Production method of high-purity quartz sand and co-production of fluoroethylene carbonate

Abstract

The application discloses a production method of high-purity quartz sand and co-production of fluoroethylene carbonate, and comprises the following steps: S1. high-temperature calcination quenching; S2. ultrasonic acid immersion impurity removal; S3. high-temperature vacuum hydroxyl removal; S4. chlorination roasting, obtaining high-purity quartz sand; S5. reaction precipitation; S6. impurity detection and removal; S7. acid liquid supplement and reuse; S8. sodium fluoride solution preparation; S9. shunting; S10. fluorination reaction; S11. product refining, obtaining fluoroethylene carbonate. The application realizes production of high-purity quartz sand and co-production of fluoroethylene carbonate, and also realizes solid waste-free, liquid waste-free, gas waste-free, water resource recycling, waste heat gradient utilization, simple method and environmental protection, and can greatly improve the utilization efficiency of various resources.

Description

Technical Field

[0001] This invention relates to the field of purifying quartz sand and synthesizing fluoroethylene carbonate, specifically to a method for producing fluoroethylene carbonate from high-purity quartz sand. Background Technology

[0002] Quartz sand is a mineral containing silicon dioxide (SiO2) and is widely used in semiconductor manufacturing, glass industry, optical device manufacturing, and other fields. Its purification process primarily aims to obtain high-purity silicon dioxide to meet the requirements of various high-tech industries.

[0003] The process of producing high-purity quartz sand involves various technical requirements, from mining and raw material preparation to acid leaching, alkali leaching, washing, drying, grinding, and sorting. Impurities in quartz sand typically exist in the form of oxides, carbonates, and other metallic substances. Acid leaching is a common purification method that uses acids (usually hydrochloric or sulfuric acid) to dissolve these impurities, converting them into soluble salts while the quartz particles remain insoluble. After acid leaching, an alkaline solution (such as sodium hydroxide) may be used to neutralize the acidic residue and further remove residual impurities. During the purification process, repeated washing steps are used to rinse away any remaining acidic or alkaline substances, ensuring the purity of the final product. After purification, the quartz sand needs to be dried to remove moisture. This helps ensure the stability and purity of the final product.

[0004] In the field of electrochemistry, fluoroethylene carbonate exhibits numerous advantages, particularly in its important applications in high-power lithium-ion batteries. Fluoroethylene carbonate is commonly used as an electrolyte additive, improving battery performance, promoting the formation of a stable electrolyte / electrode interface film, and extending battery cycle life. Furthermore, fluoroethylene carbonate is widely used in advanced battery technologies, such as lithium-sulfur batteries, often in combination with other solvents and additives to enhance battery performance and safety. Currently, fluoroethylene carbonate can typically be prepared using four methods: direct fluorination, halogen exchange, transesterification, and electrochemical fluorination. These methods generally require large quantities of fluorinating agents, making their cost a significant portion of production costs. Reducing the cost of fluorinating agents during production is a major research direction in the preparation of fluoroethylene carbonate. Summary of the Invention

[0005] The purpose of this invention is to provide a production method for the co-production of fluoroethylene carbonate from high-purity quartz sand. This method achieves the production of fluoroethylene carbonate as a byproduct of high-purity quartz sand, while also achieving zero solid waste, zero liquid waste, zero gaseous waste, water resource recycling, and cascade utilization of waste heat. The method is simple and environmentally friendly, and can greatly improve the utilization efficiency of various resources.

[0006] To achieve the above objectives, the technical solution of the present invention is a method for producing high-purity quartz sand and co-producing fluoroethylene carbonate, comprising the following steps:

[0007] S1, High-temperature calcination and quenching: Quartz sand with a particle size of less than 100 mesh is transferred into a calcination furnace and calcined at a calcination temperature of 600-800℃ for 2-4 hours. After calcination, it is immediately quenched and cooled rapidly, filtered, and then transferred to a residual heat furnace for drying to obtain the preliminary calcined product.

[0008] S2, Ultrasonic acid leaching for impurity removal: The preliminary calcined product obtained in S1 is subjected to acid leaching for impurity removal under ultrasonic conditions, followed by deacidification and water washing, and then transferred to a waste heat furnace for drying. At the same time, quicklime is used to absorb the harmful gases generated to obtain acid-leached material. The acid leaching waste liquid and washing liquid are mixed and the mixture is transferred to S5.

[0009] S3, High-temperature vacuum dehydroxylation: The acid-leached material obtained in S2 is transferred into a high-temperature vacuum furnace and subjected to high-temperature vacuum dehydroxylation at a temperature of 1500-1600℃ for at least 3 hours to obtain a high-temperature material.

[0010] S4, Chlorination Roasting: The high-temperature material obtained in S3 is transferred to a high-temperature chlorination device, where chlorine gas is used as the chlorinating agent and high-temperature chlorination is carried out at a temperature of not less than 1600℃ for 1-2 hours. Finally, it is cooled to obtain high-purity quartz sand, and heat is supplied to the waste heat furnace during the cooling process.

