Production process and device for preparing high-purity silica sol from by-products of polysilicon broken powder

Abstract

The present invention relates to the technical field of silica sol preparation, and provides a production process and device for preparing high-purity silica sol from polysilicon crushing powder by-products. The process includes the following steps: S1, smelting of silicon powder; S2, fine crushing of smelted silicon blocks; S3, preparation of silica sol. The device includes an intermediate frequency furnace for smelting polysilicon crushing powder by-products; a mold for cooling the silicon separated by smelting and forming silicon blocks; a crushing device for finely crushing the above-mentioned silicon blocks to form silicon powder; a reaction kettle for the reaction of silicon powder; a plate and frame filter press and a tubular centrifuge for separating and concentrating to form high-purity silica sol. The beneficial effects of this application: In this application, the polysilicon crushing powder by-products are smelted by an intermediate frequency furnace to obtain high-purity silicon blocks. The high-purity silicon blocks are crushed into high-purity silicon powder with the particle size required for preparing silica sol of different particle sizes, which is used to prepare high-purity silica sol, reducing the production cost and enabling large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of nano - scale silica sol synthesis. Specifically, it relates to a production process and device for preparing high - purity silica sol from the by - product of polysilicon crushing powder. Background Art

[0002] Silica sol is a colloidal solution formed by the uniform dispersion of amorphous silica in water. Because of its characteristics such as controllable particle size, moderate hardness, low viscosity, low adhesiveness, and easy cleaning after polishing, it is widely used in CMP polishing. As the main component of CMP polishing liquid, its purity determines the quality of CMP polishing liquid. And the polishing of semiconductor silicon wafers, fine polishing of silicon carbide substrates, and conductive layers in semiconductor processes have higher requirements for purity. Metal ions such as Na, Fe, Al, Ca, Mg, Cu, Pb, etc. will cause defects on the surface of the wafer, thus affecting the performance of semiconductors.

[0003] Currently, the processes for preparing silica sol mainly include silane hydrolysis method, elemental silicon hydrolysis method, and ion exchange method. Using organosilane as the silicon source and water and alcohol as solvents, high - purity silica sol with extremely low metal impurity content can be obtained. However, this method has high raw material prices, high safety risks in industrial production, and great industrialization difficulties. Therefore, industrial production is still basically monopolized by Japanese Fuso. The ion exchange method using water glass as the raw material is not suitable for preparing high - purity silica sol because the content of iron, aluminum, etc. in the raw material itself is relatively high and it is difficult to remove in subsequent processing.

[0004] The silicon powder hydrolysis process uses elemental silicon as the raw material and mainly uses strong alkalis such as NaOH and KOH as catalysts to obtain silica sol. The purity of the raw material silicon powder determines the purity of the silica sol. Currently, the content of metal impurities such as Fe, Al, Ca, Mg, etc. in ordinary industrial silicon powder is relatively high, and directly using high - purity polysilicon has an extremely high price. Therefore, developing a high - purity silicon powder raw material with low cost for preparing high - purity silica sol meets the market demand and has important market value.

[0005] Polysilicon is an important electronic material, widely used in the semiconductor industry and the photovoltaic industry. It can be divided into electronic - grade polysilicon and solar - grade polysilicon according to purity. Currently, the silicon materials produced by polysilicon production enterprises are all rod - shaped polysilicon with a diameter of 300 - 500 mm. In the subsequent application process of polysilicon, whether it is polycrystalline ingot casting or single - crystal pulling, polysilicon needs to be broken into blocks or smaller particles. In the process of polysilicon crushing, a fine powder by - product with a particle size below 3 mm will be generated. This part of the powder has a relatively fine particle size, different morphologies, and uneven particle size, but it has high purity. It has a huge price advantage compared with the genuine polysilicon. How to make good use of this powder to prepare silica sol with high purity and uniform particle size is of extremely important significance. Summary of the Invention

