purification in one step, and has the following advantages:

[0036] (1) Leaching and separation and purification: The method of the present invention can make the uranium element in the sandstone uranium ore form only positively charged ions and complexes by controlling the activation environment, thereby realizing the directional migration and enrichment of the uranium element by utilizing electrophysical effects such as electromigration and electroosmosis, having the effect of efficient and rapid enrichment, and reducing the amount of leaching agent used; under the action of an external electric field, the back adsorption is reduced and the uranium extraction efficiency is improved; by using a conductive plastic electrode as a cathode material, the oxidized high-valent uranium cations can be efficiently and selectively reduced, so that the high-valent uranium cations are selectively reduced on the surface of the cathode conductive plastic electrode, and the conductive plastic electrode can also The invention has the advantages of weak electrolysis, corrosion resistance, and low energy consumption. The invention controls the initial pH of the reaction system to be low and controls the electric field strength to weaken the electrolysis. Therefore, when the cathode conductive plastic electrode receives electrons and undergoes an electrically induced reduction, high-valent uranium cations can be reduced to low-valent insoluble uranium and fixed on the electrode surface, while other impurity metal ions will not be precipitated on the surface of the cathode conductive plastic electrode through hydroxides. At the same time, uranium has a high reduction potential and is reduced and fixed on the surface of the cathode conductive plastic electrode before other impurity metal ions, which is beneficial to improving the purity of the enriched uranium element and realizing the one-step electrical extraction and separation and purification of the uranium element.

[0037] (2) Reduce the amount of leaching agent: The present invention uses HCl + FeCl3 as the activation leaching agent, which greatly reduces the amount of leaching agent. FeCl3 can not only provide Fe 3+ UO2 in oxidized sandstone uranium ore can also provide Cl - HCl can provide Cl while maintaining the acidic pH environment of sandstone uranium ore. - The results show that compared with H2SO4 leaching of uranium ore, using HCl+FeCl3 as activation leaching agent can control the uranyl ions to only react with Cl - Forming a positively charged UO2Cl + Complex ions will not further cooperate with more chloride ions to form negatively charged complexes, reducing the supply of Cl - The amount of leaching agent used;

[0038] (3) Improved uranium enrichment efficiency: Under the action of the electric field, uranyl ions and uranyl complex cations, which contain positive uranium, undergo electrophysical interactions such as electromigration and electroosmosis, accelerating the enrichment of uranium toward the cathode conductive plastic electrode. In addition, due to the action of the external electric field, the adsorption of uranium-containing positive ions by mineral particles with negatively charged surfaces is weakened, further improving the dissolution efficiency of uranium. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention is a flow chart of a method for extracting and separating uranium from sandstone uranium ore by one step of electrification.

[0040] Figure 2 This is a schematic diagram of the method for extracting and separating uranium from sandstone uranium ore by applying electricity in one step according to the present invention.

[0041] Figure 3 This is a phase equilibrium analysis diagram of uranium ore at different pH values according to the present invention.

[0042] Label: power supply-1; cathode conductive plastic electrode-2; anode conductive plastic electrode-3; cathode chamber-4; anode chamber-5; cathode filter-6; anode filter-7; sandstone uranium ore-8. DETAILED DESCRIPTION

[0043] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0044] It should be noted that if specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer shall be followed. Reagents or instruments used without manufacturer's indication are all commercially available conventional products.

[0045] Throughout this disclosure, all features, such as values, amounts, amounts, and concentrations, specified in numerical ranges or percentage ranges are provided for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to encompass and specifically disclose all possible subranges and individual values within those ranges.

[0046] The features described in this disclosure may be combined in any manner, and as long as there are no conflicts between the combinations of these features, all possible combinations should be considered within the scope of this specification. Each feature disclosed in this specification may be replaced by any alternative feature that provides the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the features disclosed are merely general examples of equivalent or similar features.

