Method for preparing high-purity quartz sand by using organosilane in cooperation with water glass

Abstract

This invention relates to the field of quartz sand preparation technology, and more particularly to a method for preparing high-purity quartz sand using organosilanes in conjunction with water glass. The method includes: reacting quartz sand raw material with a water glass solution to obtain a first mixture; subjecting the first mixture to a first washing treatment, followed by solid-liquid separation to obtain a dehydrated liquid and a wet quartz sand filter cake; determining whether the first washing treatment meets the standard based on the conductivity of the dehydrated liquid; in response to the first washing treatment meeting the standard, mixing the wet quartz sand filter cake with an acid solution to obtain a second mixture and stirring it; determining whether the dispersion state of the second mixture is qualified based on the dispersion coefficient; in response to the second mixture meeting the dispersion state, performing a second washing treatment followed by drying to obtain a dry quartz sand filter cake, and then performing sodium ion removal treatment to obtain a grafting coefficient to determine an organosilane solution spray treatment strategy to obtain the finished quartz sand. This invention improves the purity of quartz sand.

Description

Technical Field

[0001] This invention relates to the field of quartz sand preparation technology, and in particular to a method for preparing high-purity quartz sand using organosilanes in conjunction with water glass. Background Technology

[0002] High-purity silica sand is a key filler or reinforcement in electronic materials such as high-frequency copper-clad laminates and advanced semiconductor packaging. Its purity and interfacial properties directly determine the dielectric properties, mechanical strength, and long-term reliability of composite materials. On the one hand, the silica sand must have extremely low metallic impurity content; on the other hand, its surface must have excellent chemical compatibility and bonding force with the organic resin matrix. This is usually achieved by grafting organosilane coupling agents onto the surface.

[0003] Chinese Patent Publication No. CN117049555A discloses a method for preparing high-purity quartz sand, comprising the following steps: S1, adding fumed silica and ultrapure water to a beaker to obtain a silica gel precursor; S2, adding ultrapure water and acid to a container, uniformly mixing alcohol and organosilane, and adding the mixture of alcohol and organosilane to the container to obtain a silica sol; S3, mixing the silica gel precursor and silica sol to obtain a gel; S4, drying the gel to obtain a dried product; S5, grinding the dried product, sieving and classifying it, and calcining it to obtain high-purity quartz sand. This invention uses industrial fumed silica as a silica gel precursor and organosilane hydrolyzed under acidic conditions as a silica sol precursor. By replacing the organosilicon source with fumed silica, the amount of organosilane used is saved, and the waste of silicon source caused by incomplete hydrolysis of organosilane is avoided, thereby improving the product yield. The reaction conditions are mild, the process is simple, the amount of catalyst added is small, and it is safe and environmentally friendly.

[0004] Therefore, the aforementioned method for preparing high-purity quartz sand has the following problems:

[0005] 1. Lacking sufficient and uniform surface active sites necessary for chemical bonding with the organic resin matrix, it is impossible to achieve excellent interfacial bonding through grafting.

[0006] 2. Relying on high-cost industrial fumed silica and organosilanes as raw materials results in poor industrialization economics, and the ultimate purity limit of quartz sand products is limited by the purity of these chemical raw materials themselves. Summary of the Invention

[0007] Therefore, this invention provides a method for preparing high-purity quartz sand using organosilanes in conjunction with water glass, in order to overcome the problem that it is difficult to achieve the synergistic purification and controllable modification of quartz sand impurities in the prior art.

[0008] To achieve the above objectives, the present invention provides a method for preparing high-purity quartz sand using organosilanes in conjunction with water glass, comprising:

[0009] Quartz sand raw material with a preset solid-liquid ratio is mixed with water glass solution to carry out reaction treatment to obtain a first mixture. The first mixture is then subjected to a first washing treatment and a solid-liquid separation treatment to obtain a dehydrated liquid and a wet quartz sand filter cake. The conductivity of the dehydrated liquid is obtained to determine whether the first washing treatment meets the standard.

[0010] In response to the first washing treatment meeting the standard, the wet quartz sand filter cake is mixed with acid to obtain a second mixture, and a stirring treatment is performed. The viscosity and particle size of the second mixture within a preset temperature range during the stirring treatment are obtained to calculate the dispersion coefficient and determine whether the dispersion state of the second mixture is qualified.

[0011] In response to the qualified dispersion state of the second mixture, the second mixture is subjected to a second washing treatment and then dried to obtain a dry quartz sand filter cake, and then subjected to sodium ion removal treatment to obtain the sodium ion content and surface hydroxyl concentration in the dry quartz sand filter cake after sodium ion removal treatment.

[0012] The grafting coefficient is determined based on the surface hydroxyl concentration and the sodium ion content, and compared with a preset grafting coefficient to determine the organosilane solution spraying treatment strategy to obtain the finished quartz sand.

[0013] The preset solid-liquid ratio is a weight ratio of quartz sand raw material to water glass solution of 1:2 to 1:3, and the preset temperature range is 40℃ to 60℃.

[0014] Furthermore, based on the fact that the conductivity is less than a preset conductivity, the first washing process is determined to have met the standard, wherein,

[0015] The first washing process involves intermittent stirring, with 3 to 5 washing cycles. The mass ratio of ultrapure water to the first mixture is 2:1 to 3:1 for each washing cycle. The washing temperature is 25°C to 40°C, and the stirring time for each washing cycle is 10 to 15 minutes. After standing for 10 to 20 minutes to allow sedimentation, the supernatant is separated.

[0016] Furthermore, based on the dispersion coefficient being greater than or equal to a preset dispersion coefficient, the dispersion state of the second mixture is determined to be qualified, wherein,

[0017] The dispersion coefficient is the product of the ratio of the initial viscosity to the real-time viscosity of the second mixture and the ratio of the initial particle size to the real-time particle size of the second mixture.

[0018] Furthermore, based on the grafting coefficient being greater than or equal to a preset grafting coefficient, the organosilane solution spray treatment strategy is determined as the first treatment strategy, wherein...

[0019] The grafting coefficient is the product of the ratio of the measured surface hydroxyl concentration of the dry quartz sand filter cake to the reference hydroxyl concentration and the ratio of the measured sodium ion content of the dry quartz sand filter cake to the reference sodium ion content.

[0020] The first processing strategy involves placing the dry quartz sand filter cake in a fluidized bed spray coating machine, preheating it to 110℃~130℃, and spraying it with an organosilane solution at a spray rate of 0.5mL / min~1.0mL / min for 20~30 minutes. The sprayed quartz sand is then cured at a curing temperature of 150℃~180℃ for 60~90 minutes to obtain the finished quartz sand.

[0021] Furthermore, based on the fact that the grafting coefficient is less than a preset grafting coefficient, the organosilane solution spray treatment strategy is determined to be the second treatment strategy, wherein...

