CN113474327B

CN113474327B - Method for treating acesulfame potassium waste liquid

Info

Publication number: CN113474327B
Application number: CN202180001408.9A
Authority: CN
Inventors: 周睿; 丁震; 陈永旭; 郑仁峰; 杨峰宝
Original assignee: Anhui Jinhe Industrial Co Ltd
Current assignee: Anhui Jinhe Industrial Co Ltd
Priority date: 2021-05-28
Filing date: 2021-05-28
Publication date: 2023-09-26
Anticipated expiration: 2041-05-28
Also published as: CN113474327A; WO2022246863A1

Abstract

The application provides a method for treating acesulfame potassium waste liquid, which comprises the following steps: adding first liquid ammonia into acesulfame waste liquid, and carrying out neutralization reaction in a closed reactor under preset conditions to obtain a first material; separating the first material into a first organic phase and a first aqueous phase, and evaporating the first aqueous phase until the water content reaches a preset water content to obtain a second material; adding second liquid ammonia into the second material, and carrying out neutralization reaction in a closed reactor under preset conditions to obtain a third material; separating the third material into a second organic phase and a second aqueous phase; recovering the first organic phase and the second organic phase as a crude triethylamine product; and carrying out solid-liquid separation on the second water phase to obtain an ammonium sulfate crude product and a residual liquid. The method has the advantages of quick reaction, high triethylamine sulfate conversion rate and more thorough reaction; simplifying the processing technology of acesulfame waste liquid, shortening the processing time and improving the recovery efficiency of amine.

Description

Method for treating acesulfame potassium waste liquid

Technical Field

The application belongs to the technical field of fine chemical engineering, and particularly relates to a treatment method of acesulfame potassium waste liquid.

Background

The acesulfame potassium (acesulfame potassium) is also called AK sugar, is a widely used food additive, has white crystalline powder appearance, is used as an organic synthetic salt, has similar taste to sugarcane, is easy to dissolve in water and slightly dissolve in alcohol, has stable chemical property and is not easy to generate decomposition failure; does not participate in metabolism of the organism and does not provide energy; the sweetness is high and the price is low; has no caries causing property; has good heat and acid stability.

Currently, in the synthesis of acesulfame potassium, a diketene-sulfur trioxide method is generally adopted, and the specific reaction steps comprise: reacting sulfamic acid with an amine to form an amine salt of sulfamic acid, and then reacting the amine salt of sulfamic acid with diketene to form an acetoacetamide salt; in the presence of sulfur trioxide, performing cyclization reaction on the acetyl acetamide salt to form a cyclic sulfur trioxide adduct; hydrolyzing the cyclic compound to obtain a hydrolysate; the hydrolysate was then treated with potassium hydroxide to obtain acesulfame potassium (ASK).

In the production process, when the sulfamic acid and the diketene are subjected to the addition reaction, amine, especially triethylamine, is used as a reaction catalyst, and after the final product ASK is obtained, the rest of the waste water mainly contains sulfate of the amine, sulfuric acid, impurity organic matters (including triethylamine), solvents and the like, and the rest of the waste water can be discharged after being treated; but on the one hand this would result in a great deal of disposal costs and on the other hand the amines in the waste water would have a high economic value and the emission would be wasteful of resources.

In the prior art, there are treatment methods for producing ammonium sulfate and recovering amine by reacting ammonia (ammonia gas, liquid ammonia, etc.) with sulfate and sulfuric acid of amine, such as chinese patent CN103097297a, chinese patent CN111630039a, chinese patent CN112142602a, etc., but these methods all have problems of complex reaction process, long process and low recovery efficiency.

Disclosure of Invention

The present application has been made in view of the above problems, and has as its object to provide a method for treating acesulfame potassium waste liquid which overcomes or at least partially solves the above problems.

According to one aspect of the application, there is provided a method for treating acesulfame potassium waste liquid, which is waste liquid produced by preparing acesulfame potassium by a diketene-sulfur trioxide method, comprising:

a first neutralization step: adding first liquid ammonia into acesulfame waste liquid, and carrying out neutralization reaction in a closed reactor under preset conditions to obtain a first material;

a first separation step: separating the first material into a first organic phase and a first aqueous phase, and evaporating the first aqueous phase until the water content reaches a preset water content to obtain a second material;

and a second neutralization step: adding second liquid ammonia into the second material, and carrying out neutralization reaction in a closed reactor under preset conditions to obtain a third material;

a second separation step: separating the third material into a second organic phase and a second aqueous phase; and

and (3) a product recovery step: recovering the first organic phase and the second organic phase as a crude triethylamine product; and carrying out solid-liquid separation on the second water phase to obtain an ammonium sulfate crude product and a residual liquid.

