Low-carbon technology for preparing nanometer silicon mortar based on photovoltaic silicon sludge one-step method
By using a one-step process to directly utilize the moisture in photovoltaic silicon sludge through wet mixing and centrifugal classification, a closed-loop cycle is formed, which solves the problems of high energy consumption and dust pollution in the resource utilization of photovoltaic silicon sludge and realizes the preparation of low-carbon and high-efficiency nano-silica slurry.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-30
- Publication Date
- 2026-04-03
AI Technical Summary
Existing photovoltaic silicon sludge resource utilization technologies suffer from high energy consumption, severe dust pollution, easy product deterioration, high cost of purchased dry powder nano-SiO2, and low resource utilization rate, making it difficult to meet the green and low-carbon development needs of the photovoltaic industry.
A one-step process is adopted, which combines wet stirring milling and centrifugal grading to directly utilize the moisture of photovoltaic silicon sludge as a medium to grind and grade it, forming a closed-loop circulation system to prepare nano-silica slurry.
Significantly reduces energy consumption, improves raw material utilization, avoids dust pollution, ensures precise control of product particle size, reduces raw material costs, and achieves efficient resource utilization of silicon resources.
Smart Images
Figure CN121778737A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of resource recycling technology, and specifically relates to a low-carbon process for preparing nano-silica slurry based on a one-step method of photovoltaic silicon sludge. Background Technology
[0002] With the rapid development of the photovoltaic industry, the amount of photovoltaic silicon sludge waste generated during the production of photovoltaic silicon materials has increased significantly. The main components of this sludge are elemental silicon and a small amount of silicon oxide, with a natural water content of about 40%. Direct landfilling or incineration not only wastes silicon resources but also causes environmental pollution. Therefore, its resource utilization has become a key issue that the industry urgently needs to address.
[0003] Currently, the resource utilization of photovoltaic silicon sludge or the preparation of nano-silicon materials mainly relies on two technical routes: one is the traditional two-step "drying-grinding" process, and the other is purchasing dry powder nano-SiO2 as raw material for subsequent processing. Existing patents propose drying the photovoltaic silicon sludge to a moisture content of less than 5% before grinding it into silicon powder using dry ball milling equipment. While this achieves resource recovery, the drying process consumes a large amount of heat energy, the grinding process easily generates silicon dust pollution, and the product particle size distribution is uneven, requiring additional classification treatment. Other patents use purchased dry powder nano-SiO2 as raw material, adding water to form a slurry for subsequent processing. However, the production and transportation costs of dry powder nano-SiO2 are high, the slurry preparation process easily generates dust, and it cannot achieve the resource utilization of photovoltaic silicon sludge waste, which is inconsistent with the concept of circular economy development.
[0004] The traditional "drying-grinding" process requires removing 40% of the moisture from photovoltaic silicon sludge, resulting in extremely high energy consumption. Furthermore, the hard impact of dry grinding can easily lead to oxidation and deterioration of silicon particles. The external purchase of dry powder has inherent drawbacks such as high cost, poor environmental performance, and low resource utilization. Existing technologies cannot meet the needs of the photovoltaic industry for green and low-carbon development. Summary of the Invention
[0005] The purpose of this invention is to provide a low-carbon process for preparing nano-silica slurry based on a one-step photovoltaic silicon sludge method, addressing the above-mentioned shortcomings. This process solves the problems of high energy consumption, severe dust pollution, and easy product deterioration in the traditional "drying-grinding" process, as well as the high cost and low resource utilization of the purchased dry powder nano-SiO2 route.
[0006] This invention is achieved through the following scheme: A low-carbon process for preparing nano-silica slurry in one step based on photovoltaic silicon sludge includes the following steps: Step S1, Raw material preparation: Select photovoltaic silicon sludge as raw material. No drying or grinding pretreatment is required. It can be used directly as raw material slurry to be treated. Step S2, Wet stirred mill grinding: The raw material slurry is fed into the grinding device for grinding; Step S3, Centrifugal Classification and Screening: The ground mixture slurry is fed into a centrifugal classification device. The separated coarse particles are returned to the wet stirred mill for re-grinding, and the fine particles flow out to obtain nano silica slurry. Step S4, Closed-loop circulation: Through grinding-grading linkage, coarse particles are circulated and ground to form a "slurry-slurry" closed-loop system of "raw material slurry-mixed material slurry-nano silica slurry".