[0022] The second processing strategy involves placing the dry quartz sand filter cake in a fluidized bed spray coating machine, preheating it to 110℃~130℃, and spraying an organosilane solution at a spray rate of 0.5mL / min~1.0mL / min for 20~30 minutes. While maintaining the preheated temperature, a nitrogen atmosphere containing 0.5%~1.0% ammonia is introduced for 30~45 minutes. The quartz sand after the atmosphere is introduced is then cured at a curing temperature of 150℃~180℃ for 60~90 minutes to obtain the finished quartz sand.

[0023] Furthermore, the water glass solution is sodium water glass (Na2O·nSiO2) with a modulus of 3.0 to 3.4 and a concentration of 30% to 40% by mass fraction of silicon dioxide. Before use, it is filtered through a 0.45 μm filter membrane to remove impurities.

[0024] Further, the organosilane solution comprises the following components: 5%–10% alkoxysilane by mass, 85%–92% anhydrous ethanol, 2%–5% deionized water, and 0.5%–1.5% glacial acetic acid by mass of the alkoxysilane.

[0025] The alkoxysilane is one or more of methyltrimethoxysilane, vinyltriethoxysilane, and γ-aminopropyltriethoxysilane.

[0026] Furthermore, the acid solution is a mixture of hydrochloric acid with a mass fraction of 5% to 15% and hydrofluoric acid with a mass fraction of 1% to 5%, with a volume ratio of hydrochloric acid to hydrofluoric acid of 5:1 to 10:1, and a solid-liquid mass ratio of the wet quartz sand filter cake to the acid solution of 1:2 to 1:4.

[0027] Further, the reaction process involves mixing quartz sand raw material with ultrapure water at a solid-liquid ratio of 1:0.3 to 1:0.5, stirring at a speed of 100 rpm to 150 rpm for 5 to 10 minutes, preheating the water glass solution to 60°C to 70°C, increasing the stirring speed to 300 rpm to 400 rpm, and uniformly adding it to the quartz sand raw material over 10 to 15 minutes using a constant flow pump. After the water glass solution is added, the temperature is raised to 70°C to 80°C, maintaining a stirring speed of 300 rpm to 400 rpm for 90 minutes.

[0028] Further, the sodium ion removal process involves mixing the dried quartz sand filter cake with ammonium-type strong acid cation exchange resin at a mass ratio of 10:1 to 20:1, placing the mixture in a rotary reactor, and heating it from room temperature to 300°C to 400°C at a rate of 5°C / min under a nitrogen protective atmosphere. The temperature is maintained for 60 to 120 minutes, and the mixture is then naturally cooled to below 80°C. Finally, a vibrating screen is used to separate the quartz sand from the ion exchange resin.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention uses water glass solution to create a silicate active intermediate layer on the surface of the quartz sand raw material, avoiding excessive erosion of the silica matrix by acid. Furthermore, the reaction endpoint of the wet quartz sand filter cake mixed with acid is determined by the dispersion coefficient, avoiding problems such as impurity residue due to under-washing or excessive dissolution of the silica matrix and unstable hydroxyl generation due to over-washing, thus protecting the integrity of the quartz sand structure. The sodium ion removal treatment reduces the content of sodium ions, which affect dielectric properties, in the quartz sand, thereby achieving deep purification of the quartz sand. The determination of the hydroxyl concentration on the surface of the quartz sand after sodium removal enables quantitative diagnosis of the chemical activity of the quartz sand surface. Based on the grafting coefficient, it ensures that high-quality, uniform, and dense organosilane monolayer grafting can be adaptively completed even when there are differences in the surface chemical state of different batches of quartz sand, guaranteeing the excellent dielectric properties of the finished quartz sand in high-frequency electronic material applications.

[0030] Furthermore, this invention involves mixing quartz sand raw material with water glass for reaction treatment, thereby constructing a silicate active intermediate layer on the surface of the quartz sand raw material. The porous structure of the silicate active intermediate layer promotes the penetration and diffusion of acid, allowing the metal oxide impurities encased inside to be fully exposed. Moreover, the silicate active intermediate layer preferentially reacts with acid in the early stage of pickling, playing a sacrificial buffering role and delaying the direct erosion of the quartz sand silica matrix by hydrofluoric acid. This resolves the contradiction between deep impurity removal and matrix protection in the traditional pickling process.

[0031] Furthermore, this invention mixes quartz sand raw material with acid solution and stirs it, and obtains the viscosity and particle size of the second mixture during the stirring process to calculate the dispersion coefficient and determine the dispersion state of the second mixture. Based on the dispersion coefficient, the stirring process is determined, which avoids the problems of matrix damage and incomplete removal of metal oxide impurities caused by under-washing and over-washing, improves the purity of quartz sand products, and reduces the dissolution loss of quartz sand.

[0032] Furthermore, this invention removes sodium ions in the form of impurities from the surface and near-surface layer of quartz sand through sodium ion removal treatment, utilizing ion exchange reactions. This reduces the concentration of ionic defects on the quartz sand surface, eliminates the migration behavior of sodium ions under an electric field, improves the intrinsic dielectric purity of the quartz sand, reduces the risk of induced charge accumulation or partial discharge during high-temperature processing or use, and enhances the long-term electrical reliability of the finished quartz sand. In addition, the clean quartz sand surface provides a purer reaction interface for the chemical grafting of organosilicon molecules, avoiding the poisoning effect of sodium ions on the hydrolysis-condensation reaction of silanes, resulting in a more complete and robust Si-O-Si covalent network.

[0033] Furthermore, this invention determines the spray treatment strategy for organosilanes and dry quartz sand filter cake by using the grafting coefficient. This solves the problem of uneven chemical activity on the surface of quartz sand caused by process fluctuations, resulting in unstable organosilane grafting effects. Surface hydroxyl groups are active sites for the condensation reaction of silane molecules, and their concentration affects the rate of the grafting reaction. Sodium ion content can shield active sites and hinder the formation of silicon-oxygen bonds. The grafting coefficient can be used to assess the effective activity of the quartz sand surface, achieving matching of chemical conditions and precise guidance of the grafting reaction on the quartz sand surface, thereby ensuring the interfacial properties and batch stability of the finished quartz sand. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating the steps of a method for preparing high-purity quartz sand using organosilane and water glass, as described in an embodiment of the present invention.

[0035] Figure 2 This is a logic diagram illustrating how the washing process meets the standards in an embodiment of the present invention.

[0036] Figure 3 A logic diagram for determining whether the dispersion state of the second mixture is qualified in an embodiment of the present invention;

[0037] Figure 4 The diagram shows the logic for determining the spray treatment strategy of organosilane solution in an embodiment of the present invention. Detailed Implementation

[0038] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0039] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0040] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0041] Please see Figure 1 The diagram shown is a flowchart of the steps in the method for preparing high-purity quartz sand using organosilane and water glass in accordance with an embodiment of the present invention.

