Method for preparing high-purity quartz sand by taking organic silicon as raw material through combustion

Abstract

The invention relates to a method for preparing high-purity quartz sand by burning organic silicon as a raw material, and belongs to the technical field of synthesis of quartz sand. The method comprises the following steps: introducing purified organic silicon into a combustor, and combusting to obtain nano silicon dioxide powder; then sintering is carried out to remove moisture, hydroxyl and carbon impurities on the surface of the powder, sintered silicon dioxide powder is obtained, and acid leaching and cleaning are carried out to remove metal impurities on the surface and in the powder; roasting the cleaned silicon dioxide powder in a chlorine atmosphere to remove moisture, hydroxyl and residual metal impurities; and carrying out high-temperature densification treatment on the roasted silicon dioxide powder, and then crushing, grinding and screening to obtain the high-purity quartz sand. The particle size of the prepared high-purity quartz sand ranges from 50 micrometers to 300 micrometers, the purity is larger than or equal to 99.999%, and the apparent density is larger than or equal to 2.1 g / cm < 3 >. The method breaks through the limitation of natural mineral purification, and provides a brand new path for large-scale production of high-added-value quartz sand.

Description

Technical Field

[0001] The present invention 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 a raw material. Background Art

[0002] Quartz sand, a key industrial raw material, is widely used in technologies such as semiconductors, fiber-optic communications, photovoltaics, and optical devices. With the rapid development of these industries, the demand for high-purity quartz sand (SiO2 purity ≥99.998%) is growing, particularly with stringent requirements for controlling metallic impurities (such as Fe, Al, and Li) and air bubble inclusions. Traditional methods for producing high-purity quartz sand rely primarily on the purification of natural crystal or high-grade quartzite, but this process has significant drawbacks: First, raw material limitations. High-quality crystal ore resources are becoming increasingly depleted and geographically uneven, limiting the supply of raw materials to natural conditions. Second, there are purification bottlenecks. The combined physical beneficiation and chemical pickling process is inefficient in removing trace impurities such as boron and phosphorus, making it difficult to achieve a purity level exceeding 99.995%. Third, energy consumption and pollution are significant. Processes such as multi-stage crushing and high-temperature chlorination roasting consume high energy and generate large amounts of waste acid containing fluorine and chlorine, placing significant environmental pressures.

[0003] In recent years, the synthetic preparation of high-purity quartz sand has become a research hotspot. While chemical vapor deposition (CVD) and sol-gel methods can achieve high purity, they suffer from complex equipment, high costs, and low yields. Organosilicon compounds (such as hexamethyldisiloxane and ethyl orthosilicate) are considered ideal precursors for synthetic quartz sand due to their controllable molecular structure and ease of purification to ppt-level impurity levels. However, existing combustion synthesis technology still has the following technical pain points: First, the combustion of organosilicon raw materials produces water vapor, resulting in a high hydroxyl content in the product; second, incomplete combustion results in residual free carbon or Si-C bonds, affecting product purity; and third, the particle size is too small (nanoscale) and uncontrollable, resulting in severe product agglomeration, making it difficult to directly meet photovoltaic and semiconductor-grade particle size distribution requirements.

[0004] In view of the above shortcomings and deficiencies of traditional quartz ore purification and existing combustion method for synthesizing quartz sand, it is urgent to provide a 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 The invention discloses a method for preparing high-purity quartz sand. Summary of the Invention

[0005] In order to solve the technical problems of low purity, small particle size and uncontrollable silica powder produced by existing combustion methods, the present invention provides a method for producing high-purity quartz sand by combustion using organosilicon as raw material. The present invention proposes to use high-purity organosilicon (purity ≥99.99%) as raw material, and through raw material purification, combustion temperature control and process optimization, to achieve in-situ purification and size and density control of combustion products, thereby producing high-purity quartz sand with a purity ≥99.999%, a particle size of 50 μm to 300 μm, and an apparent density ≥2.1 g / cm 3 This method breaks through the inherent limitations of natural mineral purification and provides a new path for the large-scale production of high-value-added quartz sand.

