Preparation method of quartz sand

Abstract

The invention discloses a preparation method of quartz sand. The preparation method comprises the following steps: mixing SiO2 particles with resin to obtain a mixture; heating and curing the mixture; calcining the cured solid to remove the resin and obtain a silicon dioxide block; and crushing the large silicon dioxide blocks to obtain quartz sand with the particle size of 50-300 [mu] m, wherein the particle size of the SiO2 particles ranges from 100 nm to 20 microns, and the porosity of the SiO2 particles ranges from 5% to 8%; the mass ratio of the SiO2 particles to the resin is (10-16): 1. According to the method, small-particle-size SiO2 which is easy to obtain in reality is used as a raw material, resin is added for fixation, calcination is performed to obtain a pure silicon dioxide block, and then the pure silicon dioxide block is crushed to obtain a quartz sand product. The method does not generate pollutants, is green and environment-friendly, can ensure the high purity of the final product by adopting high-purity raw materials, is simple to control, and can effectively solve the problems in the prior art.

Description

Technical Field

[0001] This invention relates to the field of chemical production technology, specifically to a method for preparing quartz sand. Background Technology

[0002] High-purity quartz sand refers to quartz powder with a silica purity greater than 99.99%. It is a major raw material for manufacturing quartz glass, quartz crucibles, quartz tubes, and other products. It is also a high-quality inorganic filler widely used in plastics, rubber, coatings, electronics, and high-tech semiconductors. Currently, the production of high-purity quartz sand mainly involves the mechanical crushing and purification of high-purity quartz ore. However, high-purity quartz ore is a rare mineral, and China's domestic demand for high-purity quartz ore is basically dependent on imports. This strategic resource is easily restricted, and global reserves of high-purity quartz ore are gradually depleting.

[0003] The chemical synthesis of high-purity quartz powder is gaining increasing attention, with common methods including gas-phase and liquid-phase methods. Gas-phase methods produce quartz powders with small particle size, a tendency to agglomerate, and large specific surface area, failing to meet the processing requirements of quartz products. Liquid-phase methods, including sol-gel, microemulsion, and sedimentation processes, produce high-purity quartz powders with high purity, customizable composition, and easily controllable particle size, making them a major research direction for future high-purity quartz sand preparation. However, existing liquid-phase methods for preparing high-purity quartz sand suffer from high raw material costs, complex processes, and significant pollution, necessitating the development of a simple, efficient, low-cost, and environmentally friendly new method. Summary of the Invention

[0004] This invention provides a simple, efficient, low-cost, and environmentally friendly method for preparing quartz sand.

[0005] The present invention provides a method for preparing quartz sand, comprising: mixing SiO2 particles with resin to obtain a mixture; heating and curing the mixture; calcining the cured solid to remove the resin and obtain silica lumps; and crushing the silica lumps to obtain quartz sand with a particle size distribution between 50-300 μm; wherein the particle size distribution of the SiO2 particles is between 100 nm and 20 μm, and the porosity of the SiO2 particles is 5%-8%; the mass ratio of the SiO2 particles to the resin is (10-16):1.

[0006] According to one embodiment of the present invention, the resin is a thermosetting resin that does not contain metal elements, N and S elements.

[0007] According to another embodiment of the present invention, the resin is one or more selected from epoxy resin, phenolic resin, silicone resin, methacrylic resin and polybutadiene resin.

[0008] According to another embodiment of the present invention, the curing is performed in a vacuum environment at a temperature of 80-150°C for 6-8 hours.

[0009] According to another embodiment of the present invention, when the resin is epoxy resin, the curing temperature is 80-120°C and the curing time is 6-8 hours; when the resin is methacrylic resin, the curing temperature is 120-150°C and the curing time is 1-4 hours.

[0010] According to another embodiment of the present invention, the calcination is first heated to 500-800°C and held at that temperature for a certain period of time to remove the resin; then, the temperature is raised to above 1000°C and held at that temperature for 2-20 hours.

[0011] According to another embodiment of the present invention, the purity of the SiO2 particles is 99.9999% or higher.

[0012] According to another embodiment of the present invention, the SiO2 particles are spherical or near-spherical.

[0013] This invention uses readily available small-particle-size SiO2 as raw material, fixes it with resin, calcines it to obtain pure silica blocks, and then crushes them to obtain quartz sand. This method does not produce pollutants, is environmentally friendly, and ensures the high purity of the final product by using high-purity raw materials. It is simple to control and effectively solves the problems existing in the prior art. Detailed Implementation

[0014] To make the present invention clearer and easier to understand, the technical solution of the present invention will be further described below with reference to specific embodiments. The embodiments described below are only used to explain the present invention and are not intended to limit the present invention in any form or substance.

