A flame synthesis method and device for zero-hydroxyl, micron-sized silicon dioxide particles

Abstract

The present invention discloses a flame synthesis method and device for zero hydroxyl group and micron-sized silica particles, comprising the following steps: dry air enters a reactor to discharge wet air in the reactor, a silicon-containing precursor, oxygen and fuel enter a burner installed on the top of the reactor, and the flame generated by the combustion is sprayed into the reaction chamber and generates primary silica particles; a variable frequency blower blows air upward through a conical mesh fairing into the reaction chamber, and the primary silica particles are suspended under the action of the upward wind and continuously collide, aggregate and grow into final silica particles, which fall to the bottom of the reaction chamber under the action of gravity. The present invention regulates the particle size of the silica particles by adjusting parameters such as the wind speed and flame temperature of the blower, obtains micron-sized silica particles of the required size, adopts a silicon-containing precursor and fuel that does not contain hydrogen element, and simultaneously discharges the water-containing air of the reaction system through dry air, thereby achieving the purpose of eliminating hydroxyl groups.

Description

Technical Field

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

[0002] High-purity silica particles are the basic material for preparing quartz crucibles and quartz glass. With the rapid development of the semiconductor and photovoltaic industries, more and more quartz crucibles and quartz glass are needed, which has significantly increased the demand for high-purity silica particles.

[0003] Currently, high-purity silica particles are primarily produced through quartz ore purification and chemical synthesis. Quartz ore purification is complex, making it difficult to achieve the purity required for the inner sand layer of a quartz crucible (99.998%). Quartz ore is also expensive. Chemical methods include flame synthesis and sol-gel synthesis. Flame synthesis typically produces silica particles through a high-temperature flame combustion reaction of a silicon-containing precursor. While extremely pure (over 99.999%), the resulting silica particles are suitable for scalable production. However, the resulting silica particles are too small (nanoscale) and have a high hydroxyl content, making them unsuitable for use in traditional quartz crucible production. Summary of the Invention

[0004] In response to the deficiencies in the prior art, the present invention provides a flame synthesis method and apparatus for producing zero-hydroxyl, micron-sized silica particles. The method controls the particle size of the silica particles by adjusting parameters such as the blower wind speed and flame temperature to obtain micron-sized silica particles of a required size. Hydrogen-free silicon-containing precursors and fuels are used, and water-containing air in the reaction system is exhausted through dry air, thereby eliminating hydroxyl groups.

[0005] In order to solve the above technical problems, the first aspect of the present invention provides a flame synthesis method for zero-hydroxyl, micron-sized silica particles, comprising the following steps:

[0006] S1, dry air enters the reactor and the wet air in the reactor is discharged, and the silicon-containing precursor, oxygen and fuel enter the burner installed on the top of the reactor. The flame generated by the combustion is sprayed vertically downward into the reaction chamber in the reactor to generate primary silica particles;

[0007] Wherein, the silicon-containing precursor and the fuel do not contain hydrogen;

[0008] S2, a variable frequency blower located at the center of the bottom of the reaction chamber blows air upward, and the air enters the reaction chamber through the conical mesh fairing. The primary silica particles are suspended in the reaction chamber under the action of the upward wind and continuously collide, aggregate, and grow into final silica particles, which fall to the bottom of the reaction chamber under the action of gravity;

[0009] The wind speed of the blower is: ;

[0010] Where g is the acceleration due to gravity (m / s 2 ), ρ p and ρ Final silica particle density (kg / m 3 ) and dry air density (kg / m 3 ), dp is the final silica particle diameter (m), C D is the drag coefficient, which takes a value of 25.

[0011] The present invention uses a variable-frequency blower to blow air upward, which enters the reaction chamber through a fairing and acts on the primary silica particles produced by combustion, increasing their collision probability and residence time to increase their particle size. When they reach the micron level, they fall to the bottom of the reaction chamber under the action of gravity. The blower speed is calculated using a formula, and the particle size of the silica particles can be controlled by adjusting the blower speed. Dry air is introduced into the reactor to remove moisture from the reactor, and hydrogen-free silicon precursors and fuels are used to eliminate hydrogen-containing substances in the combustion products, preventing the presence of hydroxyl groups in the silica particles. The resulting silica particles have a purity of over 99.998%.

