Manufacturing process for high-purity quartz sand by liquid phase hydrolysis of silicon tetrachloride

Abstract

The application discloses a manufacturing process of high-purity quartz sand by a liquid-phase hydrolysis method of silicon tetrachloride, which comprises the following process steps in sequence: liquid-phase hydrolysis of silicon tetrachloride and water, and then washing, solid-liquid separation, drying, calcination, grinding and screening of the hydrolysis product to finally obtain high-purity quartz powder; the solid-liquid separation is simultaneously provided with a heating process or the heating process is arranged between the washing process and the solid-liquid separation process; or the washing process is simultaneously provided with the heating process. The orthosilicic acid in the hydrolysis product is more easily decomposed into metasilicic acid due to heating; thus, almost all of the metasilicic acid is obtained during the solid-liquid separation, and only the filter residue of metasilicic acid particles is obtained on the filter screen, which is easy to transfer and avoids the problem that the filter residue of the colloidal orthosilicic acid is not easy to transfer. The loss of the orthosilicic acid is avoided as much as possible, the raw material consumption is reduced, the preparation cost is lowered, and the filter screen is easy to clean.

Description

Technical Field

[0001] This invention relates to the preparation of finely dispersed silica that is neither in a sol-like nor a gel-like state; and its subsequent processing, specifically to a manufacturing process for synthesizing high-purity quartz sand by liquid-phase hydrolysis of silicon tetrachloride. Background Technology

[0002] High-purity quartz powder is prepared using the SiCl4 liquid-phase hydrolysis method. Because the raw materials do not contain carbon, the resulting SiO2 powder has high purity and low hydroxyl content. Xu Hua's paper "Preparation of Silica Microspheres by Hydrolysis of Silicon Tetrachloride in Microemulsions" published in *Inorganic Salt Industry*, Vol. 49, No. 12, December 2017, and Zhang Xiangjing's paper "Research on the Process of Preparing Nano-Silica Powder by Hydrolysis of Silicon Tetrachloride" published in *Inorganic Salt Industry*, Vol. 45, No. 10, October 2013, demonstrate that existing technologies have some research on preparing small-particle-size silica powder (with particle sizes in the nanometer range, no longer belonging to quartz sand) from silicon tetrachloride. However, research on the preparation of quartz sand using the silicon tetrachloride liquid-phase hydrolysis method is limited. Patent CN114835130A discloses a method for producing high-purity quartz. The method involves grinding quartz sand and carbonaceous materials into powder, drying them, mixing the powder, and then adding chlorine gas to a high-temperature reactor for a chlorination reaction to prepare silicon tetrachloride. The collected silicon tetrachloride is first removed by an adsorption device to remove trace impurities such as boron, phosphorus, carbon-hydrogen bonds, and hydrogen-oxygen bonds. It is then purified through multi-stage distillation (using a light component removal tower, a heavy component removal tower, a mechanical distillation tower, and a heavy component removal tower) to remove light and heavy component impurities. After distillation, trace solid particles and metal ion impurities are removed by membrane separation. Finally, high-purity quartz is obtained using liquid-phase hydrolysis. Silicon tetrachloride undergoes liquid-phase hydrolysis upon contact with pure water. The hydrolysis product is then washed, separated from solid by liquid, dried, calcined, ground, and sieved to finally obtain high-purity quartz powder. The hydrolysis process involves SiCl4 contacting with pure water to undergo a hydrolysis reaction. The conventional process for preparing SiO2 powder involves washing, filtering, drying, calcining, and screening the reaction products. However, the products of the liquid-phase hydrolysis of silicon tetrachloride with water include hydrogen chloride, orthosilicic acid, and metasilicic acid. Orthosilicic acid typically appears as a white, colloidal precipitate, while metasilicic acid is an amorphous particle (colorless, transparent crystals, sometimes also a white powder). If the reaction products are washed and then filtered, in addition to solid filter residue, there will be colloidal filter residue on the filter screen. Transferring the filter residue is inconvenient, and some orthosilicic acid will inevitably be lost, increasing the amount of raw materials used and raising the production cost. Moreover, cleaning the filter screen is also inconvenient. Furthermore, in large-scale production, the hydrolysis and condensation reactions of silicon tetrachloride with water are intense, and the intermediate processes are difficult to control, making the powder prone to agglomeration. Summary of the Invention

