Integrated equipment and method for synthesizing high-purity quartz sand

Abstract

The invention discloses integrated equipment and a method for synthesizing high-purity quartz sand, and belongs to the technical field of quartz sand production. Through the integrated design of the integrated equipment, continuous operation of key procedures such as material liquid phase reaction, sol preparation, directional forming and cleaning is realized, the pollution hidden danger caused by switching of multiple equipment is effectively avoided, and high purity and high quality of the product are ensured. According to the integrated equipment, an airflow auxiliary system is utilized, the thermocuring and directional forming process is precisely regulated and controlled, organic component residues are thoroughly removed, and finally the high-purity synthetic quartz sand which is closed in air hole, low in hydroxyl group, high in purity and free of black spots is prepared through a sintering technology. The preparation method is efficient and rapid, is especially suitable for industrial large-scale production of artificially synthesized high-purity quartz sand, and provides an advanced and reliable brand-new solution with remarkable economic benefits for related industries.

Description

Technical Field

[0001] This invention belongs to the field of quartz sand production technology, specifically relating to an integrated equipment and method for synthesizing high-purity quartz sand. Background Technology

[0002] Traditional methods for preparing quartz sand primarily rely on natural ore resources, involving electrofusion followed by crushing. Alternatively, silicon tetrachloride (SiCl4) can be used as a raw material, undergoing hydrolysis in an oxyhydrogen flame followed by electrofusion and crushing. However, these traditional methods have limitations in energy utilization and cannot be considered clean and efficient. More importantly, the purification processes for natural ore are nearing their technological limits, typically achieving only 5N (99.999%) purity, with further improvements facing significant technical challenges. In contrast, liquid-phase synthesis methods using organosilicon alkoxides and chlorosilanes offer substantial advantages. These processes require lower reaction temperatures, simpler equipment, and significantly reduced energy consumption. More importantly, it can increase the purity of quartz sand to 7N (99.99999%) or even higher levels like 11N (99.999999999%), greatly satisfying the stringent purity requirements of high-end electronic semiconductor fields. In summary, the synthesis process, with its superior performance in terms of energy consumption, equipment requirements, and product purity, demonstrates strong industrial application potential and is expected to become an important development direction in the future of quartz sand preparation.

[0003] However, in the existing complete production application of synthetic silica sand, its preparation process is complex and cumbersome, requiring the use of multiple processing equipment in tandem. This not only leads to low work efficiency but also significantly increases preparation costs and energy consumption. Furthermore, the switching between multiple pieces of equipment increases the likelihood of contamination, making it difficult to guarantee purity.

[0004] In addition, in most synthetic sol processes, when silanol salts are hydrolyzed, alcohols are generated. These alcohols are easily trapped during sol gelation, making it difficult for ordinary drying equipment to remove them completely in a short time. Furthermore, the huge capillary force generated during the removal of highly polar water causes the resulting gel particles to crack and become difficult to shape. Even with a long and slow calcination process, sometimes lasting tens of hours, the resulting synthetic quartz sand still shows visible microbubbles, black coatings, and low transparency.

[0005] In the long term, there is an urgent need to develop a device and method to solve the above problems. Summary of the Invention

[0006] To address the shortcomings of existing technologies and problems with existing equipment, this invention discloses an integrated equipment and method for synthesizing high-purity quartz sand. This method aims to overcome the pollution problems caused by switching between multiple devices in traditional processes, while significantly reducing production costs and greatly improving production efficiency. In the integrated equipment, precisely proportioned raw materials undergo a liquid-phase reaction to prepare a sol. Subsequently, key processes such as directional molding and cleaning are sequentially completed within the same equipment. After sintering, high-quality synthetic quartz sand with a closed-pore structure, low hydroxyl content, high purity, and no black spots is finally obtained.