[0042] The method for preparing high-purity quartz sand using organosilane and water glass in accordance with this invention includes:

[0043] Step S1: Mix the quartz sand raw material with water glass solution at a preset solid-liquid ratio to obtain a first mixture. After the first mixture is washed, it is subjected to solid-liquid separation to obtain a dehydrated liquid and a wet quartz sand filter cake. The conductivity of the dehydrated liquid is obtained to determine whether the first washing treatment meets the standard.

[0044] Step S2: In response to the first washing treatment meeting the standard, the wet quartz sand filter cake is mixed with acid to obtain a second mixture, and a stirring treatment is performed. The viscosity and particle size of the second mixture in the preset temperature range during the stirring treatment are obtained to calculate the dispersion coefficient, and it is determined whether the dispersion state of the second mixture is qualified.

[0045] Step S3: In response to the qualified dispersion state of the second mixture, the second mixture is subjected to a second washing treatment and then dried to obtain a dry quartz sand filter cake and subjected to sodium ion removal treatment to obtain the sodium ion content and surface hydroxyl concentration in the dry quartz sand filter cake after sodium ion removal treatment.

[0046] Step S4: Determine the grafting coefficient based on the surface hydroxyl concentration and the sodium ion content, and compare it with the preset grafting coefficient to determine the organosilane solution spray treatment strategy to obtain finished quartz sand. The preset solid-liquid ratio is the weight ratio of quartz sand raw material to water glass solution, set to 1:2 to 1:3, and the preset temperature range is 40℃ to 60℃.

[0047] In this embodiment of the invention, the quartz sand raw material is natural quartz sand, the main component of which is silicon dioxide with a content of ≥99.5% and an initial particle size of 100μm~200μm.

[0048] Specifically, this invention uses a water glass solution to create a silicate active intermediate layer on the surface of the quartz sand raw material, preventing excessive erosion of the silica matrix by the acid solution. The reaction endpoint of the wet quartz sand filter cake mixed with the acid solution is determined by the dispersion coefficient, avoiding problems such as impurity residue due to under-washing or excessive dissolution of the silica matrix and unstable hydroxyl generation due to over-washing, thus protecting the integrity of the quartz sand structure. Furthermore, the sodium ion removal treatment reduces the content of sodium ions, which affect the dielectric properties of the quartz sand, thereby achieving deep purification of the quartz sand. The determination of the hydroxyl concentration on the surface of the quartz sand after sodium removal enables a quantitative diagnosis of the chemical activity of the quartz sand surface. Based on the grafting coefficient, it ensures that high-quality, uniform, and dense organosilane monolayer grafting can be adaptively completed even when there are differences in the surface chemical state of different batches of quartz sand, guaranteeing the excellent dielectric properties of the finished quartz sand in high-frequency electronic material applications.

[0049] Please see Figure 2 As shown, it is a logic judgment diagram for determining whether the first washing process meets the standard in an embodiment of the present invention.

[0050] Specifically, a quartz sand raw material with a preset solid-liquid ratio is mixed with a water glass solution to undergo a reaction treatment to obtain a first mixture. The first mixture is then subjected to a first washing treatment followed by a solid-liquid separation treatment to obtain a dehydrated liquid and a wet quartz sand filter cake. The conductivity of the dehydrated liquid is obtained to determine whether the first washing treatment meets the standard.

[0051] If the conductivity is greater than or equal to the preset conductivity, then the first washing process is determined to be substandard.

[0052] If the conductivity is less than the preset conductivity, then the first washing process is deemed to have met the standard.

[0053] In this embodiment of the invention, the conductivity is obtained by using an online conductivity meter with temperature compensation and an electrode constant of 1.0 to measure and record the dehydrated liquid in real time.

[0054] In this embodiment of the invention, the preset solid-liquid ratio represents the weight ratio of quartz sand raw material to water glass solution. The value range is determined to be 1:2 to 1:5 based on process conditions and experimental verification, preferably 1:3. This ensures that the surface of the quartz sand is fully wetted and coated by water glass, while avoiding uneven stirring due to excessive viscosity or reduced reaction efficiency due to excessive thinness. However, the above value is not limited to this, and those skilled in the art can adjust the value according to actual needs.

[0055] In this embodiment of the invention, the preset conductivity is determined to be ≤10μS / cm based on process conditions and experimental verification, preferably ≤5μS / cm. However, the above value is not limited to this, and those skilled in the art can adjust the value according to actual needs.

[0056] In this embodiment of the invention, the reaction process is as follows: quartz sand raw material and ultrapure water are mixed at a solid-liquid ratio of 1:0.3 to 1:0.5, with a stirring speed of 100 rpm to 150 rpm and a stirring time of 5 to 10 minutes. The water glass solution is preheated to 60°C to 70°C, and the stirring speed is increased to 300 rpm to 400 rpm. The water glass solution is then added to the quartz sand raw material at a constant flow pump over 10 to 15 minutes. After the water glass solution is added, the temperature is raised to 70°C to 80°C, and the stirring speed is maintained at 300 rpm to 400 rpm for 90 minutes.

[0057] In this embodiment of the invention, the first washing process is carried out by intermittent stirring, with 3 to 5 washing cycles. The mass ratio of ultrapure water to the first mixture is 2:1 to 3:1 for each washing cycle. The washing temperature is 25°C to 40°C, and the stirring time for each washing cycle is 10 to 15 minutes. After standing for 10 to 20 minutes to settle, the supernatant is separated.

[0058] In this embodiment of the invention, the ultrapure water is ultrapure water with a resistivity ≥18.2MΩ·cm at 25℃, and the water glass solution is sodium water glass (Na2O·nSiO2) with a modulus of 3.0 to 3.4 and a concentration of 30% to 40% by mass fraction of silicon dioxide. Before use, it is filtered through a 0.45μm filter membrane to remove impurities.

[0059] In this embodiment of the invention, the solid-liquid separation process is carried out by using a plate and frame filter press, controlling the filtration pressure to be 0.4-0.6 MPa, the separation time to be 10-20 minutes, and the process ends when no obvious liquid droplets flow out continuously from the filter plate outlet, to obtain wet quartz sand filter cake and dewatered liquid.

[0060] Specifically, in response to the failure of the first washing treatment to meet the standard, it is determined that the wet quartz sand filter cake will be washed with ultrapure water until the first washing treatment meets the standard.

[0061] Specifically, the water glass solution itself is alkaline, which has a significant activating and modifying effect on the surface of the quartz sand raw material. In the alkaline medium provided by the water glass solution, the silicate ions can undergo a condensation reaction with the silanol groups on the surface of the quartz sand to form a strong -Si-O-Si- bond, thereby constructing a uniform and porous silicate active coating layer on the surface of the quartz sand. The silicate active coating layer can not only fill the surface micro-defects, but also act as a reaction intermediate to change the interfacial properties of acid washing. The porous and amorphous structure of the silicate active coating layer improves the wettability and permeability of the quartz sand surface to acid, allowing the metal oxide impurities encased inside to be fully exposed. In the early stage of acid washing, the silicate active coating layer can preferentially react with acid, temporarily buffering the direct and severe erosion of the silica matrix by hydrofluoric acid, thus creating a wider and more controllable reaction window for the selective and gradual dissolution of metal impurities in terms of kinetics.

