A system for preparing spherical silica and a method for preparing the same

Abstract

The application discloses a kind of preparation system of spherical silica and its preparation method, specifically related to the technical field of producing spherical silica;Among them, the system includes: silicon water bag, oxygen delivery pipe, air compressor, smoke cover, dust collector, induced draft fan, storage bin, closed vibrating screen, de-ironer, temporary storage bin, chlorination furnace and hydrogen chloride gas delivery pipe;Preparation method includes the following steps: (1) smelting;(2) oxygen blowing;(3) dust removal screening and de-ironing;(4) purification separation.Affirmative effect: the application provides a kind of preparation system of spherical silica, connection structure is simple, easy to realize, can mass-produce spherical silica micro powder;The application provides a kind of preparation method of spherical silica, reduces raw material cost, both ensures the professional health of on-site staff and production safety, also reduces the equipment cost of producing silica;It is suitable for large-scale industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of producing spherical silicon dioxide, and in particular to a preparation system and method of spherical silicon dioxide. BACKGROUND

[0002] Spherical silicon dioxide is widely used in the fields of aviation, aerospace, fine chemical industry, special ceramics and daily cosmetics due to its superior properties such as high heat resistance, high moisture resistance, high dielectric, high filling capacity, low expansion, low stress, low impurity and low friction coefficient, and is an indispensable high-quality material for substrates and packaging materials of large-scale and super-large scale integrated circuits.

[0003] The patent with application number 202010277674.1 discloses a preparation method of spherical nano-silicon dioxide, which discloses that under the action of electromagnetic waves, oxygen and silicon powder suspended in the oxygen react to obtain spherical nano-silicon dioxide; the wavelength of the electromagnetic wave is 1-150 mm. The present application uses electromagnetic waves with a specific wavelength of 1-150 mm as a reaction energy source, which can simultaneously immerse all powder particles in the reaction system for heating, promote the reaction with oxygen, and generate nano-silicon dioxide microspheres with a purity of 99.9% or above. However, the above-mentioned method has the following problems: 1. The purity of the raw silicon powder in the above-mentioned method is high, and the raw silicon powder needs to be heated or melted and purified, and then ground by dry or wet method to obtain high-purity raw silicon powder; the preparation process is complex, the cost of raw material preparation is high, and the cost of subsequent preparation of nano-sized spherical silicon dioxide powder is high; 2. Using electromagnetic waves for heating, there is ionizing radiation, which poses a great safety hazard to on-site workers, and therefore is not suitable for large-scale industrial production; 3. The dust of silicon powder is explosive dust, and the patent discloses that the silicon powder is introduced into the container chamber to form a certain concentration of floating dust (50-100 g / m 3 ), which belongs to the explosive concentration of dust, and the reaction with oxygen at high temperature is uncontrollable, which is prone to dust explosion and poses a great safety hazard.

[0004] The patent with application number 202410316651.5 discloses a preparation process of sub-micron spherical silicon dioxide, which discloses steps of gas mixing, gas combustion, raw material pretreatment, silicon dioxide preparation and particle collection, and the present application

[0005] The inventive combination gas phase combustion method uses silicon and silicon oxide, silicon nitride as raw materials to prepare sub-micron spherical silica, which has the advantages of small particle size, large specific surface area, high purity, high quality and the like; but the above method has the following problems: 1. The above process for preparing sub-micron spherical silica uses 0.1 micron or so particle size of silica as seed crystal, which has the problem of high purchase cost; at the same time, the raw materials need to be pretreated, and a variety of chemical reagents are used in the pretreatment process, the process is complicated, and the treatment cost is high, so there is a problem of high cost of preparing silica; 2. The temperature in the process of burning and synthesizing sub-micron spherical silica particles is as high as 2500~3000℃, so the inner lining of the reaction furnace requires high refractory material, and the equipment cost for producing and preparing silica is high; 3. The use of flammable and explosive hydrogen-containing fuel (i.e. methane) in the combustion synthesis process has great safety hazards. SUMMARY

[0006] The purpose of the present application is to provide a preparation system for spherical silica powder which has a simple connection structure and can mass-produce spherical silica powder.

