A method and apparatus for activating argillaceous sandstone uranium deposits

Abstract

This invention discloses a method and apparatus for activating uranium ore in argillaceous sandstone, relating to the field of uranium resource development technology. It comprises BaTiO3 nanowires and carbon nitride, with the BaTiO3 nanowires and carbon nitride composite forming a piezoelectric catalytic heterostructure with interfacial coupling effects. Under mechanical stress, the BaTiO3 nanowires generate a piezoelectric polarization field, promoting the effective separation of electron-hole pairs; carbon nitride synergistically enhances the generation and migration efficiency of charge carriers with the BaTiO3 nanowires. This composite catalyst can activate hydrogen peroxide in situ using the mechanical energy provided by stirring without the need for an external power source or strong radiation, maintaining high catalytic activity even in complex slurry environments. The apparatus provided by this invention significantly improves the piezoelectric catalytic efficiency of the composite catalyst through the deep synergy of multi-stage deformation and three-dimensional turbulence, making it suitable for the green and efficient leaching of uranium ore in argillaceous sandstone with low permeability and high clay content.

Description

Technical Field

[0001] This invention relates to the field of uranium resource development technology, and more specifically, to a method and apparatus for activating argillaceous sandstone uranium ore. Background Technology

[0002] Currently, in-situ leaching and heap leaching are the main methods for mining sandstone-type uranium deposits. The effectiveness of these technologies largely depends on the permeability characteristics of the ore layer. Some of the uranium deposits currently known are low-permeability argillaceous sandstone uranium deposits. These ores contain a large amount of clay minerals (such as kaolinite and montmorillonite). These minerals not only adsorb uranyl ions from the solution, causing a "chemical blockage," but also undergo hydration and expansion during the leaching process, leading to a "physical blockage" of the ore layer's pore structure. This severely hinders the sufficient contact between the leaching agent and the uranium minerals. This dual blockage effect directly leads to a series of problems, including low efficiency of traditional acid or alkaline leaching processes, a dramatic increase in chemical reagent consumption, and high production costs.

[0003] Hydrogen peroxide, due to its strong oxidizing properties and its environmentally friendly decomposition product (water), is considered a highly promising clean oxidant. Activated H₂O₂ molecules produce reactive oxygen species such as hydroxyl radicals, which can effectively attack the crystal structure of uranium minerals and promote uranium leaching. However, traditional H₂O₂ activation methods (such as the Fenton reaction) typically require strict pH control and rely on the catalytic effect of ferrous ions, significantly limiting their applicability in complex real-world slurry systems.

[0004] Piezoelectric catalysis is an emerging technology that can convert widely available mechanical energy (such as ultrasound, fluid stirring, vibration, etc.) into chemical energy. When a piezoelectric material is subjected to mechanical stress, a piezoelectric polarization field is generated inside it, which can effectively drive the separation of electron-hole pairs. These charge carriers can migrate to the material surface and participate in redox reactions.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a method and apparatus for activating uranium ore in argillaceous sandstone.

[0007] This invention is implemented as follows:

[0008] In a first aspect, the present invention provides a method for activating uranium ore in argillaceous sandstone, comprising contacting a mixture of uranium-bearing argillaceous sandstone slurry and hydrogen peroxide solution with a composite catalyst to react, wherein the hydrogen peroxide is activated in situ to generate hydroxyl radicals to oxidize and leach uranium from the uranium-bearing argillaceous sandstone slurry;

[0009] The composite catalyst comprises BaTiO3 nanowires and carbon nitride. The BaTiO3 nanowires and carbon nitride are combined to form a piezoelectric catalytic heterostructure with interfacial coupling effect.

[0010] Secondly, the present invention provides an apparatus for activating argillaceous sandstone uranium ore, applicable to the method of any of the foregoing embodiments, comprising a container and a stirring assembly, wherein the stirring assembly is housed within the container.

[0011] The mixing assembly includes a mixing shaft and at least one mixing blade assembly mounted on the mixing shaft. Each mixing blade assembly includes at least one long mixing blade and at least one short mixing blade, and the long mixing blade and the short mixing blade are alternately arranged along the axial direction. The length of the mixing blade of the long mixing blade is greater than the length of the mixing blade of the short mixing blade.

[0012] At least one of the stirring blades, stirring shaft, and inner wall surface of the container is provided with a composite catalyst coating, which is formed by a composite catalyst.

[0013] The present invention has the following beneficial effects:

[0014] This invention provides a method and apparatus for activating uranium ore in argillaceous sandstone. When this composite catalyst is applied to leaching uranium from a slurry, BaTiO3 nanowires generate a piezoelectric polarization field under mechanical stress, promoting the effective separation of electron-hole pairs. Specifically, the barium titanate (BaTiO3) nanowires used in this invention have a higher aspect ratio and unidirectionality compared to traditional particle morphologies, making them more prone to deformation under mechanical stress and exhibiting significantly enhanced piezoelectric response characteristics. Carbon nitride not only possesses good chemical stability and specific surface area but also exhibits certain piezoelectric properties, enabling it to synergistically enhance carrier generation and migration efficiency with BaTiO3 nanowires. The carbon nitride selected in this invention, in addition to the traditional g-C3N4, also includes C3N5, C3N6, and C3N7, with higher nitrogen content. The nitrogen-rich heterocycles within the molecular structure optimize the electronic structure, effectively reducing the material band gap and significantly improving carrier separation efficiency and migration rate. The tight interfacial coupling formed between the two helps reduce interfacial resistance, increase charge transfer rate, and allow more carriers to participate in surface redox reactions. This heterostructure enables in-situ activation of hydrogen peroxide using the mechanical energy provided by stirring, without the need for external power or strong radiation. This efficiently generates reactive oxygen species such as hydroxyl radicals, significantly improving the oxidative leaching capacity of uranium in argillaceous sandstone uranium deposits. Simultaneously, carbon nitride provides effective dispersion support for the BaTiO3 nanowires, preventing agglomeration during use and enhancing the overall stability and recyclability of the catalyst. These structural features work together to maintain high catalytic activity in complex slurry environments. The special stirring device provided by this invention, through multi-stage blades and surface protrusions, simultaneously introduces macroscopic deformation and microscopic turbulence during stirring, providing continuous, multi-frequency mechanical stress to the piezoelectric catalyst and significantly improving its catalytic efficiency. This device can completely eliminate reaction dead zones, ensuring uniform mixing of uranium ore slurry, catalyst, and oxidant in argillaceous sandstone, increasing the contact time and probability between the catalyst and the slurry, and improving the diffusion efficiency of hydroxyl radicals. On the other hand, through the deep synergy of "multi-stage deformation" and "three-dimensional turbulence", the device effectively overcomes the limitations of insufficient mechanical force in conventional stirring, significantly enhancing the overall efficiency and stability of the uranium leaching process, and is suitable for green and efficient leaching of argillaceous sandstone uranium ore with low permeability and high clay content. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1A structural perspective view of the apparatus for activating uranium ore in argillaceous sandstone provided in an embodiment of the present invention;

