Preparation method of silica powder

Abstract

The invention discloses a silica powder preparation method, which comprises the following steps: S1, selecting a quartz sand raw material with a silica mass fraction of not less than 99.8%, and carrying out magnetic separation and acid pickling to remove impurities; s2, aging under an alkaline condition, filtering after aging, and dehydrating and drying a filtered substance; s3, adding ethanol and hexamethyldisilazane into the raw materials, atomizing the silane coupling agent hydrolysate by using an atomizer under the atomization pressure of 1.2-1.4 Pa, and mixing the silane coupling agent hydrolysate with the silica powder; s4, carrying out soaking treatment by adopting an organic solvent; and S5, mixing polymethylacrylic acid and ammonium nitrate, performing ultrasonic treatment for 15-30 minutes, performing strong mechanical stirring for 3-5 hours, and performing high-temperature heating treatment. The prepared silica fume has excellent dispersion stability, the silica fume with high hardness is obtained after high-temperature sintering, meanwhile, the silica fume is subjected to carbonization and modification treatment, overall particles are small and high in purity, and the silica fume is good in hardness and high in dispersity.

Description

Technical Field

[0001] The invention relates to the technical field of silicon micropowder, in particular to a method for preparing silicon micropowder. Background Art

[0002] Quartz powder is made of pure quartz (natural quartz or fused quartz) through multiple processes such as crushing, sorting, cleaning, acid treatment, high-temperature melting, medium crushing, fine grinding, grading, and iron removal. It is a powder that meets the use requirements. As an inorganic non-metallic material with good temperature resistance, acid and alkali corrosion resistance, high thermal conductivity, and high insulation, silicon powder is widely used in chemical industry, electronics, integrated circuits, electrical appliances, plastics, coatings, advanced paints, rubber, national defense and other fields. Microsilica powder is a commonly used filler, especially in modern polymer materials such as plastics, rubber, and coatings. With the continuous development of the downstream high-end application market, the quality and stability requirements of non-metallic mineral powder materials are constantly increasing.

[0003] At present, the microsilica powder produced by the existing technology has larger overall particles and the purity is not high enough. In addition, the hardness and dispersibility of the microsilica powder are poor, which affects the quality of products in many application fields. To solve the above problems, we propose a method for preparing silicon micropowder. Summary of the invention

[0004] The present invention provides a method for preparing silicon micropowder in response to the technical deficiencies of the prior art in producing microsilica powder, such as large overall particles of the produced microsilica powder, low purity, high hardness and poor dispersibility, which affect the quality of products in multiple application fields.

[0005] In order to solve the above technical deficiencies, the present invention adopts a modified technical solution, a method for preparing silicon micropowder, comprising the following steps:

[0006] S1, select quartz sand raw material with a silicon dioxide mass fraction of not less than 99.8%, perform magnetic separation, pickling to remove impurities, and then perform wet grinding to obtain grinding slurry, remove iron through magnetic separation, and then naturally precipitate, and then separate the precipitate by mechanical method;

[0007] S2, aging under alkaline conditions, filtering after aging, dehydrating and drying the filtrate, dispersing it into powder or adding a binder to make it into blocks, and then sintering the powder or block quartz ore powder in a high-temperature furnace at 1280-1680°C for 1-10 hours, and then dispersing and grinding it into spheroidization, magnetic separation and air separation classification after cooling to obtain ultrafine spherical silicon powder;

[0008] S3, adding ethanol and hexamethyldisilazide to the raw materials, and atomizing the silane coupling agent hydrolyzate by using an atomizer, with the atomization pressure being 1.2MPa-1.4Pa, and mixing with the silicon micropowder;

[0009] S4, soaking treatment with organic solvent, the treatment time is controlled at 2-4h, the temperature is controlled at 58-96℃, and stirring treatment can be carried out during the soaking process;

[0010] S5, then mix the polymethacrylic acid and ammonium nitrate, firstly subject them to ultrasonic treatment for 15 to 30 minutes, then subject them to strong mechanical stirring for 3 to 5 hours, and then subject them to high temperature heating treatment.