[0007] In step S1, the water mass fraction of the photovoltaic silicon sludge is 40%, and the main components of the sludge are silicon elemental with a mass fraction of ≥85% and silicon oxide with a mass fraction of ≤15%.
[0008] In step S2, the raw material slurry is fed into a closed wet stirred mill, using the water contained in the raw material itself as the grinding and dispersing medium, and adding zirconia beads as the grinding medium.
[0009] In step S2, specifically, the grinding media has a particle size of 0.5-2 mm, the mass ratio of grinding media to raw material slurry is 5-8:1, the stirring speed is set to 800-1200 r / min, and the grinding time is 30-60 min.
[0010] During the grinding process, the slurry temperature is controlled between 25-40℃.
[0011] In step S3, the centrifugal grading equipment is a disc centrifuge or a tubular centrifuge.
[0012] In step S3, the centrifugal speed is set to 5000-8000 r / min, the feed rate is 10-20 L / h, and the slurry concentration is 20-30 wt%.
[0013] This solution also provides a specific low-carbon process for preparing nano-silica slurry in one step based on photovoltaic silicon sludge, the specific steps of which include: Step S1, Raw material preparation: Select photovoltaic silicon sludge with a water content of 40% by mass as raw material, of which silicon elemental mass fraction is 88% and silicon oxide mass fraction is 12%, and use it directly as raw material slurry; Step S2, wet stirred mill grinding: The raw material slurry is fed into a closed wet stirred mill, zirconia beads with a particle size of 1mm are added, the mass ratio of grinding media to raw material slurry is 6:1, the stirring speed is set to 1000r / min, the grinding time is 45min, and the slurry temperature is controlled at 30℃ by the cooling system. Step S3, centrifugal classification and screening: The mixed slurry is fed into a disc centrifugal classifier, the centrifugal speed is set to 6500 r / min, the feed rate is 15 L / h, and the slurry concentration is 25 wt%. The separated coarse particles are returned to the wet stirred mill for re-grinding, and the fine particles that flow out are nano silica slurry. Step S4, Closed-loop circulation: Continuously run the grinding-grading linkage system to achieve the recycling of coarse particles.
[0014] This solution also provides a specific low-carbon process for preparing nano-silica slurry in one step based on photovoltaic silicon sludge, the specific steps of which include: Step S1, Raw material preparation: Select photovoltaic silicon sludge with a water content of 40% by mass as raw material, of which silicon elemental mass fraction is 85% and silicon oxide mass fraction is 15%, and use it directly as raw material slurry; Step S2, wet stirred mill grinding: The raw material slurry is fed into a closed wet stirred mill, zirconia beads with a particle size of 0.8mm are added, the mass ratio of grinding media to raw material slurry is 5:1, the stirring speed is set to 800r / min, the grinding time is 60min, and the slurry temperature is controlled at 25℃ by the cooling system. Step S3, centrifugal classification and screening: The mixed slurry is fed into a tubular centrifugal classification device, the centrifugal speed is set to 5000 r / min, the feed rate is 10 L / h, and the slurry concentration is 20 wt%. The separated coarse particles are returned to the wet stirred mill for re-grinding, and the fine particles that flow out are nano silica slurry. Step S4, Closed-loop circulation: Continuously run the grinding-grading linkage system to achieve the recycling of coarse particles.
[0015] This solution also provides a specific low-carbon process for preparing nano-silica slurry in one step based on photovoltaic silicon sludge, the specific steps of which include: Step S1, Raw material preparation: Select photovoltaic silicon sludge with a water content of 40% by mass as raw material, of which silicon elemental mass fraction is 90% and silicon oxide mass fraction is 10%, and use it directly as raw material slurry; Step S2, wet stirred mill grinding: The raw material slurry is fed into a closed wet stirred mill, zirconia beads with a particle size of 2mm are added, the mass ratio of grinding media to raw material slurry is 8:1, the stirring speed is set to 1200r / min, the grinding time is 30min, and the slurry temperature is controlled at 40℃ through the cooling system. Step S3, centrifugal classification and screening: The mixed slurry is fed into a disc centrifugal classifier, the centrifugal speed is set to 8000 r / min, the feed rate is 20 L / h, and the slurry concentration is 30 wt%. The separated coarse particles are returned to the wet stirred mill for re-grinding, and the fine particles that flow out are nano silica fume slurry. Step S4, Closed-loop circulation: Continuously run the grinding-grading linkage system to achieve the recycling of coarse particles.
