Zero-hydroxyl micron-sized silicon dioxide particle flame synthesis method and device

Abstract

The invention discloses a zero-hydroxyl micron-sized silicon dioxide particle flame synthesis method and device, and the method comprises the following steps: dry air enters a reactor, wet air in the reactor is discharged, and a silicon-containing precursor, oxygen and fuel enter a combustor mounted at the top of the reactor; flame generated by combustion is sprayed into the reaction cavity and primary silicon dioxide particles are generated; the variable-frequency air blower blows air upwards and enters the reaction cavity through the conical net-shaped fairing, primary silicon dioxide particles suspend under the action of upward wind force and continuously collide, coalesce and grow to final silicon dioxide particles, and the final silicon dioxide particles fall into the bottom of the reaction cavity under the action of gravity. According to the method, the particle size of the silicon dioxide particles is regulated and controlled by adjusting parameters such as the air speed and the flame temperature of the air blower, the micron-sized silicon dioxide particles with the required size are obtained, a silicon-containing precursor and fuel which do not contain hydrogen elements are adopted, meanwhile, water-containing air of a reaction system is exhausted through dry air, and then the purpose of eliminating hydroxyl is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of silica synthesis, and particularly relates to a method and device for flame synthesis of zero-hydroxyl, micron-sized silica particles. Background Art

[0002] High-purity silica particles are the basic materials for preparing quartz crucibles and quartz glass. With the rapid development of the semiconductor and photovoltaic industries, the demand for quartz crucibles and quartz glass is increasing, which significantly increases the demand for high-purity silica particles.

[0003] Currently, the preparation of high-purity silica particles mainly relies on the purification of quartz ore and chemical synthesis methods. The purification process of quartz ore is complex, and it is difficult to achieve the purity requirements of the inner layer sand of quartz crucibles (purity reaching 99.998%), and the price of quartz ore is expensive; chemical methods include flame synthesis, sol-gel, etc. Among them, the flame synthesis method generally generates silica particles through the combustion reaction of silicon-containing precursors in a high-temperature flame, with extremely high purity (reaching over 99.999%) and scalable production, but the generated silica particles have too small particle size (nanoscale) and high hydroxyl content, which are not suitable for the production of traditional quartz crucibles. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides a method and device for flame synthesis of zero-hydroxyl, micron-sized silica particles. By adjusting parameters such as the air speed of the blower and the flame temperature, the particle size of the silica particles is regulated to obtain micron-sized silica particles of the required size. A silicon-containing precursor and fuel without hydrogen element are used, and at the same time, the water-containing air in the reaction system is discharged through dry air, thereby achieving the purpose of eliminating hydroxyl groups.

[0005] To solve the above technical problems, the first aspect of the present invention provides a method for flame synthesis of zero-hydroxyl, micron-sized silica particles, including the following steps: S1. Dry air enters the reactor to discharge the wet air inside the reactor. A silicon-containing precursor, oxygen, and fuel enter the burner installed at the top of the reactor, and the generated flame is vertically sprayed downward into the reaction cavity located inside the reactor to generate primary silica particles; Wherein, both the silicon-containing precursor and the fuel do not contain hydrogen element; S2. A variable-frequency blower located at the center of the bottom of the reaction cavity blows air upward and enters the reaction cavity through a conical mesh rectifying cover. The primary silica particles are suspended in the reaction cavity under the upward wind force and continuously collide, coalesce, and grow into final silica particles, and fall to the bottom of the reaction cavity under the action of gravity; The air speed of the blower is: ; where g is the acceleration due to gravity (m / s 2 ), ρ p and ρ are the density of the final silica particles (kg / m 3 ) and the density of dry air (kg / m 3 ), dp is the diameter of the final silica particles (m), C D is the drag coefficient, with a value of 25.