[0047] At present, most of the leaching agents used to extract uranium from uranium ore are sulfuric acid. However, the use of sulfuric acid will also cause the presence of positively charged UO2. 2+ and negatively charged UO2(SO4)2 2- 、UO2(SO4)3 4- The different charged particles have different uranium migration directions under the influence of an electric field, making it impossible to achieve targeted and controllable uranium collection. Furthermore, the use of H₂SO₄ easily reacts to form insoluble matter, which blocks the leaching channels and reduces the uranium leaching rate. Furthermore, the final product is a uranium-containing leachate, which requires further processing to remove impurities and refine the uranium. The complexity of uranium leachate composition makes uranium purification currently difficult, complex, and costly.

[0048] Therefore, the present invention provides a method for extracting and separating uranium from sandstone uranium ore by one step of electric current. Figure 1 , combining uranium element activation, electric drive and selective reduction technology together, by converting the uranium element in the sandstone uranium ore into a positively charged one, so that it moves toward the cathode conductive plastic electrode 2 under the action of the electric field, and the uranium is reduced by electric induction at the cathode conductive plastic electrode 2, and the uranium is converted into a low-valent insoluble uranium-containing substance that is precipitated on the surface of the cathode conductive plastic electrode 2, while other impurity metal ions will not be precipitated on the surface of the cathode conductive plastic electrode 2 through hydroxide, thereby enriching uranium.

[0049] The present invention adopts FeCl3+HCl as leaching agent, combined with electric drive technology, FeCl3 can not only provide Fe 3+ UO2 in oxidized sandstone uranium ore can also provide Cl - To form UO2Cl with uranyl ion, which is still positively charged + Complex ions, HCl can provide Cl while ensuring the acidic pH environment of sandstone uranium ore -This results in the formation of only positively charged uranium complexes in the sandstone uranium ore, rather than a system where both anions and cations exist. This allows the electrophysical effects of electromigration and electroosmosis, such as the electromigration of positively charged uranium-containing particles such as uranyl ions and uranyl complex cations, upon application of an electric field, to more rapidly enrich uranium in the cathode chamber. Furthermore, under the action of the applied electric field, positively charged species migrate toward the cathode conductive plastic electrode 2, while negatively charged species migrate toward the anode conductive plastic electrode 3. This weakens the adsorption of positively charged uranium ions by negatively charged mineral particles, further increasing the leaching rate of uranium. Furthermore, the energization process not only accelerates liquid flow within the ore body but also oxidizes tetravalent uranium that was not oxidized during the activation process, further enhancing uranium dissolution. Under low pH and a suitable electric field, the positively charged uranium-containing particles enriched in the cathode chamber are selectively reduced by the cathode conductive plastic electrode, while other metallic impurity ions are not precipitated. The positively charged uranium-containing particles are then electrically reduced through charge transfer to obtain electrons, resulting in a high-purity uranium-containing precipitate on the surface of the cathode conductive plastic electrode 2.

[0050] By using the activated leaching agent of the present invention, the uranium element in the system exists in the form of UO2 2+ 、UO2 2+ With Cl - UO2Cl formed by complexation + and UO2 2+ (UO2)2OH produced by hydrolysis 3+ 、(UO2)2(OH)2 2+ 、(UO2)3(OH)4 2+ 、(UO2)3(OH) 5+ Positively charged particles.

[0051] In addition, the present invention has done the phase equilibrium analysis in the research, and the reaction system will produce uranyl hydroxide precipitation when the pH is 4.2, which affects the leaching of uranium element. Figure 3 In the technology of the present invention, although under acidic conditions, as the pH increases, the uranium content and impurity rate of the cathode electroreduction will be affected. Therefore, the present invention controls the pH of the acidic environment to be ≤3.

[0052] The conductive plastic electrodes used in the present invention are both electrically conductive and corrosion-resistant, making them particularly suitable for use in low-pH environments and enabling more economical purification of uranium from sandstone-type uranium deposits. For example, the EKG electrodes described in Chinese Patent CN118724422A may be used, but are not limited thereto. Other conductive plastic electrodes may also be used.

