Method for one-step electrifying extraction and separation of uranium element from sandstone uranium ore

Abstract

The invention discloses a method for one-step electrifying extraction and separation of uranium elements from sandstone uranium ores, which comprises the following steps: adjusting the pH value of an activation environment to be less than or equal to 3 by using an activation leaching agent, and converting the uranium elements in the sandstone uranium ores into uranyl with positive charges and complexes thereof; and a direct-current electric field with the voltage gradient of 0.1-2 V / cm is applied between the cathode and the anode, so that the uranium element moves towards the cathode chamber under the action of the electric field and is selectively reduced on the cathode, and the uranium element is reduced into a low-valence insoluble uranium-containing substance through electrons to be precipitated on the surface of the cathode. According to the method, uranium ions only forming positive charges and complexes of the uranium ions are activated and leached, and the uranium element directionally moves towards the cathode under the electrophysical actions of electromigration, electroosmosis and the like, so that the extraction of the uranium element in the sandstone uranium ore is realized; and meanwhile, soluble uranium is reduced and fixed on the surface of the cathode conductive plastic electrode through electrochemical actions such as reduction generated by electrons on the surface of the cathode conductive plastic electrode, so that one-step separation and purification of the uranium element are realized.

Description

Technical Field

[0001] The present invention relates to a method for purifying uranium element, and particularly to a method for extracting and separating uranium element from sandstone uranium ore by one-step electrification. Background Art

[0002] In sandstone uranium ore, there are a large number of sandstone-type uranium deposits that are difficult to exploit by in-situ leaching methods. Generally, these deposits have characteristics such as poor permeability, high carbonate and argillaceous content, low ore grade, and complex geological-hydrogeological conditions of the deposit. The occurrence state of uranium minerals in uranium ore is complex, the content of tetravalent uranium is high, the symbiotic relationship with gangue minerals is close, the content of organic matter and carbonate minerals is high, the permeability and filtration performance are poor, and the solid-liquid separation is difficult, belonging to refractory ore.

[0003] Traditional uranium ore leaching methods include acid leaching of uranium, alkali leaching of uranium, CO2+O2 leaching of uranium, and microbial leaching of uranium. In acid leaching, H2SO4 is often used as the leaching agent, but precipitation is easily generated during the leaching process to block the leaching channels; in alkali leaching, Na2CO3 is often used as the leaching agent, which selectively dissolves metals, and elements such as Ca, Mg, Fe, and Al are difficult to dissolve. The alkali leaching process is usually slow and requires a high temperature; although the recently developed CO2+O2 leaching method is beneficial to the development of low-grade uranium ore, it is only applicable to ore bodies with a certain permeability; microorganisms such as Acidithiobacillus ferrooxidans have weak environmental adaptability, and such methods for microbial leaching of uranium ore have high environmental requirements. The above leaching methods are all difficult to achieve efficient extraction of uranium element from sandstone uranium ore with low permeability, low grade, diverse uranium occurrence states, complex interfacial relationships between mineral media, and high water content.

[0004] Electrical mining is a new mining technology. The 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 relevant patents are as follows: Chinese Patent CN108411130A discloses a method for electro-assisted enhanced leaching of uranium in low-grade uranium ore. A dilute sulfuric acid solution with a concentration of 35-60 g / L is used as the leaching solution, metallic iron is used as the anode, and graphite or metallic iron is used as the cathode. Under the action of direct current, the anode iron gradually dissolves and is converted into trivalent iron ions, providing an oxidant for the leaching system to promote the conversion of insoluble tetravalent uranium to soluble hexavalent uranium, and finally collecting the uranium-containing leaching solution; Chinese Patent CN109609788A discloses a method for separating uranium in uranium ore pulp by electrodialysis. The leaching agent uses a sulfuric acid solution with a mass concentration of 48-55%. The uranium-containing ore sample is stirred and leached with the leaching agent to obtain uranium-containing ore pulp; the uranium-containing ore pulp is separated by electrodialysis to finally obtain a uranium-rich solution and tailings; Chinese Patent CN114658407A discloses an electric in-situ leaching uranium extraction device and method, where uranium ore is arranged between the injection well and the pumping well; the negative electrode is arranged in the injection well; the positive electrode is arranged in the pumping well; oxygen and hydrogen peroxide are used as oxidants, and sulfuric acid and CO2 solution are used as leaching agents; the leaching solution is injected from the injection well, passes through the uranium ore, is pumped out from the pumping well, and the leaching solution is collected and then uranium extraction is carried out.

