Gel curing forming equipment and preparation device and preparation method of high-purity sandy silicon dioxide

Abstract

The invention discloses gel curing forming equipment and a preparation device and method of high-purity sandy silicon dioxide, and belongs to the technical field of chemical production. The preparation method provided by the invention solves the problems that the gel particles are easy to crack and flake, secondary crushing and purification are needed after drying or roasting, the transparency is poor and the like in the existing traditional process mode. Gel particles which are free of cracks and good in circularity are obtained through designed gel curing forming equipment in combination with a technological gelation method and an integrated drying mode, and then the high-purity sandy silicon dioxide which is low in hydroxyl, high in purity and suitable in particle size and has closed pores is obtained through a sintering mode, so that the method is rapid, effective, high in universality and suitable for large-scale production. The preparation method can be well applied to industrial large-scale production of the high-purity silicon dioxide material.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical production, and particularly relates to a gel curing and forming device, a preparation device and a preparation method of high-purity sand-like silica. Background Art

[0002] Conventional sand-like silica is mainly sourced from natural ore raw materials, which are obtained by electrofusion followed by crushing. There is also a method using silicon tetrachloride (SiCl4) as the raw material, hydrolyzing in a hydrogen-oxygen flame, electrofusing, and then crushing. Obviously, neither of these belongs to a clean energy method. Moreover, in terms of purity, the limit of the natural ore purification process is between 5N and 6N, and it is difficult to achieve higher purity. While the liquid-phase synthesis method using organosilicate, chlorosilane, etc. can increase the purity to 7N or even higher, up to 9N. In comparison, the liquid-phase synthesis process has a low reaction temperature, simple equipment, less energy consumption, and higher product purity, showing strong industrial application prospects.

[0003] As the liquid-phase synthesis method mainly uses the sol-gel method, it can be an inorganic method. For example, using water glass, silicon tetrachloride, chlorosilane, etc. as raw materials, forming a sol through hydrolysis and adjusting the system. It can also be an organic method. For example, using alkoxysilanes such as tetramethoxysilane and tetraethoxysilane, as well as their oligomers, etc. as raw materials, in a dispersant such as alcohol, and adding an alkali or acid catalyst, forming a sol through hydrolysis. Whether it is an organic method or an inorganic method, after obtaining the sol, it is necessary to go through processes such as drying and calcination, and then further crush it into sand-like silica.

[0004] Therefore, in the existing production and application of synthetic sand-like silica, processes such as drying, calcination, and crushing are considered technical bottlenecks. For example, drying is prone to cracking, there is a lot of flying dust during crushing, high energy consumption, and easy pollution. Especially in the drying process, in most synthetic sol processes, alcohols, aromatics, organic amines, etc. are used as hydrolysis agents or modified solvents for monomers. Coupled with a large number of network (cage) crosslinkings after gelation, these solvents are easily trapped in them, making it difficult for ordinary drying equipment to remove them completely in a short time. Coupled with the huge capillary force generated during the removal of strongly polar moisture, the obtained gel particles generally have cracking phenomena and are difficult to form. Even in the subsequent calcination process, even if it is carried out slowly for a long time, even dozens of hours, microbubbles can still be seen inside the obtained sand-like silica, and the transparency is relatively low.

[0005] Even worse, after drying or calcination, further crushing is required. At this time, because the particles have been densified and have a certain hardness, fine particles are extremely easy to generate during the operation process, the yield is low, and it is extremely easy to be polluted. Summary of the Invention

[0006] In view of the deficiencies of the prior art and the problems existing in the equipment, the present invention discloses a gel curing and forming equipment, a preparation device and a preparation method for high-purity sand-like silica. The present invention uses conventional silicon sources, ultrapure water, organic solvents, etc. as raw materials, adds silicon powder with appropriate particle size, adjusts the formula with additives, and adopts a uniquely designed gel curing and forming equipment to directionally control the formation of gel particles within a certain particle size range, and then obtains high-purity sand-like silica with closed pores, low hydroxyl groups, high purity, no cracking, good roundness and suitable particle size through a sintering method.