[0006] In the present invention, a variable-frequency blower blows air upward and enters the reaction cavity through a fairing, acting on the primary silica particles generated by combustion, increasing the collision probability and residence time of the primary silica particles to increase the particle size. When the particle size reaches the micron level, it falls to the bottom of the reaction cavity under the action of gravity. The wind speed of the blower is calculated by a formula, and the particle size of the silica particles is controlled by adjusting the wind speed of the blower. Dry air is introduced into the reactor to remove the moisture in the reactor, and a silicon-containing precursor and a fuel without hydrogen element are used, so that no hydrogen-containing substances are generated in the combustion products, avoiding the presence of hydroxyl groups in the silica particles, and the purity of the obtained silica particles is as high as over 99.998%.

[0007] Furthermore, the silicon-containing precursor enters the burner carried by a carrier gas, and the carrier gas is nitrogen or argon.

[0008] Furthermore, the diameter of the primary silica particles is 0.1 - 1 μm, and the diameter of the final silica particles is 10 μm or more.

[0009] Furthermore, the silicon-containing precursor is SiCl4 or SiF4, and the fuel is CO or CS2.

[0010] Furthermore, the purity of the silicon-containing precursor, oxygen, and fuel is all above 99.99%.

[0011] Furthermore, the wind speed of the blower is 0.1 - 0.1 m / s.

[0012] Furthermore, the equivalence ratio of the fuel and oxygen is 0.5 - 0.8.

[0013] Furthermore, the temperature of the flame is 800 - 1500 °C.

[0014] In the present invention, by adjusting the equivalence ratio of the fuel and oxygen, the flame temperature is reduced to increase the size of the initial silica nanoparticles.

[0015] Further, the conical angle of the conical mesh fairing is 60°-120°, the length and width dimensions of the mesh are independently 0.1-0.5 mm, and the mesh size of the upper part of the conical mesh fairing is smaller than that of the lower part. Among them, the upper part is 40%-60% of the height of the fairing, and the rest is the lower part. The setting of the upper-fine and lower-coarse mesh of the fairing makes the wind speed in the reaction cavity uneven, thus forming a vortex, and the wind speed at the periphery is greater than that at the center. The residence time of the particles in the reaction cavity increases, and the collision probability becomes larger, which is convenient for the formation of large particles.

[0016] Further, the silicon-containing precursor, oxygen, and fuel are respectively input via the central channel of the burner, the sub-central channel surrounding the central channel, and the outer channel surrounding the sub-central channel.

[0017] The second aspect of the present invention provides a zero-hydroxyl, micron-sized silica particle flame synthesis device for implementing the synthesis method described in the first aspect, including a reactor and a reaction cavity located inside the reactor; A burner installed on the reactor is provided directly above the top opening of the reaction cavity, a conical mesh fairing is installed at the bottom opening of the reaction cavity, and a variable-frequency blower is provided below the conical mesh fairing; A dry air inlet and an exhaust port are provided in the middle of the reactor. The dry air inlet is respectively connected to a dryer and a blower, and the exhaust port is connected to an induced draft fan.

[0018] Further, the burner is a multi-channel annular burner, including a central channel, a sub-central channel surrounding the central channel, and an outer channel surrounding the sub-central channel.

[0019] Further, it also includes a blower air inlet pipe extending from the bottom of the reaction cavity into the reaction cavity. The conical mesh fairing is installed at the top of the blower air inlet pipe, and the bottom is hermetically connected to the reaction cavity.

[0020] The beneficial effects of the present invention: The present invention blows air upward through a variable-frequency blower and enters the reaction cavity through the fairing, acting on the primary silica particles generated by combustion, increasing the collision probability and residence time of the primary silica particles to increase the particle size. When it reaches the micron level, it falls to the bottom of the reaction cavity under the action of gravity. The wind speed of the blower is calculated by a formula, and the particle size of the silica particles is controlled by adjusting the wind speed of the blower.

[0021] The present invention adjusts the equivalence ratio of fuel and oxygen to reduce the flame temperature in order to increase the size of the initial silica nanoparticles.