[0007] To achieve the above objectives, the technical solution adopted by this invention includes: This invention provides an integrated device for synthesizing high-purity quartz sand. The integrated device includes a vessel body with a jacket 2, which is composed of upper and lower parts: an upper cylindrical cavity and a lower inverted conical cavity. The cylindrical cavity is provided with a cover 11 at the top, and the cover 11 is provided with a feed pipe 14 and a discharge pipe 13. The bottom of the inverted conical cavity is provided with a discharge port 15. The vessel body is equipped with a stirring device 3, which is driven to rotate by a motor 1. The integrated device also includes an airflow assist system 25 for controlling the input of gas from the feed pipe 14 and the output of gas from the discharge pipe 13.

[0008] Optionally, the airflow assist system 5 includes a valve assembly 17, a heater 18, and a controller 20. The valve assembly 17 is provided with a first inlet 23, a first outlet 24, a second inlet, and a second outlet. The first inlet 23 is used to connect to a gas source. Gas enters the feed pipe 14 through the second outlet. The second inlet is connected to the discharge pipe 13. Gas is condensed and recovered after passing through the second inlet and the first outlet 24. The heater 18 is located at the first inlet 23 and is used to heat the gas source. The valve group 17 and heater 18 are communicatively connected to the controller 20.

[0009] Optionally, a first temperature sensor 21 is provided at the top of the vessel body, and a second temperature sensor 22 is provided at the bottom of the vessel body. The first temperature sensor 21 and the second temperature sensor 22 are communicatively connected to the controller 20.

[0010] Optionally, the stirring device 3 includes a stirring shaft and three layers of blades 4.

[0011] Optionally, the number of blades in the upper and middle layers is four, and the number of blades in the lower layer is two.

[0012] Optionally, the blades in the upper and middle layers are symmetrically distributed, and the blades in the lower layer are movably connected to the stirring shaft via a movable joint 5.

[0013] Optionally, the blade 4 has multiple semi-circular cuts at its end, the diameter of which is 0.8~3mm.

[0014] Optionally, the inner wall of the cylindrical cavity is provided with a first set of folding plates 6, and the inner wall of the inverted conical cavity is provided with a second set of folding plates 27.

[0015] Optionally, the first set of folding plates 6 and the second set of folding plates 27 are distributed in an alternating manner on the circumference.

[0016] Optionally, the top of the cap 11 is provided with an annular cavity 12, the annular cavity 12 is provided with an inlet pipe 7 and an outlet pipe 9, the inlet pipe 7 is connected to the top of the jacket 2, and the bottom of the jacket 2 is provided with a heat source medium inlet 8.

[0017] The present invention also provides a method for synthesizing high-purity quartz sand, the method comprising sol, molding, cleaning and calcination, wherein the sol, molding and cleaning are performed in the aforementioned integrated equipment.

[0018] Optionally, the method includes: Sol: Prepare an aqueous solution containing silicon powder and accelerator, add a silicon source under stirring and inert gas protection, and react to form a silica sol solution; Molding: Stop stirring, introduce inert gas, heat to form a gel solid, turn on stirring, break the gel solid into particles, and perform desolventizing treatment; Cleaning: The particles are soaked and cleaned with water, and then dried. Calcination: The particles are sintered to obtain high-purity quartz sand.

[0019] Optionally, during the sol-gel process, the molar ratio of the silicon source, water and accelerator is 1:5~50:0.0005~0.05, and the added mass of silicon powder accounts for 0.005%~0.5% of the total mass of the silicon source, water and accelerator.

[0020] Optionally, the silicon powder has a particle size range of 0.3~10μm and a purity of ≥99.999%.

[0021] Optionally, the silicon source is selected from at least one of alkoxysilanes and their oligomers, preferably tetramethoxysilane or tetraethoxysilane, and the purity of the silicon source is ≥99.999%.

[0022] Optionally, the accelerator is selected from at least one of formic acid, acetic acid, lactic acid, citric acid, ammonia, and amine organic bases, with a purity ≥99.999%.

