Hydrogen fluoride preparation method, hydrogen fluoride, and battery material

Abstract

The present disclosure provides a hydrogen fluoride preparation method, hydrogen fluoride, and a battery material. The preparation method comprises the following steps: reacting a fluorosilicic acid solution with a sulfuric acid solution to obtain a mixed gas and a fluorine-containing sulfuric acid, wherein the content of hydrogen fluoride in the mixed gas is 10%-20%, and the content of hydrogen fluoride in the fluorine-containing sulfuric acid is 90%-80%; performing concentrated sulfuric acid treatment on the mixed gas to obtain sulfuric acid having absorbed the hydrogen fluoride; performing falling film evaporation treatment on the fluorine-containing sulfuric acid to obtain a hydrogen fluoride-containing gas phase; and washing the hydrogen fluoride-containing gas phase with the sulfuric acid having absorbed the hydrogen fluoride, to obtain hydrogen fluoride gas.

Description

Preparation methods of hydrogen fluoride, hydrogen fluoride and battery materials

[0001] Technical Field

[0002] This disclosure relates to the field of fluorochemical technology, specifically to a method for preparing hydrogen fluoride, hydrogen fluoride, and battery materials. Background Technology

[0003] Currently, the main processes for preparing anhydrous hydrogen fluoride are the fluorite method and the fluorosilicic acid method. The fluorite method uses the reaction of fluorite with sulfuric acid to produce anhydrous hydrogen fluoride. This is currently the mainstream process in the market, with mature technology, low investment, and high output, but high production costs and significant environmental impact. The fluorosilicic acid method is relatively mature and has better economic benefits.

[0004] Currently, the preparation of anhydrous hydrogen fluoride from fluorosilicic acid involves reacting 98% sulfuric acid with 40% fluorosilicic acid, but the overall yield of hydrogen fluoride is not high and needs further improvement.

[0005] Application content

[0006] This application aims to at least partially address one of the technical problems in the related art. Therefore, one objective of this application is to provide a method for preparing hydrogen fluoride, hydrogen fluoride, and battery materials. This method for preparing hydrogen fluoride facilitates improved hydrogen fluoride recovery rate.

[0007] The first aspect of this application discloses a method for preparing hydrogen fluoride. According to the embodiments of this application, the preparation method includes the following steps:

[0008] A fluorosilicic acid solution is reacted with a sulfuric acid solution to obtain a mixed gas and fluorinated sulfuric acid; the hydrogen fluoride content in the mixed gas is 10%~20%, and the hydrogen fluoride content in the fluorinated sulfuric acid is 90%~80%.

[0009] The mixed gas is treated with concentrated sulfuric acid to obtain absorbent sulfuric acid, which is the concentrated sulfuric acid after absorbing hydrogen fluoride;

[0010] Fluorine-containing sulfuric acid is subjected to falling film evaporation to obtain a hydrogen fluoride gas phase;

[0011] The hydrogen fluoride-containing gas phase is washed with sulfuric acid to obtain hydrogen fluoride gas.

[0012] In this embodiment, fluorosilicic acid reacts with sulfuric acid solution to obtain a gas phase (i.e., a mixed gas) and a liquid phase (i.e., fluorinated sulfuric acid). Both the gas phase and the liquid phase contain hydrogen fluoride. By controlling the content of hydrogen fluoride in the gas phase and the content of hydrogen fluoride in the liquid phase, the yield of hydrogen fluoride can be increased.

[0013] In this embodiment, the hydrogen fluoride content in the mixed gas is controlled at 10%~20%, which helps to ensure that the hydrogen fluoride in the mixed gas can be repeatedly absorbed when concentrated sulfuric acid is used to treat the mixed gas, thereby increasing the yield of hydrogen fluoride in the gas phase. The increased yield of hydrogen fluoride also helps to reduce the consumption of sulfuric acid. By controlling the hydrogen fluoride content in the fluorinated sulfuric acid to 90%~80%, the yield of hydrogen fluoride in the liquid phase can be increased through falling film evaporation, while avoiding excessive hydrogen fluoride content in the liquid phase, which would increase the consumption of sulfuric acid and the raw material and processing costs of sulfuric acid.

[0014] The second aspect of this application discloses a hydrogen fluoride obtained by the preparation method described above.

[0015] The third aspect of this application discloses a battery material comprising lithium hexafluorophosphate; the raw materials for preparing the battery material include the aforementioned hydrogen fluoride, or include the aforementioned hydrogen fluoride.

[0016] The fourth aspect of this application discloses a system for preparing hydrogen fluoride, comprising:

[0017] The decomposition tower is equipped with liquid phase inlets for fluorosilicic acid solution and sulfuric acid solution;

[0018] The absorption tower is equipped with a liquid phase inlet for concentrated sulfuric acid and a gas phase inlet connected to the gas phase outlet of the decomposition tower.

[0019] A falling film evaporator, the liquid phase inlet of which is connected to the liquid phase outlet of the decomposition tower;

[0020] The scrubbing tower has its gas phase inlet connected to the gas phase outlet of the falling film evaporator, and its liquid phase inlet connected to the liquid phase outlet of the absorption tower. The scrubbing tower also has a gas phase outlet for hydrogen fluoride gas.

[0021] The system provided in this application can be used to prepare the aforementioned hydrogen fluoride, which helps to improve the recovery rate of hydrogen fluoride.

[0022] In some embodiments of this application, the liquid phase output end of the scrubbing tower is connected to the liquid phase input end of the decomposition tower.

[0023] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0024] Figure 1 is a schematic diagram of a system for preparing hydrogen fluoride provided in some embodiments of this application.

[0025] Figure 2 is a schematic diagram of a system for preparing hydrogen fluoride provided in some embodiments of this application.

[0026] Figure 3 is a schematic diagram of the system for preparing hydrogen fluoride used in the specific embodiments of this application.

[0027] Figure 4 is a schematic diagram of the method flow for preparing hydrogen fluoride used in the specific embodiments of this application. Embodiments of the present invention

[0028] The embodiments of this application are described in detail below and are intended to explain this application, but should not be construed as limiting this application.

[0029] Currently, the main processes for producing anhydrous hydrogen fluoride are the fluorite method and the fluorosilicic acid method. The fluorite method uses the reaction of fluorite with sulfuric acid to produce anhydrous hydrogen fluoride. This is currently the mainstream process in the market, with mature technology and low investment, accounting for more than 80% of the total domestic output, but it has high production costs and significant environmental impact. The fluorosilicic acid method is relatively mature in technology and has better economic benefits.

[0030] Currently, the preparation of anhydrous hydrogen fluoride from fluorosilicic acid involves reacting 98% sulfuric acid with 40% fluorosilicic acid. Part of the hydrogen fluoride produced remains in the liquid phase for further extraction, while the other part escapes with silicon tetrafluoride gas, resulting in hydrogen fluoride loss. However, the overall yield of hydrogen fluoride is not high and needs further improvement.