[0006] The present invention is achieved through the following technical solutions: The object of the present invention is to provide a method for preparing high-purity quartz sand by burning organic silicon as a raw material, comprising the following steps: (1) Introducing the purified organosilicon into a burner and burning it to obtain nano-silicon dioxide powder; (2) Sintering the obtained silica powder to remove moisture, hydroxyl groups and carbon impurities on the powder surface to obtain sintered silica powder, which is then acid-leached and cleaned to remove metal impurities on the powder surface and inside; (3) calcining the cleaned silica powder in a chlorine atmosphere to remove moisture, hydroxyl groups and residual metal impurities to obtain calcined silica powder; (4) The calcined silica powder is subjected to high-temperature densification treatment, and then crushed, ground and sieved to obtain high-purity quartz sand.

[0007] In one embodiment of the present invention, in step (1), the organosilicon is a combustible substance composed of one or more of carbon, hydrogen and oxygen and silicon; the organosilicon is one or more of monosilane, hexamethyldisiloxane, octamethylcyclotetrasiloxane and ethyl orthosilicate; and / or the purity of the purified organosilicon is ≥99.99%; And / or, the heat is changed to heating to boiling point in a water bath or an oil bath.

[0008] In one embodiment of the present invention, in step (1), the purified organic silicon is thermally converted into steam, which is introduced into a burner with argon as a carrier gas and burned to obtain nano-silicon dioxide powder; Alternatively, the pressure difference formed by the high-speed airflow is used to suck the organic silicon liquid into the main pipe to form a gas-liquid mixture, which is then introduced into the burner and burned to obtain nano-silicon dioxide powder.

[0009] In one embodiment of the present invention, in step (1), the combustion temperature is 800°C to 2500°C; and / or, the combustion atmosphere is one or more of air, oxygen and hydrogen; And / or, the combustion is ejected from the burner outlet in the form of a mixed gas to generate nano-silicon dioxide powder; or, the liquid silicone is sucked into the burner by high-pressure airflow suction, ejected from the burner outlet, and atomized into fine droplets and then burned to generate nano-silicon dioxide powder.

[0010] In one embodiment of the present invention, in step (1), the particle size of the nano-silica powder is 10 nm to 200 nm; And / or, the purity of the nano-silicon dioxide powder is ≥99.999%.

[0011] In one embodiment of the present invention, in step (2), the sintering temperature is 800°C to 1200°C; And / or, the sintering time is ≥4 h.

[0012] In one embodiment of the present invention, in step (2), the acid solution for pickling 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% to 10%; the mass concentration of the hydrofluoric acid is 1% to 5%; the mass concentration of the oxalic acid is 1% to 5%; the volume ratio of the hydrochloric acid to the hydrofluoric acid is 2:1 to 5:1; and the volume ratio of the hydrochloric acid to the oxalic acid is 3:1 to 10:1.

[0013] In one embodiment of the present invention, in step (2), the mass ratio of the sintered silica powder to the acid leaching acid solution is 1:2 to 1:5; And / or, the cleaning includes cleaning with an alkaline solution and cleaning with water.

[0014] In one embodiment of the present invention, 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%; And / or, the calcination temperature is 800° C. to 1200° C.; And / or, the calcination time is 1 h to 4 h; And / or, a carbon source is further added during the roasting; the amount of the carbon source added is 5% to 10% of the silica powder; and the carbon source is selected from coke and / or petroleum coke.

[0015] In one embodiment of the present invention, in step (4), the high-temperature densification treatment is a three-stage insulation program: the temperature of the first insulation program is 1000°C~1200°C, and the time is 6 h~10 h; the temperature of the second insulation program is 1300°C~1600°C, and the time is 4 h~6 h; the temperature of the third insulation program is 1750°C~2000°C, and the time is 2 h~4 h.

[0016] The present invention also provides high-purity quartz sand prepared by the method, wherein the particle size of the high-purity quartz sand is 50 μm to 300 μm; the purity is ≥99.999% and the apparent density is ≥2.1 g / cm 3 .

[0017] The above technical solution of the present invention has the following advantages over the prior art: This invention provides a method for producing high-purity quartz sand by combustion using high-purity organosilicon as a raw material, which offers significant advantages over traditional processes. By utilizing organosilicon raw materials with a purity of ≥99.99%, combined with an optimized combustion process (800°C-2500°C) and multi-stage purification (acid leaching, chlorine roasting, and gradient sintering), this method successfully produces high-quality quartz sand with a purity of ≥99.999% and a particle size of 50 μm-300 μm. The metal impurity content is less than 0.1 ppm. This method not only overcomes the purity limitations of traditional mineral purification methods (upper limit of 99.995%) and the problems of existing combustion methods, such as residual free carbon or Si-C bonds, hydroxyl groups and metal impurities, and uncontrollable particle size, but also offers advantages such as low energy consumption (reduced by more than 30%), environmental friendliness (enabling closed-loop treatment of hazardous substances), and a stable raw material source. This method provides a high-performance and cost-effective solution for producing high-purity quartz sand for applications in photovoltaics, semiconductors, fiber optic communications, and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein: Figure 1 It is a flow chart for preparing high-purity quartz sand in the present invention. DETAILED DESCRIPTION