[0023] Optionally, during the sol-gel process, the stirring rate is 75~180 r / min, the stirring temperature is 20~100℃, and the stirring time is 3~24 h.

[0024] Optionally, during the molding process, the heating temperature is 25~95℃ and the heating time is 0.5~48h.

[0025] Optionally, during the molding process, the crushing speed is 2~15 r / min and the particle size is 0.5~5 mm.

[0026] Optionally, during the cleaning process, the soaking time is 6 to 24 hours, the amount of water used is 0.5 to 5 times the mass of the sol, and the mass of the sol is the sum of the mass of the aqueous solution and the mass of the silicon source.

[0027] Optionally, the drying process includes drying at 120~250℃ for 6~24 hours.

[0028] Optionally, the roasting process is carried out at a temperature of 800~1400°C for 6~48 hours.

[0029] Optionally, the inert gas is nitrogen or helium with a purity ≥99.995%, an inert gas temperature of 25~250℃, and a flow rate of 5~25L / min.

[0030] The beneficial effects of this invention include: This invention discloses an integrated equipment and method for synthesizing high-purity quartz sand. The ingeniously designed integrated equipment effectively solves the contamination problems easily introduced during traditional multi-equipment switching processes, significantly reducing production costs while greatly improving production efficiency. Through the integrated design, continuous operation is achieved in key processes from material liquid-phase reaction, sol preparation, directional molding to cleaning, effectively avoiding the contamination risks associated with multi-equipment switching and ensuring high purity and high quality of the product. Furthermore, through an airflow-assisted system, this invention can precisely control the thermosetting and directional molding processes, ensuring no organic residue in the product. This preparation method is not only highly efficient and rapid but also particularly suitable for the industrial-scale production of artificially synthesized high-purity quartz sand, providing a more advanced, reliable, and economically beneficial new solution for related industries. Attached Figure Description

[0031] Figure 1 This is a process flow diagram of the method for synthesizing high-purity quartz according to the present invention.

[0032] Figure 2 This is a structural diagram of the integrated equipment for synthesizing high-purity quartz sand according to the present invention.

[0033] Figure 3 This is a schematic diagram of the airflow assist system of the present invention.

[0034] In the diagram, 1. Motor; 2. Jacket; 3. Stirring device; 4. Blade; 5. Movable joint; 6. First set of baffles; 7. Inlet pipe; 8. Heat source medium inlet; 9. Outlet pipe; 10. Lifting eye bolt; 11. Cover; 12. Annular cavity; 13. Discharge pipe; 14. Inlet pipe; 15. Discharge port; 16. Butterfly valve; 17. Valve group; 18. Heater; 19. Branch circuit; 20. Controller; 21. First temperature sensor; 22. Second temperature sensor; 23. First inlet; 24. First outlet; 25. Airflow auxiliary system; 26. Metering pump; 27. Second set of baffles. Detailed Implementation

[0035] The following description, in conjunction with the accompanying drawings, describes preferred embodiments in a more accessible manner so that the advantages and features of the present invention can be more readily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0036] The integrated equipment of the present invention includes a jacketed vessel body lined with polytetrafluoroethylene or similar materials. The vessel body is composed of two parts: an upper cylindrical cavity and a lower inverted conical cavity. The top of the cylindrical cavity is provided with a cover, and the cover is provided with an inlet pipe and an outlet pipe. The bottom of the inverted conical cavity is provided with a discharge port. The vessel body is equipped with a stirring device driven by a motor. The integrated equipment also includes an airflow auxiliary system to control the gas input from the inlet pipe and the gas output from the outlet pipe to achieve heat treatment curing.