[0005] The leaching agents selected in the above-mentioned patents CN108411130A, CN109609788A and CN117564070A, such as sulfuric acid, citric acid and oxalic acid, etc., usually need to be used in large quantities. The common problem with these leaching agents is that they cannot unify uranium elements into particles with the same electrical properties. In this case, positively charged UO2 2+ and negatively charged UO2(X)2 2- and UO2(X)3 4- (X is SO4 or CO3) and other particles with different charges exist in the leaching solution. Due to the different charged properties of these ions, their migration directions in the electric field are also different, resulting in the inability to achieve the directional and controllable collection of uranium elements. In addition, if H2SO4 is used, insoluble substances may be generated, blocking the leaching channels, and thus affecting the leaching efficiency of uranium.

[0006] In addition, their final products are all uranium-containing leaching solutions, and these uranium-containing solutions need to be further processed to remove impurities and then refined uranium. At present, the composition of uranium ore leaching solution is complex, often containing various metal ion impurities, and the separation is difficult; there are various forms of uranium-containing particles in the leaching solution, such as positively charged UO2 2+ and negatively charged UO2(X)2 2- and other particles with different charges, and different purification methods will be used, and the impurity removal process is relatively complex; the commonly used extraction method also faces problems such as strong selectivity of the extractant, high cost, easy emulsification, and regeneration and treatment.

[0007] Therefore, there is an urgent need for a more efficient and convenient method for one-step extraction and separation of uranium elements.

[0008] It should be noted that the information disclosed in the above background art section is only used to strengthen the understanding of the background of the present disclosure, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0009] The object of the present invention is to provide a method for extracting and separating uranium elements from sandstone uranium ore by one-step electrification, so as to solve the problem that the existing electromotive leaching uranium extraction technology cannot achieve the enrichment of uranium elements with particles of the same charge property on a fixed electrode and simultaneously carry out separation and purification in one step. The method of the present invention can convert uranium elements in sandstone uranium ore into only positively charged ions and complexes, so as to realize the directional migration and enrichment of uranium elements by electrophysical effects such as electromigration and electroosmosis, and can efficiently and selectively reduce the oxidized high-valent uranium cations, and finally reduce and fix them on the surface of the cathode conductive plastic electrode, realizing the one-step electrification extraction, separation and purification of uranium elements.

[0010] To achieve the above object, the present invention provides a method for extracting and separating uranium elements from sandstone uranium ore by one-step electrification, and the method includes: Activation of uranium element: Using an activation leaching agent, adjusting the pH of the activation environment ≤ 3, and converting the uranium elements in the sandstone uranium ore into uranyl and its complexes with positive charges; wherein, the activation leaching agent is a mixed solution of FeCl3 and a chlorine-containing inorganic acid; Electric field driving: Introducing the activated sandstone uranium ore into a direct current electric field, applying a direct current electric field with a voltage gradient of 0.1 - 2 V / cm between the anode and cathode electrodes, and enabling the positively charged uranyl and its complexes to undergo electrophysical effects such as electromigration and electroosmosis under the action of the electric field and directionally enrich to the cathode chamber; Electrode selective reduction of uranium and fixation: Both the anode and cathode electrodes are conductive plastic electrodes. The surface of the cathode conductive plastic electrode selectively reduces the positively charged uranium elements, electrochemically reduces them to low-valent insoluble uranium-containing substances (such as UO2) and precipitates on the surface of the cathode conductive plastic electrode, while other impurity metal ions will not precipitate on the surface of the cathode conductive plastic electrode through hydroxides. The uranium-containing precipitate collected on the surface of the cathode conductive plastic electrode has a very low impurity rate.

[0011] The present invention combines the technologies of uranium element activation, electric drive and selective reduction. By converting the uranium elements in the sandstone uranium ore into only positively charged, they move towards the cathode conductive plastic electrode under the action of the electric field, and the uranium is electro-induced and reduced at the cathode conductive plastic electrode, converting the uranium into a low-valent insoluble uranium-containing substance and precipitating on the surface of the cathode conductive plastic electrode, while other impurity metal ions will not precipitate on the surface of the cathode conductive plastic electrode through hydroxides, thereby enriching uranium.

