Method for treating bisfluorosulfonimide heavy residue

Abstract

Provided in the present application is a method for treating bisfluorosulfonimide heavy residue. The method comprises the following steps: reacting bisfluorosulfonimide heavy residue to be treated with an aqueous solution of an alkaline compound, so as to obtain a reaction solution comprising a salt compound, and ammonia gas; and recovering the reaction solution, so as to obtain the salt compound. By means of the method, the difluorosulfonimide heavy residue can be recycled, thereby improving the economic benefits, and the method is of great significance for promoting sustainable development and recycling economy.

Description

A method for treating double fluorosulfonylimine heavy residue

[0001] The present application claims priority to the Chinese patent application No. 202410803781.1, filed on June 20, 2024, and entitled "A method for treating double fluorosulfonylimine lithium heavy residue", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application belongs to the technical field of chemical recycling process, and relates to a method for treating double fluorosulfonylimine heavy residue. BACKGROUND

[0003] The four key materials of lithium ion batteries include positive electrode, negative electrode, electrolyte and separator. The electrolyte plays a role in transmitting electric charge between the positive and negative electrodes and is a key component of lithium ion batteries. The electrolyte is generally composed of organic solvent, electrolyte salt and a small amount of additives. The electrolyte salt is an important component of the electrolyte. Currently, lithium hexafluorophosphate has become the most important electrolyte lithium salt for commercial lithium ion batteries due to its high conductivity, but it has poor thermal stability and is prone to decomposition due to water absorption. Double fluorosulfonylimine lithium has the advantages of high conductivity, high chemical stability and high thermal stability, and has the potential to replace lithium hexafluorophosphate.

[0004] With the increasing demand for double fluorosulfonylimine lithium in the market, the production of double fluorosulfonylimine lithium by enterprises is also increasing. Currently, double fluorosulfonylimine and lithium-containing compounds are usually used as raw materials to produce double fluorosulfonylimine lithium. However, a large amount of double fluorosulfonylimine heavy residue is usually generated during the production process. Therefore, how to realize the resource recycling of double fluorosulfonylimine heavy residue is a problem to be solved. SUMMARY

[0005] In view of the above defects, the present application provides a method for treating double fluorosulfonylimine heavy residue, which can realize the resource recycling of double fluorosulfonylimine heavy residue.

[0006] The present application provides a method for treating double fluorosulfonylimine heavy residue, comprising the following steps:

[0007] The double fluorosulfonylimine heavy residue to be treated is reacted with an aqueous solution of an alkaline compound to obtain a reaction liquid containing a salt compound and ammonia gas; and the reaction liquid is subjected to recovery treatment to obtain the salt compound.

[0008] Further, the alkaline compound includes at least one of ammonia, alkaline earth metal, alkali metal oxide, alkali metal hydroxide or carbonate.

[0009] Further, the molar ratio of the basic compound to the bisfluorosulfonylimide in the bisfluorosulfonylimide heavy residue is (6-10):1.

[0010] Further, the mass concentration of the aqueous solution of the basic compound is 10-50 wt%.

[0011] Further, the reaction time is 1-24 h.

[0012] Further, the reaction temperature is 80-110°C.

[0013] Further, during the reaction, ion chromatography is used to test the reaction system, and when there is no component of the bisfluorosulfonylimide heavy residue in the reaction system, the reaction is stopped.

[0014] Further, the recovery treatment comprises:

[0015] The reaction liquid comprising the salt compound is subjected to first solid-liquid separation to obtain a first filtrate and the salt compound.

[0016] Further, the first filtrate is subjected to crystallization treatment, and the crystallization treatment comprises:

[0017] The first filtrate is used as a raw liquid to participate in the reaction, and after the salt compound is precipitated, the reaction system is subjected to second solid-liquid separation treatment to obtain a second filtrate and the salt compound.

[0018] Further, the basic compound is at least one of sodium hydroxide, sodium oxide, and sodium carbonate, after the first solid-liquid separation treatment, the salt compound comprises sodium fluoride, the first filtrate comprises sodium sulfate, after the second solid-liquid separation treatment, the salt compound comprises sodium sulfate, and the second filtrate comprises sodium hydroxide and / or sodium carbonate.

[0019] Alternatively, the basic compound is at least one of potassium hydroxide, potassium oxide, and potassium carbonate, after the first solid-liquid separation treatment, the first filtrate comprises potassium sulfate and potassium fluoride, after the second solid-liquid separation treatment, the salt compound comprises potassium sulfate, and the second filtrate comprises potassium fluoride.

[0020] Alternatively, the basic compound is at least one of calcium hydroxide, calcium oxide, and calcium carbonate, after the first solid-liquid separation treatment, the salt compound comprises calcium sulfate and calcium fluoride, and the first filtrate comprises calcium hydroxide and / or calcium carbonate.

[0021] Alternatively, the basic compound is ammonia water and / or ammonium carbonate, after the first solid-liquid separation treatment, the first filtrate comprises ammonium sulfate and ammonium fluoride, after the second solid-liquid separation treatment, the salt compound comprises ammonium sulfate, and the second filtrate comprises ammonium fluoride.