[0022] Through the setting of the upper-thin and lower-thick grid of the fairing in the present invention, the wind speed in the reaction cavity is uneven, thus forming a vortex, and the wind speed at the periphery is greater than that at the center. The residence time of particles in the reaction cavity increases, and the collision probability becomes larger, facilitating the formation of large particles.

[0023] In the present invention, dry air is introduced into the reactor to discharge the moisture in the reactor, and a silicon-containing precursor and a fuel without hydrogen element are used, so that no hydrogen-containing substances are generated in the combustion products, avoiding the presence of hydroxyl groups in the silicon dioxide particles. The purity of the obtained silicon dioxide particles is as high as over 99.998%. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0025] Figure 1 is a schematic structural diagram of a zero-hydroxyl, micron-sized silicon dioxide particle flame synthesis device of the present invention; Figure 2 is a schematic structural diagram of the fairing of the present invention; Explanation of the reference numerals in the drawings: 1. Reactor, 2. Reaction cavity, 3. Burner, 31. Central channel, 32. Sub-central channel, 33. External channel, 4. Fairing, 5. Variable-frequency blower, 6. Dryer, 7. Blower, 8. Induced draft fan, 9. Blower intake pipe. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The technical solutions of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0027] This embodiment relates to a zero-hydroxyl, micron-sized silicon dioxide particle flame synthesis device. Refer to Figure 1 , which includes a reactor 1 and a reaction cavity 2 located inside the reactor 1; a burner 3 installed on the reactor 1 is arranged directly above the top opening of the reaction cavity 2, and a conical mesh fairing 4 is installed at the bottom opening of the reaction cavity 2. Refer to Figure 2 , the grid of the fairing 4 is set with upper-thin and lower-thick, and a variable-frequency blower 5 is arranged below the conical mesh fairing 4; a dry air inlet and an exhaust port are arranged in the middle of the reactor 1. The dry air inlet is respectively connected to a dryer 6 and a blower 7, and the exhaust port is connected to an induced draft fan 8.

[0028] As a preferred embodiment, the burner 3 is a multi-channel annular burner 3, including a central channel 31, a sub-central channel 32 surrounding the central channel 31, and an external channel 33 surrounding the sub-central channel 32.

[0029] As a preferred embodiment, it further includes a blower air inlet pipe 9 extending from the bottom of the reaction chamber 2 into the reaction chamber 2. The conical mesh rectifying hood 4 is installed at the top of the blower air inlet pipe 9, and the bottom is hermetically connected to the reaction chamber 2.

[0030] Another embodiment relates to a method for flame synthesis of zero-hydroxyl, micron-sized silica particles. Using the device described in the above embodiment, it includes the following steps: S1. Dry air enters the reactor 1 to discharge the wet air in the reactor 1. A silicon precursor, oxygen, and fuel enter the burner 3 installed at the top of the reactor 1. Referring to Figure 1 the device shown, the flame generated by combustion is vertically sprayed downward into the reaction chamber 2 located in the reactor 1 to generate primary silica particles; Among them, both the silicon precursor and the fuel do not contain hydrogen elements; S2. The variable-frequency blower 5 located at the central position at the bottom of the reaction chamber 2 blows air upward and enters the reaction chamber 2 through the conical mesh rectifying hood 4. The primary silica particles are suspended in the reaction chamber 2 under the upward wind force and continuously collide, coalesce, and grow into final silica particles, and fall to the bottom of the reaction chamber 2 under the action of gravity; The wind speed calculation formula of the blower 5 is: ; where g is the acceleration due to gravity (m / s 2 ), ρ p and ρ are the density of the final silica particles (kg / m 3 ) and the density of dry air (kg / m 3 ) respectively, dp is the diameter of the final silica particles (m), C D is the drag coefficient, with a value of 25.

