Method for preparing high-purity quartz sand by burning organic silicon as raw material

Abstract

The application relates to a method for preparing high-purity quartz sand by burning organic silicon as raw material, and belongs to the technical field of synthetic quartz sand. The purified organic silicon is introduced into a burner to obtain nano silicon dioxide powder by burning; then, sintering is carried out to remove water, hydroxyl and carbon impurities on the surface of the powder, thereby obtaining sintered silicon dioxide powder; acid immersion and cleaning are further carried out to remove metal impurities on the surface and in the interior of the powder; the cleaned silicon dioxide powder is calcined under a chlorine atmosphere to remove water, hydroxyl and residual metal impurities; the obtained calcined silicon dioxide powder is subjected to high-temperature densification treatment, and then is crushed, ground and screened to obtain high-purity quartz sand. The high-purity quartz sand prepared by the application has a particle size of 50-300 mu m, a purity of 99.999%, and an apparent density of 2.1 g / cm 3 . The method breaks through the limitation of natural mineral purification and provides a new path for the large-scale production of high-value-added quartz sand.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of synthetic quartz sand, in particular to a method for preparing high-purity quartz sand by burning organic silicon as raw material. BACKGROUND

[0002] As an important industrial raw material, quartz sand is widely used in the technical fields of semiconductor, optical fiber communication, photovoltaic new energy, optical devices, etc. With the rapid development of these industries, the demand for high-purity quartz sand (SiO2 purity ≥ 99.998%) is increasing, and the control requirements for metal impurities (such as Fe, Al, Li, etc.) and bubble inclusions are extremely strict. The traditional preparation method of high-purity quartz sand mainly relies on the purification of natural crystal or high-grade quartzite, but this process has the following significant defects: first, the raw material is limited. The resources of high-quality crystal mines are becoming exhausted, and the geographical distribution is uneven, so the supply of raw materials is subject to natural conditions; second, the purification bottleneck. The process of physical beneficiation combined with chemical acid washing has low removal efficiency for trace impurities such as boron and phosphorus, and it is difficult to break through the purity threshold of 99.995%; third, energy consumption and pollution. The multi-stage crushing and high-temperature chlorination roasting processes have high energy consumption and produce a large amount of waste acid containing fluorine and chlorine, which has a great environmental pressure.

[0003] In recent years, the preparation of high-purity quartz sand by synthesis has become a research hotspot. Although the chemical vapor deposition (CVD) method and the sol-gel method can achieve high purity, they have problems such as complex equipment, high cost, and low yield. Organic silicon compounds (such as hexamethyldisiloxane and tetraethyl orthosilicate) are considered to be ideal precursors for synthesizing quartz sand because of their controllable molecular structure and easy purification to ppt level impurity content. However, the existing combustion synthesis technology still has the following technical difficulties: first, the combustion of organic silicon raw materials produces water vapor, resulting in high hydroxyl content in the product; second, incomplete combustion leads to the presence of free carbon or Si-C bonds, affecting the purity of the product; third, the particle size is too small (nanoscale) and uncontrollable, and the product is severely agglomerated, making it difficult to directly meet the photovoltaic and semiconductor grade particle size distribution requirements.

[0004] In view of the above-mentioned shortcomings and deficiencies of the traditional quartz mine purification and the existing combustion method for synthesizing quartz sand, it is urgent to provide a method for preparing high-purity quartz sand with a purity of ≥ 99.999%, a particle size of 50 μm ~ 300 μm, and an apparent density of ≥ 2.1 g / cm 3 . SUMMARY

[0005] To solve the technical problems of low purity, small and uncontrollable particle size of the silica powder prepared by the existing combustion method, the application provides a method for preparing high-purity quartz sand by combustion of organic silicon as raw material. The application proposes to use high-purity organic silicon (purity ≥ 99.99%) as raw material, to realize in-situ purification, size and density control of the combustion product through raw material purification, combustion temperature regulation and process optimization, so as to prepare high-purity quartz sand with purity ≥ 99.999%, particle size of 50 μm~300 μm, and apparent density ≥ 2.1 g / cm 3 The method breaks through the congenital limitation of natural mineral purification and provides a new path for the large-scale production of high-value-added quartz sand.