[0017] Figure 2 for Figure 1 Enlarged view of the A-structure in the middle;

[0018] Figure 3 This is a scanning electron microscope image of the composite catalyst provided in Example 1 of the present invention.

[0019] Explanation of key component symbols: 100 - Device for activating uranium ore in argillaceous sandstone; 110 - Container; 111 - Second protrusion; 121 - Stirring shaft; 122 - Long stirring paddle; 123 - Short stirring paddle; 1241 - Connecting end; 1242 - Blade edge; 1243 - First protrusion. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0021] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0022] In a first aspect, the present invention provides a method for activating uranium ore in argillaceous sandstone, comprising contacting a mixture of uranium-bearing argillaceous sandstone slurry and hydrogen peroxide solution with a composite catalyst to generate hydroxyl radicals in situ, thereby oxidizing and leaching uranium from the uranium-bearing argillaceous sandstone slurry.

[0023] The composite catalyst comprises BaTiO3 nanowires and carbon nitride, with the BaTiO3 nanowires embedded in the interior and / or surface of the carbon nitride to form a piezoelectric catalytic heterostructure with interfacial coupling effect.

[0024] Since current methods for activating hydrogen peroxide are poorly applicable in complex slurry environments, this invention provides the aforementioned composite catalyst, in which the BaTiO3 nanowires are a piezoelectric material capable of converting mechanical energy (such as ultrasound, fluid stirring, vibration, etc.) into chemical energy.

[0025] During the uranium leaching process, the slurry is continuously stirred. Under mechanical stress, the BaTiO3 nanowires generate a piezoelectric polarization field, which promotes the effective separation of electron-hole pairs. These charge carriers can migrate to the surface of the composite catalyst and participate in the redox reaction, thereby activating hydrogen peroxide to generate hydroxyl radicals.

[0026] The carbon nitride in this composite catalyst not only has good chemical stability and specific surface area, but also has certain piezoelectric properties and visible light response capability, which can synergistically enhance the generation and migration efficiency of charge carriers with BaTiO3 nanowires.

[0027] The piezoelectric catalytic heterostructure constructed from carbon nitride and BaTiO3 nanowires exhibits a tight interfacial coupling that helps reduce interfacial resistance and increase charge transfer rate, enabling more piezoelectrically generated charge carriers to participate in surface redox reactions. Therefore, without the need for an external power source or strong radiation, the mechanical energy provided by stirring can be used to activate hydrogen peroxide in situ, efficiently generating reactive oxygen species such as hydroxyl radicals, thus significantly improving the oxidative leaching capacity of uranium in argillaceous sandstone uranium deposits.

[0028] Meanwhile, carbon nitride provides effective dispersion support for the BaTiO3 nanowires, preventing them from agglomerating during use and improving the overall stability and recyclability of the catalyst. These structural features work together to enable the composite catalyst to maintain high catalytic activity even in complex slurry environments, making it suitable for the green and efficient leaching of uranium deposits from low-permeability, high-clay-content argillaceous sandstone.

[0029] In an optional embodiment, the mass ratio of BaTiO3 nanowires to carbon nitride is 0.2~0.5:1.0~5.0. By optimizing the ratio, the interfacial coupling effect can be maximized, promoting the separation efficiency of electron-hole pairs by the piezoelectric polarization field and enhancing the ability of charge carriers to migrate to the material surface, thereby enhancing the activation efficiency of hydrogen peroxide and increasing the generation rate of hydroxyl radicals.

[0030] And / or, the carbon nitride material includes at least one of C3N4, C3N5, C3N6 and C3N7.

[0031] And / or, the aspect ratio of BaTiO3 nanowires is 100~150, and the diameter is 0.2~0.5 μm.

[0032] In an optional embodiment, the preparation method of the composite catalyst provided by the present invention includes: mixing BaTiO3 nanowires with a carbon nitride precursor solution and then heating and evaporating to obtain a BaTiO3 nanowire-carbon nitride precursor, and calcining the BaTiO3 nanowire-carbon nitride precursor.

[0033] By directly introducing BaTiO3 nanowires into a carbon nitride precursor solution, the precursor is uniformly coated on the surface of the BaTiO3 nanowires and undergoes initial adsorption and self-assembly during heating and evaporation. This facilitates the formation of a tight interfacial contact during subsequent calcination, thereby enhancing the bonding strength between the BaTiO3 nanowires and carbon nitride. This process effectively achieves a uniform distribution of BaTiO3 nanowires in carbon nitride, avoiding phase separation or agglomeration problems that may occur with traditional physical mixing methods, thus ensuring the construction of a stable piezoelectric catalytic heterostructure.

