Method for preparing high-purity quartz sand by combined microwave roasting

Abstract

This invention relates to a method for preparing high-purity quartz sand using a combination of microwave-ultrasound chlorination roasting and water bath mixed acid leaching. The method is characterized by removing inclusions within the quartz sand through microwave roasting, followed by chlorination roasting with the addition of a chlorinating agent. Ultrasonic vibration ensures thorough contact between the chlorinating agent and the ore particles, accelerating the desorption of chlorination products and converting metallic impurities into low-boiling-point metal chlorides, thereby achieving efficient separation of impurities from the quartz sand. Subsequent water bath acid leaching further effectively removes metallic impurities from the sand. The specific implementation process is as follows: First, the quartz sand undergoes microwave-ultrasound roasting, allowing the internal inclusions to preferentially absorb heat, creating a temperature difference. This generates a pressure difference between the inside and outside of the quartz sand, causing the inclusions to burst due to pressure and inducing external cracks in the quartz. Meanwhile, the ultrasound causes the material particles to vibrate and collide violently, breaking up particle agglomeration, increasing the specific surface area of ​​the particles, and allowing the microwave energy to act more evenly on each particle. Furthermore, a chlorinating agent is introduced during calcination to complete solid-gas separation, followed by water quenching and drying, then acid leaching with mixed acid, and finally drying to remove the remaining unvolatile impurities, ultimately obtaining a high-purity quartz sand product with a silicon content ≥99.96%.

Description

Technical Field

[0001] This invention relates to the field of rare earth pyrometallurgy-hydrometallurgy, specifically to a method for removing inclusions and metallic impurities from quartz sand by a microwave-ultrasound combined chlorination roasting reaction. Background Technology

[0002] High-purity quartz refers to a series of quartz products with a SiO2 purity greater than 99.9%. It is white in appearance and free of obvious impurities. Due to its excellent physicochemical properties such as high temperature resistance, corrosion resistance, low thermal expansion, high insulation, and light transmittance, it is widely used in high-tech industries such as fiber optic communication, solar photovoltaics, aerospace, electronics, and semiconductors, and holds a very important strategic position.

[0003] Currently, methods for preparing high-purity quartz sand include heat treatment, high-temperature vacuum methods, biological methods, and alkali treatment. Heat treatment involves high-temperature roasting, which causes a crystal transformation in quartz, accompanied by volume changes, generating internal stress and leading to cracks. This facilitates subsequent acid leaching. This process is low-cost and simple to operate, but the high-temperature heating consumes a lot of energy, and the lack of selectivity may result in poor removal of inclusions and impurities. High-temperature vacuum methods work similarly to heat treatment, but the high-temperature vacuum state is beneficial for removing hydroxyl groups from the quartz sand. Biological methods are relatively green and environmentally friendly, mainly using microorganisms to remove mineral impurities, but the microbial cultivation cycle is long. Alkali treatment converts insoluble valuable metals in quartz ore into soluble salts. The alkali solution commonly used is NaOH solution, which effectively removes Al, but also introduces impurities such as Na. In existing pyrometallurgical processes, the removal of inclusions and impurities mainly relies on microwave detonation technology. Traditional methods use high-temperature roasting, at temperatures above 1000℃, to cause inclusions to burst and move impurities to the quartz surface. However, this method has significant drawbacks: due to the lack of selective heating, the internal and external pressure difference is small, resulting in fewer inclusions bursting and making impurity removal difficult, leading to low product purity. More seriously, some chlorinating agents can introduce metallic impurities such as potassium and aluminum, causing contamination of the sand sample.

[0004] To address the aforementioned technical shortcomings, the innovation of this invention lies in constructing a selective separation system: microwave roasting selectively heats inclusions of impurities, thereby removing them; while the vibration energy generated by ultrasound provides additional activation energy for atoms and ions within the material, accelerating their diffusion and significantly promoting nucleation, sintering, and crystal transformation processes during roasting; and chlorination roasting converts existing impurities and those that have moved to the surface into low-boiling-point chlorides, achieving highly efficient separation of impurities from the sand sample. Simultaneously, controlled acid leaching conditions facilitate subsequent purification. This process overcomes the selective separation challenges of traditional impurity removal technologies, providing a new approach for preparing high-purity quartz sand.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of incomplete removal of inclusions, high purification cost, and introduction of other impurities in the process of preparing high-purity quartz sand, and to provide a method for preparing high-purity quartz sand.

[0007] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0008] A method for preparing high-purity quartz sand includes the following steps:

[0009] Quartz sand is mixed with chlorinating agent and additives and then subjected to microwave-ultrasonic combined calcination to obtain a mixture of solid chloride impurities and quartz sand. Low-boiling-point gaseous chlorides are discharged with the tail gas. The mixture is then quenched with water, washed and dried.

