Grinding and modifying integrated superfine silica powder and preparation method thereof

Abstract

The invention belongs to the technical field of silica powder preparation, and provides grinding and modifying integrated superfine silica powder and a preparation method thereof. The preparation method comprises the following steps: carrying out primary grinding on quartz particles to obtain silica micropowder coarse powder; mixing the coarse silica powder, the grinding aid solution and the modifier solution, and performing ball milling to obtain a superfine material; and the superfine materials are pumped out through an induced draft system and then enter a grading system, and superfine silica powder is obtained. The D50 of the prepared superfine silica powder is 1.5-1.6 microns, the D97 of the superfine silica powder is 4.0-4.2 microns, the materials are fully premixed by a grinding aid and a modifier under the shearing action of a spiral reamer, the modification efficiency of ball-milling grinding is favorably improved, meanwhile, the materials in a ball mill are more efficiently ground in a limited space by utilizing a fine sub-bin of the ball mill, and the grinding efficiency of the ball mill is improved. The interface friction between the materials is increased, and the infiltration and coating of the grinding aid and the modifier on the materials are facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of silica powder preparation, and particularly relates to an ultrafine silica powder with integrated grinding and modification and a preparation method thereof. Background Art

[0002] Silica powder is a non-toxic, odorless, and pollution-free inorganic non-metallic material. Due to its excellent properties such as good heat resistance, acid and alkali corrosion resistance, high thermal conductivity, high insulation, low expansion, stable chemical properties, and high hardness, it is widely used in the fields of electronics, integrated circuits (ICs), electrical appliances, plastics, coatings, high-grade paints, rubber, etc.

[0003] Currently, the production processes of silica powder mainly include dry grinding and wet grinding. Among them, wet grinding mainly uses three grinding devices, namely sand mills, stirred mills, or horizontal wet ball mills, to produce products with fine particle sizes, and surface modification can be carried out during the wet grinding process. Since the materials are well dispersed in the liquid phase and have good interfacial wetting properties, the surface modification effect is better. However, the demand for modifiers is much larger than that of dry modification. At the same time, since additional material drying is required after wet grinding, the energy consumption is also relatively large. The dry grinding process mainly uses grinding devices such as ball mills, vibratory mills, or jet mills for grinding, and ultrafine silica powder is obtained by continuous mechanical rolling, impact grinding, and controlling the particle size with a classifier. The dry grinding process has a short process flow, does not require additional drying treatment later, and does not have wastewater treatment, which is a low-energy-consuming grinding process. However, since the subsequent classification system of the dry process uses centrifugal force for fineness screening, if surface modification is carried out during the grinding process, the specific gravity of the material will become smaller due to the coating of organic matter on the surface (especially for ultrafine silica powder products with a mesh size of more than 3000). It is more likely to be drawn away by the induced draft fan in the classification system and directly complete the classification. However, at this time, the fineness of the powder often does not reach the fineness required by actual production, so the final fineness of the finished product is likely to be too coarse. Therefore, in the dry production process, surface modification generally cannot be carried out during the grinding stage, and additional secondary surface modification is required, which is not conducive to the continuous production of products.

[0004] Therefore, it is of great significance to provide a preparation method for ultrafine silica powder with integrated grinding and modification. Summary of the Invention

[0005] The purpose of the present invention is to provide an ultrafine silica powder with integrated grinding and modification and a preparation method thereof in order to overcome the deficiencies of the prior art.

[0006] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a preparation method for ultrafine silica powder with integrated grinding and modification, comprising the following steps:

[0008] 1) Grind the quartz particles once to obtain coarse silica powder;

[0009] 2) Mix the coarse silica powder, grinding aid solution and modifier solution, and then carry out ball milling to obtain ultrafine materials;

[0010] 3) Extract the ultrafine materials through an air extraction system and then enter a classification system to obtain ultrafine silica powder.

[0011] Preferably, the particle size of the quartz particles in step 1) is 10 - 50 mm; the quartz particles are obtained by sequentially cleaning, drying, and subjecting natural quartz ore to two-stage crushing; the D50 of the coarse silica powder is 15.8 - 16.7 μm, and the D97 is 78 - 82 μm.

