Preparation method of high-performance superfine silica powder

Abstract

The invention provides a preparation method of high-performance superfine silica powder, and belongs to the technical field of silica powder preparation. According to the method, quartz stone raw ore is crushed and then sequentially subjected to acid pickling soaking, water washing and drying, and crushed quartz stone particles are obtained; sequentially carrying out primary crushing, secondary crushing and grinding treatment on the crushed quartz stone particles to obtain silica powder; magnetic iron impurities in the silica powder are separated out through magnetic separation, and then ring roller milling and surface modification treatment are sequentially carried out to obtain the high-performance superfine silica powder. The particle size distribution of the superfine silica powder prepared by the method is concentrated at 4-6 microns, the particle size distribution is uniform, and the performance stability of the product is favorably improved.

Description

Technical Field

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

[0002] Silica micropowder is a non-toxic, odorless, and pollution-free inorganic non-metallic material. Due to its excellent properties such as high insulation, high thermal conductivity, and low expansion coefficient, it is widely used in many fields such as electronic packaging, coatings, rubber, and plastics. At present, the existing methods for preparing silicon micropowder have certain limitations in terms of product purity, uniformity of particle size distribution, and production efficiency. Although the traditional mechanical pulverization method has simple equipment and low cost, it is difficult to obtain silicon micropowder with fine and uniform particle size, and impurities are easily introduced during the pulverization process, affecting product performance. Although the chemical synthesis method can produce high-purity and uniform particle size silicon micropowder, the process is complicated and the cost is high, which is not conducive to large-scale industrial production. Therefore, it is of great practical significance to develop a preparation method that can not only ensure the high performance of silicon micropowder, but also achieve efficient and low-cost production. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for preparing high-performance ultrafine silicon micropowder, so as to solve the technical problems of low product purity, uneven particle size distribution and low production efficiency in existing methods for preparing silicon micropowder.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a method for preparing high-performance ultrafine silicon powder, comprising the following steps:

[0006] 1) After crushing the quartz ore, the quartz ore is sequentially pickled, soaked, washed and dried to obtain quartz crushed particles;

[0007] 2) performing a first crushing, a second crushing and a grinding process on the quartz stone particles in sequence to obtain silicon micropowder;

[0008] 3) Separating the magnetic iron impurities in the silicon micropowder by magnetic separation, followed by roller milling and surface modification treatment to obtain a high-performance ultrafine silicon micropowder;

[0009] The surface modification treatment is performed by adding a silane coupling agent.

[0010] Furthermore, the acid concentration of the pickling immersion is 5 to 10 wt %, and the immersion time is 2 to 4 hours.

[0011] Furthermore, the first crushing is carried out in a jaw crusher, and the second crushing is carried out in a hammer crusher, and the second crushing is carried out to a particle size of the quartz stone of 0.1 to 0.5 mm.

[0012] Furthermore, the particle size of the silicon micropowder after the grinding treatment is 300-325 meshes.

[0013] Furthermore, the number of magnetic separations is ≥3 times, and the magnetic field strength of the magnetic separation is 800-1600 Gs.

[0014] Furthermore, a grinding aid is added during the roller milling process, wherein the grinding aid comprises one or more of triethanolamine, sodium polyacrylate and polyacrylic acid amine, and the amount of the grinding aid added is 5-7‰ of the mass of the silicon micropowder.

[0015] Furthermore, the ring roller mill is carried out in a ball mill with a rotation speed of 20-30 r / min, the grinding medium is zirconia balls, the filling ratio of zirconia balls in the ball mill is 30-50%, the feed rate is 8-10 t / h, and the classifying wheel rotation speed is 6000-8000 rpm.

[0016] Furthermore, the silane coupling agent comprises one or more of γ-aminopropyltriethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropylmethyldimethoxysilane and γ-glycidoxypropyltrimethoxysilane, and the addition amount of the silane coupling agent is 1-2% of the mass of the silicon powder.

[0017] Furthermore, the surface modification treatment is carried out at a temperature of 80 to 120° C., and the surface modification treatment is carried out under stirring, with a stirring speed of 1200 to 1800 r / min and a stirring time of 20 to 40 min.