[0011] S5, Reaction and Precipitation: Add a sodium fluoride solution with a mass concentration of 5% to 15% to the mixture obtained in S2, so that the molar ratio of sodium fluoride to fluorosilicic acid is 2:1. Mix and react until precipitation is complete, then filter and wash the precipitate to obtain the filtered solution and precipitate.

[0012] S6, Impurity Detection and Removal: Detects the iron and aluminum impurity particle content in the filtered solution of S5. When the iron and aluminum impurity ion concentration exceeds 10... -5 At a concentration of mol / L, impurity ions are removed to ensure that the concentration of impurity ions does not exceed 10. -5 mol / L, to obtain a purified solution;

[0013] S7, Acid replenishment and reuse: Detect the remaining amount of each acid in the impurity removal solution in S6, replenish each acid and transfer it to S2 for reuse in acid leaching and impurity removal;

[0014] S8, Sodium fluoride solution preparation: Add sodium hydroxide solution to the precipitate obtained in S5, mix and heat to 85-95℃ to react, ensuring that the pH value is not lower than 6.1 and not higher than 6.4 near the end of the reaction. After the reaction is completed, filter to obtain silica gel filter cake and sodium fluoride solution;

[0015] S9, splitting: a portion of the sodium fluoride solution obtained in S8 is refluxed to S5, and the remaining portion is mixed and stirred evenly with ball-milled silica powder at a weight ratio of 10 to 20:1. Then, it is evaporated and dried. During the evaporation and drying process, sodium fluoride adheres to the surface of the micro silica powder to obtain a sodium fluoride solid dispersion.

[0016] S10, Fluorination reaction: Sodium fluoride solid dispersion obtained in S9 and deacidified ethylene carbonate pretreatment are added to an organic solvent in a molar ratio of 1:1. The mixture is heated and mixed to react. After the reaction is completed, the mixture is filtered under reduced pressure and the filter cake is washed to obtain the crude product.

[0017] S11, Product Refining: The crude product obtained from S10 is purified by vacuum distillation to obtain fluoroethylene carbonate.

[0018] Furthermore, the ultrasound in S2 uses low-frequency 20kHz and high-frequency 40kHz ultrasound.

[0019] Furthermore, in S2, the acid leaching for impurity removal uses a mixed acid, specifically composed of hydrochloric acid, nitric acid, and hydrofluoric acid, wherein the concentration of hydrochloric acid is not less than 3 mol / L, the concentration of nitric acid is not less than 0.5 mol / L, and the concentration of hydrofluoric acid is not less than 0.5 mol / L; the treatment temperature for acid leaching for impurity removal is 50–70°C, and the acid leaching time is at least 5 hours.

[0020] Further, the specific steps of the deacidification and washing in S2 are as follows: first, add ultrapure water for deep immersion to remove impurities for 2-3 hours, then filter out the ultrapure water immersion solution, and then wash with ultrapure water 3-5 times.

[0021] Furthermore, in both S6 and S7, the detection uses a measuring electrode.

[0022] Further, in step S8, the silica gel filter cake is transferred into a reactor, heated and pressurized by steam, and stirred to obtain cryolite.

[0023] Furthermore, the water vapor is generated by evaporation and drying during the heating and mixing reaction of sodium fluoride solution in S10.

[0024] Furthermore, the ratio of the sodium fluoride solution refluxed to S5 in S9 to the sodium fluoride solution used to prepare the microsilica powder with sodium fluoride attached is 1:2.

[0025] Further, the organic solvent in S10 is one or a mixture of ethylene glycol diethyl ether, diethyl carbonate, and acetonitrile.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) This invention achieves zero-emission production of high-purity quartz sand and co-production of fluoroethylene carbonate by treating and recycling wastewater and solid waste. The production method is green and environmentally friendly.

[0028] (2) The present invention achieves relatively complete removal of deep impurities in quartz sand by sequentially ball milling and screening, high-temperature calcination and quenching, ultrasonic acid leaching to remove impurities, high-temperature vacuum dehydroxylation and chlorination roasting of crude quartz sand raw material, thereby obtaining high-quality high-purity quartz sand.

[0029] (3) This invention achieves water resource recycling by detecting and removing impurities in waste liquid and replenishing and reusing the liquid, thereby greatly reducing the waste of resources.

[0030] (4) By connecting the calcining furnace, the waste heat furnace and the high-temperature chlorination device, the present invention makes full use of heat in multiple stages, saves energy and ensures the continuous operation of the process.

[0031] Furthermore, the silica gel filter cake produced during the production of fluoroethylene carbonate is heated and pressurized by the water vapor generated during the evaporation and drying process of sodium fluoride solution, ultimately yielding cryolite. This improves the recycling and utilization of waste gas and solid waste, maximizes water resource utilization, and eliminates waste gas emissions. Detailed Implementation

[0032] To better illustrate the present invention, the following embodiments are provided for further explanation, but the scope of the present invention includes, but is not limited to, the following embodiments.