[0006] The application is implemented by the following technical solutions:

[0007] The application aims to provide a method for preparing high-purity quartz sand by combustion of organic silicon as raw material, which comprises the following steps:

[0008] (1) introducing the purified organic silicon into a combustor to obtain nano-silicon dioxide powder by combustion;

[0009] (2) sintering the obtained silicon dioxide powder to remove water, hydroxyl and carbon impurities on the surface of the powder, obtaining sintered silicon dioxide powder, and then performing acid immersion and cleaning to remove metal impurities on the surface and inside of the powder;

[0010] (3) calcining the cleaned silicon dioxide powder in a chlorine atmosphere to remove water, hydroxyl and residual metal impurities, obtaining calcined silicon dioxide powder;

[0011] (4) performing high-temperature densification treatment on the obtained calcined silicon dioxide powder, and then crushing, grinding and screening to obtain high-purity quartz sand.

[0012] In an embodiment of the application, in step (1), the organic silicon is a combustible substance composed of one or more of carbon, hydrogen and oxygen elements and silicon element; the organic silicon is one or more of monosilane, hexamethyldisiloxane, octamethylcyclotetrasiloxane and tetraethyl orthosilicate;

[0013] And / or, the purity of the purified organic silicon is ≥ 99.99%;

[0014] And / or, the thermal change is heating to boiling point by water bath or oil bath.

[0015] In an embodiment of the application, in step (1), the purified organic silicon is changed into steam, and the steam is introduced into the combustor with argon gas as carrier gas to obtain nano-silicon dioxide powder by combustion;

[0016] Or, the pressure difference formed by high-speed airflow absorbs the organic silicon liquid into the main pipeline to form a gas-liquid mixture, which is then introduced into the burner to burn to obtain nano silicon dioxide powder.

[0017] In one embodiment of the present application, in step (1), the temperature of the combustion is 800-2500℃;

[0018] And / or, the combustion atmosphere is one or more of air, oxygen and hydrogen;

[0019] And / or, the combustion is in the form of mixed gas, which is sprayed out of the burner outlet to generate nano silicon dioxide powder; or, the liquid organic silicon is sucked into the burner by high-pressure airflow, and then sprayed out of the burner outlet and atomized into fine droplets to generate nano silicon dioxide powder.

[0020] In one embodiment of the present application, in step (1), the particle size of the nano silicon dioxide powder is 10-200 nm;

[0021] And / or, the purity of the nano silicon dioxide powder is ≥99.999%.

[0022] In one embodiment of the present application, in step (2), the sintering temperature is 800-1200℃;

[0023] And / or, the sintering time is ≥4 h.

[0024] In one embodiment of the present application, in step (2), the acid solution for acid immersion is a mixture of hydrochloric acid and oxalic acid or a mixture of hydrochloric acid and hydrofluoric acid, and the solvent is water; the mass concentration of the hydrochloric acid is 1-10%; the mass concentration of the hydrofluoric acid is 1-5%; the mass concentration of the oxalic acid is 1-5%; the volume ratio of the hydrochloric acid to the hydrofluoric acid is 2:1-5:1; the volume ratio of the hydrochloric acid to the oxalic acid is 3:1-10:1.

[0025] In one embodiment of the present application, in step (2), the mass ratio of the sintered silicon dioxide powder to the acid solution for acid immersion is 1:2-1:5;

[0026] And / or, the cleaning includes alkaline solution cleaning and water cleaning.

[0027] In one embodiment of the present application, in step (3), the gas in the chlorine atmosphere is a mixed gas of chlorine and nitrogen; the volume ratio of chlorine in the mixed gas is ≥50%;

[0028] And / or, the calcination temperature is 800-1200℃;

[0029] And / or, the calcination time is 1-4 h.

[0030] And / or, a carbon source is added during the roasting process; the amount of carbon source added is 5% to 10% of the silica powder; the carbon source is selected from coke and / or petroleum coke.

[0031] In one embodiment of the present invention, in step (4), the high-temperature densification process is a three-stage heat preservation process: the temperature of the first heat preservation process is 1000℃~1200℃ and the time is 6 h~10 h; the temperature of the second heat preservation process is 1300℃~1600℃ and the time is 4 h~6 h; the temperature of the third heat preservation process is 1750℃~2000℃ and the time is 2 h~4 h.

[0032] The present invention also provides high-purity quartz sand prepared by the method, wherein the high-purity quartz sand has a particle size of 50 μm to 300 μm, a purity of ≥99.999%, and an apparent density of ≥2.1 g / cm³. 3 .