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0020] The present invention provides a method for preparing high-purity quartz sand by burning organic silicon as a raw material. First, the organic silicon raw material is purified to a relatively high purity, and then the organic silicon raw material is sent to a burner by a suitable method for combustion to produce high-purity nano-silicon dioxide powder. Then, the powder produced by the combustion is collected and sintered at high temperature to remove moisture, hydroxyl groups and incompletely oxidized carbon impurities on the surface of the powder. Secondly, the sintered silicon dioxide powder is acid-leached to further remove metal impurities on the surface and inside the powder. The powder after acid leaching is washed with an alkaline solution to neutralize the residual acid and repeatedly washed with deionized water multiple times. Then, the powder is sent to a chlorine atmosphere furnace for roasting to further remove moisture, hydroxyl groups and residual metal impurities, and is again washed multiple times with deionized water. Finally, the powder is heated in an electric furnace and subjected to high-temperature densification treatment, and the obtained quartz block material is crushed, ground and sieved to obtain high-purity quartz sand.

[0021] In the above solution, the organosilicon is a combustible substance composed of silicon and one or more of carbon, hydrogen and oxygen, including but not limited to monosilane, hexamethyldisiloxane, octamethylcyclotetrasiloxane and ethyl orthosilicate.

[0022] In the above scheme, the purity of the purified organosilicon is ≥99.99%, and the combustion of the organosilicon is gas-phase combustion or liquid-phase combustion. In gas-phase combustion, the organosilicon vapor is heated in a water bath or oil bath and then carried by a carrier gas into the burner, and then ejected from the burner outlet and burned to generate silica powder; in liquid-phase combustion, the liquid organosilicon is sucked into the burner by high-pressure airflow and then ejected from the burner outlet at high speed, atomized into fine droplets, and then burned to generate silica powder.

[0023] In the above scheme, the organosilicon is burned alone or mixed with hydrogen in air or oxygen at a combustion temperature of 800°C to 2500°C. The particle size of the silica powder is between 10 nm and 200 nm, and the purity is above 99.999%.

[0024] In the above solution, the sintering temperature of the silicon dioxide powder is controlled at 800° C. to 1200° C., and the sintering time is more than 4 hours.

[0025] In the above scheme, when the sintered silica powder is subjected to acid leaching 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% to 10% (mass fraction), the concentrations of hydrofluoric acid and oxalic acid are 1% to 5% (mass fraction), the volume ratio of hydrochloric acid to hydrofluoric acid is 2:1 to 5:1, the volume ratio of hydrochloric acid to oxalic acid is 3:1 to 10:1, and the mass ratio of silica powder to acid solution is 1:2 to 1:5.

[0026] In the above scheme, the silicon dioxide powder is acid-leached and then calcined at high temperature in chlorine. A carbon source (such as coke, petroleum coke) is added as a reducing agent during the calcination, and the proportion is about 5% to 10% of the mass of the quartz sand. The calcination temperature is 800°C to 1200°C, and the calcination time is 1 h to 4 h. The chlorine concentration is pure chlorine or a Cl2 / N2 mixed gas (Cl2 accounts for 20% to 100%). Volatile chlorides (such as FeCl3, AlCl3) are recovered by condensation or absorbed by alkali solution (such as NaOH).

[0027] In the above scheme, the silica powder is calcined in chlorine and then subjected to high-temperature densification treatment. The high-temperature densification treatment undergoes three insulation procedures, wherein the first insulation temperature is between 1000°C and 1200°C, the insulation time is between 6 h and 10 h, the second insulation temperature is between 1300°C and 1600°C, the insulation time is between 4 h and 6 h, and the third insulation temperature is between 1750°C and 2000°C, and the insulation time is between 2 h and 4 h.

[0028] In the above scheme, the purity of the high-purity quartz sand prepared by burning high-purity organic silicon is ≥99.999% and the apparent density is ≥2.1 g / cm 3 , particle size is 50 μm~300 μm.