[0037] The airflow assist system includes a valve assembly, a heater, and a controller. The valve assembly has a first inlet, a first outlet, a second inlet, and a second outlet. The first inlet is used to connect to a gas source. Gas enters the feed pipe through the second outlet. The second inlet is connected to the discharge pipe. After circulating inside the vessel, the gas is condensed and recovered after passing through the discharge pipe, the second inlet, and the first outlet. The heater is located at the first inlet to heat the gas source. The valve assembly and the heater are communicatively connected to the controller. A first temperature sensor is located at the top of the vessel, and a second temperature sensor is located at the bottom of the vessel. The first and second temperature sensors are communicatively connected to the controller. The temperature range of the first and second temperature sensors is 25~250℃.

[0038] The stirring device is made of polytetrafluoroethylene and includes a stirring shaft and three layers of blades. The upper and middle layers have four blades each, and the lower layer has two blades. The blades in the upper and middle layers are symmetrically distributed, and the blades in the lower layer are movably connected to the stirring shaft through a movable joint. The blades can adjust their angle according to the state of the material. The blades have multiple semi-circular cuts at their ends, and the diameter of the semi-circular cuts is 0.8~3mm.

[0039] The cylindrical cavity has a first set of folding plates on its inner wall, and the inverted conical cavity has a second set of folding plates on its inner wall; the first set of folding plates and the second set of folding plates are distributed in an alternating manner on the circumference.

[0040] The top of the cap is provided with an annular cavity, and the annular cavity is provided with an inlet pipe and an outlet pipe. The inlet pipe is connected to the top jacket of the vessel body. The bottom jacket of the vessel body is provided with a heat source medium inlet. The heat source medium enters the jacket through the heat source medium inlet, enters the annular cavity through the inlet pipe, and then flows out through the outlet pipe to form a circulating heat supply.

[0041] like Figure 1 As shown, the method of the present invention includes sol-gel, molding, cleaning, and calcination, wherein the sol-gel, molding, and cleaning are carried out in the integrated equipment. The integrated equipment stirs silicon powder, silicon source, accelerator, etc., of the required particle size into a sol, and further heat-treats it to solidify it. Subsequently, after molding within the equipment cavity, it undergoes solvent removal and cleaning, drying, and calcination to synthesize high-purity quartz sand. Specifically, it includes the following steps: Step 1, Sol: Silicon powder of suitable particle size, pure water, and accelerator are mixed in a specific ratio and then fed into the integrated equipment via a metering pump through the feed pipe. The stirring device is activated to stir the mixture into a solution. With the assistance of an airflow system, an inert atmosphere is created within the integrated equipment using inert gas for protection. Residual solution in the feed pipe is then removed. Similarly, the silicon source is added, and a suitable stirring speed is set. The temperature and reaction time are controlled by a first temperature sensor and a second temperature sensor to obtain a silica sol solution.

[0042] During the sol-gel process, the molar ratio of silicon source, water, and accelerator is 1:5~50:0.0005~0.05, and the mass ratio of silicon powder added is 0.005%~0.5% of the total mass of silicon source, water, and accelerator; the particle size of the silicon powder is 0.3~10μm, and the purity is ≥99.999%; the silicon source is selected from at least one of alkoxysilanes and their oligomers, preferably tetramethoxysilane or tetraethoxysilane, and the purity of the silicon source is ≥99.999%; the accelerator is selected from at least one of formic acid, acetic acid, lactic acid, citric acid, ammonia, and amine organic bases, and the purity is ≥99.999%; during the sol-gel process, the stirring rate is 75~180r / min, the stirring temperature is 20~100℃, and the stirring time is 3~24h.

[0043] Step 2, Molding: Stop stirring and keep the mixture still. Set a suitable temperature and inert gas flow rate using the heater in the airflow-assisted system to drive away excess organic components (methanol). Control the heating temperature using the first and second temperature sensors, and adjust the valve group for appropriate venting using the controller in the airflow-assisted system to maintain a constant pressure and form a gel solid. Restart stirring, and under the action of the stirring device, cut the mixture into approximately spherical particles with a particle size controlled within the range of 0.5~5mm. Immediately afterwards, increase the heater temperature and gas flow rate using the controller to desolventize the particles. The internal solvent is discharged through the first outlet in the valve group under the influence of the airflow and is condensed and recovered.

