Self-collision dispersion process without destroying morphology of nano cerium oxide

Abstract

The invention relates to the technical field of nano cerium oxide production, in particular to a self-collision dispersion process without destroying the morphology of nano cerium oxide, which comprises the following steps: S1, material pretreatment: S1.1, impurity removal treatment: according to production requirements, obtaining a cerium carbonate / cerium silicate raw material, then crushing the cerium carbonate / cerium silicate raw material by air flow until D50 is 3-5 microns, then putting into a nitric acid solution for ultrasonic cleaning, and drying to obtain a cerium oxide / cerium silicate powder; neutralizing with ammonia water until the pH value is 6.0 + / -0.5, centrifugally separating, weighing the material, and ensuring that the purity of the cerium compound in the raw material is greater than or equal to 99.9%; according to the method, the dispersing-drying-magnetizing-calcining multi-stage joint control technology is adopted, the technological process is shortened, the efficiency is improved, the viscosity of homogeneous slurry is controlled through high-speed dispersing and synchronous stepped vacuum drying, secondary agglomeration is avoided, segmented calcining is combined with nitrogen-hydrogen mixed gas and the nucleating agent, lattice defects can be reduced, energy consumption can be reduced, and the method is suitable for large-scale production. Automatic parameter matching is achieved through magnetic field-flow velocity formulation linkage, the impact precision is improved, and the process stability is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of nano-cerium oxide production, and in particular to a self-collision dispersion process that does not destroy the morphology of nano-cerium oxide. Background Art

[0002] Nanocerium oxide is a high-purity cerium oxide material with a particle size ranging from 1 to 100 nanometers. It has unique physical and chemical properties and plays a key role in multiple high-tech fields. Nanocerium oxide has become a core material for semiconductor precision processing and biomedical innovation due to its size effect and versatility. It has significant potential in new energy and intelligent sensing fields in the future.

[0003] For example, the carbon nanomaterial composite with high dispersion stability and its preparation method with application number CN202410714906.3 and publication date 20241008 belongs to the field of dispersion technology of carbon nanomaterials. Graphene, carbon nanotubes, and conductive carbon black are firstly removed from impurities, and then separately prepared into dispersion liquids, and then mixed and ultrasonically dispersed, and then heated and stirred until they become a paste, vacuum dried, ground, and then dispersed. The unique geometric structures of graphene, carbon nanotubes, and conductive carbon black are used to disperse each other. Carbon tubes connect carbon tubes with carbon tubes, carbon tubes with graphene, and the wide gaps between graphene and graphene. Conductive carbon black is dispersed around and fills the remaining narrow gaps to form a stable three-dimensional network structure to achieve high dispersion stability of carbon nanomaterials.

[0004] For example, a nanomaterial dispersion device with application number CN202421011450.6 and authorization announcement date 20241227 connects the material tank, the first dispersion mechanism, the second dispersion mechanism, the third dispersion mechanism and the material circulation pump to each other through several material pipelines, and controls the flow direction of the material through the valves on the above-mentioned material pipelines, thereby realizing the separate dispersion process treatment of the first dispersion process, the second dispersion process and the third dispersion process, the combination process treatment of two of the above three dispersion processes, or the combination process treatment of the above three dispersion processes, and the utility model can perform automatic circulation of the above-mentioned each dispersion process and combination process.

[0005] Traditional mechanical dispersion, such as ultrasound and high-speed shearing, can easily damage the morphology of nanoparticles and cannot ensure the integrity of the morphology of nanoparticles, resulting in damage to the morphology quality of nanoparticles. In addition, conventional dispersion methods are difficult to achieve monodispersity of nanoparticles. Therefore, it is urgent to design a self-collision dispersion process that does not destroy the morphology of nanocerium oxide to solve the above problems. Summary of the Invention

[0006] The purpose of the present invention is to provide a self-collision dispersion process that does not destroy the morphology of nano-cerium oxide, so as to solve the above-mentioned shortcomings in the prior art.

[0007] In order to achieve the above object, the present invention provides the following technical solutions: A self-collision dispersion process that does not destroy the morphology of nano-cerium oxide comprises the following steps: Step S1. Material pretreatment: Step S1.1: Purification: Based on production requirements, obtain cerium carbonate / cerium silicate raw materials, then air-grind the cerium carbonate / cerium silicate raw materials to a D50 of 3-5 μm, then ultrasonically clean them in a nitric acid solution, and then neutralize them with ammonia water to a pH of 6.0 ± 0.5. After centrifugation, weigh the materials to ensure that the purity of the cerium compound in the raw materials is ≥ 99.9%, thereby obtaining the purified material. Among them, the air flow mill adopts a graded air flow mill with a crushing pressure of 0.8-1.2MPa; The ultrasonic cleaning frequency range is 35-45kHz, the duration is 30min, and the concentration of nitric acid solution is 0.4-0.6M.