[0006] This application proposes a production process and device for preparing high-purity silica sol from by-products of polysilicon broken powder, which is suitable for mass production of silica sol. In this application, the by-products of polysilicon broken powder are smelted by an intermediate frequency furnace to obtain high-purity silicon blocks, and the high-purity silicon blocks are crushed into high-purity silicon powder with the particle sizes required for preparing silica sol with different particle sizes, which is used to prepare high-purity silica sol. In the present invention, the cost increase of smelting the by-products of polysilicon broken powder by an intermediate frequency furnace is relatively low, far lower than the price of genuine polysilicon, and the crushed particle size after smelting is controllable, which is more conducive to preparing silica sol with uniform particle size. The conversion rate of the crushed silicon powder after smelting is also greatly improved compared with directly using the by-product powder.

[0007] For this reason, in the first aspect of this application, a production device for preparing high-purity silica sol from by-products of polysilicon broken powder is provided, including:

[0008] An intermediate frequency furnace for smelting by-products of polysilicon broken powder;

[0009] A mold for cooling the silicon separated by smelting and forming silicon blocks;

[0010] A crushing device for finely crushing the above-mentioned silicon blocks to form silicon powder;

[0011] A reaction kettle for the reaction of silicon powder;

[0012] A plate and frame filter press and a tubular centrifuge for separating and concentrating to form high-purity silica sol.

[0013] By adopting the above technical solutions: the above device constitutes a production system, which can realize the above production process. After smelting by an intermediate frequency furnace, the conversion rate of the product is significantly improved. After smelting and crushing, the particle size of the silicon powder is controllable. By controlling different process parameters, silica sol products with different particle sizes can be prepared, which greatly meets the requirements of different polishing liquids for the particle size of silica sol. Moreover, the process is controllable, the stability of the product is good, and the conversion rate is high.

[0014] Optionally, the interior of the crushing device includes a housing, at the upper end of which there is a crushing pair of rollers, and inside which there is a fine crushing and screening integrated mechanism.

[0015] By adopting the above technical solutions: the fine crushing and screening integrated mechanism can first pre-crush large silicon blocks and then finely crush them to meet the particle size requirements of different products.

[0016] Optionally, the fine crushing and screening integrated mechanism includes a driving mechanism arranged at the lower part of the housing, a crushing knife is connected to the output shaft of the driving mechanism, the crushing knife is located below the crushing pair of rollers, and a bowl-shaped screening mesh plate is also arranged on the output shaft.

[0017] By adopting the above technical solution: The silicon blocks pre-crushed by the crushing rolls form granular shapes. Under the high-speed rotation of the crushing blades, fine crushing can be carried out. At the same time, when the bowl-shaped screening mesh plate rotates, the particles are thrown to the side of the bowl-shaped screening mesh plate by centrifugal force. The qualified powder particles are screened out, and the unqualified powder particles can be further crushed by the crushing blades through the flipping of the bowl-shaped screening mesh plate until they are screened out.

[0018] Optionally, the reaction kettle includes a main body, and a fine mixing mechanism is provided inside the main body. The fine mixing mechanism includes a plurality of swing rods connected to the inner wall of the main body through a torsion shaft. A stirring shaft is provided inside the main body, and a number of L-shaped stirring rods are provided on the stirring shaft. The lower end of the L-shaped stirring rod is lapped on the swing rod.

[0019] By adopting the above technical solution: When the stirring shaft rotates, the L-shaped stirring rod can rotate for stirring, and at the same time, it can touch the swing rod to swing left and right for more sufficient stirring and mixing, improving the reaction efficiency.

[0020] The second aspect of the present application provides a process for preparing high-purity silica sol by using the above production device for preparing high-purity silica sol from the by-products of polysilicon crushing powder, including the following steps:

[0021] S1. Smelting of silicon powder: Add the by-products of polysilicon crushing powder into the medium-frequency furnace, add a set amount of flux, start the medium-frequency furnace to heat to the set temperature to melt the by-products of polysilicon crushing powder, carry out smelting for a set time, separate the by-products of polysilicon crushing powder from the impurities inside, and pour the separated silicon into a mold to cool and break it into pieces;

[0022] S2. Fine crushing of the smelted silicon blocks: Crush the silicon blocks smelted in the medium-frequency furnace into silicon powder with a set particle size for the production of silica sol;

[0023] S3. Preparation of silica sol: Add a set amount of high-purity water into the reaction kettle, heat to the set temperature A, start the stirring of the reaction kettle, add a set amount of catalyst into the reaction kettle, add the silicon powder prepared in the above step S2 into the reaction kettle according to the set proportion, control the reaction temperature B through spraying, shell-and-tube cooler, and circulation of the reaction kettle jacket, react for a certain time, and discharge the material for solid-liquid separation and concentration.

