High-purity silica powder and preparation method thereof

Abstract

The invention belongs to the technical field of silica powder preparation, and discloses high-purity silica powder and a preparation method thereof. The preparation method of the high-purity silica powder comprises the following steps: mixing silicon powder and a grinding aid, and grinding to obtain the silica powder, reacting the silica powder with the purification solution, and then adding a modifier for modification to obtain high-purity silica powder; the purification solution is obtained by mixing hydrochloric acid, hydrofluoric acid and water. In the preparation method of the high-purity silica powder, waste materials and waste gas generated in each link are reasonably treated and recycled, so that environmental pollution is reduced, and green and environment-friendly production is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon micropowder preparation, and in particular to high-purity silicon micropowder and a preparation method thereof. Background Art

[0002] Silica powder is a non-toxic, odorless, and pollution-free inorganic non-metallic material with excellent properties such as high insulation, low thermal expansion coefficient, and chemical stability. It is widely used in electronics, chemicals, building materials and other fields.

[0003] At present, there are many methods for preparing silicon micropowder. With the updating and iterative development of products, the performance requirements for silicon micropowder are getting higher and higher. Silicon micropowder prepared by traditional methods often has problems such as low purity, high energy consumption, and environmental pollution, which limits the quality improvement and wider application of silicon micropowder. Based on this, the method of using quartz minerals to prepare high-purity silicon micropowder in a process that achieves high efficiency, low consumption, and environmental protection still needs further exploration and improvement.

[0004] Therefore, it is of great significance to study and obtain a high-purity silicon micropowder and a low-consumption and environmentally friendly preparation method. Summary of the Invention

[0005] In view of this, the present invention provides a high-purity silicon micropowder and a preparation method thereof, the purpose of which is to solve the problems of low preparation efficiency, high energy consumption and certain impact on the environment in the prior art of preparing silicon micropowder using quartz minerals.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for preparing high-purity silicon micropowder, comprising the following preparation steps: 1) Mixing silicon powder with a grinding aid and grinding to obtain silicon micropowder; 2) reacting the silicon micropowder with the purified solution, and then adding a modifier to modify it to obtain high-purity silicon micropowder; The purification solution in step 2) is obtained by mixing hydrochloric acid, hydrofluoric acid and water.

[0007] Preferably, in step 1), the particle size of the silicon powder is 300-350 mesh; The silicon powder is obtained by crushing quartz ore, and the silicon content of the quartz ore is ≥99.2%.

[0008] Preferably, in step 1), the grinding aid is one or more of sodium hexametaphosphate, polyethylene glycol and ammonium lignin sulfonate; The mass ratio of silicon powder to grinding aid is 1000:6~8.

[0009] Preferably, in step 1), the grinding speed is 25-30 rpm, the grinding time is 2-4 h, the grinding ball-to-material ratio is 45-55:45-55, the grinding medium is ceramic balls, and the diameter of the ceramic balls is 20-40 mm.

[0010] Preferably, in step 1), the particle size of the silicon micropowder is 2800-3200 mesh.

[0011] Preferably, in step 2), the volume ratio of hydrochloric acid, hydrofluoric acid and water in the purification solution is 1:1:4-7; The dosage ratio of silicon micropowder to purification solution is 1g:3~4mL.

[0012] Preferably, in step 2), the reaction time is 2-3 hours and the reaction temperature is 50-70°C.

[0013] Preferably, in step 2), the modifier is one or more of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-diethylenetriaminopropyltrimethoxysilane and γ-aminopropylmethyldiethoxysilane; The mass ratio of silicon micropowder to modifier is 100:1~4.

[0014] Preferably, in step 2), the modification time is 30-40 minutes, and the modification temperature is 90-120°C; The modification is carried out under stirring at a stirring speed of 1200-1600 rpm.

[0015] The present invention also provides high-purity silicon micropowder prepared by the method for preparing high-purity silicon micropowder.

[0016] It can be seen from the above technical solutions that compared with the prior art, the present invention has the following beneficial effects: In the preparation method of the present invention, waste materials and waste gas generated in each link are reasonably treated and recycled, thereby reducing environmental pollution and achieving green and environmentally friendly production.