[0008] Step S1.2: Modification treatment: The impurity-removed material is dispersed in deionized water at a solid content of 15-25 wt%, and 0.5-1.8 wt% ammonium sulfate and 3.0±0.2 wt% acrylic acid solution are added in sequence. The pH is then adjusted to 5.8-6.2 under magnetic stirring, and then a 2 nm Mn-Zn ferrite layer is coated in a water bath by coprecipitation to obtain a mixed solution. Among them, the magnetic stirring speed is 700-900rpm; The co-precipitation method is carried out at a temperature of 50-80°C and for a time of 1.5-3 hours; The thickness of the Mn-Zn ferrite layer is 1.8-2.2 nm, and the Fe / Mn molar ratio ranges from 2.8:1 to 3.2:1.

[0009] Step S2. Dispersion and drying: Add the mixed solution to a high-speed disperser, start the disperser for preliminary dispersion, and perform vacuum drying simultaneously to obtain a homogeneous slurry; The speed of the high-speed disperser is 11000±1000rpm, the processing time is 40-60min, and the temperature of the dispersion chamber of the high-speed disperser is maintained at 30-45℃; During vacuum drying, the pressure is reduced in a step-by-step manner: 8-10 kPa is maintained for the first 15 minutes, and then reduced to ≤5 kPa for the next 30 minutes. The temperature is maintained at 40±2°C. The solid content of the homogeneous slurry is 35-45wt%, and the viscosity is ≤50mPa·s.

[0010] Step S3. Magnetic collision treatment: The slurry is added to a syringe pump, which is started to output the slurry. The slurry is temporarily magnetized by a pulsed magnetic field generator. The magnetized slurry then enters a self-collision device for self-collision dispersion to obtain a collision product. When the syringe pump outputs the slurry, the slurry passes through the pulse magnetic field generator at a flow rate of 1.2-1.8m / s to be magnetized; The pulsed magnetic field generator has a magnetic field strength of 0.8-1.2T, a pulse width of 3-7ms, and a frequency of 0.5-2kHz; When the self-collision device is running, the angle between the two channels is 15°±1°, the impact speed is 18-22m / s, and the self-collision device is cycled for 3 times with a cooling interval of 10-15s, and the temperature is controlled at 25±1℃; The magnetic field strength is adjusted in real time according to the formula, which is as follows: ΔB=0.1T / (m·s⁻¹)×flow rate; The double flow channels of the self-collision device are made of silicon nitride ceramic with a surface roughness of Ra≤0.1μm.

[0011] Step S4. Separation and purification: After the collision is completed, the collision product is removed, washed with citric acid to remove the magnetic layer, and then filtered through a ceramic membrane and freeze-dried to obtain loose particles; Among them, during pickling, the concentration of citric acid cleaning solution is 0.08-0.12M, the liquid-to-solid ratio is 4:1 to 6:1, and the duration is 20-50 minutes; During pickling, 0.01-0.05wt% sodium polyacrylate needs to be added to the citric acid cleaning solution as a dispersing aid.

[0012] Ceramic membrane filtration uses 0.1-0.2μm pore size ceramic membrane; During freeze drying, a step-by-step temperature increase is used, as shown below: (1) 0-4 hours: -40℃ to -30℃, heating rate 2.5℃ / h; (2) 4-8 hours: -30℃ to -10℃, heating rate 5℃ / h; (3) 8-12 hours: -10℃ to 25℃, heating rate 3℃ / h; After drying, the magnetization intensity needs to be tested with a vibrating sample magnetometer, which is required to be <0.1emu / g.

[0013] Step S5. calcining in stages: placing the obtained loose particles into a calcining device, starting the calcining device for calcining, and obtaining a calcined product after calcination; Among them, the calcination is carried out in stages, and the details are as follows: The first stage: 20-150℃, heating rate 5℃ / min, keep warm for 2h to remove residual organic matter; The second stage: 150-550℃, heating rate 2℃ / min, and nitrogen-hydrogen mixed gas containing nucleating agent is introduced during calcination, and kept warm for 1h to achieve directional growth of crystal plane; The H2 content in the nitrogen-hydrogen mixture is 3-8 vol%, the amount of nucleating agent added is 0.4-0.6 vol%, and the particle size of the nucleating agent is 20-50 nm; The heating curve of the second stage calcination is nonlinear, wherein the heating rate is 1°C / min in the range of 150-400°C and 3°C / min in the range of 400-800°C.