[0011] As a further preferred embodiment of the present invention, in step S1, the pickling process for removing impurities is as follows: the quartz sand particle size is 60 mesh, 80 mesh or 110 mesh, industrial nitric acid is added, the content of nitric acid in the industrial nitric acid is not less than 42%, the nitric acid solution covers the quartz sand, after soaking for 2-6 hours, the acid solution is removed and the quartz sand is repeatedly rinsed with clean water.

[0012] As a further preferred embodiment of the present invention, in step S2, the treatment under alkaline conditions includes the following: adding deionized water to the quartz sand at a solid-liquid ratio of 1:4, cleaning with ultrasound, the frequency of the ultrasound is 50-70KHz, the stirring speed is 200-300r / min, the cleaning time is 2-3h, and then adding sodium bicarbonate, sodium carbonate, and sodium nitrate solutions for soaking for 0.5-1h, soaking in a water bath at 65°C for heating, and finally adding a sodium bicarbonate solution with a mass fraction of 12% and heating in a water bath at 75°C for 1h, with a stirring speed of 400-700r / min.

[0013] As a further preferred embodiment of the present invention, in step S3, an inert gas can be injected during the atomization process, and the inert gas is selected from argon or helium, and the temperature during the atomization process is maintained between 95-120° C. for 0.5-2 h.

[0014] As a further preferred embodiment of the present invention, in step S4, the organic solvent is at least one of diesel, n-butanol, phenylethyl alcohol, liquid paraffin, formaldehyde and methyl ether.

[0015] As a further preferred embodiment of the present invention, in step S5, the high temperature sintering curve is: heating to 1300-1550°C at a heating rate of 2-4.5°C / min and keeping the temperature for 1-3h.

[0016] As a further preferred embodiment of the present invention, in step S5, the ultrasonic process parameters are as follows: the operating frequency is 60-80KHz, the power is 300-2000W; the strong mechanical stirring is: 800-900 rpm.

[0017] As a further preferred embodiment of the present invention, in step S4, physical stirring is adopted, and during the stirring process, the stirring speed is controlled at 720 r / min-1040 r / min.

[0018] The beneficial effects achieved by the present invention are as follows: the microsilica powder produced by the present invention has excellent dispersion stability, and after high-temperature sintering, silicon micropowder with higher hardness is obtained. At the same time, the silicon micropowder is carbonized and modified, and the overall particles are smaller and the purity is high. The microsilica powder also has good hardness and higher dispersibility. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] The present invention provides a technical solution: a method for preparing silicon micropowder, comprising the following steps:

[0021] S1, select quartz sand raw material with a silicon dioxide mass fraction of not less than 99.8%, perform magnetic separation, pickling to remove impurities, and then perform wet grinding to obtain grinding slurry, remove iron through magnetic separation, and then naturally precipitate, and then separate the precipitate by mechanical method;

[0022] S2, aging under alkaline conditions, filtering after aging, dehydrating and drying the filtrate, dispersing it into powder or adding a binder to make it into blocks, and then sintering the powder or block quartz ore powder in a high-temperature furnace at 1280-1680°C for 1-10 hours, and then dispersing and grinding it into spheroidization, magnetic separation and air separation classification after cooling to obtain ultrafine spherical silicon powder;

[0023] S3, adding ethanol and hexamethyldisilazide to the raw materials, and atomizing the silane coupling agent hydrolyzate by using an atomizer, with the atomization pressure being 1.2MPa-1.4Pa, and mixing with the silicon micropowder;

[0024] S4, soaking treatment with organic solvent, the treatment time is controlled at 2-4h, the temperature is controlled at 58-96℃, and stirring treatment can be carried out during the soaking process;

[0025] S5, then mix the polymethacrylic acid and ammonium nitrate, firstly subject them to ultrasonic treatment for 15 to 30 minutes, then subject them to strong mechanical stirring for 3 to 5 hours, and then subject them to high temperature heating treatment.