[0003] The purpose of this invention is to overcome the defects in the existing technology and provide a manufacturing process for synthesizing high-purity quartz sand by liquid-phase hydrolysis of silicon tetrachloride. The orthosilicic acid in the hydrolysis product is more easily decomposed into metasilicic acid due to heating. In this way, when solid-liquid separation is performed, it is almost entirely metasilicic acid. The filter screen only contains metasilicic acid particles as filter residue, which is easy to transfer and avoids the problem of poor transfer of colloidal orthosilicic acid filter residue.

[0004] To achieve the above objectives, the technical solution of the present invention is to design a manufacturing process for synthesizing high-purity quartz sand by liquid-phase hydrolysis of silicon tetrachloride, which consists of the following sequential process steps: silicon tetrachloride undergoes liquid-phase hydrolysis with water, and then the hydrolysis product is subjected to washing, solid-liquid separation, drying, calcination, grinding and sieving processes to finally obtain high-purity quartz powder.

[0005] The solid-liquid separation process may include a heating step, or a washing step may be placed between the solid-liquid separation and washing processes; or a heating step may be placed simultaneously with the washing process. Alternatively, the heating step can be incorporated into the washing process to further reduce process complexity. For example, warm water at 40-55°C can be used for washing, so that the orthosilicic acid in the hydrolysis products is more easily decomposed into metasilicic acid due to heating. In this way, during solid-liquid separation, almost all of the product is metasilicic acid, and the filter screen contains only metasilicic acid particles as filter residue, which is easy to transfer and avoids the problem of difficult transfer of colloidal orthosilicic acid filter residue.

[0006] A further technical solution is that the temperature of the drying process is 100~200℃, the filter residue is placed in a constant temperature box to dehydrate and dry to constant weight and then transferred to a calcining furnace, and the calcination temperature of the calcination process is 1300~1500℃.

[0007] A further technical solution is that the heating process involves heating the filter residue on the filter screen involved in the solid-liquid separation process or heating the washed product.

[0008] A further technical solution is that the calcination furnace in the calcination process consists of a furnace body, a furnace shell disposed outside the furnace body, a heating component disposed between the furnace shell and the furnace body, and a drive mechanism disposed outside the furnace body to drive the furnace body to rotate. The heating component includes several spaced direct-fired heating ports disposed on the lower outer side of the furnace body. The length of the furnace shell is less than that of the furnace body. The drive mechanism is located near both ends of the furnace body along the length of the furnace body. The drive mechanism is located below the furnace body and outside the furnace shell. The direct-fired heating ports are located inside the furnace shell. A direct-fired heating port is set on the lower outer side of the rotating furnace body, which is exactly in front of the part of the furnace body where more material accumulates (although the material in the furnace cavity rotates with the furnace, due to its own weight, more material accumulates in the middle and lower part of the furnace cavity. Therefore, setting the direct-fired heating port on the lower outer side of the furnace body can ensure that more material is heated. From the perspective of the material distribution in the furnace cavity, this setting of the heating port is also a perfect match, which can better ensure the uniformity of the calcination process, better control the particle size distribution of quartz sand, avoid the generation of excessively fine particles, and effectively prevent the agglomeration of quartz sand powder).

[0009] A further technical solution involves a drive mechanism comprising a drive motor, a transmission connected to the drive motor, a gear fixedly mounted on the output shaft of the transmission, a gear ring meshing with the gear, the gear ring being fixedly connected to the outer wall of the furnace body, and an annular belt fixedly mounted on the outer wall of the furnace body, with a support roller adapted to the belt. By starting the drive motor, the transmission rotates, which in turn drives the gear to rotate, thereby rotating the gear ring, which in turn rotates the furnace body, achieving rotary calcination. Combined with the inclined design of the furnace body, calcination and material conveying can be achieved simultaneously.