[0014] Step S6. Finished product acquisition and testing: After calcination, the calcined product is cooled and cleaned to obtain the finished product. The finished product is then tested for morphology, particle size, and purity to confirm whether there are any problems with the product; Among them, high-resolution transmission electron microscopy was used for morphology detection, and dynamic light scattering was used for particle size distribution detection; The purity detection includes the ICP-OES method to determine the CeO2 content and the XRD method to determine the crystal phase purity.

[0015] Step S7. Waste recovery and circulation: The waste generated in the above steps 1-6 is recovered by recycling technology, wherein the metal ions in the waste liquid are treated by chelation precipitation-electrodialysis; the magnetic layer dissolved matter is recrystallized by adjusting the pH to pH = 9.0 ± 0.5 to achieve the recycling of Mn-Zn ferrite.

[0016] Among them, EDTA sodium salt is used for chelation precipitation of metal ions, with an addition amount of 0.08-0.12wt%, and a molar ratio of EDTA sodium salt to metal ions of 1.05-1.2:1; In step S7, the voltage during electrodialysis treatment is 20-40 V, the current density is 45-55 A / m², and the recovery rate is ≥95%; In step S7, the pH value of the magnetic layer recrystallization is controlled to be 8.5-9.5, and the recrystallization process adopts microwave assisted heating with a power density of 2-5 W / g and a heating rate of 10-15° C. / min.

[0017] In the above technical solution, the present invention provides a self-collision dispersion process that does not destroy the morphology of nano-cerium oxide, and the beneficial effects are: (1) The present invention adopts a multi-stage cascade control technology of dispersion-drying-magnetization-calcination to shorten the process flow and improve efficiency. The high-speed dispersion and synchronous step-by-step vacuum drying can control the viscosity of the homogeneous slurry to avoid secondary agglomeration. In addition, the segmented calcination, combined with nitrogen-hydrogen mixed gas and nucleating agent, can reduce lattice defects and reduce energy consumption. The magnetic field-flow rate formula linkage realizes automatic parameter matching, improves the impact accuracy, and significantly enhances the process stability.

[0018] (2) The present invention avoids the damage to the morphology of nano-cerium oxide caused by traditional mechanical dispersion through self-collision dispersion process and temporary magnetization treatment, ensuring that the particles maintain uniformity and integrity during the dispersion process, thereby improving the application performance of the product in fields such as semiconductors and biomedicine.

[0019] (3) The present invention integrates multiple steps such as material pretreatment, dispersion drying, magnetic collision and segmented calcination. By coordinating and controlling parameters such as temperature, magnetic field and flow rate, the operation process is simplified, energy consumption and complexity are reduced, and production efficiency and dispersion uniformity are improved.

[0020] (4) The present invention integrates multiple steps such as material pretreatment, dispersion drying, magnetic collision and segmented calcination. By coordinating the control of parameters such as temperature, magnetic field and flow rate, the operation process is simplified, energy consumption and complexity are reduced, and production efficiency and dispersion uniformity are improved. In addition, through the four core innovations of magnetic-assisted low-damage dispersion, multi-parameter intelligent joint control, waste resource recycling and surface active protection, the industry pain points such as nano-cerium oxide morphology destruction, complex process, insufficient environmental protection and performance degradation are overcome, providing a technical paradigm for high-end material manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0022] Figure 1 The present invention provides a method flow chart for a self-collision dispersion process embodiment that does not destroy the morphology of nano-cerium oxide.

[0023] Figure 2 This is a scanning electron microscope image provided for an embodiment of the present invention of a self-collision dispersion process that does not destroy the morphology of nano-cerium oxide.