[0017] The high-purity silicon micropowder obtained by the present invention has a particle size of D50≤4.5μm, D70≤12.8μm, an oil absorption value of 23~24mL / 100g, an activation degree ≥97.5%, and a silicon content ≥99.7%. The high-purity silicon micropowder obtained by the present invention has excellent particle size, activation degree and silicon content. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0019] Figure 1 This is an electron microscope photograph of the silicon powder obtained in Example 1; Figure 2 Schematic diagram of the process flow of the present invention. DETAILED DESCRIPTION

[0020] The present invention provides a method for preparing high-purity silicon micropowder, comprising the following preparation steps: 1) Mixing silicon powder with a grinding aid and grinding to obtain silicon micropowder; 2) reacting the silicon micropowder with the purified solution, and then adding a modifier to modify it to obtain high-purity silicon micropowder; The purification solution in step 2) is obtained by mixing hydrochloric acid, hydrofluoric acid and water.

[0021] In the present invention, in step 1), the particle size of the silicon powder is preferably 300-350 mesh, more preferably 310-340 mesh, and even more preferably 320-330 mesh; The silicon powder is obtained by crushing quartz ore, and the silicon content of the quartz ore is preferably ≥99.2%, more preferably ≥99.4%, and even more preferably ≥99.6%.

[0022] In the present invention, after the quartz ore is crushed, it is preferably washed, dried and roller milled in sequence to obtain silicon powder; the pretreatment steps effectively reduce the impurity content in the raw material, laying the foundation for the subsequent preparation of high-purity silicon powder.

[0023] In the present invention, in step 1), the grinding aid is preferably one or more of sodium hexametaphosphate, polyethylene glycol and ammonium lignin sulfonate; The mass ratio of silicon powder to grinding aid is preferably 1000:6-8, more preferably 1000:6.5-7.5, and even more preferably 1000:7.

[0024] In the present invention, in the step 1), the grinding speed is preferably 25-30 rpm, more preferably 26-29 rpm, more preferably 27-28 rpm, the grinding time is preferably 2-4 h, more preferably 2.5-3.5 h, more preferably 3 h, the grinding ball-to-material ratio is preferably 45-55:45-55, more preferably 47-52:48-53, more preferably 48-50:50-52, the grinding medium is preferably ceramic balls, and the diameter of the ceramic balls is preferably 20-40 mm, more preferably 25-35 mm, more preferably 30-32 mm.

[0025] In the present invention, in step 1), the grinding is preferably performed by all-ceramic ball milling; the coordinated control of the grinding equipment and process parameters ensures the particle size uniformity and fine powder rate of the silicon micropowder, thereby improving production efficiency and product quality.

[0026] In the present invention, in step 1), the particle size of the silicon powder is preferably 2800-3200 mesh, more preferably 2850-3100 mesh, and even more preferably 2900-3000 mesh.

[0027] In the present invention, in step 2), the volume ratio of hydrochloric acid, hydrofluoric acid and water in the purification solution is preferably 1:1:4-7, more preferably 1:1:4.5-6, and more preferably 1:1:5-5.5; The concentration of the hydrochloric acid is preferably 40-55%, more preferably 43-52%, and even more preferably 45-50%.

[0028] The ratio of silicon micropowder to purification solution is preferably 1 g: 3-4 mL, more preferably 1 g: 3.2-3.8 mL, and even more preferably 1 g: 3.5-3.6 mL.

[0029] In the present invention, in the step 2), the reaction time is preferably 2-3 h, more preferably 2.5 h, the reaction temperature is preferably 50-70 ° C, more preferably 55-65 ° C, more preferably 60-62 ° C, and the reaction is preferably carried out under stirring. The stirring rate is preferably 25-30 rpm, more preferably 26-29 rpm, and more preferably 27-28 rpm.

[0030] In the present invention, in step 2), the modifier is preferably one or more of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-diethylenetriaminopropyltrimethoxysilane and γ-aminopropylmethyldiethoxysilane; The mass ratio of silicon powder to modifier is preferably 100:1-4, more preferably 100:1.5-3.5, and even more preferably 100:2-3.

[0031] In the present application, the modifier is uniformly coated on the surface of the silicon powder, enhancing the compatibility and dispersibility of the silicon powder in the subsequent application system.

[0032] In the step 2), the modification time is preferably 30-40 min, further preferably 32-38 min, and more preferably 35-36 min, and the modification temperature is preferably 90-120℃, further preferably 95-115℃, and more preferably 100-110℃. The modification is preferably carried out under stirring, and the stirring speed is preferably 1200-1600 rpm, further preferably 1300-1550 rpm, and more preferably 1400-1500 rpm.

[0033] In the present application, the combination of chemical purification and surface modification treatment not only significantly improves the purity of the silicon powder, but also improves the surface properties of the silicon powder, so that the silicon powder has better performance in application, such as increasing the filling rate and material performance stability in electronic packaging materials.