[0034] Furthermore, by calcining the BaTiO3 nanowire-carbon nitride precursor, in-situ generation and crystallization of carbon nitride can be achieved while maintaining the integrity of the BaTiO3 nanowire crystal structure and reducing the generation of defect sites. This method is not only simple in process, easy to operate and scale up, but also allows for precise control of the microstructure and component distribution of the composite catalyst, significantly improving its piezoelectric catalytic activity and cycle stability. Ultimately, it efficiently activates hydrogen peroxide in uranium-bearing argillaceous sandstone slurry systems, promotes the continuous generation of hydroxyl radicals, and enhances the oxidative leaching effect on uranium minerals.

[0035] In an optional embodiment, the calcination parameters include: calcination temperature of 250~550℃, calcination time of 2~8h, and calcination atmosphere of inert atmosphere, such as nitrogen or other gases that do not react with the raw materials.

[0036] By controlling the calcination temperature within the aforementioned range, the carbon nitride precursor can undergo gradual pyrolysis and cyclization condensation to form carbon nitride with a stable conjugated structure, thus providing a structural basis for its good interfacial coupling with BaTiO3 nanowires. Appropriate calcination time ensures the reaction proceeds fully, facilitating the formation of a uniform and continuous composite structure and improving charge transport efficiency between heterogeneous interfaces. The introduction of an inert atmosphere prevents the BaTiO3 nanowires from being oxidized or undergoing chemical composition changes at high temperatures, while simultaneously suppressing structural damage or excessive carbonization of carbon nitride during pyrolysis, thereby maintaining the number and stability of its catalytically active sites. By controlling the calcination parameters within the aforementioned range, the integrity of the BaTiO3 nanowire crystal structure can be effectively maintained while ensuring the full generation and crystallization of carbon nitride, avoiding phase decomposition or over-sintering caused by high temperatures.

[0037] Preferably, the heating and evaporation temperature is 50~80℃.

[0038] Preferably, the carbon nitride precursor in the carbon nitride precursor solution includes at least one of dicyandiamide and 5-amino-1H-tetrazole to react and generate at least one carbon nitride structure selected from C3N4, C3N5, C3N6, and C3N7.

[0039] In an optional embodiment, the preparation method of BaTiO3 nanowires includes: performing a hydrothermal reaction of nano-titanium oxide and barium hydroxide in a strong alkaline solution to obtain a barium titanate nano precursor, and then annealing the barium titanate nano precursor.

[0040] By carrying out a hydrothermal reaction in a strong alkaline solution, high concentrations of OH- - The environment promotes the dissolution and recrystallization of titanates, inducing a solid-phase transformation reaction between nano-titanium oxide and barium hydroxide to form a one-dimensional barium titanate nano-precursor, providing a structural basis for the subsequent construction of highly efficient piezoelectric catalytic materials. The hydrothermal method enables the directional growth of crystal nuclei under relatively mild conditions, effectively controlling the crystal morphology and size distribution of the products.

[0041] Then, the barium titanate nanoprecursor is annealed to remove residual impurities and promote the transformation of amorphous or low-crystallinity barium titanate into a highly crystalline perovskite structure. This significantly reduces the defect site density within the material, improving its piezoelectric properties and charge carrier migration ability. This method combines the morphology controllability of the hydrothermal method with the crystallization optimization advantages of annealing to obtain highly crystalline BaTiO3 nanowires. This provides high-quality functional components for constructing high-performance piezoelectric catalytic heterostructures, ultimately enhancing the piezoelectric catalytic activity and uranium leaching efficiency of the composite catalyst in uranium-bearing argillaceous sandstone slurry systems.

[0042] Preferably, the molar ratio of Ti to Ba in nano-titanium oxide and barium hydroxide is 1.0~3.0. Preferably, the barium hydroxide can be Ba(OH)2·8H2O, which is stable at room temperature.

[0043] Preferably, in order to ensure that the final BaTiO3 nanowires have good crystal quality and high morphological uniformity, the method further includes first mixing nano-titanium oxide, barium hydroxide and strong alkaline solution to obtain a homogeneous suspension, and then placing the homogeneous suspension in a high-pressure reactor for hydrothermal reaction.

[0044] The mixing and stirring time of nano-titanium oxide, barium hydroxide and strong alkali solution is 20~40min, and the total mass ratio of nano-titanium oxide and barium hydroxide to the volume ratio of strong alkali solution is 2~4g:80mL.

[0045] Preferably, the strong alkaline solution includes at least one of sodium hydroxide solution and potassium hydroxide, more preferably sodium hydroxide solution, with a concentration of 10-15 mol / L. Using sodium hydroxide solution as the main alkaline source offers advantages such as good chemical stability under high temperature and high pressure conditions, low cost, easy removal, and no introduction of impurity elements that could affect subsequent catalytic performance.

[0046] In addition, by controlling the concentration of sodium hydroxide solution within the above range, the reaction system has sufficient ionic strength and reactivity, ensuring the efficient conduct of the hydrothermal reaction and improving the crystal quality and morphological consistency of the product.

[0047] Preferably, the hydrothermal reaction temperature is 180~240℃. By controlling the hydrothermal reaction temperature within the above range, the system has sufficient energy to drive the directional assembly of titanate ions, realizing the growth and extension of crystal nuclei from nanoparticles to one-dimensional nanowire structures. This avoids the problem of insufficient reaction kinetics or poor crystallinity of products due to excessively low temperature, while also preventing side reactions or excessive crystal growth caused by excessively high temperature, which would affect the uniformity of morphology.

[0048] Preferably, the hydrothermal reaction time is 8 to 24 hours. The appropriate reaction time ensures that the nucleation and growth process of crystal nuclei is fully carried out, so that the barium titanate nanowires have high crystal quality and morphological stability.

[0049] In an optional embodiment, in order to ensure the material consistency of BaTiO3 nanowires, after the hydrothermal reaction is completed, the reactants are washed with a dilute acetic acid solution to remove impurities, and then dried to obtain barium titanate nano precursors.

[0050] Preferably, the annealing temperature is 500~800℃ and the holding time is 1~5h.