[0031] Therefore, the first aspect of this application provides a method for preparing hydrogen fluoride, comprising:

[0032] A fluorosilicic acid solution is reacted with a sulfuric acid solution to obtain a mixed gas and fluorinated sulfuric acid; the hydrogen fluoride content in the mixed gas is 10%~20%, and the hydrogen fluoride content in the fluorinated sulfuric acid is 90%~80%.

[0033] The mixed gas is treated with concentrated sulfuric acid to obtain absorbent sulfuric acid, which is the concentrated sulfuric acid obtained after absorbing hydrogen fluoride;

[0034] Fluorine-containing sulfuric acid is subjected to falling film evaporation to obtain a hydrogen fluoride gas phase;

[0035] The hydrogen fluoride-containing gas phase is washed with sulfuric acid to obtain hydrogen fluoride gas.

[0036] In this embodiment, fluorosilicic acid reacts with sulfuric acid solution to obtain a gas phase (i.e., a mixed gas) and a liquid phase (i.e., fluorinated sulfuric acid). Both the gas phase and the liquid phase contain hydrogen fluoride. By controlling the content of hydrogen fluoride in the gas phase and the content of hydrogen fluoride in the liquid phase, the yield of hydrogen fluoride can be increased.

[0037] In this embodiment, the hydrogen fluoride content in the mixed gas is controlled at 10%~20%, which helps to ensure that the hydrogen fluoride in the mixed gas can be repeatedly absorbed when concentrated sulfuric acid is used to treat the mixed gas, thereby increasing the yield of hydrogen fluoride in the gas phase. The increased yield of hydrogen fluoride also helps to reduce the sulfuric acid consumption. By controlling the hydrogen fluoride content in the fluorinated sulfuric acid to 90%~80%, the yield of hydrogen fluoride in the liquid phase can be increased through falling film evaporation. In addition, it helps to avoid excessively high hydrogen fluoride content in the liquid phase, which would increase the sulfuric acid consumption and the raw material and processing costs of sulfuric acid. This is because the sulfuric acid consumption = sulfuric acid feed mass / anhydrous hydrogen fluoride product mass. Therefore, if too much hydrogen fluoride from the reaction of fluorosilicic acid solution and sulfuric acid solution dissolves in sulfuric acid, the falling film evaporator cannot completely precipitate the hydrogen fluoride, resulting in more fluorosilicic acid byproducts and a decrease in the yield of anhydrous hydrogen fluoride product. In order to increase the yield, the amount of sulfuric acid solution and fluorosilicic acid solution used will be further increased, leading to an increase in sulfuric acid consumption.

[0038] The sum of the hydrogen fluoride content in the mixed gas and the hydrogen fluoride content in the fluorinated sulfuric acid is 100%. For example, the hydrogen fluoride content in the mixed gas is 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, 16%, 16.5%, 17%, 17.5%, 18%, 18.5%, 19%, 19.5%, 20%, etc.; the corresponding hydrogen fluoride content in the fluorinated sulfuric acid is 90%, 89.5%, 89%, 88.5%, 88%, 87.5%, 87%, 86.5%, 86%, 85.5%, 85%, 84.5%, 84%, 83.5%, 83%, 82.5%, 82%, 81.5%, 81%, 80.5%, 80%, etc.

[0039] In this embodiment, fluorosilicic acid is reacted with sulfuric acid solution. The sulfuric acid solution acts as a catalyst to promote the decomposition of fluorosilicic acid to produce silicon tetrafluoride and hydrogen fluoride. The decomposition principle of fluorosilicic acid is: H2SiF6 = HF + SiF4.

[0040] The mixed gas is treated by absorption with concentrated sulfuric acid. Some of the hydrogen fluoride in the mixed gas dissolves in the concentrated sulfuric acid; some of the hydrogen fluoride reacts with the concentrated sulfuric acid to produce fluorosulfonic acid. The sulfuric acid obtained after absorption by concentrated sulfuric acid includes sulfuric acid, water, hydrogen fluoride and fluorosulfonic acid.

[0041] The concentrated sulfuric acid absorbs and then washes the hydrogen fluoride-containing gas phase. The sulfuric acid after absorption comes into contact with water and hydrogen fluoride gas. On one hand, the fluorosulfonic acid in the sulfuric acid after absorption hydrolyzes into hydrogen fluoride and sulfuric acid, releasing hydrogen fluoride gas. On the other hand, the sulfuric acid after absorption is diluted with water, releasing heat and releasing the dissolved hydrogen fluoride. Finally, the mixture of hydrogen fluoride in the hydrogen fluoride-containing gas phase, the hydrogen fluoride gas released from the hydrolysis of the sulfuric acid after absorption, and the dissolved hydrogen fluoride gas serves as the washed hydrogen fluoride gas, which can be further purified to obtain anhydrous hydrogen fluoride. The hydrolysis reaction mechanism of fluorosulfonic acid during the washing process is: HSO3F + H2O = H2SO4 + HF.

[0042] Furthermore, this embodiment employs a falling film evaporation method to evaporate sulfuric acid containing hydrogen fluoride. Under negative pressure, hydrogen fluoride is more volatile, significantly improving the evaporation and extraction efficiency and reducing sulfuric acid consumption. The overall temperature of falling film evaporation is also lower, which helps reduce steam loss. The hydrogen fluoride-containing gas phase evaporated from the falling film is directly washed with sulfuric acid after absorption by concentrated sulfuric acid. This gas phase typically carries moisture, promoting the release of hydrogen fluoride from the sulfuric acid after absorption by concentrated sulfuric acid. This facilitates the effective recovery of hydrogen fluoride produced in the main reaction (i.e., the reaction of fluorosilicic acid with sulfuric acid solution), increasing the hydrogen fluoride yield and further reducing sulfuric acid consumption.

[0043] In some embodiments of this application, the composition of the hydrogen fluoride gas phase is: sulfuric acid, 60%~70%; hydrogen fluoride, 3%~6%; and water, 25%~40%.

[0044] In some embodiments of this application, the hydrogen fluoride content in the mixed gas is 15% to 19%; the hydrogen fluoride content in the fluorinated sulfuric acid is 85% to 81%.

[0045] This application embodiment satisfies the above conditions by controlling the hydrogen fluoride content in the mixed gas and the hydrogen fluoride content in the fluorinated sulfuric acid, which helps to improve the overall yield of hydrogen fluoride and reduce the consumption of sulfuric acid. Further, the hydrogen fluoride content in the mixed gas is 16%~18%; the hydrogen fluoride content in the fluorinated sulfuric acid is 84%~82%.

[0046] In some embodiments of this application, the mass concentration C1 of fluorosilicic acid in the fluorosilicic acid solution is 18% to 55%, and the mass concentration of sulfuric acid in the sulfuric acid solution is 90% or more.

[0047] In the embodiments of this application, the mass concentrations of fluorosilicic acid and sulfuric acid solution satisfy the above conditions, which enables the decomposition reaction of fluorosilicic acid and sulfuric acid solution.