[0033] Example 1: A method for producing high-purity quartz sand and co-producing fluoroethylene carbonate, comprising the following steps:

[0034] The process of this invention will be illustrated using quartz sand produced in a certain area of ​​Shaanxi Province as an example:

[0035] After pretreatment, the main impurity contents of the quartz sand raw material are: Fe: 80ppm, Al: 30ppm.

[0036] S1, High-temperature calcination and quenching: The coarse quartz sand raw material is added to a ball mill for ball milling and screening to obtain quartz sand with a particle size of less than 100 mesh. The remaining raw material is further ball milled. The quartz sand with a particle size of less than 100 mesh is transferred to a calcination furnace and calcined at a calcination temperature of 700℃ for 2 hours. After calcination, it is immediately transferred to a water quenching tank for rapid cooling, filtered, and then transferred to a waste heat furnace for drying to obtain the preliminary calcined product.

[0037] S2, Ultrasonic acid leaching for impurity removal: The preliminary calcined product obtained in S1 is subjected to acid leaching for impurity removal for 6 hours under the assistance of ultrasonic waves at a low frequency of 20kHz and a high frequency of 40kHz and a treatment temperature of 60℃. Then, ultrapure water is added for deep leaching for impurity removal for 2.5 hours. The ultrapure water leaching solution is then filtered out, and the product is washed 4 times with ultrapure water. The product is then transferred to a waste heat furnace for drying. At the same time, quicklime is used to absorb the harmful gases generated to obtain the acid-leached material. The acid leaching waste liquid and the washing liquid are mixed and the mixture is transferred to S5.

[0038] It should be noted that the acid leaching for impurity removal uses a mixed acid, which is composed of hydrochloric acid, nitric acid and hydrofluoric acid, wherein the concentration of hydrochloric acid is not less than 3 mol / L, the concentration of nitric acid is not less than 0.5 mol / L and the concentration of hydrofluoric acid is not less than 0.5 mol / L.

[0039] S3, High-temperature vacuum dehydroxylation: The acid-leached material obtained in S2 is transferred into a high-temperature vacuum furnace and subjected to high-temperature vacuum dehydroxylation at 1500℃ for 4 hours to obtain a high-temperature material.

[0040] S4, Chlorination Roasting: The high-temperature material obtained from S3 is transferred to a high-temperature chlorination device, where chlorine gas is used as the chlorinating agent and high-temperature chlorination is carried out at 1600℃ for 1.5 hours. Finally, it is cooled to obtain high-purity quartz sand, and heat is supplied to the waste heat furnace during the cooling process.

[0041] S5, Reaction and Precipitation: Add a 10% sodium fluoride solution to the mixture obtained in S2, so that the molar ratio of sodium fluoride to fluorosilicic acid is 2:1. Mix and react until precipitation is complete. Then filter and wash the precipitate to obtain the filtered solution and precipitate.

[0042] S6, Impurity Detection and Removal: The content of iron and aluminum impurity particles in the filtered solution of S5 is detected using a measuring electrode. When the concentration of iron and aluminum impurity ions exceeds 10... -5 At a concentration of mol / L, impurity ions are removed to ensure that the concentration of impurity ions does not exceed 10. - 5 mol / L, to obtain a purified solution;

[0043] S7, Acid replenishment and reuse: The remaining amount of each acid in the impurity removal solution in S6 is detected by measuring electrodes. Hydrochloric acid, nitric acid and hydrofluoric acid are replenished and transferred to S3 for reuse in acid leaching and impurity removal.

[0044] It should be noted that after replenishment, the concentrations of each component meet the acid concentration requirements of S2;

[0045] S8, Sodium fluoride solution preparation: Add sodium hydroxide solution to the precipitate obtained in S5, mix and heat to 90℃ to react, ensuring that the pH value is not lower than 6.1 and not higher than 6.4 near the end of the reaction. After the reaction is completed, filter to obtain silica gel filter cake and sodium fluoride solution.

[0046] S9, splitting: a portion of the sodium fluoride solution obtained in S8 is refluxed to S5, and the remaining portion is mixed and stirred evenly with ball-milled silica powder at a weight ratio of 15:1. Then, it is evaporated and dried. During the evaporation and drying process, sodium fluoride adheres to the surface of the micro silica powder to obtain a sodium fluoride solid dispersion.

[0047] S10, Fluorination reaction: Sodium fluoride solid dispersion obtained in S9 and deacidified ethylene carbonate pretreatment ethylene carbonate are added to a mixed solvent of ethylene glycol diethyl ether and acetonitrile in a molar ratio of 1:1. The mixture is heated and reacted. After the reaction is completed, the mixture is filtered under reduced pressure and the filter cake is washed to obtain the crude product.

[0048] It should be noted that the silica gel filter cake in S8 is transferred into the reactor and heated and pressurized by passing water vapor generated during the evaporation and drying process in S10, and stirred to obtain cryolite.

[0049] S11, Product Refining: The crude product obtained from S10 is purified by vacuum distillation to obtain fluoroethylene carbonate.