[0012] During the activation process of the present invention, some insoluble tetravalent uranium elements in the ore body are gradually converted into soluble hexavalent uranium elements, such as UO2 2+ , a small amount of UO2 2+ complexed with Cl - to form UO2Cl + and (UO2)2OH produced by the hydrolysis of UO2 2+ ​3+ , (UO2)2(OH)2 2+ , (UO2)3(OH)4 2+ , (UO2)3(OH) 5+ and other positively charged particles.

[0013] Uranium is converted into low-valent insoluble uranium-containing substances as follows: UO2 2+ (aq) + 2e - → UO2(s) UO2Cl + (aq) + 2e - → UO2(s) + Cl - (aq) Under the action of an electric field, uranyl ions are preferentially reduced. The reduction potentials of uranyl ions and their uranyl chloride complex cations are higher than those of other metal ions such as potassium, sodium, calcium, and magnesium, and are more easily reduced. If the Fe in the oxidant 3+ is not used up in the activation process, and the pH for precipitating Fe 3+ is 1.5 - 3.5, then part of the Fe 3+ will hydrolyze and precipitate into the cathode solution in the cathode solution; although the reduction potential of Fe 3+ is relatively high, the remaining unhydrolyzed Fe 3+ will be reduced to Fe 2+ prior to UO2 2+ , but the pH for precipitating Fe 2+ needs to be 7.0 - 9.0. Therefore, iron elements are not easily adsorbed and fixed on the cathode plate in the system of the method of the present invention.

[0014] In addition, other metal elements are not easily precipitated as hydroxides under acidic conditions. The pH values required for other metal elements to produce precipitates are 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.

[0015] Therefore, in the system of the present invention, only the electrochemically reduced tetravalent uranium precipitate is selectively retained on the cathode conductive plastic electrode, achieving the purpose of removing impurities and purifying uranium elements.

[0016] Preferably, the voltage gradient is 0.1~0.5 V / cm. The uranium precipitation impurity rate 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 below 5%.

[0017] Preferably, the solid-liquid ratio of the sandstone uranium ore to the activation leaching agent is 1 kg : 1~10 L.

[0018] Preferably, the solid-liquid ratio of the sandstone uranium ore to the activation leaching agent is 1 kg : 5~10 L.

[0019] Preferably, the pH of the activation leaching agent is 0.5~3.

[0020] Preferably, the pH of the activation leaching agent is 0.5~1.

[0021] Preferably, the concentration of FeCl3 in the activation leaching agent is 10~20 g / L.

[0022] 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 dosage of the leaching agent. FeCl3 can not only provide Fe 3+ to oxidize UO2 in the sandstone uranium ore, but also provide Cl - , and HCl can also provide Cl while maintaining the acidic pH environment of the sandstone uranium ore - . Compared with the leaching of uranium ore with H2SO4 (Equations 1~3), using HCl+FeCl3 as the activation leaching agent can control the uranyl ion to form a positively charged UO2Cl - complex ion only with Cl + , and will not further coordinate with more chloride ions to form a negatively charged complex, reducing the usage amount of the leaching agent for supplying Cl - .

[0023]

[0024] Preferably, after adding the activation leaching agent, the sandstone uranium ore is activated at a temperature of 0~40 °C (to ensure that there is liquid in the pulp within this temperature range) for 1~24 h, and then a direct current with a voltage gradient of 0.1~2 V / cm is applied between the two electrodes for 1~24 h.

[0025] Preferably, the sandstone uranium ore is separated from the cathode conductive plastic electrode and the anode conductive plastic electrode by a cathode filter screen and an anode filter screen respectively to form a cathode chamber and an anode chamber, and uranium elements enter the cathode chamber through the cathode filter screen; or / and, both the cathode filter screen and the anode filter screen are nylon filter screens; or / and, the mesh numbers of both the cathode filter screen and the anode filter screen are 400 meshes.