[0044] During the molding process, the heating temperature is 25~95℃ and the heating time is 0.5~48h; during the molding process, the crushing speed is 2~15r / min and the particle size is 0.5~5mm.

[0045] Step 3, Cleaning: In the same manner, stop the jacket heating and the heater heating. Referring to Step 1, pure water is introduced through the feed pipe by the gas source to soak and clean the above-mentioned desolvated particles, and then dry them at a suitable temperature and time.

[0046] During the cleaning process, the soaking time is 6 to 24 hours, the amount of water used is 0.5 to 5 times the mass of the sol, and the mass of the sol is the sum of the mass of the aqueous solution and the mass of the silicon source; the drying treatment includes drying at 120 to 250°C for 6 to 24 hours.

[0047] Step 4, Calcination: The above particles are discharged from the discharge port and placed into a quartz crucible for sintering to obtain high-purity synthetic quartz sand; during the calcination process, the temperature is 800~1400℃ and the time is 6~48h.

[0048] The inert gas described in this invention is nitrogen or helium with a purity ≥99.995%, an inert gas temperature of 25~250℃, and a flow rate of 5~25L / min. Example 1

[0049] like Figure 2 As shown, the integrated equipment of the present invention includes a vessel body with a jacket 2, the vessel body being lined with polytetrafluoroethylene. The vessel body is composed of two parts: an upper cylindrical cavity and a lower inverted conical cavity. The top of the cylindrical cavity is provided with a cover 11, which is fixedly connected by a lifting eye bolt 10. The cover 11 is provided with a feed pipe 14 and a discharge pipe 13. The bottom of the inverted conical cavity is provided with a discharge port 15, which is opened and closed by a butterfly valve 16. The vessel body is provided with a stirring device 3, which is driven to rotate by a motor 1. The integrated equipment also includes an airflow auxiliary system 25, which is used to control the gas input from the feed pipe 14 and the gas output from the discharge pipe 13 to achieve heat treatment curing.

[0050] like Figure 3 As shown, the airflow assist system 25 includes a valve group 17, a heater 18, and a controller 20. The valve group 17 is provided with a first inlet 23, a first outlet 24, a second inlet, and a second outlet. The first inlet 23 is used to connect to a gas source. Gas enters the feed pipe 14 through the second outlet. The second inlet is connected to the discharge pipe 13. After circulating inside the vessel, the gas is condensed and recovered after passing through the discharge pipe 13, the second inlet, and the first outlet 24. The heater 18 is located at the first inlet 23 to heat the gas source. The valve group 17 and the heater 18 are communicatively connected to the controller 20. A first temperature sensor 21 is provided at the top of the vessel, and a second temperature sensor 22 is provided at the bottom of the vessel. The first temperature sensor 21 and the second temperature sensor 22 are communicatively connected to the controller 20.

[0051] The feed pipe 14 is designed with a branch 19 for material entry, and the controller 20 realizes material input by coordinating and controlling the metering pump 26.

[0052] The stirring device 3 is made of polytetrafluoroethylene and includes a stirring shaft and three layers of blades 4. The upper and middle layers have four blades each, and the lower layer has two blades. The blades in the upper and middle layers are symmetrically distributed. The blades in the lower layer are movably connected to the stirring shaft through a movable joint 5. The end of the connecting shaft near the blades is also movably connected through a movable joint 5. The blades can adjust their angle according to the state of the material. The blades 4 are thin metal sheets with multiple semi-circular cuts at the ends. The diameter of the semi-circular cuts is 1 mm.

[0053] The cylindrical cavity has a first set of folding plates 6 on its inner wall, and the inverted conical cavity has a second set of folding plates 27 on its inner wall; the first set of folding plates 6 and the second set of folding plates 27 are distributed in an alternating manner on the circumference. Both the first set of folding plates 6 and the second set of folding plates 27 have four folding plates.