[0016] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This solution eliminates the drying-grinding step of the traditional process and makes full use of the water content of photovoltaic silicon sludge itself, reducing energy consumption by 60% compared with the traditional process and significantly reducing production costs; the entire process is carried out in a closed environment, wet grinding has no dust pollution, and the closed-loop system avoids material leakage, which is in line with the concept of green production.
[0017] 2. This solution uses a closed-loop "grinding-grading" process to re-grind the separated coarse particles, increasing the raw material utilization rate to over 95% and avoiding waste of silicon resources. The particle size of the product, nano-silica slurry, is precisely controllable, with d50 stably controlled at around 200nm. It can be directly used in subsequent slurry processing steps without additional slurry preparation.
[0018] 3. This solution uses photovoltaic silicon sludge waste as raw material to replace purchased dry powder nano-SiO2, significantly reducing raw material costs while realizing the resource utilization of waste and solving the environmental disposal problem of photovoltaic silicon sludge. Silicon powder prepared by traditional processes is easily oxidized during drying and grinding, and has uneven particle size distribution; purchased dry powder slurry preparation easily generates dust, while the product of this invention has stable quality and excellent environmental performance. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the overall process of the present invention. Detailed Implementation
[0020] All features disclosed in this specification, or steps in all methods or processes disclosed herein, may be combined in any way, except for mutually exclusive features and / or steps.
[0021] Any feature disclosed in this specification (including any appended claims and abstract) may be replaced by other equivalent or similar features, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.
[0022] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a predetermined orientation, or be constructed and operated in a predetermined orientation. Therefore, they should not be construed as limitations on this invention.
[0023] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature.
[0024] like Figure 1As shown, the present invention provides a technical solution: A low-carbon process for preparing nano-silica slurry in one step based on photovoltaic silicon sludge includes the following steps: Step S1, Raw material preparation: Select photovoltaic silicon sludge with a water content of 40% by mass as raw material. The main components of this sludge are elemental silicon (mass fraction ≥ 85%) and a small amount of silicon oxide (mass fraction ≤ 15%). No drying or grinding pretreatment is required. It can be used directly as raw material slurry to be processed. Step S2, wet stirred mill grinding: The raw material slurry is fed into a closed wet stirred mill, using the water contained in the raw material itself as the grinding and dispersing medium, and zirconia beads are added as the grinding medium; the particle size of the grinding medium is 0.5-2mm, and the mass ratio of the grinding medium to the raw material slurry is 5-8:1; the stirring speed is set to 800-1200r / min, the grinding time is 30-60min, and the slurry temperature is controlled at 25-40℃ during the grinding process; Step S3, centrifugal classification and screening: The ground mixture slurry is fed into a centrifugal classification device (disc centrifuge or tubular centrifuge), the centrifugal speed is set to 5000-8000 r / min, the feed rate is 10-20 L / h, and the slurry concentration is 20-30 wt%. The separated coarse particles are returned to the wet stirred mill for re-grinding, and the fine particles flow out to obtain nano silica fume slurry. Step S4, Closed-loop circulation: Through grinding-grading linkage, coarse particles are circulated and ground to form a "slurry-slurry" closed-loop system of "raw material slurry-mixed material slurry-nano silica slurry".
[0025] The photovoltaic silicon sludge maintains a stable water content of 40%, requiring no additional water addition or dehydration. Its own moisture content serves as both a grinding and dispersing medium, reducing the probability of particle agglomeration. The closed-loop wet stirred mill avoids dust pollution, and the cooling system prevents high-temperature oxidation of silicon particles. The centrifugal grading equipment accurately screens particle size, ensuring the product is a nano-silica slurry. 50 =200nm; the zirconia bead grinding media has high hardness and good wear resistance, which can improve grinding efficiency.