Optionally, in the above method, the acesulfame potassium waste liquid comprises, based on the total mass of the acesulfame potassium waste liquid: 10-30wt% of sulfuric acid, 5-20wt% of triethylamine sulfate and 3-5wt% of impurity organic matters.

Optionally, in the method, the molar ratio of the total amount of the first liquid ammonia to the second liquid ammonia to sulfate radical in the acesulfame waste liquid is 2.5-4:1.

Optionally, in the above method, the ratio of the first liquid ammonia to the second liquid ammonia is 3-4:1-2.

Optionally, in the above method, the first neutralization step further includes: after the neutralization reaction is finished, distilling the obtained first material to remove excessive ammonia;

the second neutralization step further comprises: after the neutralization reaction is finished, the obtained second material is distilled to remove excessive ammonia gas.

Alternatively, in the above-mentioned method, in the first separation step, the water content is preset to be 50 to 70% by weight, preferably 60% by weight, based on the total mass of the acesulfame k waste liquid.

Optionally, in the above method, in the first neutralization step and the second neutralization step, the preset conditions are: the reaction temperature is set to 105-120 ℃ and the reaction time is set to 2-10min.

Optionally, in the above method, in the step of recovering the product, solid-liquid separating the second aqueous phase to obtain a crude ammonium sulfate product and a residual liquid includes:

adjusting the pH value of the water phase to 6-8 by sulfuric acid;

adding an oxidant into the water phase with the pH value adjusted to perform oxidation reaction so as to reduce the content of residual ammonia nitrogen in the water phase, wherein the oxidant is hydrogen peroxide and the like; and

and (3) evaporating and crystallizing the water phase after the oxidation reaction is finished to obtain an ammonium sulfate crude product.

Optionally, in the above method, before the first neutralization step, the method further includes:

and (3) a solvent distillation step: and distilling the acesulfame potassium waste liquid to remove the solvent.

Optionally, the method further comprises:

and (3) recovering residual liquid: the raffinate produced in the product recovery step was mixed into acesulfame waste liquid.

In summary, the method comprises the steps of dividing liquid ammonia into two parts, adding the two parts into the acesulfame waste liquid step by step, reacting with sulfate and sulfuric acid in the waste liquid in a closed environment, recovering a large amount of amine in the first step, continuously adopting the liquid ammonia to react with unreacted sulfate and sulfuric acid after adjusting the concentration of the aqueous solution in the second step, thereby more effectively recovering the amine, and compared with other methods in the prior art, the method has the advantages of quick reaction, high triethylamine sulfate conversion rate and more thorough reaction; and greatly simplifies the processing technology of acesulfame potassium waste liquid, shortens the processing time and obviously improves the recovery efficiency of amine.

The foregoing description is only an overview of the present application, and is intended to be implemented in accordance with the teachings of the present application in order that the same may be more clearly understood and to make the same and other objects, features and advantages of the present application more readily apparent.

Detailed Description

Exemplary embodiments of the present application will be described in more detail below. It should be understood that the present application may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art.

The application aims at solving the problems of complex process, long time consumption and low amine recovery efficiency of the acesulfame waste liquid treatment process in the prior art, and provides a acesulfame waste liquid treatment method.

The treatment method of acesulfame potassium waste liquid provided by the application at least comprises the steps S110 to S150:

first neutralization step S110: adding first liquid ammonia into acesulfame waste liquid, and carrying out neutralization reaction in a closed reactor under preset conditions to obtain a first material.

In the present application, descriptions of "first" and "second" are presented, and the first "and" second "are used as distinguishing marks only, and are not meant in any way.

The acesulfame waste liquid is waste liquid produced by adopting a diketene-sulfur trioxide method to prepare acesulfame, and triethylamine is taken as a catalyst for example, and sulfate, sulfuric acid and impurity organic matters such as triethylamine, water and the like of the triethylamine exist in the acesulfame waste liquid.

In the process of preparing acesulfame, triethylamine exists as a catalyst, the amount of triethylamine is not consumed in the whole preparation process, and at the end of the reaction, the triethylamine is almost completely converted into triethylamine sulfate, and a very small amount of triethylamine remains in the reaction solution.