[0024] By adopting the above technical solution: The by-products of polysilicon crushing powder are smelted in a medium-frequency furnace to obtain high-purity silicon blocks, and the high-purity silicon blocks are crushed into high-purity silicon powder with the particle size required for preparing silica sol of different particle sizes, which is used to prepare high-purity silica sol, reducing the production cost and enabling large-scale production.

[0025] Optionally, in the step S1, Si in the by-products of polysilicon crushing powder ≥ 99%.

[0026] Optionally, the smelting set temperature of the polysilicon crushed powder by-product is 1650 - 1750 °C, the weight ratio of the flux to the polysilicon crushed powder by-product is 1:80 - 100, and the set smelting time of the polysilicon crushed powder by-product is 1 - 2 h.

[0027] Optionally, the material of the crushing equipment in step S2 is tungsten carbide, and the set particle size of the silicon powder crushing is 30 - 325 mesh.

[0028] Optionally, the set particle sizes of the silicon powder crushing are two types: 30 - 100 mesh and 200 - 325 mesh.

[0029] Optionally, the resistivity of the high-purity water used in step S3 is 18.2 MΩ.cm, the catalyst used is of superior purity, the type of the catalyst is potassium hydroxide or ammonia water, the temperature A is 40 - 95 °C, the temperature B is 85 - 100 °C, the weight ratio of the silicon powder to the high-purity water is 1:0.8 - 2.5, and the equipment for solid-liquid separation is a plate-and-frame filter press and a tubular centrifuge.

[0030] The working principle and beneficial effects of this application are as follows:

[0031] 1. In this application, the polysilicon crushed powder by-product is smelted by an intermediate frequency furnace to obtain high-purity silicon blocks, and the high-purity silicon blocks are crushed into high-purity silicon powder with the particle sizes required for preparing silica sols of different particle sizes, which is used to prepare high-purity silica sols, reducing the production cost and enabling large-scale production.

[0032] 2. The above devices of this application form a production system, which can realize the above production process. After smelting by an intermediate frequency furnace, the conversion rate of the product is significantly improved. After smelting and crushing, the particle size of the silicon powder is controllable. By controlling different process parameters, silica sol products with different particle sizes can be prepared, greatly meeting the requirements of different polishing fluids for the particle size of silica sol, and the process is controllable, the product has good stability and high conversion rate.

[0033] 3. In this application, the silicon blocks pre-crushed by the crushing rollers form granular shapes. Under the high-speed rotation of the crushing blades, fine crushing can be carried out. At the same time, when the bowl-shaped screening mesh plate rotates, the particles are thrown to the side of the bowl-shaped screening mesh plate by centrifugal force. The qualified powder particles are screened out, and the unqualified powder particles can be further crushed by the crushing knife after the bowl-shaped screening mesh plate is turned over until they are screened out, and the particle size is controllable.

[0034] 4. When the stirring shaft rotates in this application, the L-shaped stirring rod can rotate for stirring, and at the same time, it can touch the swing rod to swing left and right for more sufficient stirring and mixing, improving the reaction efficiency. Description of the Drawings

[0035] The present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0036] Figure 1 is the overall process flow framework diagram of the present application;

[0037] Figure 2 is the TEM image of the particle size of the silica sol product in Example 1;

[0038] Figure 3 is the TEM image of the particle size of the silica sol product in Example 2;

[0039] Figure 4 is the DLS image of the particle size of the silica sol product in Example 2;

[0040] Figure 5 is the picture of the by-products of polysilicon crushing without smelting;

[0041] Figure 6 is the picture of the unreacted silicon powder directly prepared from the by-products of polysilicon crushing without smelting;

[0042] Figure 7 is the picture of the 30-100 mesh high-purity silicon powder obtained by smelting and crushing the by-products of polysilicon crushing;

[0043] Figure 8 is the overall structure diagram of the device in the embodiment of the present application;

[0044] Figure 9 is the structural schematic diagram of the crushing equipment in the embodiment of the present application;

[0045] Figure 10 is the structural schematic diagram of the reaction kettle implemented in the present application.