[0010] A mixed acid solution is added and heated in a water bath to leach the quartz sand, while impurities remain in the solution;

[0011] Finally, the quartz sand is washed and filtered with water, then dried to obtain the quartz sand product.

[0012] In the above-described method for preparing high-purity quartz sand, the chlorinating agent includes one or more of ammonium chloride, sodium chloride, and potassium chloride; the additives include one or more of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate; and the mixed acid is hydrofluoric acid / hydrochloric acid, hydrofluoric acid / sulfuric acid, or hydrofluoric acid / nitric acid.

[0013] This invention utilizes a combination of microwave and ultrasonic calcination with the addition of a chlorinating agent to quartz sand. Microwave heating allows for selective heating, facilitating the removal of inclusions and impurities. During high-temperature calcination, metallic impurities and the chlorinating agent form low-boiling-point chlorides that escape. Ultrasonic waves provide the kinetic conditions for the reaction, reducing the activation energy required for the reactants, thus decreasing energy consumption and lowering costs. The final acid leaching removes most of the remaining impurities, achieving separation. Taking ammonium chloride as an example, the impurities are alumina, iron oxide, and potassium oxide. The main chemical reactions occurring during the chlorination process are as follows:

[0014] Al2O3+2NH4Cl=2AlCl3↑+2NH3↑+H2O↑

[0015] 4Fe2O3+6NH4Cl=6Fe+2FeCl3+3N2↑+12H2O↑

[0016] K2O+2NH4Cl=2KCl+2NH3↑+H2O↑

[0017] In the above-described method for preparing high-purity quartz sand, preferably, the amount of solid chlorinating agent used is determined by the quartz sand content.

[0018] The amount of chlorinating agent should be 0.3 to 1 times the amount used in this invention. The amount of chlorinating agent used must be controlled within the preferred range of this invention. If too much chlorinating agent is used, it will increase production costs; if too little chlorinating agent is used, impurities will not be completely removed, and some impurities will still exist in the quartz, thereby reducing the purity of the quartz sand.

[0019] In the above-described method for preparing high-purity quartz sand, preferably, the microwave-ultrasonic combined calcination reaction temperature is 500℃~1000℃. The reaction temperature needs to be controlled within the preferred range of this invention. If the reaction temperature is too high, it will increase energy consumption; if the temperature is too low, it will lead to incomplete phase transformation of the quartz sand, resulting in fewer cracks in the quartz sand and impurities being unable to move from the interior to the quartz surface.

[0020] In the above-described method for preparing high-purity quartz sand, preferably, the microwave calcination reaction power is 1500W. The reaction power needs to be controlled within the preferred range of this invention. If the reaction power is too high, it will increase energy consumption; if the power is too low or the reaction time is too short, it will lead to incomplete heat absorption by the gas-liquid inclusions, resulting in a small internal and external pressure difference, making it difficult for the inclusions to rupture and resulting in a low impurity removal rate.

[0021] In the above-described method for preparing high-purity quartz sand, preferably, the ultrasonic calcination reaction frequency is 2×10⁻⁶. 4 ~10 9 The reaction frequency needs to be controlled within the preferred range of this invention. If the reaction power is too high, it will increase energy consumption; if the power is too low, it will cause incomplete vibration and collision of quartz sand particles, resulting in the microwaves not being able to act on all the quartz sand in time, making it difficult to break up inclusions and resulting in a low impurity removal rate.

[0022] In the above-described method for preparing high-purity quartz sand, preferably, the microwave-ultrasonic combined calcination reaction time is 1 h to 4 h. The reaction time needs to be controlled within the preferred range of this invention. If the reaction time is too long, it will increase energy consumption; if the reaction time is too short, it will lead to incomplete reaction.

[0023] In the above-described method for preparing high-purity quartz sand, preferably, the reaction temperature of the water bath heating is 60℃~90℃. The mixed acid is added and mixed with the quartz sand, while impurities dissolve and remain in the solution. The applicant has found through research that the reaction temperature during the water bath heating process needs to be controlled within the preferred range of this invention. If the reaction temperature is below 60℃, the acid leaching reaction is slow, incomplete, and impurities are difficult to remove; if the reaction temperature is above 90℃, it may lead to partial product loss and substandard product purity.

[0024] In the above-described method for preparing high-purity quartz sand, preferably, the chlorinating agent is used in a ratio of 1:0.3 to 1:1, and the additive is used in a ratio of 1:0.1 to 1:0.2. When mixing the chlorinating agent and additive with the quartz sand, the amounts of each component during the microwave calcination process must be controlled within the preferred range of this invention. If the amount is too low, the chlorination reaction will be incomplete, resulting in low impurity removal efficiency; if the amount is too high, excessive corrosive gases will be generated, significantly impacting the equipment, complicating the exhaust gas treatment process, and increasing costs.