[0054] The top of the cap 11 is provided with an annular cavity 12. The annular cavity 12 is provided with an inlet pipe 7 and an outlet pipe 9. The inlet pipe 7 is connected to the top jacket of the vessel body. The bottom jacket of the vessel body is provided with a heat source medium inlet 8. The heat source medium enters the jacket 2 through the heat source medium inlet 8, enters the annular cavity 12 through the inlet pipe 7, and then flows out through the outlet pipe 9 to form a circulating heat supply. Example 2

[0055] High-purity quartz sand was synthesized using the integrated equipment described in Example 1.

[0056] Step 1, Sol: Mix 0.063 kg of 5 μm silica powder, 64.85 kg of pure water, and 0.39 kg of lactic acid. Then, use metering pump 26 to feed the mixture into the integrated equipment through feed pipe 14. Start the stirring device 3 to stir the mixture into a solution. Under the action of the airflow auxiliary system 25, using nitrogen as the inert gas, set the airflow rate to 12 L / min to create an inert atmosphere for protection within the integrated equipment. Clean any residual solution from feed pipe 14. Similarly, add 50 kg of tetraethoxysilane. Stir at 116 r / min. Heat is supplied by a heat source at 70°C in jacket 2. The reaction in the reactor is controlled at 65°C by temperature sensors 21 (62°C) and 22 (68°C), and the reaction time is 20 h to obtain a silica sol solution. Step 2, Molding: Stop stirring and keep the mixture still. Using the airflow-assisted system 25, set the temperature of the heater 18 to 120°C. Under nitrogen protection, introduce nitrogen at a flow rate of 5 L / min. The temperature is controlled by the first temperature sensor 21 (92°C) and the second temperature sensor 22 (98°C). The heat source controls the temperature inside the reactor to 95°C. The controller 20 regulates the valve group 17 for appropriate venting, forming a gel solid. Restart stirring at a serrated stirring speed of 4 r / min, cutting the particles into approximately spherical particles with a particle size controlled within the range of 0.5~5 mm. Next, adjust the heater 18 to 230°C and increase the gas flow rate to 17 L / min to desolventize the particles. The internal solvent, driven by the airflow, is discharged through the first outlet 24 in the valve group 17 and condensed for recovery.

[0057] Step 3, Cleaning: Following the same method, stop the jacketed heat source heating and heater 18 heating. Referring to Step 1, introduce 120 kg of pure water through the feed pipe 14 to soak the desolventized particles for 12 hours. Clean for 2 hours with stirring at 4 r / min. Reheat the temperature inside the reactor to 200℃ using the jacketed heat source and to 230℃ using heater 18. With the first temperature sensor 21 at 225℃ and the second temperature sensor 22 at 235℃, set the airflow to 22 L / min under nitrogen flow for dehydration and drying for 22 hours. Take the currently formed particles and calcine them at 300℃ for 10 hours. The organic content was measured to be 278 ppm using a LECO CS744 carbon-sulfur analyzer (USA).

[0058] Step 4, Calcination: The above-mentioned particles are discharged from the discharge port 15 and placed into a quartz crucible for sintering, that is, calcined at 800℃ for 10h, 900℃ for 3h, 1200℃ for 20h, and 1350℃ for 5h to obtain high-purity synthetic quartz sand.

[0059] Analysis was performed using an Agilent 7900 ICP-MS analyzer, and the purity was 6N8 (99.99998%). The product was used, and the purity was measured at a wavelength of 3600 cm⁻¹. -1 The infrared absorption intensity at the left and right sides was converted using Lambert-Beer's law, yielding a hydroxyl number of 33 ppm. Additionally, 10g of the finished product was weighed and spread flat on a white cardboard sheet to a thickness of approximately 1mm. The total number of black, brown, and yellow particles was found to be 0. Example 3

[0060] Following the same synthesis process as in Example 2, the specific difference is as follows: 50 kg of methyl silicate oligomer (SiO2 content 48%~51%) was mixed with 20.62 kg of ultrapure water, 0.16 kg of acetic acid, and 0.02 kg of silica powder to form a sol. After undergoing the same steps as in Example 2, high-purity synthetic quartz sand was obtained.