[0029] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are all commercially available unless otherwise specified.

[0030] The CAS number of hexamethyldisiloxane is 107-46-0; the CAS number of hydrochloric acid is 7647-01-0; the CAS number of oxalic acid is 144-62-7; the CAS number of hydrofluoric acid is 7664-39-3; the CAS number of coke is 65996-77-2; and the CAS number of petroleum coke is 64743-05-1.

[0031] Example 1:

[0032] Reference Figure 1 The present invention provides a method for preparing high-purity quartz sand by burning high-purity organic silicon as raw material, and the specific steps are as follows: (1) After hexamethyldisiloxane is purified to a purity of 99.99%, it is heated to boiling point in an oil bath and introduced into a burner using argon as a carrier gas. Hexamethyldisiloxane burns in air to produce high-purity nano-silica powder. The combustion temperature is around 1000°C. 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 , with a purity of 99.999%.

[0033] (2) The high-purity nano-silica 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 to obtain sintered silica powder.

[0034] (3) The sintered silica powder was acid-leached with a mixed aqueous solution of hydrochloric acid and oxalic acid, wherein the concentration of hydrochloric acid was 3% (mass fraction), the concentration of oxalic acid was 3% (mass fraction), the volume ratio of hydrochloric acid to oxalic acid was 3:1, and the mass ratio of the sintered silica powder to the acid solution was 1:3. The acid-leached powder was washed with an alkaline solution of sodium hydroxide to neutralize the residual acidic substances and repeatedly washed with deionized water.

[0035] (4) The powder obtained in step (3) is sent to a chlorine atmosphere furnace for roasting to further remove moisture, hydroxyl groups and residual metal impurities. Coke is added as a reducing agent during roasting, with a ratio of 5% of the mass of quartz sand. The roasting temperature is 800°C and the roasting time is 2 h. Cl2 accounts for 80% of the Cl2 / N2 mixed gas. Volatile chlorides are recovered by condensation or absorbed by alkali solution (NaOH).

[0036] (5) The chlorine-calcined silica powder obtained in step (4) is subjected to a high-temperature densification treatment, wherein the high-temperature densification treatment undergoes three insulation procedures, wherein the first insulation temperature is 1000°C and the insulation time is 8 h, the second insulation temperature is 1300°C and the insulation time is 6 h, and the third insulation temperature is 1750°C and the insulation time is 4 h.

[0037] (6) The quartz block material obtained in step (5) is crushed, ground and sieved to obtain high-purity quartz sand with a purity of 99.9992% and an apparent density of 2.16 g / cm 3 , particle size is 180 μm~300 μm.

[0038] Example 2:

[0039] This embodiment provides a method for preparing high-purity quartz sand by burning high-purity organosilicon as a raw material. The specific steps are as follows: (1) After hexamethyldisiloxane is purified to a purity of 99.99%, it is heated to boiling point in an oil bath and introduced into a burner using argon as a carrier gas. Hexamethyldisiloxane is mixed with hydrogen and burned in air to produce high-purity nano-silica powder. The combustion temperature is around 2000°C. The particle size of the silica powder is between 20 nm and 100 nm, and the density is less than 1.0 g / cm 3 , with a purity of 99.9995%.

[0040] (2) The high-purity nano-silica 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.

[0041] (3) The sintered silica powder was acid-leached with a mixed aqueous solution of hydrochloric acid and oxalic acid, wherein the concentration of hydrochloric acid was 3% (mass fraction), the concentration of oxalic acid was 3% (mass fraction), the volume ratio of hydrochloric acid to oxalic acid was 3:1, and the mass ratio of the sintered silica powder to the acid solution was 1:2. The acid-leached powder was washed with an alkaline solution of sodium hydroxide to neutralize the residual acidic substances and repeatedly washed with deionized water.

[0042] (4) The powder obtained in step (3) is sent to a chlorine atmosphere furnace for roasting to further remove moisture, hydroxyl groups and residual metal impurities. Coke is added as a reducing agent during roasting, with a ratio of 5% of the mass of quartz sand. The roasting temperature is 800°C and the roasting time is 2 h. Cl2 accounts for 80% of the Cl2 / N2 mixed gas. Volatile chlorides are recovered by condensation or absorbed by alkali solution (NaOH).