[0012] Preferably, in the modifier solution of step 2), the mass ratio of the modifier to water is 1:4 - 6; the mass of the modifier is 6 - 8‰ of the mass of the coarse silica powder; the modifier is two or three of N-(6-aminohexyl)aminomethyltriethoxysilane, polyethylene glycol trimethoxysilylpropyl ether, and neoalkoxy tris(ethylenediamino N-ethoxy)titanate.

[0013] Preferably, in the grinding aid solution of step 2), the mass ratio of the grinding aid to water is 1:3 - 5; the mass of the grinding aid is 4 - 8‰ of the mass of the coarse silica powder; the grinding aid is a low molecular weight fatty acid-modified emulsifier and polyethylene glycol, and the mass ratio of the low molecular weight fatty acid-modified emulsifier to polyethylene glycol is 1:2 - 3.

[0014] Preferably, the grinding aid solution and the modifier solution are independently added in the form of spray. The grinding aid solution is added at the front section of the conveying system, and the modifier solution is added at the middle section of the conveying system.

[0015] Preferably, the ball mill used in step 2) is a four-compartment ball mill, and the volume ratio of the first compartment, the second compartment, the third compartment, and the fourth compartment is 2.5 - 3.5:2.5 - 3.5:2.5 - 3.5:3.5 - 4.5; the medium for the ball milling is ceramic balls, and the filling rate of the medium is 50 - 60%.

[0016] Preferably, in the first compartment, the mass ratio of the medium with a particle size of 60 mm, the medium with a particle size of 50 mm, and the medium with a particle size of 40 mm is 2 - 3:1 - 2:1; in the second compartment, the mass ratio of the medium with a particle size of 50 mm, the medium with a particle size of 40 mm, and the medium with a particle size of 30 mm is 3:1 - 2:1; in the third compartment, the mass ratio of the medium with a particle size of 30 mm and the medium with a particle size of 20 mm is 1:2 - 3; in the fourth compartment, the mass ratio of the medium with a particle size of 20 mm and the medium with a particle size of 10 mm is 1:2 - 4.

[0017] Preferably, the frequency of the classification system in step 3) is 65 - 66 Hz, and the frequency of the air extraction system is 47.3 - 47.4 Hz.

[0018] The present invention also provides an ultrafine silica powder with integrated grinding and modification prepared by the described preparation method.

[0019] The beneficial effects of the present invention include the following points:

[0020] 1) Aiming at the defect that in the prior art, dry production of silica powder cannot directly perform surface modification during the grinding process and requires additional secondary modification, the present invention proposes a preparation method for dry grinding production of ultrafine silica powder with integrated grinding and modification, which has a simple process and a short production process.

[0021] 2) The D50 of the ultrafine silica powder prepared by the present invention is 1.5 - 1.6 μm, and the D97 is 4.0 - 4.2 μm. Before grinding, the shearing action of the spiral auger is used to fully premix the grinding aid and the modifier with the material, which is beneficial to improving the modification efficiency of ball mill grinding. At the same time, the refined bin of the ball mill enables the materials in the mill to be ground more efficiently in a limited space, increasing the interfacial friction between the materials, which is beneficial to the infiltration and coating of the grinding aid and the modifier on the materials, and improving the effect of ball mill modification.

[0022] 3) The classification system of the present invention is a horizontal 6-rotor air classification system. Compared with the vertical air classification system, the classification efficiency is higher. At the same time, the classification wheel is a straight-edge alumina ceramic classification wheel, and the classification efficiency is further improved compared with the conventional bevel-edge classification wheel. By adjusting the frequency of the induced draft fan to control the material concentration in the classification wheel, it is avoided that the material concentration is too high or too low, thus affecting the classification accuracy and efficiency of the classification system. Description of the Drawings

[0023] Figure 1 It is a process flow chart of the preparation of the ultrafine silica powder with integrated grinding and modification of the present invention. Detailed Embodiments

[0024] The present invention provides a preparation method for ultrafine silica powder with integrated grinding and modification, comprising the following steps:

[0025] 1) Grind the quartz particles once to obtain coarse silica powder;

[0026] 2) Mix the coarse silica powder, the grinding aid solution and the modifier solution, and then perform ball milling to obtain ultrafine materials;

[0027] 3) Extract the ultrafine materials through the air extraction system and then enter the classification system to obtain ultrafine silica powder.