In the process of treating acesulfame waste liquid by using liquid ammonia, a plurality of equilibrium reaction processes exist in the whole reaction system, and the sulfate of the amine can not be thoroughly converted into the amine in the next reaction under the condition of high concentration of aqueous solution. The present application thus uses a two-step treatment and achieves an increase in the reaction rate by controlling the water content in the waste stream.

Firstly, putting acesulfame waste liquid into a closed reactor, dividing the total liquid ammonia which is expected to be added into two parts, adding the first liquid ammonia into the acesulfame waste liquid in a first neutralization step, and carrying out neutralization reaction under preset conditions to obtain a first material.

First separation step S120: and separating the first material into a first organic phase and a first aqueous phase, and evaporating the first aqueous phase until the water content reaches the preset water content to obtain a second material.

In the first neutralization reaction process, sulfate, sulfuric acid, impurity organic matters, water and the like of triethylamine mainly exist in the acesulfame waste liquid. The liquid ammonia reacts with the sulfate of triethylamine to generate triethylamine and ammonium sulfate, and reacts with sulfuric acid to generate ammonium sulfate, so that after the neutralization reaction is finished, an organic phase and an inorganic phase exist in the first material, wherein the organic phase mainly comprises solvent and triethylamine, the inorganic phase mainly comprises ammonium sulfate, sulfuric acid, triethylamine sulfate, water and a small amount of triethylamine dissolved in water, and the ammonium sulfate can be filtered.

The first material may be allowed to stand for delamination, thereby separating the organic and inorganic phases, denoted as first organic phase and first aqueous phase, and the first organic phase is temporarily left untreated.

In order to ensure that the subsequent liquid ammonia can react with triethylamine sulfate and sulfuric acid in the waste liquid quickly, firstly evaporating a first water phase, evaporating the water content to a preset water content, ending to obtain a second material, and taking the second material as a raw material for a second neutralization reaction to perform the next reaction.

The evaporation process may be any of those known in the art, such as atmospheric distillation, vacuum distillation, and the like.

The application is not limited with respect to the temperature of the evaporation of the water, and in some embodiments of the application, the acesulfame waste liquid may be evaporated in a boiling state in order to evaporate the water as soon as possible.

And under the condition that the water content reaches the preset water content, ending the water evaporation step. In the application, as a part of ions in the waste liquid are already consumed, the probability of combination between the ions is reduced due to the existence of a large amount of water, so that the reaction rate can be remarkably improved by evaporating the water; on the other hand, in the present application, both the liquid ammonia and the sulfate of triethylamine need to be dissolved in water, and therefore, the reaction requires water as a "carrier" for the neutralization reaction, and therefore, water must be present, water cannot be completely evaporated, and the lower the water content is, the better. Accordingly, the inventors have found through a number of experimental studies that when the water content reaches a certain preset water content, the reaction speed is better promoted, and in some embodiments of the present application, the preset water content is 50-70wt%, and in other embodiments of the present application, the preset water content is 60wt%, based on the total mass of the acesulfame waste liquid.

Second neutralization step S130: adding second liquid ammonia into the second material, and carrying out neutralization reaction in a closed reactor under preset conditions to obtain a third material;

and adding second liquid ammonia into the first material in the same way as the first neutralization step, wherein the second liquid ammonia is the rest of the predicted total liquid ammonia minus the first liquid ammonia. The neutralization reaction is likewise carried out in a closed reactor under preset conditions which may be identical to or different from, and preferably identical to, the preset conditions of the first neutralization step. Obtaining a third material after the reaction, wherein triethylamine sulfate is almost completely converted to generate triethylamine and ammonium sulfate, solvent, water and the like generated by sulfuric acid and liquid ammonia are mainly also present in the third material; wherein, most of triethylamine and solvent are remained in the organic phase, and the rest is remained in the water phase.

Second separation step S140: the third material is separated into a second organic phase and a second aqueous phase.

Including but not limited to, allowing the third material to stand for delamination, thereby separating the organic and inorganic phases, denoted as a second organic phase and a second aqueous phase.

And a product recovery step S150: recovering the first organic phase and the second organic phase as a crude triethylamine product; and carrying out solid-liquid separation on the second water phase to obtain an ammonium sulfate crude product and a residual liquid.