[0046] In the figure: 100, intermediate frequency furnace; 200, mold; 300, crushing equipment; 310, housing; 320, crushing counter-rolls; 330, drive mechanism; 340, crushing knife; 350, bowl-shaped screening mesh plate; 400, reaction kettle; 410, body; 420, torsion shaft; 430, swing rod; 440, stirring shaft; 450, L-shaped stirring rod; 460, temperature control layer; 500, plate and frame filter press; 600, tubular centrifuge. Specific Embodiments

[0047] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0048] As Figure 1And Figure 10 As shown, this embodiment provides a production process for preparing high-purity silica sol from the by-products of polysilicon crushed powder, including the following steps:

[0049] S1. Smelting of silicon powder: Add the by-products of polysilicon crushed powder into the intermediate frequency furnace 100, and add a set amount of flux. The flux used is boric acid (H3BO3) to reduce the melting point of the by-products of polysilicon crushed powder, improve fluidity, and facilitate processing. Start the intermediate frequency furnace 100 to heat to the set temperature to melt the by-products of polysilicon crushed powder, conduct smelting for a set time, separate the polysilicon crushed powder by-products from the impurities inside, and pour the separated silicon into the mold 200 to cool and break it into pieces;

[0050] S2. Fine crushing of the smelted silicon blocks: Crush the silicon blocks smelted by the intermediate frequency furnace 100 into silicon powder with a set particle size using the crushing equipment 300 for the production of silica sol;

[0051] S3. Preparation of silica sol: Add a set amount of high-purity water into the reaction kettle 400, heat to the set temperature A, start the stirring of the reaction kettle 400, add a set amount of catalyst into the reaction kettle 400, add the silicon powder prepared in the above step S2 into the reaction kettle 400 according to the set proportion, control the reaction temperature B through spraying, shell-and-tube cooler, and the jacket circulation of the reaction kettle 400, react for a certain time, and discharge the material for solid-liquid separation and concentration.

[0052] The basic principle of this embodiment: Smelt the by-products of polysilicon crushed powder through the intermediate frequency furnace 100 to obtain high-purity silicon blocks, crush the high-purity silicon blocks into high-purity silicon powder with the particle size required for preparing silica sol of different particle sizes, and use it to prepare high-purity silica sol, which reduces the production cost and can be produced in large quantities.

[0053] Among them, in the step S1, Si in the by-products of polysilicon crushed powder is ≥99%.

[0054] Among them, in the smelting of the by-products of polysilicon crushed powder, the set temperature is 1650 - 1750 °C, the weight ratio of the flux to the by-products of polysilicon crushed powder is 1:80 - 100, and the set smelting time of the by-products of polysilicon crushed powder is 1 - 2 h.

[0055] Among them, in the step S2, the material of the crushing equipment 300 is tungsten carbide, and the set particle size of the silicon powder crushing is 30 - 325 mesh.

[0056] Among them, the set particle size of the silicon powder crushing is two particle size types of 30 - 100 mesh and 200 - 325 mesh.

[0057] Among them, the resistivity of the high-purity water used in the step S3 is 18.2 MΩ.cm, the catalyst used is of superior grade purity, the types of catalysts are potassium hydroxide or ammonia water, the temperature A is 40 - 95 °C, the temperature B is 85 - 100 °C, the weight ratio of silicon powder to high-purity water is 1:1.5 - 2.5, and the equipment for solid-liquid separation is a plate-and-frame filter press 500 and a tubular centrifuge 600.