[0062] Specifically, this invention involves mixing quartz sand raw material with water glass for reaction treatment, thereby constructing a silicate active intermediate layer on the surface of the quartz sand raw material. The porous structure of the silicate active intermediate layer promotes the penetration and diffusion of acid, allowing the metal oxide impurities encased inside to be fully exposed. Furthermore, the silicate active intermediate layer preferentially reacts with acid in the early stages of pickling, acting as a sacrificial buffer and delaying the direct erosion of the quartz sand silica matrix by hydrofluoric acid. This resolves the contradiction between deep impurity removal and matrix protection in traditional pickling processes.

[0063] Please see Figure 3 As shown, it is a logic judgment diagram for determining whether the dispersion state of the second mixture is qualified according to an embodiment of the present invention.

[0064] Specifically, in response to the first washing treatment meeting the standard, the wet quartz sand filter cake is mixed with acid to obtain a second mixture, and a stirring treatment is performed. The viscosity and particle size of the second mixture within a preset temperature range during the stirring treatment are obtained to calculate the dispersion coefficient and determine whether the dispersion state of the second mixture is qualified.

[0065] If the dispersion coefficient is greater than or equal to the preset dispersion coefficient, the dispersion state of the second mixture is determined to be qualified.

[0066] If the dispersion coefficient is less than the preset dispersion coefficient, the dispersion state of the second mixture is determined to be unqualified.

[0067] In this embodiment of the invention, the dispersion coefficient is the product of the ratio of the initial viscosity to the real-time viscosity of the second mixture and the ratio of the initial particle size to the real-time particle size of the second mixture. The determination of the initial viscosity and the initial particle size is prior art and will not be described in detail here.

[0068] In this embodiment of the invention, based on the fact that the removal efficiency of iron and aluminum impurities in the quartz sand raw material is greater than 95% in several historical stirring processes, the range of the preset dispersion coefficient is determined to be [1.5, 2.0], preferably set to 1.75. However, the above value is not limited to this, and those skilled in the art can also adjust the value according to actual needs.

[0069] In this embodiment of the invention, the preset temperature range is [40℃, 60℃], preferably set to 50℃, but the above value is not limited to this, and those skilled in the art can adjust the value according to actual needs.

[0070] In this embodiment of the invention, the acid solution is one or more of hydrochloric acid, nitric acid, sulfuric acid, and hydrofluoric acid, preferably a mixture of hydrochloric acid with a mass fraction of 5% to 15% and hydrofluoric acid with a mass fraction of 1% to 5%, wherein the volume ratio of hydrochloric acid to hydrofluoric acid is 5:1 to 10:1, and the solid-liquid mass ratio of the wet quartz sand filter cake to the acid solution is 1:2 to 1:4, used to dissolve metal oxide impurities on the surface of the quartz sand raw material.

[0071] In this embodiment of the invention, the stirring process is carried out within a preset temperature range, with a stirring speed of 200 rpm to 500 rpm. The initial viscosity and initial particle size of the second mixture are recorded within the second to fifth minutes after the stirring begins, and then the viscosity and particle size data are collected in real time at a frequency of once per minute.

[0072] Specifically, in response to the unqualified dispersion state of the second mixture, the mixing time is increased by a stirring coefficient of 1.5.

[0073] In this embodiment of the invention, the range of the reference stirring time is [15 min, 45 min], preferably 30 min; the range of the maximum stirring time is [60 min, 120 min], preferably 90 min; and the range of the stirring coefficient is [1.1, 2.0], preferably 1.5. However, the above values ​​are not limited to these, and those skilled in the art can adjust the values ​​according to actual needs.

[0074] In this embodiment of the invention, the increased stirring time is the product of the base stirring time and the stirring coefficient.

[0075] In this embodiment of the invention, the judgment logic for whether the dispersion state is qualified is as follows: if the real-time dispersion coefficient is greater than or equal to the preset dispersion coefficient within the reference stirring time, it is determined to be qualified and stirring is stopped; if the reference stirring time is still lower than the preset dispersion coefficient, it is determined to be unqualified and the stirring time adjustment program is started.

[0076] In this embodiment of the invention, the stirring time adjustment procedure is as follows: multiply the baseline stirring time by the stirring coefficient to obtain the increased stirring time, continue to monitor and compare the dispersion coefficient until the standard is met or the maximum stirring time is reached; if the dispersion coefficient still does not meet the standard after reaching the maximum stirring time, the second mixture is determined to be unqualified and discarded.

[0077] Specifically, during the mixing and stirring of quartz sand raw materials with acid, the metal oxide impurities on the surface of the quartz sand are dissolved by the acid. This process simultaneously triggers two physical effects: first, the dissolution of the impurity layer and the opening of particle agglomerates lead to a continuous reduction in the average particle size of the quartz sand particles; second, a large number of metal ions dissolve into the acid, changing the rheological properties of the mixture, which manifests as a change in viscosity.

[0078] Specifically, in traditional processes, insufficient reaction time between quartz sand raw materials and acid leads to inadequate removal of metal oxide impurities, while excessive reaction time causes the acid to erode the silica matrix of the quartz sand itself. Furthermore, excessive dissolution of silicon ions can generate unstable silanol groups, posing risks of bubbles and crystallization to quartz sand in high-temperature applications.

[0079] Specifically, this invention mixes quartz sand raw material with acid solution and stirs it, and obtains the viscosity and particle size of the second mixture during the stirring process to calculate the dispersion coefficient and determine the dispersion state of the second mixture. Based on the dispersion coefficient, the stirring process is determined, which avoids the problems of matrix damage and incomplete removal of metal oxide impurities caused by under-washing and over-washing, improves the purity of quartz sand products, and reduces the dissolution loss of quartz sand.

[0080] Specifically, the second washing process is carried out by intermittent stirring, with 3 to 5 washing cycles. The mass ratio of ultrapure water to the second mixture is 2:1 to 3:1 for each washing cycle. The washing temperature is 25℃ to 40℃, and the stirring time for each washing cycle is 10 to 15 minutes. After standing for 10 to 20 minutes to settle, the supernatant is separated. The washing endpoint is determined by detecting the pH value or conductivity of the washing solution. Preferably, the pH value of the washing solution is 5.0 to 7.0, and the conductivity is ≤10μS / cm.

[0081] Specifically, the drying process involves evenly spreading the wet quartz sand filter cake after the second washing treatment in an acid and alkali resistant tray, placing it in an electric heating drying oven, drying at a temperature of 105℃~120℃, drying for 2~4 hours, and obtaining a dry quartz sand filter cake with a material moisture content of ≤1.0%.