[0025] In the above-described method for preparing high-purity quartz sand, preferably, the reaction time during water bath heating is 1 to 4 hours. The reaction time during water bath heating needs to be controlled within the preferred range of this invention. If the reaction time is less than 1 hour, the acid leaching reaction will be incomplete, and impurities will be difficult to remove; if the reaction time is more than 4 hours, it may lead to the loss of some product and the product purity will not meet the standards.

[0026] In the above-described method for preparing high-purity quartz sand, preferably, the main components and concentrations of the mixed acid include HF: 1 mol / L, H2SO4: 1 mol / L, HCl: 1 mol / L, and HNO3: 1 mol / L.

[0027] In the above-described method for preparing high-purity quartz sand, preferably, the ratio of the mixed acids is HF:H2SO4=1:9, HF:HCl=1:9, HF:HNO3=1:9, and the amount used is determined according to the amount of quartz sand used, i.e., the solid-liquid ratio is 1:2. The ratio and amount of mixed acids must be controlled within the preferred range of this invention. If the amount or ratio of mixed acids is too large, it will increase the use of acid solution and consume sand samples, increasing costs. If the amount or ratio is too small, the acid leaching reaction will be incomplete, impurities will be difficult to remove further, and it will be difficult to dissolve a small amount of quartz, thereby removing impurities.

[0028] This invention achieves efficient separation of quartz sand and impurity ions by limiting the amount of chlorinating agent, additives, microwave heating power, ultrasonic frequency, and mixed acid, and controlling the reaction temperature and time. This not only reduces energy consumption but also improves the purity of quartz sand, providing a foundation for the subsequent preparation of ultrapure quartz sand.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] (1) In view of the problems of high cost and low efficiency of the existing traditional method for preparing quartz sand, the present invention cleverly uses chlorinating agent to solve the problem of low impurity removal rate due to the calcination limit of quartz sand under the calcination process; the inclusions are heated and broken by the electromagnetic wave action of microwave heating, which can preferentially heat the inclusions and make the inclusions preferentially absorb heat. The ultrasonic vibration reduces the reaction activation energy and promotes the further reaction. The unvolatile chloride impurities can be dissolved in the subsequent acid leaching solution. After calcination and acid leaching, the silicon content of quartz sand can be increased from 96%-97% to more than 99.96%.

[0031] (2) The operation steps of this invention are simple and convenient, the process is short and easy to control, and it is suitable for industrial application. It overcomes the problems of large acid and alkali consumption, high roasting energy consumption, long process flow and poor selectivity of traditional roasting and alkali treatment methods. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention. For those skilled in the art, they can be understood without creative effort.

[0033] Under the premise of movement, other figures can be obtained from these figures.

[0034] Figure 1 This is a process flow diagram for preparing high-purity quartz sand according to the present invention. Detailed Implementation

[0035] To facilitate understanding of the present invention, the invention will be described more fully and in detail below with reference to preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0036] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0037] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0038] The chemical composition of the mixed acid solution processed in the following examples includes: HF 1mol / L, H2SO4 1mol / L, HCl 1mol / L, HNO3 1mol / L.

[0039] Example 1:

[0040] A method for preparing high-purity quartz sand according to the present invention is shown in the process flow diagram below. Figure 1 As shown, the specific steps include:

[0041] (1) Accurately weigh 200g of quartz sand, put it into a crucible, place the crucible in a muffle furnace for two calcinations and corresponding water quenching, then wash with water, and then filter to remove excess water. After filtration is completed, collect the filter paper and sand sample, transfer it to a PTFE beaker, and dry it for 12 hours.

[0042] (2) Accurately weigh 50g of the above-mentioned quartz sand and 20g of ammonium chloride. First, spread the ammonium chloride at the bottom of the ark, then pour in the quartz sand and completely cover the ammonium chloride.

[0043] (3) Place the ark in the baking oven, adjust the microwave power to 1500W, and the ultrasonic frequency to 2×10. 4 ~10 9 Between Hz, after the calcination temperature reaches 900℃ and is kept at that temperature for 1 hour, the sand sample is taken out and quenched in water. Then, it is washed with water multiple times, filtered to remove excess water, and after filtration is completed, the filter paper is collected to recover the quartz sand. Finally, it is dried for 12 hours.

[0044] (4) Finally, take 30g of the above-mentioned quartz sand and place it in a PTFE flask. Transfer the prepared mixed acid solution into the flask with a solid-liquid ratio of 1:2. Then place the flask in a water bath.