[0024] Figure 3 A schematic diagram of nano-cerium oxide particles and their molecular structure provided by an embodiment of the present invention's self-collision dispersion process that does not destroy the nano-cerium oxide morphology. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0026] like Figure 1-3 As shown, an embodiment of the present invention provides a self-collision dispersion process that does not destroy the morphology of nano-cerium oxide, comprising the following steps: Step S1. Material pretreatment: Step S1.1: Purification: Based on production requirements, obtain cerium carbonate / cerium silicate raw materials, then air-grind the cerium carbonate / cerium silicate raw materials to a D50 of 3-5 μm, then ultrasonically clean them in a nitric acid solution, and then neutralize them with ammonia water to a pH of 6.0 ± 0.5. After centrifugation, weigh the materials to ensure that the purity of the cerium compound in the raw materials is ≥ 99.9%, thereby obtaining the purified material. Among them, the air flow mill adopts a graded air flow mill with a crushing pressure of 1MPa; The ultrasonic cleaning frequency range is 40 kHz, the duration is 30 min, and the concentration of nitric acid solution is 0.5 M.

[0027] Step S1.2: Modification treatment: The impurity-removed material is dispersed in deionized water at a solid content of 15-25 wt%, and 0.5-1.8 wt% ammonium sulfate and 3.0±0.2 wt% acrylic acid solution are added in sequence. The pH is then adjusted to 5.8-6.2 under magnetic stirring, and then a 2 nm Mn-Zn ferrite layer is coated in a water bath by coprecipitation to obtain a mixed solution. Among them, the magnetic stirring speed is 800 rpm; The coprecipitation method was performed at 60°C for 2 h. The thickness of the Mn-Zn ferrite layer is 2 nm, and the Fe / Mn molar ratio ranges from 2.8:1 to 3.2:1.

[0028] Step S2. Dispersion and drying: Add the mixed solution to a high-speed disperser, start the disperser for preliminary dispersion, and perform vacuum drying simultaneously to obtain a homogeneous slurry; The speed of the high-speed disperser is 11000±1000rpm, the processing time is 45min, and the temperature of the dispersion chamber of the high-speed disperser is maintained at 40°C; During vacuum drying, the pressure is reduced in a step-by-step manner: 9 kPa is maintained for the first 15 minutes, and then reduced to 5 kPa for the next 30 minutes, and the temperature is maintained at 40 ± 2 °C. The solid content of the homogeneous slurry is 35-45wt%, and the viscosity is ≤50mPa·s.

[0029] Step S3. Magnetic collision treatment: The slurry is added to a syringe pump, which is started to output the slurry. The slurry is temporarily magnetized by a pulsed magnetic field generator. The magnetized slurry then enters a self-collision device for self-collision dispersion to obtain a collision product. When the syringe pump outputs the slurry, the slurry passes through the pulse magnetic field generator at a flow rate of 1.2-1.8m / s to be magnetized; The pulsed magnetic field generator has a magnetic field strength of 0.8-1.2T, a pulse width of 3-7ms, and a frequency of 0.5-2kHz; When the self-collision device was running, the angle between the two channels was 15°±1°, the impact velocity was 18-22m / s, and the self-collision device was cycled for 3 times with a cooling interval of 10s, and the temperature was controlled at 25±1℃; The magnetic field strength is adjusted in real time according to the formula, which is as follows: ΔB=0.1T / (m·s⁻¹)×flow rate; The double flow channels of the self-collision device are made of silicon nitride ceramic with a surface roughness of Ra≤0.1μm.

[0030] It should be noted that the source of magnetism of Mn-Zn ferrite (ferrimagnetism) Superexchange: The magnetism of Mn-Zn ferrite originates from the superexchange effect mediated by oxygen ions.

[0031] Metal ions (Mn²⁺, Zn²⁺, Fe³⁺) are separated by oxygen ions, and the exchange effect is transmitted through the 2p orbital of oxygen, causing the magnetic moments of adjacent magnetic ions to be arranged in reverse (for example, the magnetic moments of Fe³⁺ at crystal positions A and B are opposite).

[0032] Since the magnetic moments at different crystal positions are not equal (for example, Fe³⁺ is dominant in the B position), the whole exhibits a net magnetic moment (ferrimagnetism).

[0033] Magnetization response characteristics: Mn-Zn ferrite is a soft magnetic material that requires an external magnetic field to become magnetized. After the magnetic field is removed, the residual magnetism is weak.

[0034] It has high magnetic permeability (suitable for high frequency) and high resistivity (avoids eddy current loss), and is suitable for rapid magnetization / demagnetization under pulsed magnetic fields.

[0035] 2. Temporary magnetization mechanism of cerium oxide When Mn-Zn ferrite is coated on cerium oxide ( ) surface, temporary magnetization is achieved by the following steps: Interface coupling: Ferrite and Ce on the surface 4 ⁺ The magnetic coupling interface is formed by oxygen bridge (-O-), so The paramagnetic electrons are affected by the magnetic moments of neighboring ferrites.