[0026] The method for extracting and separating uranium elements from sandstone uranium ore by one-step electrification in the present invention solves the problem that the existing electromotive leaching uranium extraction technology cannot achieve the enrichment of uranium elements with particles of the same charged nature on a fixed electrode and simultaneous one-step separation and purification, and has the following advantages: (1) Realize leaching and separation and purification: By controlling the activation environment, the method of the present invention can enable the uranium elements in sandstone uranium ore to form only positively charged ions and complexes, so as to realize the directional migration and enrichment of uranium elements by electrophysical effects such as electromigration and electroosmosis, with the effect of high-efficiency and rapid enrichment, and reduce the dosage of leaching agent; under the action of an external electric field, reverse adsorption is reduced and the uranium extraction efficiency is improved; by using a conductive plastic electrode as the 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 also has the advantages of weak electrolysis, corrosion resistance and low energy consumption; by controlling the initial pH of the reaction system to be low and controlling the electric field strength to weaken electrolysis, when the cathode conductive plastic electrode undergoes electroinduced reduction by gaining electrons, the 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 precipitate on the surface of the cathode conductive plastic electrode through hydroxides. At the same time, the reduction potential of uranium is high, and it preferentially undergoes reduction and fixation on the surface of the cathode conductive plastic electrode prior to other impurity metal ions, which are all beneficial to improving the purity of the enriched uranium elements and realizing one-step electrification extraction and separation and purification of uranium elements; (2) Reduce the dosage of leaching agent: The present invention selects HCl + FeCl3 as the activation leaching agent, greatly reducing the dosage of the leaching agent. FeCl3 can not only provide Fe 3+ to oxidize UO2 in sandstone uranium ore, but also provide Cl - . While maintaining the acidic pH environment of sandstone uranium ore, HCl can also provide Cl - . The research results show that compared with leaching uranium ore with H2SO4, using HCl + FeCl3 as the activation leaching agent can control the uranyl ion to form only a positively charged UO2Cl - complex ion with Cl + , and will not further complex with more chloride ions to form a negatively charged complex, reducing the usage amount of the leaching agent for supplying Cl - ;

[0027] (3) Improve the enrichment efficiency of uranium elements: Under the action of an electric field, electrophysical effects such as electromigration and electroosmosis occur to uranyl ions and uranyl complex cations and other uranium-containing positive-valence particles under the action of the electric field, accelerating the enrichment of uranium elements to the cathode conductive plastic electrode. In addition, due to the action of the external electric field force, the adsorption of mineral particles with negatively charged surfaces on uranium-containing positive ions is weakened, thereby further improving the dissolution efficiency of uranium elements. Description of the Drawings

[0028] Figure 1 This is a flowchart of the method for extracting and separating uranium elements from sandstone uranium ore by one-step electrification in the present invention.

[0029] Figure 2 This is a schematic diagram of the method for extracting and separating uranium elements from sandstone uranium ore by one-step electrification in the present invention.

[0030] Figure 3 This is an analysis diagram of the phase equilibrium of uranium ore at different pH values in the present invention.

[0031] Label: Power supply - 1; Cathode conductive plastic electrode - 2; Anode conductive plastic electrode - 3; Cathode chamber - 4; Anode chamber - 5; Cathode filter screen - 6; Anode filter screen - 7; Sandstone uranium ore - 8. Detailed implementation manners

[0032] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] It should be noted that: for those conditions not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0034] In the present invention, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of simplicity and convenience. Accordingly, the description of the numerical range or percentage range should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range.

[0035] The features mentioned in the present invention can be combined arbitrarily, as long as there is no contradiction in the combination of these features. All possible combinations should be considered as the scope described in this specification. Each feature disclosed in the specification can be replaced by any alternative feature that can provide the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the disclosed features are only general examples of equivalent or similar features.

[0036] Currently, most of the leaching agents used for extracting uranium elements from uranium ore are sulfuric acid. However, when using sulfuric acid, there will be positively charged UO2 2+ and negatively charged UO2(SO4)2 2- 、UO2(SO4)3 4-Particles have different charged properties. Under the action of an electric field, the migration directions of uranium elements are different, and it is impossible to collect uranium elements in a directionally controllable manner. Moreover, when using H2SO4, it is easy to react to form insoluble substances, clogging the leaching channels and affecting the leaching rate of uranium. In addition, their final products are all uranium-containing leaching solutions, and these uranium-containing solutions still need further operations to remove impurities and then refine uranium. The complexity of the components of uranium ore leaching solutions causes problems such as great technical difficulty, complex processes, and high costs in the current purification of uranium elements.