[0007] The purpose of the present application is to provide a preparation method for spherical silica powder which has a simple process, is safe to produce and suitable for large-scale industrial production.

[0008] The purpose of the present application is implemented by the following technical scheme: a preparation system for spherical silica, comprising: a silicon water tank, an oxygen delivery pipe and an air compressor; the air compressor and the oxygen delivery pipe are both connected to the gas inlet at the bottom of the silicon water tank; it also includes a smoke hood, a dust collector, a draught fan, a storage bin, a closed vibrating screen, a de-ironing device, a temporary storage bin, a chlorination furnace and a hydrogen chloride gas delivery pipe; the smoke hood is arranged above the silicon water tank, the gas outlet of the smoke hood is connected to the gas inlet of the dust collector through a pipeline, and the gas outlet of the dust collector is connected to the gas inlet of the draught fan through a pipeline; the dust collector, the storage bin, the closed vibrating screen, the de-ironing device and the temporary storage bin are connected in sequence through a pipeline; the discharge outlet of the temporary storage bin is connected to the feed inlet above the chlorination furnace through a pipeline; and the gas outlet of the hydrogen chloride gas delivery pipe is connected to the gas inlet below the chlorination furnace through a pipeline.

[0009] Further, the discharge outlet below the chlorination furnace is connected to the feed inlet of the product storage bin through a pipeline.

[0010] Further, a variable frequency star unloader is arranged on the discharge outlet of the storage bin and the temporary storage bin, respectively.

[0011] Further, the impurity discharge outlet of the closed vibrating screen is connected to the feed inlet of the impurity bin through a pipeline.

[0012] Further, the screen of the closed vibrating screen is a 60-400 mesh screen.

[0013] The object of the present application is achieved by the following technical solution: a preparation method of spherical silicon dioxide, comprising the following steps:

[0014] (1) smelting: mixing silica, wood chips and coal according to a mass ratio of 3:0.8-1.3:1.7-2.4, and then putting the mixture into a submerged arc furnace to perform continuous smelting at a temperature of 1500-1800 ℃, so as to obtain liquid silicon;

[0015] (2) oxygen blowing: loading the liquid silicon in step (1) into a silicon ladle, wherein the temperature of the liquid silicon in the silicon ladle is 1530-1600 ℃; introducing a mixed gas of compressed air and oxygen into the bottom of the silicon ladle, wherein the flow rate of the mixed gas is 0.2-0.4 m 3 / min, the introduction time is 20-40 min, and then the oxygen is stopped and the compressed air is continuously introduced at a flow rate of 0.2-0.3 m 3 / min; and obtaining silicon dioxide dust;

[0016] The liquid silicon is rolled under the blowing of the compressed air and the oxygen, the silicon particles with a size of less than 5 microns are separated from the liquid silicon under the action of heat and gas, and are floated upward, and are reacted with the oxygen during the floating process, and are affected by the surface tension to form spherical silicon dioxide.

[0017] Other impurities (such as calcium and aluminum) in the liquid silicon are oxidized at a high temperature of 1530-1600 ℃, and since the melting point of the oxidation products is higher than 2000 ℃, the oxides form solid slag in the liquid silicon, the oxygen is stopped after the slagging is completed, the amount of the compressed air is controlled at 0.2-0.3 m 3 / min, the amount of the oxygen is reduced, the oxidation reaction of the liquid silicon is weakened, and the slag gradually sinks to the bottom of the silicon ladle.

[0018] (3) dust collection, screening and iron removal: the silicon dioxide dust in step (2) is sucked into a dust collector through a draught fan, and then the powder collected in the dust collector is sent to a storage bin for temporary storage, and then is sent to a closed vibrating screen for screening, the screened powder is sent to an iron remover for iron removal, and the obtained coarse silicon dioxide powder is sent to a temporary storage bin for temporary storage;

[0019] (4) purification and separation: the coarse silicon dioxide powder in the temporary storage bin in step (3) is introduced into a chlorination furnace from the upper part of the chlorination furnace at a flow rate of 50-150 kg / h, hydrogen chloride gas is introduced into the chlorination furnace from the lower part of the chlorination furnace at a flow rate of 5-14 L / min, wherein the temperature in the chlorination furnace is 1030-1070 ℃, the coarse silicon dioxide powder stays in the chlorination furnace for 3-10 min, and then is discharged from the bottom of the chlorination furnace, so as to obtain silicon dioxide powder.

