Extractant for extracting potassium ions from ammonium dihydrogen phosphate, method for preparing the same, and method for preparing battery-grade ammonium dihydrogen phosphate

Abstract

The application discloses an extractant for extracting potassium ions in ammonium dihydrogen phosphate, a preparation method of the extractant and a preparation method of battery-grade ammonium dihydrogen phosphate, and belongs to the technical field of lithium battery raw materials. The extractant for extracting potassium ions in ammonium dihydrogen phosphate is at least one of 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester, tributyl phosphate, dioctyl phosphate and methyl isobutyl ketone, glycerol, allyl alcohol and methanol, sulfonated kerosene, which are mixed and then subjected to saponification treatment. When battery-grade ammonium dihydrogen phosphate is prepared, the above extractant is added into an ammonium dihydrogen phosphate aqueous solution to remove potassium ions in the solution, and then the filtrate is concentrated, crystallized and dried to obtain the battery-grade ammonium dihydrogen phosphate. As can be seen from the above, the application prepares a reliable extractant for potassium ion impurities which are difficult to remove in ammonium phosphate fertilizer, and the potassium ions in agricultural ammonium dihydrogen phosphate can be removed by using the extractant to obtain the battery-grade ammonium dihydrogen phosphate, thereby providing a new method for removing potassium from phosphate fertilizer.

Description

Technical Field

[0001] This invention relates to the field of lithium battery raw material technology, and more specifically, to an extractant for extracting potassium ions from ammonium dihydrogen phosphate, its preparation method, and a method for preparing battery-grade ammonium dihydrogen phosphate. Background Technology

[0002] In recent years, with the ever-increasing production of phosphate fertilizers, significant pressure to reduce inventory has emerged, necessitating a reform of phosphate fertilizer products towards diversification and higher-value offerings. The rapid boom in the new energy industry has led to growing demand for lithium iron phosphate and lithium manganese iron phosphate materials, driving up the prices of upstream raw materials such as lithium and phosphorus. This not only increases production costs for enterprises but also hinders the rapid industrialization of the new energy sector. On one hand, there is overcapacity in phosphate fertilizer production, requiring inventory reduction; on the other hand, there is an urgent need for low-cost phosphorus sources in the new energy industry. However, potassium ion impurities in phosphate fertilizers are difficult to precipitate and effectively remove, making potassium ion impurity removal a key challenge in the transformation from monoammonium phosphate (MAP) to battery-grade ammonium dihydrogen phosphate.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects of the prior art by providing an extractant for extracting potassium ions from ammonium dihydrogen phosphate, its preparation method, and a method for preparing battery-grade ammonium dihydrogen phosphate.

[0005] The technical problem solved by this invention is achieved by the following technical solution.

[0006] This invention provides an extractant for extracting potassium ions from ammonium dihydrogen phosphate, which is obtained by mixing at least one of 2-ethylhexyl phosphate mono-2-ethylhexyl ester, tributyl phosphate, dioctyl phosphate and methyl isobutyl ketone with a solvent and a diluent, followed by saponification.

[0007] The present invention also provides a method for preparing the above-mentioned extractant for extracting potassium ions from ammonium dihydrogen phosphate, comprising: mixing at least one of 2-ethylhexyl phosphate mono-2-ethylhexyl ester, tributyl phosphate, dioctyl phosphate and methyl isobutyl ketone with a solvent and a diluent to obtain a mixture, and subjecting the mixture to saponification treatment to obtain the saponified extractant.

[0008] The present invention also provides a method for preparing battery-grade ammonium dihydrogen phosphate, which includes: using the above-mentioned extractant to remove potassium ions from the aqueous solution of ammonium dihydrogen phosphate.