[0037] Therefore, the present invention provides a method for extracting and separating uranium elements from sandstone uranium ore by one-step electrification, see Figure 1 , which combines the technologies of activating uranium elements, electro-driven, and selective reduction. By converting the uranium elements in sandstone uranium ore into only positively charged ones, they move towards the cathode conductive plastic electrode 2 under the action of an electric field, and uranium is reduced by electro-induced reduction at the cathode conductive plastic electrode 2, converting uranium into a low-valence insoluble uranium-containing substance and precipitating on the surface of the cathode conductive plastic electrode 2, while other impurity metal ions will not precipitate on the surface of the cathode conductive plastic electrode 2 through hydroxides, thus enriching and obtaining uranium.

[0038] The present invention uses FeCl3 + HCl as the leaching agent and combines it with the electro-driven technology. FeCl3 can not only provide Fe 3+ to oxidize UO2 in sandstone uranium ore, but also provide Cl - for forming a UO2Cl + complex ion that still has a positive charge with the uranyl ion. HCl can provide Cl - while ensuring the acidic pH environment of sandstone uranium ore, so that only positive-valence complexes of uranium elements are formed in sandstone uranium ore instead of having both anions and cations of uranium elements in the system. In this way, electrophysical effects such as electro-migration and electro-osmosis of uranyl ions and uranyl complex cations and other uranium-containing positive-valence particles can make uranium elements enrich in the cathode chamber faster after applying an electric field. In addition, under the action of an external electric field, positively charged species migrate towards the cathode conductive plastic electrode 2, and negatively charged species migrate towards the anode conductive plastic electrode 3. Therefore, the adsorption of negatively charged mineral particles on positively charged uranium ions is weakened, further improving the leaching rate of uranium elements. Moreover, during the electrification process, in addition to accelerating the liquid flow in the ore body, it can also oxidize tetravalent uranium that was not oxidized during the activation process, further improving the dissolution of uranium. Under low pH and the action of a suitable electric field, the uranium-containing positive-charged particles enriched in the cathode chamber are selectively reduced by the cathode conductive plastic electrode, and at the same time, other metal impurity ions will not precipitate. The uranium-containing positive-charged particles are then electro-induced to be reduced by obtaining electrons through charge transfer, and a uranium-containing precipitate with a relatively high purity can be obtained on the surface of the cathode conductive plastic electrode 2.

[0039] Through the activating leaching agent of the present invention, the existing forms of uranium elements in the system are UO2 2+ , UO2 2+Complexed 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+ and other positively charged particles.

[0040] In addition, in the research of the present invention, a phase equilibrium analysis was carried out. When the reaction system starts to produce uranyl hydroxide precipitation at pH 4.2, it will affect the leaching of uranium elements. See Figure 3 . In the technology of the present invention, although it is under acidic conditions, as the pH increases, both the uranium content and the impurity rate of cathodic electroreduction will be affected. Therefore, the pH of the acidic environment in the present invention is controlled to be ≤3.

[0041] The conductive plastic electrode used in the present invention can conduct electricity and will not be corroded, and is more suitable for use in a low-pH environment, and can purify uranium elements from sandstone-type uranium ore more economically. For example, the EKG electrode in Chinese Patent CN118724422A can be used, but it is not limited thereto, and other conductive plastic electrodes can also be used.

[0042] The following is a detailed description of a method for extracting and separating uranium elements from sandstone uranium ore by one-step electrification provided by the present invention through Examples 1 to 17.

[0043] Example 1 A method for extracting and separating uranium elements from sandstone uranium ore by one-step electrification, the method comprising: Continuously introducing an activation leaching agent of FeCl3+HCl with a volume of 5 L and a pH of 3 into 1 kg of sandstone uranium ore with a uranium concentration of 400 μg / g, wherein the concentration of FeCl3 is 10 g / L, and the pH is adjusted by HCl. During the activation process, some insoluble tetravalent uranium elements in the ore body are gradually converted into soluble hexavalent uranium elements, such as UO2 2+ , a small amount of UO2 2+ Complexed 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+ and other positively charged particles.