[0022] Further, the salt compound is washed, and the washing liquid is combined into the first filtrate.

[0023] Further, the second filtrate is also used to produce potassium fluoride.

[0024] Alternatively, the second filtrate is used to produce ammonium fluoride.

[0025] Further, the mass percentage of the bisfluorosulfonylimide in the bisfluorosulfonylimide heavy residue is not less than 95wt%.

[0026] The bisfluorosulfonylimide heavy residue treatment method in the present application reacts the bisfluorosulfonylimide heavy residue to be treated with an aqueous solution of an alkaline compound to obtain ammonia gas and a reaction liquid, recovers and processes the reaction liquid to obtain a salt compound, and uses the ammonia gas and the salt compound as raw materials for various chemical production, thereby realizing resource recycling of the bisfluorosulfonylimide heavy residue, bringing economic benefits, and avoiding safety and environmental protection risks. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions, and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present application.

[0028] The present application provides a bisfluorosulfonylimide heavy residue treatment method, which comprises the following steps:

[0029] The bisfluorosulfonylimide heavy residue to be treated is reacted with an aqueous solution of an alkaline compound to obtain a reaction liquid comprising a salt compound and ammonia gas; and the reaction liquid is recovered and processed to obtain the salt compound.

[0030] The bisfluorosulfonylimide heavy residue in the present application is obtained by removing impurities from the produced bisfluorosulfonylimide through purification, and collecting the remaining components after distillation of the bisfluorosulfonylimide. The main components of the bisfluorosulfonylimide heavy residue include bisfluorosulfonylimide, fluorosulfonic acid, and fluoride salt, wherein the fluoride salt includes any one of sodium fluoride, potassium fluoride, and ammonium fluoride.

[0031] The present application does not make specific limitations on the reaction temperature, the reaction time, the type of the alkaline compound, the molar ratio of the alkaline compound to the bisfluorosulfonylimide in the bisfluorosulfonylimide heavy residue, and the mass concentration of the aqueous solution of the alkaline compound, as long as the alkaline compound and the bisfluorosulfonylimide are fully reacted.

[0032] The method for treating bisfluorosulfone imide heavy residue in the present application is to make the bisfluorosulfone imide heavy residue react with the aqueous solution of the alkaline compound, and the bisfluorosulfone imide and fluorosulfonic acid in the heavy residue are hydrolyzed, the hydrolysis products of the bisfluorosulfone imide are sulfuric acid, ammonium bisulfate and hydrofluoric acid, the hydrolysis products of the fluorosulfonic acid are sulfuric acid and hydrofluoric acid, these hydrolysis products further react with the alkaline compound to obtain a reaction liquid and ammonia gas, the reaction liquid includes salt compounds such as sulfate and fluoride salt, and the salt compounds can be obtained by recycling and treating the reaction liquid, the reaction principle is shown in formula 1, formula 2, formula 3, formula 4 and formula 5. The obtained ammonia gas and salt compounds are collected and used as raw materials in different chemical production, which not only can reduce the emission of chemical waste and environmental pollution, but also can realize the recycling and utilization of bisfluorosulfone imide heavy residue, improve economic benefits, realize the unity of economy and environmental benefits, and has important significance for promoting sustainable development and circular economy.

[0033] In an embodiment, the alkaline compound includes at least one of ammonia, an oxide of an alkaline earth metal, an oxide of an alkali metal, a hydroxide of an alkali metal, or a carbonate of an alkali metal. When the alkaline compound includes two or more of the aforementioned compounds, the present application does not specifically limit the ratio between each compound.

[0034] The present application does not specifically limit the types of alkaline earth metal and alkali metal, and the source of the alkaline compound, for example, commercially available products or products prepared by conventional preparation methods known to those skilled in the art can be used.

[0035] In an embodiment, the molar ratio of the alkaline compound to the bisfluorosulfone imide in the bisfluorosulfone imide heavy residue is (6-10):1. Within this range, the alkaline compound and the bisfluorosulfone imide heavy residue are fully reacted, the bisfluorosulfone imide and fluorosulfonic acid in the bisfluorosulfone imide heavy residue are more completely reacted, and the treatment effect is improved.

[0036] In an embodiment, the mass concentration of the aqueous solution of the alkaline compound is 10-50 wt%. When the mass concentration of the aqueous solution of the alkaline compound is within the aforementioned range, better treatment effect can be achieved, the bisfluorosulfone imide and fluorosulfonic acid can be fully hydrolyzed, and the hydrolysis products and the alkaline compound can better react to completely convert into ammonia gas and salt compounds; at the same time, the amount of the alkaline compound can be reduced to avoid waste and reduce costs while ensuring complete reaction.

[0037] In an embodiment, the reaction temperature is 80-110°C. Within this range, the bisfluorosulfone imide and fluorosulfonic acid are fully hydrolyzed, which further promotes the reaction of the hydrolysis products and the alkaline compound, and further improves the treatment effect.