[0053] The following describes in detail the method for extracting and separating uranium from sandstone uranium ore by applying electricity in one step provided by the present invention through Examples 1 to 17.

[0054] Example 1

[0055] A method for extracting and separating uranium from sandstone uranium ore by applying electricity in one step, the method comprising:

[0056] A volume of 5 L of FeCl3+HCl with a pH of 3 was continuously introduced into 1 kg of sandstone uranium ore with a uranium concentration of 400 μg / g. The concentration of FeCl3 was 10 g / L and the pH was adjusted by HCl. During the activation process, some insoluble tetravalent uranium in the ore body was gradually converted into soluble hexavalent uranium, such as UO2 2+ , a small amount of UO2 2+ With Cl - UO2Cl formed by complexation + and UO2 2+ (UO2)2OH produced by hydrolysis 3+ 、(UO2)2(OH)2 2+ 、(UO2)3(OH)4 2+ 、(UO2)3(OH) 5+ Positively charged particles.

[0057] The cathode and anode are conductive plastic electrodes, which are electrically connected to the negative and positive electrodes of the power supply 1, respectively. A 400-mesh nylon anode filter 7 is arranged between the anode conductive plastic electrode 3 and the sandstone uranium ore 8 to form an anode chamber 5. A 400-mesh nylon cathode filter 6 is arranged between the sandstone uranium ore 8 and the cathode conductive plastic electrode 2 to form a cathode chamber 4. Figure 2 After 24 hours of activation, a stable direct current with a voltage gradient of 0.5 V / cm was introduced and the current was applied for 24 hours. During the power-on process, the liquid flow in the ore body was accelerated and the tetravalent uranium that could not be oxidized during the activation process was oxidized, further increasing the dissolution of uranium. The uranium element first migrated directionally to the cathode conductive plastic electrode 2 in the form of positively charged particles, and then was selectively reduced on the surface of the cathode conductive plastic electrode 2. Through the charge transfer between the electrode surface and the charged particles, the hexavalent uranium element in the positively charged uranium-containing particles was electroreduced to tetravalent uranium and precipitated on the surface of the cathode conductive plastic electrode 2 in the form of UO2. After the power-on was completed, after elution and measurement, it was found that the uranium content attached to the cathode conductive plastic electrode 2 was 307.6 mg, accounting for 76.9% of the total uranium content of the experimental sandstone-type uranium ore.

[0058] Example 2

[0059] A method for extracting and separating uranium from sandstone uranium ore by applying electricity in one step is basically the same as that in Example 1, except that:

[0060] The pH of the activated leaching agent used was 2. It was finally found that the uranium content attached to the cathode conductive plastic electrode 2 was 337.2 mg, accounting for 84.3% of the total uranium content of the experimental sandstone-type uranium deposit.

[0061] Example 3

[0062] A method for extracting and separating uranium from sandstone uranium ore by applying electricity in one step is basically the same as that in Example 1, except that:

[0063] The pH of the activated leaching agent used was 1. It was finally found that the uranium content attached to the cathode conductive plastic electrode 2 was 350.0 mg, accounting for 87.5% of the total uranium content of the experimental sandstone-type uranium ore.

[0064] Example 4

[0065] A method for extracting and separating uranium from sandstone uranium ore by applying electricity in one step is basically the same as that in Example 1, except that:

[0066] The pH of the activated leaching agent used was 0.5. The uranium content attached to the cathode conductive plastic electrode 2 was found to be 356.8 mg, accounting for 89.2% of the total uranium content of the experimental sandstone-type uranium deposit.

[0067] Example 5

[0068] A method for extracting and separating uranium from sandstone uranium ore by applying electricity in one step is basically the same as that in Example 2, except that:

[0069] The volume of the activated leaching agent FeCl3+HCl was 1 L. It was finally found that the uranium content attached to the cathode conductive plastic electrode 2 was 261.6 mg, accounting for 65.4% of the total uranium content of the experimental sandstone-type uranium deposit.