[0026] The full utilization of the moisture content of the raw materials eliminates the need for drying at the source; wet grinding improves particle crushing efficiency and avoids dust pollution compared to dry grinding; the closed-loop linkage between centrifugal classification and grinding can improve the utilization rate of raw materials and ensure stable product particle size.
[0027] Below 800℃, a variety of refractory and toughening materials, such as magnesium olivine whiskers, wollastonite, wollastonite fibers, and steel fibers, work together to prevent concrete from cracking at high temperatures.
[0028] Magnesium oxide in magnesium slag undergoes a sintering reaction with active silica in mineral admixtures at temperatures above 800℃ to produce high-temperature ceramic phase magnesium olivine. The sintering reaction causes the particles of each component to bond together, forming a relatively dense blocky substance, which prevents concrete from cracking and enhances the strength of concrete after high-temperature treatment.
[0029] Example 1 A low-carbon process for preparing nano-silica slurry from photovoltaic silicon sludge in one step includes the following steps: Step S1, Raw material preparation: Select photovoltaic silicon sludge with a water content of 40% by mass as raw material, of which silicon elemental mass fraction is 88% and silicon oxide mass fraction is 12%, and use it directly as raw material slurry; Step S2, wet stirred mill grinding: The raw material slurry is fed into a closed wet stirred mill, zirconia beads with a particle size of 1mm are added, the mass ratio of grinding media to raw material slurry is 6:1, the stirring speed is set to 1000r / min, the grinding time is 45min, and the slurry temperature is controlled at 30℃ by the cooling system. Step S3, centrifugal classification and screening: The mixed slurry is fed into a disc centrifugal classifier, the centrifugal speed is set to 6500 r / min, the feed rate is 15 L / h, and the slurry concentration is 25 wt%. The separated coarse particles are returned to the wet stirred mill for re-grinding, and the fine particles that flow out are nano silica slurry. Step S4, Closed-loop circulation: Continuously run the grinding-grading linkage system to achieve the recycling of coarse particles.
[0030] Example 2 A low-carbon process for preparing nano-silica slurry from photovoltaic silicon sludge in one step includes the following steps: Step S1, Raw material preparation: Select photovoltaic silicon sludge with a water content of 40% by mass as raw material, of which silicon elemental mass fraction is 85% and silicon oxide mass fraction is 15%, and use it directly as raw material slurry; Step S2, wet stirred mill grinding: The raw material slurry is fed into a closed wet stirred mill, zirconia beads with a particle size of 0.8mm are added, the mass ratio of grinding media to raw material slurry is 5:1, the stirring speed is set to 800r / min, the grinding time is 60min, and the slurry temperature is controlled at 25℃ by the cooling system. Step S3, centrifugal classification and screening: The mixed slurry is fed into a tubular centrifugal classification device, the centrifugal speed is set to 5000 r / min, the feed rate is 10 L / h, and the slurry concentration is 20 wt%. The separated coarse particles are returned to the wet stirred mill for re-grinding, and the fine particles that flow out are nano silica slurry. Step S4, Closed-loop circulation: Continuously run the grinding-grading linkage system to achieve the recycling of coarse particles.
[0031] Example 3 A low-carbon process for preparing nano-silica slurry from photovoltaic silicon sludge in one step includes the following steps: Step S1, Raw material preparation: Select photovoltaic silicon sludge with a water content of 40% by mass as raw material, of which silicon elemental mass fraction is 90% and silicon oxide mass fraction is 10%, and use it directly as raw material slurry; Step S2, wet stirred mill grinding: The raw material slurry is fed into a closed wet stirred mill, zirconia beads with a particle size of 2mm are added, the mass ratio of grinding media to raw material slurry is 8:1, the stirring speed is set to 1200r / min, the grinding time is 30min, and the slurry temperature is controlled at 40℃ through the cooling system. Step S3, centrifugal classification and screening: The mixed slurry is fed into a disc centrifugal classifier, the centrifugal speed is set to 8000 r / min, the feed rate is 20 L / h, and the slurry concentration is 30 wt%. The separated coarse particles are returned to the wet stirred mill for re-grinding, and the fine particles that flow out are nano silica fume slurry. Step S4, Closed-loop circulation: Continuously run the grinding-grading linkage system to achieve the recycling of coarse particles.