[0033] The technical solution of the present invention has the following advantages compared with the prior art:

[0034] This invention provides a method for preparing high-purity quartz sand using high-purity organosilicon as raw material through combustion, which has significant advantages over traditional processes. By using organosilicon raw materials with a purity ≥99.99%, combined with an optimized combustion process (800℃-2500℃) and multi-stage purification treatment (acid leaching, chlorine roasting, and gradient sintering), this invention successfully prepares high-quality quartz sand with a purity ≥99.999% and a particle size of 50 μm~300 μm, with a metal impurity content of less than 0.1 ppm. This method not only solves the problems of purity limitations (upper limit of 99.995%) in traditional mineral purification methods and the uncontrollable issues of residual free carbon or Si-C bonds, hydroxyl groups, metal impurities, and particle size in existing combustion methods, but also has advantages such as low energy consumption (reduced by more than 30%), good environmental performance (achieving closed-loop treatment of harmful substances), and stable raw material sources. It provides a high-performance and cost-effective high-purity quartz sand preparation solution for photovoltaic, semiconductor, and fiber optic communication fields. Attached Figure Description

[0035] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0036] Figure 1 This is a flowchart illustrating the preparation process of high-purity quartz sand in this invention. Detailed Implementation

[0037] The application will be further described in conjunction with the drawings and specific embodiments so that those skilled in the art can better understand the application and implement it, but the embodiments are not limiting to the application.

[0038] The application provides a method for preparing high-purity quartz sand by burning organic silicon as raw material. First, the organic silicon raw material is purified to a higher purity, and then the organic silicon raw material is sent into a burner for burning by a suitable method, and high-purity nanometer silicon dioxide powder is generated. Then, the powder generated by burning is collected and high-temperature sintering is performed to remove the water, hydroxyl and incomplete carbon impurities on the surface of the powder. Second, the sintered silicon dioxide powder is subjected to acid immersion to further remove the metal impurities on the surface and inside of the powder, the powder after acid immersion is cleaned with an alkaline solution to neutralize the residual acid, and is repeatedly cleaned with deionized water for multiple times. Next, the powder is sent into a chlorine gas atmosphere furnace for roasting to further remove water, hydroxyl and residual metal impurities, and is again cleaned with deionized water for multiple times. Finally, the powder is heated in an electric furnace and subjected to high-temperature densification treatment, and the obtained quartz bulk material is crushed, ground and sieved to obtain high-purity quartz sand.

[0039] In the above scheme, the organic silicon is a combustible substance composed of silicon elements and one or more of carbon elements, hydrogen elements and oxygen elements, including but not limited to monosilane, hexamethyldisiloxane, octamethylcyclotetrasiloxane and tetraethyl orthosilicate.

[0040] In the above scheme, the purity of the purified organic silicon is ≥99.99%, and the organic silicon is burned in a gas phase or a liquid phase. In the gas phase combustion, the organic silicon vapor is heated by a water bath or an oil bath, then carried into the burner by a carrier gas, and then sprayed out of the burner outlet and burned to generate silicon dioxide powder. In the liquid phase combustion, the liquid organic silicon is sucked into the burner by high-pressure airflow, then shot out of the burner outlet at high speed, and then burned to generate silicon dioxide powder after being atomized into fine droplets.

[0041] In the above scheme, the organic silicon is burned alone in air or oxygen or burned with hydrogen mixed, the combustion temperature is 800-2500℃, the particle size of the silicon dioxide powder is 10-200 nm, and the purity is above 99.999%.

[0042] In the above scheme, the sintering temperature of the silicon dioxide powder is controlled at 800-1200℃, and the sintering time is above 4h.

[0043] In the above scheme, when the sintered silica powder is subjected to acid immersion treatment, the acid solution used is a mixed solution of hydrochloric acid and hydrofluoric acid or oxalic acid, wherein the concentration of hydrochloric acid is 1-10% (mass fraction), the concentration of hydrofluoric acid and oxalic acid is 1-5% (mass fraction), the volume ratio of hydrochloric acid to hydrofluoric acid is 2:1-5:1, the volume ratio of hydrochloric acid to oxalic acid is 3:1-10:1, and the mass ratio of silica powder to acid solution is 1:2-1:5.