[0038] In one embodiment, the reaction time is 1-24 hours. Within this range, the bisfluorosulfonylimide heavy residue can be ensured to react sufficiently with the basic compound, and the processing time is controlled within an appropriate range, which is beneficial to improve the processing efficiency.

[0039] In one embodiment, ion chromatography is used to test the reaction system during the reaction, and the reaction is stopped when there is no component of the bisfluorosulfonylimide heavy residue in the reaction system. By using ion chromatography to detect the reaction system during the reaction, the content of bisfluorosulfonylimide and fluorosulfonic acid in the reaction system can be monitored to ensure that the bisfluorosulfonylimide heavy residue component in the reaction system has been completely reacted at the end of the reaction, thereby improving the processing effect.

[0040] In one embodiment, the recovery processing includes: performing a first solid-liquid separation on the reaction liquid containing the salt compound to obtain a first filtrate and the salt compound.

[0041] It can be understood that the salt compound obtained after the reaction ends can contain components that are insoluble in the reaction liquid.

[0042] Specifically, when the basic compound is at least one of sodium hydroxide, sodium oxide, and sodium carbonate, the bisfluorosulfonylimide heavy residue is processed, and after the reaction ends, gaseous ammonia and / or carbon dioxide are generated, as well as precipitated sodium fluoride and water-soluble sodium sulfate present in the reaction system. By collecting the gaseous ammonia and / or carbon dioxide and performing a first solid-liquid separation on the reaction system, the salt compound sodium fluoride can be obtained.

[0043] When the basic compound is at least one of calcium hydroxide, calcium oxide, and calcium carbonate, the bisfluorosulfonylimide heavy residue is processed, and after the reaction ends, gaseous ammonia and / or carbon dioxide are generated, as well as precipitated calcium fluoride and calcium sulfate present in the reaction system. By performing a first solid-liquid separation, the salt compounds calcium fluoride and calcium sulfate can be obtained. The mixture of calcium fluoride and calcium sulfate can be used to prepare cement.

[0044] It can be understood that, in order to completely react the bisfluorosulfonylimide and fluorosulfonic acid in the bisfluorosulfonylimide heavy residue, an excess of the basic compound is often added during the actual reaction. Therefore, the first filtrate also includes unreacted basic compounds. For example, when the basic compound is at least one of sodium hydroxide, sodium oxide, and sodium carbonate, the first filtrate also includes sodium hydroxide and / or sodium carbonate; when the basic compound is at least one of calcium hydroxide, calcium oxide, and calcium carbonate, the first filtrate also includes calcium hydroxide and / or calcium carbonate.

[0045] In a specific embodiment, the crystallization treatment comprises: participating the first filtrate as a raw material liquid in the reaction until the salt compound is precipitated, and then performing a second solid-liquid separation treatment on the reaction system to obtain a second filtrate and the salt compound.

[0046] In the present application, the salt compound is obtained by the first solid-liquid separation and / or the second solid-liquid separation.

[0047] It can be understood that the salt compound obtained by the reaction can also contain components dissolved in the reaction liquid. In order to obtain the salt compound dissolved in the reaction liquid, after the first solid-liquid separation to remove the salt compound not dissolved in the reaction liquid, the first filtrate needs to be subjected to a crystallization treatment to separate the salt compound dissolved in the reaction liquid.

[0048] The raw material liquid in the present application refers to the liquid obtained by the reaction of the double-fluorosulfonyl imide heavy residue and the alkaline compound.

[0049] Specifically, when the alkaline compound is at least one of sodium hydroxide, sodium oxide and sodium carbonate, the first filtrate containing sodium sulfate can be obtained after the first solid-liquid separation treatment of the reaction system obtained after the treatment of the double-fluorosulfonyl imide heavy residue of the previous batch; by using the first filtrate obtained in the previous batch as a raw material liquid for the reaction in the double-fluorosulfonyl imide heavy residue treatment of the next batch, gaseous ammonia and / or carbon dioxide, precipitated sodium fluoride and water-soluble sodium sulfate existing in the reaction system can be generated again, and the first solid-liquid separation of the reaction system can obtain the salt compound sodium fluoride and the first filtrate containing sodium sulfate; by recycling the first filtrate containing sodium sulfate obtained in the previous batch for the double-fluorosulfonyl imide heavy residue treatment of the next batch, the mass concentration of sodium sulfate in the first filtrate gradually increases with the increase of the recycling times, and the temperature of the reaction system is reduced to 20-25℃, the sodium sulfate crystals are precipitated, and the second solid-liquid separation can obtain the salt compound sodium sulfate.