[0045] (5) In a water bath, at a constant temperature of 90°C, the acid leaching time was 4 hours. After the reaction, the solution was discarded, and then the quartz sand was washed with water. The quartz sand was washed with pure water 3-5 times, then filtered, and finally dried. After testing, the total impurity content in the quartz sand was less than or equal to 300 ppmw and the purity of the quartz sand reached 99.96% under the treatment of ammonium chloride as chlorinating agent, which provides raw materials for the further preparation of high-purity quartz sand.

[0046] Comparative Example 1:

[0047] The method for removing silicon from rare earth liquid through complexation in this comparative example comprises the following steps:

[0048] (1) Accurately weigh 200g of quartz sand, put it into a crucible, place the crucible in a muffle furnace for secondary roasting and corresponding water quenching, then wash with water, and then filter to remove excess water. After filtration is completed, collect the filter paper and sand sample, transfer it to a PTFE beaker, and dry it for 12 hours.

[0049] (2) Accurately weigh 50g of quartz sand and 20g of ammonium chloride. First, spread the ammonium chloride at the bottom of the ark, then pour in the quartz sand and completely cover the ammonium chloride.

[0050] (3) Place the ark in the baking oven, adjust the microwave power to 0W (change the microwave power) and turn off the microwave, then switch to normal heating, with an ultrasonic frequency of 2×10. 4 ~10 9 Between Hz, after the calcination temperature reaches 900℃ and is kept at that temperature for 1 hour, the sand sample is taken out and quenched in water, filtered to remove excess water, and after filtration, the filter paper is collected to recover the quartz sand, which is then dried for 12 hours.

[0051] (4) Finally, take 30g of the above-mentioned quartz sand and place it in a PTFE flask. Transfer the prepared mixed acid solution into the flask with a solid-liquid ratio of 1:2. Then place the flask in a water bath.

[0052] (5) In a water bath, at a constant temperature of 90°C, the acid leaching time is 4 hours. The solution after the reaction is taken out and filtered. During filtration, it is washed with pure water 3-5 times, then filtered by suction, and finally dried. After testing, it is found that the total impurity content in the quartz sand is less than or equal to 300 ppm when ammonium chloride is used as the chlorinating agent, and the purity of the quartz sand reaches 99.96%, which provides raw materials for the subsequent preparation of high-purity quartz sand.

[0053] Example 2:

[0054] A method for preparing high-purity quartz sand according to the present invention is shown in the process flow diagram below. Figure 1 As shown, the specific steps include:

[0055] (1) Accurately weigh 200g of quartz sand, put it into a crucible, place the crucible in a muffle furnace for two calcinations and corresponding water quenching, then wash with water, and then filter to remove excess water. After filtration is completed, collect the filter paper and sand sample, transfer it to a PTFE beaker, and dry it for 12 hours.

[0056] (2) Accurately weigh 50g of quartz sand and 20g of ammonium chloride. First, spread the ammonium chloride at the bottom of the ark, then pour in the quartz sand and completely cover the ammonium chloride.

[0057] (3) Place the ark in the roasting oven, adjust the microwave power to 1500W, and the ultrasonic frequency to 2×10. 4 ~10 9 Between Hz, after the calcination temperature reaches 900℃ and is kept at that temperature for 1 hour, the sand sample is taken out and quenched in water, filtered to remove excess water, and after filtration is completed, the filter paper is collected to recover the quartz sand, and then dried for 12 hours.

[0058] (4) Finally, take 30g of the above-mentioned quartz sand and place it in a PTFE flask. Transfer the prepared mixed acid solution into the flask with a solid-liquid ratio of 1:2. Then place the flask in a water bath.

[0059] (5) In a water bath, at a constant temperature of 90°C, the acid leaching time is 4 hours. The solution after the reaction is taken out and filtered. During filtration, it is washed with pure water 3-5 times, then filtered by suction, and finally dried. After testing, it is found that the total impurity content in the quartz sand is less than or equal to 300 ppmw and the purity of the quartz sand reaches 99.96% under the treatment of ammonium chloride as chlorinating agent, which provides raw materials for further preparation of high-purity quartz sand.

[0060] Comparative Example 2

[0061] The method for removing silicon from rare earth liquid through complexation in this comparative example comprises the following steps:

[0062] (1) Accurately weigh 200g of quartz sand, put it into a crucible, place the crucible in a muffle furnace for secondary roasting and corresponding water quenching, then wash with water, and then filter to remove excess water. After filtration is completed, collect the filter paper and sand sample, transfer it to a PTFE beaker, and dry it for 12 hours.

[0063] (2) Accurately weigh 50g of quartz sand and 20g of ammonium chloride. First, spread the ammonium chloride at the bottom of the ark, then pour in the quartz sand and completely cover the ammonium chloride.