[0012] Furthermore, the silicon-containing precursor is carried into the burner by a carrier gas, and the carrier gas is nitrogen or argon.

[0013] Furthermore, the diameter of the primary silica particles is 0.1-1 μm, and the diameter of the final silica particles is greater than 10 μm.

[0014] Furthermore, the silicon-containing precursor is SiCl4 or SiF4, and the fuel is CO or CS2.

[0015] Furthermore, the purity of the silicon-containing precursor, oxygen and fuel is above 99.99%.

[0016] Furthermore, the wind speed of the blower is 0.1-0.1 m / s.

[0017] Furthermore, the equivalence ratio of the fuel to oxygen is 0.5-0.8.

[0018] Furthermore, the temperature of the flame is 800-1500°C.

[0019] The present invention adjusts the equivalence ratio of fuel to oxygen to reduce the flame temperature so as to increase the size of initial silicon dioxide nanoparticles.

[0020] Furthermore, the conical mesh fairing has a cone angle of 60°-120°, and the mesh length and width are independently 0.1-0.5 mm. The mesh size of the upper portion of the conical mesh fairing is smaller than that of the lower portion, with the upper portion comprising 40%-60% of the fairing height, and the remainder in the lower portion. The mesh of the fairing is arranged so that it is finer at the top and coarser at the bottom, resulting in uneven wind speed within the reaction chamber, which forms vortices. The wind speed at the periphery is greater than that at the center, increasing the residence time of particles within the reaction chamber and the probability of collision, which facilitates the formation of large particles.

[0021] Furthermore, the silicon-containing precursor, oxygen and fuel are respectively inputted through the central channel of the burner, the sub-central channel surrounding the central channel and the external channel surrounding the sub-central channel.

[0022] The second aspect of the present invention provides a flame synthesis device for zero-hydroxyl, micron-sized silica particles, for implementing the synthesis method described in the first aspect, comprising a reactor and a reaction chamber located in the reactor;

[0023] A burner mounted on the reactor is provided just above the top opening of the reaction chamber, a conical mesh fairing is provided at the bottom opening of the reaction chamber, and a variable frequency blower is provided below the conical mesh fairing;

[0024] A dry air inlet and an exhaust port are provided in the middle of the reactor. The dry air inlet is connected to the dryer and the blower respectively, and the exhaust port is connected to the induced draft fan.

[0025] Furthermore, 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.

[0026] Furthermore, it also includes a blower air inlet pipe extending from the bottom of the reaction chamber into the reaction chamber, the cone-shaped mesh fairing is installed on the top of the blower air inlet pipe, and the bottom is sealed and connected to the reaction chamber.

[0027] Beneficial effects of the present invention:

[0028] The present invention uses a variable frequency blower to blow air upward, and the air enters the reaction chamber through a fairing, acting on the primary silica particles produced by combustion, increasing the collision probability and residence time of the primary silica particles to increase the particle size. When the particles reach the micron level, they fall to the bottom of the reaction chamber under the action of gravity. The wind speed of the blower is calculated using a formula, and the particle size of the silica particles can be controlled by adjusting the wind speed of the blower.

[0029] The present invention adjusts the equivalence ratio of fuel to oxygen to reduce the flame temperature so as to increase the size of initial silicon dioxide nanoparticles.

[0030] The present invention arranges the grid of the fairing to be fine at the top and coarse at the bottom, so that the wind speed in the reaction chamber is uneven, thereby forming a vortex, and the wind speed at the periphery is greater than that at the center, which increases the residence time of particles in the reaction chamber and increases the collision probability, thereby facilitating the formation of large particles.