[0015] The method for preparing quartz sand according to the present invention includes: mixing SiO2 particles with resin to obtain a mixture; heating and curing the mixture; calcining the cured solid to remove the resin and obtain silica lumps; and crushing the silica lumps to obtain quartz sand with a particle size distribution between 50-300 μm; wherein the particle size distribution of SiO2 particles is between 100 nm and 20 μm, and the porosity of SiO2 particles is 5%-8%; the mass ratio of SiO2 particles to resin is (10-16):1. The preparation method of the present invention uses SiO2 particles with a particle size distribution within a specific range and a porosity within a certain range as raw materials. These particles are mixed with resin at a specific mass ratio, and heated to fill the gaps between the SiO2 particles. After curing, the resin binds the SiO2 particles into lumps. A calcination step is then performed to remove the resin. Due to the small amount of resin, the SiO2 particles remain in close contact after resin removal. At high temperature, the SiO2 particles soften and liquefy, ultimately forming a single mass. Finally, the quartz sand is obtained by crushing. The method of this invention achieves a SiO2 particle porosity of 5%-8% through gradation. If the porosity is too high (e.g., above 8%), the gaps between particles are too large, resulting in excessive resin filling these gaps, leading to numerous voids and low density after calcination. Conversely, if the porosity is too low (e.g., below 5%), the particles are too tightly bound, hindering resin flow and resulting in some voids remaining unfilled. Even if resin fills all voids, the amount is insufficient to bind the SiO2 particles together, preventing the formation of large blocks of silica. The SiO2 particles used as raw material can be of any shape (e.g., spherical or near-spherical), as long as the porosity meets the above requirements, quartz sand with fewer voids can be obtained. In the preparation method of the present invention, the mass ratio of SiO2 particles to resin should also be within a certain range. When the amount of resin is too large (for example, the mass ratio of SiO2 particles to resin is less than 10:1), the amount of resin is too large, which will result in low density of the obtained quartz sand; when the amount of resin is too small (for example, the mass ratio of SiO2 particles to resin is higher than 10:1), the resin is insufficient to bind the SiO2 particles together, resulting in the failure to obtain large blocks of silica.

[0016] In this patent, "porosity" is obtained by detecting it using the fluid filling method.

[0017] To avoid residual impurities in the resin after calcination, the resin used in this invention is preferably a thermosetting resin that does not contain metal elements, nitrogen, or sulfur. For example, the resin can be one or more of epoxy resin, phenolic resin, silicone resin, and polybutadiene resin.

[0018] The curing step is preferably carried out in a vacuum environment to avoid the introduction of impurities from the air, thereby improving the purity of the resulting quartz sand. Specific curing conditions can be curing at 80-150℃ for 6-8 hours. The appropriate curing temperature and time can be selected based on the type of resin used. For example, when the resin is epoxy resin, the curing temperature is 80-120℃ and the curing time can be 6-8 hours; when the resin is methacrylic resin, the curing temperature is 120-150℃ and the curing time can be 1-4 hours.

[0019] The calcination step first removes the resin, followed by calcination to sinter the SiO2 particles into large silica blocks. In the resin removal stage, the temperature can be initially raised to 500-800℃ and held at that temperature for a certain time to completely remove the resin. This stage can involve raising the temperature to 500-800℃ at a rate of 1-5℃ per minute, and holding it at that temperature for an appropriate time (e.g., 2 hours, 3 hours, etc.) to ensure complete resin removal. Subsequently, the calcination temperature can be increased to soften and liquefy the SiO2 particles, causing them to bind together to form large silica blocks. In this stage, the temperature can be raised to above 1000℃ (e.g., 1000℃, 1100℃, 1200℃, 1300℃, 1400℃, 1500℃, 1600℃, 1700℃, etc.) at a rate of 1-5℃ per minute, and then held at that temperature for 2-20 hours.

[0020] The method of this invention does not introduce other impurities, therefore high-purity quartz sand can be obtained using high-purity SiO2 particles. Preferably, the purity of the SiO2 particles used as raw materials is 99.9999% or higher to obtain high-purity quartz sand.

[0021] In the preparation method of the present invention, the SiO2 particles used as raw materials are preferably spherical and / or near-spherical with high fluidity and high filling capacity. The SiO2 particles can be crystalline or amorphous.

[0022] The present invention is further described below through specific examples. However, these examples are merely exemplary and do not constitute any limitation on the scope of protection of the present invention. Unless otherwise specified, the reagents, materials, and instruments used in the following embodiments and comparative examples are commercially available.

[0023] Example 1

[0024] SiO2 spheres with a particle size of 100nm-20μm were graded (purity 99.9999%) to achieve a porosity of 5%. Then, 1kg of the graded SiO2 spheres were mixed evenly with 63g of bisphenol A epoxy resin.