[0064] (3) Place the ark in the roasting oven, adjust the microwave power to 1500W, and the ultrasonic frequency to 2×10. 4 ~10 9 Between Hz, when the calcination temperature reaches 500 (changing the calcination temperature) ℃, after holding at the temperature for 1 hour, the sand sample is taken out and quenched in water, then washed with water multiple times, then filtered to remove excess water. After filtration is completed, the filter paper is collected to recover the quartz sand, and finally dried for 12 hours.

[0065] (4) Finally, take 30g of the above-mentioned quartz sand and place it in a PTFE flask. Transfer the prepared mixed acid solution into the flask with a solid-liquid ratio of 1:2. Then place the flask in a water bath.

[0066] (5) In a water bath, at a constant temperature of 90°C, the acid leaching time is 4 hours. The solution after the reaction is taken out and filtered. During filtration, it is washed with pure water 3-5 times, then filtered by suction, and finally dried. After testing, it is found that the total impurity content in the quartz sand is less than or equal to 300 ppmw and the purity of the quartz sand reaches 99.96% under the treatment of ammonium chloride as chlorinating agent, which provides raw materials for further preparation of high-purity quartz sand.

[0067] Example 3:

[0068] A method for preparing high-purity quartz sand according to the present invention is shown in the process flow diagram below. Figure 1 As shown, the specific steps include:

[0069] (1) Accurately weigh 200g of quartz sand, put it into a crucible, place the crucible in a muffle furnace for two calcinations and corresponding water quenchings, then wash with water, and then filter to remove excess water. After filtration is complete, collect the filter media.

[0070] The paper and sand samples were transferred to a PTFE beaker and dried for 12 hours.

[0071] (2) Accurately weigh 50g of quartz sand and 20g of ammonium chloride. First, spread the ammonium chloride and additives into the bottom of the ark, then pour in the quartz sand and completely cover the ammonium chloride.

[0072] (3) Place the ark in the roasting oven, adjust the microwave power to 1500W, and the ultrasonic frequency to 2×10. 4 ~10 9 Between Hz, after the calcination temperature reaches 900℃ and is kept at that temperature for 1 hour, the sand sample is taken out and quenched in water, washed multiple times, then filtered to remove excess water. After filtration is completed, the filter paper is collected to recover the quartz sand, and finally dried for 12 hours.

[0073] (4) Finally, take 30g of the above-mentioned quartz sand and place it in a PTFE flask. Transfer the prepared mixed acid solution into the flask with a solid-liquid ratio of 1:2. Then place the flask in a water bath.

[0074] (5) In a water bath, at a constant temperature of 90°C, the acid leaching time is 4 hours. The solution after the reaction is taken out and filtered. During filtration, it is washed with pure water 3-5 times, then filtered by suction, and finally dried. After testing, it is found that the total impurity content in the quartz sand is less than or equal to 300 ppmw and the purity of the quartz sand reaches 99.96% under the treatment of ammonium chloride as chlorinating agent, which provides raw materials for further preparation of high-purity quartz sand.

[0075] Comparative Example 3:

[0076] The method for removing silicon from rare earth liquid through complexation in this comparative example comprises the following steps:

[0077] (1) Accurately weigh 200g of quartz sand, put it into a crucible, place the crucible in a muffle furnace for two calcinations and corresponding water quenching, then wash with water, and then filter to remove excess water. After filtration is completed, collect the filter paper and sand sample, transfer it to a PTFE beaker, and dry it for 12 hours.

[0078] (2) Accurately weigh 50g of quartz sand, 20g of ammonium chloride, and 5g of additive (use additive). First, spread the ammonium chloride and additive into the bottom of the ark, then pour in the quartz sand and completely cover the ammonium chloride.

[0079] (3) Place the ark in the roasting oven, adjust the microwave power to 1500W, and the ultrasonic frequency to 2×10. 4 ~10 9Between Hz, after the calcination temperature reaches 900℃ and is kept at that temperature for 1 hour, the sand sample is taken out and quenched in water, washed multiple times, then filtered to remove excess water. After filtration is completed, the filter paper is collected to recover the quartz sand, and finally dried for 12 hours.

[0080] (4) Finally, take 30g of the above-mentioned quartz sand and place it in a PTFE flask. Transfer the prepared mixed acid solution into the flask with a solid-liquid ratio of 1:2. Then place the flask in a water bath.

[0081] (5) In a water bath, at a constant temperature of 90°C, the acid leaching time was 4 hours. The solution after the reaction was taken out and filtered. During filtration, it was washed with pure water 3 times, then filtered by suction, and finally dried. After testing, it was found that the total impurity content in the quartz sand was less than or equal to 300 ppmw and the purity of the quartz sand reached 99.96% under the treatment of ammonium chloride as chlorinating agent, which provides raw materials for the subsequent preparation of high-purity quartz sand.

