Silicon oxide particle and preparation method thereof
By introducing alkali metals, aluminum, and boron into the silicon oxide precursor and utilizing the liquid-phase sintering mechanism, the problems of insufficient density and mechanical strength of silicon oxide particles were solved, achieving low-temperature and efficient preparation of silicon oxide particles with high density and high mechanical strength, while reducing energy consumption and equipment requirements.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-25
- Publication Date
- 2026-04-03
AI Technical Summary
Existing technologies for preparing silica particles suffer from insufficient density and mechanical strength, and high-temperature sintering leads to high energy consumption and demanding equipment requirements.
Alkali metals, aluminum, and boron are compounded as dopants in the silicon oxide precursor, and particle densification is achieved at low temperature through a liquid phase sintering mechanism. Alkali metals and boron are used as fluxes to form a low-melting-point liquid phase, and aluminum regulates the silicon-oxygen network structure to improve particle density and mechanical strength.
High-density and high-mechanical-strength silica particles can be prepared at lower temperatures, reducing process energy consumption and equipment requirements.
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Figure CN121778740A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of inorganic non-metallic materials technology, and in particular to silicon oxide particles and their preparation methods. Background Technology
[0002] Currently, one of the mainstream methods for preparing spherical silica particles in industry is spray granulation. This method uses silica precursors such as silica sol or tetraethyl orthosilicate hydrolysate as raw materials, disperses them into droplets through an atomizer, and sprays them into a high-temperature drying tower. During the droplet's descent, the solvent evaporates rapidly, and after solidification, spherical particles are formed. This method has advantages such as a short process flow, continuous production capability, high product sphericity, and controllable particle size distribution.
[0003] However, due to the rapid drying rate of droplets in the high-temperature gas flow, a dense, hard shell quickly forms on the surface. The internal vapor pressure generated by the continuous vaporization of the solvent easily leads to the formation of cavities within the particles, or a large number of pores due to uneven solid-phase shrinkage. Therefore, the resulting silica particles are often porous or hollow, exhibiting low packing density and tap density, and poor mechanical strength. To improve particle density, high-temperature sintering is usually required. However, pure silica has an extremely high softening point, resulting in sintering temperatures typically exceeding 1600℃. This not only places stringent demands on equipment but also consumes enormous amounts of energy, leading to high production costs. Summary of the Invention
[0004] Therefore, it is necessary to provide a silicon oxide particle and a method for preparing the same to address the above problems. The preparation method can produce silicon oxide particles with high density and high mechanical strength, and can reduce process energy consumption and equipment requirements.
[0005] A method for preparing silica particles includes the following steps:
[0006] A silica precursor is mixed with a water-soluble alkali metal salt, a water-soluble aluminum salt, and boric acid, and the pH is adjusted to acidic to obtain a composite precursor slurry.
[0007] The composite precursor slurry was spray-granulated to obtain precursor particles.
[0008] The precursor particles were calcined at high temperature to obtain silicon oxide particles.
[0009] In one embodiment, the water-soluble alkali metal salt is selected from water-soluble lithium salts;
[0010] And / or, the water-soluble aluminum salt is selected from at least one of aluminum nitrate, aluminum chloride, aluminum sulfate, and aluminum isopropoxide.
[0011] In one embodiment, the water-soluble lithium salt is selected from at least one of lithium carbonate, lithium nitrate, and lithium acetate.
[0012] In one embodiment, the precursor particles contain 0.05% to 2% by mass of alkali metal compound.
[0013] And / or, the mass fraction of aluminum compound in the precursor particles is 0.01% to 1%;
[0014] And / or, the precursor particles contain 0.01% to 3% by mass of boron compounds.
[0015] In one embodiment, the silicon oxide precursor is selected from silica sol, with a particle size of 30 nm to 100 nm and a solid content of 20 wt% to 40 wt%.
[0016] In one embodiment, during the step of adjusting the pH to acidity, the pH is controlled to be between 1 and 5.
[0017] In one embodiment, during the spray granulation step, the atomization pressure is 0.2 MPa to 0.4 MPa, the inlet temperature is 180°C to 250°C, and the outlet temperature is 90°C to 120°C.
[0018] In one embodiment, the heating rate in the high-temperature calcination step is 2°C / min to 10°C / min, the calcination temperature is 1050°C to 1200°C, and the holding time is 1 hour to 10 hours.