[0007] To achieve the above object, the technical solutions adopted by the present invention are as follows: The present invention provides a gel curing and forming equipment, which includes a cylindrical jacketed housing 1. The top of the cylindrical jacketed housing 1 is provided with a hollow cover 2. One side of the hollow cover 2 connected to the cylindrical jacketed housing 1 is provided with micropores 14. The inside of the hollow cover 2 is filled with an adsorbent 13. One side wall of the cylindrical jacketed housing 1 close to the micropores 14 is provided with a discharge port 15. The bottom of the cylindrical jacketed housing 1 is an inverted cone. The side wall of the inverted cone is provided with a first carrier gas port 4. The inside of the inverted cone is provided with a piston-type sieve cutter 9. The piston-type sieve cutter 9 can slowly move along the inner wall of the cylindrical jacketed housing 1 to cut the gel 3 into microparticles. The bottom of the inverted cone has an opening. The piston-type sieve cutter 9 passes through the opening and communicates with a collector 17. A sealing ring 12 is provided at the opening.

[0008] Optionally, the piston-type sieve cutter 9 is a funnel-shaped structure, with a screen 6 at the top and a hollow tube 5 connected at the bottom. The bottom of the hollow tube 5 is provided with a quick interface 11. One side wall of the hollow tube 5 close to the quick interface 11 is provided with a second carrier gas port 18.

[0009] Optionally, the side wall of the screen 6 is provided with a groove, and an O-ring 7 is provided in the groove.

[0010] Optionally, the top of the hollow cover 2 is provided with a filling port 16.

[0011] Optionally, the jacket inside the cylindrical jacketed housing 1 is filled with a heat medium.

[0012] Optionally, the adsorbent 13 is selected from at least one of 4A molecular sieve, 3A molecular sieve, 2A molecular sieve, 13X molecular sieve, LiX molecular sieve, water-absorbing silica gel, calcium chloride and sodium sulfate.

[0013] Optionally, the aperture size of the screen 6 is 5-15 mm.

[0014] Optionally, the pore size of the microchannel 14 is 1 to 3 mm.

[0015] Optionally, the distance between the discharge port 15 and the microchannel 14 is 5 to 10 mm.

[0016] Optionally, the distance between the second carrier gas port 18 and the quick interface 11 is 25 to 100 mm.

[0017] The present invention also provides a device for preparing high-purity sand-like silica, and the device includes the above-mentioned gel curing and forming equipment.

[0018] The present invention also provides a method for preparing high-purity sand-like silica, and the preparation method includes pulping, shaping, and roasting. The shaping is carried out using the above-mentioned gel curing and forming equipment.

[0019] Optionally, the pulping includes mixing and stirring silicon powder, a silicon source, water, and an auxiliary agent to obtain a slurry; the shaping includes heating the slurry to form a gelified solid and cutting the obtained gelified solid into microparticles; the roasting includes roasting the microparticles.

[0020] Optionally, the viscosity range of the slurry is 20 to 300 mPa·s.

[0021] Optionally, the heating temperature for forming the gelified solid is 20 to 95 °C, and the heating time is 0.5 h to 48 h.

[0022] Optionally, in the gel curing and forming equipment, the pressure during the use of the first carrier gas port is 0.4 to 1.2 Mpa, the flow rate is 2.5 to 5 L / min, the pressure during the use of the second carrier gas port is 0.05 to 0.4 Mpa, and the flow rate is 0.25 to 2 L / min.

[0023] Optionally, the temperature of the roasting treatment is 1000 to 1200 °C, and the time is 15 to 30 h.

[0024] Optionally, the silicon source is selected from inorganic silica sol or organic silica sol. The inorganic silica sol includes a sol formed by using water glass, silicon tetrachloride, or chlorosilane as a raw material through hydrolysis and adjusting the system. The organic silica sol includes a sol formed by using alkoxysilane and / or an oligomer of alkoxysilane as a raw material and adding an alkali or acid catalyst for hydrolysis under a dispersant.