[0026] In step S1, the pickling process for removing impurities is as follows: the quartz sand particle size is 60 mesh, 80 mesh or 110 mesh, industrial nitric acid is added, the content of nitric acid in the industrial nitric acid is not less than 42%, the nitric acid solution covers the quartz sand, after soaking for 2-6 hours, the acid solution is removed and rinsed repeatedly with clean water, and sufficient pickling treatment can be performed to improve the purity.

[0027] In step S2, the treatment under alkaline conditions includes the following: adding deionized water to the quartz sand at a solid-liquid ratio of 1:4, cleaning with ultrasound, the frequency of the ultrasound is 50-70KHz, the stirring speed is 200-300r / min, the cleaning time is 2-3h, and then adding sodium bicarbonate, sodium carbonate, and sodium nitrate solutions to soak for 0.5-1h, soaking in a water bath at 65°C for heating, and finally adding a sodium bicarbonate solution with a mass fraction of 12% to heat in a water bath at 75°C for 1h, stirring at a speed of 400-700r / min, and selecting sodium bicarbonate, sodium carbonate, and sodium nitrate solutions for mixing to fully wash away excess acid.

[0028] In step S3, an inert gas can be injected during the atomization process. The inert gas is selected from argon or helium, and the temperature during the atomization process is maintained between 95-120° C. for 0.5-2 h. The addition of the inert gas improves the stability of the atomization reaction.

[0029] In step S4, the organic solvent is at least one of diesel, n-butanol, phenylethyl alcohol, liquid paraffin, formaldehyde, and methyl ether.

[0030] In step S5, the high temperature sintering curve is: heating to 1300-1550°C at a heating rate of 2-4.5°C / min, and keeping the temperature for 1-3h to accelerate the uniformity of the temperature rise and make the reaction more stable.

[0031] In step S5, the ultrasonic process parameters are as follows: operating frequency is 60-80KHz, power is 300-2000W; strong mechanical stirring is: 800-900 rpm.

[0032] In step S4, physical stirring is adopted, and during the stirring process, the stirring speed is controlled at 720r / min-1040r / min.

[0033] Embodiment 1

[0034] A method for preparing silicon micropowder comprises the following steps: selecting a quartz sand raw material with a silicon dioxide mass fraction of not less than 99.8% for magnetic separation and pickling to remove impurities, then performing wet grinding, obtaining a grinding slurry for magnetic separation to remove iron and then naturally precipitating, and then separating the precipitate by mechanical method, and the pickling process for removing impurities is as follows: the quartz sand particle size is 60 mesh, 80 mesh or 110 mesh, adding industrial nitric acid, the content of nitric acid in the industrial nitric acid is not less than 42%, the nitric acid solution covers the quartz sand, after soaking for 6 hours, removing the acid solution and rinsing repeatedly with clean water; aging under alkaline conditions, the treatment under alkaline conditions comprises the following steps: After adding deionized water to the quartz sand at a solid-liquid ratio of 1:4, ultrasonic cleaning is performed, the ultrasonic frequency is 70KHz, the stirring speed is 300r / min, and the cleaning time is 3h. Then, sodium bicarbonate, sodium carbonate, and sodium nitrate solutions are added and soaked for 1h, and then heated in a water bath at 65°C. Finally, a sodium bicarbonate solution with a mass fraction of 12% is added and heated in a water bath at 75°C for 1h, and the stirring speed is 700r / min. After aging, the filtrate is filtered, and the filtrate is dehydrated and dried, and then dispersed into powder or added with a binder to form a block. The powdered or block quartz ore powder is then kept in a high-temperature furnace at 1680°C for 10 hours for firing, and after cooling, dispersed grinding, spheroidization, magnetic separation and air separation classification are carried out to obtain ultrafine spherical silicon powder; ethanol and hexamethyldisilazide are added to the raw materials, and the silane coupling agent hydrolyzate is atomized by using an atomizer, and the atomization pressure is 1.4Pa, and mixed with the silicon powder. Inert gas can be injected during the atomization process, and the inert gas is selected from argon or helium. The temperature during the atomization process is maintained at 120°C for 2 hours; an organic solvent is used for immersion treatment, the treatment time is controlled at 4 hours, the temperature is controlled at 96°C, and stirring can be carried out during the immersion process. The solvent is at least one of diesel, n-butanol, phenylethyl alcohol, liquid paraffin, formaldehyde and methyl ether, and physical stirring is adopted. During the stirring process, the stirring speed is controlled at 1040r / min; then polymethyl methacrylate and ammonium nitrate are mixed, and ultrasonic treatment is first performed for 30 minutes. The ultrasonic process parameters are as follows: the working frequency is 80KHz, the power is 2000W; the strong mechanical stirring is: 900 rpm, and then the strong mechanical stirring is performed for 5 hours, and then high-temperature heating treatment is performed. The high-temperature sintering curve is: heating to 1550°C at a heating rate of 4.5°C / min, and keeping warm for 1-3h.