[0009] The present invention has the following beneficial effects:

[0010] This invention provides an extractant for extracting potassium ions from ammonium dihydrogen phosphate, its preparation method, and a method for preparing battery-grade ammonium dihydrogen phosphate. The extractant provided by this invention is obtained by mixing at least one of 2-ethylhexyl phosphate mono-2-ethylhexyl ester, tributyl phosphate, dioctyl phosphate, and methyl isobutyl ketone with a solvent and a diluent, followed by saponification. 2-ethylhexyl phosphate mono-2-ethylhexyl ester, tributyl phosphate, dioctyl phosphate, and methyl isobutyl ketone are the main active components of the extractant. The solvent is used to improve the interfacial conditions between the organic and aqueous phases, and the diluent is used to reduce the cost of the extractant. During the extraction process, the extractant reacts with potassium ions in ammonium dihydrogen phosphate to form an extractant that enters the organic phase, while the ammonium dihydrogen phosphate remains in the aqueous phase. Through extraction and purification of ammonium dihydrogen phosphate, the potassium content in the raw material can meet the requirements for battery-grade ammonium dihydrogen phosphate, providing a new method for the production of battery-grade ammonium dihydrogen phosphate. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0012] The following describes in detail an extractant for extracting potassium ions from ammonium dihydrogen phosphate, its preparation method, and a method for preparing battery-grade ammonium dihydrogen phosphate, as provided in the embodiments of the present invention.

[0013] In a first aspect, embodiments of the present invention provide an extractant for extracting potassium ions from ammonium dihydrogen phosphate, which is obtained by mixing at least one of 2-ethylhexyl phosphate mono-2-ethylhexyl ester, tributyl phosphate, dioctyl phosphate and methyl isobutyl ketone with a solvent and a diluent, and then subjecting the mixture to saponification.

[0014] This invention provides an extractant for extracting potassium ions from agricultural ammonium dihydrogen phosphate. It is obtained by mixing at least one of 2-ethylhexyl phosphate mono-2-ethylhexyl ester, tributyl phosphate, dioctyl phosphate, and methyl isobutyl ketone with a solvent and a diluent, followed by saponification. The main active ingredient of the extractant includes at least one of 2-ethylhexyl phosphate mono-2-ethylhexyl ester, tributyl phosphate, dioctyl phosphate, and methyl isobutyl ketone. 2-ethylhexyl phosphate mono-2-ethylhexyl ester, tributyl phosphate, and dioctyl phosphate are phosphorus-type extractants, which are mainly extracted by the lone pairs of electrons on the oxygen atoms of these organophosphorus extractants coordinating with metal atoms to form O→Me bonds. The resulting extract is then extracted into the organic phase. Methyl isobutyl ketone is an oxygen-containing extractant. The electron cloud density of the coordinating oxygen atoms and the dipole moment of the molecule are the main factors determining its extraction ability. The main reason why oxygen-containing extractants can extract metals is that they can form complexes with metals and enter the organic phase for extraction. The main active ingredients mentioned above are mixed with solvents and diluents. The solvent can improve the interfacial conditions between the organic phase and the aqueous phase, while the diluent is mainly used to dilute the extractant and reduce the cost of the extractant.

[0015] In this embodiment of the invention, at least one of 2-ethylhexyl phosphate mono-2-ethylhexyl ester, tributyl phosphate, dioctyl phosphate, and methyl isobutyl ketone is mixed with a solvent and a diluent, and then subjected to saponification to obtain a saponified extractant. During the extraction process, the potassium ions extracted in the solution exchange with the ammonium ions in the extractant, and no hydrogen ions are generated, thus maintaining the optimal pH conditions of the extracted solution. Furthermore, no metal ions detrimental to extraction are generated throughout the process. Experimental results show that the above-mentioned extractant can effectively extract and remove potassium ions from ammonium dihydrogen phosphate, enabling the treated ammonium dihydrogen phosphate to meet battery-grade standards.

[0016] In an optional embodiment, the solvent includes at least one of glycerol, propylene alcohol, and methanol, and the diluent is selected from sulfonated kerosene;

[0017] Preferably, the amounts of each component in the extractant are as follows: 0-60 parts of 2-ethylhexyl phosphate mono-2-ethylhexyl ester, 15-30 parts of tributyl phosphate, 0-20 parts of dioctyl phosphate, 0-40 parts of methyl isobutyl ketone, 5-20 parts of glycerol, 10-50 parts of allyl alcohol, 5-30 parts of methanol, and 10-70 parts of sulfonated kerosene.