[0082] Specifically, the sodium ion removal treatment involves mixing dried quartz sand filter cake with ion exchanger at a mass ratio of 10:1 to 20:1, placing the mixture in a rotary reactor, and heating it from room temperature to 300°C to 400°C at a rate of 5°C / min under a nitrogen protective atmosphere for 60 to 120 minutes. This allows sodium ions on the surface and near-surface layer of the quartz sand to undergo a displacement reaction with hydrogen or ammonium ions in the exchanger. After treatment, the mixture is naturally cooled to below 80°C, and the quartz sand is separated from the ion exchanger using a vibrating screen.

[0083] In this embodiment of the invention, the ion exchanger is an ammonium type (NH4) + (Type) Strong acid cation exchange resin with an exchange capacity ≥4.8mmol / g and a particle size range of 0.4mm~0.8mm. It needs to be dried to constant weight at 105℃~120℃ before use.

[0084] In this embodiment of the invention, the active group of the ammonium-type cation exchange resin is ammonium sulfonate. Under heating conditions of 300℃ to 400℃, the ammonium ions decompose and release protons H. + It can replace sodium ions, and the generated ammonia gas (NH3) can be carried out by nitrogen protective gas.

[0085] In this embodiment of the invention, the process of obtaining sodium ion content is as follows: 10g of sample is randomly taken from the quartz sand after sodium ion removal treatment, a test solution is prepared by hydrofluoric acid-sulfuric acid digestion method, and the sodium ion concentration is determined by atomic absorption spectrometry or inductively coupled plasma atomic emission spectrometry. The result is expressed as the mass percentage of Na2O, and the detection limit is 0.001%.

[0086] In this embodiment of the invention, the process of obtaining the surface hydroxyl concentration is as follows: A 1g sample is randomly taken from the quartz sand after sodium ion removal treatment, ground to a particle size ≤2μm, and then mixed with dry potassium bromide at a mass ratio of 1:100 and pressed into tablets. The tablets are then heated at 4000–3000 cm⁻¹. -1 Scanning within the wavenumber range, at 3750 cm⁻¹ -1 The surface hydroxyl concentration was calculated by the area of ​​the characteristic absorption peak of free silanol groups. For higher concentrations, the internal standard method was used for quantification. The results were expressed as the number of hydroxyl moles per unit surface area (μmol / m²). 2 express.

[0087] Specifically, this invention removes sodium ions in the form of impurities from the surface and near-surface layer of quartz sand through sodium ion removal treatment. This reduces the concentration of ionic defects on the quartz sand surface, eliminates the migration behavior of sodium ions under an electric field, improves the intrinsic dielectric purity of the quartz sand, reduces the risk of induced charge accumulation or partial discharge during high-temperature processing or use, and enhances the long-term electrical reliability of the finished quartz sand. Furthermore, the clean quartz sand surface provides a purer reaction interface for the chemical grafting of organosilicon molecules, avoiding the poisoning effect of sodium ions on the hydrolysis-condensation reaction of silanes, resulting in a more complete and robust Si-O-Si covalent network.

[0088] Please see Figure 4 As shown, it is a logic diagram for determining the spray treatment strategy of organosilane solution in an embodiment of the present invention.

[0089] Specifically, the grafting coefficient is determined based on the surface hydroxyl concentration and the sodium ion content, and compared with the preset grafting coefficient to determine the organosilane solution spray treatment strategy to obtain finished quartz sand.

[0090] If the grafting coefficient is greater than or equal to the preset grafting coefficient, then the organosilane solution spray treatment strategy is determined to be the first treatment strategy.

[0091] If the grafting coefficient is less than the preset grafting coefficient, then the organosilane solution spray treatment strategy is determined to be the second treatment strategy.

[0092] In this embodiment of the invention, the grafting coefficient is the product of the ratio of the measured surface hydroxyl concentration of the dry quartz sand filter cake to the reference hydroxyl concentration and the ratio of the measured sodium ion content of the dry quartz sand filter cake to the reference sodium ion content.

[0093] In this embodiment of the invention, based on historical experiments, the range of the baseline hydroxyl concentration is [2.0 μmol / m]. 2 3.0 μmol / m 2 The preferred setting is 2.5 μmol / m 2 The reference sodium ion content ranges from [0.0005%, 0.0015%], preferably 0.001%, and the preset grafting coefficient ranges from [0.9, 1.1], preferably 1.0. However, the above values ​​are not limited to these values, and those skilled in the art can adjust the values ​​according to actual needs.

[0094] In this embodiment of the invention, the first processing strategy is to place the dry quartz sand filter cake in a fluidized bed spray coating machine, preheat the temperature to 110℃~130℃, spray an organosilane solution at a spray rate of 0.5mL / min~1.0mL / min for 20~30 minutes, and then cure the sprayed quartz sand at a curing temperature of 150℃~180℃ for 60~90 minutes to obtain the finished quartz sand.

[0095] In this embodiment of the invention, the second processing strategy is as follows: dry quartz sand filter cake is placed in a fluidized bed spray coating machine, preheated to 110℃~130℃, and an organosilane solution is sprayed at a spray rate of 0.5mL / min~1.0mL / min for 20~30 minutes. The preheating temperature is maintained, and a nitrogen atmosphere containing 0.5%~1.0% ammonia is introduced for 30~45 minutes. The quartz sand after the atmosphere is introduced is cured at a curing temperature of 150℃~180℃ for 60~90 minutes to obtain the finished quartz sand.

[0096] In this embodiment of the invention, the organosilane solution comprises the following components: 5%–10% alkoxysilane, 85%–92% anhydrous ethanol, 2%–5% deionized water, and 0.5%–1.5% glacial acetic acid, wherein the alkoxysilane is one or more of methyltrimethoxysilane, vinyltriethoxysilane, and γ-aminopropyltriethoxysilane.

[0097] Specifically, silane molecules hydrolyze to generate silanols, which undergo dehydration condensation with the silanols on the surface of quartz sand to form strong Si-O-Si covalent bonds, aligning the organic groups outwards. By obtaining the sodium ion content and surface hydroxyl concentration, the interference of sodium ions and the number of reaction sites in the dry quartz sand filter cake are determined. The first treatment strategy is adopted for dry quartz sand filter cakes with sufficient active sites and little sodium ion interference, aiming to efficiently complete the grafting and form a monomolecular organosilane layer on the surface of the quartz sand.

[0098] Specifically, when the second treatment strategy is adopted, it indicates that the surface of the quartz sand is not ideal, indicating insufficient active sites or strong interference from sodium ions. Ammonia gas is introduced to catalyze the creation of an alkaline environment, which accelerates the secondary hydrolysis of silanes and catalyzes the condensation reaction, thereby overcoming the reaction barrier and achieving full grafting.