[0036] The coupling strength depends on the interfacial oxygen bond angle (the superexchange interaction is strongest at 180°).

[0037] Magnetic field induced magnetization: When applying a pulsed strong magnetic field (e.g. 1–2 T, μs level): Mn-Zn ferrite is rapidly magnetized, and its net magnetic moment is transferred to the ,make The surface electron spins are oriented and oriented, generating an induced magnetic moment.

[0038] The direction of the induced magnetic moment is consistent with the magnetic moment of ferrite, and the formula is approximately: in, is the induced magnetic moment of ceria, is the interface magnetic susceptibility, is the magnetic induction intensity of the external magnetic field, twei is the time, and τ is the relaxation time.

[0039] Demagnetization after magnetic field removal: After the pulse magnetic field ends, the Mn-Zn ferrite quickly demagnetizes due to its soft magnetic properties (remanence <5%), and the interface coupling is interrupted.

[0040] The induced magnetic moment relaxes and disappears under thermal disturbance, returning to the paramagnetic state.

[0041] Steps: Mn-Zn ferrites can achieve controllable temporary magnetization of cerium oxide through interfacial superexchange and pulsed magnetic field response, but this requires precise control of the coating structure, magnetic field parameters, and interface chemistry. This technology is suitable for magnetic repulsion buffering in self-collision dispersion.

[0042] S4. Separation and purification: After the collision is completed, the collision product is taken out, washed with citric acid to remove the magnetic layer, and then filtered through a ceramic membrane and freeze-dried to obtain a loose state. particles; Among them, during pickling, the concentration of citric acid cleaning solution is 0.1M, the liquid-to-solid ratio is 5:1, and the duration is 20-50 minutes; During pickling, 0.01-0.05wt% sodium polyacrylate needs to be added to the citric acid cleaning solution as a dispersing aid.

[0043] Ceramic membrane filtration uses 0.1-0.2μm pore size ceramic membrane; During freeze drying, a step-by-step temperature increase is used, as shown below: (1) 0-4 hours: -40℃ to -30℃, heating rate 2.5℃ / h; (2) 4-8 hours: -30℃ to -10℃, heating rate 5℃ / h; (3) 8-12 hours: -10℃ to 25℃, heating rate 3℃ / h; After drying, the magnetization intensity needs to be tested with a vibrating sample magnetometer, which is required to be <0.1emu / g.

[0044] Step S5. Segmented calcination: the obtained loose The particles are placed in a calcining device, and the calcining device is started to perform a calcination process to obtain a calcined product; Among them, the calcination is carried out in stages, and the details are as follows: The first stage: 20-150℃, heating rate 5℃ / min, keep warm for 2h to remove residual organic matter; The second stage: 150-550℃, heating rate 2℃ / min, and nitrogen-hydrogen mixed gas containing nucleating agent is introduced during calcination, and kept warm for 1h to achieve directional growth of crystal plane; The proportion of H2 in the nitrogen-hydrogen mixture is 3-8 vol%, the amount of nucleating agent added is 0.4-0.6 vol%, and the particle size of the nucleating agent is 20-50 nm; The heating curve of the second stage calcination is nonlinear, with a heating rate of 1°C / min in the range of 150-400°C and a heating rate of 3°C / min in the range of 400-800°C.

[0045] Step S6. Finished product acquisition and testing: After calcination, the calcined product is cooled and cleaned to obtain the finished product. The finished product is then tested for morphology, particle size, and purity to confirm whether there are any problems with the product; Among them, high-resolution transmission electron microscopy was used for morphology detection, and dynamic light scattering was used for particle size distribution detection; Purity testing includes ICP-OES method to determine CeO2 content and XRD method to determine crystal phase purity.

[0046] Step S7. Waste recovery and circulation: The waste generated in the above steps 1-6 is recovered by recycling technology, wherein the metal ions in the waste liquid are treated by chelation precipitation-electrodialysis; the magnetic layer dissolved matter is recrystallized by adjusting the pH to pH = 9.0 ± 0.5 to achieve the recycling of Mn-Zn ferrite.

[0047] Among them, EDTA sodium salt is used for chelation precipitation of metal ions, with an addition amount of 0.1wt%, and a molar ratio of EDTA sodium salt to metal ions of 1.05-1.2:1; In step S7, the voltage of the electrodialysis treatment is 30 V, the current density is 50 A / m², and the recovery rate is ≥95%; In step S7, the pH value of the magnetic layer recrystallization is controlled to be 8.5-9.5, and the recrystallization process adopts microwave assisted heating with a power density of 2-5 W / g and a heating rate of 10-15°C / min.