[0025] Optionally, the particle size of the silicon powder is 0.3 to 10 μm.

[0026] Optionally, the auxiliary agent is an acidic substance or a basic substance, including hydrochloric acid, acetic acid, maleic acid, lactic acid, citric acid, ammonia water, amine-based organic bases, etc.

[0027] Optionally, the molar ratio of the silicon source, water and the auxiliary agent is 1:5 to 50:0.0005 to 0.05, and the addition amount of the silicon powder is 0.005% to 0.5% of the total mass of the silicon source, water and the auxiliary agent.

[0028] Optionally, the preparation method includes the following steps: Step 1: Prepare a slurry of a silicon source, silicon powder and an auxiliary agent in a vacuum stirrer. Step 2: Fix the piston-type sieve cutter to the collector, supplement the piston-type sieve cutter with the second carrier gas port for resetting, inject the slurry obtained in Step 1 into the inner cavity of the gel curing and forming device, and seal it with a hollow cover equipped with an adsorbent. Step 3: Heat the slurry to form a gelled solid. The evaporated solvent passes through the microchannels, and the water therein is selectively absorbed by the adsorbent. Step 4: First, open the discharge port, then open the second carrier gas port. After 0.2 to 1 hour, close the discharge port and the second carrier gas port simultaneously, and then open the first carrier gas port to push the piston-type sieve cutter to cut the gelled solid into micro-particles in an approximate spherical shape with a size of 100 to 1000 mm, which are collected by the collector. Step 5: Load the micro-particles into a quartz crucible and send them into a roasting furnace for roasting to obtain high-purity sand-like silicon dioxide.

[0029] In Step 2 of the present invention, when the slurry is injected into the gel curing and forming device, since the slurry has a certain viscosity, a film will be formed on the surface of the sieve mesh of the piston-type sieve cutter, so it will not pass through the sieve mesh.

[0030] In Step 2 of the present invention, the adsorbent in the hollow cover has been subjected to roasting and dehydration treatment in advance.

[0031] In Step 3 of the present invention, at a constant temperature, the slurry is heated to form an approximate jelly-like gelled solid. In this process, the hot solvent in the system evaporates and passes through the microchannels, and only the water vapor is selectively removed by the adsorbent, and the resulting air pressure deviation draws more water to be removed.

[0032] The present invention also provides a high-purity sand-like silicon dioxide prepared by the above preparation method, and the roundness of the high-purity sand-like silicon dioxide is 0.8 to 1, and the hydroxyl number is 15 to 100 ppm.

[0033] The beneficial effects of the present invention include: The preparation method of the present invention solves the problems in the existing traditional process methods, such as easy cracking and powdering of gel particles, and the need for secondary crushing, purification, and poor transparency after drying or roasting. Through the designed gel curing and forming equipment, combined with the process gelation method and integrated drying method, gel particles without cracking and with good roundness are obtained. Then, through the sintering method, high-purity dense sand-like silica with closed pores, low hydroxyl groups, high purity, and suitable particle size is obtained. It is a fast and effective preparation method with high versatility and can be well applied to the industrial scale production of high-purity silica materials. Brief Description of the Drawings

[0034] Figure 1 It is a structural diagram of the gel curing and forming equipment of the present invention.

[0035] Figure 2 It is a structural diagram of the piston-type sieve knife of the present invention.

[0036] Figure 3 It is a process flow diagram of the preparation method of high-purity sand-like silica of the present invention.