[0048] As an example, the mass concentration of fluorosilicic acid in the fluorosilicic acid solution is 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, etc.

[0049] As an example, the mass concentration of sulfuric acid in the sulfuric acid solution is 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, etc.

[0050] Furthermore, the mass concentration of fluorosilicic acid in the fluorosilicic acid solution is 50%~55%, and the mass concentration of sulfuric acid in the sulfuric acid solution is above 98%.

[0051] This application embodiment limits the mass concentration of the fluorosilicic acid solution to 50%~55%, which helps to reduce the amount of sulfuric acid used and lower the overall sulfuric acid consumption. This is because during the reaction between the fluorosilicic acid solution and the sulfuric acid solution, the sulfuric acid absorbs water to promote the decomposition reaction. If a higher concentration of fluorosilicic acid solution is used, its water content is relatively low, the amount of sulfuric acid absorbed is less, and the amount of sulfuric acid used is also reduced, which helps to reduce the amount of sulfuric acid used and lower the overall sulfuric acid consumption.

[0052] In addition, increasing the concentration of the sulfuric acid solution and reducing its water content helps to reduce the production of dilute sulfuric acid as a byproduct.

[0053] Furthermore, the mixed gas also includes silicon tetrafluoride. In this embodiment, the source of the fluorosilicic acid solution includes the fluorosilicic acid solution generated from the treatment of silicon tetrafluoride, thus recycling the resource.

[0054] Furthermore, in the embodiments of this application, the source of the sulfuric acid solution includes washed sulfuric acid obtained by absorbing sulfuric acid from the hydrogen fluoride gas phase.

[0055] In some embodiments of this application, the mass ratio of fluorosilicic acid solution to sulfuric acid solution in the reaction of fluorosilicic acid solution and sulfuric acid solution is 1:1 to 1:4.

[0056] In this embodiment, by controlling the mass ratio of fluorosilicic acid to sulfuric acid solution in the main reaction, it is beneficial to regulate the hydrogen fluoride content in the mixed gas and the hydrogen fluoride content in the fluorinated sulfuric acid to meet the specified conditions, thereby improving the hydrogen fluoride yield and reducing the sulfuric acid consumption.

[0057] For example, the mass ratio of fluorosilicic acid solution to sulfuric acid solution is 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9, 1:3, 1:3.1, 1:3.2, 1:3.3, 1:3.4, 1:3.5, 1:3.6, 1:3.7, 1:3.8, 1:3.9, 1:4, etc.

[0058] In some embodiments of this application, the reaction of fluorosilicic acid solution with sulfuric acid solution satisfies one of the following:

[0059] (i) The mass concentration of fluorosilicic acid in the fluorosilicic acid solution satisfies 18%≤C1<30%, and the mass ratio of fluorosilicic acid solution to sulfuric acid solution is 1:2~1:4;

[0060] (ii) The mass concentration of fluorosilicic acid in the fluorosilicic acid solution satisfies 30%≤C1<40%, and the mass ratio of fluorosilicic acid solution to sulfuric acid solution is 1:2~1:3;

[0061] (iii) The mass concentration of fluorosilicic acid in the fluorosilicic acid solution meets the requirement of 40%≤C1≤55%, and the mass ratio of fluorosilicic acid solution to sulfuric acid solution is 1:1~1:2.

[0062] In this embodiment, the mass concentration of fluorosilicic acid in the fluorosilicic acid solution satisfies 18%≤C1<30%, and the mass ratio of fluorosilicic acid solution to sulfuric acid solution is 1:2~1:4. More than 90% of the hydrogen fluoride produced in the reaction is soluble in sulfuric acid solution, and less than 10% of the hydrogen fluoride enters the gas phase and is output as a mixed gas, which is absorbed by concentrated sulfuric acid. The absorption amount of concentrated sulfuric acid is relatively low, and it will continue to absorb hydrogen fluoride during the subsequent washing process. Therefore, the yield of hydrogen fluoride is improved, but there is still considerable room for improvement.

[0063] In this embodiment, the mass concentration of fluorosilicic acid in the fluorosilicic acid solution satisfies 30%≤C1<40%, and the mass ratio of fluorosilicic acid solution to sulfuric acid solution is 1:2~1:3. 10%~13% of the hydrogen fluoride produced in the reaction enters the gas phase, and the amount absorbed by concentrated sulfuric acid is relatively increased, but it is not yet saturated. A small amount of hydrogen fluoride can still be absorbed during the washing process, and the hydrogen fluoride yield will be further improved.

[0064] In this embodiment, the mass concentration of fluorosilicic acid in the fluorosilicic acid solution satisfies 40%≤C1≤55%, and the mass ratio of fluorosilicic acid solution to sulfuric acid solution is 1:1~1:2. 10%~20% of the hydrogen fluoride produced in the reaction enters the gas phase, and the amount absorbed by concentrated sulfuric acid increases, reaching near saturation or saturation. After washing, a large amount of hydrogen fluoride can be released, promoting a better improvement in the hydrogen fluoride yield.

[0065] In some embodiments of this application, the process of absorbing sulfuric acid to wash the hydrogen fluoride-containing gas phase further includes obtaining recovered sulfuric acid; the recovered sulfuric acid satisfies at least one of the following:

[0066] (a) Recover sulfuric acid as a source of sulfuric acid solution and react it with fluorosilicic acid solution;

[0067] (b) The recovered sulfuric acid components, calculated as a percentage by mass, consist of 91% to 95% sulfuric acid and 1% to 5% hydrogen fluoride.

[0068] In some embodiments of this application, the reaction temperature is controlled at 80 ℃ to 120 ℃ during the reaction of fluorosilicic acid solution and sulfuric acid solution.

[0069] In this embodiment, a lower reaction temperature is advantageous for increasing the hydrogen fluoride content in the fluorinated sulfuric acid and decreasing the hydrogen fluoride content in the mixed gas. By controlling the reaction temperature of the fluorosilicic acid solution and the sulfuric acid solution to 80℃~120℃, it is beneficial to regulate the hydrogen fluoride content in the mixed gas and the hydrogen fluoride content in the fluorinated sulfuric acid to meet the specified conditions. As an example, the reaction temperature is controlled at 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, etc.

[0070] In some embodiments of this application, the reaction temperature is controlled at 80 ℃ to 100 ℃ during the reaction of fluorosilicic acid solution and sulfuric acid solution.

[0071] In this embodiment, by controlling the reaction temperature of the fluorosilicic acid solution and the sulfuric acid solution to remain within a low temperature range, it is beneficial to control the hydrogen fluoride content in the mixed gas and the hydrogen fluoride content in the fluorinated sulfuric acid to meet the specified conditions, thereby reducing energy consumption. As an example, the reaction temperature is controlled at 80 ℃, 82 ℃, 84 ℃, 86 ℃, 88 ℃, 90 ℃, 92 ℃, 94 ℃, 96 ℃, 98 ℃, 100 ℃, etc.