[0018] Beneficial effects of the present invention:

[0019] (1) High purity: Through multiple processes such as hydrochloric acid soaking and magnetic separation to remove iron, the impurities in the raw materials are effectively removed, making the purity of the prepared silicon micropowder as high as 99.9% or more, meeting the strict requirements of high-end fields for the purity of silicon micropowder.

[0020] (2) Uniform particle size distribution: The ball mill is combined with precise process parameter control and air classifier for classification, so that the particle size distribution of the prepared ultrafine silicon micropowder is concentrated in 4-6μm, and the particle size distribution is uniform, which is conducive to improving the performance stability of the product.

[0021] (3) High production efficiency: The preparation method of the present invention has a relatively simple process flow, and the various steps are closely connected, which can realize continuous production, effectively improve production efficiency, reduce production costs, and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a preparation flow chart of the present invention;

[0023] Figure 2 This is an electron microscope image magnified 5000 times of the high-performance ultrafine silicon powder obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] The present invention provides a method for preparing high-performance ultrafine silicon powder, comprising the following steps:

[0025] 1) After crushing the quartz ore, the quartz ore is sequentially pickled, soaked, washed and dried to obtain quartz crushed particles;

[0026] 2) performing a first crushing, a second crushing and a grinding process on the quartz stone particles in sequence to obtain silicon micropowder;

[0027] 3) Separating the magnetic iron impurities in the silicon micropowder by magnetic separation, followed by roller milling and surface modification treatment to obtain a high-performance ultrafine silicon micropowder;

[0028] The surface modification treatment is performed by adding a silane coupling agent.

[0029] In the present invention, the concentration of the acid solution for pickling and soaking is 5-10 wt%, preferably 6-9 wt%, and more preferably 7-8 wt%; the soaking time is 2-4 h, preferably 3 h.

[0030] In the present invention, the purpose of the pickling and soaking is to remove impurities such as metal oxides on the surface of the quartz ore. The drying temperature is 100-120° C., preferably 110° C.; the drying time is 2-3 hours, preferably 2 hours.

[0031] In the present invention, the first crushing is carried out in a jaw crusher, and the second crushing is carried out in a hammer crusher. The second crushing is carried out to a particle size of the quartz stone of 0.1 to 0.5 mm, preferably 0.2 to 0.04 mm.

[0032] In the present invention, the particle size of the silicon micropowder after the grinding treatment is 300-325 mesh, preferably 325 mesh.

[0033] In the present invention, the number of magnetic separations is ≥ 3 times, preferably 3 to 6 times; the magnetic field strength of the magnetic separation is 800 to 1600 Gs, preferably 1000 to 1500 Gs, and more preferably 1100 to 1400 Gs.

[0034] In the present invention, after magnetic separation, the iron content in the silicon powder is reduced to below 0.01 wt%.

[0035] In the present invention, a grinding aid is added during the ring roller grinding process, and the grinding aid comprises one or more of triethanolamine, sodium polyacrylate and polyacrylic acid amine, preferably triethanolamine; the addition amount of the grinding aid is 5-7‰ of the mass of the silicon micropowder, preferably 6‰.

[0036] In the present invention, the ring roller mill is carried out in a ball mill at a rotation speed of 20 to 30 r / min, preferably 25 r / min; the grinding medium is zirconia balls, and the filling ratio of zirconia balls in the ball mill is 30 to 50%, preferably 35 to 45%, and more preferably 40%; the feed rate is 8 to 10 t / h, preferably 9 t / h; the classifying wheel speed is 6000 to 8000 rpm, preferably 7000 rpm.

[0037] In the present invention, the silane coupling agent comprises one or more of γ-aminopropyltriethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropylmethyldimethoxysilane and γ-glycidoxypropyltrimethoxysilane, preferably γ-aminopropyltriethoxysilane; the addition amount of the silane coupling agent is 1 to 2% of the mass of the silicon micropowder, preferably 1.2 to 1.8%, and more preferably 1.4 to 1.6%.

[0038] In the present invention, the temperature of the surface modification treatment is 80-120°C, preferably 90-110°C, and more preferably 100°C; the surface modification treatment is carried out under stirring, and the stirring speed is 1200-1800 r / min, preferably 1300-1600 r / min, and more preferably 1400-1500 r / min; the stirring time is 20-40 min, preferably 30 min.