[0035] Embodiment 2

[0036] A method for preparing silicon micropowder comprises the following steps: selecting a quartz sand raw material with a silicon dioxide mass fraction of not less than 99.8% for magnetic separation and pickling to remove impurities, then performing wet grinding, obtaining a grinding slurry for magnetic separation to remove iron, and then naturally precipitating, and then separating the precipitate by mechanical method, and the pickling process for removing impurities is as follows: the quartz sand particle size is 60 mesh, 80 mesh or 110 mesh, adding industrial nitric acid, the content of nitric acid in the industrial nitric acid is not less than 42%, the nitric acid solution covers the quartz sand, soaking for 2 hours, removing the acid solution and rinsing repeatedly with clean water; aging under alkaline conditions, the alkaline treatment comprises the following steps: After adding deionized water according to the solid-liquid ratio of 1:4, ultrasonic cleaning is performed, the ultrasonic frequency is 50KHz, the stirring speed is 200r / min, the cleaning time is 2h, and then sodium bicarbonate, sodium carbonate, and sodium nitrate solutions are added to soak for 0.5h, and then soaked in a water bath at 65°C for heating. Finally, a sodium bicarbonate solution with a mass fraction of 12% is added and heated in a water bath at 75°C for 1h, and the stirring speed is 400r / min. After aging, the filter is filtered, and the filtrate is dehydrated and dried, and then dispersed into powder or added with a binder to make a block, and then the powdered or block quartz ore powder is kept in a high-temperature furnace at 1280°C for 1 hour. The raw materials are sintered, and then dispersed, ground and spheroidized, magnetically separated and air-selected to obtain ultrafine spherical silicon powder. Ethanol and hexamethyldisilazide are added to the raw materials, and the silane coupling agent hydrolyzate is atomized by an atomizer at a pressure of 1.2 MPa, and mixed with the silicon powder. Inert gas can be injected during the atomization process. The inert gas is argon or helium. The temperature during the atomization process is maintained at 95°C for 0.5h. An organic solvent is used for immersion treatment. The treatment time is controlled at 2h and the temperature is controlled at 58°C. Stirring can be performed during the immersion process. The organic solvent is At least one of diesel, n-butanol, phenylethyl alcohol, liquid paraffin, formaldehyde, and dimethyl ether; in step S4, physical stirring is adopted, and during the stirring process, the stirring speed is controlled at 720r / min; then the polymethyl methacrylate and ammonium nitrate are mixed, and ultrasonic treatment is first performed for 15-30 minutes, and the ultrasonic process parameters are as follows: the operating frequency is 60KHz, the power is 300W; the strong mechanical stirring is: 800 rpm, and then the strong mechanical stirring is performed for 3 hours, and then high-temperature heating treatment is performed, and the high-temperature sintering curve is: heating to 1300°C at a heating rate of 2°C / min, and keeping warm for 1-3h.