[0044] In the above scheme, after the acid immersion of the silica powder, high-temperature calcination of chlorine gas is performed, and a carbon source (such as coke or petroleum coke) is added as a reducing agent, with a proportion of about 5-10% of the mass of quartz sand, the calcination temperature is 800-1200℃, the calcination time is 1-4 h, and the chlorine gas concentration uses pure chlorine gas or Cl2 / N2 mixed gas (Cl2 accounts for 20-100%), and volatile chlorides (such as FeCl3 and AlCl3) are recovered by condensation or absorbed by alkaline solution (such as NaOH).

[0045] In the above scheme, after the silica powder is subjected to chlorine gas calcination, high-temperature densification treatment is performed, and the high-temperature densification treatment undergoes three-stage temperature holding procedures, wherein the first-stage temperature holding temperature is 1000-1200℃, the temperature holding time is 6-10 h, the second-stage temperature holding temperature is 1300-1600℃, the temperature holding time is 4-6 h, and the third-stage temperature holding temperature is 1750-2000℃, and the temperature holding time is 2-4 h.

[0046] In the above scheme, the high-purity quartz sand prepared by burning the high-purity organosilicon has a purity of ≥99.999%, an apparent density of ≥2.1 g / cm 3 , and a particle size of 50-300 μm.

[0047] In the following examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are commercially available unless otherwise specified.

[0048] The CAS numbers of the materials used in the following examples are as follows: hexamethyldisiloxane: 107-46-0; hydrochloric acid: 7647-01-0; oxalic acid: 144-62-7; hydrofluoric acid: 7664-39-3; coke: 65996-77-2; and petroleum coke: 64743-05-1.

[0049] Example 1:

[0050] With reference to Figure 1 , the present application provides a method for preparing high-purity quartz sand by burning high-purity organosilicon as raw material, and the specific steps are as follows:

[0051] (1) The high purity nano-silica powder is obtained by burning hexamethyldisiloxane in air, wherein the hexamethyldisiloxane is purified to a purity of 99.99%, heated to a boiling point by using an oil bath, and introduced into a burner by using argon as a carrier gas, the burning temperature is about 1000℃, the particle size of the silica powder is between 100 nm and 200 nm, and the density is less than 1.0 g / cm 3 , and the purity reaches 99.999%.

[0052] (2) The high purity nano-silica powder obtained by burning is collected and sent into an electric furnace for high-temperature sintering, the sintering temperature is controlled at 1000℃, and the sintering time is 4 h, thereby obtaining sintered silica powder.

[0053] (3) The sintered silica powder is subjected to acid immersion by using a mixed aqueous solution of hydrochloric acid and oxalic acid, the concentration of the hydrochloric acid is 3% (mass fraction), the concentration of the oxalic acid is 3% (mass fraction), the volume ratio of the hydrochloric acid to the oxalic acid is 3:1, and the mass ratio of the sintered silica powder to the acid solution is 1:3. The powder after acid immersion is cleaned by using a sodium hydroxide alkaline solution to neutralize residual acidic substances, and repeatedly cleaned multiple times by using deionized water.

[0054] (4) The powder obtained in step (3) is sent into a chlorine gas atmosphere furnace for calcination, to further remove water, hydroxyl groups and residual metal impurities, coke is added as a reducing agent in the calcination, the proportion is 5% of the mass of the quartz sand, the calcination temperature is 800℃, the calcination time is 2 h, the proportion of Cl2 in the Cl2 / N2 mixed gas is 80%, and the volatile chlorides are recovered by condensation or absorbed by an alkali solution (NaOH).

[0055] (5) The silica powder after chlorine calcination obtained in step (4) is subjected to high-temperature densification treatment, which undergoes three-stage holding procedures, wherein the first-stage holding temperature is 1000℃, the holding time is 8 h, the second-stage holding temperature is 1300℃, the holding time is 6 h, and the third-stage holding temperature is 1750℃, the holding time is 4 h.

[0056] (6) The quartz bulk material obtained in step (5) is crushed, ground and sieved to obtain high-purity quartz sand, the purity reaches 99.9992%, the apparent density reaches 2.16 g / cm 3 , and the particle size is between 180 μm and 300 μm.