[0032] Compare with Example 1 A process for the resource utilization of photovoltaic silicon sludge (traditional drying-grinding method) includes the following steps: Step S1, Raw material preparation: Select photovoltaic silicon sludge with a water content of 40% by mass as raw material, and dry it at 120℃ for 4 hours until the water content is less than 5%; Step S2, Dry grinding: The dried sludge is fed into a dry ball mill and ground for 60 minutes; Step S3, Grading and Screening: The milled product is fed into a grading device and silicon powder is obtained by screening; the remaining conditions are the same as in Example 1.
[0033] Compare with Example 2 A process for preparing nano-silica slurry (using purchased dry powder) includes the following steps: Step S1, Raw material preparation: Purchase dry powder nano SiO2 and add water to prepare a slurry with a mass fraction of 25%; Step S2, stirring and dispersing: The slurry is fed into a stirring device and stirred for 30 minutes to obtain nano-silica slurry; the remaining conditions are the same as in Example 1.
[0034] Compare with Example 3 A process for preparing nano-silica slurry from photovoltaic silicon sludge (closed-loop without centrifugation and classification) includes the following steps: Step S1, Raw material preparation: Select photovoltaic silicon sludge with a water content of 40% by mass as raw material and use it directly as raw material slurry; Step S2, wet stirred mill grinding: parameters are the same as in Example 1, and the slurry is directly collected as the product after grinding; no centrifugal classification or coarse particle reflux is set.
[0035] The products of each set of examples and control examples were subjected to performance tests. The test indicators included energy consumption, product particle size (d50), raw material utilization rate, and dust emission. The test results are shown in the table below:
[0036] As shown in the table, Examples 1-3, using the process of the present invention, consume only about 40% of the energy of the traditional process (Comparative Example 1), the product particle size is stable at 200nm, the raw material utilization rate is over 95%, and there is no dust emission; Comparative Example 1 has the highest energy consumption, serious dust pollution, and low raw material utilization rate; Although the product particle size of Comparative Example 2 is qualified, the energy consumption is high and it relies on purchased raw materials; Comparative Example 3 has uneven product particle size and low raw material utilization rate due to the lack of centrifugal classification and closed loop, which fully demonstrates the superiority of the process of the present invention.
[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A low-carbon process for preparing nano-silica slurry in one step based on photovoltaic silicon sludge, characterized in that, Includes the following steps: Step S1, Raw material preparation: Select photovoltaic silicon sludge as raw material. No drying or grinding pretreatment is required. It can be used directly as raw material slurry to be treated. Step S2, Wet stirred mill grinding: The raw material slurry is fed into the grinding device for grinding; Step S3, Centrifugal Classification and Screening: The ground mixture slurry is fed into a centrifugal classification device. The separated coarse particles are returned to the wet stirred mill for re-grinding, and the fine particles flow out to obtain nano silica slurry. Step S4, Closed-loop circulation: Through grinding-grading linkage, coarse particles are circulated and ground to form a "slurry-slurry" closed-loop system of "raw material slurry-mixed material slurry-nano silica slurry".
2. The low-carbon process for preparing nano-silica slurry based on photovoltaic silicon sludge in a one-step manner according to claim 1, characterized in that: In step S1, the water mass fraction of the photovoltaic silicon sludge is 40%, and the main components of the sludge are silicon elemental with a mass fraction of ≥85% and silicon oxide with a mass fraction of ≤15%.
3. The low-carbon process for preparing nano-silica slurry based on photovoltaic silicon sludge in a one-step manner according to claim 1, characterized in that: In step S2, the raw material slurry is fed into a closed wet stirred mill, using the water contained in the raw material itself as the grinding and dispersing medium, and adding zirconia beads as the grinding medium.
4. The low-carbon process for preparing nano-silica slurry based on photovoltaic silicon sludge in a one-step manner according to claim 3, characterized in that: In step S2, specifically, the particle size of the grinding media is 0.5-2 mm, and the mass ratio of the grinding media to the raw material slurry is 5-8:1; Set the stirring speed to 800-1200 r / min and the grinding time to 30-60 min.