[0031] The present invention introduces dry air into the reactor to expel moisture from the reactor, and uses silicon-containing precursors and fuels that do not contain hydrogen elements, so that no hydrogen-containing substances are produced in the combustion products, thereby 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

[0032] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 This is a schematic structural diagram of a flame synthesis device for zero-hydroxyl, micron-sized silica particles according to the present invention;

[0034] Figure 2 It is a schematic diagram of the fairing structure of the present invention;

[0035] Explanation of the numbers in the figure: 1. Reactor, 2. Reaction chamber, 3. Burner, 31. Central channel, 32. Sub-central channel, 33. External channel, 4. Fairing, 5. Blower, 6. Dryer, 7. Supply fan, 8. Induced draft fan, 9. Blower air inlet duct. DETAILED DESCRIPTION

[0036] The following will provide a clear and complete description of the technical solutions of the present invention in conjunction with specific embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0037] This embodiment relates to a flame synthesis device for zero-hydroxyl, micron-sized silica particles, referring to Figure 1 , comprising a reactor 1 and a reaction chamber 2 located in the reactor 1; a burner 3 mounted on the reactor 1 is provided just above the top opening of the reaction chamber 2, and a conical mesh fairing 4 is installed at the bottom opening of the reaction chamber 2, Figure 2The mesh of the fairing 4 is set to be fine at the top and coarse at the bottom, and a variable frequency blower 5 is set below the conical mesh fairing 4; a dry air inlet and an exhaust port are set in the middle of the reactor 1, and the dry air inlet is connected to the dryer 6 and the blower 7 respectively, and the exhaust port is connected to the induced draft fan 8.

[0038] 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 outer channel 33 surrounding the sub-central channel 32 .

[0039] As a preferred embodiment, it also includes a blower air inlet pipe 9 extending from the bottom of the reaction chamber 2 into the reaction chamber 2, the cone-shaped mesh fairing 4 is installed on the top of the blower air inlet pipe 9, and the bottom is sealed with the reaction chamber 2.

[0040] Another embodiment relates to a flame synthesis method for zero-hydroxyl, micron-sized silica particles, using the apparatus described in the above embodiment, comprising the following steps:

[0041] S1, dry air enters the reactor 1 and the wet air in the reactor 1 is discharged, and the silicon precursor, oxygen and fuel enter the burner 3 installed on the top of the reactor 1, refer to Figure 1 In the device shown, the flame generated by the combustion sprays vertically downward into the reaction chamber 2 located in the reactor 1 and generates primary silicon dioxide particles;

[0042] Wherein, the silicon-containing precursor and the fuel do not contain hydrogen;

[0043] S2, a variable frequency blower 5 located at the center of the bottom of the reaction chamber 2 blows air upward, and enters the reaction chamber 2 through the conical mesh fairing 4. The primary silica particles are suspended in the reaction chamber 2 under the action of the upward wind and continuously collide, aggregate, and grow into final silica particles, which fall to the bottom of the reaction chamber 2 under the action of gravity;

[0044] The wind speed calculation formula of the blower 5 is: ;

[0045] Where g is the acceleration due to gravity (m / s 2 ), ρ p and ρ Final silica particle density (kg / m 3 ) and dry air density (kg / m 3 ), dp is the final silica particle diameter (m), C D is the drag coefficient, which takes a value of 25.

[0046] In this embodiment, air is blown upward by a variable frequency blower and enters the reaction chamber through a fairing. The air acts on the primary silica particles produced by combustion, increasing their collision probability and residence time to increase their particle size. When the particles reach the micron level, they fall to the bottom of the reaction chamber under the action of gravity. The blower speed is calculated using a formula, and the particle size of the silica particles is controlled by adjusting the blower speed. Dry air is introduced into the reactor to remove moisture from the reactor, and hydrogen-free silicon precursors and fuels are used to eliminate hydrogen-containing substances from the combustion products, preventing the presence of hydroxyl groups in the silica particles. The resulting silica particles have a purity of over 99.998%.