[0037] In the figure, 1 is a cylindrical jacketed housing; 2 is a hollow cover; 3 is a gel; 4 is a first carrier gas port; 5 is a hollow tube; 6 is a sieve mesh; 7 is an O-ring; 8 is an inner cavity; 9 is a piston-type sieve knife; 10 is a hand-tightening bolt; 11 is a quick interface; 12 is a sealing ring; 13 is an adsorbent; 14 is a micropore channel; 15 is a discharge port; 16 is a filling port; 17 is a collector; 18 is a second carrier gas port. Detailed Embodiments

[0038] The following is further described in conjunction with the drawings and embodiments, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making the protection scope of the present invention more clearly defined.

[0039] As Figure 1 shown, a gel curing and forming equipment includes a cylindrical jacketed housing 1. The top of the cylindrical jacketed housing 1 is hermetically connected with a hollow cover 2 through a hand-tightening bolt 10. The side of the hollow cover 2 connected to the cylindrical jacketed housing 1 is provided with a protruding micropore channel 14 with a pore size of 1-3 mm. When the hand-tightening bolt 10 is tightened, the protruding micropore channel 14 is inserted into the inside of the cylindrical jacketed housing 1, and the insertion depth is 5-10 mm.

[0040] The inside of the hollow cover 2 is filled with an adsorbent 13, and the adsorbent 13 is selected from at least one of 4A molecular sieve, 3A molecular sieve, 2A molecular sieve, 13X molecular sieve, LiX molecular sieve, water-absorbing silica gel, calcium chloride, and sodium sulfate.

[0041] When selecting the adsorbent for the present invention, the diameter of the solvent molecules is preferentially considered to selectively remove moisture.

[0042] A filling port 16 is provided at the top of the hollow cover 2 for filling the adsorbent 13.

[0043] A discharge port 15 is provided on one side wall of the cylindrical jacketed housing 1 close to the microchannel 14, and the distance between the discharge port 15 and the microchannel 14 is 5 - 10 mm.

[0044] The bottom of the cylindrical jacketed housing 1 is an inverted cone, a first carrier gas port 4 is provided on the side wall of the inverted cone, a piston - type sieve knife 9 is provided inside the inverted cone, and the piston - type sieve knife 9 can slowly move along the inner wall of the cylindrical jacketed housing 1 to cut the gel 3 into microparticles.

[0045] The bottom of the inverted cone has an opening, the piston - type sieve knife 9 passes through the opening and communicates with the collector 17, and a sealing ring 12 is provided at the opening to ensure the seal inside the inverted cone.

[0046] In the present invention, by inputting carrier gas into the first carrier gas port 4, the piston - type sieve knife 9 is pushed to slowly move along the inner wall of the cylindrical jacketed housing 1, and the moving range includes the entire inner cavity of the cylindrical jacketed housing 1. In this process, the gel 3 can be cut into approximately spherical microparticles and collected by the collector 17.

[0047] The conical surface of the piston - type sieve knife 9 fits the bottom conical surface of the cylindrical jacketed housing 1, and the whole can be made of resin materials such as polyvinyl chloride, polypropylene, polyether ether ketone, etc.

[0048] The inside of the jacket of the cylindrical jacketed housing 1 is filled with a heat medium to heat the slurry to form a gel - like solid; the inner lining of the cylindrical jacketed housing 1 can be made of polytetrafluoroethylene.

[0049] As Figure 2 shown, the piston - type sieve knife 9 is a funnel - shaped structure, a sieve mesh 6 with a pore size of 5 - 15 mm is provided at the top, a hollow tube 5 is connected to the bottom, and a quick - connection interface 11 is provided at the bottom of the hollow tube 5 for connecting to the collector 17.

[0050] A second carrier gas port 18 is provided on one side wall of the hollow tube 5 close to the quick - connection interface 11 for purging air flow to reset the piston - type sieve knife 9, and the distance between the second carrier gas port 18 and the quick - connection interface 11 is 25 - 100 mm.

[0051] Grooves are provided on the side wall of the sieve mesh 6, and O - rings 7 are provided in the grooves to ensure the sealed sliding of the piston - type sieve knife 9 on the inner wall of the cylindrical jacketed housing 1.