[0050] When the basic compound is at least one of potassium hydroxide, potassium oxide, and potassium carbonate, after the treatment of the previous batch of double fluorosulfonyl imine heavy residues is completed, gaseous ammonia and / or carbon dioxide, and water-soluble potassium fluoride and potassium sulfate existing in the reaction system are obtained, and the reaction system is subjected to first solid-liquid separation treatment, and a first filtrate including potassium fluoride and potassium sulfate can be obtained; by taking the first filtrate obtained in the previous batch as a raw material liquid, the first filtrate is used for reaction in the treatment of the next batch of double fluorosulfonyl imine heavy residues, and gaseous ammonia and / or carbon dioxide, and water-soluble potassium fluoride and potassium sulfate existing in the reaction system are generated again, and the reaction system is subjected to first solid-liquid separation, and a first filtrate including potassium fluoride and potassium sulfate can be obtained; the cycle is repeated, that is, by taking the first filtrate including potassium fluoride and potassium sulfate obtained in the previous batch for the treatment of the next batch of double fluorosulfonyl imine heavy residues, as the number of cycles increases, the mass concentration of potassium fluoride and potassium sulfate in the first filtrate gradually increases, and by using the solubility difference between potassium fluoride and potassium sulfate, when the mass concentration of potassium fluoride in the first filtrate is 25-30 wt%, the temperature of the reaction system is reduced to 20-25°C, potassium sulfate crystals are precipitated, second solid-liquid separation is performed, and salt compound potassium sulfate crystals and a second filtrate including potassium fluoride are obtained.

[0051] When the basic compound is ammonia and / or ammonium carbonate, after the treatment of the previous batch of double fluorosulfonyl imine heavy residues is completed, gaseous ammonia and / or carbon dioxide, and water-soluble ammonium fluoride and ammonium sulfate existing in the reaction system are obtained, and the reaction system is subjected to first solid-liquid separation treatment, and a first filtrate including ammonium fluoride and ammonium sulfate can be obtained; by taking the first filtrate obtained in the previous batch as a raw material liquid, the first filtrate is used for reaction in the treatment of the next batch of double fluorosulfonyl imine heavy residues, and gaseous ammonia and / or carbon dioxide, and water-soluble ammonium fluoride and ammonium sulfate existing in the reaction system are generated again, and the reaction system is subjected to first solid-liquid separation, and a first filtrate including ammonium fluoride and ammonium sulfate can be obtained; the cycle is repeated, that is, by taking the first filtrate including ammonium fluoride and ammonium sulfate obtained in the previous batch for the treatment of the next batch of double fluorosulfonyl imine heavy residues, as the number of cycles increases, the mass concentration of ammonium fluoride and ammonium sulfate in the first filtrate gradually increases, and by using the solubility difference between ammonium fluoride and ammonium sulfate, when the mass concentration of ammonium fluoride in the first filtrate is 25-30 wt%, the temperature of the reaction system is reduced to 20-25°C, ammonium sulfate crystals are precipitated, second solid-liquid separation is performed, and salt compound ammonium sulfate crystals and a second filtrate including ammonium fluoride are obtained.

[0052] It can be understood that the basic compound is consumed to a certain extent during the reaction, and therefore the mass content of the basic compound in the filtrate after solid-liquid separation is low. When the first filtrate is used as a raw material liquid for reaction, the basic compound needs to be added to the filtrate to ensure that the double fluorosulfonyl imine heavy residues are fully reacted and the treatment effect is improved.

[0053] In one specific embodiment, the basic compound is at least one of sodium hydroxide, sodium oxide, and sodium carbonate, after the first solid-liquid separation treatment, the salt compound comprises sodium fluoride, the first filtrate comprises sodium sulfate, after the second solid-liquid separation treatment, the salt compound comprises sodium sulfate, and the second filtrate comprises sodium hydroxide and / or sodium carbonate;

[0054] Alternatively, the basic compound is at least one of potassium hydroxide, potassium oxide, and potassium carbonate, after the first solid-liquid separation treatment, the first filtrate comprises potassium sulfate and potassium fluoride, after the second solid-liquid separation treatment, the salt compound comprises potassium sulfate, and the second filtrate comprises potassium fluoride;

[0055] Alternatively, the basic compound is at least one of calcium hydroxide, calcium oxide, and calcium carbonate, after the first solid-liquid separation treatment, the salt compound comprises calcium sulfate and calcium fluoride, and the first filtrate comprises calcium hydroxide and / or calcium carbonate;

[0056] Alternatively, the basic compound is ammonia and / or ammonium carbonate, after the first solid-liquid separation treatment, the first filtrate comprises ammonium sulfate and ammonium fluoride, after the second solid-liquid separation treatment, the salt compound comprises ammonium sulfate, and the second filtrate comprises ammonium fluoride.

[0057] Through the above operation, the obtained salt compound can be used as a raw material in different chemical production, thereby realizing the recycling of the double fluorosulfonyl imine heavy residue and reducing environmental pollution.

[0058] In one specific embodiment, the salt compound is washed, and the washing liquid is combined into the first filtrate. The liquid used for washing in the present application is not specifically limited as long as it meets the purpose of the present application, for example, the liquid used for washing the salt compound can be deionized water. By washing the salt compound to remove impurities and combining the washing liquid into the first filtrate as a raw liquid for reaction, not only the purity of the salt compound can be improved, but also the waste liquid generated in the process can be recycled again, thereby further reducing the cost and reducing environmental pollution.