[0010] A further technical solution involves washing, solid-liquid separation, and drying of the hydrolysis products, which are then fed into the inlet of the calcining furnace. The furnace body is heated via a direct-fired heating port. The material enters the furnace and is conveyed simultaneously with the furnace's rotation, aided by the inclined furnace body. The material is discharged from the outlet. A furnace head hood and a furnace tail box are connected to both ends of the furnace body. A furnace head seal ensures airtightness between the furnace body and the furnace head hood, and a furnace tail seal ensures airtightness between the furnace body and the furnace tail box. The inlet is located on the furnace head hood, and the outlet is located on the furnace tail box. Spiral-distributed guide strips are fixedly installed on the inner wall of the furnace body near the furnace head hood to ensure the material entering the furnace cavity is distributed as evenly as possible (this helps to lift the material when the furnace rotates), preventing accumulation.

[0011] The advantages and beneficial effects of this invention are as follows: the orthosilicic acid in the hydrolysis products is more easily decomposed into metasilicic acid upon heating; thus, during solid-liquid separation, almost all of it is metasilicic acid, and the filter screen contains only metasilicic acid particles, which are easy to transfer, avoiding the problem of difficult transfer of colloidal orthosilicic acid precipitate. This minimizes the loss of orthosilicic acid, reduces raw material usage, lowers preparation costs, and makes the filter screen easier to clean.

[0012] A direct-fired heating port is set on the lower outer side of the rotating furnace body, which is exactly in front of the part of the furnace body where more material accumulates (although the material in the furnace cavity rotates with the furnace, due to its own weight, more material accumulates in the middle and lower part of the furnace cavity. Therefore, setting the direct-fired heating port on the lower outer side of the furnace body can ensure that more material is heated. From the perspective of the material distribution in the furnace cavity, this setting of the heating port is also a perfect match, which can better ensure the uniformity of the calcination process, better control the particle size distribution of quartz sand, avoid the generation of excessively fine particles, and effectively prevent the agglomeration of quartz sand powder).

[0013] By starting the drive motor, the transmission device rotates, which in turn drives the gear to rotate, thereby driving the gear ring to rotate. This, in turn, drives the furnace body to rotate, achieving the effect of rotary calcination. In addition, the inclined setting of the furnace body allows for calcination and material conveying to be carried out simultaneously.

[0014] After washing, solid-liquid separation, and drying, the hydrolysis products are sent to the feed inlet of the calcining furnace. The furnace body is heated by a direct-fired heating port. After entering the furnace body, the material is conveyed simultaneously with the furnace rotation and the inclined furnace body. The material is discharged after reaching the discharge port. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the calcining furnace in Example 1 of the manufacturing process for synthesizing high-purity quartz sand by liquid-phase hydrolysis of silicon tetrachloride according to the present invention.

[0016] Figure 2 yes Figure 1 The main view;

[0017] Figure 3 yes Figure 2 A magnified view of a portion of the image;

[0018] Figure 4 yes Figure 2 Sectional view along axis AA;

[0019] Figure 5 yes Figure 2 CC-direction sectional view;

[0020] Figure 6 This is a schematic diagram of an example of the calcining furnace in Embodiment 2 of the present invention;

[0021] Figure 7 This is a schematic diagram of another example of the calcining furnace in Embodiment 2 of the present invention;

[0022] Figure 8 This is a schematic diagram of the solid-liquid separation device in Embodiment 3 of the present invention;

[0023] Figure 9This is a schematic diagram of the calcining furnace in Embodiment 4 of the present invention;

[0024] Figure 10 yes Figure 9 A diagram from another perspective;

[0025] Figure 11 This is a schematic diagram of the calcining furnace in Embodiment 5 of the present invention;

[0026] Figure 12 yes Figure 11 A schematic diagram of the longitudinal section;

[0027] Figure 13 yes Figure 11 The right view;

[0028] Figure 14 This is a schematic diagram of the calcining furnace in Embodiment Six of the present invention;

[0029] Figure 15 yes Figure 14 Side view;

[0030] Figure 16 yes Figure 14 Exploded view of the central round rod, round tube, and gear ring;

[0031] Figure 17 yes Figure 16 Another schematic diagram of its working state.