[0044] The cathode and anode are conductive plastic electrodes. The cathode and anode are electrically connected to the negative and positive poles of the power supply 1 respectively. An anode filter screen 7 made of nylon with 400 meshes is arranged between the anode conductive plastic electrode 3 and the sandstone uranium ore 8 to form an anode chamber 5. A cathode filter screen 6 made of nylon with 400 meshes is arranged between the sandstone uranium ore 8 and the cathode conductive plastic electrode 2 to form a cathode chamber 4. See Figure 2 After activation for 24 h, a stable direct current with a voltage gradient of 0.5 V / cm was introduced, and the power was supplied for 24 h. During the power supply process, in addition to accelerating the liquid flow in the ore body, it can also oxidize the tetravalent uranium that could not be oxidized during the activation process, further improving the dissolution of uranium. The uranium element first migrates directionally as a positively charged particle to the cathode conductive plastic electrode 2, and then is 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 is electro-reduced to tetravalent uranium and precipitates on the surface of the cathode conductive plastic electrode 2 in the form of UO2, etc. After the power supply ends, through elution and measurement, it is found that the uranium content attached to the cathode conductive plastic electrode 2 is 307.6 mg, accounting for 76.9% of the total uranium content of the experimental sandstone-type uranium ore.

[0045] Example 2 A method for extracting and separating uranium elements from sandstone uranium ore by one-step power supply is basically the same as that of Example 1, except that: The pH of the activation leaching agent used is 2. Finally, it is found that the uranium content attached to the cathode conductive plastic electrode 2 is 337.2 mg, accounting for 84.3% of the total uranium content of the experimental sandstone-type uranium ore.

[0046] Example 3 A method for extracting and separating uranium elements from sandstone uranium ore by one-step power supply is basically the same as that of Example 1, except that: The pH of the activation leaching agent used is 1. Finally, it is found that the uranium content attached to the cathode conductive plastic electrode 2 is 350.0 mg, accounting for 87.5% of the total uranium content of the experimental sandstone-type uranium ore.

[0047] Example 4 A method for extracting and separating uranium elements from sandstone uranium ore by one-step power supply is basically the same as that of Example 1, except that: The pH of the activation leaching agent used is 0.5. Finally, it is found that the uranium content attached to the cathode conductive plastic electrode 2 is 356.8 mg, accounting for 89.2% of the total uranium content of the experimental sandstone-type uranium ore.

[0048] Example 5 A method for extracting and separating uranium elements from sandstone uranium ore by one-step power supply is basically the same as that of Example 2, except that: The volume of the activation leaching agent of FeCl3 + HCl was 1 L. Finally, it was 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 ore.

[0049] Example 6 A method for extracting and separating uranium elements by one-step electrification from sandstone uranium ore is basically the same as that of Example 5, except that: The volume of the activation leaching agent of FeCl3 + HCl was 3 L. Finally, it was 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 ore.

[0050] Example 7 A method for extracting and separating uranium elements by one-step electrification from sandstone uranium ore is basically the same as that of Example 5, except that: The volume of the activation leaching agent of FeCl3 + HCl was 8 L. Finally, it was 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 ore.

[0051] Example 8 A method for extracting and separating uranium elements by one-step electrification from sandstone uranium ore is basically the same as that of Example 5, except that: The volume of the activation leaching agent of FeCl3 + HCl was 10 L. Finally, it was 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 ore.

[0052] Example 9 A method for extracting and separating uranium elements by one-step electrification from sandstone uranium ore is basically the same as that of Example 2, except that: The concentration of FeCl3 in the activation leaching agent was 15 g / L. Finally, it was found that the uranium content attached to the cathode conductive plastic electrode 2 was 348.8 mg, accounting for 87.2% of the total uranium content of the experimental sandstone-type uranium ore.

[0053] Example 10 A method for extracting and separating uranium elements by one-step electrification from sandstone uranium ore is basically the same as that of Example 9, except that: The concentration of FeCl3 in the activation leaching agent was 20 g / L. Finally, it was found that the uranium content attached to the cathode conductive plastic electrode 2 was 357.2 mg, accounting for 89.3% of the total uranium content of the experimental sandstone-type uranium ore.

[0054] Example 11 A method for extracting and separating uranium elements from sandstone uranium ore by one-step electroextraction, which is basically the same as that of Example 2, except that: The voltage gradient applied between the anode and cathode electrodes is 0.1 V / cm. Finally, it was found that the uranium content attached to the cathode conductive plastic electrode 2 was 281.2 mg, accounting for 70.3% of the total uranium content of the experimental sandstone-type uranium ore.

[0055] Example 12 A method for extracting and separating uranium elements from sandstone uranium ore by one-step electroextraction, which is basically the same as that of Example 11, except that: The voltage gradient applied between the anode and cathode electrodes is 0.2 V / cm. Finally, it was found that the uranium content attached to the cathode conductive plastic electrode 2 was 298.0 mg, accounting for 74.5% of the total uranium content of the experimental sandstone-type uranium ore.