[0047] In a preferred embodiment, the silicon-containing precursor is carried into the burner by a carrier gas, wherein the carrier gas is nitrogen or argon; the purity of the silicon-containing precursor, oxygen, and fuel is 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 to oxygen is 0.5-0.8; the wind speed of the blower is 0.1-0.1 m / s; and the temperature of the flame is 800-1500°C. By adjusting the equivalence ratio of fuel to oxygen and lowering the flame temperature, the present invention increases the size of the initial silica nanoparticles, resulting in a diameter of the primary silica particles of 0.1-1 μm and a diameter of the final silica particles of 10 μm or greater.

[0048] As a preferred embodiment, the cone angle of the conical mesh fairing is 60°-120°, the length and width of the grid are independently 0.1-0.5 mm, and the upper part of the conical mesh fairing is smaller than the lower part of the grid size, wherein the upper part is 40%-60% of the height of the fairing, and the rest is the lower part.

[0049] 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 external channel surrounding the sub-central channel.

[0050] Example 1

[0051] This embodiment relates to a flame synthesis method for zero-hydroxyl, micron-sized silica particles, comprising the following steps:

[0052] (1) External air is sent into the reactor through a blower and a dryer, and the wet air in the reactor is exhausted. Subsequently, the SiCl4 precursor is carried by argon gas into the central channel of the multi-channel annular burner. Oxygen and CO fuel enter the burner from the secondary center and external channels of the burner, respectively, and burn to produce a flame. The equivalent ratio of fuel to oxygen is 0.8, the flame temperature is 1300 ° C, and the particle size of the initial silica particles generated is about 0.15 μm.

[0053] (2) The initial silica particles enter the reaction chamber and are suspended in the upper part of the reaction chamber under the upward force of the blower at the bottom of the reaction chamber. The upward wind speed of the blower is 0.1m / s, the cone angle of the fairing is 60°, the mesh size of the upper part of the fairing is 0.1mm, and the mesh size of the lower part is 0.2mm. The upper and lower parts are both half the height of the fairing. The suspended silica particles in the reaction chamber undergo collision, aggregation, and growth until the size reaches 10μm. Under the action of gravity, they fall to the bottom of the reaction chamber, while small particles 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. The total impurity content is 15.45mg / kg, that is, the impurity content is 0.001545%. It can be seen that the purity of the silica particles is as high as 99.998% or more, and the hydroxyl (OH) content is zero.

[0054] Example 2

[0055] This embodiment relates to a flame synthesis method for zero-hydroxyl, micron-sized silica particles, comprising the following steps:

[0056] (1) External air is sent into the reactor through a blower and a dryer, and the wet air in the reactor is exhausted. Subsequently, the SiCl4 precursor is carried by argon gas into the central channel of the multi-channel annular burner. Oxygen and CO fuel enter the burner from the secondary center and external channels of the burner, respectively, and burn to produce a flame. The equivalent ratio of fuel to oxygen is 0.5, the flame temperature is 800 ° C, and the particle size of the initial silica particles generated is about 0.3 μm.

[0057] (2) 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 bottom of the reaction chamber. The upward wind speed of the blower 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, wherein the upper and lower parts are half the height of the fairing. The suspended silica particles in the reaction chamber undergo a process of collision, aggregation, and growth until the size reaches about 90 μm. Under the action of gravity, they fall to the bottom of the reaction chamber, while small particles remain suspended in the chamber. The deposited micron-sized silica particles are collected from the bottom of the second chamber and tested for impurity content and hydroxyl content by ICP-OES and ESR / EPR. As in Example 1, the purity of the silica particles is as high as 99.998% or more, and the hydroxyl (OH) content is zero.

[0058] Example 3

[0059] This embodiment relates to a flame synthesis method for zero-hydroxyl, micron-sized silica particles, comprising the following steps:

[0060] (1) External air is sent into the reactor through a blower and a dryer, and the wet air in the reactor is exhausted. Then, SiCl4 precursor is carried by argon gas into the central channel of the multi-channel annular burner. Oxygen and CO fuel enter the burner from the secondary center and external channels of the burner, respectively, and burn to produce a flame. The equivalent ratio of fuel to oxygen is 0.6, the flame temperature is 1000 ° C, and the particle size of the initial silica particles generated is about 0.2 μm.