[0052] The present invention is provided with a plurality of valves for controlling the opening and closing of the discharge port 15, the first carrier gas port 4, and the second carrier gas port 18.

[0053] The evaluation method of the present invention: Residual carbon (ppm): After calcining the formed gel particles at 300 ± 5 °C for 10 h, they are detected and analyzed on a LECO carbon and sulfur analyzer in the United States.

[0054] Specific surface area: The nitrogen adsorption amount of the formed gel particles is measured on a Micromeritics ASAP physical adsorption instrument in the United States.

[0055] Hydroxyl number (ppm): The calcined sand-like silica is detected by FTIR, and the infrared absorption intensity at about 3600 cm -1 is converted by the Lambert-Beer law.

[0056] Circularity: Using a CAMSIZER 3D dynamic image analyzer, the circularity is calculated using the formula circularity = 4πS / L 2 . Where S is the projected area of the particle and L is the projected perimeter of the particle.

[0057] Example 1 A gel curing and forming device includes a cylindrical jacketed housing 1. The top of the cylindrical jacketed housing 1 is hermetically connected with a hollow cover 2 through a hand-tightening bolt 10. One side of the hollow cover 2 connected to the cylindrical jacketed housing 1 is provided with a protruding microchannel 14 with a pore size of 2 mm. When the hand-tightening bolt 10 is tightened, the protruding microchannel 14 is inserted into the interior of the cylindrical jacketed housing 1 with an insertion depth of 8 mm.

[0058] The top of the hollow cover 2 is provided with a filling port 16, and an adsorbent 13 is filled inside. The adsorbent 13 is 3A molecular sieve.

[0059] On one side wall of the cylindrical jacketed housing 1 close to the microchannel 14, a discharge port 15 is provided, and the distance between the discharge port 15 and the microchannel 14 is 5 mm.

[0060] The bottom of the cylindrical jacketed housing 1 is an inverted cone. A first carrier gas port 4 is provided on the side wall of the inverted cone, and a piston-type sieve cutter 9 is provided inside. The piston-type sieve cutter 9 can slowly move along the inner wall of the cylindrical jacketed housing 1 to cut the gel 3 into micro-particles.

[0061] The bottom of the inverted cone has an opening. The piston-type sieve cutter 9 passes through the opening and communicates with the collector 17, and a sealing ring 12 is provided at the opening.

[0062] The conical surface of the piston-type sieve cutter 9 fits with the bottom conical surface of the cylindrical jacketed housing 1, and the whole is made of polyvinyl chloride.

[0063] The inner lining of the cylindrical jacketed shell 1 is made of polytetrafluoroethylene, and its jacket is filled with a heat medium.

[0064] The piston-type sieve knife 9 is in a funnel shape, with a sieve mesh 6 with a pore size of 5 mm at the top, and a hollow tube 5 is connected to the bottom. A quick connector 11 is provided at the bottom of the hollow tube 5 for connecting to the collector 17.

[0065] A second carrier gas port 18 is provided on one side wall of the hollow tube 5 near the quick connector 11, and the distance between the second carrier gas port 18 and the quick connector 11 is 10 mm.

[0066] A groove is provided on the side wall of the sieve mesh 6, and an O-ring 7 is provided in the groove. Example 2

[0067] Silica powder preparation: natural fused quartz powder, purity > 99.94%, particle size 20 - 50 µm; yttrium-stabilized zirconia balls: Ф3 mm; wet grinding dispersion medium: ultrapure water; mixing and grinding are carried out in a weight ratio of natural fused quartz powder to ultrapure water of 1:2, rotation speed 400 r / min, and duration 8 h; The obtained silica powder is washed 3 times with a 5 wt% electronic-grade hydrochloric acid solution, and then washed 3 times with ultrapure water, and dried to obtain high-purity silica powder with a particle size of 0.6 - 5 µm (purity > 99.99%).