[0031] In this embodiment, an inverter blower blows air upward and enters the reaction cavity through a fairing, acting on the primary silica particles generated by combustion, increasing the collision probability and residence time of the primary silica particles to increase the particle size. When the particle size reaches the micron level, the particles fall to the bottom of the reaction cavity under the action of gravity. The wind speed of the blower is calculated by a formula, and the particle size of the silica particles is controlled by adjusting the wind speed of the blower. Dry air is introduced into the reactor to remove the moisture in the reactor, and a silicon-containing precursor and a fuel without hydrogen element are used, so that no hydrogen-containing substances are generated in the combustion products, avoiding the presence of hydroxyl groups in the silica particles, and the purity of the obtained silica particles is as high as over 99.998%.

[0032] As a preferred embodiment, the silicon-containing precursor enters the burner carried by a carrier gas, and the carrier gas is nitrogen or argon; the purities of the silicon-containing precursor, oxygen and fuel are all above 99.99%; the silicon-containing precursor is SiCl4 or SiF4, and the fuel is CO or CS2; the equivalence ratio of the fuel and oxygen is 0.5 - 0.8; the wind speed of the blower is 0.1 - 0.1 m / s; the temperature of the flame is 800 - 1500 °C. In the present invention, by adjusting the equivalence ratio of the fuel and oxygen, the flame temperature is reduced to increase the size of the initial silica nanoparticles. The diameter of the primary silica particles is 0.1 - 1 μm, and the diameter of the final silica particles is above 10 μm.

[0033] As a preferred embodiment, the cone angle of the conical mesh fairing is 60° - 120°, the length and width of the mesh are independently 0.1 - 0.5 mm, and the mesh size of the upper part of the conical mesh fairing is smaller than that of the lower part, where the upper part is 40% - 60% of the height of the fairing, and the rest is the lower part.

[0034] As a preferred embodiment, the silicon-containing precursor, oxygen and fuel are respectively input through the central channel of the burner, the sub-central channel surrounding the central channel, and the outer channel surrounding the sub-central channel.

[0035] Example 1

[0036] This example relates to a method for flame synthesis of zero-hydroxyl, micron-sized silica particles, which includes the following steps: (1) External air is sent into the reactor after passing through a blower and a dryer, and the wet air in the reactor is completely removed; subsequently, the SiCl4 precursor enters the central channel of the multi-channel annular burner carried by argon, oxygen and CO fuel enter the burner from the sub-central and outer channels of the burner respectively, and combustion generates a flame. The equivalence ratio of the fuel and oxygen is 0.8, the flame temperature is 1300 °C, and the particle size of the generated initial silica particles is about 0.15 μm.

[0037] (2) The initial silica particles enter the reaction chamber and are suspended in the upper part of the reaction chamber under the upward wind force of the blower at the lower part of the reaction chamber. The wind speed of the blower blowing upward is 0.1 m / s, the cone angle of the fairing is 60°, the mesh size of the upper part of the fairing is 0.1 mm, and the lower size is 0.2 mm, where both the upper and lower parts are half of the height of the fairing. The suspended silica particles in the reaction chamber undergo processes of collision, coalescence, and growth until the size reaches 10 μm, and then they fall to the bottom of the reaction chamber under the action of gravity, while the small particles still remain suspended in the chamber. The deposited micron-sized silica particles are collected from the bottom of the second chamber. The impurity content and hydroxyl content are tested by ICP-OES and ESR / EPR. Among them, the total impurity content is 15.45 mg / kg, that is, the impurity content is 0.001545%, indicating that the purity of the silica particles is as high as over 99.998%, and the hydroxyl (OH) content is zero.

[0038] Example 2

[0039] This example relates to a method for flame synthesis of zero-hydroxyl, micron-sized silica particles, which includes the following steps: (1) The external air is sent into the reactor after passing through the blower and the dryer, and the wet air in the reactor is completely removed; subsequently, the SiCl4 precursor enters the central channel of the multi-channel annular burner under the carrier of argon, and oxygen and CO fuel enter the burner from the sub-central and external channels of the burner respectively and burn to produce a flame. The equivalence ratio of the fuel and oxygen is 0.5, the flame temperature is 800 °C, and the particle size of the generated initial silica particles is about 0.3 μm.