[0050] The final high-purity quartz sand product obtained by testing has the following main impurity contents: Fe: 13ppm, Al: 11ppm.

[0051] The final fluoroethylene carbonate product was tested and found to have a yield of 92.3% and a purity of 99.9%.

[0052] Example 2: A method for producing high-purity quartz sand and co-producing fluoroethylene carbonate, comprising the following steps:

[0053] S1, High-temperature calcination and quenching: The coarse quartz sand raw material is added to a ball mill for ball milling and sieving to obtain quartz sand with a particle size of less than 100 mesh. The remaining raw material is further ball milled. The quartz sand with a particle size of less than 100 mesh is transferred to a calcination furnace and calcined at a calcination temperature of 800℃ for 3 hours. After calcination, it is immediately transferred to a water quenching tank for rapid cooling, filtered, and then transferred to a waste heat furnace for drying to obtain the preliminary calcined product.

[0054] S2, Ultrasonic acid leaching for impurity removal: The preliminary calcined product obtained in S1 is subjected to acid leaching for impurity removal for 5 hours under the assistance of ultrasonic waves at a low frequency of 20kHz and a high frequency of 40kHz and a treatment temperature of 50℃. Then, ultrapure water is added for deep leaching for impurity removal for 2 hours. The ultrapure water leaching solution is then filtered out, and the product is washed 4 times with ultrapure water. The product is then transferred to a waste heat furnace for drying. At the same time, quicklime is used to absorb the harmful gases generated to obtain the acid-leached material. The acid leaching waste liquid and washing liquid are mixed and the mixture is transferred to S5.

[0055] It should be noted that the acid leaching for impurity removal uses a mixed acid, which is composed of hydrochloric acid, nitric acid and hydrofluoric acid, wherein the concentration of hydrochloric acid is not less than 3 mol / L, the concentration of nitric acid is not less than 0.5 mol / L and the concentration of hydrofluoric acid is not less than 0.5 mol / L.

[0056] S3, High-temperature vacuum dehydroxylation: The acid-leached material obtained in S2 is transferred into a high-temperature vacuum furnace and subjected to high-temperature vacuum dehydroxylation at 1550℃ for 3 hours to obtain a high-temperature material.

[0057] S4, Chlorination Roasting: The high-temperature material obtained from S3 is transferred to a high-temperature chlorination device, where chlorine gas is used as the chlorinating agent and high-temperature chlorination is carried out at 1700℃ for 2 hours. Finally, it is cooled to obtain high-purity quartz sand, and heat is supplied to the waste heat furnace during the cooling process.

[0058] S5, Reaction and Precipitation: Add a 5% sodium fluoride solution to the mixture obtained in S2, so that the molar ratio of sodium fluoride to fluorosilicic acid is 2:1. Mix and react until precipitation is complete, then filter and wash the precipitate to obtain the filtered solution and precipitate.

[0059] S6, Impurity Detection and Removal: The content of iron and aluminum impurity particles in the filtered solution of S5 is detected using a measuring electrode. When the concentration of iron and aluminum impurity ions exceeds 10... -5 At a concentration of mol / L, impurity ions are removed to ensure that the concentration of impurity ions does not exceed 10. - 5 mol / L, to obtain a purified solution;

[0060] S7, Acid replenishment and reuse: The remaining amount of each acid in the impurity removal solution in S6 is detected by measuring electrodes. Hydrochloric acid, nitric acid and hydrofluoric acid are replenished and transferred to S2 for reuse in acid leaching and impurity removal.

[0061] It should be noted that after replenishment, the concentrations of each component meet the acid concentration requirements of S2;

[0062] S8, Sodium fluoride solution preparation: Add sodium hydroxide solution to the precipitate obtained in S5, mix and heat to 90℃ to react, ensuring that the pH value is not lower than 6.1 and not higher than 6.4 near the end of the reaction. After the reaction is completed, filter to obtain silica gel filter cake and sodium fluoride solution.

[0063] S9, splitting: a portion of the sodium fluoride solution obtained in S8 is refluxed to S5, and the remaining portion is mixed and stirred evenly with ball-milled silica powder at a weight ratio of 10:1. Then, it is evaporated and dried. During the evaporation and drying process, sodium fluoride adheres to the surface of the micro silica powder to obtain a sodium fluoride solid dispersion.

[0064] S10, Fluorination reaction: Sodium fluoride solid dispersion obtained in S9 and deacidified pretreated ethylene carbonate are added to ethylene glycol diethyl ether solvent in a molar ratio of 1:1. The mixture is heated and reacted. After the reaction is completed, the mixture is filtered under reduced pressure and the filter cake is washed to obtain the crude product.

[0065] It should be noted that the silica gel filter cake in S8 is transferred into the reactor and heated and pressurized by passing water vapor generated during the evaporation and drying process in S10, and stirred to obtain cryolite.

[0066] S11, Product Refining: The crude product obtained from S10 is purified by vacuum distillation to obtain fluoroethylene carbonate.