[0068] Pulping: purified tetraethyl orthosilicate, ultrapure water, the above-mentioned silica powder, and the additive is electronic-grade lactic acid are stirred in a vacuum stirrer for 1.5 h to prepare a viscous slurry with a viscosity of 90 mPa·s; among them, the molar ratio of tetraethyl orthosilicate, ultrapure water, and electronic-grade lactic acid is 1:15:0.018, and the mass ratio of silica powder added is 0.055%.

[0069] Shaping: Fix the collector on the piston-type sieve knife in Example 1, and supplement it with a second carrier gas port pressure of 0.25 Mpa and a flow rate of 1.2 L / min. Reset the piston-type sieve knife, and inject the above slurry into the inner cavity of the cylindrical jacketed shell. Because the slurry has a certain viscosity, it will form a film on the surface of the sieve mesh of the piston-type sieve knife. Use a hollow cover plate filled with 3A molecular sieve to seal the cylindrical jacketed shell. The 3A molecular sieve in the hollow cover plate has been pre-dehydrated by calcination at 400 °C for 6 h.

[0070] Inject 90 °C hot water into the jacket of the cylindrical jacketed shell to make the slurry react to form a gel, heat for 20 h, and age the gel to enhance the degree of gelation, finally forming an approximately jelly-like gelified solid. In this process, the hot solvent in the system evaporates and passes through the microchannels, and only water vapor is selectively removed by the adsorbent, and the resulting air pressure deviation draws more water to be removed.

[0071] The above process continues for 36 h, then the constant-temperature heating is stopped, the discharge port is opened, and the second carrier gas is supplemented with a pressure of 0.1 Mpa and a flow rate of 0.25 L / min. After 12 h, the discharge port and the second carrier gas port are closed. Then, the first carrier gas port is supplemented with a pressure of 0.5 Mpa and a gas flow rate of 2.5 L / min to push the piston-type sieve cutter to cut the gelled solid into approximately spherical particles with a size of 100 - 1000 mm, which are collected by the collector. The obtained gel particles have no cracks, the residual carbon is measured to be 312 ppm, the specific surface area is measured to be 553 m 2 / g, and the pore volume is 1.1 cm 3 / g, and the pore diameter is 11.13 nm.

[0072] Roasting: Subsequently, the above gel particles are loaded into a quartz crucible and sent to a roasting furnace for roasting, that is, calcined at 300 °C for 5 h, 500 °C for 5 h, 700 °C for 5 h, 900 °C for 10 h, and 1200 °C for 30 h. After that, 5N (99.999%) high-purity sand-like silica is obtained, with a hydroxyl number of 27 ppm and a roundness of 0.85. Example 3

[0073] The same synthesis process as in Example 2 is carried out, with the specific differences as follows: the molar ratio of purified methyl silicate, ultrapure water, and electronic-grade hydrochloric acid is 1:16:0.025, and the addition amount of silicon powder is 0.025%. Among them, the silicon powder is prepared by the following process: 3 kg of commercially available water glass with a solid content of 29.48% and a viscosity of 176 mPa·s is slowly dropped into 1 L of 16.3 wt% sulfuric acid solution, 35 g of 50.2 wt% hydrogen peroxide is added, and stirred for 15 min. Then, the temperature is raised to 50 °C, stirred for 30 min to precipitate, and the precipitate is washed twice with 1 L of ultrapure water and filtered. Then, the filtrate is put into 0.5 L of 24.5% sulfuric acid aqueous solution, 1.5 g of citric acid, 20.8 g of 50.3% hydrogen peroxide are added, and stirred evenly for 10 min. The temperature is raised to 70 °C, stirred for 1 h, filtered, then washed twice with ultrapure water, dried at 125 °C for 24 h, and roasted at 1050 °C for 5 hours to obtain silicon powder.

[0074] Through the gel solidification and forming equipment of Example 1, the obtained gel particles have no cracks, the residual carbon is measured to be 276 ppm, the specific surface area is measured to be 447 m 2 / g, and the pore volume is 0.91 cm 3 / g, and the pore diameter is 10.09 nm.