[0056] Example 13 A method for extracting and separating uranium elements from sandstone uranium ore by one-step electroextraction, which is basically the same as that of Example 11, except that: The voltage gradient applied between the anode and cathode electrodes is 0.3 V / cm. Finally, it was found that the uranium content attached to the cathode conductive plastic electrode 2 was 316.8 mg, accounting for 79.2% of the total uranium content of the experimental sandstone-type uranium ore.

[0057] Example 14 A method for extracting and separating uranium elements from sandstone uranium ore by one-step electroextraction, which is basically the same as that of Example 11, except that: The voltage gradient applied between the anode and cathode electrodes is 0.4 V / cm. Finally, it was found that the uranium content attached to the cathode conductive plastic electrode 2 was 323.6 mg, accounting for 80.9% of the total uranium content of the experimental sandstone-type uranium ore.

[0058] Example 15 A method for extracting and separating uranium elements from sandstone uranium ore by one-step electroextraction, which is basically the same as that of Example 2, except that: The voltage gradient applied between the anode and cathode electrodes is 1.0 V / cm. Finally, it was found that the uranium content attached to the cathode conductive plastic electrode 2 was 327.6 mg, accounting for 81.9% of the total uranium content of the experimental sandstone-type uranium ore.

[0059] Example 16 A method for extracting and separating uranium elements from sandstone uranium ore by one-step electroextraction, which is basically the same as that of Example 15, except that: The voltage gradient applied between the anode and cathode electrodes is 1.5 V / cm. Finally, it was found that the uranium content attached to the cathode conductive plastic electrode 2 was 314.4 mg, accounting for 78.6% of the total uranium content of the experimental sandstone-type uranium ore.

[0060] Example 17 A method for extracting and separating uranium elements by one-step electrification from sandstone uranium ore is basically the same as that of Example 15, except that: The voltage gradient applied between the anode and cathode electrodes is 2.0 V / cm. Finally, it is found that the uranium content attached to the cathode conductive plastic electrode 2 is 265.2 mg, accounting for 66.3% of the total uranium content of the experimental sandstone-type uranium ore.

[0061] Table 1 shows the conditions of each embodiment of the present invention and the electroreduction amount of uranium by the cathode conductive plastic electrode

[0062] As can be seen from Table 1, in Examples 1 to 4, when the solid-liquid ratio is 1:5 and the FeCl3 concentration is 10 g / L, after activation for 24 h and then electrification for 24 h at a voltage gradient of 0.5 V / cm, for the extraction effect of uranium under different pH conditions, as the pH value decreases, the electroreduction precipitation amount of uranium on the cathode conductive plastic electrode 2 gradually increases, the impurity rate decreases, and the purity of the obtained uranium on the surface improves; the solid-liquid ratios of Example 2 and Examples 5 to 8 are different, and as the solid-liquid ratio decreases, the electroreduction precipitation amount of uranium gradually increases and the impurity rate decreases; the FeCl3 concentrations of Example 2 and Examples 9 and 10 are different. Trivalent iron ions are the oxidants for tetravalent uranium during the activation process. As the FeCl3 concentration increases, the electroreduction precipitation amount of uranium gradually increases and the impurity rate decreases; the voltage gradients of Example 2 and Examples 11 to 17 are different. Within the voltage gradient range of 0.1 to 0.5 V / cm, as the voltage gradient increases, the electroreduction precipitation amount of uranium increases significantly, and the content of other impurity elements in the precipitate on the cathode surface is small. That is, when using the present invention to extract sandstone uranium ore by one-step electrification at a low voltage gradient of 0.1 to 0.5 V / cm, a uranium-containing precipitate with a higher purity can be obtained on the cathode; while Examples 15 to 17 are the extraction and separation effects at a higher voltage gradient. At a higher voltage gradient, as the voltage gradient increases, the electroreduction precipitation amount of uranium on the cathode surface decreases significantly, and the impurity rate also increases. It may be that electrolysis causes a change in the pH of the system. Therefore, in practical applications, the electrolysis situation at a high voltage gradient needs to be considered. Severe electrolysis at the cathode causes a significant increase in the pH of the cathode solution and triggers the formation of a large amount of hydroxide precipitates of other metal elements. They precipitate into the cathode solution or adhere to the cathode surface, reducing the extraction rate and purity of uranium elements; however, using a low voltage gradient can not only have a high and pure uranium extraction and separation effect but also save electrical energy.