Almost all triethylamine remains in the first organic phase and the second organic phase, and the first organic phase and the second organic phase are mixed and recovered as a crude triethylamine product; in some embodiments of the present application, to obtain higher purity triethylamine, the obtained triethylamine may be distilled, specifically, the organic phase is cooled to 80-85 ℃ and then subjected to atmospheric distillation, and the raffinate is recovered as a crude triethylamine product.

For the treatment of the water phase, solid-liquid separation can be carried out on the second water phase to obtain an ammonium sulfate crude product and a residual liquid. The aqueous phase product mainly comprises ammonium sulfate and residual liquid, wherein a very small amount of triethylamine dissolved in the residual liquid exists in the residual liquid, and other impurities exist in the residual liquid, and the ammonium sulfate is solid, so that the aqueous phase is subjected to solid-liquid separation, and the crude product of the ammonium sulfate and the residual liquid can be obtained.

In some embodiments of the application, the residual liquid can be mixed into acesulfame waste liquid for recycling treatment so as to further improve the recovery rate of triethylamine. Since the reaction introduces little other reagents or reactants in the treatment method of the application, the particles in the waste liquid can be recovered basically completely, and the produced residual liquid can be recycled.

Optionally, in the above method, before the first neutralization step, the method further includes: and (3) a solvent distillation step: and distilling the acesulfame potassium waste liquid to remove the solvent. In some embodiments of the present application, in order to further increase the reaction rate, a solvent distillation step may be performed before the first neutralization step, i.e., the solvent is removed before the treatment, on the one hand to increase the reaction rate, and on the other hand the organic phase obtained after the completion of the waste liquid treatment is free of solvent, thereby reducing the trouble of post-treatment. Specifically, the acesulfame potassium waste liquid can be distilled to remove the solvent therein, and the distillation temperature can be determined according to the type of the solvent.

Acesulfame potassium waste liquid source and content of each component in acesulfame potassium waste liquid source

The acesulfame potassium waste liquid is generated by preparing acesulfame potassium by a diketene-sulfur trioxide method in the prior art in factories. The acesulfame waste liquid generally comprises 10-30wt% of sulfuric acid, 5-20wt% of triethylamine sulfate, 3-5wt% of impurity organic matters and the balance of water by taking the total mass of the acesulfame waste liquid as a reference.

The amount of liquid ammonia

The liquid ammonia is reacted with the sulfate radical of the acesulfame waste liquid, and is usually in excess in order to thoroughly convert the sulfate radical, and in some embodiments of the application, the molar ratio of the total amount of liquid ammonia to the sulfate radical in the acesulfame waste liquid is 2.5-4:1, that is, the molar ratio of the total amount of the first liquid ammonia and the second liquid ammonia to the sulfate radical in the acesulfame waste liquid is 2.5-4:1. The complete conversion of sulfate radical is ensured, after the neutralization reaction is finished, liquid ammonia is converted into ammonia, excessive unreacted ammonia exists in a reaction system, the excessive ammonia can be distilled, and specifically, after the first neutralization reaction is finished, the obtained first material is distilled to remove the excessive ammonia; after the second neutralization reaction is completed, the obtained second material is distilled to remove the excessive ammonia gas.

Ratio of the amount of the first liquid ammonia to the second liquid ammonia

The application is not limited to the ratio of the amounts of the first liquid ammonia to the second liquid ammonia, and most of the triethylamine is recovered in the first neutralization reaction, so that the amount of the first liquid ammonia is larger than the amount of the second liquid ammonia as a whole, and in particular, in some embodiments, the ratio of the amounts of the first liquid ammonia to the second liquid ammonia is 3-4:1-2.

Neutralization reaction conditions

In the present application, the neutralization reaction conditions are not limited, and in some embodiments of the present application, the preset conditions for the first neutralization reaction and the preset conditions for the second neutralization reaction may be the same, or may be different, and preferably the same. In some embodiments of the present application, in the first neutralization step and the second neutralization step, the preset conditions are: the reaction temperature is set to 105-120 ℃ and the reaction time is set to 2-10min.

The boiling state is favorable for the rapid reaction and improves the recovery rate of triethylamine under the condition that the reaction temperature is 105-120 ℃. In this state, the reaction is completed within 2 to 10 minutes without a long time.

In some embodiments of the application, in the product separation step, the aqueous phase may be treated by adjusting the pH of the second aqueous phase to a pH of 6-8 with sulfuric acid; adding an oxidant into the second water phase after the pH value is regulated to perform oxidation reaction so as to reduce the content of residual ammonia nitrogen in the second water phase; and evaporating and crystallizing the water phase after the oxidation reaction is finished to obtain an ammonium sulfate crude product.