[0067] Example 3: A method for producing high-purity quartz sand and co-producing fluoroethylene carbonate, comprising the following steps:

[0068] S1, High-temperature calcination and quenching: The coarse quartz sand raw material is added to a ball mill for ball milling and sieving to obtain quartz sand with a particle size of less than 100 mesh. The remaining raw material is further ball milled. The quartz sand with a particle size of less than 100 mesh is transferred to a calcination furnace and calcined at a calcination temperature of 600℃ for 4 hours. After calcination, it is immediately transferred to a water quenching tank for rapid cooling, filtered, and then transferred to a waste heat furnace for drying to obtain the preliminary calcined product.

[0069] S2, Ultrasonic acid leaching for impurity removal: The preliminary calcined product obtained in S1 is subjected to acid leaching for impurity removal for 7 hours under the assistance of ultrasonic waves at a low frequency of 20kHz and a high frequency of 40kHz and a treatment temperature of 70℃. Then, ultrapure water is added for deep leaching for impurity removal for 3 hours. The ultrapure water leaching solution is then filtered out, and the product is washed three times with ultrapure water. The product is then transferred to a waste heat furnace for drying. At the same time, quicklime is used to absorb the harmful gases generated to obtain the acid-leached material. The acid leaching waste liquid and washing liquid are mixed, and the mixture is transferred to S5.

[0070] It should be noted that the acid leaching for impurity removal uses a mixed acid, which is composed of hydrochloric acid, nitric acid and hydrofluoric acid, wherein the concentration of hydrochloric acid is not less than 3 mol / L, the concentration of nitric acid is not less than 0.5 mol / L and the concentration of hydrofluoric acid is not less than 0.5 mol / L.

[0071] S3, High-temperature vacuum dehydroxylation: The acid-leached material obtained in S2 is transferred into a high-temperature vacuum furnace and subjected to high-temperature vacuum dehydroxylation at 1600℃ for 5 hours to obtain a high-temperature material.

[0072] S4, Chlorination Roasting: The high-temperature material obtained from S3 is transferred to a high-temperature chlorination device, where chlorine gas is used as the chlorinating agent and high-temperature chlorination is carried out at 1750℃ for 1.5 hours. Finally, it is cooled to obtain high-purity quartz sand, and heat is supplied to the waste heat furnace during the cooling process.

[0073] S5, Reaction and Precipitation: Add a 15% sodium fluoride solution to the mixture obtained in S2, so that the molar ratio of sodium fluoride to fluorosilicic acid is 2:1. Mix and react until precipitation is complete. Then filter and wash the precipitate to obtain the filtered solution and precipitate.

[0074] S6, Impurity Detection and Removal: The content of iron and aluminum impurity particles in the filtered solution of S5 is detected using a measuring electrode. When the concentration of iron and aluminum impurity ions exceeds 10... -5 At a concentration of mol / L, impurity ions are removed to ensure that the concentration of impurity ions does not exceed 10. - 5 mol / L, to obtain a purified solution;

[0075] S7, Acid replenishment and reuse: The remaining amount of each acid in the impurity removal solution in S6 is detected by measuring electrodes. Hydrochloric acid, nitric acid and hydrofluoric acid are replenished and transferred to S2 for reuse in acid leaching and impurity removal.

[0076] It should be noted that after replenishment, the concentrations of each component meet the acid concentration requirements of S2;

[0077] S8, Sodium fluoride solution preparation: Add sodium hydroxide solution to the precipitate obtained in S5, mix and heat to 85℃ to react, ensuring that the pH value is not lower than 6.1 and not higher than 6.4 near the end of the reaction. After the reaction is completed, filter to obtain silica gel filter cake and sodium fluoride solution.

[0078] S9, splitting: a portion of the sodium fluoride solution obtained in S8 is refluxed to S5, and the remaining portion is mixed and stirred evenly with ball-milled silica powder at a weight ratio of 20:1. Then, it is evaporated and dried. During the evaporation and drying process, sodium fluoride adheres to the surface of the micro silica powder to obtain a sodium fluoride solid dispersion.

[0079] S10, Fluorination reaction: Sodium fluoride solid dispersion obtained in S9 and deacidified ethylene carbonate pretreatment ethylene carbonate are added to diethyl carbonate solvent in a molar ratio of 1:1. The mixture is heated and reacted. After the reaction is completed, the mixture is filtered under reduced pressure and the filter cake is washed to obtain the crude product.

[0080] It should be noted that the silica gel filter cake in S8 is transferred into the reactor and heated and pressurized by passing water vapor generated during the evaporation and drying process in S10, and stirred to obtain cryolite.

[0081] S11, Product Refining: The crude product obtained from S10 is purified by vacuum distillation to obtain fluoroethylene carbonate.