[0099] Specifically, this invention determines the spray treatment strategy for organosilanes and dry quartz sand filter cake by using a grafting coefficient. This solves the problem of uneven chemical activity on the surface of quartz sand caused by process fluctuations, resulting in unstable organosilane grafting effects. Furthermore, the surface hydroxyl groups are active sites for the condensation reaction of silane molecules, and their concentration affects the rate of the grafting reaction. Sodium ion content can shield active sites and hinder the formation of silicon-oxygen bonds. The effective activity of the quartz sand surface can be evaluated by using the grafting coefficient, achieving matching of chemical conditions and precise guidance of the grafting reaction on the quartz sand surface, thereby ensuring the interfacial properties and batch stability of the finished quartz sand.

[0100] In this embodiment of the invention, the raw materials and conditions used in Example 1 for preparing high-purity quartz sand are as follows: 1000g of quartz sand with SiO2 content ≥99.5% and particle size of 100-200 mesh; a sodium silicate solution with modulus of 3.2 and SiO2 mass fraction of 35%; an acid solution prepared by mixing 10% hydrochloric acid and 2% hydrofluoric acid at a volume ratio of 8:1; a preset conductivity of 5μS / cm and a preset dispersion coefficient of 1.75 used in washing and dispersion monitoring; an ammonium-type strong acid cation exchange resin with a mass ratio of 1:15 to quartz sand used in sodium ion removal treatment; a preset grafting coefficient of 1.0; and an organosilane solution composed of 8% γ-aminopropyltriethoxysilane, 90% anhydrous ethanol, 1.5% deionized water, and 0.5% glacial acetic acid by mass of silane.

[0101] Example 1: Weigh 1000g of quartz sand raw material and mix it with 300g of ultrapure water. Stir at 120rpm for 8 minutes. Preheat sodium silicate solution with a modulus of 3.2 and a SiO2 mass fraction of 35% to 65°C. Add the solution at a uniform speed over 12 minutes and increase the stirring speed to 350rpm. After the addition is complete, raise the temperature to 75°C and continue the reaction for 90 minutes to obtain the first mixture.

[0102] The first mixture was subjected to a first washing treatment. 2500g of ultrapure water was added each time, and the mixture was stirred at 30℃ and 200rpm for 12 minutes. After standing for 15 minutes, the supernatant was separated. This process was repeated 4 times. After solid-liquid separation, a wet quartz sand filter cake was obtained. The conductivity of the dehydrated liquid was measured to be 3.8μS / cm, confirming that the first washing treatment met the standard.

[0103] The wet quartz sand filter cake and acid solution were mixed at a solid-liquid ratio of 1:3 and stirred at 50℃ and 300 rpm. The initial viscosity was measured to be 15.2 mPa·s and the particle size D50 was 158 μm at the 3rd minute. The real-time viscosity was measured to be 8.1 mPa·s and the particle size D50 was 142 μm at the 28th minute. The dispersion coefficient was calculated to be 2.09, which is greater than the preset value of 1.75. The dispersion state was determined to be qualified, and stirring was stopped.

[0104] The second mixture was subjected to a second washing treatment, with 2500g of ultrapure water added each time. The mixture was stirred at 30℃ and 200rpm for 12 minutes, and then separated after standing for 15 minutes. This process was repeated 3 times. The final filtrate conductivity was 4.5μS / cm and the pH was 6.2. After solid-liquid separation, the wet filter cake was dried at 110℃ for 3 hours to obtain dry quartz sand filter cake.

[0105] The dry filter cake was mixed with ammonium-type strong acid cation exchange resin at a mass ratio of 15:1. Under nitrogen protection, the mixture was heated to 350℃ at a rate of 5℃ / min, held at this temperature for 90 minutes, and then cooled to obtain desodium-removed silica sand. The sodium ion content was measured to be 0.0009%, and the surface hydroxyl concentration was 2.7 μmol / m³. 2 The grafting coefficient was calculated to be 1.20, and the first treatment strategy was determined.

[0106] The sodium-removed quartz sand was preheated to 120°C, sprayed with organosilane solution at a rate of 0.8 mL / min for 25 minutes, and then cured at 165°C for 75 minutes to obtain the finished quartz sand.

[0107] In this embodiment of the invention, the raw materials and conditions used in Example 2 for preparing high-purity quartz sand are as follows: 1000g of quartz sand with SiO2 content ≥99.5% and particle size of 100-200 mesh; a sodium silicate solution with modulus of 3.4 and SiO2 mass fraction of 35%; an acid solution prepared by mixing 12% hydrochloric acid and 2.5% hydrofluoric acid at a volume ratio of 10:1; a preset conductivity of 5μS / cm; a preset dispersion coefficient of 1.75; an ammonium-type strong acidic cation exchange resin used for sodium ion removal treatment with a mass ratio of 1:15 to quartz sand; a preset grafting coefficient of 1.0; and an organosilane solution composed of 8% γ-aminopropyltriethoxysilane, 90% anhydrous ethanol, 1.5% deionized water, and 0.5% glacial acetic acid by mass of silane.

[0108] Example 2: Weigh 1000g of quartz sand raw material and mix it with 300g of ultrapure water. Stir at 120rpm for 8 minutes. Preheat a sodium silicate solution with a modulus of 3.4 and a SiO2 mass fraction of 35% to 65°C. Add the solution at a uniform speed over 12 minutes and increase the stirring speed to 350rpm. After the addition is complete, raise the temperature to 75°C and continue the reaction for 90 minutes to obtain the first mixture.

[0109] The first mixture was subjected to a first washing treatment. 2500g of ultrapure water was added each time, and the mixture was stirred at 30℃ and 200rpm for 12 minutes. After standing for 15 minutes, the supernatant was separated. This process was repeated 4 times. After solid-liquid separation, a wet quartz sand filter cake was obtained. The conductivity of the dehydrated liquid was measured to be 3.5μS / cm, confirming that the first washing treatment met the standard.

[0110] The wet quartz sand filter cake was mixed with acid solution (12% hydrochloric acid and 2.5% hydrofluoric acid in a volume ratio of 10:1) at a solid-liquid ratio of 1:3. The mixture was stirred at 50℃ and 300 rpm. The initial viscosity was measured to be 14.8 mPa·s and the particle size D50 was 156 μm at the 3rd minute. The real-time viscosity was measured to be 7.9 mPa·s and the particle size D50 was 140 μm at the 25th minute. The dispersion coefficient was calculated to be 2.15, which is greater than the preset value of 1.75. The dispersion state was determined to be qualified, and stirring was stopped.

[0111] The second mixture was subjected to a second washing treatment under the same conditions as in Example 1, with an endpoint filtrate conductivity of 4.2 μS / cm and pH of 6.3, yielding a dry quartz sand filter cake.