[0057] Example 2:

[0058] The embodiment provides a method for preparing high-purity quartz sand by burning high-purity organosilicon as a raw material, and the specific steps are as follows:

[0059] (1) The hexamethyldisiloxane is purified to a purity of 99.99%, then heated to boiling point using an oil bath and introduced into a burner using argon as a carrier gas. The hexamethyldisiloxane is mixed with hydrogen and combusted in air to produce high-purity nanometer silicon dioxide powder. The combustion temperature is about 2000°C, the particle size of the silicon dioxide powder is between 20 nm and 100 nm, and the density is less than 1.0 g / cm 3 , and the purity is 99.9995%.

[0060] (2) The high-purity nanometer silicon dioxide powder produced by combustion is collected and sent into an electric furnace for high-temperature sintering. The sintering temperature is controlled at 1000°C, and the sintering time is 4 h.

[0061] (3) The sintered silicon dioxide powder is subjected to acid immersion using a mixed aqueous solution of hydrochloric acid and oxalic acid. The concentration of hydrochloric acid is 3% (mass fraction), the concentration of oxalic acid is 3% (mass fraction), the volume ratio of hydrochloric acid to oxalic acid is 3:1, and the mass ratio of sintered silicon dioxide powder to acid solution is 1:2. The acid- immersed powder is cleaned with a sodium hydroxide alkaline solution to neutralize residual acidic substances, and repeatedly washed with deionized water multiple times.

[0062] (4) The powder obtained in step (3) is sent into a chlorine gas atmosphere furnace for calcination to further remove water, hydroxyl groups, and residual metal impurities. Coke is added as a reducing agent during calcination, with a proportion of 5% of the mass of quartz sand. The calcination temperature is 800°C, the calcination time is 2 h, the Cl2 proportion in Cl2 / N2 mixed gas is 80%, and volatile chlorides are recovered by condensation or absorbed by alkaline solution (NaOH).

[0063] (5) The silicon dioxide powder after chlorine calcination in step (4) is subjected to high-temperature densification treatment, which undergoes three-stage temperature holding procedures. The first-stage temperature holding temperature is 1000°C, the holding time is 8 h, the second-stage temperature holding temperature is 1300°C, the holding time is 6 h, and the third-stage temperature holding temperature is 1750°C, the holding time is 4 h.

[0064] (6) The quartz bulk material obtained in step (5) is crushed, ground, and sieved to obtain high-purity quartz sand with a purity of 99.9995%, an apparent density of 2.14 g / cm 3 , and a particle size of 50 μm to 200 μm.

[0065] Example 3:

[0066] This embodiment provides a method for preparing high-purity quartz sand by combustion using high-purity organosilicon as raw material, and the specific steps are as follows:

[0067] (1) The hexamethyldisiloxane is purified to a purity of 99.99%, then heated to boiling point using an oil bath and introduced into a burner using argon as a carrier gas, the hexamethyldisiloxane is combusted in air to produce high-purity nanometer silicon dioxide powder, the combustion temperature is about 1000℃, the particle size of the silicon dioxide powder is between 100 nm and 200 nm, and the density is less than 1.0 g / cm 3 , and the purity reaches 99.999%.

[0068] (2) The high-purity nanometer silicon dioxide powder produced by combustion is collected and sent into an electric furnace for high-temperature sintering, the sintering temperature is controlled at 1200℃, and the sintering time is 6 h.

[0069] (3) The sintered silicon dioxide powder is subjected to acid immersion using a mixed aqueous solution of hydrochloric acid and oxalic acid, the concentration of the hydrochloric acid is 3% (mass fraction), the concentration of the oxalic acid is 3% (mass fraction), the volume ratio of the hydrochloric acid to the oxalic acid is 3:1, and the mass ratio of the sintered silicon dioxide powder to the acid solution is 1:3. The powder after acid immersion is cleaned with a sodium hydroxide alkaline solution to neutralize residual acidic substances, and repeatedly cleaned with deionized water for multiple times.

[0070] (4) The powder obtained in step (3) is sent into a chlorine gas atmosphere furnace for calcination to further remove water, hydroxyl groups and residual metal impurities, carbon source coke is added as a reducing agent in the calcination, the proportion is 5% of the mass of the quartz sand, the calcination temperature is 800℃, the calcination time is 2 h, the Cl2 proportion in the Cl2 / N2 mixed gas is 80%, and the volatile chlorides are recovered by condensation or absorbed by alkaline solution (NaOH).

