Micron-sized high-purity quartz sand and its preparation process

Abstract

The application belongs to the technical field of quartz sand, and discloses micron-grade high-purity quartz sand and a preparation process thereof. The preparation process comprises the following steps: 1) uniformly mixing ammonia water, deionized water, a beta-dicarbonyl compound, an alcohol surfactant and a quaternary ammonium base to obtain a mixed solution; 2) slowly dropping alkoxysilane into the mixed solution at a hydrolysis temperature to obtain a sol; 3) alcohol removal of the sol by heating until a gel is formed, and then stopping heating and naturally cooling and aging; and 4) calcining the aged gel after freeze-drying to obtain micron-grade high-purity quartz sand. The micron-grade high-purity quartz sand is prepared by using alkoxysilane as a raw material, introducing an additive and controlling process conditions, and quartz sand products with a particle size of 30-600 microns, a specific surface area of <5 m 2 / g, a bulk density of >1.20 g / mL and a purity of >99.999% are obtained, and the quartz sand products have a good industrialization prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of quartz sand, and particularly relates to micron-grade high-purity quartz sand and a preparation process thereof. BACKGROUND

[0002] Quartz is a silicate mineral, which is hard and wear-resistant. When the content of SiO2 is higher than 99.99%, the quartz is called high-purity quartz, which is an irreplaceable key raw material in many technical fields, such as semiconductors, optical communication, photovoltaics, precision optics, and electric light sources. High-purity quartz material is an indispensable strategic resource for the country, and is an important raw material in the fields of national defense and strategic industries.

[0003] Since quartz resources are non-renewable resources, the chemical synthesis method for preparing high-purity quartz has been highly valued at home and abroad. The quartz sand prepared by the common method through alkoxysilane has a particle size of nanometer level, and the product has a rich pore structure and a large specific surface, and a low bulk density, and thus cannot be used as a raw material for processing and preparing high-end quartz products. Therefore, there is a lack of a chemical synthesis method for micron-grade high-purity quartz sand. SUMMARY

[0004] The technical problem to be solved by the application is to provide micron-grade high-purity quartz sand and a preparation process thereof in view of the deficiencies in the prior art. The prepared quartz sand has a particle size of 30-600 microns, a specific surface area of <5 m 2 / g, a bulk density of >1.20 g / mL, and a purity of >99.999%, and can be used for preparing high-end quartz products.

[0005] To solve the technical problem proposed in the application, the application provides a preparation process for micron-grade high-purity quartz sand, which comprises the following steps:

[0006] 1) uniformly mixing ammonia water, deionized water, a beta-dicarbonyl compound, an alcohol surfactant, and a quaternary ammonium base to obtain a mixed solution;

[0007] 2) slowly dropping alkoxysilane into the mixed solution at a hydrolysis temperature to obtain a sol;

[0008] 3) heating the sol to remove alcohol until a gel is formed, stopping heating, and naturally cooling and aging;

[0009] 4) freeze-drying the aged gel and then calcining to obtain micron-grade high-purity quartz sand.

[0010] In the above scheme, the ammonia water is a commercially available electronic-grade product, and has a concentration of 25-28%.

[0011] In the above scheme, the deionized water has a resistivity of >18 MΩ·cm (25℃).

[0012] In the above scheme, the β-dicarbonyl compound is one or more of β-diketone, β-keto ester, malonic acid diester.

[0013] Further, the β-diketone is one or more of acetylacetone, propionylbutanone, butyrylpentanone.

[0014] Further, the β-keto ester is one or more of methyl acetoacetate, ethyl acetoacetate.

[0015] Further, the malonic acid diester is one or more of dimethyl malonate, diethyl malonate.

[0016] In the above scheme, the alcohol surfactant is one or more of polyvinyl alcohol, polyethylene glycol, polypropylene glycol.

[0017] In the above scheme, the quaternary ammonium base is one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide.

[0018] In the above scheme, the alkoxysilane is one or more of tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, methyl triethoxysilane.

[0019] In the above scheme, the amount of each raw material is 0.2-10% of ammonia, 60-85% of deionized water, 0.01-1% of β-dicarbonyl compound, 0.01-1% of alcohol surfactant, 0.01-1% of quaternary ammonium base, and 7-30% of alkoxysilane, with the sum of the above raw materials being 100% by mass.

[0020] In the above scheme, the molar ratio of the alkoxysilane to deionized water is (0.01-0.05):1.

[0021] In the above scheme, the hydrolysis temperature is 0-60℃.