[0112] The dry filter cake was mixed with ammonium-type strong acid cation exchange resin at a mass ratio of 15:1. Under nitrogen protection, the mixture was heated to 380℃ at a rate of 5℃ / min, held at that temperature for 100 minutes, and then cooled to obtain desodiumed quartz sand. The sodium ion content was measured to be 0.0006%, the surface hydroxyl concentration was 2.9 μmol / m², and the grafting coefficient was calculated to be 1.93, thus determining the first treatment strategy.

[0113] The sodium-removed quartz sand was preheated to 120°C, sprayed with organosilane solution at a rate of 0.8 mL / min for 25 minutes, and then cured at 165°C for 75 minutes to obtain the finished quartz sand.

[0114] In this embodiment of the invention, the raw materials and conditions used to prepare high-purity quartz sand in Comparative Example 1 are as follows: 1000g of quartz sand raw material with SiO2 content ≥99.5% and particle size of 100-200 mesh; Comparative Example 1 does not undergo water glass treatment; the acid solution is prepared by mixing 10% hydrochloric acid and 2% hydrofluoric acid by volume ratio of 8:1; the preset conductivity is 5μS / cm, and the preset dispersion coefficient is 1.75; the mass ratio of ammonium-type strong acid cation exchange resin to quartz sand used for sodium ion removal treatment is 1:15; the preset grafting coefficient is 1.0; the organosilane solution consists of 8% γ-aminopropyltriethoxysilane, 90% anhydrous ethanol, 1.5% deionized water, and 0.5% glacial acetic acid by mass of silane.

[0115] Comparative Example 1

[0116] Comparative Example 1 aims to verify the effect of omitting the water glass treatment step.

[0117] The mixing conditions for the quartz sand raw material and the acid solution were the same as in Example 1, with stirring at 50°C and 300 rpm. At the 3rd minute, the initial viscosity was measured to be 16.1 mPa·s and the particle size D50 was 160 μm. Stirring continued until the 18th minute, at which point the real-time viscosity was 9.8 mPa·s and the particle size D50 was 148 μm. The calculated dispersion coefficient was 1.79, confirming the dispersion was acceptable, and stirring was stopped.

[0118] The conditions for the second washing treatment, drying treatment, sodium ion removal treatment, and organosilane spray treatment were all consistent with those in Example 1. The sodium ion content of the desodiumed quartz sand was measured to be 0.0022%, the surface hydroxyl concentration was 1.9 μmol / m², and the grafting coefficient was calculated to be 0.82. The second treatment strategy was determined to carry out organosilane solution spray treatment.

[0119] The sodium-removed quartz sand was preheated to 120°C and sprayed with an organosilane solution (composition as in Example 1) at a spray rate of 0.8 mL / min for 25 minutes. The preheated temperature was maintained, and a nitrogen atmosphere containing 0.8% ammonia was introduced into the system for 35 minutes. The quartz sand was then cured at a curing temperature of 165°C for 75 minutes to obtain the comparative finished quartz sand.

[0120] In this embodiment of the invention, the raw materials and conditions used in Comparative Example 2 for preparing high-purity quartz sand are as follows: 1000g of quartz sand raw material with SiO2 content ≥99.5% and particle size of 100-200 mesh; a sodium silicate solution with modulus of 3.2 and SiO2 mass fraction of 35% was used; the acid solution was prepared by mixing 10% hydrochloric acid and 2% hydrofluoric acid at a volume ratio of 8:1; the preset conductivity was 5μS / cm; the stirring time was fixed at 60 minutes; the mass ratio of ammonium-type strong acidic cation exchange resin to quartz sand used for sodium ion removal treatment was 1:15; the preset grafting coefficient was 1.0; the organosilane solution consisted of 8% γ-aminopropyltriethoxysilane, 90% anhydrous ethanol, 1.5% deionized water, and 0.5% glacial acetic acid.

[0121] Comparative Example 2

[0122] The aim is to verify the effect of fixed pickling time and neglecting the influence of dispersion coefficient.

[0123] Weigh 1000g of quartz sand raw material and mix it with 300g of ultrapure water. Stir at 120rpm for 8 minutes. Preheat a sodium silicate solution with a modulus of 3.2 and a SiO2 mass fraction of 35% to 65°C. Add the solution at a uniform speed over 12 minutes and increase the stirring speed to 350rpm. After the addition is complete, raise the temperature to 75°C and continue the reaction for 90 minutes to obtain the first mixture.

[0124] The first mixture was subjected to the same first washing treatment as in Example 1. After solid-liquid separation, a wet quartz sand filter cake was obtained. The conductivity of the dehydrated liquid was measured to be 3.9 μS / cm, confirming that the first washing treatment met the standard.

[0125] The conditions for reacting the wet quartz sand filter cake with the acid solution were kept consistent with those in Example 1 to obtain a second mixture. The second mixture was then stirred at 50°C and 300 rpm for a fixed time of 60 minutes. After stirring, the viscosity of the mixture was measured to be 6.5 mPa·s, and the particle size D50 was 135 μm.

[0126] The conditions for the second washing treatment of the acid-washed material were the same as in Example 1. The final filtrate conductivity was 5.1 μS / cm and the pH value was 6.0. After solid-liquid separation, the resulting wet filter cake was dried at 110°C for 3 hours to obtain dry quartz sand filter cake.

[0127] Dry silica sand filter cake was mixed with ammonium-type strong acid cation exchange resin at a mass ratio of 15:1. Under a nitrogen protective atmosphere, the temperature was increased from room temperature to 350℃ at a rate of 5℃ / min and held for 90 minutes to remove sodium ions. After treatment, the mixture was naturally cooled and separated to obtain sodium-removed silica sand. The sodium ion content was measured to be 0.0007%, the surface hydroxyl concentration was 3.8 μmol / m², and the grafting coefficient was calculated to be 2.17. The first treatment strategy was then determined.

[0128] The sodium-removed quartz sand was preheated to 120°C, sprayed with organosilane solution at a rate of 0.8 mL / min for 25 minutes, and then cured at 165°C for 75 minutes to obtain the finished quartz sand.

[0129] Table 1. Performance Test Results of Finished Quartz Sand

[0130]

[0131] In the embodiments of this invention, Examples 1 and 2 construct a sacrificial protective layer through water glass pretreatment, enabling pickling to deeply remove metallic impurities while protecting the integrity of the matrix. Pickling is terminated by the dispersion coefficient, avoiding matrix damage and unstable hydroxyl generation caused by over-washing. High-temperature sodium removal with ammonium resin reduces the content of sodium ions, a key impurity affecting dielectric properties, to an extremely low level. Example 1 obtained SiO2 purity higher than 99.998%, sodium ion content lower than 0.001%, and dielectric loss lower than 0.00012, meeting the intrinsic purity and electrical performance requirements of high-frequency electronic materials for quartz sand fillers.