Liquid ammonia and a small amount of solvent and impurity organic matters including a small amount of triethylamine, solvent, side reaction products and the like are also present in the second aqueous phase, and firstly, the pH value of the second aqueous phase is adjusted to 6-8 by adopting sulfuric acid, namely, the liquid ammonia is neutralized. And then adding an oxidant such as hydrogen peroxide and the like into the solution, so that the ammonia nitrogen content of the reaction solution is reduced, and inorganic ammonium is dissolved in water, and in the subsequent evaporation and crystallization process, the ammonium sulfate crystal with higher purity is obtained along with the evaporation of water.

Obtaining waste liquid: the acesulfame potassium is prepared by a diketene-sulfur trioxide method, and an aqueous phase and an organic phase are separated after a salifying step, wherein the aqueous phase is waste liquid to be treated in the application, the mass fraction of sulfuric acid in the waste liquid is 10-30%, the mass fraction of triethylamine sulfate is 5-20%, the mass fraction of impurity organic matters is 3-5%, and the balance is water, wherein triethylamine: sulfate radical molar ratio is 2:4-1. In each of the following examples or comparative examples, the acesulfame potassium waste liquid used was obtained by this method unless otherwise specified, and was obtained according to the specification if otherwise specified.

It should be noted that, the method for determining the content of triethylamine and sulfate radical in the acesulfame waste liquid can refer to the prior art or the national standard, such as GB/T23964 and GB/T23835.7, the application is not limited, and the following examples and comparative examples are not repeated.

Examples 1 to 5 and comparative examples 6 and 7

A first neutralization step: and (3) placing the acesulfame potassium waste liquid in a closed reactor, adding first liquid ammonia, sealing the closed reactor, and carrying out neutralization reaction under preset conditions to obtain a first material.

A first separation step: and separating the first material into a first organic phase and a first aqueous phase, and evaporating the first aqueous phase until the water content reaches the preset water content to obtain a second material.

And a second neutralization step: adding second liquid ammonia into the second material, and continuing to perform neutralization reaction in the closed reactor under preset conditions to obtain a third material.

A second separation step: the third material is separated into a second organic phase and a second aqueous phase.

The procedure of examples 1-5, comparative examples 6, 7 was identical, except for the setting of the preset conditions of the experiment, see in particular Table 1.

Table 1:

note that: the method for calculating the recovery rate of triethylamine comprises the following steps: the molar amount of triethylamine recovered was compared to the molar amount of triethylamine in the acesulfame waste liquid measured before treatment.

Comparative example 1

Neutralization reaction step: the acesulfame waste liquid is placed in a reaction kettle, pre-measured liquid ammonia is added into the reaction kettle at one time, the reaction kettle is closed, and the reaction kettle is maintained for a period of time at normal temperature, and specific reaction conditions and the mol ratio of the liquid ammonia to sulfate radical refer to the table 2, so as to obtain a second material.

And (3) a product separation step: after the neutralization reaction is finished, distilling the second material under normal pressure, and distilling out excessive ammonia gas and solvent remained in the second material; then separating the second material into an organic phase and an aqueous phase; wherein the organic phase is recovered as a crude triethylamine product; filtering the water phase to separate solid from liquid, and obtaining an ammonium sulfate crude product and a residual liquid.

Comparative example 2 (including comparative example 2A, comparative example 2B, comparative example 2C)

And (3) a water evaporation step: in the reaction kettle, the acesulfame potassium waste liquid is heated until the water content in the waste liquid reaches the preset water content, and in the comparative example 2, the specific water content is shown in the table 2, so as to obtain a first material.

Neutralization reaction step: the first material is placed in a reaction kettle, pre-measured liquid ammonia is added into the reaction kettle at one time, the reaction kettle is closed, the reaction kettle is maintained for a period of time at a preset reaction temperature, and specific reaction conditions and the molar ratio of the liquid ammonia to sulfate radical are shown in a table 2 to obtain the second material.

And (3) a product separation step: cooling to normal temperature (if needed) after the neutralization reaction is finished, distilling the second material under normal pressure, and distilling out excessive ammonia gas and solvent remained in the second material; then separating the second material into an organic phase and an aqueous phase; wherein the organic phase is recovered as a crude triethylamine product; filtering the water phase to separate solid from liquid, and obtaining an ammonium sulfate crude product and a residual liquid.