[0058] More specifically, the following are two specific implementation manners: Example

[0059] Add the by-product of polysilicon crushed powder into the medium-frequency furnace 100, add a certain amount of flux, start the medium-frequency furnace 100, heat it to 1700 °C by induction heating technology to melt the silicon powder. At high temperature, the silicon powder is separated from the impurities inside. Pour the separated silicon into the mold 200 to cool and break it into pieces. Crush the silicon blocks obtained from smelting into 200 - 325 mesh. Add high-purity water to prepare a slurry for standby, and the ratio of the silicon powder to the high-purity water used is 1:2.

[0060] Add 5000 parts of high-purity water to the reaction kettle 400, heat it to 50 - 60 °C, start the stirring of the reaction kettle 400, add 60 parts of superior-grade pure potassium hydroxide to the reaction kettle 400, stir for 10 - 20 min, add the prepared silicon powder slurry into the reaction kettle 400 at a frequency of 30 HZ, and the silicon powder added to the reaction kettle 400 is calculated as 450 parts in terms of dry silicon powder. Turn on the cooling water and spray device, control the reaction temperature between 90 - 95 °C, react for 5 h, discharge the material for plate-and-frame filtration and centrifuge centrifugation, and concentrate to a content of 20%. The silica sol prepared by this reaction is a potassium-type silica sol with a small particle size, the product particle size is 6 nm, and other heavy metals are < 100 ppb. The products of this process can be used for medium polishing of silicon wafers and chips. The products are as Figure 2 shown. Example

[0061] Add the by-product powder crushed from polysilicon into the medium-frequency furnace 100, add a certain amount of flux, start the medium-frequency furnace 100, heat it to 1700 °C by induction heating technology to melt the silicon powder. At high temperature, the silicon powder is separated from the impurities inside. Pour the separated silicon into the mold 200 to cool and break it into pieces. Crush the silicon blocks obtained from smelting into 30 - 100 mesh, add 20 parts of superior-grade pure ammonia water to 180 parts of high-purity water, and prepare a dilute solution A of ammonia water.

[0062] Add 3000 parts of high-purity water and 20 parts of super-grade pure ammonia water into the reactor 400, heat to 90 - 92 °C, start the stirring of the reactor 400, add 280 parts of silicon powder, react at a constant temperature of 95 ± 2 °C for 2 h, uniformly dropwise add A, and the dropping time is 30 h. After dropping the ammonia water, continue to react for 10 h, discharge the material, carry out plate-and-frame pressure filtration, centrifugation, and concentrate to form 40% high-purity ammonia-type silica sol. The silica sol prepared by this reaction is high-purity ammonia-type silica sol, the product particle size is about 50 nm, the particle size distribution is uniform, the alkali metal in the silica sol obtained by this reaction is < 300 ppb, the heavy metal is < 100 ppb, and the purity can reach the same level as that of Japanese Fuso, and it can be used for the fine polishing of semiconductors. Products such as Figure 3 and Figure 4 shown.

[0063] The particle sizes of the by-products of polysilicon crushed powder are uneven and the shapes are non-uniform, such as Figure 5 . Directly using the by-products of polysilicon crushed powder to produce silica sol, the particle sizes of the obtained silica sol are uneven, and the stability between batches is poor, which cannot meet the normal market demand, and the conversion rate of the product is low. After the reaction, there will be a large amount of unreacted flaky powder, such as Figure 6 , which is speculated to be related to the crystal structure. The present invention can effectively control the particle size of the required high-purity silicon powder, and the purity of the silicon powder can be further improved through smelting technology. After smelting, the conversion rate of the product of the silicon powder is significantly improved, and after smelting and crushing, the particle size of the silicon powder is controllable, such as Figure 7 , with high purity. Different particle size silica sol products can be prepared through different processes, which greatly meets the requirements of different polishing liquids for the particle size of silica sol, and the process is controllable, the product has good stability, and the conversion rate is high.