[0018] The extractant provided in this invention comprises at least one of 2-ethylhexyl phosphate mono-2-ethylhexyl ester, tributyl phosphate, dioctyl phosphate, and methyl isobutyl ketone. The main active components are mixed with a solvent and a diluent. In a preferred embodiment, glycerol, allyl alcohol, and methanol are selected as the main solvent system to improve the interfacial conditions between the organic and aqueous phases, making it easier for the extracted metal ions to be captured. This also improves the electron cloud of the extractant, enhancing its selectivity and extraction ability. Sulfonated kerosene is used as a diluent to reduce the cost of the extractant. The amount of each component in the extractant significantly affects its extraction ability because different proportions of the components result in different electron cloud distributions and steric hindrances, leading to varying impurity removal rates, which can be high or low. The extractant obtained through scientific formulation and optimized design in this invention can effectively extract potassium ions from ammonium dihydrogen phosphate. Using the extractant provided in this embodiment of the invention to perform multi-stage series continuous extraction of potassium ions in agricultural ammonium dihydrogen phosphate can maintain a high extraction efficiency. When processing the same concentration of potassium ions, the number of extraction stages can be reduced by using the saponified extractant.

[0019] Secondly, embodiments of the present invention also provide a method for preparing the above-mentioned extractant, which includes: mixing at least one of 2-ethylhexyl phosphate mono-2-ethylhexyl ester, tributyl phosphate, dioctyl phosphate and methyl isobutyl ketone with a solvent and a diluent to obtain a mixture, and subjecting the mixture to saponification treatment to obtain a saponified extractant.

[0020] In an optional embodiment, the solvent includes at least one of glycerol, propylene alcohol, and methanol, and the diluent is selected from sulfonated kerosene;

[0021] Preferably, the amounts of each component in the extractant are as follows: 0-60 parts of 2-ethylhexyl phosphate mono-2-ethylhexyl ester, 15-30 parts of tributyl phosphate, 0-20 parts of dioctyl phosphate, 0-40 parts of methyl isobutyl ketone, 5-20 parts of glycerol, 10-50 parts of allyl alcohol, 5-30 parts of methanol, and 10-70 parts of sulfonated kerosene.

[0022] In an optional embodiment, the preparation of the mixture includes: mixing at least one of 2-ethylhexyl phosphate mono-2-ethylhexyl ester, tributyl phosphate, dioctyl phosphate and methyl isobutyl ketone, and then stirring at room temperature for 1-12 hours to obtain the mixture.

[0023] In an optional embodiment, the saponification process includes: transferring the mixture to a refrigeration device, then adding ammonia water, and continuously stirring to obtain the saponified extractant;

[0024] Preferably, the temperature during the saponification process is maintained at 2-10℃;

[0025] Preferably, the volume ratio of ammonia water to the mixed solution is 1:(0.1-1), and the mass percentage concentration of ammonia water is 10%-25%.

[0026] Preferably, the stirring time is 6-24 hours.

[0027] The extractant provided above for extracting potassium ions from agricultural ammonium dihydrogen phosphate requires a saponification temperature maintained between 2-10℃. Excessive temperature during saponification leads to ammonia evaporation, polluting the environment and resulting in incomplete saponification. Insufficient temperature results in high energy consumption, hindering cost reduction.

[0028] Thirdly, embodiments of the present invention also provide a method for preparing battery-grade ammonium dihydrogen phosphate, which includes: using the above-mentioned extractant to remove potassium ions from an aqueous solution of ammonium dihydrogen phosphate.

[0029] The method for preparing battery-grade ammonium dihydrogen phosphate provided in this embodiment of the invention includes: removing potassium ions from an aqueous solution of ammonium dihydrogen phosphate by extraction with the above-mentioned extractant. In the extraction and purification method provided in this embodiment of the invention, at least one of the main active ingredients 2-ethylhexyl phosphate mono-2-ethylhexyl ester, tributyl phosphate, dioctyl phosphate, and methyl isobutyl ketone is mixed with a solvent and a diluent, followed by saponification treatment to obtain the final product. In the extraction and purification of ammonium dihydrogen phosphate, potassium ions in ammonium dihydrogen phosphate can react with the extractant to form an extractant that directly enters the organic phase of the extractant, while ammonium dihydrogen phosphate remains in the aqueous phase. Since no new organic solvent is added as an organic phase during the extraction process, but the extractant is directly extracted into the organic solvent of the extractant, this extraction method is simpler, faster, and more efficient, enabling large-scale industrial production. When using fertilizer-grade ammonium dihydrogen phosphate as raw material, the method described above provided in this embodiment of the invention can effectively remove potassium impurities from agricultural phosphate fertilizers, meeting the potassium impurity requirements of battery-grade ammonium dihydrogen phosphate, effectively reducing the raw material cost of lithium-ion batteries, and contributing to the healthier development of both industries.