[0019] In one embodiment, the high-temperature calcination step involves first heating to 500°C to 800°C at a heating rate of 2°C / min to 10°C / min, holding at that temperature for 1 hour to 4 hours, and then heating to 1050°C to 1200°C at a heating rate of 2°C / min to 10°C / min, holding at that temperature for 1 hour to 10 hours.
[0020] A type of silica particles obtained using the preparation method described above.
[0021] In the preparation method of this application, dopants consisting of alkali metals, aluminum, and boron are compounded into the silicon oxide precursor. During high-temperature calcination, the doped alkali metals and boron act as efficient fluxes, forming a low-melting-point liquid phase at a lower temperature. Based on the liquid-phase sintering mechanism, this promotes material migration and pore filling, achieving rapid particle densification. Simultaneously, aluminum acts as a silicon-oxygen network structure modifier, effectively compensating for network weakening caused by liquid phase formation and enhancing particle structural stability. Therefore, silicon oxide particles with high density and high mechanical strength can be prepared, while reducing process energy consumption and equipment requirements. Attached Figure Description
[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0023] Figure 1 This is a scanning electron microscope image of the silicon oxide particles prepared in Example 1 of this application;
[0024] Figure 2 This is a particle size distribution diagram of the silica particles prepared in Example 1 of this application;
[0025] Figure 3 Isothermal adsorption-desorption curves of the silica particles prepared in Example 1 of this application;
[0026] Figure 4 This is an isothermal adsorption-desorption curve of the silica particles prepared in Comparative Example 1 of this application. Detailed Implementation
[0027] To facilitate understanding of this application, it will be described in more detail below. However, it should be understood that this application can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to provide a more thorough and complete understanding of the disclosure of this application.
[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular implementations or embodiments only and is not intended to be limiting of this application. The optional range of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.
[0029] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.
[0030] The method for preparing silica particles provided in this application includes the following steps:
[0031] A silica precursor is mixed with a water-soluble alkali metal salt, a water-soluble aluminum salt, and boric acid, and the pH is adjusted to acidic to obtain a composite precursor slurry.
[0032] The composite precursor slurry was spray-granulated to obtain precursor particles.
[0033] The precursor particles were calcined at high temperature to obtain silicon oxide particles.
[0034] In the preparation method of this application, doping elements composed of alkali metals, aluminum and boron are compounded in the silicon oxide precursor, so that the precursor particles obtained by spray granulation are mainly silicon dioxide and doped with compounds of alkali metals, aluminum and boron, such as alkali metal oxides, aluminum oxide and boron oxide.
[0035] Furthermore, during the high-temperature calcination process, alkali metal and boron compounds can work together as highly efficient fluxes to form a low-melting-point liquid phase inside the particles. According to the theory of liquid-phase sintering, this liquid phase can effectively wet and encapsulate the silica particles, promoting particle rearrangement under capillary force and accelerating material migration through the dissolution-precipitation mechanism in the liquid phase. This achieves rapid pore filling and significant particle densification, ultimately enabling the sintering process to be completed at a relatively low temperature. This not only effectively improves the density of silica particles but also reduces process energy consumption and equipment requirements.
[0036] Meanwhile, the aluminum compounds in the precursor particles effectively overcome the weakening of the glass network structure caused by simply adding flux. Under the charge compensation provided by alkali metal ions, aluminum ions can [AlO4] - Tetrahedral particles enter and replace some [SiO4] tetrahedra, participating in the construction of the glass network. This process not only does not destroy the network integrity, but also significantly improves the mechanical strength and chemical stability of the final glass phase due to the reinforcing effect of Al-O bonds and the repair and strengthening of the three-dimensional network structure. Therefore, the synergistic mechanism of "charge compensation-network enhancement" formed between alkali metal ions and aluminum ions, combined with the low-temperature sintering effect of the boron-alkali metal flux system, enables the obtained silica particles to achieve low-temperature, efficient densification while possessing excellent mechanical properties and structural stability.
[0037] Among alkali metals, lithium ions, with their smallest ionic radius and high charge density, can effectively compensate for the negative charge generated by aluminum ions entering the silicon-oxygen network. Simultaneously, lithium oxide can better form a eutectic liquid phase with boron oxide at lower temperatures, promoting sintering densification. Therefore, the water-soluble alkali metal salt is preferably selected from water-soluble lithium salts, specifically from at least one of lithium carbonate, lithium nitrate, and lithium acetate.