[0034] In the preparation method, bag-type dust collector, wet dust collector, cyclone dust collector and activated carbon adsorption device are used in the steps of raw material grinding, screening and packaging, etc. The dust removal efficiency of the bag-type dust collector is as high as 99% or more, which can effectively remove a large amount of fine dust. The wet dust collector can combine more than 95% of the dust in the waste gas with water droplets to be removed, and the treatment effect is remarkable for waste gas containing more moisture. When treating large flow waste gas, the cyclone dust collector can separate 80-90% of the dust particles by centrifugal force. The activated carbon adsorption device has an adsorption efficiency of about 90% for waste gas containing organic gas, which greatly reduces the emission of harmful gas. Through the synergistic operation of these devices, the removal rate of harmful substances such as dust and silicon dioxide in waste gas can reach more than 95%, ensuring that the discharged waste gas meets the relevant national environmental protection standards.

[0035] The present application uses innovative technology to achieve a utilization rate of 90% for silicon slag and other waste materials. After treatment, these waste materials are re-injected into the production process, reducing the demand for new raw materials and production costs, and reducing the environmental impact of waste storage. At the same time, other solid waste generated during the production process is also classified and recycled, and the comprehensive utilization rate is more than 85%, effectively reducing the emission of solid waste.

[0036] The present application also provides a high-purity silicon powder prepared by the preparation method of the high-purity silicon powder.

[0037] The technical solutions provided by the present application will be described in detail below in conjunction with the embodiments, but they should not be understood as limiting the scope of protection of the present application.

[0038] In the embodiment of the present invention, the grinding equipment for quartz stone ore is a 198-type ring grinding roller purchased from Longyan Yifeng Machinery Technology Co., Ltd.

[0039] Example 1

[0040] Quartz ore with a silicon content of 99.2% was crushed, washed with water, dried and ground to obtain silicon powder with a particle size of 325 mesh; A grinding aid (prepared by mixing sodium hexametaphosphate, polyethylene glycol, and ammonium lignin sulfonate in a mass ratio of 2:1:1) was added to the silicon powder at a mass ratio of 1000:6, and then ground and classified by an all-ceramic ball mill to obtain silicon micropowder with a particle size of 3000 mesh. The parameters of the all-ceramic ball mill were set as follows: speed of 25 rpm, grinding time of 2 h, grinding medium of 30 mm diameter ceramic balls, and ball-to-material ratio of 45:55. The obtained silicon micropowder was placed in a purification solution (the volume ratio of hydrochloric acid, hydrofluoric acid and water was 1:1:4, and the concentration of hydrochloric acid was 45%), the amount ratio of silicon micropowder to purification solution was 1g:3mL, and the reaction was stirred at 50°C at a stirring rate of 28rpm for 2h. Then, a modifier (obtained by mixing γ-aminopropyltriethoxysilane and γ-aminopropylmethyldiethoxysilane in a mass ratio of 1:1) was added to the modified silicon micropowder according to the mass ratio of silicon micropowder to modifier being 100:1, and the modification was carried out at 100°C at a rotation speed of 1200rpm for 30min to obtain high-purity silicon micropowder.

[0041] Example 2

[0042] Quartz ore with a silicon content of 99.2% was crushed, washed with water, dried and ground to obtain silicon powder with a particle size of 325 mesh; A grinding aid (prepared by mixing sodium hexametaphosphate, polyethylene glycol, and ammonium lignin sulfonate in a mass ratio of 2:1:1) was added to the silicon powder at a mass ratio of 1000:7, and then ground and classified by an all-ceramic ball mill to obtain silicon micropowder with a particle size of 3000 mesh. The parameters of the all-ceramic ball mill were set as follows: speed of 27 rpm, grinding time of 3 hours, grinding medium of 30 mm diameter ceramic balls, and ball-to-material ratio of 50:50. The obtained silicon micropowder was placed in a purification solution (the volume ratio of hydrochloric acid, hydrofluoric acid and water was 1:1:5, and the concentration of hydrochloric acid was 45%), the amount ratio of silicon micropowder to purification solution was 1g:3mL, and the reaction was stirred at 60°C at a stirring rate of 28rpm for 2h. Then, a modifier (obtained by mixing γ-aminopropyltriethoxysilane and γ-aminopropylmethyldiethoxysilane in a mass ratio of 1:1) was added to the modified silicon micropowder according to the mass ratio of silicon micropowder to modifier of 100:1.5, and the modification was carried out at 110°C at a rotation speed of 1400rpm for 35min to obtain high-purity silicon micropowder.