[0032] In the diagram: 1. Furnace body; 2. Furnace shell; 3. Direct-fired heating port; 4. Drive motor; 5. Transmission device; 6. Gear; 7. Gear ring; 8. Tire; 9. Support roller; 10. Furnace head cover; 11. Furnace tail box; 12. Feed inlet; 13. Discharge outlet; 14. Exhaust port; 15. Guide bar; 16. Filter screen; 17. Solid-liquid separation device; 18. Metal ring; 19. Plastic ring; 20. Sub-furnace body; 21. Dispersant addition port; 22. Support base; 23. Second support base; 24. Arc-shaped long plate; 25. Spring; 26. Spring piece; 27. Opening; 28. Round rod; 29. ​​Round tube; 30. Elastic ring. Detailed Implementation

[0033] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0034] Example 1: As Figures 1 to 5 As shown (for ease of illustration), Figure 1(Furnace shell not shown) This invention is a manufacturing process for synthesizing high-purity quartz sand via liquid-phase hydrolysis of silicon tetrachloride. Silicon tetrachloride undergoes liquid-phase hydrolysis with water, and the hydrolysis product is then subjected to washing, solid-liquid separation, drying, calcination, grinding, and sieving processes to ultimately obtain high-purity quartz powder. A heating process is included concurrently with the solid-liquid separation process, or a heating process is included between the washing and solid-liquid separation processes; or a heating process is included concurrently with the washing process. The drying process is carried out at a temperature of 100~200℃. The filter residue is placed in a constant temperature chamber for dehydration and drying until constant weight, and then transferred to a calcining furnace. The calcination process is carried out at a temperature of 1300~1500℃. The heating process involves heating the filter residue on the filter screen involved in the solid-liquid separation process (such as directly heating the filter screen or heating the filter container) or heating the washed product (so that the orthosilicic acid colloid in the solution is further decomposed into metasilicic acid, so that after heating and solid-liquid separation, only metasilicic acid particles remain on the filter screen, which are easy to transfer and avoid the problem of difficult transfer of colloidal precipitate filter residue). The hydrolysis product is sent to the feed inlet on the furnace body of the calcining furnace after washing, solid-liquid separation and drying. The furnace body is heated by a direct-fired heating port. After the material enters the furnace body, it is transported with the furnace as it rotates and is tilted. The material is discharged after reaching the discharge port.

[0035] The calcining furnace consists of a furnace body 1, a furnace shell 2 located outside the furnace body 1, a heating component located between the furnace shell and the furnace body, and a drive mechanism located outside the furnace body 1 to drive the furnace body to rotate. The heating component includes several spaced direct-fired heating ports 3 located on the lower outer side of the furnace body. The length of the furnace shell 2 is less than that of the furnace body. The drive mechanism is located near both ends of the furnace body along the length of the furnace body 1. The drive mechanism is located below the furnace body and outside the furnace shell 2, while the direct-fired heating ports 3 are located inside the furnace shell. The drive mechanism includes a drive motor 4, a transmission device 5 connected to the drive motor, a gear 6 fixedly mounted on the output shaft of the transmission device, a gear ring 7 meshing with the gear, the gear ring being fixedly connected to the outer wall of the furnace body, and an annular belt 8 fixedly mounted on the outer wall of the furnace body. A support roller 9 is fitted to the belt. The furnace body 1 is connected to a furnace head cover 10 and a furnace tail box 11 at its two ends, respectively. The furnace body and the furnace head cover are sealed by a furnace head seal, and the furnace body and the furnace tail box are sealed by a furnace tail seal. The feed inlet 12 is located on the furnace head cover 10, and the discharge outlet 13 is located on the furnace tail box 11. The furnace tail box is also provided with an exhaust outlet 14 opposite to the discharge outlet. Spiral guide strips 15 are fixedly installed on the inner wall of the furnace body 1 near the furnace head cover 10 to ensure that the material entering the furnace cavity is distributed as evenly as possible (and plays a role in lifting the material when the furnace body rotates), avoiding accumulation.