[0022] In the above scheme, the dropping time of the alkoxysilane is 2-20h.

[0023] In the above scheme, the temperature for alcohol removal by heating is 80-150℃.

[0024] In the above scheme, the aging time is 4-96h.

[0025] In the above scheme, the freeze-drying step is: first, freeze at -60 to -40℃ for 2-4h; then, under a vacuum degree of less than 100Pa, dry at -35 to -25℃ for 8-16h; and then, under a vacuum degree of less than 20Pa, dry at 20-60℃ for 6-12h.

[0026] Further, the cooling rate in the freeze-drying process is 0.3-1.5 ℃ / min, the first heating rate is 0.3-1.5 ℃ / min, and the second heating rate is 0.3-1.5 ℃ / min.

[0027] In the above scheme, the step of calcining is: first calcining in an air atmosphere at 600-800 ℃ for 2-24 h, and then calcining in a vacuum atmosphere at 850-1250 ℃ for 4-48 h.

[0028] Further, the vacuum degree of the vacuum atmosphere is less than 100 Pa.

[0029] The application further provides a micron-sized high-purity quartz sand prepared by the above process.

[0030] In the above scheme, the micron-sized high-purity quartz sand has a particle size of 30-600 μm, a specific surface area of <5 m 2 / g, a bulk density of ≥1.20 g / mL, and a purity of ≥99.999%.

[0031] The main technical concept of the application is as follows:

[0032] The application uses alkoxysilane as raw material, ammonia as catalyst, beta-dicarbonyl compound as cocatalyst, alcohol surfactant as dispersant, and quaternary amine base as agglomerating agent to hydrolyze to obtain sol, then alcohol is removed by heating to form gel, the gel is aged, dried and calcined to obtain micron-sized high-purity quartz sand.

[0033] The addition of beta-dicarbonyl compound can reduce the cross-linking chain growth rate of alkoxysilane hydrolysis, increase the hydrolysis rate inside the cross-linked micelle, so that the formed silica sol primary particles are more compact, and the internal wrapped water molecules or organic molecules are avoided, thereby avoiding the formation of pores in subsequent processing to reduce the bulk density or increase the specific surface.

[0034] The addition of alcohol surfactant and quaternary amine base can form micelles inside the reaction system, capture alkoxysilane in the reaction system, increase the reaction rate inside the micelle, and make the generated water timely discharged from the micelle, increase the internal density, and make the generated silica particles more compact. In the process of removing organic matter by heating and distillation, with the discharge of small organic molecules, silica sol particles aggregate with each other to form a gel, and the micelles formed by the alcohol surfactant become the place for the aggregation of nano-silica particles, which can avoid the formation of larger particles, because larger particles will wrap small molecules and bubbles therein, and the particles inside the wrapped body can aggregate more tightly, thereby increasing the primary density of the particles.

[0035] Too high hydrolysis temperature will result in uncontrollable hydrolysis reaction rate, so that the beta-dicarbonyl compound and quaternary ammonium base lose effect, which will result in that the specific surface of finished product greatly increases, the granularity decreases, and the bulk density decreases, therefore, the hydrolysis temperature is controlled to be not more than 60 DEG C in the application.

[0036] If the gel is dried by air blowing heating, residual moisture and organic groups will be wrapped in the particles, which will result in particle puffing and coking in the subsequent calcination process, so that the product will have foaming and carbonization blackening phenomenon, and high-purity quartz sand with micron size cannot be obtained, therefore, freeze drying is adopted in the application, and the process conditions of freeze drying are strictly controlled.

[0037] Compared with the prior art, the application has the following beneficial effects:

[0038] 1) The alkoxysilane is used as raw material in the application, and the preparation of micron high-purity quartz sand is realized through the introduction of additives and the control of process conditions, so that the quartz sand product with a particle size of 30-600 microns, a specific surface area of <5 m 2 / g, a bulk density of >1.20 g / mL, and a purity of >99.999% can be obtained, and the product can be used for preparing high-end quartz products.

[0039] 2) The preparation process of the application is simple, and micron quartz sand particles can be directly obtained after calcination without the crushing process, which greatly reduces the production difficulty, avoids the use of high-cost crushing equipment and the introduction of impurities, and finally the product has very low specific surface area, small amount of gas adsorbed on the surface, and good industrialization prospect. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 The SEM diagram of micron high-purity quartz sand prepared in Example 1 of the application.