[0082] Example 4: A method for producing high-purity quartz sand and co-producing fluoroethylene carbonate, comprising the following steps:

[0083] S1, High-temperature calcination and quenching: The coarse quartz sand raw material is added to a ball mill for ball milling and sieving to obtain quartz sand with a particle size of less than 100 mesh. The remaining raw material is further ball milled. The quartz sand with a particle size of less than 100 mesh is transferred to a calcination furnace and calcined at a calcination temperature of 650℃ for 2.5 hours. After calcination, it is immediately transferred to a water quenching tank for rapid cooling, filtered, and then transferred to a waste heat furnace for drying to obtain the preliminary calcined product.

[0084] S2, Ultrasonic acid leaching for impurity removal: The preliminary calcined product obtained in S1 is subjected to acid leaching for impurity removal for 8 hours under the assistance of ultrasonic waves at a low frequency of 20kHz and a high frequency of 40kHz and a treatment temperature of 55℃. Then, ultrapure water is added for deep leaching for impurity removal for 2.5 hours. The ultrapure water leaching solution is then filtered out, and the product is washed with ultrapure water 5 times. The product is then transferred to a waste heat furnace for drying. At the same time, quicklime is used to absorb the harmful gases generated to obtain the acid-leached material. The acid leaching waste liquid and washing liquid are mixed and the mixture is transferred to S5.

[0085] It should be noted that the acid leaching for impurity removal uses a mixed acid, which is composed of hydrochloric acid, nitric acid and hydrofluoric acid, wherein the concentration of hydrochloric acid is not less than 3 mol / L, the concentration of nitric acid is not less than 0.5 mol / L and the concentration of hydrofluoric acid is not less than 0.5 mol / L.

[0086] S3, High-temperature vacuum dehydroxylation: The acid-leached material obtained in S2 is transferred into a high-temperature vacuum furnace and subjected to high-temperature vacuum dehydroxylation at 1580℃ for 4 hours to obtain a high-temperature material.

[0087] S4, Chlorination Roasting: The high-temperature material obtained from S3 is transferred to a high-temperature chlorination device, where chlorine gas is used as the chlorinating agent and high-temperature chlorination is carried out at 1800℃ for 1 hour. Finally, it is cooled to obtain high-purity quartz sand, and heat is supplied to the waste heat furnace during the cooling process.

[0088] S5, Reaction and Precipitation: Add an 8% sodium fluoride solution to the mixture obtained in S2, so that the molar ratio of sodium fluoride to fluorosilicic acid is 2:1. Mix and react until precipitation is complete, then filter and wash the precipitate to obtain the filtered solution and precipitate.

[0089] S6, Impurity Detection and Removal: The content of iron and aluminum impurity particles in the filtered solution of S5 is detected using a measuring electrode. When the concentration of iron and aluminum impurity ions exceeds 10... -5 At a concentration of mol / L, impurity ions are removed to ensure that the concentration of impurity ions does not exceed 10. - 5 mol / L, to obtain a purified solution;

[0090] S7, Acid replenishment and reuse: The remaining amount of each acid in the impurity removal solution in S6 is detected by measuring electrodes. Hydrochloric acid, nitric acid and hydrofluoric acid are replenished and transferred to S2 for reuse in acid leaching and impurity removal.

[0091] It should be noted that after replenishment, the concentrations of each component meet the acid concentration requirements of S2;

[0092] S8, Sodium fluoride solution preparation: Add sodium hydroxide solution to the precipitate obtained in S5, mix and heat to 95℃ to react, ensuring that the pH value is not lower than 6.1 and not higher than 6.4 near the end of the reaction. After the reaction is completed, filter to obtain silica gel filter cake and sodium fluoride solution.

[0093] S9, splitting: a portion of the sodium fluoride solution obtained in S8 is refluxed to S5, and the remaining portion is mixed and stirred evenly with ball-milled silica powder at a weight ratio of 12:1. Then, it is evaporated and dried. During the evaporation and drying process, sodium fluoride adheres to the surface of the micro silica powder to obtain a sodium fluoride solid dispersion.

[0094] S10, Fluorination reaction: Sodium fluoride solid dispersion obtained in S9 and deacidified ethylene carbonate pretreatment ethylene carbonate are added to a mixed solvent of ethylene glycol diethyl ether, diethyl carbonate and acetonitrile in a molar ratio of 1:1. The mixture is heated and reacted. After the reaction is completed, the mixture is filtered under reduced pressure and the filter cake is washed to obtain the crude product.

[0095] It should be noted that the silica gel filter cake in S8 is transferred into the reactor and heated and pressurized by passing water vapor generated during the evaporation and drying process in S10, and stirred to obtain cryolite.

[0096] S11, Product Refining: The crude product obtained from S10 is purified by vacuum distillation to obtain fluoroethylene carbonate.

[0097] Example 5: A method for producing high-purity quartz sand and co-producing fluoroethylene carbonate, comprising the following steps:

[0098] S1, High-temperature calcination and quenching: The coarse quartz sand raw material is added to a ball mill for ball milling and sieving to obtain quartz sand with a particle size of less than 100 mesh. The remaining raw material is further ball milled. The quartz sand with a particle size of less than 100 mesh is transferred to a calcination furnace and calcined at a calcination temperature of 750℃ for 3.5 hours. After calcination, it is immediately transferred to a water quenching tank for rapid cooling, filtered, and then transferred to a waste heat furnace for drying to obtain the preliminary calcined product.