[0059] In one specific embodiment, the double fluorosulfonyl imine heavy residue treatment method further comprises producing potassium fluoride by using the second filtrate;

[0060] Alternatively, ammonium fluoride is produced by using the second filtrate.

[0061] Specifically, when the basic compound is at least one of potassium oxide, potassium hydroxide, and potassium carbonate, potassium fluoride is included in the second filtrate, and the filtrate can be used to prepare a potassium fluoride product.

[0062] The method for preparing the potassium fluoride product is not specifically limited in the present application, and a conventional method can be used for preparation.

[0063] When the basic compound is ammonia water and / or ammonium carbonate, the second filtrate includes ammonium fluoride, and the filtrate can be used to prepare an ammonium fluoride product.

[0064] The method for preparing the ammonium fluoride product is not particularly limited, and a conventional method can be used.

[0065] The second filtrate can be further treated to obtain a potassium fluoride or ammonium fluoride product, or used as a raw material for other production, thereby maximizing the economy.

[0066] In one specific embodiment, the ammonia gas is further absorbed.

[0067] When the basic compound is at least one of ammonia water, an alkaline earth metal, an oxide or a hydroxide of an alkali metal, ammonia gas is generated after the reaction is completed. At this time, the ammonia gas can be absorbed by pure water to obtain ammonia water. Since ammonia water has multiple uses as an important reagent, it can be used as an analytical reagent, an alkaline disinfectant, a neutralizing agent, a detergent, etc., thereby further improving the economic benefits. Preferably, the mass concentration of the ammonia water is 20-35 wt%.

[0068] When the basic compound includes at least one of ammonium carbonate, a carbonate of an alkaline earth metal or an alkali metal, the generated gas phase after the reaction is completed includes ammonia gas and carbon dioxide. At this time, the gas phase obtained by the reaction can also be absorbed by pure water. Since carbon dioxide is more difficult to dissolve in water than ammonia gas at normal temperature and pressure, the ammonia water obtained by absorption by pure water can be used in fields with less stringent requirements for purity.

[0069] In one specific embodiment, the mass percentage of the bisfluorosulfonylimide in the bisfluorosulfonylimide heavy residue is not less than 95 wt%. Within this range, not only can a good treatment effect be achieved, but also the cost can be reduced due to the low content of bisfluorosulfonylimide in the heavy residue, thereby achieving higher economy.

[0070] Hereinafter, the method for treating bisfluorosulfonylimide heavy residue according to the present application will be described in detail through specific examples.

[0071] Example 1

[0072] The first batch of 500g of difluorosulfone heavy residue (mass percentage of 95wt% of difluorosulfone) is mixed with 6.3kg of sodium hydroxide aqueous solution (mass concentration of 10wt%), wherein the molar ratio of the alkaline compound to difluorosulfone in the difluorosulfone heavy residue is 6:1, and the temperature is increased to 100℃ for reaction. During the reaction, ion chromatography is used to test the reaction system, and when there is no component of the difluorosulfone heavy residue in the reaction system, the reaction is stopped, and the reaction time is 5h. The reaction system and ammonia gas are obtained, and the ammonia gas is absorbed by pure water to obtain an ammonia water solution with a concentration of 25wt%. The reaction system is filtered to obtain a filter cake of sodium fluoride and a first filtrate containing sodium sulfate. The filter cake is washed with deionized water to obtain a washing liquid, and the first filtrate and the washing liquid are combined. Sodium hydroxide is added to the combined solution to a pH equivalent to that of a 10wt% sodium hydroxide aqueous solution, and the solution is used as raw material liquid for the next batch of reaction and recycled multiple times. During the reaction, the concentration of sodium sulfate in the first filtrate gradually increases, and when the concentration of sodium sulfate in the first filtrate is higher than its solubility at 20℃, the temperature of the reaction system is reduced to 20℃, and sodium sulfate crystals are precipitated. After the second solid-liquid separation, sodium sulfate and a second filtrate are obtained. The second filtrate is used as raw material liquid for the next batch of reaction.