[0051] By controlling the annealing temperature within the aforementioned range, the crystal structure of the barium titanate nanoprecursor was gradually improved, significantly reducing the density of defect sites within the material and enhancing the integrity and stability of the crystal. Higher crystallinity helps enhance the piezoelectric properties of BaTiO3 nanowires, enabling them to generate a stronger piezoelectric polarization field under mechanical stress, thereby more effectively driving the separation of electron-hole pairs and improving their performance as a piezoelectric catalyst.

[0052] In an optional embodiment, the dispersing aid includes at least one of a solvent, a dispersant, and a film-forming agent to assist in the dispersion of the composite catalyst and the formation of the composite catalyst coating.

[0053] In an optional embodiment, in order to ensure uniform dispersion of the composite catalyst, the mixing sequence of the composite catalyst and the dispersing agent includes: first, ultrasonically dispersing the composite catalyst, solvent and dispersing agent, and then adding the film-forming agent and magnetically stirring to disperse it.

[0054] In an optional embodiment, the mass ratio of the composite catalyst to the dispersant is 1.0~3.0:0.1~0.5; the ratio of the composite catalyst to the solvent is 1.0~3.0g:10mL.

[0055] By controlling the mass ratio of the composite catalyst, solvent, and dispersant within the above range, it is possible to ensure that the composite catalyst is uniformly dispersed, thereby ensuring that the prepared composite catalyst coating has stable activation performance.

[0056] Preferably, the mass ratio of the composite catalyst to the film-forming agent is 1.0~3.0:2.0~6.0 to assist in the formation of the composite catalyst coating.

[0057] Preferably, the solvent is water.

[0058] The dispersant includes at least one of polyvinylpyrrolidone and sodium polyacrylate.

[0059] The film-forming agent includes at least one of aqueous polyurethane emulsion and aqueous acrylic emulsion.

[0060] Preferably, the ultrasonic dispersion time is 20-40 min; the magnetic stirring dispersion time is 1-3 h.

[0061] In summary, the present invention provides a method for activating uranium ore in argillaceous sandstone, comprising contacting a mixture of uranium-bearing argillaceous sandstone slurry and hydrogen peroxide solution with a composite catalyst as described in the foregoing embodiments or a composite catalyst prepared by any of the foregoing embodiments, wherein hydrogen peroxide is activated in situ to generate hydroxyl radicals, thereby oxidizing and leaching uranium from the uranium-bearing argillaceous sandstone slurry.

[0062] In the treatment of uranium-bearing argillaceous sandstone slurry, the composite catalyst generates a piezoelectric polarization field due to continuous mechanical stress, promoting the effective separation of electron-hole pairs. These charge carriers can migrate to the material surface, driving the decomposition of hydrogen peroxide and continuously generating highly active hydroxyl radicals. Hydroxyl radicals possess extremely strong oxidizing power, effectively attacking and oxidizing the insoluble uranium minerals in the argillaceous sandstone, converting them into soluble uranyl ions, thereby achieving efficient uranium leaching. This in-situ activation method allows the catalytic reaction to occur within the slurry system, avoiding the leaching efficiency decline problems caused by "chemical blockage" and "physical blockage" due to clay mineral adsorption of uranyl ions or hydration expansion in traditional leaching processes.

[0063] This method does not require a strongly acidic or alkaline environment, nor does it require the addition of chemical initiators such as ferrous ions, thus significantly reducing reagent consumption and negative environmental impact. It is suitable for complex multiphase slurry environments, operates under mild conditions, and is easy to control. Combined with subsequent equipment design, it can achieve continuous operation and has promising prospects for industrial application.

[0064] Please see Figure 1 Secondly, the present invention provides an apparatus 100 for activating argillaceous sandstone uranium ore, applicable to the method of any of the foregoing embodiments, comprising a container 110 and a stirring assembly, the stirring assembly being housed within the container 110.

[0065] The mixing assembly includes a mixing shaft 121 and at least one set of mixing blades mounted on the mixing shaft 121. In an optional embodiment, the number of mixing blade sets is 1 to 5, which can be specifically set according to the volume of uranium-bearing argillaceous sandstone slurry and the volume of container 110.

[0066] Each mixing blade assembly includes at least one long mixing blade 122 and at least one short mixing blade 123, with the long mixing blade 122 and the short mixing blade 123 alternating along the axial direction, and the length of the mixing blade of the long mixing blade 122 being greater than the length of the mixing blade of the short mixing blade 123.

[0067] By combining impellers of different lengths, a non-uniform flow field distribution is formed within container 110, enhancing the macroscopic deformation and overall circulation capacity of the fluid. The long impeller 122 generates strong shear force and mainstream circulation, driving the slurry to flow over a wide area and promoting initial mixing between uranium-bearing argillaceous sandstone slurry, hydrogen peroxide, and the composite catalyst. Meanwhile, the short impeller 123 creates disturbances in localized areas, effectively breaking up dead zones and improving mixing uniformity. The alternating arrangement of these two impellers along the axial direction generates vertically intersecting vortices in the fluid, significantly enhancing the three-dimensional turbulence effect and improving material mass transfer efficiency.

[0068] Meanwhile, the multiple agitator groups, with their multi-stage length structure, provide differentiated mechanical stress distribution for the composite catalyst fixed on their surface. This ensures effective excitation of the catalyst at different locations, facilitating the continuous generation of a piezoelectric polarization field by the piezoelectric catalytic heterostructure, thereby efficiently activating hydrogen peroxide to generate hydroxyl radicals. The device provided by this invention not only optimizes the hydrodynamic environment within the reaction system but also synergistically enhances the response intensity and spatial coverage of the piezoelectric catalytic reaction, thereby strengthening the oxidative leaching effect on uranium minerals.

[0069] Preferably, in order to achieve a better synergistic effect between "multi-stage deformation" and "three-dimensional turbulence", each agitator assembly includes a long agitator 122 and two short agitators 123, with the long agitator 122 located between the two short agitators 123.