[0028] In the present invention, the particle size of the quartz particles in step 1) is preferably 10-50 mm, more preferably 20-40 mm, and still more preferably 30 mm; the quartz particles are preferably obtained by successively cleaning, drying, and subjecting natural quartz ore to two-stage crushing; the coarse silicon micropowder preferably has a D50 of 15.8-16.7 μm and a D97 of 78-82 μm, more preferably a D50 of 16-16.5 μm and a D97 of 79-81 μm, and still more preferably a D50 of 16.21-16.33 μm and a D97 of 80.04-80.56 μm.

[0029] In the present invention, the quartz particles are transported by a spiral auger into a vertical pendulum mill for primary grinding, and the model of the vertical pendulum mill is HC-1700.

[0030] In the present invention, in the natural quartz ore, the mass content of silicon dioxide is preferably ≥99%, more preferably ≥99.2%; the two-stage crushing is successively jaw crushing and hammer crushing.

[0031] In the present invention, in the modifier solution in step 2), the mass ratio of the modifier to water is preferably 1:4-6, more preferably 1:4.5-5.5, and still more preferably 1:5; the mass of the modifier is preferably 6-8‰ of the mass of the coarse silicon micropowder, more preferably 6.5-7.5‰, and still more preferably 7‰; the modifier is preferably two or three of N-(6-aminohexyl)aminomethyltriethoxysilane, polyethylene glycol trimethoxysilylpropyl ether, and neopentoxy tri(ethylenediamine N-ethoxy) titanate.

[0032] In the present invention, in the grinding aid solution in step 2), the mass ratio of the grinding aid to water is preferably 1:3-5, more preferably 1:3.5-4.5, and still more preferably 1:4; the mass of the grinding aid is preferably 4-8‰ of the mass of the coarse silicon micropowder, more preferably 5-7‰, and still more preferably 6‰; the grinding aid is preferably a low molecular weight fatty acid modified emulsifier and polyethylene glycol, and the mass ratio of the low molecular weight fatty acid modified emulsifier to polyethylene glycol is preferably 1:2-3, more preferably 1:2.2-2.8, and still more preferably 1:2.5-2.6.

[0033] In the present invention, the grinding aid solution and the modifier solution are independently added in the form of a spray. The grinding aid solution is preferably added at the front stage of the conveying system, and the modifier solution is preferably added at the middle stage of the conveying system.

[0034] In the present invention, the coarse silicon micropowder is transported into a ball mill by a two-stage spiral auger conveying system.

[0035] In the present invention, the ball mill used in step 2) is preferably a four-compartment ball mill, and the volume ratio of the first compartment, the second compartment, the third compartment, and the fourth compartment is preferably 2.5-3.5:2.5-3.5:2.5-3.5:3.5-4.5, more preferably 3:3:3:4; the medium for ball milling is preferably ceramic balls, and the filling rate of the medium is preferably 50-60%, more preferably 52-58%, and even more preferably 55-56%.

[0036] In the present invention, the four-compartment ball mill is a four-compartment ball mill with a full ceramic lining, and the specification of the ball mill is 3.5m×13m; through refined compartmentalization, the materials in the mill can be ground more efficiently in a limited space, while increasing the interfacial friction between the materials, which is beneficial to the infiltration and coating of the grinding aid and the modifier on the materials, and improving the effect of ball milling modification.

[0037] In the present invention, in the first compartment, the mass ratio of the medium with a particle size of 60mm, the medium with a particle size of 50mm, and the medium with a particle size of 40mm is preferably 2-3:1-2:1, more preferably 2.5:1.5:1; in the second compartment, the mass ratio of the medium with a particle size of 50mm, the medium with a particle size of 40mm, and the medium with a particle size of 30mm is preferably 3:1-2:1, more preferably 3:1.5:1; in the third compartment, the mass ratio of the medium with a particle size of 30mm and the medium with a particle size of 20mm is preferably 1:2-3, more preferably 1:2.5; in the fourth compartment, the mass ratio of the medium with a particle size of 20mm and the medium with a particle size of 10mm is preferably 1:2-4, more preferably 1:2.5-3.5, and even more preferably 1:3.

[0038] In the present invention, the frequency of the classification system in step 3) is preferably 65-66Hz, and the frequency of the air induction system is preferably 47.3-47.4Hz.

[0039] In the present invention, the classification system is a horizontal 6-rotor air current classification system, which consists of 6 straight-edge alumina ceramic classification wheels, and the classification efficiency and accuracy of the straight-edge classification wheels are higher; the spiral auger conveying system is a reciprocating three-section evenly distributed system with a total length of 24m. Through the reciprocating three-section distribution, the grinding aids and modifiers are preliminarily premixed with the materials during the conveying process, which is more beneficial to the effect of ball milling and modification.