[0061] (2) Initial silica particles enter the reaction chamber and are suspended in the upper part of the reaction chamber under the upward force of the blower at the bottom of the reaction chamber. The upward wind speed of the blower 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 size of the lower part is 0.3 mm, wherein the upper and lower parts are half the height of the fairing. The suspended silica particles in the reaction chamber undergo a process of collision, aggregation, and growth until the size reaches about 40 μm. Under the action of gravity, they fall to the bottom of the reaction chamber, while small particles remain suspended in the chamber. The deposited micron-sized silica particles are collected from the bottom of the second chamber and tested for impurity content and hydroxyl content by ICP-OES and ESR / EPR. As in Example 1, the purity of the silica particles is as high as 99.998% or more, and the hydroxyl (OH) content is zero.

[0062] Example 4

[0063] This embodiment relates to a flame synthesis method for zero-hydroxyl, micron-sized silica particles, comprising the following steps:

[0064] (1) External air is sent into the reactor through a blower and a dryer, and the wet air in the reactor is exhausted. Subsequently, the SiF4 precursor is carried by argon gas into the central channel of the multi-channel annular burner, and oxygen and CS2 fuel enter the burner from the secondary center and external channels of the burner respectively, and burn to produce a flame. The equivalent ratio of fuel to oxygen is 0.8, the flame temperature is 1500℃, and the particle size of the initial silica particles generated is about 0.1μm.

[0065] (2) 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 bottom of the reaction chamber. The upward wind speed of the blower 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 0.3 mm, wherein the upper and lower parts are half the height of the fairing. The suspended silica particles in the reaction chamber undergo a process of collision, aggregation, and growth until the size reaches 10 μm. Under the action of gravity, they fall to the bottom of the reaction chamber, while small particles remain suspended in the chamber. The deposited micron-sized silica particles are collected from the bottom of the second chamber and tested for impurity content and hydroxyl content by ICP-OES and ESR / EPR. As in Example 1, the purity of the silica particles is as high as 99.998% or more, and the hydroxyl (OH) content is zero.

[0066] Example 5

[0067] This embodiment relates to a flame synthesis method for zero-hydroxyl, micron-sized silica particles, comprising the following steps:

[0068] (1) External air is sent into the reactor through a blower and a dryer, and the wet air in the reactor is exhausted. Then, SiF4 precursor is carried by argon gas into the central channel of the multi-channel annular burner, and oxygen and CS2 fuel enter the burner from the secondary center and external channels of the burner respectively, and burn to produce a flame. The equivalent ratio of fuel to oxygen is 0.5, the flame temperature is 900 ° C, and the particle size of the initial silica particles generated is about 0.25 μm.

[0069] (2) Initial silica particles enter the reaction chamber and are suspended in the upper part of the reaction chamber under the upward force of the blower at the bottom of the reaction chamber. The upward wind speed of the blower is 0.25 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, wherein the upper and lower parts are half the height of the fairing. The suspended silica particles in the reaction chamber undergo a process of collision, aggregation, and growth until the size reaches about 60 μm. Under the action of gravity, they fall to the bottom of the reaction chamber, while small particles remain suspended in the chamber. The deposited micron-sized silica particles are collected from the bottom of the second chamber and tested for impurity content and hydroxyl content by ICP-OES and ESR / EPR. As in Example 1, the purity of the silica particles is as high as 99.998% or more, and the hydroxyl (OH) content is zero.

[0070] Example 6

[0071] This embodiment relates to a flame synthesis method for zero-hydroxyl, micron-sized silica particles, comprising the following steps:

[0072] (1) External air is sent into the reactor through a blower and a dryer, and the wet air in the reactor is exhausted. Then, SiF4 precursor is carried by argon gas into the central channel of the multi-channel annular burner, and oxygen and CS2 fuel enter the burner from the secondary center and external channels of the burner respectively, and burn to produce a flame. The equivalent ratio of fuel to oxygen is 0.7, the flame temperature is 1400℃, and the particle size of the initial silica particles generated is about 0.12μm.