[0048] Example 1 (the present invention) Step S1.1: impurity removal Cerium carbonate was crushed to D50 = 4 μm using a graded jet mill (pressure 1.0 MPa), ultrasonically cleaned (40 kHz, 0.5 M nitric acid, 30 min), neutralized with ammonia water to pH = 6.0, and centrifuged to a cerium purity of 99.92%.

[0049] Step S1.2 Modification treatment The impurity-removing materials were dispersed in deionized water at 20 wt%, and 1.2 wt % ammonium sulfate and 3.0 wt % acrylic acid were added. The pH was adjusted to 6.0 by magnetic stirring (800 rpm), and 2 nm Mn-Zn ferrite (Fe / Mn=3:1) was co-precipitated and coated in a 50 °C water bath.

[0050] Step S2: Dispersion and drying The mixture was treated in a high-speed disperser (11000 rpm, 40°C) for 50 min, and then dried in a stepwise vacuum (9 kPa for the first 15 min to 4 kPa for the last 30 min) to obtain a homogeneous slurry with a solid content of 40 wt% and a viscosity of 45 mPa·s.

[0051] Step S3: magnetic collision The slurry passed through a pulsed magnetic field (1.0 T, pulse width 5 ms, 1 kHz) at a speed of 1.5 m / s, and circulated three times through a self-collision device (15° angle, 20 m / s impact velocity, silicon nitride flow channel Ra = 0.08 μm), followed by cooling at intervals of 12 s (25°C). The magnetic field intensity was dynamically adjusted according to ΔB = 0.1 T / (m·s⁻¹) × flow rate.

[0052] Step S4 separation and purification The product was washed with citric acid (0.1 M, liquid-to-solid ratio 5:1, 0.03 wt% sodium polyacrylate, 40 min), filtered through a 0.15 μm ceramic membrane, and freeze-dried (step-by-step heating for 12 h). The magnetization intensity was 0.05 emu / g.

[0053] Step S5: staged calcination The first stage was (20-150°C, 5°C / min, and heat preservation for 2 hours). The second stage was the introduction of 5 vol% H2 + 0.5 vol% nucleating agent (30 nm), nonlinear temperature increase (150-400°C 1°C / min - 400-550°C 3°C / min), and heat preservation for 1 hour.

[0054] Step S6: Detection HR-TEM showed that the particle sphericity was >95%, the DLS average particle size was 45 nm (PDI=0.12), and the XRD crystal phase purity was 99.95%.

[0055] Step S7: Waste recovery EDTA chelation precipitation (1.1:1 molar ratio) + electrodialysis (35V, 50A / m²) recovered cerium ions ≥97%; Mn-Zn ferrite microwave recrystallization (pH=9.0, 4W / g) had a recycling rate of 92%.

[0056] Example 2 (Comparative Example: Traditional Mechanical Dispersion + Ordinary Calcination) Raw material processing: Cerium carbonate was ball-milled to a D50 of 10 μm, washed with nitric acid (0.6 M, without ultrasound), and centrifuged to a purity of 99.5%.

[0057] Dispersion: High-speed shearing (15,000 rpm, 60°C) for 1 h, vacuum drying (constant pressure 5 kPa) to obtain a slurry with a solid content of 35 wt% (viscosity 80 mPa·s).

[0058] Calcination: Direct calcination at 550°C (5°C / min, no segmentation), no nucleating agent, the product grain size is uneven (80-200nm).

[0059] Detection: HR-TEM showed 20% particle agglomeration, XRD purity 99.0%; the waste liquid was only neutralized and discharged, and no metal was recovered.

[0060] Example 3 (Comparative Example: High-pressure homogeneous dispersion + microwave calcination) Raw material processing: cerium silicate was air flow crushed to D50 = 5μm, washed with nitric acid (0.4M, 30kHz ultrasound), purity 99.8%.

[0061] Dispersion: High pressure homogenization (200 MPa) 3 times, the slurry viscosity after drying is 60 mPa·s.

[0062] Calcination: Microwave calcination (600℃, 10℃ / min), no crystal surface control, the product surface is porous (specific surface area 120m² / g).

[0063] Detection: DLS particle size 80nm (PDI=0.35), XRD purity 99.3%; waste liquid electrodialysis recovery rate 85%, no magnetic layer recycled.