[0038] To ensure the formation of a sufficient and effective eutectic liquid phase to drive low-temperature sintering, while avoiding excessive damage to the network due to excessive content, which would prevent aluminum from compensating and lead to a decrease in strength, the mass fraction of alkali metal compounds in the precursor particles is preferably 0.05% to 2%, for example, 0.05%, 0.1%, 0.5%, 1%, 1.5%, or 2%, and more preferably 0.1% to 0.5%, thereby calculating and controlling the amount of water-soluble alkali metal salts added to the composite precursor slurry.
[0039] To synergize with alkali metals, further reduce the liquid phase formation temperature and viscosity, optimize sintering kinetics, and participate in network regulation, the mass fraction of boron compounds in the precursor particles is preferably 0.01% to 3%, for example, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, or 3%, and more preferably 0.05% to 1%, thereby calculating and controlling the amount of boric acid added to the composite precursor slurry.
[0040] Optionally, the water-soluble aluminum salt is selected from at least one of aluminum nitrate, aluminum chloride, aluminum sulfate, and aluminum isopropoxide.
[0041] To ensure sufficient network formation to compensate for and enhance the structure, while avoiding excessive content that could lead to increased sintering temperature or the formation of high-melting-point crystalline phases, the mass fraction of aluminum compound in the precursor particles is preferably 0.01% to 1%, for example, 0.01%, 0.05%, 0.1%, 0.5%, or 1%, and more preferably 0.05% to 1%, thereby calculating and controlling the amount of water-soluble aluminum salt added to the composite precursor slurry.
[0042] In this application, the silica precursor can be selected from silica sol or tetraethyl orthosilicate hydrolysate, and is more preferably silica sol. The particle size of the silica sol is controlled to be from 30 nm to 100 nm, for example, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm, and the solid content is from 20 wt% to 40 wt%, for example, 20 wt%, 25 wt%, 30 wt%, 35 wt%, or 40 wt%. This particle size range ensures that the primary silica particles have high surface energy, providing sufficient driving force for the high-temperature calcination process; this solid content range ensures the processability of the slurry and the uniformity of the precursor particle structure after drying. Thus, the two work together to provide highly active and highly homogeneous precursor conditions for high-temperature calcination assisted by the doping system, which is conducive to achieving rapid and uniform densification of particles at relatively low temperatures and obtaining silica particles with high mechanical strength.
[0043] In order to better form spherical precursor particles during spray granulation, the pH is controlled between 1 and 5 during the pH adjustment to acidity step, such as pH 1, 2, 3, 4 or 5.
[0044] In the spray granulation step, the particle size can be controlled by adjusting the atomization pressure. In this application, the atomization pressure is preferably 0.2 MPa to 0.4 MPa, such as 0.2 MPa, 0.3 MPa, or 0.4 MPa. Meanwhile, the inlet temperature is preferably 180°C to 250°C, such as 180°C, 200°C, 220°C, or 250°C, and the outlet temperature is preferably 90°C to 120°C, such as 90°C, 100°C, 110°C, or 120°C. This ensures that the solvent evaporates quickly without being too violent, thereby improving the particle density.
[0045] In the high-temperature calcination step described in this application, the heating rate is preferably 2℃ / min to 10℃ / min, for example, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min or 10℃ / min, so as to remove the decomposition products of dopant salts such as crystal water and organic matter in the particles; the calcination temperature is preferably 1050℃ to 1200℃, for example, 1050℃, 1100℃, 1150℃ or 1200℃, etc., and the holding time is preferably 1 hour to 10 hours, for example, 1 hour, 3 hours, 5 hours, 8 hours or 10 hours, etc., so as to ensure that a sufficient amount of eutectic liquid phase with good wettability can be formed to efficiently start and complete the densification process, while effectively avoiding problems such as particle deformation, abnormal grain growth, precipitation of harmful crystalline phases and volatilization of alkali metals caused by excessive temperature, and ensuring the sphericity, high mechanical strength and chemical stability of silicon oxide particles while achieving high densification.
[0046] In order to fully remove the decomposition products of dopant salts such as crystal water and organic matter in the particles, the high-temperature calcination step is carried out in stages: first, the temperature is raised to 500°C to 800°C at a heating rate of 2°C / min to 10°C / min, and held for 1 hour to 4 hours; then, the temperature is raised to 1050°C to 1200°C at a heating rate of 2°C / min to 10°C / min, and held for 1 hour to 10 hours.
[0047] It is understood that the atmosphere in the high-temperature roasting process of this application can be air, nitrogen, argon, etc.