[0020] The alkali metal, alkaline earth metal and residual inclusion impurities of the spherical silica micro powder surface layer react with hydrogen chloride at high temperature to generate gaseous chlorides, and the high-temperature gas flow carries away the chlorides (mainly calcium chloride, iron chloride, aluminum chloride, sodium chloride, etc.) of these impurity elements, thereby achieving the purpose of deep purification.

[0021] Further, in step (2), the volume content of oxygen in the mixed gas is 30%-50%.

[0022] Further, in step (2), the pressure of the mixed gas is 0.4-0.8Mpa.

[0023] Further, in step (3), the oversize of the closed vibrating screen is sent to the impurity bin for storage.

[0024] Advantages of the present application:

[0025] 1. The present application provides a spherical silica preparation system, which has a simple connection structure, is easy to implement, and can mass-produce spherical silica micro powder. The spherical silica micro powder produced by the present application meets the quality requirements of ordinary spherical silica micro powder (QYG-R) in GB / T32661-2016, and the particle size of the produced spherical silica micro powder is 20-1000nm, meeting the use requirements of downstream customers.

[0026] 2. The present application provides a spherical silica preparation method, which uses silica, wood chips, coal, compressed air and oxygen as raw materials to synthesize high-value spherical silica micro powder. This method not only solves the problem of easy explosion of silica powder and the potential safety hazard, but also reduces the cost of raw materials.

[0027] 3. The present application provides a spherical silica preparation method, which uses a submerged arc furnace to continuously smelt at a temperature of 1500-1800℃. This method avoids the problem of ionizing radiation caused by electromagnetic wave heating, and also avoids the problem of high temperature requiring high-quality inner lining refractory materials in the reaction furnace. Moreover, the present application does not use hydrogen-containing fuel (i.e. methane), so the disclosed preparation method not only ensures the occupational health and safety of on-site workers, but also reduces the cost of equipment for producing silica; it is suitable for large-scale industrial production.

[0028] 4. The present application provides a spherical silica preparation method, which has a simple process and does not require treatment of the raw materials, thereby reducing the processing cost of raw materials. BRIEF DESCRIPTION OF DRAWINGS

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a process system diagram of the present invention.

[0031] Figure 2 This is a scanning electron microscope image of the spherical silica powder prepared in Example 2 of the present invention.

[0032] Figure 3 This is a scanning electron microscope image of the spherical silica powder prepared in Example 3 of the present invention.

[0033] Figure 4 This is a scanning electron microscope image of the spherical silica powder prepared in Example 4 of the present invention.

[0034] 1. Silicon water tank; 2. Oxygen delivery pipe; 3. Air compressor; 4. Fume hood; 5. Dust collector; 6. Exhaust fan; 7. Storage silo; 8. Enclosed vibrating screen; 9. Iron remover; 10. Temporary storage silo; 11. Chlorination furnace; 12. Hydrogen chloride gas delivery pipe; 13. Product storage silo; 14. Variable frequency rotary valve; 15. Miscellaneous waste silo. Detailed Implementation

[0035] The present invention will be further described in detail below through embodiments.