[0071] (5) The silicon dioxide powder after chlorine calcination obtained in step (4) is subjected to high-temperature densification treatment, which undergoes three-stage holding procedures, wherein the first-stage holding temperature is 1000℃, the holding time is 8 h, the second-stage holding temperature is 1300℃, the holding time is 6 h, and the third-stage holding temperature is 1750℃, the holding time is 4 h.

[0072] (6) The quartz bulk material obtained in step (5) is crushed, ground and sieved to obtain high-purity quartz sand, the purity reaches 99.9992%, the apparent density reaches 2.16 g / cm 3 , and the particle size is between 180 μm and 300 μm.

[0073] Example 4:

[0074] The embodiment provides a method for preparing high-purity quartz sand by combusting high-purity organosilicon as a raw material, and the specific steps are as follows:

[0075] (1) The high purity nano-silicon dioxide powder is produced by burning hexamethyldisiloxane in air, the combustion temperature is about 1000℃, the particle size of the silicon dioxide powder is between 100 nm and 200 nm, and the density is less than 1.0 g / cm 3 , and the purity reaches 99.999%.

[0076] (2) The high purity nano-silicon dioxide powder produced by combustion is collected and sent into an electric furnace for high-temperature sintering, the sintering temperature is controlled at 1000℃, and the sintering time is 4 h.

[0077] (3) The sintered silicon dioxide powder is subjected to acid immersion with a mixed solution of hydrochloric acid and oxalic acid, the concentration of hydrochloric acid is 5% (mass fraction), the concentration of hydrofluoric acid is 5% (mass fraction), the volume ratio of hydrochloric acid to hydrofluoric acid is 3:1, and the mass ratio of the sintered silicon dioxide powder to the acid solution is 1:5. The powder after acid immersion is cleaned with a sodium hydroxide alkaline solution to neutralize the residual acidic substances, and is repeatedly cleaned with deionized water for multiple times.

[0078] (4) The powder obtained in step (3) is sent into a chlorine gas atmosphere furnace for calcination to further remove water, hydroxyl groups and residual metal impurities, coke is added as a reducing agent in the calcination, the proportion is 5% of the mass of quartz sand, the calcination temperature is 800℃, the calcination time is 2 h, the proportion of Cl2 in the Cl2 / N2 mixed gas is 80%, and the volatile chlorides are recovered by condensation or absorbed by alkaline solution (NaOH).

[0079] (5) The silicon dioxide powder after chlorine calcination in step (4) is subjected to high-temperature densification treatment, which undergoes three-stage temperature holding procedures, the first-stage temperature holding temperature is 1000℃, the temperature holding time is 8 h, the second-stage temperature holding temperature is 1300℃, the temperature holding time is 6 h, and the third-stage temperature holding temperature is 1750℃, the temperature holding time is 4 h.

[0080] (6) The quartz bulk material obtained in step (5) is crushed, ground and sieved to obtain high-purity quartz sand, the purity reaches 99.9998%, the apparent density reaches 2.16 g / cm 3 , and the particle size is between 50 μm and 300 μm.

[0081] Example 5:

[0082] The embodiment provides a method for preparing high-purity quartz sand by burning high-purity organosilicon as raw material, and the specific steps are as follows:

[0083] (1) The high purity nano-silicon dioxide powder is obtained by burning the high purity hexamethyldisiloxane in air, the combustion temperature is about 1000℃, the particle size of the silicon dioxide powder is between 100 nm and 200 nm, and the density is less than 1.0 g / cm 3 , and the purity reaches 99.999%.

[0084] (2) The high purity nano-silicon dioxide powder obtained by burning is collected and sent into an electric furnace for high temperature sintering, the sintering temperature is controlled at 1000℃, and the sintering time is 4 h.

[0085] (3) The sintered silicon dioxide powder is subjected to acid immersion with a mixed solution of hydrochloric acid and oxalic acid, the concentration of the hydrochloric acid is 3% (mass fraction), the concentration of the hydrofluoric acid is 3% (mass fraction), the volume ratio of the hydrochloric acid to the hydrofluoric acid is 3:1, and the mass ratio of the sintered silicon dioxide powder to the acid solution is 1:3. The powder after acid immersion is cleaned with a sodium hydroxide alkaline solution to neutralize the residual acidic substances, and is repeatedly cleaned with deionized water for multiple times.