[0048] This application also provides silica particles obtained by the preparation method described above. These silica particles can be widely used in industrial fields such as electronics, optical communication, chemical industry and materials. For example, they can be used as key fillers in epoxy molding compounds (EMC) for large-scale integrated circuits, degreasing raw materials in the preparation process of multi-component optical fiber preforms, optical components in semiconductor component packaging materials, functional fillers in high-end coatings and engineering plastics, ceramic materials for precision casting, and important raw materials for high-end equipment and special composite materials.
[0049] The technical solution of this application will be further described below through specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.
[0050] Example 1
[0051] Weigh 1000g of silica sol with a solid content of 30wt.% (average SiO2 particle size of 55nm), and add 1.6g of aluminum nitrate, 0.7g of lithium nitrate and 2.5g of boric acid in sequence while stirring. Continue mechanical stirring for 2 hours at a stirring speed of 300 rpm. After stirring evenly, adjust the pH to 3.5 with 2% nitric acid to obtain the composite precursor slurry.
[0052] Then, the above-mentioned composite precursor slurry was granulated using a centrifugal spray dryer. The atomization method adopted was a dual-fluid pneumatic atomizing nozzle, with the inlet temperature set at 220°C, the outlet temperature at 110°C, and the atomization pressure at 0.25 MPa. The precursor particles were then collected.
[0053] Finally, the precursor particles were heated to 800°C in a muffle furnace at a rate of 5°C / min and held for 2 hours. Then, the temperature was further increased to 1150°C at a rate of 5°C / min and held for 4 hours. Afterward, the mixture was allowed to cool naturally to obtain the desired product. Figure 1 The image shows spherical silicon oxide particles.
[0054] Example 2
[0055] Weigh 1000g of silica sol with a solid content of 30wt.% (average SiO2 particle size of 55nm), add 2.1g of aluminum nitrate, 0.7g of lithium nitrate and 2.5g of boric acid in sequence while stirring, and continue mechanical stirring for 2 hours at a stirring speed of 300 rpm. After stirring evenly, adjust the pH to 3 with 2% nitric acid to obtain the composite precursor slurry.
[0056] Then, the above-mentioned composite precursor slurry was granulated using a centrifugal spray dryer. The atomization method adopted was a dual-fluid pneumatic atomizing nozzle, with the inlet temperature set at 210℃, the outlet temperature at 120℃, and the atomization pressure at 0.4MPa. The precursor particles were then collected.
[0057] Finally, the precursor particles were heated to 600°C in a muffle furnace at a rate of 5°C / min and held for 4 hours. Then, the temperature was increased to 1150°C at a rate of 4°C / min and held for 4 hours. After that, the particles were allowed to cool naturally to obtain spherical silicon oxide particles.
[0058] Example 3
[0059] Weigh 1000g of silica sol with a solid content of 30wt.% (average SiO2 particle size of 45nm), add 1.6g of aluminum nitrate, 0.7g of lithium nitrate and 2.5g of boric acid in sequence while stirring, and continue mechanical stirring for 2 hours at a stirring speed of 300 rpm. After stirring evenly, adjust the pH to 4 with 2% nitric acid to obtain the composite precursor slurry.
[0060] Then, the above-mentioned composite precursor slurry was granulated using a centrifugal spray dryer. The atomization method adopted was a dual-fluid pneumatic atomizing nozzle, with the inlet temperature set at 225°C, the outlet temperature at 110°C, and the atomization pressure at 0.3 MPa. The precursor particles were then collected.
[0061] Finally, the precursor particles were heated to 700°C in a muffle furnace at a rate of 5°C / min and held for 2 hours. Then, the temperature was increased to 1050°C at a rate of 10°C / min and held for 10 hours. After natural cooling, spherical silicon oxide particles were obtained.
[0062] Example 4
[0063] Weigh 1000g of silica sol with a solid content of 40wt.% (average particle size of SiO2 is 45nm), and add 1.1g of aluminum carbonate, 0.9g of lithium carbonate and 2.7g of boric acid in sequence while stirring. Continue mechanical stirring for 2 hours at a stirring speed of 300 rpm. After stirring evenly, adjust the pH to 3.5 with 2% nitric acid to obtain the composite precursor slurry.
[0064] Then, the above-mentioned composite precursor slurry was granulated using a centrifugal spray dryer. The atomization method adopted was a dual-fluid pneumatic atomizing nozzle, with the inlet temperature set at 200℃, the outlet temperature at 115℃, and the atomization pressure at 0.25MPa. The precursor particles were then collected.