[0082] Example 4:

[0083] A method for preparing high-purity quartz sand according to the present invention is shown in the process flow diagram below. Figure 1 As shown, the specific steps include:

[0084] (1) Accurately weigh 200g of quartz sand, put it into a crucible, place the crucible in a muffle furnace for two calcinations and corresponding water quenching, then wash with water, and then filter to remove excess water. After filtration is completed, collect the filter paper and sand sample, transfer it to a PTFE beaker, and dry it for 12 hours.

[0085] (2) Accurately weigh 50g of quartz sand and 20g of ammonium chloride. First, spread the ammonium chloride at the bottom of the ark, then pour in the quartz sand and completely cover the ammonium chloride.

[0086] (3) Place the ark in the roasting oven, adjust the microwave power to 1500W, and the ultrasonic frequency to 2×10. 4 ~10 9 Between Hz, after the calcination temperature reaches 900℃ and is kept at that temperature for 1 hour, the sand sample is taken out and quenched in water, washed multiple times, then filtered to remove excess water. After filtration is completed, the filter paper is collected to recover the quartz sand, and finally dried for 12 hours.

[0087] (4) Finally, take 30g of the above-mentioned quartz sand and place it in a PTFE flask. Transfer the prepared mixed acid solution into the flask with a solid-liquid ratio of 1:2. Then place the flask in a water bath.

[0088] (5) In a water bath, at a constant temperature of 90°C, the acid leaching time is 4 hours. The solution after the reaction is taken out and filtered. During filtration, it is washed with pure water 3-5 times, then filtered by suction, and finally dried. After testing, it is found that the total impurity content in the quartz sand is less than or equal to 300 ppmw and the purity of the quartz sand reaches 99.96% under the treatment of ammonium chloride as chlorinating agent, which provides raw materials for further preparation of high-purity quartz sand.

[0089] Comparative Example 4:

[0090] The method for removing silicon from rare earth liquid through complexation in this comparative example comprises the following steps:

[0091] (1) Accurately weigh 200g of quartz sand, put it into a crucible, place the crucible in a muffle furnace for two calcinations and corresponding water quenching, then wash with water, and then filter to remove excess water. After filtration is completed, collect the filter paper and sand sample, transfer it to a PTFE beaker, and dry it for 12 hours.

[0092] (2) Accurately weigh 50g of quartz sand and 20g of ammonium chloride. First, spread the ammonium chloride at the bottom of the ark, then pour in the quartz sand and completely cover the ammonium chloride.

[0093] (3) Place the ark in the roasting oven, adjust the microwave power to 1500W, and the ultrasonic frequency to 2×10. 4 ~10 9 Between Hz, after the calcination temperature reaches 900℃ and is held for 2 hours (the holding time is varied), the sand sample is taken out and water-quenched, washed multiple times, and then filtered to remove excess water. After filtration is complete, the filtrate is collected.

[0094] Paper is recycled from quartz sand and then dried for 12 hours.

[0095] (4) Finally, take 30g of the above-mentioned quartz sand and place it in a PTFE flask. Transfer the prepared mixed acid solution into the flask with a solid-liquid ratio of 1:2. Then place the flask in a water bath.

[0096] (5) In a water bath, at a constant temperature of 90°C, the acid leaching time was 4 hours. The solution after the reaction was taken out and filtered. During filtration, it was washed with pure water 3 times, then filtered by suction, and finally dried. After testing, it was found that the total impurity content in the quartz sand was less than or equal to 300 ppmw and the purity of the quartz sand reached 99.96% under the treatment of ammonium chloride as chlorinating agent, which provides raw materials for the subsequent preparation of high-purity quartz sand.

[0097] Example 5:

[0098] A method for preparing high-purity quartz sand according to the present invention is shown in the process flow diagram below. Figure 1 As shown, the specific steps include:

[0099] (1) Accurately weigh 200g of quartz sand, put it into a crucible, place the crucible in a muffle furnace for two calcinations and corresponding water quenching, then wash with water, and then filter to remove excess water. After filtration is completed, collect the filter paper and sand sample, transfer it to a PTFE beaker, and dry it for 12 hours.

[0100] (2) Accurately weigh 50g of quartz sand and 20g of ammonium chloride. First, spread the ammonium chloride at the bottom of the ark, then pour in the quartz sand and completely cover the ammonium chloride.

[0101] (3) Place the ark in the roasting oven, adjust the microwave power to 1500W, and the ultrasonic frequency to 2×10. 4 ~10 9 Between Hz, after the calcination temperature reaches 900℃ and is kept at that temperature for 1 hour, the sand sample is taken out and quenched in water, washed multiple times, then filtered to remove excess water. After filtration is completed, the filter paper is collected to recover the quartz sand, and finally dried for 12 hours.