[0061] Analysis of the finished product showed that the organic content in the shaped granules was 312 ppm. The hydroxyl count of the calcined sample was 37 ppm, the purity was 6N2 (99.99992%), and the total number of black spot impurities observed by the naked eye was 0 per 10g. Example 4

[0062] Following the same synthesis process as in Example 2, the specific difference is as follows: 25 kg of tetramethoxysilane, 73.97 kg of ultrapure water, 0.51 kg of 28% ammonia, and 0.025 kg of silica powder are mixed to form a sol. After undergoing the same steps as in Example 2, high-purity synthetic quartz sand is obtained.

[0063] Analysis of the finished product showed that the organic content in the shaped granules was 341 ppm. The hydroxyl count of the calcined sample was 35 ppm, the purity was 6N5 (99.99995%), and the total number of black spot impurities observed by the naked eye was 0 per 10g. Comparative Example 1

[0064] According to Example 2, using the same sol-gel method, a conventional box-type drying device was used to dry the particles at 180°C for 36 hours. Then, a double-roll crusher was used with the rotation speed adjusted to 300 r / min and the roller spacing to 0.3 mm to form particles of 0.5~5 mm. After sieving, it was observed that the particle morphology was uneven, the particle fullness was low, the sphericity was poor, and the proportion of fine powder smaller than 40 μm was close to 23%, resulting in a low yield. The residual organic component was measured to be 4150 ppm.

[0065] Subsequently, the gel particles were loaded into a quartz crucible and placed in a calcining furnace for calcination under the same calcination conditions to obtain synthetic quartz sand with a purity of 5N2 (99.9992%). The number of hydroxyl groups was measured to be 128 ppm by infrared equipment, and the number of black particles was observed to be 10 per 10g. Comparative Example 2

[0066] Following Example 4, the same sol-gel method was used to pack the obtained silica sol into a plastic bucket. After gelation using the same constant temperature process, a rotary disc crusher was used with the rotation speed adjusted to 600 r / min and the disc gap to 0.6 mm to form particles of 0.5~5 mm. After sieving, the particles were washed three times with twice the volume of pure water and then dried at 200°C for 24 hours using a traditional box-type drying equipment. The residual amount of organic components was measured to be 4320 ppm.

[0067] Subsequently, the gel particles were loaded into a quartz crucible and placed in a calcining furnace for calcination under the same calcination conditions to obtain synthetic quartz sand with a purity of 4N8 (99.998%). The number of hydroxyl groups was measured to be 221 ppm by infrared equipment, and the number of black particles was 15 per 10g.

[0068] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. An integrated device for synthesizing high-purity quartz sand, characterized in that, The integrated device includes a vessel body with a jacket (2), which is composed of two parts: an upper cylindrical cavity and a lower inverted conical cavity. The top of the cylindrical cavity is provided with a cover (11), and the cover (11) is provided with a feed pipe (14) and a discharge pipe (13). The bottom of the inverted conical cavity is provided with a discharge port (15). The vessel body is equipped with a stirring device (3), which is driven to rotate by a motor (1). The integrated device also includes an airflow assist system (25) for controlling the input of gas from the feed pipe (14) and the output of gas from the discharge pipe (13).

2. The integrated device according to claim 1, characterized in that, The airflow assist system (25) includes a valve group (17), a heater (18), and a controller (20). The valve group (17) is provided with a first inlet (23), a first outlet (24), a second inlet, and a second outlet. The first inlet (23) is used to connect to a gas source. Gas enters the feed pipe (14) through the second outlet. The second inlet is connected to the discharge pipe (13). Gas is condensed and recovered after passing through the second inlet and the first outlet (24). The heater (18) is located at the first inlet (23) for heating the gas source. The valve group (17), heater (18) and controller (20) are connected in communication. Preferably, a first temperature sensor (21) is provided at the top of the vessel body, and a second temperature sensor (22) is provided at the bottom of the vessel body. The first temperature sensor (21) and the second temperature sensor (22) are communicatively connected to the controller (20).