[0073] Example 2

[0074] The first batch of 1000g of difluorosulfone heavy residue (mass percentage of 96wt% of difluorosulfone) is mixed with 15.8kg of potassium hydroxide aqueous solution (mass concentration of 15wt%), wherein the molar ratio of the alkaline compound to difluorosulfone in the difluorosulfone heavy residue is 8:1, and the temperature is increased to 80℃ for reaction. During the reaction, ion chromatography is used to test the reaction system, and when there is no component of the difluorosulfone heavy residue in the reaction system, the reaction is stopped, and the reaction time is 6h. The reaction system and ammonia gas are obtained, and the reaction system is subjected to a first solid-liquid separation to obtain a first filtrate containing potassium fluoride and potassium sulfate. The first filtrate obtained in the first batch is used as raw material liquid, and potassium hydroxide is added to the first filtrate to a pH equivalent to that of a 15wt% potassium hydroxide aqueous solution, and the first filtrate is used for the next batch of difluorosulfone heavy residue treatment and recycled multiple times. As the reaction proceeds, the mass concentration of potassium fluoride and potassium sulfate in the first filtrate gradually increases, and the solubility difference between potassium fluoride and potassium sulfate is utilized. When the mass concentration of potassium fluoride in the first filtrate is 25-30wt%, the temperature of the reaction system is reduced to 20℃, and potassium sulfate crystals are precipitated. After the second solid-liquid separation, a salt compound potassium sulfate crystal and a second filtrate containing potassium fluoride are obtained. Ammonia gas is absorbed by pure water to obtain an ammonia water solution with a concentration of 21wt%. By further processing the second filtrate, hydrogen fluoride aqueous solution is added to the filtrate until it is neutral, and potassium fluoride product is obtained.

[0075] Example 3

[0076] The first batch of 1000g of difluorosulfone heavy residue (mass percentage of 95wt%) was mixed with 24.7kg of calcium hydroxide suspension (mass concentration of 11wt%), the molar ratio of the basic compound to difluorosulfone in the heavy residue was 7:1, and the temperature was raised to 110°C for reaction. During the reaction, ion chromatography was used to test the reaction system, and when there was no component of the difluorosulfone heavy residue in the reaction system, the reaction was stopped, the reaction time was 3h, and gaseous ammonia, precipitated calcium fluoride and calcium sulfate in the reaction system were generated. The ammonia was absorbed by pure water to obtain an ammonia solution with a concentration of 18wt%. The reaction liquid was filtered to obtain a filter cake containing calcium sulfate and calcium fluoride and a first filtrate. The calcium sulfate and calcium fluoride were washed with water to obtain a washing liquid, which was mixed with the first filtrate and supplemented with calcium hydroxide to a pH comparable to that of the calcium hydroxide suspension with a mass concentration of 11wt%, and the mixture could be used as a raw material liquid to continue to participate in the reaction; the mixture of calcium sulfate and calcium fluoride could be used to prepare cement.

[0077] Example 4

[0078] The first batch of 1000g of difluorosulfone heavy residue (mass percentage of 96wt%) was mixed with 6kg of ammonia solution (mass concentration of 15wt%), the molar ratio of the basic compound to difluorosulfone in the heavy residue was 10:1, and the temperature was raised to 80°C for reaction. During the reaction, ion chromatography was used to test the reaction system, and when there was no component of the difluorosulfone heavy residue in the reaction system, the reaction was stopped, the reaction time was 6h, and the reaction system and ammonia were obtained. The first solid-liquid separation treatment was performed on the reaction system to obtain a first filtrate containing ammonium fluoride and ammonium sulfate. The first filtrate obtained in the first batch was used as a raw material liquid, and ammonia was added to the first filtrate to a pH comparable to that of the ammonia solution with a mass concentration of 15wt%, and the mixture was used for reaction in the next batch of difluorosulfone heavy residue treatment, and the cycle was repeated multiple times. As the reaction proceeded, the mass concentration of ammonium fluoride and ammonium sulfate in the first filtrate gradually increased. When the mass concentration of ammonium fluoride in the first filtrate was 25-30wt%, the temperature of the reaction system was lowered to 20°C, ammonium sulfate crystals were precipitated, and a second solid-liquid separation was performed to obtain salt compound ammonium sulfate crystals and a second filtrate containing ammonium fluoride. Ammonia was absorbed by pure water to obtain an ammonia solution with a concentration of 21wt%. By further treating the filtrate, adding hydrogen fluoride solution to the filtrate to neutralize the filtrate, ammonium fluoride product was obtained.

[0079] Example 5

[0080] The first batch of 944.4 g of difluorosulfone heavy residue (mass percentage content of 95 wt% of difluorosulfone) was mixed with 6.3 kg of sodium carbonate aqueous solution (mass concentration of 50 wt%), wherein the molar ratio of the basic compound to difluorosulfone in the difluorosulfone heavy residue was 6:1, and the temperature was increased to 85°C for reaction. During the reaction, ion chromatography was used to test the reaction system. When there was no component of the difluorosulfone heavy residue in the reaction system, the reaction was stopped, and the reaction time was 5 h. The reaction system, ammonia gas and carbon dioxide were obtained. The reaction system was filtered to obtain filter cake sodium fluoride and a first filtrate including sodium sulfate. The filter cake was washed with deionized water to obtain a washing liquid. The first filtrate and the washing liquid were combined, and sodium carbonate was added to the combined liquid to a pH equivalent to that of the sodium carbonate aqueous solution with a mass concentration of 50%, which was used as raw material liquid for the next batch of reaction and recycled multiple times. During the reaction, the concentration of sodium sulfate gradually increased. When the concentration of sodium sulfate in the filtrate was higher than its solubility at 20°C, the temperature of the reaction system was reduced to 20°C, and sodium sulfate crystals were precipitated. After the second solid-liquid separation, sodium sulfate and a second filtrate were obtained. The second filtrate was used as raw material liquid for the reaction. The mixed gas of ammonia gas and carbon dioxide was introduced into pure water, and ammonia gas was completely absorbed, and a small amount of carbon dioxide was absorbed. The absorbed solution was an ammonia water solution with slightly poor purity, which could be used in fields such as metal surface oil removal, rust removal, cleaning and polishing, which had low requirements for the purity of ammonia water.