[0070] Example 6

[0071] A method for extracting and separating uranium from sandstone uranium ore by applying electricity in one step is basically the same as that in Example 5, except that:

[0072] The volume of the activated leaching agent FeCl3+HCl was 3 L. It was finally found that the uranium content attached to the cathode conductive plastic electrode 2 was 289.2 mg, accounting for 72.3% of the total uranium content of the experimental sandstone-type uranium deposit.

[0073] Example 7

[0074] A method for extracting and separating uranium from sandstone uranium ore by applying electricity in one step is basically the same as that in Example 5, except that:

[0075] The volume of the activated leaching agent FeCl3+HCl was 8 L. It was finally found that the uranium content attached to the cathode conductive plastic electrode 2 was 345.2 mg, accounting for 86.3% of the total uranium content of the experimental sandstone-type uranium deposit.

[0076] Example 8

[0077] A method for extracting and separating uranium from sandstone uranium ore by applying electricity in one step is basically the same as that in Example 5, except that:

[0078] The volume of the activated leaching agent FeCl3+HCl was 10 L. It was finally found that the uranium content attached to the cathode conductive plastic electrode 2 was 360.4 mg, accounting for 90.1% of the total uranium content of the experimental sandstone-type uranium deposit.

[0079] Example 9

[0080] A method for extracting and separating uranium from sandstone uranium ore by applying electricity in one step is basically the same as that in Example 2, except that:

[0081] The FeCl3 concentration in the activated leaching agent was 15 g / L. The uranium content attached to the cathode conductive plastic electrode 2 was found to be 348.8 mg, accounting for 87.2% of the total uranium content of the experimental sandstone-type uranium deposit.

[0082] Example 10

[0083] A method for extracting and separating uranium from sandstone uranium ore in one step by applying electricity is basically the same as that in Example 9, except that:

[0084] The FeCl3 concentration in the activated leaching agent was 20 g / L. The uranium content attached to the cathode conductive plastic electrode 2 was found to be 357.2 mg, accounting for 89.3% of the total uranium content of the experimental sandstone-type uranium deposit.

[0085] Example 11

[0086] A method for extracting and separating uranium from sandstone uranium ore by applying electricity in one step is basically the same as that in Example 2, except that:

[0087] The voltage gradient applied between the cathode and cathode electrodes was 0.1 V / cm. The uranium content attached to the cathode conductive plastic electrode 2 was found to be 281.2 mg, accounting for 70.3% of the total uranium content of the experimental sandstone-type uranium deposit.

[0088] Example 12

[0089] A method for extracting and separating uranium from sandstone uranium ore in one step by applying electricity is basically the same as that in Example 11, except that:

[0090] The voltage gradient applied between the cathode and cathode electrodes was 0.2 V / cm. The uranium content attached to the cathode conductive plastic electrode 2 was found to be 298.0 mg, accounting for 74.5% of the total uranium content of the experimental sandstone-type uranium deposit.

[0091] Example 13

[0092] A method for extracting and separating uranium from sandstone uranium ore in one step by applying electricity is basically the same as that in Example 11, except that:

[0093] The voltage gradient applied between the cathode and cathode electrodes was 0.3 V / cm. The uranium content attached to the cathode conductive plastic electrode 2 was found to be 316.8 mg, accounting for 79.2% of the total uranium content of the experimental sandstone-type uranium deposit.

[0094] Example 14

[0095] A method for extracting and separating uranium from sandstone uranium ore in one step by applying electricity is basically the same as that in Example 11, except that:

[0096] The voltage gradient applied between the cathode and cathode electrodes was 0.4 V / cm. The uranium content attached to the cathode conductive plastic electrode 2 was found to be 323.6 mg, accounting for 80.9% of the total uranium content of the experimental sandstone-type uranium deposit.