[0036] Example 2: The difference from Example 1 is that the furnace body 1 of the calcination furnace in the calcination process is equipped with several spaced filter screens 16, with the mesh size increasing along the calcination feeding direction; the filter screens are ceramic, stainless steel, or silicon-based ceramic; the filter screens are located near the discharge port of the calcination furnace (and only one is installed); thus, the furnace shell 2 and the direct-fired heating port 3 inside the furnace body 1 are positioned closer to the feed port and further away from the discharge port and exhaust port 14, such as... Figure 6 (as shown); or the filter screen 16 is provided at the feed inlet, discharge outlet, and middle of the furnace body (as shown). Figure 7 As shown in the diagram), the calcination furnace (a rotary kiln) in the calcination process has filters installed at each stage inside the furnace. This causes the agglomerated powder to accumulate on the filters. After the machine is stopped, the powder is graded and recycled according to particle size (or a single filter is installed at the discharge port; when the output decreases significantly, the filter is removed, and the agglomerated powder on the filter is mechanically dispersed and deagglomerated). The powder is then dispersed and deagglomerated using an air jet mill. This method differs from the previous approach of considering how to prevent agglomeration during preparation. Instead, deagglomeration is performed after the quartz sand is prepared, collecting the unagglomerated powder and then the deagglomerated quartz sand. This reduces the complexity of the preparation process and reduces or eliminates the use of dispersants. This also lowers the requirements for the calcination furnace and simplifies the technical modifications, requiring only the installation of filters with different mesh sizes at intervals within the furnace.

[0037] Example 3: The difference from Example 1 is that, as shown in Example 3... Figure 8 As shown, the solid-liquid separation device 17 used in the solid-liquid separation process can be a solid-liquid separation hydrocyclone, including a cylindrical device body. A filter screen is fixedly installed inside the device body. The device body is formed by a metal ring 18 located at the filter screen and plastic rings 19 located on both sides of the metal ring, which are fixedly and sealed together. The outer wall of the metal ring is connected to a heating wire. After the heating wire is activated, it transfers heat to the metal filter screen fixed inside the metal ring, thus heating the filter screen. This allows for precise heating of the filter screen, eliminating the need to heat the entire solid-liquid separation device and reducing heat waste. It also solves the problem of poor heating of the filter screen during solid-liquid separation.

[0038] Example 4: The difference from Example 2 is that, as shown in Example 2... Figure 9 , Figure 10 As shown (for ease of illustration), Figure 9 Only a portion of the furnace shell, a portion of the dispersant inlet, and a portion of the drive mechanism are shown; Figure 10(The furnace shell and dispersant inlet are not shown; only a drive mechanism is shown.) The calcining furnace body 1 is tilted and divided into sections. A decrease in the discharge from outlet 13 indicates that there is excessive agglomeration of quartz sand powder, causing blockage of filter screen 16. (By observing the material conveying situation inside each section of the furnace {i.e., when the material in a certain section of the furnace hardly exits from its lower filter screen or there is a significant accumulation of material on its lower filter screen}, it can be determined which section of the furnace is experiencing powder agglomeration.) The rotation of the section of the furnace where the powder agglomerates is located is accelerated. Dispersant is added between the two-stage filter screens 16 to accelerate rotation and deagglomerate, effectively controlling quartz powder agglomeration, reducing the amount of dispersant used, and achieving effective dispersant addition. The added dispersant can be polyethylene glycol, sodium dodecylbenzene sulfonate, etc.

[0039] The furnace body 1 is composed of several sub-furnace bodies connected by a rotary seal. Each sub-furnace body is equipped with a drive mechanism to realize the rotation of each sub-furnace body. When it is necessary to increase the speed of a certain sub-furnace body 20, the speed of the drive motor below it can be increased accordingly. The furnace shell is changed to be composed of several sub-furnace shells, and there is a gap between each sub-furnace shell. Each sub-furnace body is equipped with a dispersant inlet 21. A quartz glass window is provided on the sub-furnace body.

