A method for purifying high-purity quartz sand

Abstract

The present invention relates to a method for purifying high-purity quartz sand, and belongs to the technical field of high-purity quartz sand purification. The present invention uses acidic oxides B2O3 or SnO as flux slag agents, and determines the addition amount of flux slag agents according to B2O3-SiO2 or SnO-SiO2 binary phase diagrams; quartz sand is crushed and ball-milled into quartz sand powder, and the quartz sand powder and flux slag agents are evenly mixed to obtain a mixture; under an inert gas atmosphere, the mixture is placed in a high-temperature furnace for heating and melting and heat preservation and smelting to form a eutectic; under an inert gas atmosphere, the eutectic is slowly cooled to the eutectic point temperature of B2O3-SiO2 or SnO-SiO2 and is kept warm until the melt is completely solidified so that SiO2 precipitates and separates from the slag phase, and then cooled to room temperature with the furnace to remove the flux slag agents containing impurities. The method of the present invention greatly reduces the processing temperature of the pyro-purification process, and uses the flux slag agent to extract and remove impurities in the quartz sand, so that the quartz sand is purified.

Description

Technical Field

[0001] The invention relates to a method for purifying high-purity quartz sand, and belongs to the technical field of high-purity quartz sand purification. Background Art

[0002] High-purity quartz sand is a key industrial raw material with high application value in photovoltaics, microelectronics, advanced electro-optical sources, thin-film materials, and other fields. Due to its outstanding physical and chemical properties, such as high-temperature resistance, corrosion resistance, low thermal expansion, high insulation, and good light transmittance, high-purity quartz sand has become an irreplaceable raw material. High-purity quartz powder is a general term for quartz powder raw materials with a silica purity greater than 99.9%. Product quality grades are divided according to the silica purity, namely, low-end ω(SiO2) ≥99.9% (3N), mid-range ω(SiO2) ≥99.99% (4N), and high-end ω(SiO2) ≥99.998% (4N8).

[0003] The purification of high-purity quartz sand, whether through wet or pyrometallurgical purification, presents several challenges. The primary challenge in wet purification is effectively removing harmful impurities such as aluminum, iron, and titanium from the sand. These elements exist in the sand as oxides, which are less soluble than the silicon component, making them difficult to completely remove through simple acid washing. Furthermore, the waste acid and wastewater generated during wet purification are highly polluting and require proper disposal. Pyrometallurgical purification, on the other hand, presents significant challenges due to high energy consumption and pollution. Pyrometallurgical purification requires heating the sand to high temperatures and maintaining them for extended periods, a process that consumes significant amounts of energy. Furthermore, high-temperature calcination generates significant amounts of waste gas containing hazardous substances such as chlorides and sulfides. Direct release into the environment can have serious environmental impacts. Therefore, the purification process for high-purity quartz sand requires targeted improvements, addressing specific challenges, to achieve the dual goals of efficient sand purification and environmental protection. Summary of the Invention

[0004] In view of the serious pollution caused by waste acid and wastewater in the existing wet purification process of quartz sand and the high energy consumption and high pollution problems in the pyrochlorination roasting process, the present invention proposes a purification method for high-purity quartz sand, namely, using low-melting-point acidic oxides B2O3 or SnO as fluxing slag agents, and determining the addition amount of the fluxing slag agent according to the B2O3-SiO2 and SnO-SiO2 binary phase diagrams; quartz sand and the fluxing slag agent are eutectic through high-temperature roasting, the fluxing slag agent extracts and removes impurities in the quartz sand, and the eutectic is slowly and uniformly cooled to the eutectic point temperature and kept warm until the melt is completely solidified to cause SiO2 to precipitate and separate from the slag phase.

[0005] A method for purifying high-purity quartz sand, comprising the following steps:

[0006] (1) With acidic oxide B2O3 or SnO as flux slag agent, the amount of flux slag agent added is determined according to the B2O3-SiO2 or SnO-SiO2 binary phase diagram. When B2O3 flux slag agent is added, the amount of B2O3 added is Figure 1 ) The composition range of B2O3 and SiO2 corresponding to the liquidus line at the SiO2-rich end (the composition to the right of the eutectic point); when SnO fluxing slag is added, the amount of SnO added is SnO-SiO2 phase diagram (see Figure 2 ) The composition range of SnO and SiO2 corresponding to the liquidus line at the SiO2-rich end (the composition to the right of the eutectic point);

[0007] (2) crushing quartz sand into quartz sand powder by ball grinding, and uniformly mixing the quartz sand powder and fluxing slag to obtain a mixture;

[0008] (3) In an inert gas atmosphere, the mixture is heated and melted in a high-temperature furnace and kept at this temperature to form a eutectic;

[0009] (4) Under an inert gas atmosphere, the eutectic is slowly cooled at a uniform speed to the eutectic point temperature of B2O3-SiO2 or SnO-SiO2 and kept warm until the melt is completely solidified, and then cooled to room temperature with the furnace to remove the fluxing slag containing impurities.

[0010] The addition amount of the flux slag agent is 10-90% of the total mass of the quartz sand and the flux slag agent.