[0081] Example 6

[0082] The first batch of 1078 g of difluorosulfamide heavy residue (96 wt% of difluorosulfamide) is mixed with 15.8 kg of potassium carbonate aqueous solution (30 wt% of mass concentration), the molar ratio of the alkaline compound to difluorosulfamide in the difluorosulfamide heavy residue is 6:1, and the temperature is increased to 90°C for reaction. During the reaction, the reaction system is tested by ion chromatography. When there is no component of the difluorosulfamide heavy residue in the reaction system, the reaction is stopped, and the reaction time is 12 h. The reaction system, ammonia gas and carbon dioxide are obtained, and the first solid-liquid separation is performed on the reaction system to obtain the first filtrate including potassium fluoride and potassium sulfate. The first filtrate obtained in the first batch is used as raw material liquid, and potassium carbonate is added to the first filtrate to reach the pH of the potassium carbonate aqueous solution with a mass concentration of 30 wt%, and the first filtrate is used for reaction in the next batch of difluorosulfamide heavy residue treatment. The first filtrate is recycled for multiple times. As the reaction proceeds, the mass concentration of potassium fluoride and potassium sulfate in the first filtrate gradually increases. When the mass concentration of potassium fluoride in the first filtrate is 25-30 wt%, the temperature of the reaction system is decreased to 20°C, and potassium sulfate crystals are precipitated. The second solid-liquid separation is performed to obtain the salt compound potassium sulfate crystals and the second filtrate including potassium fluoride. The second filtrate is further treated by adding hydrogen fluoride aqueous solution to the filtrate until the filtrate is neutral to obtain the potassium fluoride product. The mixed gas of ammonia gas and carbon dioxide is introduced into pure water, and the ammonia gas is completely absorbed, and a small amount of carbon dioxide is absorbed. The solution after absorption is an ammonia water solution with slightly poor purity, which can be used in fields with low requirements on the purity of ammonia water, such as metal surface oil removal, rust removal, cleaning and polishing.

[0083] Example 7

[0084] The first batch of 2016 g of difluorosulfone heavy residue (mass percentage of 95 wt%) was mixed with 24.7 kg of calcium carbonate suspension (mass concentration of 30 wt%), wherein the molar ratio of the basic compound to difluorosulfone in the difluorosulfone heavy residue was 7:1, and the temperature was increased to 95°C for reaction. During the reaction, ion chromatography was used to test the reaction system. When there was no component of the difluorosulfone heavy residue in the reaction system, the reaction was stopped, and the reaction time was 18 h. Gas-phase ammonia and carbon dioxide were generated, and precipitated calcium fluoride and calcium sulfate existed in the reaction system. The reaction liquid was filtered to obtain a filter cake including calcium sulfate and calcium fluoride and a filtrate. The calcium sulfate and calcium fluoride were water-washed to obtain a washing liquid. The washing liquid was mixed with the filtrate, and calcium carbonate was added to the mixture until the pH was equivalent to that of the calcium carbonate suspension with a mass concentration of 30 wt%. The mixture can be used as a raw material liquid to continue participating in the reaction. The mixture of calcium sulfate and calcium fluoride can be used to prepare cement. The mixed gas of ammonia and carbon dioxide was passed into pure water, and the ammonia was completely absorbed, and a small amount of carbon dioxide was absorbed. The solution after absorption was an ammonia water solution with slightly poor purity, which can be used in fields such as metal surface oil removal, rust removal, cleaning, and polishing, which have low requirements for the purity of ammonia water.