[0039] In the present invention, the silane coupling agent is uniformly coated on the surface of the silicon micropowder through surface modification treatment, thereby improving the dispersibility of the silicon micropowder and the compatibility with the organic matrix.

[0040] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0041] Example 1

[0042] Select high-quality natural quartz stone ore, crush it to a particle size of less than 5cm, soak it in a 6wt% acid solution for 4 hours to remove impurities such as metal oxides on the surface, rinse it repeatedly with deionized water until it is neutral, and then dry it in an oven at 110℃ for 3 hours. Then use a jaw crusher and a hammer crusher to crush the dried quartz stone into a coarse powder of 0.1-0.5mm, and then grind and grade it with a ring roller mill to obtain 325-mesh silicon micropowder. After three magnetic separations, the magnetic field strength of the magnetic separator is controlled at 1000Gs to reduce the iron content in the coarse powder to below 0.01wt%. The silicon micropowder after magnetic separation is sent to a ball mill for ultrafine grinding. During the grinding process, The grinding aid triethanolamine is 5‰ of the powder mass, the ball mill speed is controlled at 24r / min, the grinding medium is zirconia ball, the filling ratio of zirconia ball in the ball mill is 35%, the feed rate is 10t / h, and the classifying wheel speed is 6000rpm. Ultrafine silicon micropowder with a particle size D97 of 5.6μm is obtained, and then the ultrafine silicon micropowder is placed in a high-speed mixer, and a composite coupling agent of γ-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane accounting for 1% of the mass of the silicon micropowder is added, and the mass ratio of the two is 2:1. The surface modification is carried out by stirring for 30min at a temperature of 90℃ and a speed of 1200r / min, and finally a high-performance ultrafine silicon micropowder is obtained.

[0043] Example 2

[0044] Select high-quality natural quartz stone ore and crush it to a particle size of less than 5cm. Then soak it in an acid solution with a concentration of 8wt% for 3 hours to remove impurities such as metal oxides on the surface. After soaking, rinse it repeatedly with deionized water until it is neutral, and then dry it in an oven at 110℃ for 2 hours. Then use a jaw crusher and a hammer crusher to crush the dried quartz stone into a coarse powder of 0.1-0.5mm. Then, grind and grade it with a ring roller mill to obtain 325-mesh silicon micropowder. After 4 magnetic separations, the magnetic field strength of the magnetic separator is controlled at 1200Gs to reduce the iron content in the coarse powder to below 0.01wt%. The silicon micropowder after magnetic separation is sent to a ball mill for ultrafine grinding. During the grinding process, it is added as a powder. The grinding aid sodium polyacrylate was added in an amount of 6‰, the ball mill speed was controlled at 26r / min, the grinding medium was zirconia balls, the filling ratio of zirconia balls in the ball mill was 40%, the feed rate was 9t / h, the classifying wheel speed was 7000rpm, and ultrafine silicon micropowder with a particle size D97 of 4.8μm was obtained. The ultrafine silicon micropowder was then placed in a high-speed blender, and a composite coupling agent of γ-aminopropylmethyldimethoxysilane and γ-glycidyloxypropyltrimethoxysilane accounting for 1.2% of the mass of the silicon micropowder was added in a mass ratio of 2:1. The surface was modified by stirring for 35min at a temperature of 100℃ and a speed of 1400r / min, and finally a high-performance ultrafine silicon micropowder was obtained.