[0036] Example 1: As Figure 1 As shown, a system for preparing spherical silica includes: a silica water tank 1, an oxygen delivery pipe 2, an air compressor 3, a fume hood 4, a dust collector 5, an induced draft fan 6, a storage chamber 7, a closed vibrating screen 8, an iron remover 9, a temporary storage chamber 10, a chlorination furnace 11, and a hydrogen chloride gas delivery pipe 12; the outlets of the air compressor 3 and the oxygen delivery pipe 2 are both connected to the air inlet at the bottom of the silica water tank 1; a fume hood 4 is installed above the silica water tank 1, and the outlet of the fume hood 4 is connected to the air inlet of the dust collector 5. The outlet of the dust collector 5 is connected to the inlet of the induced draft fan 6 via a pipeline; the dust collector 5, storage bin 7, enclosed vibrating screen 8, iron remover 9 and temporary storage bin 10 are connected in sequence via pipelines; the outlet of the temporary storage bin 10 is connected to the inlet above the chlorination furnace 11 via a pipeline; the outlet of the hydrogen chloride gas conveying pipe 12 is connected to the inlet below the chlorination furnace 11 via a pipeline, and the outlet below the chlorination furnace 11 is connected to the inlet of the product storage bin 13 via a pipeline.

[0037] Variable frequency rotary valves 14 are installed at the discharge ports of storage bin 7 and temporary storage bin 10 respectively.

[0038] The discharge port of the enclosed vibrating screen 8 is connected to the feed port of the debris bin 15 through a pipe. The screen of the enclosed vibrating screen 8 is a 60-400 mesh screen.

[0039] This invention provides a system for preparing spherical silica, which can mass-produce spherical silica micro powder. The spherical silica micro powder produced by this invention meets the quality requirements of ordinary spherical silica micro powder (QYG-R) in GB / T32661-2016, and the particle size of the produced spherical silica micro powder is 20-1000nm, which meets the needs of downstream customers.

[0040] Example 2: A method for preparing spherical silica, comprising the following steps:

[0041] (1) Smelting: Silica, wood chips and coal are mixed in a mass ratio of 3:1.0:2.1 and then put into an electric arc furnace. The mixture is continuously smelted at a temperature of 1500-1800℃ to obtain liquid silicon.

[0042] (2) Oxygen blowing: The liquid silicon from step (1) is loaded into silicon water tank 1, and the temperature of the liquid silicon in silicon water tank 1 is 1530-1600℃; a mixture of compressed air and oxygen is introduced into the bottom of silicon water tank 1, and the flow rate of the mixture is 0.3m. 3 The oxygen flow rate was set at 0.25 m / min for 30 minutes, after which oxygen flow was stopped, and continued at a rate of 0.25 m / min. 3 Compressed air is introduced at a flow rate of / min; silica dust with a purity of 98.98% is obtained; the volume content of oxygen in the mixture is 40%, and the pressure of the mixture is 0.6 MPa.

[0043] (3) Dust collection, screening and iron removal: The silica dust in step (2) is drawn into the dust collector 5 by the blower 6. The powder collected in the dust collector 5 is then sent to the storage bin 7 for temporary storage, and then sent to the closed vibrating screen 8 for screening. The powder under the screen enters the iron remover 9 for iron removal. The coarse silica powder is then sent to the temporary storage bin 10 for temporary storage. The material on the screen of the closed vibrating screen 8 is sent to the miscellaneous material bin 15 for storage.

[0044] (4) Purification and separation: The crude silica powder in the temporary storage chamber 10 in step (3) enters from the top of the chlorination furnace 11 at a flow rate of 100 kg / h, and the hydrogen chloride gas enters from the bottom of the chlorination furnace 11 at a flow rate of 10 L / min. The temperature in the chlorination furnace 11 is 1030-1070℃. After the crude silica powder stays in the chlorination furnace 11 for 7 minutes, it is discharged from the bottom to obtain silica powder with a purity of 99.6%.

[0045] The spherical silica powder prepared in Example 2 of this invention was characterized; see [link to example]. Figure 2 ,Figure 2 The scanning electron microscope image of the spherical silica powder prepared in Example 2 of the present application is shown in Figure 2. Figure 2 As can be seen from Figure 2, the spherical nano-silica is prepared in the present application, wherein the particle size of the nano-silica is 20-600 nm.

[0046] Example 3: A method for preparing spherical silica, comprising the following steps:

[0047] (1) Smelting: mix silica, wood chips and coal in a mass ratio of 3:1.3:2.4 and then put them into a submerged arc furnace to perform continuous smelting at a temperature of 1500-1800℃, to obtain liquid silicon.