[0102] (4) Finally, take 30g of the above-mentioned quartz sand and place it in a tetrafluoro flask. Transfer the prepared mixed acid solution into the flask with a solid-liquid ratio of 1:2. Then place the flask in a water bath.

[0103] (5) In a water bath, at a constant temperature of 90°C, the acid leaching time is 4 hours. The solution after the reaction is taken out and filtered. During filtration, it is washed with pure water 3-5 times, then filtered by suction, and finally dried. After testing, it is found that the total impurity content in the quartz sand is less than or equal to 300 ppmw and the purity of the quartz sand reaches 99.96% under the treatment of ammonium chloride as chlorinating agent, which provides raw materials for further preparation of high-purity quartz sand.

[0104] Comparative Example 5:

[0105] The method for removing silicon from rare earth liquid through complexation in this comparative example comprises the following steps:

[0106] (1) Accurately weigh 200g of quartz sand, put it into a crucible, and place the crucible in a muffle furnace twice.

[0107] The sample was calcined and quenched in water, then washed with water and filtered to remove excess water. After filtration, the filter paper and sand sample were collected, transferred to a PTFE beaker, and dried for 12 hours.

[0108] (2) Accurately weigh 50g of quartz sand and 20g of ammonium chloride. First, spread the ammonium chloride at the bottom of the ark, then pour in the quartz sand and completely cover the ammonium chloride.

[0109] (3) Place the ark in the roasting oven, adjust the microwave power to 1500W, and the ultrasonic frequency to 2×10. 4 ~10 9Between Hz, after the calcination temperature reaches 900℃ and is kept at that temperature for 1 hour, the sand sample is taken out and quenched in water, washed multiple times, then filtered to remove excess water. After filtration is completed, the filter paper is collected to recover the quartz sand, and finally dried for 12 hours.

[0110] (4) Finally, take 30g of the above-mentioned quartz sand and place it in a PTFE flask. Transfer the prepared mixed acid solution into the flask with a solid-liquid ratio of 1:2. Then place the flask in a water bath.

[0111] (5) In a water bath, at a constant temperature of 90℃, the acid leaching time was 2h (the acid leaching time was changed), and the final pH was recorded. The solution after the reaction was taken out and filtered. During filtration, it was washed with pure water 3-5 times, then filtered by suction, and finally dried. After testing, it was found that the total impurity content in the quartz sand was less than or equal to 300ppmw and the purity of the quartz sand reached 99.96% under the treatment of ammonium chloride as chlorinating agent, which provides raw materials for the subsequent preparation of high-purity quartz sand.

[0112] Example 6:

[0113] A method for preparing high-purity quartz sand according to the present invention is shown in the process flow diagram below. Figure 1 As shown, the specific steps include:

[0114] (1) Accurately weigh 200g of quartz sand, put it into a crucible, place the crucible in a muffle furnace for two calcinations and corresponding water quenching, then wash with water, and then filter to remove excess water. After filtration is completed, collect the filter paper and sand sample, transfer it to a PTFE beaker, and dry it for 12 hours.

[0115] (2) Accurately weigh 50g of quartz sand and 20g of ammonium chloride. First, spread the ammonium chloride at the bottom of the ark, then pour in the quartz sand and completely cover the ammonium chloride.

[0116] (3) Place the ark in the roasting oven, adjust the microwave power to 1500W, and the ultrasonic frequency to 2×10. 4 ~10 9 Between Hz, after the calcination temperature reaches 900℃ and is held for 1 hour, the sand sample is taken out and water-quenched, and then washed multiple times. Then it is filtered to remove excess water. After filtration is completed, the filter paper is collected to recover the quartz sand, and finally it is dried for 12 hours.

[0117] (4) Finally, take 30g of the above-mentioned quartz sand and place it in a PTFE flask. Transfer the prepared mixed acid solution into the flask with a solid-liquid ratio of 1:2. Then place the flask in a water bath.

[0118] (5) In a water bath, at a constant temperature of 90°C, the acid leaching time is 4 hours. The solution after the reaction is taken out and filtered. During filtration, it is washed with pure water 3-5 times, then filtered by suction, and finally dried. After testing, it is found that the total impurity content in the quartz sand is less than or equal to 300 ppmw and the purity of the quartz sand reaches 99.96% under the treatment of ammonium chloride as chlorinating agent, which provides raw materials for further preparation of high-purity quartz sand.