[0011] The particle size of the quartz sand powder is 150-400 meshes.

[0012] The beneficial effects of the present invention are:

[0013] (1) The present invention uses low-melting-point acidic oxides B2O3 or SnO as flux slag agents, and determines the amount of flux slag agent added based on the B2O3-SiO2 and SnO-SiO2 binary phase diagrams, which can greatly reduce the amount of flux slag agent added and achieve efficient purification of quartz sand;

[0014] (2) The fluxing slag agent of the present invention has a low melting point, which can greatly reduce the processing temperature of the pyrometallurgical purification process, and utilize the principle that the fluxing slag agent and SiO2 have similar properties to extract and remove impurities in SiO2;

[0015] (3) The present invention slowly cools the eutectic to the eutectic point at a uniform speed and keeps the temperature until the melt is completely solidified, so that SiO2 can be precipitated and separated from the slag phase, thereby purifying the quartz sand;

[0016] (4) The method of the present invention has low energy consumption, no environmental pollution, short process, easy operation, and low preparation process cost, and has great industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the B2O3-SiO2 binary phase diagram;

[0018] Figure 2 This is the SnO-SiO2 binary phase diagram. DETAILED DESCRIPTION

[0019] The present invention will be further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0020] Example 1: A method for purifying high-purity quartz sand, the specific steps are as follows:

[0021] (1) Using acidic oxide B2O3 as fluxing agent, according to the B2O3-SiO2 binary phase diagram (see Figure

[0022] 1) The amount of flux added is the B2O3 and SiO2 composition range corresponding to the liquidus at the SiO2-rich end of the B2O3-SiO2 phase diagram (the chemical composition to the right of the eutectic point);

[0023] (2) Quartz sand with a purity of 99.4% was crushed and ball-milled into quartz sand powder with an average particle size of 100 mesh, and the quartz sand powder and flux slag agent B2O3 were uniformly mixed to obtain a mixture, wherein the amount of flux slag agent B2O3 added was 10% of the total mass of the quartz sand and the flux slag agent;

[0024] (3) Under an argon atmosphere, the mixture is placed in a high-temperature furnace and heated to 800°C to melt and then kept at this temperature for 1 hour to form a eutectic;

[0025] (4) Under an argon atmosphere, the eutectic is slowly cooled to 438°C (B2O3-SiO2 eutectic point) at a uniform speed and kept warm until the melt is completely solidified. It is then cooled to room temperature with the furnace to remove the fluxing agent B2O3 containing impurities.

[0026] The purity of the purified quartz sand in this embodiment is 99.927%.

[0027] Example 2: A method for purifying high-purity quartz sand, the specific steps are as follows:

[0028] (1) Using acidic oxide B2O3 as fluxing agent, according to the B2O3-SiO2 binary phase diagram (see Figure 1 ) Determine the amount of fluxing agent to be added;

[0029] (2) Quartz sand with a purity of 99.4% was crushed and ball-milled into quartz sand powder with an average particle size of 400 mesh, and the quartz sand powder and fluxing agent (B2O3) were uniformly mixed to obtain a mixture, wherein the amount of fluxing agent B2O3 added was 60% of the total mass of the quartz sand and fluxing agent;

[0030] (3) Under an argon atmosphere, the mixture is placed in a high-temperature furnace and heated to 1000°C to melt and then kept at this temperature for 4 hours to form a eutectic;

[0031] (4) Under an argon atmosphere, the eutectic is slowly cooled to 438°C (B2O3-SiO2 eutectic point) at a uniform speed and kept warm until the melt is completely solidified, and then cooled to room temperature with the furnace to remove the fluxing agent B2O3 containing impurities;

[0032] The purity of the purified quartz sand in this embodiment is 99.992%.

[0033] Example 3: A method for purifying high-purity quartz sand, the specific steps are as follows:

[0034] (1) Using acidic oxide B2O3 as fluxing agent, according to the B2O3-SiO2 binary phase diagram (see Figure 1 ) Determine the amount of fluxing agent to be added;

[0035] (2) Quartz sand with a purity of 99.4% is crushed and ball-milled into quartz sand powder with an average particle size of 400 meshes, and the quartz sand powder and a fluxing agent (B2O3) are uniformly mixed to obtain a mixture, wherein the amount of the fluxing agent B2O3 added is 90% of the total mass of the quartz sand and the fluxing agent;

[0036] (3) Under an argon atmosphere, the mixture is placed in a high-temperature furnace and heated to 1100°C to melt and then kept at this temperature for 4 hours to form a eutectic;

[0037] (4) Under an argon atmosphere, the eutectic is slowly cooled to 438°C (B2O3-SiO2 eutectic point) at a uniform speed and kept warm until the melt is completely solidified, and then cooled to room temperature with the furnace to remove the fluxing agent B2O3 containing impurities;

[0038] The purity of the purified quartz sand in this embodiment is 99.995%.