[0048] (2) Oxygen blowing: put the liquid silicon in step (1) into a silicon water tank 1, and the temperature of the liquid silicon in the silicon water tank 1 is 1530-1600℃; introduce a mixed gas of compressed air and oxygen into the bottom of the silicon water tank 1, the flow rate of the mixed gas is 0.4 m 3 / min, the introduction time is 20 min, and then stop introducing oxygen and continuously introduce compressed air at a flow rate of 0.3 m 3 / min; obtain silica dust with a purity of 99%; wherein the volume content of oxygen in the mixed gas is 50%, and the pressure of the mixed gas is 0.8 Mpa.

[0049] (3) Dust collection, screening and iron removal: the silica dust in step (2) is sucked into a dust collector 5 through a draught fan 6, and then the powder collected in the dust collector 5 is sent to a storage bin 7 for temporary storage, and then sent to a closed vibrating screen 8 for screening, the screened powder is sent to an iron remover 9 for iron removal, and the obtained coarse silica powder is sent to a temporary storage bin 10 for temporary storage; the oversize of the closed vibrating screen 8 is sent to a sundry bin 15 for storage.

[0050] (4) Purification and separation: the coarse silica powder in the temporary storage bin 10 in step (3) is introduced into a chlorination furnace 11 from the top at a flow rate of 150 kg / h, and hydrogen chloride gas is introduced into the chlorination furnace 11 from the bottom at a flow rate of 14 L / min, wherein the temperature in the chlorination furnace 11 is 1030-1070℃, and the coarse silica powder is discharged from the bottom of the chlorination furnace 11 after staying in the chlorination furnace 11 for 10 min, to obtain silica powder with a purity of 99.5%.

[0051] The spherical silica powder prepared in Example 3 of the present application is characterized; see Figure 3 , Figure 3 The scanning electron microscope image of the spherical silica powder prepared in Example 3 of the present application is shown in Figure 2. Figure 3 As can be seen from Figure 2, the spherical nano-silica is prepared in the present application, wherein the particle size of the nano-silica is 20-600 nm.

[0052] Embodiment 4: a preparation method of spherical silica, comprising the following steps:

[0053] (1) smelting: after mixing silica, wood chips and coal according to the mass ratio of 3:0.8:1.7, the mixture is put into an electric arc furnace, and continuous smelting is carried out at a temperature of 1500-1800℃, to obtain liquid silicon.

[0054] (2) oxygen blowing: the liquid silicon in step (1) is loaded into a silicon water tank 1, the temperature of the liquid silicon in the silicon water tank 1 is 1530-1600℃; compressed air and oxygen mixed gas are introduced into the bottom of the silicon water tank 1, the flow rate of the mixed gas is 0.2m 3 / min, the introduction time is 40min, then the oxygen introduction is stopped, and the compressed air is continuously introduced at a flow rate of 0.2m 3 / min; the obtained silica dust has a purity of 98.77%; wherein the volume content of oxygen in the mixed gas is 30%, and the pressure of the mixed gas is 0.4Mpa.

[0055] (3) dust collection and iron removal: the silica dust in step (2) is sucked into a dust collector 5 through a draught fan 6, then the powder collected in the dust collector 5 is sent to a storage bin 7 for temporary storage, and then sent to a closed vibrating screen 8 for screening, the screened powder is sent to an iron remover 9 for iron removal, and the obtained coarse silica powder is sent to a temporary storage bin 10 for temporary storage; the oversize of the closed vibrating screen 8 is sent to a sundry bin 15 for storage.

[0056] (4) purification and separation: the coarse silica powder in the temporary storage bin 10 in step (3) is introduced into a chlorination furnace 11 from the top at a flow rate of 50kg / h, hydrogen chloride gas is introduced into the chlorination furnace 11 from the bottom at a flow rate of 5L / min, wherein the temperature in the chlorination furnace 11 is 1030-1070℃, the coarse silica powder stays in the chlorination furnace 11 for 3min, and then is discharged from the bottom, to obtain silica powder with a purity of 99.9%.