[0040] The present invention also provides a superfine silica powder with integrated grinding and modification prepared by the preparation method described above.

[0041] The technical solutions provided by the present invention will be described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0042] In the embodiment, the four-compartment ball mill is a four-compartment ball mill with a full ceramic lining, and the specification of the four-compartment ball mill is 3.5m×13m; the classification system is a horizontal 6-rotor air classification system, which consists of 6 straight-edge alumina ceramic classification wheels;

[0043] The spiral auger conveying system is reciprocating and evenly distributed in three sections, with a total length of 24m; the spiral auger conveying systems for conveying coarse silicon micropowder and quartz particles are two identical systems; the model of the vertical pendulum mill is HC-1700;

[0044] The grade of the low molecular weight fatty acid modified emulsifier is: Efka 6220, and the manufacturer is BASF SE.

[0045] Example 1

[0046] The natural quartz ore with a silicon dioxide content of 99% is cleaned with deionized water, dried, jaw-crushed, and hammer-crushed to obtain quartz particles with a diameter of 10-50mm, which are conveyed into the vertical pendulum mill by a spiral auger for primary grinding to obtain coarse silicon micropowder with D50 of 16.33μm and D97 of 80.56μm.

[0047] The coarse silicon micropowder is conveyed into the four-compartment ball mill by a spiral auger. The filling rate of the grinding medium is 50%, and the grinding medium is zirconia ceramic balls. The volume ratio of the first compartment, the second compartment, the third compartment, and the fourth compartment is 3:3:3:4. In the first compartment, the mass ratio of the medium with a particle size of 60mm, the medium with a particle size of 50mm, and the medium with a particle size of 40mm is 2:1:1. In the second compartment, the mass ratio of the medium with a particle size of 50mm, the medium with a particle size of 40mm, and the medium with a particle size of 30mm is 3:1:1. In the third compartment, the mass ratio of the medium with a particle size of 30mm and the medium with a particle size of 20mm is 1:2. In the fourth compartment, the mass ratio of the medium with a particle size of 20mm and the medium with a particle size of 10mm is 1:2.

[0048] The grinding aid and deionized water are mixed at a mass ratio of 1:3 to obtain a grinding aid solution; the modifier and deionized water are mixed at a mass ratio of 1:4 to obtain a modifier solution; the grinding aid solution is added by spraying in the front section of the spiral auger conveying system (the grinding aid is a low molecular weight fatty acid modified emulsifier and polyethylene glycol with a mass ratio of 1:2, and the mass of the grinding aid is 4‰ of the mass of the coarse silicon micropowder), and the modifier solution is added by spraying in the middle section (the modifier is N-(6-aminohexyl)aminomethyltriethoxysilane and polyethylene glycol trimethoxysilylpropyl ether with a mass ratio of 1:1, and the mass of the modifier is 6‰ of the mass of the coarse silicon micropowder).

[0049] The material after ultrafine grinding is extracted by the induced air system (the frequency of the induced draft fan is 47.3 Hz) and then enters the horizontal 6-rotor air classification system (the frequency of the classifier is 65 Hz). The product with the required fineness is collected by a cyclone and enters the finished product bin. After being detected by the BT-9300ST laser particle size analyzer, the D50 of the product is 1.58 μm, the D97 is 4.17 μm, and then it is sieved, detected, and packaged.

[0050] Example 2

[0051] The natural quartz ore with a silica content of 99.2% is washed with deionized water, dried, jaw-crushed, and hammer-crushed to obtain quartz particles with a diameter of 20 - 40 mm. They are transported by a spiral auger into a vertical pendulum mill for primary grinding to obtain a coarse silicon micropowder with D50 of 16.21 μm and D97 of 80.04 μm.