[0070] Preferably, the length of the short impeller 123 is 0.4 to 0.8 times the length of the long impeller 122. This size ratio ensures that the long impeller 122 can dominate the macroscopic flow field circulation while giving the short impeller 123 sufficient structural strength to generate effective local disturbances, thereby achieving a coordinated unity between macroscopic mixing and microscopic turbulence.

[0071] Please see Figure 2Preferably, the thickness of each stirring blade gradually decreases in the direction away from the stirring shaft 121; that is, the end of each stirring blade near the stirring shaft 121 is the connecting end 1241, and the connecting end 1241 is thicker to ensure the stable installation of the stirring blade; the end of each stirring blade away from the stirring shaft 121 is the blade edge 1242, and the structure of the blade edge 1242 is thinner so that it has a stronger shearing effect and disturbance intensity on the surrounding fluid.

[0072] This structural characteristic facilitates the generation of a non-uniform mechanical stress field during stirring, causing the composite catalyst fixed on the surface of the stirring blades to be continuously subjected to alternating stress during dynamic deformation. This effectively excites the piezoelectric catalytic heterostructure to generate a piezoelectric polarization field, promoting the separation of electron-hole pairs and improving the efficiency of activated hydrogen peroxide to generate hydroxyl radicals.

[0073] Preferably, the thickness of each stirring blade at the end away from the stirring shaft 121 is 0.3~0.8cm to ensure the shearing capacity of the stirring blade; the thickness of each stirring blade at the end near the stirring shaft 121 is 4~10 times the thickness of the end away from the stirring shaft 121 to ensure stable installation of the stirring blade.

[0074] In an optional embodiment, at least one stirring blade is provided with a first protrusion 1243. By introducing a local protrusion structure on the surface of the stirring blade, directional disturbance is applied to the surrounding fluid during stirring, significantly enhancing shear force and turbulence intensity, especially forming high-frequency micro-vortices in the direction of blade movement, effectively breaking the fluid boundary layer and promoting full contact and mass transfer between uranium-bearing argillaceous sandstone slurry, hydrogen peroxide, and composite catalyst.

[0075] Preferably, each stirring blade is provided with a first protrusion 1243, the shape of which includes at least one of wedge, cone, sphere, and column, preferably wedge. The wedge-shaped first protrusion 1243 has a geometric feature of a gentle front surface and a steep back surface, which can more effectively cut the fluid, induce local pressure gradient changes, and generate stronger flow separation and vortex structure, thereby significantly improving the conversion efficiency of mechanical energy to chemical energy of the composite catalyst at the microscale, thus improving the activation effect of hydrogen peroxide.

[0076] In an optional embodiment, the inner wall of the container 110 is provided with a second protrusion 111. The second protrusion 111 can obstruct and divert the slurry flowing through the wall, breaking the low-speed laminar flow or dead zone that is easily formed in the wall-attached area, forming local turbulence and micro-vortices, significantly enhancing the mechanical shear effect at the microscale, and further applying high-frequency mechanical stress to the composite catalyst fixed on the surface of the stirring blades. This is beneficial for continuously stimulating the piezoelectric catalytic heterostructure to generate a piezoelectric polarization field, promoting the separation of electron-hole pairs, and thus efficiently activating hydrogen peroxide to generate hydroxyl radicals.

[0077] Preferably, the second protrusion 111 can be on the side wall and / or bottom wall of the container 110; preferably, the shape of the second protrusion 111 includes at least one of wedge, cone, sphere and column, preferably hemispherical, to improve the activation effect of the composite catalyst on hydrogen peroxide.

[0078] Through the synergistic effect of the second protrusion 111 and the first protrusion 1243 on the stirring assembly, a dual turbulence excitation structure is formed, which together constructs a deep synergistic environment of "multi-level deformation" and "three-dimensional turbulence", significantly improving the conversion efficiency of mechanical energy to chemical energy, and ultimately enhancing the oxidation leaching process of uranium minerals.

[0079] At least one of the stirring blades, stirring shaft 121, and inner wall surface of container 110 is provided with a composite catalyst coating, which is formed by a composite catalyst to facilitate the activation effect of hydrogen peroxide.

[0080] Preferably, the thickness of the composite catalyst coating is 20~100 μm.

[0081] Example 1

[0082] This embodiment provides a composite catalyst for activating uranium ore in argillaceous sandstone, and its preparation method is as follows:

[0083] S01, Preparation of BaTiO3 nanowires

[0084] 0.3 g of nano-titanium oxide particles and 2.5 g of barium hydroxide octahydrate were added to 80 mL of a 12 mol / L NaOH solution and stirred continuously for 30 min to obtain a homogeneous suspension. The homogeneous suspension was transferred to a high-pressure reactor and subjected to a hydrothermal reaction at 220 °C for 24 h.

[0085] The solid obtained from the hydrothermal reaction was washed, filtered, and dried to obtain barium titanate nanoprecursors. The barium titanate nanoprecursors were then kept at 700℃ for 4 hours to obtain BaTiO3 nanowires.

[0086] SO2, Preparation of composite catalysts

[0087] Take 0.2 g of BaTiO3 nanowires obtained in step S01 and 1.0 g of dicyandiamide and disperse them evenly in 50 mL of deionized water. Stir continuously at 70 °C to allow the liquid to evaporate completely, and obtain the BaTiO3 nanowire-C3N4 precursor.

[0088] The BaTiO3 nanowire-C3N4 precursor was calcined under a nitrogen atmosphere at a temperature of 550℃ for 4 hours to obtain a composite catalyst.

[0089] The microstructure of the composite catalyst provided in this embodiment is as follows: Figure 3 As shown, by Figure 3 As can be seen, the composite catalyst provided in this embodiment has BaTiO3 nanowires and C3N4 intercalated to form a piezoelectric catalytic heterostructure with interfacial coupling effect.

[0090] S03, Preparation of composite catalyst coating

[0091] Take 1.5g of the composite catalyst prepared in step S02 of the above preparation method and 0.25g of polyvinylpyrrolidone and disperse them in 10 mL of deionized water. After processing in an ultrasonic cell disruptor for 30 min, add 5.5g of aqueous polyurethane emulsion and stir magnetically for 2 h to obtain the composite catalyst coating.