[0040] (2) The initial silica particles enter the reaction chamber and are suspended in the upper part of the reaction chamber under the upward wind force of the blower at the lower part of the reaction chamber. The wind speed of the blower blowing upward is 0.3 m / s, the cone angle of the fairing is 120°, the mesh size of the upper part of the fairing is 0.3 mm, and the lower size is 0.5 mm, where both the upper and lower parts are half of the height of the fairing. The suspended silica particles in the reaction chamber undergo processes of collision, coalescence, and growth until the size reaches about 90 μm, and then they fall to the bottom of the reaction chamber under the action of gravity, while the small particles still remain suspended in the chamber. The deposited micron-sized silica particles are collected from the bottom of the second chamber. The impurity content and hydroxyl content are tested by ICP-OES and ESR / EPR. Similar to Example 1, the purity of the silica particles is as high as over 99.998%, and the hydroxyl (OH) content is zero.

[0041] Example 3

[0042] This example relates to a method for flame synthesis of zero-hydroxyl, micron-sized silica particles, which includes the following steps: (1) The external air is sent into the reactor after passing through the blower and the dryer, and the wet air in the reactor is completely removed; subsequently, the SiCl4 precursor enters the central channel of the multi-channel annular burner under the carrier of argon, oxygen and CO fuel enter the burner from the sub-central and outer channels of the burner respectively, and combustion generates a flame. The equivalence ratio of the fuel and oxygen is 0.6, the flame temperature is 1000 °C, and the particle size of the initially generated silica particles is about 0.2 μm.

[0043] (2) The initially generated silica particles enter the reaction cavity and are suspended in the upper part of the reaction cavity under the upward wind force of the blower at the lower part of the reaction cavity. The wind speed of the blower blowing upward is 0.2 m / s, the cone angle of the fairing is 80°, the mesh size of the upper part of the fairing is 0.2 mm, and the lower size is 0.3 mm, where both the upper and lower parts are half of the height of the fairing. The suspended silica particles in the reaction cavity experience the processes of collision, coalescence and growth until the size reaches about 40 μm, and then fall to the bottom of the reaction cavity under the action of gravity, while the small particles still remain suspended in the cavity. The deposited micron-sized silica particles are collected from the bottom of the second cavity, and the impurity content and hydroxyl content are tested by ICP-OES and ESR / EPR. Similar to Example 1, the purity of the silica particles is as high as over 99.998%, and the hydroxyl (OH) content is zero.

[0044] Example 4

[0045] This example relates to a method for flame synthesis of zero-hydroxyl, micron-sized silica particles, which includes the following steps: (1) The external air is sent into the reactor after passing through the blower and the dryer, and the wet air in the reactor is completely removed; subsequently, the SiF4 precursor enters the central channel of the multi-channel annular burner under the carrier of argon, oxygen and CS2 fuel enter the burner from the sub-central and outer channels of the burner respectively, and combustion generates a flame. The equivalence ratio of the fuel and oxygen is 0.8, the flame temperature is 1500 °C, and the particle size of the initially generated silica particles is about 0.1 μm.

[0046] (2) The initial silica particles enter the reaction chamber and are suspended in the upper part of the reaction chamber under the upward wind force of the blower at the lower part of the reaction chamber. The wind speed of the blower blowing upward is 0.1 m / s, the cone angle of the fairing is 60°, the grid size of the upper part of the fairing is 0.1 mm, and the lower size is 0.3 mm, where both the upper and lower parts are half of the height of the fairing. The suspended silica particles in the reaction chamber undergo processes of collision, coalescence, and growth until the size reaches 10 μm, and then fall to the bottom of the reaction chamber under the action of gravity, while the small particles still remain suspended in the chamber. The deposited micron-sized silica particles are collected from the bottom of the second chamber, and the impurity content and hydroxyl content are tested by ICP-OES and ESR / EPR. Similar to Example 1, the purity of the silica particles is as high as over 99.998%, and the hydroxyl (OH) content is zero.