[0097] Example 15

[0098] A method for extracting and separating uranium from sandstone uranium ore by applying electricity in one step is basically the same as that in Example 2, except that:

[0099] The voltage gradient applied between the cathode and cathode electrodes was 1.0 V / cm. The uranium content attached to the cathode conductive plastic electrode 2 was found to be 327.6 mg, accounting for 81.9% of the total uranium content of the experimental sandstone-type uranium deposit.

[0100] Example 16

[0101] A method for extracting and separating uranium from sandstone uranium ore by applying electricity in one step is basically the same as that of Example 15, except that:

[0102] The voltage gradient applied between the cathode and cathode electrodes was 1.5 V / cm. The uranium content attached to the cathode conductive plastic electrode 2 was found to be 314.4 mg, accounting for 78.6% of the total uranium content of the experimental sandstone-type uranium deposit.

[0103] Example 17

[0104] A method for extracting and separating uranium from sandstone uranium ore by applying electricity in one step is basically the same as that of Example 15, except that:

[0105] The voltage gradient applied between the cathode and cathode electrodes was 2.0 V / cm. The uranium content attached to the cathode conductive plastic electrode 2 was found to be 265.2 mg, accounting for 66.3% of the total uranium content of the experimental sandstone-type uranium deposit.

[0106] Table 1 shows the conditions of various embodiments of the present invention and the amount of uranium electroreduction by the cathode conductive plastic electrode.

[0107]

[0108] As can be seen from Table 1, when the solid-liquid ratio of Examples 1 to 4 was 1: 5 and the FeCl3 concentration was 10 g / L, the uranium was activated for 24 h and then energized for 24 h at a voltage gradient of 0.5 V / cm, the extraction effect of uranium under different pH conditions was that as the pH value decreased, the amount of uranium electroreduction precipitation on the cathode conductive plastic electrode 2 gradually increased, and the impurity rate decreased, and the purity of uranium obtained on the surface was improved; the solid-liquid ratio of Example 2 was different from that of Examples 5 to 8, and as the solid-liquid ratio decreased, the amount of uranium electroreduction precipitation gradually increased and the impurity rate decreased; the FeCl3 concentration of Example 2 was different from that of Examples 9 and 10, and trivalent iron ions were the oxidant of tetravalent uranium during the activation process. The FeCl3 concentration increased, the amount of uranium electroreduction precipitation gradually increased, and the impurity rate decreased; the voltage gradient of Example 2 was different from that of Examples 11 to 17, and within the voltage gradient of 0.1 to 0.5 V / cm, as the voltage gradient increased, the amount of uranium electroreduction precipitation significantly increased, and the content of other impurity elements in the precipitate on the cathode surface was less, that is, at a low voltage gradient of 0.1 to 0.5 V / cm, the present invention was used to perform a one-step electrochemical extraction of sandstone uranium ore, yielding a high-purity uranium-containing precipitate at the cathode. However, Examples 15-17 demonstrate the extraction and separation effects achieved at higher voltage gradients. With increasing voltage gradients, the amount of uranium electroreduction precipitation on the cathode surface significantly decreased, and the impurity rate also increased, likely due to changes in the system pH caused by electrolysis. Therefore, in practical applications, it is important to consider the electrolysis conditions at high voltage gradients. Vigorous cathode electrolysis significantly increases the pH of the cathode liquid and triggers the formation of large amounts of hydroxide precipitates from other metal elements. These precipitate into the cathode liquid or adhere to the cathode surface, reducing the extraction rate and purity of the uranium element. However, using a low voltage gradient can achieve both high and pure uranium extraction and separation results while also saving energy.