[0025] The mixture was heated to 120°C under vacuum drying and held for 8 hours to obtain bulk solids.

[0026] The solidified material was placed in a box furnace for calcination. The temperature was first increased to 800°C at a rate of 1°C per minute and held at 800°C for 2 hours to fully remove organic matter. Then, the temperature was increased to 1300°C at a rate of 2°C per minute and held for 10 hours. Large blocks of silica were obtained after calcination.

[0027] After the calcined silica blocks are naturally cooled to room temperature, they are crushed and sieved using a vibrating screen. Particles with a diameter of 50-300 μm are retained as high-purity silica sand. This silica sand has a purity of 99.9999%, few internal voids, and a density of 1.24 g / cm³. 3 .

[0028] Example 2

[0029] This example provides a method for synthesizing quartz sand, which is basically the same as in Example 1, except that the porosity after gradation is 8%, and the amount of bisphenol A epoxy resin used is 100g. Calcination yields synthetic quartz sand with a purity of 99.9999%, few voids, and a density of 1.24g / cm³. 3 .

[0030] Example 3

[0031] This example provides a method for synthesizing silica sand, which is basically the same as in Example 1, except that the porosity after gradation is 6% and the amount of bisphenol A epoxy resin used is 76g. Calcination yields synthetic silica sand with a purity of 99.9999%, few voids, and a density of 1.24g / cm³. 3 .

[0032] Example 4

[0033] This example provides a method for synthesizing silica sand, which is basically the same as in Example 1, except that the resin used is changed to phenolic resin. Calcination yields synthetic silica sand with a purity of 99.9999%, few voids, and a density of 1.24 g / cm³. 3 .

[0034] Comparative Example 1 This example provides a method for synthesizing silica sand, which is basically the same as in Example 1, except that the porosity after gradation is 10% and the amount of bisphenol A epoxy resin used is 125g. Finally, synthetic silica sand with a purity of 99.9999% is obtained, but the silica sand has a relatively large number of voids and a density of 1.23g / cm³. 3 .

[0035] Comparative Example 2 This example provides a method for synthesizing quartz sand, which is basically the same as in Example 1, except that the amount of bisphenol A epoxy resin used is 150g. Finally, synthetic quartz sand is obtained with a purity of 99.9999%, but the quartz sand has many voids and a density of 1.21g / cm³. 3 .

[0036] Comparative Example 3 This example provides a method for synthesizing silica sand, which is basically the same as in Example 1, except that the amount of bisphenol A epoxy resin used is 30g. After mixing the two, the mixture is heated and cured. Because the amount of resin is too small, it is impossible to effectively bind all the SiO2 particles together. Therefore, a silica sand product cannot be obtained.

[0037] Comparative Example 4 This example provides a method for synthesizing silica sand, which is basically the same as in Example 1, except that the SiO2 spheres are not graded; instead, only SiO2 spheres with a particle size of 20 μm are used, resulting in a porosity of 26% after stacking. 325 g of bisphenol A epoxy resin is used. Finally, synthetic silica sand with a purity of 99.9999% is obtained, but the silica sand has a relatively large number of voids and a density of 1.20 g / cm³. 3 .

[0038] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing quartz sand, characterized in that, include: SiO2 particles are mixed with resin to obtain a mixture; The mixture is heated and cured. The cured solid was calcined to remove the resin and obtain bulk silica. as well as The silica lumps are crushed to obtain quartz sand with a particle size distribution between 50-300μm; The particle size distribution of the SiO2 particles is 100nm-20μm, and the porosity of the SiO2 particles is 5%-8%; the mass ratio of the SiO2 particles to the resin is (10-16):

1.

2. The preparation method according to claim 1, characterized in that, The resin is a thermosetting resin that does not contain metal elements, nitrogen, or sulfur.

3. The preparation method according to claim 2, characterized in that, The resin is one or more of epoxy resin, phenolic resin, silicone resin, methacrylic resin and polybutadiene resin.

4. The preparation method according to claim 1, characterized in that, The curing process involves curing in a vacuum environment at a temperature of 80-150℃ for 6-8 hours.

5. The preparation method according to claim 4, characterized in that, When the resin is epoxy resin, the curing temperature is 80-120℃ and the curing time is 6-8 hours; When the resin is methacrylic resin, the curing temperature is 120-150℃ and the curing time is 1-4 hours.

6. The preparation method according to claim 1, characterized in that, The calcination process involves first heating the temperature to 500-800°C and holding it at that temperature for a certain period of time to remove the resin; then heating the temperature to above 1000°C and holding it at that temperature for 2-20 hours.

7. The preparation method according to claim 1, characterized in that, The purity of the SiO2 particles is above 99.9999%.

8. The preparation method according to any one of claims 1-7, characterized in that, The SiO2 particles are spherical and / or near-spherical.