[0043] (5) The chlorine-calcined silica powder obtained in step (4) is subjected to a high-temperature densification treatment, wherein the high-temperature densification treatment undergoes three insulation procedures, wherein the first insulation temperature is 1000°C and the insulation time is 8 h, the second insulation temperature is 1300°C and the insulation time is 6 h, and the third insulation temperature is 1750°C and the insulation time is 4 h.

[0044] (6) The quartz block material obtained in step (5) is crushed, ground and sieved to obtain high-purity quartz sand with a purity of 99.9995% and an apparent density of 2.14 g / cm 3 , particle size is 50 μm~200 μm.

[0045] Example 3:

[0046] This embodiment provides a method for preparing high-purity quartz sand by burning high-purity organosilicon as a raw material. The specific steps are as follows: (1) After hexamethyldisiloxane is purified to a purity of 99.99%, it is heated to boiling point in an oil bath and introduced into a burner using argon as a carrier gas. Hexamethyldisiloxane burns in air to produce high-purity nano-silica powder. The combustion temperature is around 1000°C. 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 , with a purity of 99.999%.

[0047] (2) The high-purity nano-silica 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.

[0048] (3) The sintered silica powder was acid-leached with a mixed aqueous solution of hydrochloric acid and oxalic acid, wherein the concentration of hydrochloric acid was 3% (mass fraction), the concentration of oxalic acid was 3% (mass fraction), the volume ratio of hydrochloric acid to oxalic acid was 3:1, and the mass ratio of the sintered silica powder to the acid solution was 1:3. The acid-leached powder was washed with an alkaline solution of sodium hydroxide to neutralize the residual acidic substances and repeatedly washed with deionized water.

[0049] (4) The powder obtained in step (3) is sent to a chlorine atmosphere furnace for roasting to further remove moisture, hydroxyl groups and residual metal impurities. Carbon source coke is added as a reducing agent during roasting, with a ratio of 5% of the mass of quartz sand. The roasting temperature is 800°C and the roasting time is 2 h. Cl2 accounts for 80% of the Cl2 / N2 mixed gas. Volatile chlorides are recovered by condensation or absorbed by alkali solution (NaOH).

[0050] (5) The chlorine-calcined silica powder obtained in step (4) is subjected to a high-temperature densification treatment, wherein the high-temperature densification treatment undergoes three insulation procedures, wherein the first insulation temperature is 1000°C and the insulation time is 8 h, the second insulation temperature is 1300°C and the insulation time is 6 h, and the third insulation temperature is 1750°C and the insulation time is 4 h.

[0051] (6) The quartz block material obtained in step (5) is crushed, ground and sieved to obtain high-purity quartz sand with a purity of 99.9992% and an apparent density of 2.16 g / cm 3 , particle size is 180 μm~300 μm.

[0052] Example 4:

[0053] This embodiment provides a method for preparing high-purity quartz sand by burning high-purity organosilicon as a raw material. The specific steps are as follows: (1) After hexamethyldisiloxane is purified to a purity of 99.99%, it is heated to boiling point in an oil bath and introduced into a burner using argon as a carrier gas. Hexamethyldisiloxane burns in air to produce high-purity nano-silica powder. The combustion temperature is around 1000°C. 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 , with a purity of 99.999%.

[0054] (2) The high-purity nano-silica 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.

[0055] (3) The sintered silica powder was acid-leached with a mixed solution of hydrochloric acid and oxalic acid, wherein the hydrochloric acid concentration was 5% (mass fraction), the hydrofluoric acid concentration was 5% (mass fraction), the volume ratio of hydrochloric acid to hydrofluoric acid was 3:1, and the mass ratio of the sintered silica powder to the acid solution was 1:5. The acid-leached powder was washed with an alkaline solution of sodium hydroxide to neutralize the residual acidic substances and repeatedly washed with deionized water.

[0056] (4) The powder obtained in step (3) is sent to a chlorine atmosphere furnace for roasting to further remove moisture, hydroxyl groups and residual metal impurities. Coke is added as a reducing agent during roasting, with a ratio of 5% of the mass of quartz sand. The roasting temperature is 800°C and the roasting time is 2 h. Cl2 accounts for 80% of the Cl2 / N2 mixed gas. Volatile chlorides are recovered by condensation or absorbed by alkali solution (NaOH).

[0057] (5) The chlorine-calcined silica powder obtained in step (4) is subjected to a high-temperature densification treatment, wherein the high-temperature densification treatment undergoes three insulation procedures, wherein the first insulation temperature is 1000°C and the insulation time is 8 h, the second insulation temperature is 1300°C and the insulation time is 6 h, and the third insulation temperature is 1750°C and the insulation time is 4 h.