5. The low-carbon process for preparing nano-silica slurry based on photovoltaic silicon sludge in a one-step manner according to claim 4, characterized in that: During the grinding process, the slurry temperature should be controlled between 25-40℃.
6. A low-carbon process for preparing nano-silica slurry based on a one-step photovoltaic silicon sludge method according to any one of claims 1 to 5, characterized in that: In step S3, the centrifugal grading equipment is a disc centrifuge or a tubular centrifuge.
7. The low-carbon process for preparing nano-silica slurry based on photovoltaic silicon sludge in a one-step manner according to claim 6, characterized in that: In step S3, the centrifugal speed is set to 5000-8000 r / min, the feed rate is 10-20 L / h, and the slurry concentration is 20-30 wt%.
8. The low-carbon process for preparing nano-silica slurry based on photovoltaic silicon sludge in a one-step manner according to claim 1, characterized in that: Step S1, Raw material preparation: Select photovoltaic silicon sludge with a water content of 40% by mass as raw material, of which silicon elemental mass fraction is 88% and silicon oxide mass fraction is 12%, and use it directly as raw material slurry; Step S2, wet stirred mill grinding: The raw material slurry is fed into a closed wet stirred mill, zirconia beads with a particle size of 1mm are added, the mass ratio of grinding media to raw material slurry is 6:1, the stirring speed is set to 1000r / min, the grinding time is 45min, and the slurry temperature is controlled at 30℃ by the cooling system. Step S3, centrifugal classification and screening: The mixed slurry is fed into a disc centrifugal classifier, the centrifugal speed is set to 6500 r / min, the feed rate is 15 L / h, and the slurry concentration is 25 wt%. The separated coarse particles are returned to the wet stirred mill for re-grinding, and the fine particles that flow out are nano silica slurry. Step S4, Closed-loop circulation: Continuously run the grinding-grading linkage system to achieve the recycling of coarse particles.
9. The low-carbon process for preparing nano-silica slurry based on photovoltaic silicon sludge in a one-step manner according to claim 1, characterized in that: Step S1, Raw material preparation: Select photovoltaic silicon sludge with a water content of 40% by mass as raw material, of which silicon elemental mass fraction is 85% and silicon oxide mass fraction is 15%, and use it directly as raw material slurry; Step S2, wet stirred mill grinding: The raw material slurry is fed into a closed wet stirred mill, zirconia beads with a particle size of 0.8mm are added, the mass ratio of grinding media to raw material slurry is 5:1, the stirring speed is set to 800r / min, the grinding time is 60min, and the slurry temperature is controlled at 25℃ by the cooling system. Step S3, centrifugal classification and screening: The mixed slurry is fed into a tubular centrifugal classification device, the centrifugal speed is set to 5000 r / min, the feed rate is 10 L / h, and the slurry concentration is 20 wt%. The separated coarse particles are returned to the wet stirred mill for re-grinding, and the fine particles that flow out are nano silica slurry. Step S4, Closed-loop circulation: Continuously run the grinding-grading linkage system to achieve the recycling of coarse particles.
10. The low-carbon process for preparing nano-silica slurry based on photovoltaic silicon sludge in a one-step manner according to claim 1, characterized in that: Step S1, Raw material preparation: Select photovoltaic silicon sludge with a water content of 40% by mass as raw material, of which silicon elemental mass fraction is 90% and silicon oxide mass fraction is 10%, and use it directly as raw material slurry; Step S2, wet stirred mill grinding: The raw material slurry is fed into a closed wet stirred mill, zirconia beads with a particle size of 2mm are added, the mass ratio of grinding media to raw material slurry is 8:1, the stirring speed is set to 1200r / min, the grinding time is 30min, and the slurry temperature is controlled at 40℃ through the cooling system. Step S3, centrifugal classification and screening: The mixed slurry is fed into a disc centrifugal classifier, the centrifugal speed is set to 8000 r / min, the feed rate is 20 L / h, and the slurry concentration is 30 wt%. The separated coarse particles are returned to the wet stirred mill for re-grinding, and the fine particles that flow out are nano silica fume slurry. Step S4, Closed-loop circulation: Continuously run the grinding-grading linkage system to achieve the recycling of coarse particles.