[0039] Example 4: A method for purifying high-purity quartz sand, the specific steps are as follows:

[0040] (1) Using acidic oxide SnO as fluxing agent, according to the SnO-SiO2 binary phase diagram (see Figure 2 ), the amount of flux added is the composition range of SnO and SiO2 corresponding to the liquidus line at the SiO2-rich end of the SnO-SiO2 phase diagram (the chemical composition to the right of the eutectic point);

[0041] (2) Quartz sand with a purity of 99.4% was crushed and ball-milled into quartz sand powder with an average particle size of 100 mesh, and the quartz sand powder and fluxing agent (SnO) were uniformly mixed to obtain a mixture, wherein the amount of the fluxing agent SnO added was 75% of the total mass of the quartz sand and the fluxing agent;

[0042] (3) Under an argon atmosphere, the mixture is placed in a high-temperature furnace and heated to 1600°C to melt and then kept at this temperature for 1 hour to form a eutectic;

[0043] (4) Under an argon atmosphere, the eutectic is slowly cooled to 898°C (SnO-SiO2 eutectic point) at a uniform speed and kept warm until the melt is completely solidified. It is then cooled to room temperature with the furnace to remove the impurity-containing flux slag SnO.

[0044] The purity of the purified quartz sand in this embodiment is 99.946%.

[0045] Example 5: A method for purifying high-purity quartz sand, the specific steps are as follows:

[0046] (1) Using acidic oxide SnO as fluxing agent, according to the SnO-SiO2 binary phase diagram (see Figure 2 ) Determine the amount of fluxing agent to be added;

[0047] (2) Quartz sand with a purity of 99.4% was crushed and ball-milled into quartz sand powder with an average particle size of 300 meshes, and the quartz sand powder and fluxing agent (SnO) were uniformly mixed to obtain a mixture, wherein the amount of the fluxing agent SnO added was 84% of the total mass of the quartz sand and the fluxing agent;

[0048] (3) Under an argon atmosphere, the mixture is placed in a high-temperature furnace and heated to 1650°C to melt and then kept at this temperature for 2 hours to form a eutectic;

[0049] (4) Under an argon atmosphere, the eutectic is slowly cooled to 898°C (SnO-SiO2 eutectic point) at a uniform speed and kept warm until the melt is completely solidified. It is then cooled to room temperature with the furnace to remove the impurity-containing flux slag SnO.

[0050] The purity of the purified quartz sand in this embodiment is 99.981%.

[0051] Example 6: A method for purifying high-purity quartz sand, the specific steps are as follows:

[0052] (1) Using acidic oxide SnO as fluxing agent, according to the SnO-SiO2 binary phase diagram (see Figure 2 ) Determine the amount of fluxing agent to be added;

[0053] (2) Quartz sand with a purity of 99.4% was crushed and ball-milled into quartz sand powder with an average particle size of 400 meshes, and the quartz sand powder and fluxing agent (SnO) were uniformly mixed to obtain a mixture, wherein the amount of the fluxing agent SnO added was 90% of the total mass of the quartz sand and the fluxing agent;

[0054] (3) Under an argon atmosphere, the mixture is placed in a high-temperature furnace and heated to 1700°C to melt and then kept at this temperature for 4 hours to form a eutectic;

[0055] (4) Under an argon atmosphere, the eutectic is slowly cooled to 898°C (SnO-SiO2 eutectic point) at a uniform speed and kept warm until the melt is completely solidified. It is then cooled to room temperature with the furnace to remove the impurity-containing flux slag SnO.

[0056] The purity of the purified quartz sand in this embodiment is 99.994%.

[0057] The above describes the specific embodiments of the present invention in detail, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

Claims

1. A method for purifying high-purity quartz sand, characterized in that: The specific steps are as follows: (1) Using acidic oxides B2O3 or SnO as fluxing agents, the addition amount of fluxing agents is determined according to the B2O3-SiO2 or SnO-SiO2 binary phase diagram. When the fluxing agent is B2O3, the addition amount is the composition range of B2O3 and SiO2 corresponding to the liquidus line at the SiO2-rich end of the B2O3-SiO2 phase diagram; when the fluxing agent is SnO, the addition amount is the composition range of SnO and SiO2 corresponding to the liquidus line at the SiO2-rich end of the SnO-SiO2 phase diagram. (2) crushing quartz sand into quartz sand powder by ball grinding, and uniformly mixing the quartz sand powder and fluxing slag to obtain a mixture; (3) In an inert gas atmosphere, the mixture is placed in a high-temperature furnace to heat and melt, and the temperature is maintained to form a eutectic; (4) Under an inert gas atmosphere, the eutectic is slowly cooled at a uniform speed to the eutectic point temperature of B2O3-SiO2 or SnO-SiO2 and kept warm until the melt is completely solidified, and then cooled to room temperature with the furnace to remove the fluxing slag containing impurities.

2. The method for purifying high-purity quartz sand according to claim 1, wherein: The addition amount of the flux slag agent is 10-90% of the total mass of the quartz sand and the flux slag agent.

3. The method for purifying high-purity quartz sand according to claim 1, wherein: The particle size of quartz sand powder is 150~400 mesh.

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