[0072] In some embodiments of this application, the preparation method further includes:

[0073] Hydrogen fluoride gas is condensed to obtain crude anhydrous hydrogen fluoride.

[0074] The crude anhydrous hydrogen fluoride is subjected to distillation and degassing processes to obtain the finished anhydrous hydrogen fluoride.

[0075] In this embodiment, the washed hydrogen fluoride gas is condensed to obtain crude anhydrous hydrogen fluoride; the crude anhydrous hydrogen fluoride is then subjected to distillation and degassing to obtain the finished anhydrous hydrogen fluoride, i.e., the target product, anhydrous hydrogen fluoride.

[0076] In some embodiments of this application, fluorinated sulfuric acid is subjected to falling film evaporation to obtain a liquid phase containing hydrogen fluoride;

[0077] The liquid phase containing hydrogen fluoride is stripped with air to obtain a mixture of dilute sulfuric acid and stripping gas;

[0078] Hydrofluoric acid is obtained by treating the stripped gas mixture with water absorption.

[0079] In this embodiment, hot air is used to strip the hydrogen fluoride-containing liquid phase, which reduces steam loss and the generation of sulfuric acid as a byproduct. Stripping yields dilute sulfuric acid and a stripping mixture; the hot air and hydrogen fluoride are absorbed by water to produce hydrofluoric acid, thus yielding two byproducts. Furthermore, the stripping mixture contains hot air, carrying a high amount of heat into the water absorption device, which helps reduce the heating energy consumption of the water absorption device and improves resource utilization.

[0080] In some embodiments of this application, the mixed gas also includes silicon tetrafluoride, and the mixed gas is further treated with concentrated sulfuric acid to obtain silicon tetrafluoride gas after being absorbed by concentrated sulfuric acid; the silicon tetrafluoride gas after being absorbed by concentrated sulfuric acid is subjected to fluorosilicic acid absorption treatment, filtration treatment, and washing treatment to obtain by-product silicon dioxide.

[0081] In some embodiments of this application, a first fluorosilicic acid solution is used to absorb silicon tetrafluoride gas absorbed by concentrated sulfuric acid to obtain a silicon fluoroacic acid solution containing silicon dioxide.

[0082] A silica-containing fluorosilicic acid solution was filtered to obtain a second fluorosilicic acid solution and a silica-containing solid phase.

[0083] The silica-containing solid phase was washed to obtain a tertiary fluorosilicic acid solution and silica byproducts.

[0084] In this embodiment, a first fluorosilicic acid solution is used to absorb silicon tetrafluoride gas absorbed by concentrated sulfuric acid. The fluorosilicic acid provides an acidic environment, promoting the hydrolysis reaction of silicon tetrafluoride as follows: SiF4 + H2O = H2SiF6 + SiO2, thereby obtaining a silica-containing fluorosilicic acid solution. Compared to the first fluorosilicic acid solution, the mass concentration of fluorosilicic acid in the silica-containing fluorosilicic acid solution is increased. Therefore, this absorption process serves two purposes: firstly, to obtain silica as a byproduct, and secondly, to concentrate the fluorosilicic acid.

[0085] In this embodiment, a silica-containing fluorosilicic acid solution is filtered to obtain a second fluorosilicic acid solution and a silica-containing solid phase. Through filtration, solid-liquid separation is achieved, and silica is further extracted. At the same time, a concentrated second fluorosilicic acid solution is obtained, and the mass concentration of the second fluorosilicic acid solution is greater than that of the first fluorosilicic acid solution.

[0086] In this embodiment of the application, impurities in the silicon dioxide solid phase are further removed by washing to obtain silicon dioxide byproducts with high purity, while a trifluorosilicic acid solution with low mass concentration is obtained.

[0087] In some embodiments of this application, as shown in FIG1, the preparation method of hydrogen fluoride includes the following steps:

[0088] S1000. Fluorosilicic acid is decomposed with sulfuric acid solution to produce a mixed gas and sulfuric acid containing hydrogen fluoride; the mixed gas includes silicon tetrafluoride and hydrogen fluoride. The hydrogen fluoride content in the mixed gas is 10%~20%, and the hydrogen fluoride content in the fluorinated sulfuric acid is 90%~80%.

[0089] S2000. Concentrated sulfuric acid is used to absorb hydrogen fluoride in a mixed gas to obtain sulfuric acid and silicon tetrafluoride gas after absorption by concentrated sulfuric acid.

[0090] S3000. Sulfuric acid containing hydrogen fluoride is treated by falling film evaporation to produce a liquid phase and a gas phase containing hydrogen fluoride.

[0091] S6000. The hydrogen fluoride gas phase is washed with sulfuric acid after absorption by concentrated sulfuric acid to obtain washed hydrogen fluoride gas and washed sulfuric acid.

[0092] S4000. The washed hydrogen fluoride gas is condensed to obtain crude anhydrous hydrogen fluoride; the crude anhydrous hydrogen fluoride is then distilled and degassed to obtain finished anhydrous hydrogen fluoride.

[0093] S5000. The liquid phase containing hydrogen fluoride is stripped with air to obtain dilute sulfuric acid and stripping gas as byproducts; the stripping gas includes air and stripped hydrogen fluoride; the stripping gas is then treated with water absorption to obtain hydrofluoric acid as a byproduct.

[0094] Furthermore, it also includes the following steps:

[0095] A silicon fluoride gas absorbed by concentrated sulfuric acid is absorbed by a first fluorosilicic acid solution to obtain a silicon dioxide-containing fluorosilicic acid solution.

[0096] The fluorosilicic acid solution containing silica was filtered to obtain a second fluorosilicic acid solution and a silica-containing solid phase.

[0097] The silica-containing solid phase is washed and dried to obtain byproduct silica.

[0098] In some embodiments of this application, as shown in FIG2, the method for preparing hydrogen fluoride includes the following steps:

[0099] S1000. Fluorosilicic acid is decomposed with sulfuric acid solution to produce a mixed gas and sulfuric acid containing hydrogen fluoride; the mixed gas includes silicon tetrafluoride and hydrogen fluoride. The hydrogen fluoride content in the mixed gas is 10%~20%, and the hydrogen fluoride content in the fluorinated sulfuric acid is 90%~80%.

[0100] S2000. Concentrated sulfuric acid is used to absorb hydrogen fluoride in a mixed gas to obtain sulfuric acid and silicon tetrafluoride gas after absorption by concentrated sulfuric acid.

[0101] S3000. The silicon tetrafluoride gas absorbed by concentrated sulfuric acid is absorbed by a first fluorosilicic acid solution to obtain a fluorosilicic acid solution containing silicon dioxide;

[0102] S4000. The silica-containing fluorosilicic acid solution is filtered to obtain a second fluorosilicic acid solution and a silica-containing solid phase. The filtered second fluorosilicic acid solution is recycled back to step S1000 as fluorosilicic acid or as a raw material for fluorosilicic acid, and undergoes a decomposition reaction with sulfuric acid solution. The silica-containing solid phase is washed, and the resulting solid phase is dried to obtain byproduct silica. The liquid phase obtained from washing is the third fluorosilicic acid solution, which is used as a raw material for the first fluorosilicic acid solution.