[0099] S2, Ultrasonic acid leaching for impurity removal: The preliminary calcined product obtained in S1 is subjected to acid leaching for impurity removal for 9 hours under the assistance of ultrasonic waves at a low frequency of 20kHz and a high frequency of 40kHz and a treatment temperature of 65℃. Then, ultrapure water is added for deep leaching for impurity removal for 2.5 hours. The ultrapure water leaching solution is then filtered out, and the product is washed 4 times with ultrapure water. The product is then transferred to a waste heat furnace for drying. At the same time, quicklime is used to absorb the harmful gases generated to obtain the acid-leached material. The acid leaching waste liquid and washing liquid are mixed and the mixture is transferred to S5.

[0100] It should be noted that the acid leaching for impurity removal uses a mixed acid, which is composed of hydrochloric acid, nitric acid and hydrofluoric acid, wherein the concentration of hydrochloric acid is not less than 3 mol / L, the concentration of nitric acid is not less than 0.5 mol / L and the concentration of hydrofluoric acid is not less than 0.5 mol / L.

[0101] S3, High-temperature vacuum dehydroxylation: The acid-leached material obtained in S2 is transferred into a high-temperature vacuum furnace and subjected to high-temperature vacuum dehydroxylation at 1520℃ for 6 hours to obtain a high-temperature material.

[0102] S4, Chlorination Roasting: The high-temperature material obtained from S3 is transferred to a high-temperature chlorination device, where chlorine gas is used as the chlorinating agent and high-temperature chlorination is carried out at 1650℃ for 1.5 hours. Finally, it is cooled to obtain high-purity quartz sand, and heat is supplied to the waste heat furnace during the cooling process.

[0103] S5, Reaction and Precipitation: Add a 13% sodium fluoride solution to the mixture obtained in S2, so that the molar ratio of sodium fluoride to fluorosilicic acid is 2:1. Mix and react until precipitation is complete. Then filter and wash the precipitate to obtain the filtered solution and precipitate.

[0104] S6, Impurity Detection and Removal: The content of iron and aluminum impurity particles in the filtered solution of S5 is detected using a measuring electrode. When the concentration of iron and aluminum impurity ions exceeds 10... -5 At a concentration of mol / L, impurity ions are removed to ensure that the concentration of impurity ions does not exceed 10. - 5 mol / L, to obtain a purified solution;

[0105] S7, Acid replenishment and reuse: The remaining amount of each acid in the impurity removal solution in S6 is detected by measuring electrodes. Hydrochloric acid, nitric acid and hydrofluoric acid are replenished and transferred to S2 for reuse in acid leaching and impurity removal.

[0106] It should be noted that after replenishment, the concentrations of each component meet the acid concentration requirements of S2;

[0107] S8, Sodium fluoride solution preparation: Add sodium hydroxide solution to the precipitate obtained in S5, mix and heat to 92℃ to react, ensuring that the pH value is not lower than 6.1 and not higher than 6.4 near the end of the reaction. After the reaction is completed, filter to obtain silica gel filter cake and sodium fluoride solution.

[0108] S9, splitting: a portion of the sodium fluoride solution obtained in S8 is refluxed to S5, and the remaining portion is mixed and stirred evenly with ball-milled silica powder at a weight ratio of 18:1. Then, it is evaporated and dried. During the evaporation and drying process, sodium fluoride adheres to the surface of the micro silica powder to obtain a sodium fluoride solid dispersion.

[0109] S10, Fluorination reaction: Sodium fluoride solid dispersion obtained in S9 and deacidified ethylene carbonate pretreatment ethylene carbonate are added to acetonitrile solvent in a molar ratio of 1:1. The mixture is heated and reacted. After the reaction is completed, the mixture is filtered under reduced pressure and the filter cake is washed to obtain the crude product.

[0110] It should be noted that the silica gel filter cake in S8 is transferred into the reactor and heated and pressurized by passing water vapor generated during the evaporation and drying process in S10, and stirred to obtain cryolite.

[0111] S11, Product Refining: The crude product obtained from S10 is purified by vacuum distillation to obtain fluoroethylene carbonate.