[0043] Example 3

[0044] Quartz ore with a silicon content of 99.2% was crushed, washed with water, dried and ground to obtain silicon powder with a particle size of 325 mesh; A grinding aid (prepared by mixing sodium hexametaphosphate, polyethylene glycol, and ammonium lignin sulfonate in a mass ratio of 2:1:1) was added to the silicon powder at a mass ratio of 1000:8, and then ground and classified by an all-ceramic ball mill to obtain silicon micropowder with a particle size of 3000 mesh. The parameters of the all-ceramic ball mill were set as follows: speed of 29 rpm, grinding time of 4 h, grinding medium of 30 mm diameter ceramic balls, and ball-to-material ratio of 55:45. The obtained silicon micropowder was placed in a purification solution (the volume ratio of hydrochloric acid, hydrofluoric acid and water was 1:1:6, and the concentration of hydrochloric acid was 48%), the amount ratio of silicon micropowder to purification solution was 1g:3mL, and the reaction was stirred at 70°C at a stirring rate of 28rpm for 3h. Then, a modifier (obtained by mixing γ-aminopropyltriethoxysilane and γ-aminopropylmethyldiethoxysilane in a mass ratio of 1:1) was added to the modified silicon micropowder according to the mass ratio of silicon micropowder to modifier of 100:2, and the modification was carried out at 120°C at a rotation speed of 1600rpm for 40min to obtain high-purity silicon micropowder.

[0045] Example 4

[0046] Quartz ore with a silicon content of 99.2% was crushed, washed with water, dried and ground to obtain silicon powder with a particle size of 325 mesh; A grinding aid (prepared by mixing sodium hexametaphosphate, polyethylene glycol, and ammonium lignin sulfonate in a mass ratio of 2:1:1) was added to the silicon powder at a mass ratio of 1000:7, and then ground and classified by an all-ceramic ball mill to obtain silicon micropowder with a particle size of 3000 mesh. The parameters of the all-ceramic ball mill were set as follows: rotation speed of 30 rpm, grinding time of 4 hours, grinding medium of 30 mm diameter ceramic balls, and ball-to-material ratio of 55:45. The obtained silicon micropowder was placed in a purification solution (the volume ratio of hydrochloric acid, hydrofluoric acid and water was 1:1:7, and the concentration of hydrochloric acid was 48%), the amount ratio of silicon micropowder to purification solution was 1g:4mL, and the reaction was stirred at 70°C at a stirring rate of 27rpm for 3h. Then, a modifier (obtained by mixing γ-aminopropyltriethoxysilane and γ-aminopropylmethyldiethoxysilane in a mass ratio of 1:1) was added to the modified silicon micropowder according to the mass ratio of silicon micropowder to modifier of 100:2, and the modified product was modified at 120°C at a speed of 1600rpm for 40min to obtain high-purity silicon micropowder.

[0047] Example 5

[0048] Quartz ore with a silicon content of 99.2% was crushed, washed with water, dried and ground to obtain silicon powder with a particle size of 325 mesh; A grinding aid (prepared by mixing sodium hexametaphosphate, polyethylene glycol, and ammonium lignin sulfonate in a mass ratio of 2:1:1) was added to the silicon powder at a mass ratio of 1000:7, and then ground and classified by an all-ceramic ball mill to obtain silicon micropowder with a particle size of 3000 mesh. The parameters of the all-ceramic ball mill were set as follows: speed of 28 rpm, grinding time of 3 hours, grinding medium of 30 mm diameter ceramic balls, and ball-to-material ratio of 50:50. The obtained silicon micropowder was placed in a purification solution (the volume ratio of hydrochloric acid, hydrofluoric acid and water was 1:1:5, and the concentration of hydrochloric acid was 50%), the amount ratio of silicon micropowder to purification solution was 1g:4mL, and the reaction was stirred at 60°C at a stirring rate of 27rpm for 2.5h. Then, a modifier (obtained by mixing γ-aminopropyltriethoxysilane and γ-aminopropylmethyldiethoxysilane in a mass ratio of 1:1) was added to the modified silicon micropowder according to the mass ratio of silicon micropowder to modifier of 100:2, and the modification was carried out at 110°C at a rotation speed of 1400rpm for 35min to obtain high-purity silicon micropowder.

[0049] Comparative Example 1

[0050] Quartz ore with a silicon content of 99.2% was crushed, washed with water, dried and ground to obtain silicon powder with a particle size of 325 mesh; A grinding aid (prepared by mixing sodium hexametaphosphate, polyethylene glycol, and ammonium lignin sulfonate in a mass ratio of 2:1:1) was added to the silicon powder at a mass ratio of 1000:7, and then ground and classified by a jet mill to obtain silicon micropowder with a particle size of 3000 mesh; A modifier (prepared by mixing γ-aminopropyltriethoxysilane and γ-aminopropylmethyldiethoxysilane in a mass ratio of 1:1) was added to the silicon micropowder according to a mass ratio of silicon micropowder to modifier of 100:2, and the modified product was modified at 110°C and a rotation speed of 1400 rpm for 35 minutes to obtain silicon micropowder.