[0092] Please refer to Figure 1 and Figure 2 This embodiment also provides an apparatus 100 for activating argillaceous sandstone uranium ore, including a container 110 and a stirring assembly, the stirring assembly being housed within the container 110.

[0093] The mixing assembly includes a mixing shaft 121 and a set of mixing blades mounted on the mixing shaft 121. In this embodiment, there is one set of mixing blades, and each set of mixing blades has one long mixing blade 122 and two short mixing blades 123, with the long mixing blade 122 located between the two short mixing blades 123.

[0094] Each impeller has three impeller blades. The end of each impeller blade closest to the impeller shaft 121 is the connecting end 1241, which has a thickness of 3.0 cm. The end of each impeller blade furthest from the impeller shaft 121 is the blade edge 1242, which has a thickness of 0.5 cm.

[0095] In this embodiment, the stirring blade of the short stirring paddle 123 is 15cm long, and the stirring blade of the long stirring paddle 122 is 25cm long.

[0096] In this embodiment, each stirring blade has a wedge-shaped first protrusion 1243 on its upper and lower surfaces, and the height of the first protrusion 1243 is 1.5cm.

[0097] In this embodiment, both the side wall and bottom wall of the container 110 are provided with a hemispherical second protrusion 111, the base diameter of the second protrusion 111 is 5 cm and the height is 2 cm.

[0098] Furthermore, the composite catalyst coating provided in this embodiment is sprayed onto the upper and lower surfaces of the stirring blades of the apparatus 100 for activating argillaceous sandstone uranium ore provided in this embodiment, so as to form a composite catalyst coating on the upper and lower surfaces of the stirring blades, the thickness of which is 20~100 μm.

[0099] This embodiment also provides a method for activating uranium ore in argillaceous sandstone, the specific steps of which are as follows:

[0100] The ore from a muddy sandstone uranium deposit in Inner Mongolia (uranium grade of 0.035%) was used as the test ore. It is characterized by fine grains and the presence of large amounts of illite, kaolinite, calcite and potassium feldspar.

[0101] 10 L of uranium-bearing argillaceous sandstone slurry (prepared from the above-mentioned experimental ore) with a concentration of 10 g / L and a pH value of 3 was added to the apparatus for activating argillaceous sandstone uranium ore provided in this embodiment. Then, 150 mL of hydrogen peroxide solution with a concentration of 0.5 mol / L was added, and the mixture was stirred and reacted for 1 h. The reactants were then separated into solid and liquid components, and the leaching residue was digested by digestion. The uranium content in the digestion solution was then detected by ICP-OES, and the uranium content in the leaching residue was found to be 0.0015%.

[0102] Example 2

[0103] This embodiment provides a composite catalyst for activating argillaceous sandstone uranium ore. The only difference from Example 1 is the S02 step, as detailed below:

[0104] Take 0.2 g of BaTiO3 nanowires obtained in step S01 and 1.0 g of 5-amino-1H-tetrazole and disperse them evenly in 50 mL of deionized water. Stir continuously at 70 °C to allow the liquid to evaporate completely, and obtain the BaTiO3 nanowire-C3N5 precursor.

[0105] The BaTiO3 nanowire-C3N5 precursor was calcined under a nitrogen atmosphere at a temperature of 400℃ for 4 hours to obtain a composite catalyst.

[0106] This embodiment also provides an apparatus for activating argillaceous sandstone uranium ore, which differs from Embodiment 1 only in that the raw material for the composite catalyst coating is the composite catalyst provided in this embodiment.

[0107] This embodiment also provides a method for activating uranium ore in argillaceous sandstone, the only difference from Embodiment 1 being that the apparatus for activating uranium ore in argillaceous sandstone is the same as the apparatus provided in this embodiment. The uranium content in the leaching residue of this embodiment is 0.0012%.

[0108] Example 3

[0109] This embodiment provides a composite catalyst for activating argillaceous sandstone uranium ore. The only difference from Embodiment 2 is the S02 step, as detailed below:

[0110] Take 0.2 g of BaTiO3 nanowires obtained in step S01 and 1.0 g of 5-amino-1H-tetrazole and disperse them evenly in 50 mL of deionized water. Stir continuously at 70 °C to allow the liquid to evaporate completely, and obtain the BaTiO3 nanowire-C3N6 precursor.

[0111] The BaTiO3 nanowire-C3N6 precursor was calcined under a nitrogen atmosphere at a temperature of 300℃ for 4 hours to obtain a composite catalyst.

[0112] This embodiment also provides an apparatus for activating argillaceous sandstone uranium ore, which differs from Embodiment 1 only in that the raw material for the composite catalyst coating is the composite catalyst provided in this embodiment.

[0113] This embodiment also provides a method for activating uranium ore in argillaceous sandstone, the only difference from Embodiment 1 being that the apparatus for activating uranium ore in argillaceous sandstone is the same as the apparatus provided in this embodiment. The uranium content in the leaching residue of this embodiment is 0.0011%.

[0114] Example 4

[0115] This embodiment provides a composite catalyst for activating argillaceous sandstone uranium ore. The only difference from Embodiment 2 is the S02 step, as detailed below:

[0116] Take 0.2 g of BaTiO3 nanowires obtained in step S01 and 1.0 g of 5-amino-1H-tetrazole and disperse them evenly in 50 mL of deionized water. Stir continuously at 70 °C to allow the liquid to evaporate completely, and obtain the BaTiO3 nanowire-C3N7 precursor.

[0117] The BaTiO3 nanowire-C3N7 precursor was calcined under a nitrogen atmosphere at a temperature of 250°C for 4 hours to obtain a composite catalyst.

[0118] This embodiment also provides an apparatus for activating argillaceous sandstone uranium ore, which differs from Embodiment 1 only in that the raw material for the composite catalyst coating is the composite catalyst provided in this embodiment.