[0103] S5000. Sulfuric acid containing hydrogen fluoride is treated by falling film evaporation to produce a liquid phase and a gas phase containing hydrogen fluoride.

[0104] S6000. The hydrogen fluoride gas phase is washed with sulfuric acid after absorption by concentrated sulfuric acid to obtain washed hydrogen fluoride gas and washed sulfuric acid. The washed sulfuric acid is recycled back to step S1000 as a sulfuric acid solution or as a raw material for the sulfuric acid solution to undergo a decomposition reaction with fluorosilicic acid.

[0105] S7000. The washed hydrogen fluoride gas is condensed to obtain crude anhydrous hydrogen fluoride; the crude anhydrous hydrogen fluoride is then distilled and degassed to obtain finished anhydrous hydrogen fluoride.

[0106] S8000. The liquid phase containing hydrogen fluoride is stripped by air to obtain dilute sulfuric acid and stripping mixed gas as byproducts; the stripping mixed gas includes air and stripped hydrogen fluoride; the stripping mixed gas is treated by water absorption to obtain hydrofluoric acid as a byproduct.

[0107] In some embodiments of this application, as shown in FIG3, the method for preparing hydrogen fluoride includes the following steps:

[0108] S1000. Fluorosilicic acid with a mass concentration of 18%~55% and sulfuric acid with a mass concentration of 90%~98% are introduced into a decomposition tower, with the mass ratio of fluorosilicic acid to sulfuric acid being 1:1~1:4. The reaction takes place in the decomposition tower, producing a mixed gas including silicon tetrafluoride gas and hydrogen fluoride gas, and sulfuric acid containing hydrogen fluoride. The decomposition reaction taking place in the decomposition tower is shown below:

[0109] H2SiF6 = HF + SiF4.

[0110] Reaction temperature: 80 ℃~120 ℃, preferably 80 ℃~100 ℃.

[0111] The composition of sulfuric acid in the self-washing tower is: sulfuric acid, 91%~95%; hydrogen fluoride, 1%~5%; water, 2%~6%.

[0112] Composition of sulfuric acid containing hydrogen fluoride: sulfuric acid, 60%~70%; hydrogen fluoride, 3%~6%; water, 25%~40%.

[0113] S2000. The silicon tetrafluoride gas and hydrogen fluoride gas generated in step S1000 are passed through a sulfuric acid absorption tower. The mixture of silicon tetrafluoride and hydrogen fluoride is absorbed by 98% sulfuric acid, and the hydrogen fluoride gas is absorbed into the 98% sulfuric acid. At the same time, the 98% sulfuric acid cools the mixture.

[0114] The composition of sulfuric acid after absorption in the sulfuric acid absorption tower: sulfuric acid, 94%~96%; hydrogen fluoride, 1%~3%; water: 2%~4%.

[0115] Temperature of sulfuric acid absorption tower: 20 ℃~80 ℃.

[0116] S3000. The silicon tetrafluoride gas absorbed in the absorption tower in step S2000 is introduced into the silicon tetrafluoride absorption tower, where 25%~30% fluorosilicic acid is used to absorb the silicon tetrafluoride gas, forming a fluorosilicic acid solution containing silicon dioxide. The hydrolysis reaction carried out in the silicon tetrafluoride absorption tower is as follows:

[0117] SiF4 + H2O = H2SiF6 + SiO2.

[0118] Then, the silica-containing fluorosilicic acid solution is filtered, and the resulting fluorosilicic acid solution enters a 40%–55% fluorosilicic acid storage tank and returns to the decomposition tower for step S1000. The filtered silica is washed, and the resulting solid phase and washing liquid are separated. The solid phase is dried to obtain byproduct silica, which is sold as a byproduct. The washing liquid enters an 11%–18% fluorosilicic acid solution storage tank, and the 11%–18% fluorosilicic acid is vacuum concentrated to a concentration of 25%–30% before entering the silicon tetrafluoride absorption tower.

[0119] The concentration of fluorosilicic acid in the washing solution is 3%~10%.

[0120] Temperature of the silicon tetrafluoride absorption tower: 20 ℃~50 ℃.

[0121] S4000. The sulfuric acid containing hydrogen fluoride produced in step S1000 enters a falling film evaporator for heating and evaporation, producing gaseous hydrogen fluoride and liquid dilute sulfuric acid.

[0122] Falling film evaporator temperature: 130 ℃~170 ℃; pressure: -3 kpa~0 kpa.

[0123] Composition of gaseous hydrogen fluoride: hydrogen fluoride, 80%~99%; water, 1%~20%.

[0124] Composition of liquid dilute sulfuric acid: sulfuric acid, 60%~70%; hydrogen fluoride, 0%~1%; water, 30%~40%.

[0125] S5000. The gaseous hydrogen fluoride (containing sulfuric acid and water) generated in step S4000 enters the scrubbing tower and is washed with sulfuric acid absorbed by the sulfuric acid absorption tower in step 2. The hydrogen fluoride in the sulfuric acid absorbed by the sulfuric acid absorption tower is released.

[0126] The temperature of the scrubbing tower is 80 ℃~140 ℃, and the pressure is -3 kpa~0 kpa.

[0127] The composition of the washing solution after washing: sulfuric acid, 91%~95%; hydrogen fluoride, 1%~5%; water, 2%~6%.

[0128] S6000. The washed hydrogen fluoride gas obtained in step S3000 enters the condenser and is condensed into anhydrous crude hydrogen fluoride (i.e., crude AHF).

[0129] Composition of crude anhydrous hydrogen fluoride: hydrogen fluoride, 97%~99%; sulfuric acid, 0%~1%; water, 0~1%.

[0130] Condenser temperature: 5 ℃~18 ℃.

[0131] S7000. Crude anhydrous hydrogen fluoride is fed into a distillation column for distillation, and then into a degassing column to obtain pure hydrogen fluoride, which is the finished anhydrous hydrogen fluoride product (i.e., finished product AHF). The liquid in the distillation column bottoms is returned to the washing process.

[0132] Anhydrous hydrogen fluoride product purity: ≥99.97%, hydrogen fluoride yield: 80%~90%.

[0133] The composition of the liquid in the bottom of the distillation column is: hydrogen fluoride, 90%~95%; sulfuric acid, 1%~5%; and water, 0%~1%.

[0134] Distillation column bottom temperature: 21 ℃~28 ℃, distillation column top temperature: 17 ℃~19.5 ℃.

[0135] The temperature at the bottom of the degassing tower is 19.5 ℃~21 ℃, and the temperature at the top of the degassing tower is 17 ℃~19.5 ℃.