[0040] Example 5: The difference from Example 1 is that, as shown in Example 5... Figures 11 to 13 As shown (for ease of illustration), Figure 13 (The elastic structure is not shown in the diagram). The furnace body 1 is inclined, and a support base 22 is fixedly installed under the furnace shell 2. A second support base 23 is provided on one side of the furnace tail box 11. An elastic structure extending into the furnace body is fixedly installed on the second support base 23. The elastic structure includes an arc-shaped long plate 24 fixedly connected to the second support base 23. The arc-shaped long plate passes through the side wall of the furnace tail box and is sealed and fixedly connected at the connection point of the side wall of the furnace tail box. There is a gap between the arc-shaped long plate and the inner side wall of the furnace body, but the arc-shaped long plate is closer to the bottom of the furnace cavity in the height direction. The curvature of the arc-shaped long plate 24 is consistent with the curvature of the furnace cavity. Several springs 25 are arranged at intervals on the upper surface of the arc-shaped long plate. A spring piece 26 is fixedly installed on each spring. One end of the spring piece is fixedly connected to the spring, and the other end is hinged to the upper surface of the arc-shaped long plate. To better realize this solution, an opening 27 is provided on the outer side wall of the furnace tail box 11. The size of the opening is slightly larger than the cross-sectional size of the whole composed of the arc-shaped long plate and the spring piece. After the elastic structure extends into the furnace body, the opening is sealed with sealant.

[0041] When the material rotates with the furnace, it is lifted up upon contact with the spring plate. This causes any falling material to bounce towards the center of the furnace cavity, effectively dispersing the material as much as possible along the height of the furnace cavity. The tilting of the furnace body, combined with the elastic structure inside the furnace, ensures that the material, which is conveyed downwards while rotating with the furnace, is distributed as evenly as possible within the furnace cavity space. This results in a more uniform calcination process, better control of the particle size distribution of the quartz sand, and avoidance of excessively fine particles, thus effectively preventing the agglomeration of quartz sand powder.

[0042] Example 6: The difference from Example 4 is that, as Figures 14 to 17 As shown (for ease of illustration), Figure 14 Only one round rod and one round tube are shown; Figure 15 Only one drive mechanism is shown; the round rod and round tube are not shown. Figure 16 , Figure 17 In these two exploded diagrams, the gear ring moves laterally relative to the round rod or tube to clearly show the positional relationship between the elastic ring and the gear ring, as well as the positional relationship between the round tube and the round rod. The gear ring 7 in the drive mechanism is a relatively thick gear ring (so that the gear ring can be set outside the furnace shell 2). A round rod 28 is fixedly set on the side of one of the two adjacent gear rings, and a round hole is set on the side of the other (the center of the round hole and the center of the round rod are located on the same circle on the side of the gear ring, and this circle is concentric with the gear ring). A round tube 29 is set to match the round hole. The inner diameter of the round tube is larger than the diameter of the round rod, and the outer diameter of the round tube is smaller than the diameter of the round hole. A fixed sleeve is fitted on the round tube 29. Two elastic rings 30 are provided with a gap between them. The sum of the lengths of the round rod 28 and the round tube 29 is greater than the gap between two adjacent toothed rings 7. The round tube is inserted into the round hole to the first elastic ring 30 (the two elastic rings 30 are set at one of the tube openings near the round tube. When inserting, the tube opening away from the elastic ring is inserted into the round hole). After being inserted into the round hole, there is a gap between the tube opening away from the elastic ring 30 and the end of the round rod fixedly connected to the round tube relative to the toothed ring. After the round tube is inserted into the round hole to the second elastic ring 30, the end of the round rod 28 of the round tube 29 relative to the toothed ring is located inside the tube opening away from the elastic ring 30 of the round tube 29.

[0043] Each sub-furnace body is equipped with a drive mechanism; the furnace shell is changed to be composed of several sub-furnace shells, and there is a gap between each sub-furnace shell; each sub-furnace body is equipped with a dispersant injection port 21; and each sub-furnace body is equipped with a quartz glass viewing window.

[0044] With this setup, before starting the drive mechanism, insert the circular tube between every two adjacent toothed rings into the circular hole so that the second elastic ring 30 is inserted into the circular hole (the two elastic rings 30 are located at one end of the circular tube, and the end furthest from the elastic ring is inserted into the circular hole). Then, only one drive mechanism needs to be started to make all the sub-furnaces rotate together. When it is necessary to increase the speed of a certain sub-furnace 20 (a decrease in the discharge amount at the discharge port 13 indicates that the quartz sand powder has agglomerated too much, causing the filter screen 16 to be clogged), the material conveying situation inside each sub-furnace can be observed. When the material in a certain section of the furnace body hardly exits from the filter screen at its lower end, or when a lot of material has obviously accumulated on the filter screen at its lower end, it is possible to clearly identify which section of the furnace body has powder agglomeration. At the part of the furnace body where the powder agglomeration occurs, the rotation is accelerated. Then, the round tube is pulled outward so that the first elastic ring 30 of the round tube fits tightly with the round hole (the elastic ring is elastic, and when it fits with the round hole, it can ensure that the round tube does not slip and maintains its position). This prevents the round rod from being inserted into the opening of the round tube. At this time, the drive mechanism located below this section of the furnace body can be directly started to increase its rotation speed.