[0119] This embodiment also provides a method for activating uranium ore in argillaceous sandstone, the only difference from Embodiment 1 being that the apparatus for activating uranium ore in argillaceous sandstone is the same as the apparatus provided in this embodiment. The uranium content in the leaching residue of this embodiment is 0.001%.

[0120] Comparative Example 1

[0121] This comparative example provides a catalyst for activating argillaceous sandstone uranium ore. The only difference from Example 1 is that there is no SO2 step, that is, the catalyst provided in this comparative example only contains BaTiO3 nanowires.

[0122] This comparative example also provides an apparatus for activating argillaceous sandstone uranium ore, which differs from Example 1 only in that the raw material for the composite catalyst coating is the catalyst provided in this comparative example.

[0123] This comparative example also provides a method for activating uranium ore in argillaceous sandstone, the only difference from Example 1 being that the apparatus for activating uranium ore in argillaceous sandstone is the apparatus provided in this comparative example. The uranium content in the leaching residue of this comparative example is 0.0075%.

[0124] Comparative Example 2

[0125] This comparative example provides a catalyst for activating uranium ore in argillaceous sandstone. The only difference from Example 1 is the absence of the SO1 step; that is, the catalyst provided in this comparative example only contains carbon nitride.

[0126] This comparative example also provides an apparatus for activating argillaceous sandstone uranium ore, which differs from Example 1 only in that the raw material for the composite catalyst coating is the catalyst provided in this comparative example.

[0127] This comparative example also provides a method for activating uranium ore in argillaceous sandstone, the only difference from Example 1 being that the apparatus for activating uranium ore in argillaceous sandstone is the apparatus provided in this comparative example. The uranium content in the leaching residue of this comparative example is 0.0025%.

[0128] Comparative Example 3

[0129] This comparative example provides a catalyst for activating uranium ore in argillaceous sandstone. The only difference from Example 1 is that the mass of dicyandiamide in step S02 is 0.1 g.

[0130] This comparative example also provides an apparatus for activating argillaceous sandstone uranium ore, which differs from Example 1 only in that the raw material for the composite catalyst coating is the catalyst provided in this comparative example.

[0131] This comparative example also provides a method for activating uranium ore in argillaceous sandstone, the only difference from Example 1 being that the apparatus for activating uranium ore in argillaceous sandstone is the apparatus provided in this comparative example. The uranium content in the leaching residue of this comparative example is 0.0064%.

[0132] Comparative Example 4

[0133] This comparative example provides a catalyst for activating uranium ore in argillaceous sandstone, which differs from Example 1 only in that the mass of BaTiO3 nanowires in step S02 is 0.05 g.

[0134] This comparative example also provides an apparatus for activating argillaceous sandstone uranium ore, which differs from Example 1 only in that the raw material for the composite catalyst coating is the catalyst provided in this comparative example.

[0135] This comparative example also provides a method for activating uranium ore in argillaceous sandstone, the only difference from Example 1 being that the apparatus for activating uranium ore in argillaceous sandstone is the apparatus provided in this comparative example. The uranium content in the leaching residue of this comparative example is 0.015%.

[0136] Comparative Example 5

[0137] This comparative example provides a catalyst for activating uranium ore in argillaceous sandstone. The difference from Example 1 is that in step S02, the calcination temperature is 600°C and the calcination time is 12 h.

[0138] This comparative example also provides an apparatus for activating argillaceous sandstone uranium ore, which differs from Example 1 only in that the raw material for the composite catalyst coating is the catalyst provided in this comparative example.

[0139] This comparative example also provides a method for activating uranium ore in argillaceous sandstone, the only difference from Example 1 being that the apparatus for activating uranium ore in argillaceous sandstone is the apparatus provided in this comparative example. The uranium content in the leaching residue of this comparative example is 0.0082%.

[0140] Comparative Example 6

[0141] This comparative example provides a catalyst for activating uranium ore in argillaceous sandstone. The only difference from Example 1 is that BaTiO3 nanoparticles with an average particle size of 100 nm are used instead of BaTiO3 nanowires in Example 1 in step S02. In other words, the preparation method of the catalyst provided in this comparative example does not include step S01.

[0142] This comparative example also provides an apparatus for activating argillaceous sandstone uranium ore, which differs from Example 1 only in that the raw material for the composite catalyst coating is the catalyst provided in this comparative example.

[0143] This comparative example also provides a method for activating uranium ore in argillaceous sandstone, the only difference from Example 1 being that the apparatus for activating uranium ore in argillaceous sandstone is the apparatus provided in this comparative example. The uranium content in the leaching residue of this comparative example is 0.0033%.

[0144] Comparative Example 7

[0145] This comparative example provides an apparatus for activating uranium ore in argillaceous sandstone. The only difference from Example 1 is that: no first protrusion is provided on the stirring blade, and no second protrusion is provided on the side wall and bottom wall of the container; and the stirring blade has no thickness difference, with a thickness of 3 cm at all points.

[0146] This comparative example also provides a method for activating uranium ore in argillaceous sandstone, the only difference from Example 1 being that the apparatus for activating uranium ore in argillaceous sandstone is the apparatus provided in this comparative example. The uranium content in the leaching residue of this comparative example is 0.0022%.

[0147] In summary, the method and apparatus for activating uranium ore in argillaceous sandstone provided by this invention constructs a BaTiO3 nanowire / carbon nitride composite piezoelectric catalyst and sprays it onto the surface of a specially designed stirring blade. During stirring, mechanical stress is used to excite the piezoelectric effect, efficiently activating H2O2 to generate hydroxyl radicals, achieving green and efficient uranium leaching, significantly reducing dependence on strong acids and bases and the risk of environmental pollution. Simultaneously, the device design, combining multi-stage deformation and three-dimensional turbulence, enhances macroscopic circulation and microscopic turbulence through non-uniformly distributed multi-stage stirring blades, a first protrusion on the stirring blade, and a second protrusion inside the container. This not only significantly improves piezoelectric catalytic efficiency but also effectively alleviates the adsorption and encapsulation of uranium by clay minerals, completely eliminating mixing dead zones and improving reaction uniformity and stability, demonstrating promising industrial application prospects.