[0064] Such as Figures 8 - 10 , this application provides a production device for preparing high-purity silica sol from by-products of polysilicon crushed powder, including:

[0065] The intermediate frequency furnace 100 is used for smelting the by-product powder crushed from polysilicon;

[0066] The mold 200 is used for cooling the silicon separated by smelting and forming silicon blocks;

[0067] The crushing equipment 300 is used for finely crushing the above-mentioned silicon blocks to form silicon powder;

[0068] The reactor 400 is used for the reaction of silicon powder;

[0069] The plate-and-frame filter press 500 and the tubular centrifuge 600 are used for separating and concentrating to form high-purity silica sol.

[0070] Overall principle of the above device: The above device constitutes a production system, which can implement the above production process. After smelting by the intermediate frequency furnace 100, the conversion rate of the product is significantly improved. After smelting and crushing, the particle size of the silicon powder is controllable. Different particle sizes of silica sol products can be prepared by controlling different process parameters, which greatly meets the requirements of different polishing liquids for the particle size of silica sol. Moreover, the process is controllable, the product has good stability and high conversion rate.

[0071] The crushing device 300 therein includes a housing 310. At the upper end inside it, there is a crushing pair roll 320. Inside it, there is a fine crushing and screening integrated mechanism. The fine crushing and screening integrated mechanism can first pre-crush large silicon blocks and then perform fine crushing to meet the particle size requirements of different products.

[0072] The fine crushing and screening integrated mechanism includes a driving mechanism 330 arranged at the lower part of the housing 310. A crushing knife 340 is connected to the output shaft of the driving mechanism 330. The crushing knife 340 is located below the crushing pair roll 320. It also includes a bowl-shaped screening mesh plate 350 arranged on the output shaft. The silicon blocks pre-crushed by the crushing pair roll form granular shapes. Under the high-speed rotation of the crushing knife 340 blades, fine crushing can be carried out. At the same time, when the bowl-shaped screening mesh plate 350 rotates, the particles are thrown to the side of the bowl-shaped screening mesh plate 350 by centrifugal force. The powder particles that meet the requirements are screened out. The powder particles that do not meet the requirements can be further crushed by the crushing knife 340 after the bowl-shaped screening mesh plate 350 is turned over until they are screened out.

[0073] The reaction kettle 400 therein includes a main body 410. Inside the main body 410, there is a fine mixing mechanism. The fine mixing mechanism includes a plurality of swing rods 430 connected to the inner wall of the main body 410 through a torsion shaft 420. Inside the main body 410, there is a stirring shaft 440. A number of L-shaped stirring rods 450 are arranged on the stirring shaft 440. The lower end of the L-shaped stirring rod 450 is lapped on the swing rod 430. When the stirring shaft 440 rotates, the L-shaped stirring rods 450 can rotate for stirring, and at the same time, they can touch the swing rods 430 to swing left and right for more sufficient stirring and mixing, improving the reaction efficiency. On the outer peripheral side of the main body 410, there is a temperature control layer 460, and a heating medium circulates inside.

[0074] The above is only the preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A production device for preparing high-purity silica sol from by-products of polysilicon broken powder, characterized in that, Comprising: An intermediate frequency furnace (100) for smelting the by-product of polysilicon crushed powder; A mold (200) for cooling the silicon separated by smelting and forming silicon blocks; A crushing device (300) for finely crushing the above-mentioned silicon blocks to form silicon powder; A reaction kettle (400) for the reaction of silicon powder; A plate and frame filter press (500) and a tubular centrifuge (600) for separating and concentrating to form high-purity silica sol; The crushing device (300) includes a housing (310). At the upper end inside the housing (310), there is a crushing pair roller (320), and an integrated mechanism for fine crushing and screening is arranged inside it; The integrated mechanism for fine crushing and screening includes a driving mechanism (330) arranged at the lower part of the housing (310). A crushing knife (340) is connected to the output shaft of the driving mechanism (330). The crushing knife (340) is located below the crushing pair roller (320). It also includes a bowl-shaped screening mesh plate (350) arranged on the output shaft. After being pre-crushed by the crushing pair roller (320) to form granular shape, it is finely crushed under the high-speed rotation of the crushing knife (340). At the same time, when the bowl-shaped screening mesh plate (350) rotates, the particles are thrown to the side of the bowl-shaped screening mesh plate (350) by centrifugal force. The powder particles that meet the requirements are screened out, and the powder particles that do not meet the requirements are further crushed by the crushing knife (340) after the bowl-shaped screening mesh plate (350) is turned over until they are screened out; The reaction kettle (400) includes a main body (410). An accurate mixing mechanism is arranged inside the main body (410). The accurate mixing mechanism includes a plurality of swing rods (430) connected to the inner wall of the main body (410) through a torsion shaft (420). A stirring shaft (440) is arranged inside the main body (410). A number of L-shaped stirring rods (450) are arranged on the stirring shaft (440). The lower end of the L-shaped stirring rod (450) is lapped on the swing rod (430). When the stirring shaft (440) rotates, the L-shaped stirring rod (450) rotates to stir, and at the same time, it touches the swing rod (430) to swing left and right for sufficient stirring and mixing.