[0075] Subsequently, the above gel particles are loaded into a quartz crucible and sent to a roasting furnace for roasting. Under the same roasting conditions, 4N8 (99.998%) high-purity sand-like silica is obtained, with a hydroxyl number of 35 ppm and a roundness of 0.83. Comparative Example 1

[0076] According to Example 2, with the same pulping process, on ordinary gelation equipment, the same isothermal process is carried out, but no dehydration treatment is performed. After gel solidification, cracks begin to appear on the surface, and the gel is broken into 0.5 - 15 mm gel particles by a pair of rollers. The particle fullness is low, the roundness is poor, there are more fines, and the yield is on the low side. The residual carbon is measured to be 725 ppm, the specific surface area is measured to be 531 m 2 / g, and the pore volume is 1.0 cm 3 / g, and the pore diameter is 10.11 nm.

[0077] Subsequently, the above-mentioned gel particles are loaded into a quartz crucible and sent to a roasting furnace for roasting. Under the same roasting conditions, 4N8 (99.998%) high-purity sand-like silica is obtained, with a hydroxyl number of 75 ppm and a roundness of 0.63. Comparative Example 2

[0078] According to Example 3, with the same pulping process, on ordinary gelation equipment, the same isothermal process is carried out, but no dehydration treatment is performed. After gel solidification, cracks begin to appear on the surface, and the gel is broken into 0.5 - 10 mm gel particles by a pair of rollers. The particle fullness is low, the roundness is poor, there are more fines, and the yield is on the low side. The residual carbon is measured to be 872 ppm, the specific surface area is measured to be 432 m 2 / g, and the pore volume is 0.98 cm 3 / g, and the pore diameter is 0.93 nm.

[0079] Subsequently, the above-mentioned gel particles are loaded into a quartz crucible and sent to a roasting furnace for roasting. Under the same roasting conditions, 4N5 (99.995%) high-purity sand-like silica is obtained, with a hydroxyl number of 68 ppm and a roundness of 0.70.

[0080] The above are only the embodiments of the present invention, and thus do not limit the patent scope of the present invention. Any equivalent structural or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be similarly included in the patent protection scope of the present invention.

Claims

1. A gel curing molding device, characterized in that: The device comprises a cylindrical jacket shell (1), a hollow cover (2) is provided on the top of the cylindrical jacket shell (1), a microchannel (14) is provided on a side of the hollow cover (2) connected to the cylindrical jacket shell (1), and an adsorbent (13) is filled inside the hollow cover (2). A discharge port (15) is provided on a side wall of the cylindrical jacket shell (1) close to the microchannel (14). The bottom of the cylindrical jacket shell (1) is an inverted cone, a first carrier gas port (4) is provided on the side wall of the inverted cone, a piston-type screen cutter (9) is provided inside the inverted cone, and the piston-type screen cutter (9) can move slowly along the inner wall of the cylindrical jacket shell (1), thereby cutting the gel (3) into microparticles. The bottom of the inverted cone has an opening, and the piston-type screen cutter (9) passes through the opening to communicate with the collector (17), and a sealing ring (12) is provided at the opening.

2. The device according to claim 1, characterized in that The piston-type screen cutter (9) is a funnel-shaped structure, with a screen (6) provided on the top and a hollow tube (5) connected to the bottom. A quick interface (11) is provided at the bottom of the hollow tube (5), and a second carrier gas port (18) is provided on a side wall of the hollow tube (5) close to the quick interface (11).

3. The device according to claim 1 or 2, characterized in that A groove is provided on the side wall of the screen (6), and an O-ring (7) is provided in the groove; And / or, the top of the hollow cover (2) is provided with a filling port (16); And / or, the interior of the jacket of the cylindrical jacket housing (1) is filled with a heat medium; And / or, the adsorbent (13) is at least one selected from 4A molecular sieve, 3A molecular sieve, 2A molecular sieve, 13X molecular sieve, LiX molecular sieve, water-absorbent silica gel, calcium chloride and sodium sulfate.