[0058] (6) The quartz block material obtained in step (5) is crushed, ground and sieved to obtain high-purity quartz sand with a purity of 99.9998% and an apparent density of 2.16 g / cm 3 , particle size is 50 μm~300 μm.

[0059] Example 5:

[0060] This embodiment provides a method for preparing high-purity quartz sand by burning high-purity organosilicon as a raw material. The specific steps are as follows: (1) After hexamethyldisiloxane is purified to a purity of 99.99%, it is heated to boiling point in an oil bath and introduced into a burner using argon as a carrier gas. Hexamethyldisiloxane burns in air to produce high-purity nano-silica powder. The combustion temperature is around 1000°C. 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 , with a purity of 99.999%.

[0061] (2) The high-purity nano-silica 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.

[0062] (3) The sintered silica powder was acid-leached with a mixed solution of hydrochloric acid and oxalic acid, wherein the hydrochloric acid concentration was 3% (mass fraction), the hydrofluoric acid concentration was 3% (mass fraction), the volume ratio of hydrochloric acid to hydrofluoric acid was 3:1, and the mass ratio of the sintered silica powder to the acid solution was 1:3. The acid-leached powder was washed with an alkaline solution of sodium hydroxide to neutralize the residual acidic substances and repeatedly washed with deionized water.

[0063] (4) The powder obtained in step (3) is sent to a chlorine atmosphere furnace for roasting to further remove moisture, hydroxyl groups and residual metal impurities. Coke is added as a reducing agent during roasting, with a ratio of 5% of the mass of quartz sand. The roasting temperature is 1200°C and the roasting time is 4 h. Cl2 accounts for 50% of the Cl2 / N2 mixed gas. Volatile chlorides are recovered by condensation or absorbed by alkali solution (NaOH).

[0064] (5) The chlorine-calcined silica powder obtained in step (4) is subjected to a high-temperature densification treatment, wherein the high-temperature densification treatment undergoes three insulation procedures, wherein the first insulation temperature is 1000°C and the insulation time is 8 h, the second insulation temperature is 1300°C and the insulation time is 6 h, and the third insulation temperature is 1750°C and the insulation time is 4 h.

[0065] (6) The quartz block material obtained in step (5) is crushed, ground and sieved to obtain high-purity quartz sand with a purity of 99.9995% and an apparent density of 2.16 g / cm 3 , particle size is 50 μm~300 μm.

[0066] Example 6:

[0067] This embodiment provides a method for preparing high-purity quartz sand by burning high-purity organosilicon as a raw material. The specific steps are as follows: (1) After hexamethyldisiloxane is purified to a purity of 99.999%, it is heated to boiling point in an oil bath and introduced into a burner using argon as a carrier gas. Hexamethyldisiloxane burns in air to produce high-purity nano-silica powder. The combustion temperature is around 1000°C. 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 , with a purity of 99.9999%.

[0068] (2) The high-purity nano-silica 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.

[0069] (3) The sintered silica powder was acid-leached with a mixed solution of hydrochloric acid and oxalic acid, wherein the hydrochloric acid concentration was 5% (mass fraction), the hydrofluoric acid concentration was 5% (mass fraction), the volume ratio of hydrochloric acid to hydrofluoric acid was 3:1, and the mass ratio of the sintered silica powder to the acid solution was 1:3. The acid-leached powder was washed with an alkaline solution of sodium hydroxide to neutralize the residual acidic substances and repeatedly washed with deionized water.

[0070] (4) The powder obtained in step (3) is sent to a chlorine atmosphere furnace for roasting to further remove moisture, hydroxyl groups and residual metal impurities. Coke is added as a reducing agent during roasting, with a ratio of 5% of the mass of quartz sand. The roasting temperature is 1200°C and the roasting time is 2 h. Cl2 accounts for 80% of the Cl2 / N2 mixture. Volatile chlorides are recovered by condensation or absorbed by alkali solution (NaOH).

[0071] (5) The chlorine-calcined silica powder obtained in step (4) is subjected to a high-temperature densification treatment, wherein the high-temperature densification treatment undergoes three insulation procedures, wherein the first insulation temperature is 1200°C and the insulation time is 8 h, the second insulation temperature is 1500°C and the insulation time is 6 h, and the third insulation temperature is 1800°C and the insulation time is 4 h.