Table 2:

as can be seen from comparative example 1, the treatment of acesulfame waste liquid without evaporating water at normal temperature hardly achieved a comparatively ideal recovery effect (55%) of triethylamine even after a long reaction time (300 min).

As can be seen from examples 1 to 5 and comparative example 1B, the recovery rate of triethylamine can be significantly improved from 83% to 97% or more by dividing liquid ammonia into two steps.

As can be seen from comparison of comparative examples 1A, 1C and 1B, in the state where the reaction is boiling, the reaction rate can be greatly increased, so that the conversion of triethylamine sulfate in a short time (3 min) is significantly promoted.

Comparing examples 4 and 5 with examples 1 to 3, it can be seen that the reaction time can be greatly shortened by increasing the reaction temperature from 105 to 120 ℃ under the same conditions, the reaction time can be shortened to 3min, and the recovery rate of triethylamine is slightly increased.

As can be seen from examples 6 and 7, the recovery rate of triethylamine is not significantly changed at 140 and 160 ℃, which means that the reaction temperature is further increased at 120 ℃, which cannot bring about beneficial effects and waste of energy, thereby increasing the cost of waste liquid treatment.

In conclusion, the reaction time of the disposable liquid ammonia at normal temperature is long, and the conversion rate of reaction products is relatively low. Heating under the airtight condition, adding liquid ammonia in two steps, and has the advantages of high reaction speed, high conversion rate and capability of effectively recycling triethylamine. The recovery of triethylamine on the one hand shows higher economic value, and on the other hand, reduces the difficulty of subsequent treatment of organic waste; after triethylamine is separated, the residual waste liquid is continuously recycled, so that the final waste liquid discharge amount is reduced.

The foregoing is merely a specific embodiment of the application and other modifications and variations can be made by those skilled in the art in light of the above teachings. It is to be understood by persons skilled in the art that the foregoing detailed description is provided for the purpose of illustrating the application more fully, and that the scope of the application is defined by the appended claims.

Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features but not others included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the application and form different embodiments. For example, in the following claims, any of the claimed embodiments can be used in any combination.

Claims

1. The method for treating acesulfame waste liquid generated by preparing acesulfame by using a diketene-sulfur trioxide method is characterized by comprising the following steps:

a first neutralization step: adding first liquid ammonia into the acesulfame potassium waste liquid, and carrying out neutralization reaction in a closed reactor at the reaction temperature of 105-120 ℃ for 2-10min to obtain a first material;

a first separation step: separating the first material into a first organic phase and a first aqueous phase, evaporating the first aqueous phase until the water content reaches 50-70wt% based on the total mass of the acesulfame potassium waste liquid, and obtaining a second material;

and a second neutralization step: adding second liquid ammonia into the second material, and carrying out neutralization reaction in a closed reactor at the reaction temperature of 105-120 ℃ for 2-10min to obtain a third material;

2. The method of claim 1, wherein the acesulfame k waste comprises, based on the total mass of the acesulfame k waste: 10-30wt% of sulfuric acid, 5-20wt% of triethylamine sulfate and 3-5wt% of impurity organic matters.

3. The method according to claim 2, characterized in that the molar ratio of the total amount of the first liquid ammonia and the second liquid ammonia to sulfate radical in the acesulfame waste liquid is 2.5-4:1.

4. A method according to claim 3, wherein the ratio of the first liquid ammonia to the second liquid ammonia is 3-4:1-2.

5. The method of claim 3, wherein the first neutralizing step further comprises: after the neutralization reaction is finished, distilling the obtained first material to remove excessive ammonia;

the second neutralization step further includes: after the neutralization reaction is finished, the obtained second material is distilled to remove excessive ammonia gas.

6. The method according to claim 1, wherein in the first separation step, the preset water content is 60wt% based on the total mass of the acesulfame waste liquid.

7. The method of claim 1, wherein in the product recovery step, the subjecting the second aqueous phase to solid-liquid separation to obtain a crude ammonium sulfate product and a raffinate comprises:

adjusting the pH value of the water phase to 6-8 by sulfuric acid;

adding an oxidant into the water phase with the pH value adjusted to perform oxidation reaction; and

8. The method of claim 1, further comprising, prior to the first neutralizing step:

9. The method according to claim 1, wherein the method further comprises:

and (3) recovering residual liquid: mixing the raffinate produced in the product recovery step into the acesulfame waste liquid.