[0148] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method of activating argillaceous sandstone uranium deposits, characterised in that, The application relates to a device for activating argillaceous sandstone uranium ore, which comprises the following steps: a mixture of uranium-containing argillaceous sandstone ore slurry and hydrogen peroxide solution is contacted with a composite catalyst to generate hydroxyl radicals in situ by activating hydrogen peroxide, so as to oxidize and leach uranium in the uranium-containing argillaceous sandstone ore slurry; The composite catalyst comprises BaTiO3 nanowires and carbon nitride, the BaTiO3 nanowires are compounded with the carbon nitride to form a piezoelectric catalytic heterostructure with an interface coupling effect; The device for activating argillaceous sandstone uranium ore comprises a container and a stirring assembly accommodated in the container; The stirring assembly comprises a stirring shaft and at least one stirring paddle group mounted on the stirring shaft, each stirring paddle group comprises at least one long stirring paddle and at least one short stirring paddle, and the long stirring paddles and the short stirring paddles are arranged in an axial direction alternately, the length of the stirring blade of the long stirring paddle is greater than the length of the stirring blade of the short stirring paddle; At least one of the stirring blade, the stirring shaft and the inner wall surface of the container is provided with a composite catalyst coating formed by the composite catalyst.

2. The method of claim 1, wherein, The mass ratio of the BaTiO3 nanowires to the carbon nitride is 0.2-0.5:1.0-5.0; And / or, the material of the carbon nitride comprises at least one of C3N4, C3N5, C3N6 and C3N7; And / or, the aspect ratio of the BaTiO3 nanowires is 100-150, and the diameter is 0.2-0.5 microns.

3. The method of claim 1, wherein, The preparation method of the composite catalyst comprises the following steps: the BaTiO3 nanowires are mixed with a carbon nitride precursor solution and then heated and evaporated to obtain a BaTiO3 nanowire-carbon nitride precursor, and the BaTiO3 nanowire-carbon nitride precursor is calcined.

4. The method of claim 3, wherein, The parameters of the calcination include that the calcination temperature is 250-550 DEG C, the calcination time is 2-8 hours, and the calcination atmosphere is an inert atmosphere; And / or, the temperature of the heating and evaporation is 50-80 DEG C; And / or, the carbon nitride precursor in the carbon nitride precursor solution comprises at least one of dicyandiamide and 5-amino-1H-tetrazole.

5. The method of claim 3, wherein, The preparation method of the BaTiO3 nanowires comprises the following steps: nano-titanium oxide and barium hydroxide are subjected to a hydrothermal reaction in a strong alkali solution to obtain a barium titanate nano precursor, and then the barium titanate nano precursor is subjected to annealing treatment; The preparation conditions of the BaTiO3 nanowires meet at least one of the following characteristics: Characteristic 1: the molar ratio of Ti to Ba in the nano-titanium oxide and the barium hydroxide is 1.0-3.0; Characteristic 2: the hydrothermal reaction temperature is 180-240 DEG C, and the reaction time is 8-24 hours; Characteristic 3: the annealing temperature is 500-800 DEG C, and the holding time is 1-5 hours; Characteristic 4: the strong alkali solution comprises at least one of a sodium hydroxide solution and a potassium hydroxide solution; the concentration of the sodium hydroxide solution is 10-15 mol / L. Feature 5: further comprising mixing the nano-titanium oxide, the barium hydroxide and the strong alkali solution to obtain a homogeneous suspension, and then placing the homogeneous suspension in a high-pressure reactor for hydrothermal reaction; the mixing and stirring time of the nano-titanium oxide, the barium hydroxide and the strong alkali solution is 20-40 min, and the mass ratio of the total mass of the nano-titanium oxide and the barium hydroxide to the volume of the strong alkali solution is 2-4 g:80 mL.

6. The method of claim 3, wherein, Further comprising mixing the composite catalyst with a dispersing aid to obtain a composite catalyst slurry; the dispersing aid comprises at least one of a solvent, a dispersant and a film-forming agent; and the preparation conditions of the composite catalyst slurry meet at least one of the following features: Feature 6: the mass ratio of the composite catalyst to the dispersant is 1.0-3.0:0.1-0.5; Feature 7: the ratio of the composite catalyst to the solvent is 1.0-3.0 g:10 mL; Feature 8: the mass ratio of the composite catalyst to the film-forming agent is 1.0-3.0:2.0-6.0; Feature 9: the dispersant comprises at least one of polyvinylpyrrolidone and polyacrylic acid sodium salt; the film-forming agent comprises at least one of water-based polyurethane emulsion and water-based acrylate emulsion; Feature 10: further comprising ultrasonic dispersion of the composite catalyst, the solvent and the dispersant, and then adding the film-forming agent and magnetically stirring and dispersing; the ultrasonic dispersion time is 20-40 min; and the magnetically stirring and dispersing time is 1-3 h.

7. The method of claim 1, wherein, The thickness of the composite catalyst coating is 20-100 μm.

8. The method of claim 1, wherein, The structure of the stirring assembly meets at least one of the following features: Feature 11: each stirring paddle group comprises one long stirring paddle and two short stirring paddles, and the long stirring paddle is located between the two short stirring paddles; Feature 12: the length of the short stirring paddle is 0.4-0.8 times the length of the long stirring paddle; Feature 13: the number of stirring paddle groups is 1-5; Feature 14: the thickness of each stirring blade gradually decreases in the direction away from the stirring shaft; Feature 15: the thickness of each stirring blade at the end away from the stirring shaft is 0.3-0.8 cm, and the thickness of each stirring blade at the end close to the stirring shaft is 4-10 times the thickness of the end away from the stirring shaft; Feature 16: at least one of the stirring blades is provided with a first protruding portion.

9. The method of claim 1, wherein, The inner wall surface of the container is provided with a second protruding portion.

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