[0072] (6) The quartz block material obtained in step (5) is crushed, ground and sieved to obtain high-purity quartz sand with a purity of 99.99992% and an apparent density of 2.2 g / cm 3 , particle size is 50 μm~300 μm.

[0073] Comparative Example 1: This comparative example provides a method for preparing high-purity quartz sand by burning high-purity organosilicon as raw material. The method is similar to Example 1, except that: in step (1), 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 / cm 3 , particle size is 180 μm~300 μm.

[0074] Comparative Example 2: This comparative example provides a method for preparing high-purity quartz sand by burning high-purity organosilicon as raw material. The method is similar to Example 1, except that in step (2), the sintering temperature is controlled at 500°C. 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.

[0075] Comparative Example 3: This comparative example provides a method for preparing high-purity quartz sand by burning high-purity organic silicon as a raw material. The method is similar to Example 1, except that in step (3), the sintered silicon dioxide powder is acid-leached with a hydrochloric acid aqueous solution, wherein the hydrochloric acid concentration 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.

[0076] Comparative Example 4: This comparative example provides a method for preparing high-purity quartz sand by burning high-purity organosilicon as raw material. The method is similar to Example 1, except 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.

[0077] Comparative Example 5: This comparative example provides a method for preparing high-purity quartz sand by burning high-purity organosilicon as raw material. The method is similar to Example 1, except that in step (5), the high-temperature densification treatment undergoes two insulation procedures, wherein the first insulation temperature is 1000°C for 8 hours, and the second insulation temperature is 1300°C for 6 hours. The purity of the obtained quartz sand is 99.995%, and the apparent density is 1.92 g / cm 3 , particle size ≤10 μm.

[0078] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing high-purity quartz sand by burning organic silicon as raw material, characterized in that: The following steps are involved: (1) Introducing the purified organosilicon into a burner and burning it to obtain nano-silicon dioxide powder; (2) Sintering the obtained nano-silica powder to remove moisture, hydroxyl groups and carbon impurities on the powder surface to obtain sintered silica powder, and then acid leaching and washing to remove metal impurities on the powder surface and inside; (2) calcining the cleaned silica powder in a chlorine atmosphere to remove moisture, hydroxyl groups and residual metal impurities to obtain calcined silica powder; (4) The calcined silica powder is subjected to high-temperature densification treatment, and then crushed, ground and sieved to obtain high-purity quartz sand.

2. The method according to claim 1, characterized in that In step (1), the organosilicon is a combustible substance composed of one or more of carbon, hydrogen and oxygen and silicon; And / or, the purity of the purified organosilicon is ≥99.99%.

3. The method according to claim 1, characterized in that In step (1), the combustion temperature is 800°C to 2500°C; And / or, the combustion atmosphere is one or more of air, oxygen and hydrogen.

4. The method according to claim 1, wherein In step (1), the particle size of the nano-silicon dioxide powder is 10 nm to 200 nm; And / or, the purity of the nano-silicon dioxide powder is ≥99.999%.

5. The method according to claim 1, wherein In step (2), the sintering temperature is 800°C to 1200°C; And / or, the sintering time is ≥4 h.

6. The method according to claim 1, characterized in that In step (2), the acid solution for acid leaching is a mixture of hydrochloric acid and oxalic acid or a mixture of hydrochloric acid and hydrofluoric acid.

7. The method according to claim 1, characterized in that In step (2), the mass ratio of the sintered silica powder to the acid solution for acid leaching is 1:2 to 1:

5.

8. The method according to claim 1, characterized in that 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%; And / or, the calcination temperature is 800° C. to 1200° C.; And / or, the calcination time is 1 h to 4 h; And / or, a carbon source is further added during the calcination; the amount of the carbon source added is 5% to 10% of the silica powder.

9. The method according to claim 1, characterized in that In step (4), the high-temperature densification treatment is a three-stage insulation program: the temperature of the first insulation program is 1000°C~1200°C, and the time is 6 h~10 h; the temperature of the second insulation program is 1300°C~1600°C, and the time is 4 h~6 h; the temperature of the third insulation program is 1750°C~2000°C, and the time is 2 h~4 h.

10. The high-purity quartz sand prepared by the method according to any one of claims 1 to 9, characterized in that: The particle size of the high-purity quartz sand is 50 μm to 300 μm; the purity is ≥99.999% and the apparent density is ≥2.1 g / cm 3 .

Images