[0037] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention.

[0038] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing silicon micropowder, characterized in that: The method comprises the following steps: S1, select quartz sand raw material with a silicon dioxide mass fraction of not less than 99.8%, perform magnetic separation, pickling to remove impurities, and then perform wet grinding to obtain grinding slurry, remove iron through magnetic separation, and then naturally precipitate, and then separate the precipitate by mechanical method; S2, aging under alkaline conditions, filtering after aging, dehydrating and drying the filtrate, dispersing it into powder or adding a binder to make it into blocks, and then sintering the powder or block quartz ore powder in a high-temperature furnace at 1280-1680°C for 1-10 hours, and then dispersing and grinding it into spheroidization, magnetic separation and air separation classification after cooling to obtain ultrafine spherical silicon powder; S3, adding ethanol and hexamethyldisilazide to the raw materials, and atomizing the silane coupling agent hydrolyzate by using an atomizer, with the atomization pressure being 1.2MPa-1.4Pa, and mixing with the silicon micropowder; S4, soaking treatment with organic solvent, the treatment time is controlled at 2-4h, the temperature is controlled at 58-96℃, and stirring treatment can be carried out during the soaking process; S5, then mix the polymethacrylic acid and ammonium nitrate, firstly subject them to ultrasonic treatment for 15 to 30 minutes, then subject them to strong mechanical stirring for 3 to 5 hours, and then subject them to high temperature heating treatment.

2. The method for preparing silicon micropowder according to claim 1, characterized in that: In step S1, the pickling process for removing impurities is as follows: the quartz sand particle size is 60 mesh, 80 mesh or 110 mesh, industrial nitric acid is added, the nitric acid content in the industrial nitric acid is not less than 42%, the nitric acid solution covers the quartz sand, after soaking for 2-6 hours, the acid solution is removed and the quartz sand is repeatedly rinsed with clean water.

3. The method for preparing silicon micropowder according to claim 1, characterized in that: In step S2, the treatment under alkaline conditions includes the following: adding deionized water to the quartz sand at a solid-liquid ratio of 1:4, cleaning with ultrasound, the frequency of the ultrasound is 50-70KHz, the stirring speed is 200-300r / min, the cleaning time is 2-3h, and then adding sodium bicarbonate, sodium carbonate, and sodium nitrate solutions to soak for 0.5-1h, soaking in a water bath at 65°C for heating, and finally adding a sodium bicarbonate solution with a mass fraction of 12% and heating in a water bath at 75°C for 1h, with a stirring speed of 400-700r / min.

4. The method for preparing silicon micropowder according to claim 1, characterized in that: In step S3, an inert gas may be injected during the atomization process, wherein the inert gas is selected from argon or helium, and the temperature during the atomization process is maintained between 95-120° C. for 0.5-2 h.

5. The method for preparing silicon micropowder according to claim 1, characterized in that: In step S4, the organic solvent is at least one of diesel, n-butanol, phenylethyl alcohol, liquid paraffin, formaldehyde, and methyl ether.

6. The method for preparing silicon micropowder according to claim 1, characterized in that: In step S5, the high temperature sintering curve is: heating to 1300-1550°C at a heating rate of 2-4.5°C / min and keeping the temperature for 1-3h.

7. The method for preparing silicon micropowder according to claim 1, characterized in that: In step S5, the ultrasonic process parameters are as follows: operating frequency is 60-80KHz, power is 300-2000W; strong mechanical stirring is: 800-900 rpm.

8. The method for preparing silicon micropowder according to claim 1, characterized in that: In step S4, physical stirring is adopted, and during the stirring process, the stirring speed is controlled at 720r / min-1040r / min.