3. The integrated device according to claim 1 or 2, characterized in that, The stirring device (3) includes a stirring shaft and three layers of blades (4). Preferably, the number of blades in the upper and middle layers is four, and the number of blades in the lower layer is two; Preferably, the blades in the upper and middle layers are symmetrically distributed, and the blades in the lower layer are movably connected to the stirring shaft through a movable joint (5); Preferably, the blade (4) has multiple semi-circular cuts at its end, and the diameter of the semi-circular cuts is 0.8~3mm.

4. The integrated device according to any one of claims 1 to 3, characterized in that, The inner wall of the cylindrical cavity is provided with a first set of folding plates (6), and the inner wall of the inverted conical cavity is provided with a second set of folding plates (27). Preferably, the first set of folding plates (6) and the second set of folding plates (27) are distributed in an alternating manner on the circumference.

5. The integrated device according to any one of claims 1 to 4, characterized in that, The top of the cap (11) is provided with an annular cavity (12), and the annular cavity (12) is provided with an inlet pipe (7) and an outlet pipe (9). The inlet pipe (7) is connected to the top of the jacket (2), and the bottom of the jacket (2) is provided with a heat source medium inlet (8).

6. A method for synthesizing high-purity quartz sand, characterized in that, The method includes sol-gelling, molding, cleaning, and calcination, wherein the sol-gelling, molding, and cleaning are performed in the integrated equipment described in any one of claims 1 to 5.

7. The method according to claim 6, characterized in that, The method includes: Sol: Prepare an aqueous solution containing silicon powder and accelerator, add a silicon source under stirring and inert gas protection, and react to form a silica sol solution; Molding: Stop stirring, introduce inert gas, heat to form a gel solid, turn on stirring, break the gel solid into particles, and perform desolventizing treatment; Cleaning: The particles are soaked and cleaned with water, and then dried. Calcination: The particles are sintered to obtain high-purity quartz sand.

8. The method according to claim 6 or 7, characterized in that, During the sol-gel process, the molar ratio of the silicon source, water, and accelerator is 1:5~50:0.0005~0.05, and the added silicon powder accounts for 0.005%~0.5% of the total mass of the silicon source, water, and accelerator. And / or, the silicon powder has a particle size range of 0.3~10μm and a purity ≥99.999%; And / or, the silicon source is selected from at least one of alkoxysilanes and their oligomers, preferably tetramethoxysilane or tetraethoxysilane, and the purity of the silicon source is ≥99.999%; And / or, the accelerator is selected from at least one of formic acid, acetic acid, lactic acid, citric acid, ammonia, and amine organic bases, with a purity ≥99.999%; And / or, during the sol-gel process, the stirring rate is 75~180 r / min, the stirring temperature is 20~100℃, and the stirring time is 3~24 h.

9. The method according to any one of claims 6 to 8, characterized in that, During the molding process, the heating temperature is 25~95℃, and the heating time is 0.5~48h; And / or, during the molding process, the crushing speed is 2~15 r / min, and the particle size is 0.5~5 mm; And / or, during the cleaning process, the soaking time is 6 to 24 hours, the amount of water used is 0.5 to 5 times the mass of the sol, and the mass of the sol is the sum of the mass of the aqueous solution and the mass of the silicon source; And / or, the drying process includes drying at 120~250℃ for 6~24h; And / or, during the roasting process, the temperature is 800~1400°C and the time is 6~48h.

10. The method according to any one of claims 6 to 9, characterized in that, The inert gas is nitrogen or helium with a purity ≥99.995%, an inert gas temperature of 25~250℃, and a flow rate of 5~25L / min.

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