[0109] The present invention significantly reduces the amount of HCl used in leaching uranium ore at the same pH compared to H2SO4. The present invention activates the leaching agent using HCl + FeCl3, resulting in the formation of only positively charged uranium complexes in sandstone uranium ore. Under the action of electric current, the adsorption of uranium ions by mineral particles is weakened, further improving the leaching rate of uranium. High-valent uranium complexes undergo electrophysical effects such as electromigration and electroosmosis, migrating fixedly toward the cathode chamber and being selectively reduced on the surface of the cathode conductive plastic electrode. Furthermore, the present invention weakens electrolysis by controlling the initial pH of the reaction system and the electric field strength. Consequently, the electrically induced reduction of electrons at the cathode reduces high-valent uranium cations to low-valent, insoluble uranium, which is then fixed on the electrode surface, while other impurity metal ions are not precipitated on the cathode surface through hydroxides. Furthermore, uranium, due to its high reduction potential, undergoes reduction and fixation on the surface of the cathode conductive plastic electrode before other impurity metal ions, all of which contribute to improving the purity of the enriched uranium, thereby achieving a one-step electrical extraction and separation of uranium from sandstone uranium ore.

[0110] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for extracting and separating uranium from sandstone uranium ore by applying electricity in one step, characterized in that: The method includes: Uranium activation: Using an activation leaching agent to adjust the pH of the activation environment to ≤3, the uranium element in the sandstone uranium ore is converted into positively charged uranyl and its complex; wherein the activation leaching agent is a mixture of FeCl3 and a chlorine-containing inorganic acid; the solid-liquid ratio of the sandstone uranium ore to the activation leaching agent is 1 kg: 1-10 L, and the concentration of FeCl3 in the activation leaching agent is 10-20 g / L; Electric field drive: The activated sandstone uranium ore is introduced into a DC electric field, and a DC electric field with a voltage gradient of 0.1 to 0.5 V / cm is applied between the cathode and cathode electrodes, so that the uranium element moves toward the cathode chamber (4) under the action of the electric field, thereby being enriched in the cathode chamber (4) in a directionally controlled manner; Electrode selective reduction and fixation of uranium: the cathode and cathode electrodes are both conductive plastic electrodes, and the surface of the cathode conductive plastic electrode (2) selectively reduces the positively charged uranium element, and electrochemically reduces it to a low-cost insoluble uranium-containing substance and precipitates it on the surface of the cathode conductive plastic electrode (2), and the uranium-containing precipitate is collected on the surface of the cathode conductive plastic electrode (2).

2. The method for extracting and separating uranium from sandstone uranium ore by one-step electric current application according to claim 1, characterized in that: The solid-liquid ratio of the sandstone uranium ore to the activated leaching agent is 1 kg: 5~10 L.

3. The method for extracting and separating uranium from sandstone uranium ore by one-step electric current application according to claim 1, characterized in that: The pH of the activation leaching agent is 0.5-3.

4. The method for extracting and separating uranium from sandstone uranium ore by applying electricity in one step according to claim 3, characterized in that: The pH of the activated leaching agent is 0.5-1.

5. The method for extracting and separating uranium from sandstone uranium ore by one-step electric current application according to claim 1, characterized in that: The chlorine-containing inorganic acid is selected from any one or more of HCl, HClO and HClO4.

6. The method for extracting and separating uranium from sandstone uranium ore by one-step electric current application according to claim 1, characterized in that: The sandstone uranium ore after adding the activation leaching agent is activated at a temperature of 0-40° C. for 1-24 hours, and then a direct current with a voltage gradient of 0.1-0.5 V / cm is applied between the cathode and anode electrodes for 1-24 hours.

7. The method for extracting and separating uranium from sandstone uranium ore by one-step electric current application according to any one of claims 1 to 6, characterized in that: The sandstone uranium ore and the cathode conductive plastic electrode (2) and the anode conductive plastic electrode (3) are separated by a cathode filter (6) and an anode filter (7) to form a cathode chamber (4) and an anode chamber (5), respectively, and uranium elements enter the cathode chamber through the cathode filter (6); Or / and, the cathode filter (6) and the anode filter (7) are both nylon filters; Or / and, the mesh size of the cathode filter (6) and the anode filter (7) are both 400 meshes.

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