[0065] Finally, the precursor particles were heated to 600°C in a muffle furnace at a rate of 5°C / min and held for 4 hours. Then, the temperature was increased to 1200°C at a rate of 2°C / min and held for 1 hour. After that, the particles were allowed to cool naturally to obtain spherical silicon oxide particles.
[0066] Example 5
[0067] Weigh 1000g of silica sol with a solid content of 20wt.% (average particle size of SiO2 is 55nm), and add 1.6g of aluminum nitrate, 0.7g of lithium nitrate and 0.9g of boric acid in sequence while stirring. Continue mechanical stirring for 2 hours at a stirring speed of 300 rpm. After stirring evenly, adjust the pH to 2.5 with 2% nitric acid to obtain the composite precursor slurry.
[0068] Then, the above-mentioned composite precursor slurry was granulated using a centrifugal spray dryer. The atomization method adopted was a dual-fluid pneumatic atomizing nozzle, with the inlet temperature set at 195°C, the outlet temperature at 95°C, and the atomization pressure at 0.2 MPa. The precursor particles were then collected.
[0069] Finally, the precursor particles were heated to 750°C in a muffle furnace at a rate of 5°C / min and held for 3 hours. Then, the temperature was increased to 1200°C at a rate of 5°C / min and held for 4 hours. After natural cooling, spherical silicon oxide particles were obtained.
[0070] Comparative Example 1
[0071] Weigh 1000g of silica sol with a solid content of 30wt.% (average particle size of SiO2 is 55nm), and adjust the pH to 3.5 with 2% nitric acid to obtain the precursor slurry.
[0072] Then, the above-mentioned composite precursor slurry was granulated using a centrifugal spray dryer. The atomization method adopted was a dual-fluid pneumatic atomizing nozzle, with the inlet temperature set at 220°C, the outlet temperature at 110°C, and the atomization pressure at 0.25 MPa. The precursor particles were then collected.
[0073] Finally, the precursor particles were heated to 800°C in a muffle furnace at a rate of 5°C / min and held for 2 hours. Then, the temperature was increased to 1150°C at a rate of 5°C / min and held for 4 hours. After that, the particles were allowed to cool naturally to obtain spherical silicon oxide particles.
[0074] Comparative Example 2
[0075] Weigh 1000g of silica sol with a solid content of 30wt.% (average particle size of SiO2 is 55nm), add 1.6g of aluminum nitrate and 0.7g of lithium nitrate in sequence while stirring, continue mechanical stirring for 2 hours at a stirring speed of 300 rpm, and after stirring evenly, adjust the pH to 3.5 with 2% nitric acid to obtain the composite precursor slurry.
[0076] Then, the above-mentioned composite precursor slurry was granulated using a centrifugal spray dryer. The atomization method adopted was a dual-fluid pneumatic atomizing nozzle, with the inlet temperature set at 220°C, the outlet temperature at 110°C, and the atomization pressure at 0.25 MPa. The precursor particles were then collected.
[0077] Finally, the precursor particles were heated to 800°C in a muffle furnace at a rate of 5°C / min and held for 2 hours. Then, the temperature was increased to 1150°C at a rate of 5°C / min and held for 4 hours. After that, the particles were allowed to cool naturally to obtain spherical silicon oxide particles.
[0078] Comparative Example 3
[0079] Weigh 1000g of silica sol with a solid content of 30wt.% (average particle size of SiO2 is 55nm), add 0.7g of lithium nitrate and 2.5g of boric acid in sequence while stirring, continue mechanical stirring for 2 hours at a stirring speed of 300 rpm, and after stirring evenly, adjust the pH to 3.5 with 2% nitric acid to obtain the composite precursor slurry.
[0080] Then, the above-mentioned composite precursor slurry was granulated using a centrifugal spray dryer. The atomization method adopted was a dual-fluid pneumatic atomizing nozzle, with the inlet temperature set at 220°C, the outlet temperature at 110°C, and the atomization pressure at 0.25 MPa. The precursor particles were then collected.
[0081] Finally, the precursor particles were heated to 800°C in a muffle furnace at a rate of 5°C / min and held for 2 hours. Then, the temperature was increased to 1150°C at a rate of 5°C / min and held for 4 hours. After that, the particles were allowed to cool naturally to obtain spherical silicon oxide particles.
[0082] Comparative Example 4
[0083] Weigh 1000g of silica sol with a solid content of 30wt.% (average particle size of SiO2 is 55nm), add 1.6g of aluminum nitrate and 2.5g of boric acid in sequence while stirring, continue mechanical stirring for 2 hours at a stirring speed of 300 rpm, and after stirring evenly, adjust the pH to 3.5 with 2% nitric acid to obtain the composite precursor slurry.