[0041] The data and atlas richest example is displayed in the forefront, and Example 6 is proposed as Example 1. DETAILED DESCRIPTION

[0042] In order to better understand the application, the content of the application will be further illustrated in combination with the following examples, but the content of the application is not limited to the following examples.

[0043] In the following examples, the ammonia water used is electronic grade, and the concentration is 25-28%, and the resistivity of the deionized water used is >18 MΩ·cm (25 DEG C).

[0044] In the following examples, the bulk density is measured according to GB / T 21354-2008 "General method for measuring tap density of powder products".

[0045] Example 1

[0046] A preparation process of micron high-purity quartz sand, comprising the following steps:

[0047] 1) The raw materials are weighed according to the following mass percentage: ammonia water 7.22%, deionized water 64.98%, beta-dicarbonyl compound 0.22%, alcohol surfactant 0.02%, quaternary ammonium base 0.08%, alkoxysilane 27.48%;

[0048] The preparation materials are as follows: ammonia water 5000g, deionized water 45000g, acetylacetone 50g, ethyl acetoacetate 50g, dimethyl malonate 50g, polyvinyl alcohol 5g, polyethylene glycol 5g, polypropylene glycol 5g, tetrabutylammonium hydroxide 57g, tetramethoxysilane 19027g;

[0049] The molar ratio of tetramethoxysilane to deionized water is 0.05:1;

[0050] 2) The ammonia water, deionized water, acetylacetone, ethyl acetoacetate, dimethyl malonate, polyvinyl alcohol, polyethylene glycol, polypropylene glycol, and tetrabutylammonium hydroxide are uniformly mixed to obtain a mixed solution;

[0051] 3) The hydrolysis temperature is controlled at 28℃, and the tetramethoxysilane is slowly dropped into the mixed solution, and the dropping is completed in 8h to obtain a sol;

[0052] 4) The sol is heated to 100℃ to remove alcohol until a gel is formed, and the heating is stopped, and the gel is naturally cooled and aged for 48h;

[0053] 5) The aged gel is freeze-dried, and the specific process is: first, under atmospheric pressure, the temperature is lowered to-50℃ at a rate of 0.4℃ / min for 3h; then, under a vacuum degree of less than 100Pa, the temperature is raised to-30℃ at a rate of 1℃ / min for 12h; and then, under a vacuum degree of 12Pa, the temperature is raised to 40℃ at a rate of 1℃ / min for 8h;

[0054] After freeze-drying, the gel is calcined, and the specific process is: first, calcined at 750℃ in air for 12h, and then calcined at 1150℃ in a vacuum atmosphere with a vacuum degree of 50Pa for 6h; 7500g of micron high-purity quartz sand is obtained.

[0055] Figure 1 The SEM image of the micron high-purity quartz sand prepared in this embodiment, from which it can be seen that the particle size of the prepared quartz sand sample reaches micron level.

[0056] The micron high-purity quartz sand prepared in this embodiment has a median particle size D 50 of 410μm, a specific surface area of 1.7m 2 / g, and a bulk density of 1.31g / cm3 99.9993% purity of product.

[0057] Comparative Example 1

[0058] Comparative Example 1 and Example 1 differ only in that no β-dicarbonyl compound, alcohol surfactant and quaternary ammonium base are added, i.e. the raw materials are only ammonia 5000 g, deionized water 45000 g, tetramethoxysilane 19027 g.

[0059] It is detected that the median particle size D 50 of the quartz sand prepared in Comparative Example 1 is 300 nm, the specific surface area is 81.7 m 2 / g, and the bulk density is 0.58 g / cm 3 , and the purity of the product is 99.9992%.

[0060] From the results of Comparative Example 1 and Example 1, it can be seen that the β-dicarbonyl compound, alcohol surfactant and quaternary ammonium base added in the present application play a key role in the particle size, specific surface area and bulk density of the product.