2. A production process for preparing high-purity silica sol using the production device for preparing high-purity silica sol from the by-product of polysilicon crushed powder described in claim 1, characterized in that, Including the following steps: S1. Smelting of silicon powder: Add the by-product of polysilicon crushed powder into the intermediate frequency furnace (100), add a set amount of flux, start the intermediate frequency furnace (100) to heat to the set temperature to melt the by-product of polysilicon crushed powder, carry out smelting for a set time, separate the by-product of polysilicon crushed powder from the impurities inside it, and pour the separated silicon into the mold (200) to cool and break it into silicon blocks; S2. Fine crushing of the smelted silicon blocks: Crush the silicon blocks smelted by the intermediate frequency furnace (100) into silicon powder with a set particle size using the crushing device (300) for the production of silica sol; S3. Preparation of silica sol: Add a set amount of high-purity water into the reaction kettle (400), heat it to the set temperature A, start the stirring of the reaction kettle (400), add a set amount of catalyst into the reaction kettle (400), add the silicon powder prepared in the above step S2 into the reaction kettle (400) according to the set proportion, control the reaction temperature B through spraying, shell-and-tube cooler, and reaction kettle (400), react for a certain period of time, and discharge the material for solid-liquid separation and concentration.

3. The production process for preparing high-purity silica sol using the production device for preparing high-purity silica sol from polysilicon crushing powder by-products according to claim 2, characterized in that, In the step S1, Si in the polysilicon crushed powder by-product is ≥99%.

4. The production process of preparing high-purity silica sol by using the production device for preparing high-purity silica sol from the by-products of polysilicon crushed powder according to claim 2, characterized in that, The smelting set temperature of the polysilicon crushed powder by-product is 1650 - 1750 °C, the weight ratio of the flux to the polysilicon crushed powder by-product is 1:80 - 100, and the smelting set time of the polysilicon crushed powder by-product is 1 - 2 h.

5. The production process of preparing high-purity silica sol by using the production device for preparing high-purity silica sol from the by-products of polysilicon broken powder according to claim 2, characterized in that, In the step S2, the material of the crushing equipment (300) is tungsten carbide, and the set particle size of silicon powder crushing is 30 - 325 mesh.

6. The production process for preparing high-purity silica sol by using the production device for preparing high-purity silica sol from polysilicon crushed powder by-products according to claim 5, characterized in that, The set particle size of silicon powder crushing is two particle size types of 30 - 100 mesh and 200 - 325 mesh.

7. The production process for preparing high-purity silica sol by using the production device for preparing high-purity silica sol from by-products of polysilicon crushed powder according to claim 2, characterized in that, In the step S3, the resistivity of the high-purity water used is 18.2 MΩ·cm, the catalyst used is of superior grade purity, the types of the catalyst are potassium hydroxide or ammonia water, the temperature A is 40 - 95 °C, the temperature B is 85 - 100 °C, the weight ratio of the silicon powder to the high-purity water is 1:0.8 - 2.5, and the equipment for solid-liquid separation is a plate-and-frame filter press (500) and a tubular centrifuge (600).

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