[0119] Comparative Example 6:

[0120] The method for removing silicon from rare earth liquid through complexation in this comparative example comprises the following steps:

[0121] (1) Accurately weigh 200g of quartz sand, put it into a crucible, place the crucible in a muffle furnace for two calcinations and corresponding water quenching, then wash with water, and then filter to remove excess water. After filtration is completed, collect the filter paper and sand sample, transfer it to a PTFE beaker, and dry it for 12 hours.

[0122] (2) Accurately weigh 50g of quartz sand and 20g of ammonium chloride. First, spread the ammonium chloride at the bottom of the ark, then pour in the quartz sand and completely cover the ammonium chloride.

[0123] (3) Place the ark in the roasting oven, adjust the microwave power to 1500W, and the ultrasonic frequency to 2×10. 4 ~10 9 Between Hz, after the calcination temperature reaches 900℃ and is kept at that temperature for 1 hour, the sand sample is taken out and quenched in water, washed multiple times, then filtered to remove excess water. After filtration is completed, the filter paper is collected to recover the quartz sand, and finally dried for 12 hours.

[0124] (4) Finally, take 30g of the above-mentioned quartz sand and place it in a PTFE flask. Transfer the prepared mixed acid solution into the flask with a solid-liquid ratio of 1:2. Then place the flask in a water bath.

[0125] (5) In a water bath, at a constant temperature of 60℃ (changing the acid leaching temperature), the acid leaching time is 4h. The solution after the reaction is taken out and filtered. During filtration, it is washed with pure water 3-5 times, then filtered by suction, and finally dried. After testing, it is found that the total impurity content in the quartz sand is less than or equal to 300ppmw when ammonium chloride is used as the chlorinating agent, and the purity of the quartz sand reaches 99.96%, which provides raw materials for the subsequent preparation of high-purity quartz sand.

[0126] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing high-purity quartz sand by microwave-ultrasonic combined chlorination roasting-water bath mixed acid leaching, characterized in that, Includes the following steps: (1) First, the quartz sand is placed in a crucible and placed in a muffle furnace for two calcinations and corresponding water quenching, then leached with mixed acid in a water bath, and finally pretreated by washing and drying. (2) Quartz sand samples are mixed with chlorinating agent (selected from at least one of ammonium chloride, sodium chloride, and potassium chloride) and additive (at least one of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate) under microwave-ultrasonic heating conditions and then calcined. After water quenching, and after washing and drying, a stable quartz sand sample is formed. (3) Then, mixed acid is added to a water bath for acid leaching to separate impurities from the product. Quartz sand is obtained through solid-liquid separation, and then washed and dried to obtain high-purity quartz sand product.

2. The method of claim 1, wherein, In step (1), the two roasting processes are as follows: the first roasting temperature is 1000℃ and the holding temperature is 0.5h; the second roasting temperature is 650℃ and the holding temperature is 2h; after each roasting, the product must be water quenched and then washed and dried.

3. The method of claim 1, wherein the high purity quartz sand is prepared by the steps of: In step (1), the water bath acid immersion heating temperature is 90℃ and the holding time is 4h. ​ 4. The method of claim 1, wherein, The chlorinating agent mentioned in step (2) is at least one of ammonium chloride, sodium chloride, and potassium chloride. The dosage is expressed by different mass ratios of quartz sand sample to chloride, i.e., 1:0.3-1:

1.

5. The method according to claim 1, characterized in that, The additive mentioned in step (2) is at least one of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate. The amount added is expressed by different mass ratios of sample to additive, i.e., 1:0.1-1:0.

2.

6. The method for preparing high-purity quartz sand according to claim 1, characterized in that, In step (2), the microwave-ultrasonic calcination is carried out at a microwave power of 1500 W and an ultrasonic frequency of 2 x 10 4 ~10 9 Hz.

7. The method for preparing high-purity quartz sand according to claim 1, characterized in that, In step (2), the microwave-ultrasonic calcination reaction temperature is maintained in the range of 500-1000℃.

8. The method for preparing high-purity quartz sand according to claim 1, characterized in that, In step (2), the microwave-ultrasonic calcination reaction holding time is 1h-4h.

9. The method for preparing high-purity quartz sand according to claim 1, characterized in that, In step (3), the amount of mixed acid used is 2-5 times that of the solid, i.e., the solid-liquid ratio is 1:2-1:

5.

10. The method for preparing high-purity quartz sand according to claim 1, characterized in that, In step (3), the concentrations of the mixed acids are HF: 1 mol / L, HCl: 1 mol / L, H2SO4: 1 mol / L, and HNO3: 1 mol / L.

11. The method for preparing high-purity quartz sand according to claim 1, characterized in that, The acid leaching process in step (3) lasts for 1-4 hours.

12. The method for preparing high-purity quartz sand according to claim 1, characterized in that, The heating temperature for the acid leaching process in step (3) is 60-90℃.

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