[0047] Example 5

[0048] This example relates to a method for flame synthesis of zero-hydroxyl, micron-sized silica particles, including the following steps: (1) External air is sent into the reactor after passing through a blower and a dryer, and the wet air in the reactor is completely removed; subsequently, the SiF4 precursor enters the central channel of the multi-channel annular burner under the carrier of argon, and oxygen and CS2 fuel enter the burner from the sub-central and outer channels of the burner respectively and burn to produce a flame. The equivalence ratio of the fuel and oxygen is 0.5, the flame temperature is 900 °C, and the particle size of the generated initial silica particles is about 0.25 μm.

[0049] (2) The initial silica particles enter the reaction chamber and are suspended in the upper part of the reaction chamber under the upward wind force of the blower at the lower part of the reaction chamber. The wind speed of the blower blowing upward is 0.25 m / s, the cone angle of the fairing is 120°, the grid size of the upper part of the fairing is 0.3 mm, and the lower size is 0.5 mm, where both the upper and lower parts are half of the height of the fairing. The suspended silica particles in the reaction chamber undergo processes of collision, coalescence, and growth until the size reaches about 60 μm, and then fall to the bottom of the reaction chamber under the action of gravity, while the small particles still remain suspended in the chamber. The deposited micron-sized silica particles are collected from the bottom of the second chamber, and the impurity content and hydroxyl content are tested by ICP-OES and ESR / EPR. Similar to Example 1, the purity of the silica particles is as high as over 99.998%, and the hydroxyl (OH) content is zero.

[0050] Example 6

[0051] This example relates to a method for flame synthesis of zero-hydroxyl, micron-sized silica particles, including the following steps: (1)The external air is sent into the reactor after passing through the blower and the dryer, and the wet air in the reactor is completely exhausted. Subsequently, the SiF4 precursor enters the central channel of the multi-channel annular burner under the carrier of argon. Oxygen and CS2 fuel enter the burner from the sub-center and the outer channel of the burner respectively and burn to produce a flame. The equivalence ratio of the fuel to oxygen is 0.7, the flame temperature is 1400 °C, and the particle size of the initially generated silica particles is about 0.12 μm.

[0052] (2)The initially generated silica particles enter the reaction cavity and are suspended in the upper part of the reaction cavity under the upward wind force of the blower at the lower part of the reaction cavity. The wind speed of the blower blowing upward is 0.15 m / s, the cone angle of the fairing is 70°, the mesh size of the upper part of the fairing is 0.1 mm, and the lower size is 0.2 mm, where both the upper and lower parts are half of the height of the fairing. The suspended silica particles in the reaction cavity experience processes of collision, coalescence, and growth until the size reaches about 24 μm, and then fall to the bottom of the reaction cavity under the action of gravity, while the small particles still remain suspended in the cavity. The deposited micron-sized silica particles are collected from the bottom of the second cavity, and the impurity content and hydroxyl content are tested by ICP-OES and ESR / EPR. Similar to Example 1, the purity of the silica particles is as high as over 99.998%, and the hydroxyl (OH) content is zero.

[0053] In summary, the present invention regulates parameters such as the wind speed of the blower, the ratio of oxygen to fuel, the mesh of the fairing, and the flame temperature to control the particle size of the silica particles, obtains micron-sized silica particles of the required size, uses a silicon-containing precursor and fuel without hydrogen element, and at the same time discharges the water-containing air in the reaction system through dry air, thereby achieving the purpose of eliminating hydroxyl groups, and the purity of the silica particles is as high as over 99.998%.