[0084] Then, the above-mentioned composite precursor slurry was granulated using a centrifugal spray dryer. The atomization method adopted was a dual-fluid pneumatic atomizing nozzle, with the inlet temperature set at 220°C, the outlet temperature at 110°C, and the atomization pressure at 0.25 MPa. The precursor particles were then collected.
[0085] Finally, the precursor particles were heated to 800°C in a muffle furnace at a rate of 5°C / min and held for 2 hours. Then, the temperature was increased to 1150°C at a rate of 5°C / min and held for 4 hours. After that, the particles were allowed to cool naturally to obtain spherical silicon oxide particles.
[0086] The silica particles obtained in the above embodiments and comparative examples were subjected to performance testing, wherein... Figure 2 This is a particle size distribution diagram of the silica particles prepared in Example 1. Figure 3 This is an isothermal adsorption-desorption curve of the silica particles prepared in Example 1. Figure 4 The isothermal adsorption-desorption curves of the silica particles prepared in Comparative Example 1 are shown in Table 1. As can be seen from the comparison, the silica particles prepared in Example 1 have lower porosity and lower specific surface area. The specific test results are shown in Table 1.
[0087] Table 1
[0088]
[0089] As shown in Table 1, this application, by introducing doping elements composed of alkali metals, aluminum, and boron, effectively eliminates the porosity inside the spray-granulated particles through a liquid-phase sintering mechanism at a temperature far below that of pure silicon oxide, achieving a silicon oxide particle density of 2.18 g / cm³. 3 The above is close to the theoretical density of silicon dioxide particles, 2.2 g / cm³. 3 Meanwhile, this results in the silica particles prepared in this application having a compressive strength of over 150 MPa, exhibiting excellent mechanical strength and being less prone to breakage during transportation and mixing, thus ensuring the stability of the product's particle size distribution.
[0090] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0091] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.
Claims
1. A method for preparing silica particles, characterized in that, Includes the following steps: A silica precursor is mixed with a water-soluble alkali metal salt, a water-soluble aluminum salt, and boric acid, and the pH is adjusted to acidic to obtain a composite precursor slurry. The composite precursor slurry was spray-granulated to obtain precursor particles. The precursor particles were calcined at high temperature to obtain silicon oxide particles.
2. The method for preparing silica particles according to claim 1, characterized in that, The water-soluble alkali metal salt is selected from water-soluble lithium salts; And / or, the water-soluble aluminum salt is selected from at least one of aluminum nitrate, aluminum chloride, aluminum sulfate, and aluminum isopropoxide.
3. The method for preparing silica particles according to claim 2, characterized in that, The water-soluble lithium salt is selected from at least one of lithium carbonate, lithium nitrate, and lithium acetate.
4. The method for preparing silica particles according to claim 1, characterized in that, The precursor particles contain 0.05% to 2% by mass of alkali metal compounds. And / or, the mass fraction of aluminum compound in the precursor particles is 0.01% to 1%; And / or, the precursor particles contain 0.01% to 3% by mass of boron compounds.
5. The method for preparing silica particles according to claim 1, characterized in that, The silica precursor is selected from silica sol, with a particle size of 30nm to 100nm and a solid content of 20wt% to 40wt%.
6. The method for preparing silica particles according to claim 1, characterized in that, In the step of adjusting the pH to acidic, the pH is controlled between 1 and 5.
7. The method for preparing silica particles according to claim 1, characterized in that, In the spray granulation step, the atomization pressure is 0.2 MPa to 0.4 MPa, the inlet temperature is 180°C to 250°C, and the outlet temperature is 90°C to 120°C.
8. The method for preparing silica particles according to claim 1, characterized in that, In the high-temperature calcination step, the heating rate is 2℃ / min to 10℃ / min, the calcination temperature is 1050℃ to 1200℃, and the holding time is 1 hour to 10 hours.
9. The method for preparing silica particles according to claim 1, characterized in that, In the high-temperature roasting step, the temperature is first raised to 500°C to 800°C at a heating rate of 2°C / min to 10°C / min, and held for 1 hour to 4 hours. Then, the temperature is raised to 1050°C to 1200°C at a heating rate of 2°C / min to 10°C / min, and held for 1 hour to 10 hours.
10. A silica particle obtained by the preparation method according to any one of claims 1 to 9.