[0136] S8000. The liquid dilute sulfuric acid produced in step S4000 enters a stripping tower and is stripped using hot air to remove hydrogen fluoride from the liquid dilute sulfuric acid. The hydrogen fluoride and hot air then enter an absorption tower to obtain hydrofluoric acid as a byproduct. After stripping, the sulfuric acid is cooled to obtain 60%~70% dilute sulfuric acid.

[0137] Temperature of the stripping tower: 100 ℃~140 ℃.

[0138] Temperature of the absorption tower: 20 ℃~40 ℃.

[0139] The second aspect of this application provides a hydrogen fluoride, which is prepared by the above-described preparation method or includes the above-described hydrogen fluoride.

[0140] The hydrogen fluoride provided in this application embodiment is obtained by the above preparation method, which has low energy consumption and high hydrogen fluoride yield.

[0141] A third aspect of this application provides a battery material, including lithium hexafluorophosphate; the raw materials for preparing the battery material include the aforementioned hydrogen fluoride.

[0142] A third aspect of this application provides a system for preparing hydrogen fluoride, comprising:

[0143] The decomposition tower is equipped with liquid phase inlets for fluorosilicic acid solution and sulfuric acid solution;

[0144] The absorption tower is equipped with a liquid phase inlet for concentrated sulfuric acid and a gas phase inlet connected to the gas phase outlet of the decomposition tower.

[0145] A falling film evaporator, the liquid phase inlet of which is connected to the liquid phase outlet of the decomposition tower;

[0146] The washing tower has a gas phase input end connected to the gas phase output end of the falling film evaporator, and a liquid phase input end connected to the liquid phase output end of the absorption tower. The washing tower is also equipped with a gas phase output end for hydrogen fluoride gas.

[0147] The preparation system provided in this application embodiment can be used to prepare the above-mentioned hydrogen fluoride, or to prepare hydrogen fluoride using the above-mentioned preparation method.

[0148] In some embodiments of this application, the liquid phase outlet of the scrubbing tower is connected to the liquid phase inlet of the fluorosilicic acid solution and sulfuric acid solution in the decomposition tower. This facilitates the recovery and reuse of sulfuric acid.

[0149] The present application will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present application in any way. The reagents used in the embodiments are all from Aladdin Biochemical Technology Co., Ltd.

[0150] Example 1

[0151] Step 1: 55% fluorosilicic acid and 98% sulfuric acid are introduced into the decomposition tower, with a mass ratio of 1:2. The reaction takes place in the decomposition tower to produce a mixed gas including silicon tetrafluoride gas and hydrogen fluoride gas, and sulfuric acid containing hydrogen fluoride.

[0152] The reaction temperature is 100 ℃.

[0153] The composition of a sulfuric acid solution containing hydrogen fluoride is: 66% sulfuric acid, 4% hydrogen fluoride, and 30% water.

[0154] Step 2: Use concentrated sulfuric acid to absorb the mixed gas entering the sulfuric acid absorption tower; part of the hydrogen fluoride dissolves in the concentrated sulfuric acid, and part of the hydrogen fluoride reacts with the concentrated sulfuric acid to produce fluorosulfonic acid, resulting in fluorinated sulfuric acid and silicon tetrafluoride gas.

[0155] The temperature of the sulfuric acid absorption tower is below 80℃.

[0156] Concentration of concentrated sulfuric acid: 98%

[0157] Fluorosulfuric acid composition: 93% sulfuric acid, 2% hydrogen fluoride, 3% fluorosulfonic acid, and 2% water.

[0158] Step 3: Take 500 g of sulfuric acid solution containing hydrogen fluoride and add it to 1000 ml of PFA (perfluoroalkoxyethylene ether copolymer) analytical vessel. After analytical treatment, the gas phase is obtained.

[0159] The analysis temperature was 140 ℃ and the pressure was -10 kPa.

[0160] The gas phase composition is: 95% sulfuric acid, 1% hydrogen fluoride, and 4% water.

[0161] Step 4: Use 150 g of fluorinated sulfuric acid to wash the gas phase entering the washing tower; fluorosulfonic acid reacts with water to produce sulfuric acid and hydrogen fluoride, and the hydrogen fluoride in the fluorinated sulfuric acid is released to obtain the washed sulfuric acid solution and hydrogen fluoride gas.

[0162] The reaction mechanism of fluorosulfonic acid with water to produce sulfuric acid and hydrogen fluoride is: HSO3F + H2O = H2SO4 + HF.

[0163] Scrubber tower temperature: 50 ℃.

[0164] Scrubber gas phase temperature: 80 ℃~140 ℃

[0165] The composition of the sulfuric acid solution after washing is: 91% sulfuric acid, 2% hydrogen fluoride, 3% fluorosulfonic acid, and 4% water.

[0166] Step 5: The hydrogen fluoride gas from the scrubbing tower in step 4 is condensed in a condenser, distilled in a distillation tower, and degassed in a degassing tower to obtain anhydrous hydrogen fluoride.

[0167] Condenser temperature: 50 ℃.

[0168] Distillation column temperature: 23 ℃.

[0169] Degassing tower temperature: 21 ℃.

[0170] Examples 2-26

[0171] The specific preparation methods of hydrogen fluoride provided in Examples 2-26 are as shown in Example 1, and the specific parameter values ​​are shown in Table 1.

[0172] Table 1

[0173]

[0174] Performance testing

[0175] I. Testing Method:

[0176] 1. Determination of hydrogen fluoride yield: According to national standard GB / T 7746-2023; the calculation formula is as follows:

[0177] Yield of hydrogen fluoride: ,in:

[0178] m(AHF) represents the weight of the product's anhydrous hydrogen fluoride, in grams;

[0179] m(H2SiF6) represents the weight of fluorosilicic acid reacted with the first sulfuric acid, in grams;

[0180] w(H2SiF6) represents the mass fraction of fluorosilicic acid that reacts with the first sulfuric acid.

[0181] "2" represents the molar ratio of fluorosilicic acid to hydrogen fluoride; "20" represents the molar mass of HF; "144" represents the molar mass of H2SiF6.

[0182] 2. Sulfuric acid consumption: Consumption (H2SO4) = m(H2SO4) / m(anhydrous hydrogen fluoride), dimensionless; where:

[0183] m(H2SO4) represents the total weight of sulfuric acid added during the preparation process, in grams;

[0184] m (anhydrous hydrogen fluoride) indicates the weight of the product's anhydrous hydrogen fluoride, in grams.

[0185] II. Test Results:

[0186] Performance tests were conducted on Examples 1-26, and the results are shown in Table 2.