[0030] In an optional embodiment, the ratio of the extractant to the aqueous solution of ammonium dihydrogen phosphate is controlled to be 1:(1-5);

[0031] Preferably, the extraction time is 12-24 hours.

[0032] In an optional embodiment, the preparation of the ammonium dihydrogen phosphate aqueous solution includes: dissolving ammonium dihydrogen phosphate in water at 20-60°C to obtain an ammonium dihydrogen phosphate aqueous solution;

[0033] Preferably, the amount of water used is 1-4 times the mass of ammonium dihydrogen phosphate;

[0034] Preferably, the ammonium dihydrogen phosphate is fertilizer-grade or industrial-grade.

[0035] This invention also provides a method for preparing battery-grade ammonium dihydrogen phosphate, comprising: removing potassium ions from an aqueous solution of ammonium dihydrogen phosphate using the aforementioned extractant. The phosphorus source can be fertilizer-grade or industrial-grade ammonium dihydrogen phosphate, and the state of the phosphorus source, such as powder, crystals, solution, or solid, is not limited. It is only necessary to dissolve the phosphorus source in water during extraction and purification to obtain a well-soluble aqueous solution. When extracting potassium ions from the phosphorus source using the extractant, the potassium ions react with the extractant to form an extractant that enters the organic solvent system, while the main components of the phosphorus source remain in the aqueous phase, thus achieving the extraction and purification of the phosphorus source. Currently, this invention has lower requirements for raw materials, a wider range of sources, and lower costs. The method of using an extractant to extract potassium ions from ammonium dihydrogen phosphate simplifies the entire extraction and impurity removal process, reduces costs, and is suitable for industrial production.

[0036] In an optional embodiment, the method further includes: filtering the potassium-removed ammonium dihydrogen phosphate aqueous solution, and then concentrating and crystallizing the resulting filtrate to obtain solid battery-grade ammonium dihydrogen phosphate.

[0037] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0038] This invention provides a method for preparing a potassium ion extractant for purifying ammonium dihydrogen phosphate, comprising the following steps:

[0039] (1) Ingredients: Mix 0-60 parts of 2-ethylhexyl phosphate mono-2-ethylhexyl ester, 15-30 parts of tributyl phosphate, 0-20 parts of dioctyl phosphate, 5-20 parts of glycerol, 10-50 parts of allyl alcohol, 5-30 parts of methanol, 0-40 parts of methyl isobutyl ketone and 10-70 parts of sulfonated kerosene, and stir at room temperature for 1-12 hours to obtain a mixture.

[0040] (2) Saponification: Transfer the mixture obtained in step (1) to a refrigeration device at 2-10℃, then add ammonia water at a volume ratio of 1:(0.1-1), and stir for 6-24 hours to obtain the saponified extractant.

[0041] (3) Extraction to remove potassium: Add 1-4 times the mass ratio of pure water to agricultural ammonium dihydrogen phosphate at 20-60℃, stir and dissolve, then add the saponified extractant from step (2). The ratio of extractant to ammonium dihydrogen phosphate solution is controlled at 1:(1-5). After extraction for 12-24 hours, potassium-removed ammonium dihydrogen phosphate solution (monoammonium phosphate solution) can be obtained. After the filtrate is concentrated and crystallized, solid battery-grade ammonium dihydrogen phosphate is obtained.

[0042] Example 1

[0043] A method for preparing battery-grade ammonium dihydrogen phosphate, the specific steps of which are as follows:

[0044] (1) Ingredients: Glycerin, tributyl phosphate, dioctyl phosphate, allyl alcohol, methanol, methyl isobutyl ketone and sulfonated kerosene are mixed together in volume ratios of 5%, 20%, 10%, 10%, 10%, 10%, 35%, and then stirred at room temperature for 6 hours to obtain a mixture.