[0086] (4) The powder obtained in step (3) is sent into a chlorine gas atmosphere furnace for calcination to further remove water, hydroxyl groups and residual metal impurities, coke is added as a reducing agent in the calcination, the proportion is 5% of the mass of the quartz sand, the calcination temperature is 1200℃, the calcination time is 4 h, the Cl2 proportion in the Cl2 / N2 mixed gas is 50%, and the volatile chlorides are recovered by condensation or absorbed by lye (NaOH).

[0087] (5) The silicon dioxide powder after chlorine calcination in step (4) is subjected to high temperature densification treatment, which undergoes three-stage temperature holding procedures, wherein the first-stage temperature holding temperature is 1000℃, the temperature holding time is 8 h, the second-stage temperature holding temperature is 1300℃, the temperature holding time is 6 h, and the third-stage temperature holding temperature is 1750℃, and the temperature holding time is 4 h.

[0088] (6) The quartz bulk material obtained in step (5) is crushed, ground and sieved to obtain high purity quartz sand, the purity reaches 99.9995%, the apparent density reaches 2.16 g / cm 3 , and the particle size is between 50 μm and 300 μm.

[0089] Example 6:

[0090] The embodiment provides a method for preparing high purity quartz sand by burning high purity organosilicon as raw material, and the specific steps are as follows:

[0091] (1) After the hexamethyldisiloxane is purified to a purity of 99.999%, it is heated to the boiling point using an oil bath and introduced into a burner using argon as a carrier gas, and the hexamethyldisiloxane is combusted in air to produce high-purity nanometer silicon dioxide powder, the combustion temperature is about 1000°C, the particle size of the silicon dioxide powder is between 100 nm and 200 nm, and the density is less than 1.0 g / cm 3 , and the purity reaches 99.9999%.

[0092] (2) The high-purity nanometer silicon dioxide powder produced by combustion is collected and sent into an electric furnace for high-temperature sintering, the sintering temperature is controlled at 1200°C, and the sintering time is 6 h.

[0093] (3) The sintered silicon dioxide powder is subjected to acid immersion using a mixed solution of hydrochloric acid and oxalic acid, the concentration of the hydrochloric acid is 5% (mass fraction), the concentration of the hydrofluoric acid is 5% (mass fraction), the volume ratio of the hydrochloric acid to the hydrofluoric acid is 3:1, and the mass ratio of the sintered silicon dioxide powder to the acid solution is 1:3. The powder after acid immersion is cleaned with a sodium hydroxide alkaline solution to neutralize residual acidic substances, and is repeatedly cleaned multiple times with deionized water.

[0094] (4) The powder obtained in step (3) is sent into a chlorine gas atmosphere furnace for calcination to further remove water, hydroxyl groups, and residual metal impurities, coke is added as a reducing agent during calcination, the proportion is 5% of the mass of the quartz sand, the calcination temperature is 1200°C, the calcination time is 2 h, the Cl2 proportion in the Cl2 / N2 mixed gas is 80%, and the volatile chlorides are recovered by condensation or absorbed by an alkali solution (NaOH).

[0095] (5) The silicon dioxide powder after chlorine calcination obtained in step (4) is subjected to high-temperature densification treatment, which undergoes three-stage holding procedures, the first-stage holding temperature is 1200°C, the holding time is 8 h, the second-stage holding temperature is 1500°C, the holding time is 6 h, and the third-stage holding temperature is 1800°C, the holding time is 4 h.

[0096] (6) The quartz bulk material obtained in step (5) is crushed, ground, and sieved to obtain high-purity quartz sand, the purity reaches 99.99992%, the apparent density reaches 2.2 g / cm 3 , and the particle size is between 50 μm and 300 μm.

[0097] Comparative Example 1

[0098] This comparative example provides a method for preparing high-purity quartz sand by combusting high-purity organosilicon as a raw material, which is similar to Example 1, the only difference being that in step (1), the hexamethyldisiloxane is purified to a purity of 99.0%, and the purity of the obtained quartz sand is 99.98%, and the apparent density is 2.16 g / cm3 , particle size is 180 μm~300 μm.

[0099] Comparative Example 2:

[0100] This comparative example provides a method for preparing high-purity quartz sand by burning high-purity organosilicon as raw material, which is similar to Example 1, and the only difference is that in step (2), the sintering temperature is controlled at 500℃. The purity of the obtained quartz sand is 99.99%, and the apparent density is 1.8 g / cm 3 , particle size is 80 μm~200 μm.