[0063] The dosage of HCl in the activation leaching agent of the present invention is greatly reduced compared with the dosage of H2SO4 for leaching uranium ore under the same pH condition. The activation leaching agent of HCl+FeCl3 in the present invention enables only the formation of positive-valence complexes of uranium elements in sandstone uranium ore. Under the action of current, the adsorption of uranium ions by mineral particles is weakened, further improving the leaching rate of uranium elements; the high-valence uranium complexes undergo electrophysical effects such as electromigration and electroosmosis, and fixedly migrate towards the cathode chamber and are selectively reduced on the surface of the cathode conductive plastic electrode. In addition, the present invention weakens electrolysis by controlling the initial pH of the reaction system to be low and controlling the electric field strength. Therefore, when the electroinduced reduction occurs at the cathode to gain electrons, the high-valence uranium cations can be reduced to low-valence insoluble uranium and fixed on the electrode surface, while other impurity metal ions will not precipitate on the cathode surface through hydroxides. At the same time, the reduction potential of uranium is high, and it preferentially undergoes reduction and fixation on the surface of the cathode conductive plastic electrode prior to other impurity metal ions, which are all beneficial to improving the purity of the enriched uranium elements, thereby realizing the one-step extraction and separation of uranium elements from sandstone uranium ore by electrification.

[0064] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and substitutions of the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. A method for extracting and separating uranium elements from sandstone uranium ore by one-step electroextraction, characterized in that, The method includes: Activation of uranium element: Using an activation leaching agent, adjusting the pH of the activation environment to ≤3, and converting the uranium element in the sandstone uranium ore into positively charged uranyl and its complexes; wherein, the activation leaching agent is a mixed solution of FeCl3 and a chlorine-containing inorganic acid; Electric field driving: Introducing the activated sandstone uranium ore into a direct current electric field, applying a direct current electric field with a voltage gradient of 0.1 - 2 V / cm between the anode and cathode electrodes, so that the uranium element moves towards the cathode chamber (4) under the action of the electric field, and thus is directionally enriched in the cathode chamber (4); Electrode selective reduction of uranium and fixation: Both the anode and cathode electrodes are conductive plastic electrodes. The positively charged uranium element is selectively reduced on the surface of the cathode conductive plastic electrode (2), electrochemically reduced to a low-valence insoluble uranium-containing substance and precipitated 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 elements by one-step electrification from sandstone uranium ore according to claim 1, characterized in that, The voltage gradient is 0.1 - 0.5 V / cm.

3. The method for extracting and separating uranium elements by one-step electroextraction from sandstone uranium ore according to claim 1, characterized in that, The solid-liquid ratio of the sandstone uranium ore to the activation leaching agent is 1 kg : 1 - 10 L.

4. The method for extracting and separating uranium elements by one-step electrification from sandstone uranium ore according to claim 3, characterized in that, The solid-liquid ratio of the sandstone uranium ore to the activation leaching agent is 1 kg : 5 - 10 L.

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

6. The method for extracting and separating uranium elements by one-step electroextraction from sandstone uranium ore according to claim 5, characterized in that The pH of the activation leaching agent is 0.5 - 1.

7. The method for extracting and separating uranium elements by one-step electrification from sandstone uranium ore according to claim 1, characterized in that The concentration of FeCl3 in the activation leaching agent is 10 - 20 g / L.

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

9. The method for extracting and separating uranium elements by one-step electroextraction from sandstone uranium ore according to claim 1, characterized in that, After adding the activation leaching agent, the sandstone uranium ore is activated at a temperature of 0 - 40°C for 1 - 24 h, 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 h.

10. The method for extracting and separating uranium elements by one-step electrification from sandstone uranium ore according to any one of claims 1 to 9, characterized in that, The sandstone uranium ore is separated from the cathode conductive plastic electrode (2) and the anode conductive plastic electrode (3) by a cathode filter screen (6) and an anode filter screen (7) respectively to form a cathode chamber (4) and an anode chamber (5), and the uranium element enters the cathode chamber through the cathode filter screen (6); Or / and, both the cathode filter screen (6) and the anode filter screen (7) are nylon filter screens; Or / and, the mesh number of both the cathode filter screen (6) and the anode filter screen (7) is 400 mesh.

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