[0112] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for producing high-purity quartz sand and co-producing fluoroethylene carbonate, characterized in that, Includes the following steps: S1, High-temperature calcination and quenching: Quartz sand with a particle size of less than 100 mesh is transferred into a calcination furnace and calcined at a calcination temperature of 600-800℃ for 2-4 hours. After calcination, it is immediately quenched and cooled rapidly, filtered, and then transferred to a residual heat furnace for drying to obtain the preliminary calcined product. S2, Ultrasonic acid leaching for impurity removal: The preliminary calcined product obtained in S1 is subjected to acid leaching for impurity removal under ultrasonic conditions, followed by deacidification and water washing, and then transferred to a waste heat furnace for drying. At the same time, quicklime is used to absorb the harmful gases generated to obtain acid-leached material. The acid leaching waste liquid and washing liquid are mixed and the mixture is transferred to S5. Acid leaching for impurity removal uses mixed acid, which is specifically composed of hydrochloric acid, nitric acid and hydrofluoric acid. S3, High-temperature vacuum dehydroxylation: The acid-leached material obtained in S2 is transferred into a high-temperature vacuum furnace and subjected to high-temperature vacuum dehydroxylation at a temperature of 1500-1600℃ for at least 3 hours to obtain a high-temperature material. S4, Chlorination Roasting: The high-temperature material obtained in S3 is transferred to a high-temperature chlorination device, where chlorine gas is used as the chlorinating agent and high-temperature chlorination is carried out at a temperature of not less than 1600℃ for 1-2 hours. Finally, it is cooled to obtain high-purity quartz sand, and heat is supplied to the waste heat furnace during the cooling process. S5, Reaction and Precipitation: Add a sodium fluoride solution with a mass concentration of 5% to 15% to the mixture obtained in S2, so that the molar ratio of sodium fluoride to fluorosilicic acid is 2:

1. Mix and react until precipitation is complete, then filter and wash the precipitate to obtain the filtered solution and precipitate. S6, Impurity Detection and Removal: Detects the iron and aluminum impurity particle content in the filtered solution of S5. When the iron and aluminum impurity ion concentration exceeds... During this process, impurity ions are removed to ensure that the concentration of impurity ions does not exceed [a certain value]. The impurity-removed solution is obtained; S7, Acid replenishment and reuse: Detect the remaining amount of each acid in the impurity removal solution in S6, replenish each acid and transfer it to S2 for reuse in acid leaching and impurity removal; S8, Sodium fluoride solution preparation: Add sodium hydroxide solution to the precipitate obtained in S5, mix and heat to 85-95℃ to react, ensuring that the pH value is not lower than 6.1 and not higher than 6.4 near the end of the reaction. After the reaction is completed, filter to obtain silica gel filter cake and sodium fluoride solution. S9, splitting: a portion of the sodium fluoride solution obtained in S8 is refluxed to S5, and the remaining portion is mixed and stirred evenly with ball-milled silica powder at a weight ratio of 10 to 20:

1. Then, it is evaporated and dried. During the evaporation and drying process, sodium fluoride adheres to the surface of the micro silica powder to obtain a sodium fluoride solid dispersion. S10, Fluorination reaction: Sodium fluoride solid dispersion obtained in S9 and deacidified ethylene carbonate pretreatment are added to an organic solvent in a molar ratio of 1:

1. The mixture is heated and mixed to react. After the reaction is completed, the mixture is filtered under reduced pressure and the filter cake is washed to obtain the crude product. S11, Product Refining: The crude product obtained from S10 is purified by vacuum distillation to obtain fluoroethylene carbonate.

2. The production method of high-purity quartz sand co-producing fluoroethylene carbonate as described in claim 1, characterized in that: The ultrasound in S2 uses low-frequency 20kHz and high-frequency 40kHz ultrasound.

3. The production method of high-purity quartz sand co-producing fluoroethylene carbonate as described in claim 1, characterized in that: The mixed acid contains hydrochloric acid with a concentration of not less than 3 mol / L, nitric acid with a concentration of not less than 0.5 mol / L, and hydrofluoric acid with a concentration of not less than 0.5 mol / L; the acid leaching treatment temperature is 50–70°C, and the acid leaching time is at least 5 hours.

4. The production method of high-purity quartz sand co-producing fluoroethylene carbonate as described in claim 1, characterized in that: The specific steps for deacidification and washing in S2 are as follows: first, add ultrapure water for deep immersion to remove impurities for 2-3 hours, then filter out the ultrapure water immersion solution, and then wash with ultrapure water 3-5 times.

5. The production method of high-purity quartz sand co-producing fluoroethylene carbonate as described in claim 1, characterized in that: In both S6 and S7, the detection uses a measuring electrode.

6. The production method of high-purity quartz sand co-producing fluoroethylene carbonate as described in claim 1, characterized in that: In step S8, the silica gel filter cake is transferred into the reactor, where steam is introduced to heat and pressurize it, and the mixture is stirred to react and obtain cryolite.

7. The production method of high-purity quartz sand co-producing fluoroethylene carbonate as described in claim 6, characterized in that: The water vapor is generated by evaporation and drying during the heating and mixing reaction of sodium fluoride solution in S10.

8. The production method of high-purity quartz sand co-producing fluoroethylene carbonate as described in claim 1, characterized in that: The ratio of the sodium fluoride solution refluxed to S5 in S9 to the sodium fluoride solution used to prepare the microsilica powder with sodium fluoride attached is 1:

2.

9. The production method of high-purity quartz sand co-producing fluoroethylene carbonate as described in claim 1, characterized in that: The organic solvent in S10 is one or a mixture of ethylene glycol diethyl ether, diethyl carbonate, and acetonitrile.