[0101] Comparative Example 3:

[0102] This comparative example provides a method for preparing high-purity quartz sand by burning high-purity organosilicon as raw material, which is similar to Example 1, and the only difference is that in step (3), the sintered silica powder is subjected to acid leaching with hydrochloric acid aqueous solution, and the concentration of hydrochloric acid is 5% (mass fraction). The purity of the obtained quartz sand is 99.992%, and the apparent density is 2.1 g / cm 3 , particle size is 180 μm~300 μm.

[0103] Comparative Example 4:

[0104] This comparative example provides a method for preparing high-purity quartz sand by burning high-purity organosilicon as raw material, which is similar to Example 1, and the only difference is that in step (4), the calcination time is 0.5 h. The purity of the obtained quartz sand is 99.99%, and the apparent density is 1.9 g / cm 3 , particle size is 50 μm~100 μm.

[0105] Comparative Example 5:

[0106] This comparative example provides a method for preparing high-purity quartz sand by burning high-purity organosilicon as raw material, which is similar to Example 1, and the only difference is that in step (5), the high-temperature densification treatment undergoes two-stage soaking procedures, wherein the first-stage soaking temperature is 1000℃, and the soaking time is 8 h, and the second-stage soaking temperature is 1300℃, and the soaking time is 6 h. The purity of the obtained quartz sand is 99.995%, and the apparent density is 1.92 g / cm 3 , particle size is ≤10 μm.

[0107] Obviously, the above examples are only examples for clearly illustrating, and are not limited to the embodiments. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and impossible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method for producing high purity quartz sand by combustion using organosilicon as a raw material, characterized by comprising the steps of: The method comprises the following steps: ​ (1) introducing the purified organosilicon into a burner to obtain nano-silicon dioxide powder by combustion; (2) sintering the obtained nano-silicon dioxide powder to remove water, hydroxyl and carbon impurities on the surface of the powder, obtaining sintered silicon dioxide powder, and then performing acid immersion and cleaning to remove metal impurities on the surface and inside of the powder; (3) calcining the cleaned silicon dioxide powder in a chlorine atmosphere to remove water, hydroxyl and residual metal impurities, obtaining calcined silicon dioxide powder; (4) performing high-temperature densification treatment on the obtained calcined silicon dioxide powder, and then crushing, grinding and screening to obtain high-purity quartz sand; In step (1), the particle size of the nano-silicon dioxide powder is 10 nm to 200 nm; and the purity of the nano-silicon dioxide powder is ≥99.999%; In step (2), the sintering temperature is 800°C to 1200°C; and the sintering time is ≥4 h; In step (2), the acid solution for acid immersion is a mixture of hydrochloric acid and oxalic acid or a mixture of hydrochloric acid and hydrofluoric acid; In step (3), the gas in the chlorine atmosphere is a mixture of chlorine and nitrogen; and the volume ratio of chlorine in the mixture is ≥50%; The calcination temperature is 800°C to 1200°C; A carbon source is further added in the calcination; In step (4), the high-temperature densification treatment is a three-stage holding program: the temperature of the first stage holding program is 1000°C to 1200°C, and the time is 6 h to 10 h; the temperature of the second stage holding program is 1300°C to 1600°C, and the time is 4 h to 6 h; and the temperature of the third stage holding program is 1750°C to 2000°C, and the time is 2 h to 4 h.

2. The method of claim 1, wherein, In step (1), the organosilicon is a combustible substance composed of one or more of carbon, hydrogen and oxygen elements and silicon element.

3. The method of claim 1, wherein, In step (1), the purity of the purified organosilicon is ≥99.99%.

4. The method of claim 1, wherein, In step (1), the combustion temperature is 800°C to 2500°C.

5. The method of claim 1, wherein, In step (1), the combustion atmosphere is one or more of air, oxygen and hydrogen.

6. The method of claim 1, wherein, In step (2), the mass ratio of the sintered silicon dioxide powder to the acid solution for acid immersion is 1:2 to 1:

5.

7. The method of claim 1, wherein, In step (3), the calcination time is 1 h to 4 h.

8. The method of claim 1, wherein, In step (3), the addition amount of the carbon source is 5% to 10% of the silicon dioxide powder.

9. The high purity quartz sand produced by the process of any one of claims 1 to 8, characterized in that, The high-purity quartz sand has a particle size of 50-300 μm, a purity of ≥ 99.999%, and an apparent density of ≥ 2.1 g / cm 3 .

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