[0057] The spherical silica powder prepared by the embodiment 4 of the present application is characterized; see Figure 4 , Figure 4 The scanning electron microscope image of the spherical silica powder prepared by the embodiment 4 of the present application is shown in the figure. Figure 4 As can be seen from the figure, the spherical nano-silica is prepared by the present application, wherein the particle size of the nano-silica is 20-1000nm.

[0058] The above is the preferred embodiment of the present application, and those skilled in the art can make some improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A system for the preparation of spherical silica comprising: The utility model relates to a kind of silicon water bags, oxygen delivery pipe and air compressor;The air compressor and the outlet of the oxygen delivery pipe are communicated with the gas inlet of the bottom of the silicon water bag;It further includes smoke hood, dust collector, induced draft fan, storage bin, closed vibrating screen, iron remover, temporary storage bin, chlorination furnace and hydrogen chloride gas delivery pipe;The smoke hood is arranged above the silicon water bag, and the outlet of the smoke hood is communicated with the gas inlet of the dust collector by pipeline, and the outlet of the dust collector is communicated with the gas inlet of the induced draft fan by pipeline;The dust collector, the storage bin, the closed vibrating screen, the iron remover and the temporary storage bin are sequentially communicated by pipeline;The discharge outlet of the temporary storage bin is communicated with the feed inlet above the chlorination furnace by pipeline;The outlet of the hydrogen chloride gas delivery pipe is communicated with the gas inlet below the chlorination furnace by pipeline; The preparation method comprises the following steps: (1) smelting: after mixing silica, wood chips and coal according to a mass ratio of 3:0.8-1.3:1.7-2.4, the mixture is put into a submerged arc furnace, and continuous smelting is carried out at a temperature of 1500-1800 ℃ to obtain liquid silicon; (2) Oxygen blowing: the liquid silicon in step (1) is charged into a silicon ladle, the temperature of the liquid silicon in the silicon ladle is 1530-1600℃; a mixed gas of compressed air and oxygen is introduced into the bottom of the silicon ladle, the flow rate of the mixed gas is 0.2-0.4m 3 / min, the introduction time is 20-40min, then the oxygen introduction is stopped, and the compressed air is continuously introduced at a flow rate of 0.2-0.3m 3 / min; silica fume is obtained; (3) dust collection, screening and iron removal: the silica dust in step (2) is sucked into a dust collector by an induced draft fan, and then the powder collected in the dust collector is temporarily stored in a storage bin and then screened in a closed vibrating screen, the undersize powder is subjected to iron removal in an iron remover, and the obtained coarse silica powder is temporarily stored in a temporary storage bin; (4) purification and separation: the coarse silica powder in the temporary storage bin in step (3) is fed into the chlorination furnace from the top at a flow rate of 50-150 kg / h, hydrogen chloride gas is fed into the chlorination furnace from the bottom at a flow rate of 5-14 L / min, the temperature in the chlorination furnace is 1030-1070 ℃, the coarse silica powder stays in the chlorination furnace for 3-10 min and is discharged from the bottom to obtain silica powder.

2. The system for preparing spherical silica according to claim 1, wherein The discharge outlet below the chlorination furnace is communicated with the feed inlet of a product storage bin by pipeline.

3. The system for preparing spherical silica according to claim 1, wherein A variable-frequency star-type unloader is arranged on the discharge outlet of the storage bin and the temporary storage bin, respectively.

4. The system for preparing spherical silica according to claim 1, wherein The impurity inlet of the closed vibrating screen is communicated with the feed inlet of an impurity bin by pipeline.

5. The system for preparing spherical silica according to claim 4, wherein The screen mesh of the closed vibrating screen is a 60-400 mesh screen.

6. The system for preparing spherical silica according to claim 1, wherein In step (2), the volume content of oxygen in the mixed gas is 30%-50%.

7. The system for preparing spherical silica according to claim 1, wherein In step (2), the pressure of the mixed gas is 0.4-0.8 MPa.

8. The system for preparing spherical silica according to claim 1, wherein In step (3), the oversize material of the closed vibrating screen is sent to the impurity bin for storage.

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