4. The device according to any one of claims 1 to 3, characterized in that: The pore size of the sieve (6) is 5-15 mm; And / or, the pore size of the microchannel (14) is 1-3 mm; and / or, the distance between the discharge port (15) and the microchannel (14) is 5 to 10 mm; And / or, the distance between the second carrier gas port (18) and the quick interface (11) is 25-100 mm.

5. A device for preparing high-purity sand-like silicon dioxide, characterized in that: The device comprises the gel curing molding equipment according to any one of claims 1 to 4.

6. A method for preparing high-purity sand-like silicon dioxide, characterized in that: The preparation method comprises pulping, shaping and roasting, wherein the shaping is performed by using the equipment described in any one of claims 1 to 4.

7. The preparation method according to claim 6, characterized in that: The slurrying comprises mixing and stirring silicon powder, silicon source, water and additives to obtain slurry; the shaping comprises heating the slurry to form a gelled solid, and cutting the obtained gelled solid into microparticles; the calcining comprises calcining the microparticles; and / or, the viscosity of the slurry is in the range of 20 to 300 mPa·s; And / or, the heating temperature for forming a gelled solid is 20-95° C., and the heating time is 0.5 h-48 h; And / or, in the gel curing molding equipment, the pressure during use of the first carrier gas port is 0.4~1.2Mpa, the flow rate is 2.5~5L / min, and the pressure during use of the second carrier gas port is 0.05~0.4Mpa, the flow rate is 0.25~2L / min; And / or, the calcination treatment is carried out at a temperature of 1000-1200° C. and for a time of 15-30 hours.

8. The preparation method according to claim 6 or 7, characterized in that: The silicon source is selected from inorganic silica sol or organic silica sol. The inorganic silica sol includes a sol formed by hydrolysis of water glass, silicon tetrachloride or chlorosilane as raw materials, and the organic silica sol includes a sol formed by hydrolysis of alkoxysilane and / or alkoxysilane oligomers as raw materials in the presence of a dispersant by adding a base or an acid; And / or, the silicon powder has a particle size of 0.3-10 μm; and / or, the auxiliary agent is selected from any one of hydrochloric acid, acetic acid, maleic acid, lactic acid, citric acid, ammonia water or an amine organic base; And / or, the molar ratio of the silicon source, water and auxiliary agent is 1:5~50:0.0005~0.05, and the added amount of the silicon powder is 0.005%~0.5% of the total mass of the silicon source, water and auxiliary agent.

9. The preparation method according to any one of claims 6 to 8, characterized in that The following steps are included: Step 1: In a vacuum agitator, a silicon source, silicon powder and an additive are prepared into a slurry; Step 2: The piston-type screen cutter is fixedly connected to the collector, and the piston-type screen cutter is reset with the aid of a second carrier gas port, and the slurry described in step 1 is injected into the inner cavity of the gel curing molding device, and sealed with a hollow cover filled with an adsorbent; Step 3, heating the slurry to form a gelled solid, the evaporated solvent passes through the micro-channels, and the water therein is selectively absorbed by the adsorbent; Step 4: first open the discharge port, then open the second carrier gas port, and continue for 0.2 to 1 hour, then close the discharge port and the second carrier gas port at the same time, and then open the first carrier gas port, push the piston-type screen cutter to cut the gelled solid into 100 to 1000 mm approximately spherical microparticles, which are collected by the collector; Step 5: The microparticles are loaded into a quartz crucible and sent into a calcining furnace for calcining to obtain high-purity sand-like silicon dioxide.

10. A high-purity sand-like silicon dioxide obtained by the preparation method according to any one of claims 6 to 9, characterized in that: The high-purity sand-like silica has a circularity of 0.8-1 and a hydroxyl number of 15-100 ppm.

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