[0045] Example 3

[0046] Select high-quality natural quartz stone ore and crush it to a particle size of less than 5cm. Then soak it in a 10wt% acid solution for 2 hours to remove impurities such as metal oxides on the surface. After soaking, rinse it repeatedly with deionized water until it is neutral, and then dry it in a 110℃ oven for 2 hours. Then use a jaw crusher and a hammer crusher to crush the dried quartz stone into a coarse powder of 0.1-0.5mm. Then, grind and grade it with a ring roller mill to obtain 325-mesh silicon micropowder. After 5 magnetic separations, the magnetic field strength of the magnetic separator is controlled at 1400Gs to reduce the iron content in the coarse powder to below 0.01wt%. The silicon micropowder after magnetic separation is sent to a ball mill for ultrafine grinding. During the grinding process, it is added as powder. The grinding aid polyacrylic acid amine is 7‰ of the mass, the ball mill speed is controlled at 28r / min, the grinding medium is zirconia ball, the filling ratio of zirconia ball in the ball mill is 45%, the feed rate is 8t / h, and the classification wheel speed is 8000rpm. Ultrafine silicon micropowder with a particle size D97 of 4.3μm is obtained, and then the ultrafine silicon micropowder is put into a high-speed mixer, and a composite coupling agent of γ-aminopropylmethyldiethoxysilane and γ-glycidyloxypropyltrimethoxysilane accounting for 1.4% of the mass of the silicon micropowder is added, and the mass ratio of the two is 2:1. The surface modification is carried out by stirring for 40min at a temperature of 110℃ and a speed of 1600r / min, and finally a high-performance ultrafine silicon micropowder is obtained.

[0047] The properties of the ultrafine silicon powder obtained in Examples 1 to 3 were tested, and the results are shown in Table 1 below.

[0048] Table 1 Performance indicators of high performance ultrafine silicon powder

[0049]

[0050]

[0051] As can be seen from the above examples, the present invention provides a method for preparing high-performance ultrafine silicon micropowder. As can be seen from the above examples, the high-performance silicon micropowder preparation method of the present invention can stably produce high-purity, fine-particle-size, and uniformly distributed silicon micropowder products, and the production process is efficient and cost-controllable, showing good application prospects.

[0052] 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-performance ultrafine silicon powder, characterized in that: The following steps are involved: 1) After crushing the quartz ore, the quartz ore is sequentially pickled, soaked, washed and dried to obtain quartz crushed particles; 2) performing a first crushing, a second crushing and a grinding process on the quartz stone particles in sequence to obtain silicon micropowder; 3) Separating the magnetic iron impurities in the silicon micropowder by magnetic separation, followed by roller milling and surface modification treatment to obtain a high-performance ultrafine silicon micropowder; The surface modification treatment is performed by adding a silane coupling agent.

2. The method for preparing high-performance ultrafine silicon powder according to claim 1, characterized in that: The acid solution concentration of the pickling soaking is 5 to 10 wt %, and the soaking time is 2 to 4 hours.

3. The method for preparing high-performance ultrafine silicon powder according to claim 1 or 2, characterized in that: The first crushing is carried out in a jaw crusher, and the second crushing is carried out in a hammer crusher. The second crushing is carried out to a particle size of the quartz stone of 0.1 to 0.5 mm.

4. The method for preparing high-performance ultrafine silicon powder according to claim 1, characterized in that: The particle size of the silicon micropowder after the grinding treatment is 300-325 meshes.

5. The method for preparing high-performance ultrafine silicon powder according to claim 1, 2 or 4, characterized in that: The number of magnetic separations is ≥3 times, and the magnetic field strength of the magnetic separation is 800-1600 Gs.

6. The method for preparing high-performance ultrafine silicon powder according to claim 5, characterized in that: During the roller milling process, a grinding aid is added, wherein the grinding aid comprises one or more of triethanolamine, sodium polyacrylate and polyacrylic acid amine, and the amount of the grinding aid added is 5-7‰ of the mass of the silicon micropowder.

7. The method for preparing high-performance ultrafine silicon powder according to claim 1 or 6, characterized in that: The ring roller mill is carried out in a ball mill with a rotation speed of 20-30 r / min, the grinding medium is zirconia balls, the filling ratio of zirconia balls in the ball mill is 30-50%, the feed speed is 8-10 t / h, and the classifying wheel rotation speed is 6000-8000 rpm.

8. The method for preparing high-performance ultrafine silicon powder according to claim 7, characterized in that: The silane coupling agent comprises one or more of γ-aminopropyltriethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropylmethyldimethoxysilane and γ-glycidyloxypropyltrimethoxysilane, and the addition amount of the silane coupling agent is 1-2% of the mass of the silicon powder.

9. The method for preparing high-performance ultrafine silicon powder according to claim 8, characterized in that: The surface modification treatment is performed at a temperature of 80 to 120° C., and the surface modification treatment is performed under stirring. The stirring speed is 1200 to 1800 r / min, and the stirring time is 20 to 40 minutes.

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