[0052] The coarse silicon micropowder is transported by a spiral auger into a four-compartment ball mill. The filling rate of the grinding medium is 55%, and the grinding medium is zirconia ceramic balls. The volume ratio of the first compartment, the second compartment, the third compartment, and the fourth compartment is 3:3:3:4. In the first compartment, the mass ratio of the medium with a particle size of 60 mm, the medium with a particle size of 50 mm, and the medium with a particle size of 40 mm is 3:2:1. In the second compartment, the mass ratio of the medium with a particle size of 50 mm, the medium with a particle size of 40 mm, and the medium with a particle size of 30 mm is 3:2:1. In the third compartment, the mass ratio of the medium with a particle size of 30 mm and the medium with a particle size of 20 mm is 1:3. In the fourth compartment, the mass ratio of the medium with a particle size of 20 mm and the medium with a particle size of 10 mm is 1:3.

[0053] The grinding aid and deionized water are mixed at a mass ratio of 1:4 to obtain a grinding aid solution; the modifier and deionized water are mixed at a mass ratio of 1:5 to obtain a modifier solution; the grinding aid solution is added by spraying in the front section of the spiral auger conveying system (the grinding aid is a low molecular weight fatty acid modified emulsifier and polyethylene glycol with a mass ratio of 1:3, and the mass of the grinding aid is 6‰ of the mass of the coarse silicon micropowder), and the modifier solution is added by spraying in the middle section (the modifier is N-(6-aminohexyl)aminomethyltriethoxysilane and neoalkoxy tris(ethylenediamino N-ethoxy) titanate with a mass ratio of 3:4, and the mass of the modifier is 7‰ of the mass of the coarse silicon micropowder).

[0054] The material after ultrafine grinding is extracted by the induced air system (the frequency of the induced draft fan is 47.3 Hz) and then enters the horizontal 6-rotor air classification system (the frequency of the classifier is 65 Hz). The product with the required fineness is collected by a cyclone and enters the finished product bin. After being detected by the BT-9300ST laser particle size analyzer, the D50 of the product is 1.56 μm, the D97 is 4.15 μm, and then it is sieved, detected, and packaged.

[0055] Example 3

[0056] The natural quartz ore with a silicon dioxide content of 99.2% is washed with deionized water, dried, crushed by jaws and hammered to obtain quartz particles with a diameter of 10 to 50 mm, which are transported into a vertical pendulum mill through a spiral auger for a single grinding to obtain coarse silicon micropowder with a D50 of 16.31 μm and a D97 of 80.12 μm.

[0057] The coarse silicon micropowder is transported into the four-bin ball mill through a spiral auger. The grinding medium filling rate is 60%, and the grinding medium is zirconia ceramic balls. The volume ratio of the first bin, the second bin, the third bin and the fourth bin is 3:3:3:4. In the first bin, the mass ratio of the medium with a particle size of 60 mm, the medium with a particle size of 50 mm and the medium with a particle size of 40 mm is 3:2:1. In the second bin, the mass ratio of the medium with a particle size of 50 mm, the medium with a particle size of 40 mm and the medium with a particle size of 30 mm is 3:2:1. In the third bin, the mass ratio of the medium with a particle size of 30 mm and the medium with a particle size of 20 mm is 1:3. In the fourth bin, the mass ratio of the medium with a particle size of 20 mm and the medium with a particle size of 10 mm is 1:4.

[0058] A grinding aid and deionized water are mixed in a mass ratio of 1:5 to obtain a grinding aid solution; a modifier and deionized water are mixed in a mass ratio of 1:6 to obtain a modifier solution; the grinding aid solution is added by spraying in the front section of the spiral cutter conveying system (the grinding aid is a low molecular weight fatty acid modified emulsifier and polyethylene glycol in a mass ratio of 1:3, and the mass of the grinding aid is 8‰ of the mass of the coarse silicon micropowder), and a modifier solution is added by spraying in the middle section (the modifier is N-(6-aminohexyl)aminomethyltriethoxysilane, polyethylene glycol trimethoxysilyl propyl ether and neoalkoxy tris(ethylenediamino N-ethoxy) titanate in a mass ratio of 3:3:2, and the mass of the modifier is 8‰ of the mass of the coarse silicon micropowder).

[0059] The ultra-finely ground materials are extracted through the induced draft system (the frequency of the induced draft fan is 47.3Hz) and then enter the horizontal 6-rotor airflow classification system (the frequency of the classifier is 66Hz). The products that meet the fineness requirements are collected by the cyclone and enter the finished product silo. After the product is tested by the BT-9300ST laser particle size analyzer, the D50 is 1.52μm and the D97 is 4.11μm. They are then sieved, tested and packaged.