[0187] Table 2

[0188]

[0189] Performance test results analysis and explanation:

[0190] 1. As shown in Examples 16-22, the mass concentration of fluorosilicic acid in the fluorosilicic acid solution satisfies 18%≤C1<30%, and the mass ratio of fluorosilicic acid solution to sulfuric acid solution is 1:2~1:4. Most of the hydrogen fluoride produced in the reaction dissolves in the sulfuric acid solution, and only a small amount (less than 10%) of hydrogen fluoride enters the gas phase and is output as a mixed gas, which is absorbed by concentrated sulfuric acid. The absorption amount of concentrated sulfuric acid is relatively low, and it will continue to absorb hydrogen fluoride during the subsequent washing process. Therefore, the yield of hydrogen fluoride is improved, but there is still a lot of room for improvement.

[0191] (1) Specifically, the yield of hydrogen fluoride and the consumption of sulfuric acid were investigated under the same mass concentration of fluorosilicic acid and different mass ratios of fluorosilicic acid solution and sulfuric acid solution. As shown in Examples 16-20, taking the mass concentration of fluorosilicic acid in the fluorosilicic acid solution satisfying C1=20% as an example: ① As the mass ratio of fluorosilicic acid solution to sulfuric acid solution decreased and the amount of sulfuric acid solution increased, the content of hydrogen fluoride in the liquid phase showed an increasing trend, while the content of hydrogen fluoride in the gas phase showed a decreasing trend. The yield of hydrogen fluoride showed a gradual decreasing trend. The hydrogen fluoride preparation method provided in Example 9 (i.e., the mass ratio of fluorosilicic acid solution to sulfuric acid solution was 1:2) obtained a higher yield of hydrogen fluoride. This is because when the mass ratio of fluorosilicic acid solution to sulfuric acid solution is greater than 1:2 (i.e., the ratio is lower than 1:2), more sulfuric acid is used, the boiling point of the system increases, and at the same temperature, the amount of hydrogen fluoride that can be evaporated from the liquid phase decreases, which leads to a decreasing trend in the yield of hydrogen fluoride. ② As the mass ratio of fluorosilicic acid solution to sulfuric acid solution decreases and the amount of sulfuric acid solution used increases, the consumption of sulfuric acid per unit shows an increasing trend.

[0192] (2) Specifically, the yield of hydrogen fluoride and the consumption of sulfuric acid were investigated under the same mass ratio of fluorosilicic acid solution and sulfuric acid solution, and under different mass concentrations of fluorosilicic acid. As shown in Examples 16 and 21-22, taking a mass ratio of fluorosilicic acid solution to sulfuric acid solution of 1:2 as an example: ① As the mass concentration of fluorosilicic acid increases, the content of hydrogen fluoride in the liquid phase shows a decreasing trend, while the content of hydrogen fluoride in the gas phase shows an increasing trend, and the yield of hydrogen fluoride shows an increasing trend. ② As the mass concentration of fluorosilicic acid increases, the consumption of sulfuric acid shows a decreasing trend.

[0193] 2. As shown in Examples 9-15, the mass concentration of fluorosilicic acid in the fluorosilicic acid solution satisfies 30%≤C1<40%, and the mass ratio of fluorosilicic acid solution to sulfuric acid solution is 1:2~1:3. A large amount of hydrogen fluoride produced in the reaction enters the gas phase, and the amount absorbed by concentrated sulfuric acid is relatively increased, but it is not yet saturated. A small amount of hydrogen fluoride can still be absorbed during the washing process, and the yield of hydrogen fluoride will be further improved.

[0194] (1) Specifically, the yield of hydrogen fluoride and the consumption of sulfuric acid were investigated under the same mass concentration of fluorosilicic acid and different mass ratios of fluorosilicic acid solution and sulfuric acid solution. As shown in Examples 9-13, taking the mass concentration of fluorosilicic acid in the fluorosilicic acid solution satisfying C1=35% as an example: ① As the mass ratio of fluorosilicic acid solution to sulfuric acid solution decreased and the amount of sulfuric acid solution increased, the content of hydrogen fluoride in the liquid phase showed an increasing trend, while the content of hydrogen fluoride in the gas phase showed a decreasing trend. The yield of hydrogen fluoride showed a gradual decreasing trend. The hydrogen fluoride preparation method provided in Example 9 (i.e., the mass ratio of fluorosilicic acid solution to sulfuric acid solution is 1:2) obtained a higher yield of hydrogen fluoride. This is because when the mass ratio of fluorosilicic acid solution to sulfuric acid solution is greater than 1:2 (i.e., the ratio is lower than 1:2), more sulfuric acid is used, the boiling point of the system increases, and at the same temperature, the amount of hydrogen fluoride that can be evaporated from the liquid phase decreases, which leads to a decreasing trend in the yield of hydrogen fluoride. ② As the mass ratio of fluorosilicic acid solution to sulfuric acid solution decreases and the amount of sulfuric acid solution used increases, the consumption of sulfuric acid per unit shows an increasing trend.

[0195] (2) Specifically, the yield of hydrogen fluoride and the consumption of sulfuric acid were investigated under the same mass ratio of fluorosilicic acid solution and sulfuric acid solution, and under different mass concentrations of fluorosilicic acid. As shown in Examples 9 and 14-15, taking a mass ratio of fluorosilicic acid solution to sulfuric acid solution of 1:2 as an example: ① As the mass concentration of fluorosilicic acid increases, the content of hydrogen fluoride in the liquid phase shows a decreasing trend, while the content of hydrogen fluoride in the gas phase shows an increasing trend, and the yield of hydrogen fluoride shows an increasing trend. ② As the mass concentration of fluorosilicic acid increases, the consumption of sulfuric acid shows a decreasing trend.

[0196] 3. As shown in Examples 1-8, the mass concentration of fluorosilicic acid in the fluorosilicic acid solution meets the requirement of 40%≤C1≤55%, and the mass ratio of fluorosilicic acid solution to sulfuric acid solution is 1:1~1:2. More hydrogen fluoride produced by the reaction enters the gas phase, and the amount absorbed by concentrated sulfuric acid increases, which can reach or approach saturation. After entering the washing process, a large amount of hydrogen fluoride can be released, which promotes a better improvement in the yield of hydrogen fluoride.

[0197] (1) Specifically, the yield of hydrogen fluoride and the consumption of sulfuric acid were investigated under the same mass concentration of fluorosilicic acid and different mass ratios of fluorosilicic acid solution and sulfuric acid solution. As shown in Examples 1-6, taking the mass concentration of fluorosilicic acid in the fluorosilicic acid solution satisfying C1=55% as an example: ① As the mass ratio of fluorosilicic acid solution to sulfuric acid solution decreased and the amount of sulfuric acid solution increased, the content of hydrogen fluoride in the liquid phase showed an increasing trend, while the content of hydrogen fluoride in the gas phase showed a decreasing trend. The yield of hydrogen fluoride showed a trend of first increasing and then decreasing. The hydrogen fluoride preparation method provided in Example 3 (i.e., the mass ratio of fluorosilicic acid solution to sulfuric acid solution was 1:1.2) obtained a higher yield of hydrogen fluoride. This is because when the mass ratio of fluorosilicic acid solution to sulfuric acid solution is greater than 1:1.2 (i.e., the ratio is lower than the 1:1.2 ratio), more sulfuric acid is used, the boiling point of the system increases, and at the same temperature, the amount of hydrogen fluoride that can be evaporated from the liquid phase decreases, which leads to a decreasing trend in the yield of hydrogen fluoride. ② As the mass ratio of fluorosilicic acid solution to sulfuric acid solution decreases and the amount of sulfuric acid solution used increases, the consumption of sulfuric acid per unit shows an increasing trend.