[0045] This allows all sub-furnaces to rotate together under normal conditions, and only a single sub-furnace needs to be accelerated at high speed. This reduces energy consumption. Furthermore, since the rotary calcining furnace itself does not rotate at high speed, the circular tube can be disconnected to accelerate a specific sub-furnace, making the operation simple.

[0046] Dispersant is still added between the two-stage filter screen 16 to accelerate the rotation and deagglomeration of quartz powder, effectively control the agglomeration of quartz powder, reduce the amount of dispersant used, and achieve effective dispersant addition.

[0047] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A manufacturing process for synthesizing high-purity quartz sand by liquid-phase hydrolysis of silicon tetrachloride, characterized in that, The process consists of the following sequential steps: silicon tetrachloride undergoes liquid-phase hydrolysis with water, and then the hydrolysis product is washed, separated from solid and liquid, dried, calcined, ground and sieved to finally obtain high-purity quartz powder; The solid-liquid separation process is combined with a heating process, or a heating process is combined between the washing process and the solid-liquid separation process; or a heating process is combined with the washing process; or the washing process uses warm water at 40~55℃. The calcination furnace in the calcination process consists of a furnace body, a furnace shell disposed outside the furnace body, a heating component disposed between the furnace shell and the furnace body, and a drive mechanism disposed outside the furnace body to drive the furnace body to rotate. The heating component includes several spaced direct-fired heating ports disposed on the lower outer side of the furnace body. The length of the furnace shell is less than that of the furnace body. The drive mechanism is located near both ends of the furnace body along its length. The drive mechanism is located below the furnace body and outside the furnace shell. The direct-fired heating ports are located inside the furnace shell. A filter screen is installed inside the furnace. The filter screen is made of ceramic or stainless steel. A filter screen is installed near the discharge port of the calcining furnace, or the filter screen is installed at the feed port, discharge port and middle of the furnace body. Several filter screens are installed at intervals in stages inside the furnace body, and the mesh size of the filter screen increases along the calcining feeding direction.

2. The manufacturing process for synthesizing high-purity quartz sand by liquid-phase hydrolysis of silicon tetrachloride according to claim 1, characterized in that, The drying process is carried out at a temperature of 100~200℃. The filter residue is placed in a constant temperature chamber for dehydration and drying until constant weight, and then transferred to a calcining furnace. The calcination process is carried out at a temperature of 1300~1500℃.

3. The manufacturing process for synthesizing high-purity quartz sand by liquid-phase hydrolysis of silicon tetrachloride according to claim 2, characterized in that, The heating process involves heating the filter residue on the filter screen involved in the solid-liquid separation process or heating the washed product.

4. The manufacturing process for synthesizing high-purity quartz sand by liquid-phase hydrolysis of silicon tetrachloride according to claim 1 or 3, characterized in that, The driving mechanism includes a drive motor, a transmission connected to the drive motor, a gear fixedly mounted on the output shaft of the transmission, a gear ring meshing with the gear, the gear ring being fixedly connected to the outer wall of the furnace body, an annular belt being fixedly mounted on the outer wall of the furnace body, and a support roller adapted to the belt.

5. The manufacturing process for synthesizing high-purity quartz sand by liquid-phase hydrolysis of silicon tetrachloride according to claim 4, characterized in that, After washing, solid-liquid separation, and drying, the hydrolysis products are sent to the feed inlet of the calcining furnace. The furnace body is heated by a direct-fired heating port. After entering the furnace body, the material is conveyed simultaneously with the furnace rotation and the inclined furnace body. The material is discharged after reaching the discharge port.

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