[0064] The comparative analysis table is as follows: The table above shows the core advantages of Example 1: (1) Morphology protection: Self-collision dispersion (momentum offset) + silicon nitride flow channel (low friction) makes the particle deformation rate less than 5%, which is better than traditional mechanical method (20% deformation) and high-pressure homogenization (15% crushing).

[0065] (2) Process integration: Dispersion-drying-magnetization joint control shortens the process by 50%, and step calcination (non-linear temperature increase) reduces lattice defects.

[0066] (3) Green and efficient: The combined use of EDTA and electrodialysis increased the metal recovery rate of waste liquid from 85% (Comparative Example 3) to 97%, and the Mn-Zn ferrite circulation rate was >90%.

[0067] (4) Performance improvement: Acrylic acid modification + directional growth of nucleating agent increased the catalytic activity of CeO2 by 50%, and the semiconductor polishing rate reached 150nm / min (comparative example 2 was only 100nm / min).

[0068] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

Claims

1. A self-collision dispersion process that does not destroy the morphology of nano-cerium oxide, characterized in that: The following steps are involved: Step S1. Material pretreatment: Step S1.1: Purification: Based on production requirements, obtain cerium carbonate / cerium silicate raw materials, then air-grind the cerium carbonate / cerium silicate raw materials to a D50 of 3-5 μm, then ultrasonically clean them in a nitric acid solution, and then neutralize them with ammonia water to a pH of 6.0 ± 0.

5. After centrifugation, weigh the materials to ensure that the purity of the cerium compound in the raw materials is ≥ 99.9%, thereby obtaining the purified material. Step S1.2: Modification treatment: The impurity-removed material is dispersed in deionized water at a solid content of 15-25 wt%, and 0.5-1.8 wt% ammonium sulfate and 3.0±0.2 wt% acrylic acid solution are added in sequence. The pH is then adjusted to 5.8-6.2 under magnetic stirring, and then a 2 nm Mn-Zn ferrite layer is coated in a water bath by coprecipitation to obtain a mixed solution. Step S2. Dispersion and drying: Add the mixed solution to a high-speed disperser, start the disperser for preliminary dispersion, and perform vacuum drying simultaneously to obtain a homogeneous slurry; Step S3. Magnetic collision treatment: The slurry is added to a syringe pump, which is started to output the slurry. The slurry is temporarily magnetized by a pulsed magnetic field generator. The magnetized slurry then enters a self-collision device for self-collision dispersion to obtain a collision product. Step S4. Separation and purification: After the collision is completed, the collision product is taken out, washed with citric acid to remove the magnetic layer, and then filtered through a ceramic membrane and freeze-dried to obtain a loose state. particles; Step S5. Segmented calcination: the obtained loose The particles are placed in a calcining device, and the calcining device is started to perform a calcination process to obtain a calcined product; Step S6. Finished product acquisition and testing: After calcination, the calcined product is cooled and cleaned to obtain the finished product. The finished product is then tested for morphology, particle size, and purity to confirm whether there are any problems with the product; Step S7. Waste recovery and circulation: The waste generated in the above steps 1-6 is recovered by recycling technology, wherein the metal ions in the waste liquid are treated by chelation precipitation-electrodialysis; the magnetic layer dissolved matter is recrystallized by adjusting the pH to pH = 9.0 ± 0.5 to achieve the recycling of Mn-Zn ferrite.

2. The self-collision dispersion process according to claim 1 that does not destroy the morphology of nano-cerium oxide, characterized in that: In step S1.1, the air flow mill is a graded air flow mill with a crushing pressure of 0.8-1.2 MPa; In step S1.1, the ultrasonic cleaning frequency range is 35-45 kHz, the duration is 30 minutes, and the concentration of the nitric acid solution is 0.4-0.6M.

3. The self-collision dispersion process according to claim 1 that does not destroy the morphology of nano-cerium oxide, characterized in that: In step S1.2, the magnetic stirring speed is 700-900 rpm; In step S1.2, the coprecipitation method is performed at a temperature of 50-80°C and a time of 1.5-3 hours; In the step S1.2, the thickness of the Mn-Zn ferrite layer is 1.8-2.2 nm, and the Fe / Mn molar ratio ranges from 2.8:1 to 3.2:

1.