[0061] Example 2

[0062] A preparation process of micron-level high-purity quartz sand, comprising the following steps:

[0063] 1) Weigh the raw materials according to the following mass percentage: ammonia 10%, deionized water 82.91%, β-dicarbonyl compound 0.06%, alcohol surfactant 0.02%, quaternary ammonium base 0.01%, alkoxysilane 7%;

[0064] The preparation conditions are as follows: ammonia 5430 g, deionized water 45000 g, acetylacetone 25 g, ethyl acetoacetate 5 g, polyvinyl alcohol 10 g, tetramethylammonium hydroxide 5.5 g, tetramethoxysilane 3800 g;

[0065] Among them, the molar ratio of tetramethoxysilane to deionized water is 0.01:1;

[0066] 2) Mix the ammonia, deionized water, acetylacetone, ethyl acetoacetate, polyvinyl alcohol and tetramethylammonium hydroxide uniformly to obtain a mixed solution;

[0067] 3) Control the hydrolysis temperature to be 50°C, slowly drop the tetramethoxysilane into the mixed solution, and after 2h of dropping, obtain a sol;

[0068] 4) Heat the sol to 100°C to remove alcohol until a gel is formed, stop heating, and naturally cool and age for 4h;

[0069] 5) the aged gel is freeze-dried by the following process: first, cooling to -40℃ at a rate of 0.4℃ / min under atmospheric pressure for 2 hours; then, drying at a rate of 1℃ / min to -25℃ under a vacuum degree of less than 100Pa for 8 hours; and then, drying at a rate of 1℃ / min to 40℃ under a vacuum degree of 18Pa for 12 hours;

[0070] After freeze-drying, the product is calcined by the following process: first, calcining at 600℃ in an air atmosphere for 2 hours; and then, calcining at 850℃ in a vacuum atmosphere with a vacuum degree of 90Pa for 4 hours; and 1490g of micron-grade high-purity quartz sand is obtained.

[0071] After detection, the micron-grade high-purity quartz sand prepared in this embodiment has a median particle size D 50 of 50μm, a specific surface area of 4.2m 2 / g, a bulk density of 1.20g / cm 3 , and a product purity of 99.9992%.

[0072] Example 3

[0073] A preparation process of micron-grade high-purity quartz sand, comprising the following steps:

[0074] 1) each raw material is weighed according to the following mass percentage: ammonia water 0.2%, deionized water 69.22%, β-dicarbonyl compound 0.01%, alcohol surfactant 0.12%, quaternary ammonium base 0.45%, and alkoxysilane 30%;

[0075] The preparation materials are as follows: ammonia water 130g, deionized water 45000g, methyl acetoacetate 6.5g, polyethylene glycol 80g, tetrapropylammonium hydroxide 292g, and tetraethoxysilane 19500g;

[0076] The molar ratio of tetraethoxysilane to deionized water is 0.037:1;

[0077] 2) the ammonia water, deionized water, methyl acetoacetate, polyethylene glycol, and tetrapropylammonium hydroxide are mixed uniformly to obtain a mixed solution;

[0078] 3) the hydrolysis temperature is controlled at 60℃, and the tetraethoxysilane is slowly dropped into the mixed solution, and the dropping is completed in 8h to obtain a sol;

[0079] 4) the sol is heated to 120℃ to remove alcohol until a gel is formed, heating is stopped, and natural cooling is performed for 8h;

[0080] 5) the aged gel is freeze-dried by the following process: first, cooling to -60℃ at a rate of 0.4℃ / min under atmospheric pressure for 4 hours; then, drying at a rate of 1℃ / min to -35℃ under a vacuum degree of less than 100Pa for 16 hours; and then, drying at a rate of 1℃ / min to 20℃ under a vacuum degree of 10Pa for 12 hours;

[0081] After freeze-drying, the product is calcined by the following process: first, calcining at 750℃ in an air atmosphere for 2 hours; and then, calcining at 900℃ in a vacuum atmosphere with a vacuum degree of 50Pa for 6 hours; and 5600g of micron-grade high-purity quartz sand is obtained.

[0082] After detection, the micron-grade high-purity quartz sand prepared in this embodiment has a median particle size D 50 of 30μm, a specific surface area of 4.5m 2 / g, a bulk density of 1.20g / cm 3 , and a product purity of 99.9991%.

[0083] Example 4

[0084] A preparation process of micron-grade high-purity quartz sand, comprising the following steps:

[0085] 1) each raw material is weighed according to the following mass percentage: ammonia water 4.88%, deionized water 73.13%, β-dicarbonyl compound 1%, alcohol surfactant 0.53%, quaternary ammonium base 0.8%, and alkoxysilane 19.66%;

[0086] The preparation materials are as follows: ammonia water 3000g, deionized water 45000g, ethyl acetoacetate 400g, dimethyl malonate 216g, polypropylene glycol 325g, tetraethylammonium hydroxide 492g, and tetrapropoxysilane 12100g;

[0087] The molar ratio of tetrapropoxysilane to deionized water is 0.018:1;