[0198] (2) Specifically, the yield of hydrogen fluoride and the consumption of sulfuric acid were investigated under the same mass ratio of fluorosilicic acid solution and sulfuric acid solution, and under different mass concentrations of fluorosilicic acid. As shown in Examples 3 and 7-8, taking a mass ratio of fluorosilicic acid solution to sulfuric acid solution of 1:1.2 as an example: ① As the mass concentration of fluorosilicic acid increases, the content of hydrogen fluoride in the liquid phase shows a decreasing trend, while the content of hydrogen fluoride in the gas phase shows an increasing trend, and the yield of hydrogen fluoride shows an increasing trend. ② As the mass concentration of fluorosilicic acid increases, the consumption of sulfuric acid shows a decreasing trend.

[0199] 4. As shown in Examples 3 and 23-26, in the reaction of fluorosilicic acid solution and sulfuric acid solution, the reaction temperature was controlled at 80 ℃~120 ℃. Taking the mass concentration of fluorosilicic acid in the fluorosilicic acid solution satisfying C1=55% and the mass ratio of fluorosilicic acid solution to sulfuric acid solution being greater than 1:1.2 as an example, the yield trend of hydrogen fluoride under different reaction temperatures was investigated. With the increase of reaction temperature, the change in hydrogen fluoride content in the liquid phase and gas phase was relatively small, and the change in hydrogen fluoride yield was relatively small. In Example 3, the hydrogen fluoride yield was relatively high at a reaction temperature of 100 ℃.

[0200] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0201] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for preparing hydrogen fluoride, wherein, include: A fluorosilicic acid solution is reacted with a sulfuric acid solution to obtain a mixed gas and a fluorinated sulfuric acid; the hydrogen fluoride content in the mixed gas is 10%~20%, and the hydrogen fluoride content in the fluorinated sulfuric acid is 90%~80%. The mixed gas is treated with concentrated sulfuric acid to obtain absorbent sulfuric acid, which is concentrated sulfuric acid after absorbing hydrogen fluoride; The fluorinated sulfuric acid was subjected to falling film evaporation to obtain a hydrogen fluoride gas phase; The hydrogen fluoride-containing gas phase is washed with sulfuric acid to obtain hydrogen fluoride gas.

2. The preparation method according to claim 1, wherein, The mass concentration (C1) of fluorosilicic acid in the fluorosilicic acid solution is 18% to 55%, and the mass concentration of sulfuric acid in the sulfuric acid solution is above 90%.

3. The preparation method according to claim 2, wherein, In the reaction of the fluorosilicic acid solution with the sulfuric acid solution, the mass ratio of the fluorosilicic acid solution to the sulfuric acid solution is 1:1 to 1:

4.

4. The preparation method according to claim 3, wherein, The reaction between the fluorosilicic acid solution and the sulfuric acid solution satisfies one of the following conditions: (i) The mass concentration of fluorosilicic acid in the fluorosilicic acid solution satisfies 18%≤C1<30%, and the mass ratio of the fluorosilicic acid solution to the sulfuric acid solution is 1:2~1:4; (ii) The mass concentration of fluorosilicic acid in the fluorosilicic acid solution satisfies 30%≤C1<40%, and the mass ratio of the fluorosilicic acid solution to the sulfuric acid solution is 1:2~1:3; (iii) The mass concentration of fluorosilicic acid in the fluorosilicic acid solution satisfies 40%≤C1≤55%, and the mass ratio of the fluorosilicic acid solution to the sulfuric acid solution is 1:1~1:

2.

5. The preparation method according to any one of claims 1-4, wherein, The process of washing the hydrogen fluoride-containing gas phase with sulfuric acid further includes obtaining recovered sulfuric acid; the recovered sulfuric acid satisfies at least one of the following: (a) The recovered sulfuric acid serves as the source of the sulfuric acid solution and reacts with the fluorosilicic acid solution; (b) The recovered sulfuric acid component comprises 91% to 95% sulfuric acid and 1% to 5% hydrogen fluoride, calculated as a percentage by mass.

6. The preparation method according to any one of claims 1-4, wherein, In the reaction of fluorosilicic acid solution and sulfuric acid solution, the reaction temperature is controlled at 80 ℃~120 ℃.

7. The preparation method according to any one of claims 1-4, wherein, Also includes: The hydrogen fluoride gas was condensed to obtain crude anhydrous hydrogen fluoride. The crude anhydrous hydrogen fluoride is subjected to distillation and degassing processes to obtain the finished anhydrous hydrogen fluoride.

8. The preparation method according to any one of claims 1-4, wherein, The fluorinated sulfuric acid was further treated by falling film evaporation to obtain a liquid phase containing hydrogen fluoride; The hydrogen fluoride-containing liquid phase is stripped with air to obtain dilute sulfuric acid and stripping gas mixture; The stripping mixture is treated with water absorption to obtain hydrofluoric acid.

9. The preparation method according to any one of claims 1-4, wherein, The mixed gas also includes silicon tetrafluoride, and the mixed gas is further treated with concentrated sulfuric acid to obtain silicon tetrafluoride gas after being absorbed by concentrated sulfuric acid; the silicon tetrafluoride gas after being absorbed by concentrated sulfuric acid is further treated with fluorosilicic acid absorption, filtration and washing to obtain by-product silicon dioxide.

10. A hydrogen fluoride, wherein, The hydrogen fluoride is obtained by the preparation method according to any one of claims 1 to 9.

11. A battery material, wherein, The battery material includes lithium hexafluorophosphate; the raw materials for preparing the battery material include hydrogen fluoride obtained by the preparation method according to any one of claims 1 to 9, or include the hydrogen fluoride according to claim 10.

12. A system for preparing hydrogen fluoride, wherein, include: A decomposition tower, wherein the decomposition tower is provided with liquid phase inlet terminals for fluorosilicic acid solution and sulfuric acid solution; An absorption tower is provided with a liquid phase inlet for concentrated sulfuric acid, and the gas phase inlet of the absorption tower is connected to the gas phase outlet of the decomposition tower. A falling film evaporator, wherein the liquid phase input end of the falling film evaporator is connected to the liquid phase output end of the decomposition tower; The washing tower has a gas phase input end connected to the gas phase output end of the falling film evaporator, a liquid phase input end connected to the liquid phase output end of the absorption tower, and a gas phase output end for hydrogen fluoride gas.

13. The system according to claim 12, wherein, The liquid phase output end of the washing tower is connected to the liquid phase input end of the decomposition tower.

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