[0060] The ultrafine silicon micropowder prepared by ball milling modification in Examples 1 to 3 and the conventional intermittent modified silicon micropowder (first grinding to obtain silicon micropowder raw powder, and then surface modification, grinding and modification are separate) were tested for relevant indicators according to SJ / T10675-2002, and the test results are shown in Table 1.

[0061] Table 1 Performance test results of ultrafine silicon powder and conventional intermittent modified silicon powder of Examples 1 to 3

[0062]

[0063] As can be seen from Table 1, compared with the conventional batch-modified silica powder, under the condition of the same fineness, the whiteness, oil absorption, contact angle and other indexes of the ultrafine silica powder prepared by the present invention are significantly better than those of the conventional batch-modified silica powder. At the same time, due to the adoption of the all-ceramic grinding and classification process, the content of magnetic substances in the ultrafine silica powder of the present invention is significantly better than that of the conventional batch-modified silica powder. Judging from Table 1 comprehensively, the ultrafine silica powder prepared by the method of the present invention realizes the integration of grinding and modification of dry-process silica powder, and the modification effect is better than that of the conventional batch-modified process.

[0064] The above is only the preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of ultrafine silica powder with integrated grinding and modification, characterized in that, It includes the following steps: 1) Grind the quartz particles once to obtain coarse silicon micropowder; 2) Mix the coarse silicon micropowder, grinding aid solution and modifier solution and then carry out ball milling to obtain ultrafine materials; 3) After the ultrafine materials are extracted by an air induction system, they enter a classification system to obtain ultrafine silicon micropowder.

2. The preparation method according to claim 1, characterized in that, In step 1), the particle size of the quartz particles is 10 - 50 mm; the quartz particles are obtained by successively cleaning, air-drying and two-stage crushing of natural quartz ore; the D50 of the coarse silicon micropowder is 15.8 - 16.7 μm, and the D97 is 78 - 82 μm.

3. The preparation method according to claim 1 or 2, characterized in that, In step 2), the mass ratio of the modifier to water in the modifier solution is 1:4 - 6; the mass of the modifier is 6 - 8‰ of the mass of the coarse silicon micropowder; the modifier is two or three of N-(6-aminohexyl)aminomethyltriethoxysilane, polyethylene glycol trimethoxysilylpropyl ether and neopentoxy tris(ethylenediamino N-ethoxy) titanate.

4. The preparation method according to claim 3, wherein In step 2), the mass ratio of the grinding aid to water in the grinding aid solution is 1:3 - 5; the mass of the grinding aid is 4 - 8‰ of the mass of the coarse silicon micropowder; the grinding aid is a low molecular weight fatty acid modified emulsifier and polyethylene glycol, and the mass ratio of the low molecular weight fatty acid modified emulsifier to polyethylene glycol is 1:2 - 3.

5. The preparation method according to claim 4, characterized in that, The grinding aid solution and the modifier solution are independently added in the form of spray. The grinding aid solution is added in the front section of the conveying system, and the modifier solution is added in the middle section of the conveying system.

6. The preparation method according to claim 4, characterized in that, In step 2), the ball mill used for ball milling is a four-compartment ball mill, and the volume ratio of the first compartment, the second compartment, the third compartment and the fourth compartment is 2.5 - 3.5:2.5 - 3.5:2.5 - 3.5:3.5 - 4.5; the medium for ball milling is ceramic balls, and the filling rate of the medium is 50 - 60%.

7. The preparation method according to claim 6, wherein In the first compartment, the mass ratio of the medium with a particle size of 60 mm, the medium with a particle size of 50 mm and the medium with a particle size of 40 mm is 2 - 3:1 - 2:1; in the second compartment, the mass ratio of the medium with a particle size of 50 mm, the medium with a particle size of 40 mm and the medium with a particle size of 30 mm is 3:1 - 2:1; in the third compartment, the mass ratio of the medium with a particle size of 30 mm and the medium with a particle size of 20 mm is 1:2 - 3; in the fourth compartment, the mass ratio of the medium with a particle size of 20 mm and the medium with a particle size of 10 mm is 1:2 - 4.

8. The preparation method according to any one of claims 5 to 7, characterized in that, In step 3), the frequency of the classification system is 65 - 66 Hz, and the frequency of the air induction system is 47.3 - 47.4 Hz.

9. Ultrafine silicon micropowder with integrated grinding and modification prepared by the preparation method according to any one of claims 1 - 8.

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