[0088] 2) the ammonia water, deionized water, ethyl acetoacetate, dimethyl malonate, polypropylene glycol, and tetraethylammonium hydroxide are mixed uniformly to obtain a mixed solution;

[0089] 3) the hydrolysis temperature is controlled at 45℃, and the tetrapropoxysilane is slowly dropped into the mixed solution, and the dropping is completed in 10h to obtain a sol;

[0090] 4) the sol is heated to 150℃ to remove alcohol until a gel is formed, heating is stopped, and natural cooling is performed for 96h;

[0091] 5) the aged gel is freeze-dried by the following process: first, cooling to -50℃ at a rate of 0.4℃ / min under atmospheric pressure for 4 hours; then, drying at a rate of 1℃ / min to -30℃ under a vacuum degree of less than 100Pa for 16 hours; and then, drying at a rate of 1℃ / min to 40℃ under a vacuum degree of 10Pa for 8 hours;

[0092] After freeze-drying, the product is calcined by the following process: first, calcining at 800℃ in an air atmosphere for 24 hours; and then, calcining at 1000℃ in a vacuum atmosphere with a vacuum degree of 10Pa for 48 hours; and 2720g of micron-grade high-purity quartz sand is obtained.

[0093] After detection, the micron-grade high-purity quartz sand prepared in this embodiment has a median particle size D 50 of 118μm, a specific surface area of 3.5m 2 / g, a bulk density of 1.22g / cm 3 , and a product purity of 99.9993%.

[0094] Example 5

[0095] A preparation process of micron-grade high-purity quartz sand, comprising the following steps:

[0096] 1) each raw material is weighed according to the following mass percentage: ammonia water 7.3%, deionized water 65.73%, β-dicarbonyl compound 0.26%, alcohol surfactant 1%, quaternary ammonium base 0.15%, and alkoxysilane 25.56%;

[0097] The preparation materials are as follows: ammonia water 10000g, deionized water 90000g, acetylacetone 100g, dimethyl malonate 250g, polyvinyl alcohol 1370g, tetrabutylammonium hydroxide 205g, and methyl triethoxysilane 35000g;

[0098] The molar ratio of methyl triethoxysilane to deionized water is 0.039:1;

[0099] 2) the ammonia water, deionized water, acetylacetone, dimethyl malonate, polyvinyl alcohol, and tetrabutylammonium hydroxide are uniformly mixed to obtain a mixed solution;

[0100] 3) the hydrolysis temperature is controlled at 0℃, and the methyl triethoxysilane is slowly dropped into the mixed solution, and the dropping is completed in 8h to obtain a sol;

[0101] 4) the sol is heated to 80℃ to remove alcohol until a gel is formed, heating is stopped, and natural cooling is performed for 48h;

[0102] 5) the aged gel is freeze-dried by the following process: first, cooling to -50℃ at a rate of 0.4℃ / min under atmospheric pressure for 4 hours; then, drying at a rate of 1℃ / min to -30℃ under a vacuum degree of less than 100Pa for 16 hours; and then, drying at a rate of 1℃ / min to 40℃ under a vacuum degree of 10Pa for 8 hours;

[0103] After freeze-drying, the product is calcined by the following process: first, calcining at 750℃ in an air atmosphere for 12 hours; and then, calcining at 1250℃ in a vacuum atmosphere with a vacuum degree of 2Pa for 6 hours; and then, obtaining 11720g of micron-grade high-purity quartz sand.

[0104] After detection, the micron-grade high-purity quartz sand prepared in this embodiment has a median particle size D 50 = of 144μm, a specific surface area of 2.9m 2 / g, a bulk density of 1.23g / cm 3 , and a product purity of 99.9991%.

[0105] Example 6

[0106] A preparation process of micron-grade high-purity quartz sand, comprising the following steps:

[0107] 1) weighing each raw material according to the following mass percentage: ammonia water 4.47%, deionized water 67.04%, β-dicarbonyl compound 0.37%, alcohol surfactant 0.3%, quaternary ammonium base 1%, and alkoxy silane 26.82%;

[0108] The preparation materials are as follows: ammonia water 3000g, deionized water 45000g, dimethyl malonate 250g, polyvinyl alcohol 200g, tetrabutylammonium hydroxide 671g, and tetramethoxysilane 18000g;

[0109] The molar ratio of methyltriethoxysilane to deionized water is 0.047:1;

[0110] 2) mixing the ammonia water, deionized water, dimethyl malonate, polyvinyl alcohol, and tetrabutylammonium hydroxide uniformly to obtain a mixed solution;