[0132] In this embodiment of the invention, the results of Comparative Example 1 and Comparative Example 2 verify the effect of each step from the opposite perspective. Due to the lack of the water glass step, Comparative Example 1 resulted in incomplete removal of impurities, severe damage to the matrix, and significant deterioration of product purity and dielectric properties. Comparative Example 2, due to the lack of dispersion coefficient monitoring and the fixed long-term acid washing, although further reducing the sodium content, caused over-etching of the silica matrix, manifested as increased loss on ignition and increased dielectric loss.

[0133] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method of producing high purity quartz sand from organosilane in conjunction with water glass, characterized by, include: Quartz sand raw material with a preset solid-liquid ratio is mixed with water glass solution to carry out reaction treatment to obtain a first mixture. The first mixture is then subjected to a first washing treatment and a solid-liquid separation treatment to obtain a dehydrated liquid and a wet quartz sand filter cake. The conductivity of the dehydrated liquid is obtained to determine whether the first washing treatment meets the standard. In response to the first washing treatment meeting the standard, the wet quartz sand filter cake is mixed with acid to obtain a second mixture, and a stirring treatment is performed. The viscosity and particle size of the second mixture within a preset temperature range during the stirring treatment are obtained to calculate the dispersion coefficient and determine whether the dispersion state of the second mixture is qualified. In response to the qualified dispersion state of the second mixture, the second mixture is subjected to a second washing treatment and then dried to obtain a dry quartz sand filter cake, and then subjected to sodium ion removal treatment to obtain the sodium ion content and surface hydroxyl concentration in the dry quartz sand filter cake after sodium ion removal treatment. The grafting coefficient is determined based on the surface hydroxyl concentration and the sodium ion content, and compared with a preset grafting coefficient to determine the organosilane solution spraying treatment strategy to obtain the finished quartz sand. The preset solid-liquid ratio is the weight ratio of quartz sand raw material to water glass solution of 1:2 to 1:3, and the preset temperature range is 40℃ to 60℃. The dispersion coefficient is the product of the ratio of the initial viscosity to the real-time viscosity of the second mixture and the ratio of the initial particle size to the real-time particle size of the second mixture. The grafting coefficient is the product of the ratio of the measured surface hydroxyl concentration of the dry quartz sand filter cake to the reference hydroxyl concentration, and the ratio of the measured sodium ion content of the dry quartz sand filter cake to the reference sodium ion content.

2. The method for preparing high-purity quartz sand using organosilane and water glass according to claim 1, characterized in that, Based on the fact that the conductivity is less than a preset conductivity, the first washing process is determined to have met the standard. The first washing process involves intermittent stirring, with 3 to 5 washing cycles. The mass ratio of ultrapure water to the first mixture is 2:1 to 3:1 for each washing cycle. The washing temperature is 25°C to 40°C, and the stirring time for each washing cycle is 10 to 15 minutes. After standing for 10 to 20 minutes to allow sedimentation, the supernatant is separated.

3. The method for preparing high-purity quartz sand using organosilane and water glass according to claim 1, characterized in that, The dispersion state of the second mixture is determined to be qualified based on the dispersion coefficient being greater than or equal to the preset dispersion coefficient.

4. The method for preparing high-purity quartz sand using organosilane and water glass according to claim 1, characterized in that, Based on the grafting coefficient being greater than or equal to a preset grafting coefficient, the organosilane solution spray treatment strategy is determined as the first treatment strategy, wherein... The first processing strategy involves placing the dry quartz sand filter cake in a fluidized bed spray coating machine, preheating it to 110℃~130℃, and spraying it with an organosilane solution at a spray rate of 0.5mL / min~1.0mL / min for 20~30 minutes. The sprayed quartz sand is then cured at a curing temperature of 150℃~180℃ for 60~90 minutes to obtain the finished quartz sand.

5. The method for preparing high-purity quartz sand using organosilane and water glass according to claim 4, characterized in that, Based on the fact that the grafting coefficient is less than a preset grafting coefficient, the organosilane solution spray treatment strategy is determined to be the second treatment strategy, wherein... The second processing strategy involves placing the dry quartz sand filter cake in a fluidized bed spray coating machine, preheating it to 110℃~130℃, and spraying an organosilane solution at a spray rate of 0.5mL / min~1.0mL / min for 20~30 minutes. While maintaining the preheated temperature, a nitrogen atmosphere containing 0.5%~1.0% ammonia is introduced for 30~45 minutes. The quartz sand after the atmosphere is introduced is then cured at a curing temperature of 150℃~180℃ for 60~90 minutes to obtain the finished quartz sand.

6. The method for preparing high-purity quartz sand using organosilane and water glass according to claim 1, characterized in that, The water glass solution is sodium water glass (Na2O·nSiO2) with a modulus of 3.0–3.4 and a concentration of 30%–40% by mass fraction of silicon dioxide. Before use, it is filtered through a 0.45 μm filter membrane to remove impurities.

7. The method for preparing high-purity quartz sand using organosilane and water glass according to claim 5, characterized in that, The organosilane solution comprises the following components: 5%–10% alkoxysilane by mass, 85%–92% anhydrous ethanol, 2%–5% deionized water, and 0.5%–1.5% glacial acetic acid by mass of the alkoxysilane. The alkoxysilane is one or more of methyltrimethoxysilane, vinyltriethoxysilane, and γ-aminopropyltriethoxysilane.

8. The method for preparing high-purity quartz sand using organosilane and water glass according to claim 1, characterized in that, The acid solution is a mixture of hydrochloric acid with a mass fraction of 5% to 15% and hydrofluoric acid with a mass fraction of 1% to 5%, with a volume ratio of hydrochloric acid to hydrofluoric acid of 5:1 to 10:1, and a solid-liquid mass ratio of the wet quartz sand filter cake to the acid solution of 1:2 to 1:

4.

9. The method for preparing high-purity quartz sand using organosilane and water glass according to claim 1, characterized in that, The reaction process involves mixing quartz sand raw material with ultrapure water at a solid-liquid ratio of 1:0.3 to 1:0.5, stirring at a speed of 100 rpm to 150 rpm for 5 to 10 minutes, preheating the water glass solution to 60°C to 70°C, increasing the stirring speed to 300 rpm to 400 rpm, and adding it uniformly to the quartz sand raw material over 10 to 15 minutes using a constant flow pump. After the water glass solution is added, the temperature is raised to 70°C to 80°C, maintaining a stirring speed of 300 rpm to 400 rpm for 90 minutes.

10. The method for preparing high-purity quartz sand using organosilane and water glass according to claim 1, characterized in that, The sodium ion removal process involves mixing dried silica sand filter cake with ammonium-type strong acid cation exchange resin at a mass ratio of 10:1 to 20:1, placing the mixture in a rotary reactor, and heating it from room temperature to 300°C to 400°C at a rate of 5°C / min under a nitrogen protective atmosphere. The temperature is maintained for 60 to 120 minutes, and the mixture is then naturally cooled to below 80°C. A vibrating screen is used to separate the silica sand from the ion exchange resin.

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