[0054] The present invention has been described in detail above in combination with specific embodiments and exemplary examples, but these descriptions should not be construed as limiting the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications, or improvements can be made to the technical solutions and their implementation manners of the present invention, and these all fall within the scope of the present invention. The protection scope of the present invention is subject to the appended claims.

Claims

1. A method for flame synthesis of zero-hydroxyl, micron-sized silica particles, characterized in that, It includes the following steps: S1. Dry air enters the reactor to discharge the wet air inside the reactor. A silicon precursor, oxygen, and fuel enter a burner installed at the top of the reactor. The flame generated by combustion is vertically sprayed downward into the reaction cavity located inside the reactor to generate primary silica particles; Among them, both the silicon precursor and the fuel do not contain hydrogen elements; S2. A variable-frequency blower located at the center of the bottom of the reaction cavity blows air upward and enters the reaction cavity through a conical mesh rectifying cover. The primary silica particles are suspended in the reaction cavity under the action of the upward wind force and continuously collide, coalesce, and grow into final silica particles, and fall to the bottom of the reaction cavity under the action of gravity; The wind speed of the blower is: ; where g is the acceleration due to gravity, ρ p and ρ are the density of the final silica particles and the density of dry air, respectively, dp is the diameter of the final silica particles, C D is the drag coefficient, with a value of 25.

2. The method for flame synthesis of zero-hydroxyl, micron-sized silica particles as claimed in claim 1, wherein The diameter of the primary silica particles is 0.1 - 1 μm, and the diameter of the final silica particles is more than 10 μm.

3. The flame synthesis method of zero-hydroxy, micron-sized silica particles as described in claim 1, characterized in that, The silicon precursor is SiCl4 or SiF4, and the fuel is CO or CS2.

4. The method for flame synthesis of zero-hydroxy, micron-sized silica particles as described in claim 1, wherein, The equivalence ratio of the fuel to oxygen is 0.5 - 0.

8.

5. The method for flame synthesis of zero-hydroxy, micron-sized silica particles according to claim 1, characterized in that, The cone angle of the conical mesh rectifying cover is 60° - 120°, the length and width dimensions of the grid are independently 0.1 - 0.5 mm, and the grid size of the upper part of the conical mesh rectifying cover is smaller than that of the lower part.

6. The method for flame synthesis of zero-hydroxyl, micron-sized silica particles as claimed in claim 1, wherein, The temperature of the flame is 800 - 1500 °C.

7. The method for flame synthesis of zero-hydroxy, micron-sized silica particles according to claim 1, characterized in that, The silicon precursor, oxygen, and fuel are respectively input through the central channel of the burner, the sub-central channel surrounding the central channel, and the outer channel surrounding the sub-central channel.

8. A flame synthesis device for zero-hydroxyl, micron-sized silica particles, characterized in that, For implementing the synthesis method according to any one of claims 1 - 7, it includes a reactor and a reaction cavity located inside the reactor; A burner installed on the reactor is arranged directly above the opening at the top of the reaction cavity. A conical mesh rectifying cover is installed at the opening at the bottom of the reaction cavity, and a variable-frequency blower is arranged below the conical mesh rectifying cover; A dry air inlet and an exhaust port are arranged in the middle of the reactor. The dry air inlet is respectively connected to a dryer and a blower, and the exhaust port is connected to an induced draft fan.

9. The zero-hydroxy, micron-sized silica particle flame synthesis device according to claim 8, wherein, The burner is a multi-channel annular burner, including a central channel, a sub-central channel surrounding the central channel, and an outer channel surrounding the sub-central channel.

10. The zero-hydroxy, micron-sized silica particle flame synthesis device according to claim 8, characterized in that, It also includes a blower intake pipe extending from the bottom of the reaction cavity into the reaction cavity. The conical mesh rectifying cover is installed at the top of the blower intake pipe, and the bottom is hermetically connected to the reaction cavity.

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