[0051] Comparative Example 2

[0052] Quartz ore with a silicon content of 99.2% was crushed, washed with water, dried and ground to obtain silicon powder with a particle size of 325 mesh; A grinding aid (prepared by mixing sodium hexametaphosphate, polyethylene glycol, and ammonium lignin sulfonate in a mass ratio of 2:1:1) was added to the silicon powder at a mass ratio of 1000:7, and then ground and classified by a jet mill to obtain silicon micropowder with a particle size of 3000 mesh; The obtained silicon micropowder was soaked and washed with water and then dried at 120°C for 180 minutes. A modifier (obtained by mixing γ-aminopropyltriethoxysilane and γ-aminopropylmethyldiethoxysilane in a mass ratio of 1:1) was added to the soaked and washed silicon micropowder according to a mass ratio of silicon micropowder to modifier of 100:2, and the modified product was subjected to modification at 110°C and a rotation speed of 1400 rpm for 35 minutes to obtain silicon micropowder.

[0053] The performance of the high-purity silicon powder obtained in Examples 1 to 5 and the silicon powder obtained in Comparative Examples 1 to 2 was tested, and the test results are shown in Table 1.

[0054] Table 1 Performance test results of high-purity silicon micropowder obtained in Examples 1 to 5 and silicon micropowder obtained in Comparative Examples 1 to 2

[0055] As can be seen from Table 1, the particle size of the high-purity silicon micropowder obtained in the present invention is D50≤4.5μm, D70≤12.8μm, the oil absorption value is between 23 and 24 mL / 100g, the activation degree is ≥97.5%, and the silicon content is ≥99.7%. It can be seen that the high-purity silicon micropowder obtained in the present invention has excellent particle size, activation degree and silicon content.

[0056] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing high-purity silicon micropowder, characterized in that: The method comprises the following preparation steps: 1) Mixing silicon powder with a grinding aid and grinding to obtain silicon micropowder; 2) reacting the silicon micropowder with the purified solution, and then adding a modifier to modify it to obtain high-purity silicon micropowder; The purification solution in step 2) is obtained by mixing hydrochloric acid, hydrofluoric acid and water.

2. The method for preparing high-purity silicon micropowder according to claim 1, wherein: In the step 1), the particle size of the silicon powder is 300-350 mesh; The silicon powder is obtained by crushing quartz ore, and the silicon content of the quartz ore is ≥99.2%.

3. The method for preparing high-purity silicon micropowder according to claim 2, wherein: In the step 1), the grinding aid is one or more of sodium hexametaphosphate, polyethylene glycol and ammonium lignin sulfonate; The mass ratio of silicon powder to grinding aid is 1000:6~8.

4. The method for preparing high-purity silicon micropowder according to claim 3, wherein: In the step 1), the grinding speed is 25-30 rpm, the grinding time is 2-4 h, the grinding ball-to-material ratio is 45-55:45-55, the grinding medium is ceramic balls, and the diameter of the ceramic balls is 20-40 mm.

5. The method for preparing high-purity silicon micropowder according to claim 3 or 4, characterized in that: In the step 1), the particle size of the silicon micropowder is 2800-3200 mesh.

6. The method for preparing high-purity silicon micropowder according to claim 5, characterized in that: In step 2), the volume ratio of hydrochloric acid, hydrofluoric acid and water in the purified solution is 1:1:4-7; The dosage ratio of silicon micropowder to purification solution is 1g:3~4mL.

7. The method for preparing high-purity silicon micropowder according to claim 6, characterized in that: In the step 2), the reaction time is 2-3 hours, and the reaction temperature is 50-70°C.

8. The method for preparing high-purity silicon micropowder according to claim 6, wherein: In the step 2), the modifier is one or more of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-diethylenetriaminopropyltrimethoxysilane and γ-aminopropylmethyldiethoxysilane; The mass ratio of silicon micropowder to modifier is 100:1~4.

9. The method for preparing high-purity silicon micropowder according to claim 8, characterized in that: In the step 2), the modification time is 30-40 minutes and the modification temperature is 90-120°C; The modification is carried out under stirring at a stirring speed of 1200-1600 rpm.

10. High-purity silicon micropowder obtained by the method for preparing high-purity silicon micropowder according to any one of claims 1 to 9.

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