4. The self-collision dispersion process according to claim 1 that does not destroy the morphology of nano-cerium oxide, characterized in that: In step S2, the speed of the high-speed disperser is 11000±1000 rpm, the processing time is 40-60 min, and the temperature of the dispersion chamber of the high-speed disperser is maintained at 30-45°C; In step S2, the vacuum drying stage adopts a step-by-step pressure reduction: the pressure is maintained at 8-10 kPa for the first 15 minutes, and then reduced to ≤5 kPa for the next 30 minutes, and the temperature is maintained at 40±2°C; In step S2, the solid content of the homogenized slurry is 35-45 wt % and the viscosity is ≤50 mPa·s.

5. The self-collision dispersion process according to claim 1 that does not destroy the morphology of nano-cerium oxide, characterized in that: In step S3, when the syringe pump outputs the slurry, the slurry is magnetized by passing through a pulsed magnetic field generator at a flow rate of 1.2-1.8 m / s; In step S3, the pulsed magnetic field generator has a magnetic field strength of 0.8-1.2 T, a pulse width of 3-7 ms, and a frequency of 0.5-2 kHz; In step S3, the self-collision device is operated with a double flow channel angle of 15°±1° and an impact velocity of 18-22 m / s. The self-collision device is cycled three times with a cooling interval of 10-15 seconds, and the temperature is controlled at 25±1°C. In step S3, the magnetic field strength is adjusted in real time according to the formula, which is specifically as follows: ΔB=0.1T / (m·s⁻¹)×flow rate; In step S3, the dual flow channels of the self-collision device are made of silicon nitride ceramic material with a surface roughness Ra≤0.1 μm.

6. The self-collision dispersion process according to claim 1 that does not destroy the morphology of nano-cerium oxide, characterized in that: In step S4, the concentration of the citric acid cleaning solution during pickling is 0.08-0.12M, the liquid-to-solid ratio is 4:1 to 6:1, and the pickling time is 20-50 minutes; In step S4, 0.01-0.05 wt % of sodium polyacrylate is further added to the citric acid cleaning solution during pickling as a dispersing aid.

7. The self-collision dispersion process according to claim 1 that does not destroy the morphology of nano-cerium oxide, characterized in that: In step S4, the ceramic membrane filtration is selected to have a pore size of 0.1-0.2 μm. Ceramic membrane; In step S4, during freeze drying, a stepwise temperature increase is adopted, as shown below: (1) 0-4 hours: -40℃ to -30℃, heating rate 2.5℃ / h; (2) 4-8 hours: -30℃ to -10℃, heating rate 5℃ / h; (3) 8-12 hours: -10℃ to 25℃, heating rate 3℃ / h; In step S4, after drying, the magnetization intensity needs to be detected using a vibrating sample magnetometer, which is required to be less than 0.1emu / g.

8. The self-collision dispersion process according to claim 1 that does not destroy the morphology of nano-cerium oxide, characterized in that: In step S5, the calcination is carried out in stages, and the specific steps are as follows: (1) The first stage: 20-150℃, heating rate 5℃ / min, keeping warm for 2h to remove residual organic matter; (2) The second stage: 150-550℃, heating rate 2℃ / min, and during calcination, The nitrogen and hydrogen mixture of the nucleating agent is kept warm for 1 hour to achieve directional growth of the crystal surface; The H2 content in the nitrogen-hydrogen mixed gas is 3-8 vol%. The amount of nucleating agent added is 0.4-0.6vol%. The particle size of the nucleating agent is 20-50 nm; The heating curve of the second stage calcination is nonlinear, wherein the heating rate is 1°C / min in the range of 150-400°C and 3°C / min in the range of 400-800°C.

9. The self-collision dispersion process according to claim 1 that does not destroy the morphology of nano-cerium oxide, characterized in that: In step S6, the morphology is detected by high-resolution transmission electron microscopy, and the particle size distribution is detected by dynamic light scattering; In step S6, the purity detection includes determining the CeO2 content by ICP-OES and determining the crystal phase purity by XRD.

10. The self-collision dispersion process without destroying the morphology of nano-cerium oxide according to claim 1, characterized in that: In step S7, EDTA sodium salt is used for chelating and precipitating the metal ions, with an addition amount of 0.08-0.12 wt %, and a molar ratio of EDTA sodium salt to metal ions of 1.05-1.2:1; In step S7, the voltage during electrodialysis treatment is 20-40 V, the current density is 45-55 A / m², and the recovery rate is ≥95%; In step S7, the pH value of the magnetic layer recrystallization is controlled to be 8.5-9.5, and the recrystallization process adopts microwave assisted heating with a power density of 2-5 W / g and a heating rate of 10-15° C. / min.

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