[0073] (2) 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 bottom of the reaction chamber. The upward wind speed of the blower 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, wherein the upper and lower parts are half the height of the fairing. The suspended silica particles in the reaction chamber undergo a process of collision, aggregation, and growth until the size reaches about 24 μm. Under the action of gravity, they fall to the bottom of the reaction chamber, while small particles remain suspended in the chamber. The deposited micron-sized silica particles are collected from the bottom of the second chamber and tested for impurity content and hydroxyl content by ICP-OES and ESR / EPR. As in Example 1, the purity of the silica particles is as high as 99.998% or more, and the hydroxyl (OH) content is zero.

[0074] In summary, the present invention controls the particle size of the silica particles by adjusting parameters such as the blower wind speed, the ratio of oxygen to fuel, the fairing grid, and the flame temperature to obtain micron-sized silica particles of the required size. Hydrogen-free silicon-containing precursors and fuels are used, and water-containing air is exhausted from the reaction system through dry air, thereby achieving the purpose of eliminating hydroxyl groups. The purity of the silica particles is as high as over 99.998%.

[0075] The present invention has been described in detail above with reference to specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present invention. Those skilled in the art will appreciate that various equivalent substitutions, modifications, or improvements may be made to the technical solutions and implementations of the present invention without departing from the spirit and scope of the present invention, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A flame synthesis method for zero-hydroxyl, micron-sized silica particles, characterized in that: The device used in the synthesis method includes a reactor and a reaction cavity located in the reactor; A burner mounted on the reactor is provided just above the top opening of the reaction chamber, a conical mesh fairing is provided at the bottom opening of the reaction chamber, 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 connected to the dryer and the blower respectively, and the exhaust port is connected to the induced draft fan; The burner is a multi-channel annular burner, comprising a central channel, a sub-central channel surrounding the central channel, and an outer channel surrounding the sub-central channel; The upper portion of the conical mesh fairing has a smaller mesh size than the lower portion; The synthesis method comprises the following steps: S1, dry air enters the reactor and the wet air in the reactor is discharged, and the silicon-containing precursor, oxygen and fuel enter the burner installed on the top of the reactor. The flame generated by the combustion is sprayed vertically downward into the reaction chamber in the reactor to generate primary silica particles; Wherein, the silicon-containing precursor and the fuel do not contain hydrogen; S2, a variable frequency blower located at the center of the bottom of the reaction chamber blows air upward, and the air enters the reaction chamber through the conical mesh fairing. The primary silica particles are suspended in the reaction chamber under the action of the upward wind and continuously collide, aggregate, and grow into final silica particles, which fall to the bottom of the reaction chamber under the action of gravity; The wind speed of the blower is: ; Where g is the acceleration due to gravity, ρ p and ρ Final silica particle density and dry air density, respectively, dp is the final silica particle diameter, C D is the drag coefficient, which takes a value of 25; The silicon-containing precursor is SiCl4 or SiF4, and the fuel is CO or CS2.

2. The flame synthesis method for zero-hydroxyl, micron-sized silica particles according to claim 1, characterized in that: The diameter of the primary silica particles is 0.1-1 μm, and the diameter of the final silica particles is greater than 10 μm.

3. The flame synthesis method for zero-hydroxyl, micron-sized silica particles according to claim 1, characterized in that: The equivalence ratio of the fuel to oxygen is 0.5-0.

8.

4. The flame synthesis method for zero-hydroxyl, micron-sized silica particles according to claim 1, characterized in that: The cone angle of the conical mesh fairing is 60°-120°, and the length and width of the grid are independently 0.1-0.5 mm.

5. The flame synthesis method for zero-hydroxyl, micron-sized silica particles according to claim 1, characterized in that: The temperature of the flame is 800-1500°C.

6. The flame synthesis method for zero-hydroxyl, micron-sized silica particles according to claim 1, characterized in that: The silicon-containing precursor, oxygen and fuel are respectively inputted through the central channel of the burner, the sub-central channel surrounding the central channel and the external channel surrounding the sub-central channel.

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