[0085] Example 8

[0086] The first batch of 235.8 g of difluorosulfone heavy residue (96 wt% of difluorosulfone) is mixed with 6 kg of ammonium carbonate solution (15 wt% of mass concentration), the molar ratio of the basic compound to difluorosulfone in the difluorosulfone heavy residue is 7.5:1, and the temperature is increased to 105°C for reaction. During the reaction, the reaction system is tested by ion chromatography. When there is no component of the difluorosulfone heavy residue in the reaction system, the reaction is stopped, and the reaction time is 24 h. The reaction system, ammonia gas and carbon dioxide are obtained, and the first solid-liquid separation is performed on the reaction system to obtain the first filtrate containing ammonium fluoride and ammonium sulfate. The first filtrate obtained in the first batch is used as the raw material liquid, and ammonium carbonate is added to the first filtrate to make the pH of the first filtrate equivalent to that of the 15 wt% ammonium carbonate aqueous solution, and the first filtrate is used for the reaction of the difluorosulfone heavy residue in the next batch. The first filtrate is recycled for multiple times. As the reaction proceeds, the mass concentration of ammonium fluoride and ammonium sulfate in the first filtrate gradually increases. When the mass concentration of ammonium fluoride in the first filtrate is 25-30 wt%, the temperature of the reaction system is reduced to 20°C, and ammonium sulfate crystals are precipitated. The second solid-liquid separation is performed to obtain the salt compound ammonium sulfate crystals and the second filtrate containing ammonium fluoride. The second filtrate is further treated by adding hydrogen fluoride aqueous solution to the second filtrate until the second filtrate is neutral, and the ammonium fluoride product is obtained. The mixed gas of ammonia gas and carbon dioxide is introduced into pure water, and the ammonia gas is completely absorbed, and a small amount of carbon dioxide is absorbed. The absorbed solution is an ammonia water solution with slightly poor purity, which can be used in fields such as metal surface oil removal, rust removal, cleaning and polishing, and the like, which have low requirements for the purity of ammonia water.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for treating bis(fluorosulfonyl)imide heavy residue, characterized in that, Includes the following steps: The bis(fluorosulfonyl)imide residue to be treated is reacted with an aqueous solution of an alkaline compound to obtain a reaction solution containing salt compounds and ammonia gas; the reaction solution is then recovered to obtain the salt compounds.

2. The method for treating bis(fluorosulfonyl)imide heavy slag according to claim 1, characterized in that, The alkaline compound includes at least one of ammonia, alkaline earth metal, oxide of alkali metal, hydroxide of alkali metal, or carbonate.

3. The method for treating bis(fluorosulfonyl)imide heavy slag according to claim 1 or 2, characterized in that, The molar ratio of the alkaline compound to the difluorosulfonyl imide in the difluorosulfonyl imide heavy residue is 6-10:1; And / or, the aqueous solution of the alkaline compound has a mass concentration of 10–50 wt%; And / or, the reaction time is 1 h to 24 h; And / or, the temperature of the reaction is 80°C to 110°C.

4. The method for treating bis(fluorosulfonyl)imide heavy slag according to any one of claims 1-3, characterized in that, During the reaction, the reaction system was subjected to ion chromatography. The reaction was stopped when no bis(fluorosulfonyl)imide heavy residue was found in the reaction system.

5. The method for treating bis(fluorosulfonyl)imide heavy slag according to any one of claims 1-4, characterized in that, The recycling process includes: The reaction solution containing the salt compound is subjected to a first solid-liquid separation to obtain a first filtrate and the salt compound.

6. The method for treating bis(fluorosulfonyl)imide heavy slag according to claim 5, characterized in that, The first filtrate is subjected to crystallization treatment, the crystallization treatment comprising: The first filtrate is used as a raw material in the reaction until the salt compound precipitates. Then, the reaction system is subjected to a second solid-liquid separation process to obtain the second filtrate and the salt compound.

7. The method for treating bis(fluorosulfonyl)imide heavy slag according to claim 6, characterized in that, The alkaline compound is at least one of sodium hydroxide, sodium oxide, and sodium carbonate. After the first solid-liquid separation treatment, the salt compound includes sodium fluoride, and the first filtrate includes sodium sulfate. After the second solid-liquid separation treatment, the salt compound includes sodium sulfate, and the second filtrate includes sodium hydroxide and / or sodium carbonate. Alternatively, the alkaline compound is at least one of potassium hydroxide, potassium oxide, and potassium carbonate; after the first solid-liquid separation treatment, the first filtrate includes potassium sulfate and potassium fluoride; after the second solid-liquid separation treatment, the salt compound includes potassium sulfate, and the second filtrate includes potassium fluoride. Alternatively, the alkaline compound is at least one of calcium hydroxide, calcium oxide, and calcium carbonate; after the first solid-liquid separation treatment, the salt compound includes calcium sulfate and calcium fluoride; and the first filtrate includes calcium hydroxide and / or calcium carbonate. Alternatively, the alkaline compound is ammonia and / or ammonium carbonate, and after the first solid-liquid separation treatment, the first filtrate includes ammonium sulfate and ammonium fluoride; after the second solid-liquid separation treatment, the salt compound includes ammonium sulfate, and the second filtrate includes ammonium fluoride.

8. The method for treating bis(fluorosulfonyl)imide heavy slag according to claim 6 or 7, characterized in that, The salt compound is washed, and the washing liquid is combined with the first filtrate.

9. The method for treating bis(fluorosulfonyl)imide heavy slag according to any one of claims 6-8, characterized in that, It also includes the production of potassium fluoride using the second filtrate; Alternatively, ammonium fluoride can be produced using the second filtrate.

10. The method for treating bis(fluorosulfonyl)imide heavy slag according to any one of claims 1-9, characterized in that, The mass percentage of bis(fluorosulfonyl)imide in the bis(fluorosulfonyl)imide heavy residue is not less than 95 wt%.

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