[0111] 3) controlling the hydrolysis temperature to be 45℃, and slowly dropping the tetramethoxysilane into the mixed solution, which is completed in 8h to obtain a sol;

[0112] 4) heating the sol to 80℃ to remove alcohol until a gel is formed, stopping heating, and naturally cooling and aging for 48h;

[0113] 5) The aged gel is freeze-dried in the following way: first, it is cooled to -50°C at a rate of 0.4°C / min under atmospheric pressure for 4 hours; then, it is dried at a rate of 1°C / min to -30°C under a vacuum of less than 100 Pa for 16 hours; and finally, it is dried at a rate of 1°C / min to 40°C under a vacuum of 10 Pa for 8 hours;

[0114] After freeze-drying, the product is calcined in the following way: first, it is calcined at 750°C in an air atmosphere for 12 hours, and then it is calcined at 1150°C in a vacuum atmosphere of 2 Pa for 6 hours; 7060 g of micron-grade high-purity quartz sand is obtained.

[0115] After detection, the micron-grade high-purity quartz sand prepared in this embodiment has a median particle size D 50 of 247 μm, a specific surface area of 2.4 m 2 / g, a bulk density of 1.28 g / cm 3 , and a product purity of 99.9991%.

[0116] The above examples are merely illustrative and are not intended to limit the embodiments. Based on the above description, other different forms of changes or variations can be made by those of ordinary skill in the art, and it is not necessary or possible to exhaust all the embodiments. Therefore, obvious changes or variations still fall within the protection scope of the present application.

Claims

1. A process for the production of micron-sized high purity quartz sand, characterized in that, The method comprises the following steps: 1) mixing ammonia water, deionized water, a β-dicarbonyl compound, an alcohol surfactant and a quaternary ammonium base uniformly to obtain a mixed solution; the amount of each raw material is 0.2-10% of ammonia water, 60-85% of deionized water, 0.01-1% of the β-dicarbonyl compound, 0.01-1% of the alcohol surfactant, 0.01-1% of the quaternary ammonium base and 7-30% of the alkoxysilane, with the total being 100%; the β-dicarbonyl compound is one or more of a β-diketone, a β-keto ester and a malonic acid diester; the quaternary ammonium base is one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide; 2) slowly dropping the alkoxysilane into the mixed solution at a hydrolysis temperature to obtain a sol; 3) heating the sol to remove alcohol until a gel is formed, stopping heating and naturally cooling and aging; 4) freeze-drying and calcining the aged gel to obtain micron-sized high-purity quartz sand.

2. The process for preparing micro-sized high purity quartz sand according to claim 1, characterized in that, The alkoxysilane is one or more of tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane and methyl triethoxysilane.

3. The process for preparing micro-sized high purity quartz sand according to claim 1, characterized in that, The alcohol surfactant is one or more of polyvinyl alcohol, polyethylene glycol and polypropylene glycol.

4. The process for preparing micro-sized high purity quartz sand according to claim 1, characterized in that, The ammonia water is electronic-grade ammonia water with a concentration of 25-28%; the deionized water has a resistivity of >18 MΩ·cm.

5. The process for preparing micro-sized high purity quartz sand according to claim 1, characterized in that, The molar ratio of the alkoxysilane to the deionized water is (0.01-0.05):

1.

6. The process for preparing micro-sized high purity quartz sand according to claim 1, characterized in that, The hydrolysis temperature is 0-60°C; the dropping time of the alkoxysilane is 2-20 h; the alcohol removal temperature is 80-150°C; and the aging time is 4-96 h.

7. The process for preparing micro-sized high purity quartz sand according to claim 1, characterized in that, The freeze-drying step is: first freezing at -60 to -40°C for 2-4 h; then drying at -35 to -25°C under a vacuum degree of less than 100 Pa for 8-16 h; and then drying at 20-60°C under a vacuum degree of less than 20 Pa for 6-12 h.

8. The process for preparing micro-sized high purity quartz sand according to claim 1, characterized in that, The calcining step is: first calcining at 600-800°C in an air atmosphere for 2-24 h, and then calcining at 850-1250°C in a vacuum atmosphere for 4-48 h.

9. The micro-sized high-purity quartz sand prepared by the preparation process according to any one of claims 1-8, characterized in that, The micrometer-sized high-purity quartz sand has a particle size of 30-600 μm, a specific surface area of <5 m 2 / g, a bulk density of ≥1.20 g / mL, and a purity of ≥99.999%.

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