[0045] (2) Saponification: The mixture obtained in step (1) is transferred to a refrigeration device at 5°C, and then ammonia water is added. The volume ratio of the mixture to ammonia water is controlled at 1:0.5, and the mixture is stirred for 12 hours to obtain the saponified extractant.

[0046] (3) Extraction to remove potassium: Add pure water at a mass ratio of 1 to agricultural ammonium dihydrogen phosphate at 60°C, stir and dissolve, then add the saponified extractant from step (2), with the ratio controlled at 1:5. After extraction for 12 hours, potassium-removed monoammonium phosphate solution can be obtained. After the filtrate is concentrated and crystallized, solid monoammonium phosphate is obtained. After further crushing and sealing, battery-grade ammonium dihydrogen phosphate can be obtained.

[0047] Example 2

[0048] A method for preparing battery-grade ammonium dihydrogen phosphate agent, the specific steps of which are as follows:

[0049] (1) Ingredients: 2-ethylhexyl phosphate mono-2-ethylhexyl ester, glycerol, tributyl phosphate, allyl alcohol, methanol, methyl isobutyl ketone and sulfonated kerosene are mixed together in volume ratios of 30%, 5%, 15%, 10%, 5%, 10% and 25%, and then stirred at room temperature for 6 hours to obtain a mixture.

[0050] (2) Saponification: The mixture obtained in step (1) is transferred to a refrigeration device at 5°C, and then ammonia water is added. The volume ratio of the mixture to ammonia water is controlled at 1:1, and the mixture is stirred for 12 hours to obtain the saponified extractant.

[0051] (3) Extraction to remove potassium: Add pure water at 1:1 mass ratio to agricultural ammonium dihydrogen phosphate at 60℃, stir and dissolve, then add the saponified extractant from step (2), with the ratio controlled at 1:4. After extraction for 12 hours, potassium-removed monoammonium phosphate solution can be obtained. After the filtrate is concentrated and crystallized, solid monoammonium phosphate is obtained. After further crushing and sealing, battery-grade ammonium dihydrogen phosphate can be obtained.

[0052] Example 3

[0053] A method for preparing battery-grade ammonium dihydrogen phosphate, the specific steps of which are as follows:

[0054] (1) Ingredients: 2-ethylhexyl phosphate mono-2-ethylhexyl ester, glycerol, tributyl phosphate, dioctyl phosphate, allyl alcohol, methanol and sulfonated kerosene are mixed together in volume ratios of 5%, 10%, 20%, 10%, 10%, 25% and 20%, and then stirred at room temperature for 8 hours to obtain a mixture.

[0055] (2) Saponification: The mixture obtained in step (1) is transferred to a refrigeration device at 5°C, and then ammonia is added. The volume ratio of the mixture to ammonia is controlled at 1:0.5, and the mixture is stirred for 12 hours to obtain the saponified extractant.

[0056] (3) Extraction to remove potassium: Add pure water at 1:1 mass ratio to agricultural ammonium dihydrogen phosphate at 60℃, stir and dissolve, then add the saponified extractant from step (2), with the ratio controlled at 1:4. After extraction for 12 hours, potassium-removed monoammonium phosphate solution can be obtained. After the filtrate is concentrated and crystallized, solid monoammonium phosphate is obtained. After further crushing and sealing, battery-grade ammonium dihydrogen phosphate can be obtained.

[0057] Comparative Example 1

[0058] A method for preparing battery-grade ammonium dihydrogen phosphate, the specific steps of which are as follows:

[0059] (1) Ingredients: Glycerin, tributyl phosphate, allyl alcohol, methanol and sulfonated kerosene are mixed together in volume ratios of 5%, 10%, 25%, 40% and 20%, and then stirred at room temperature for 8 hours to obtain a mixture.

[0060] (2) Saponification: The mixed solution obtained in step (1) is transferred to a refrigeration device at 5°C, and then ammonia water is added. The volume ratio of the mixed solution to ammonia water is controlled at 1:0.5, and the mixture is stirred for 12 hours to obtain the saponified extractant.

[0061] (3) Extraction to remove potassium: Add pure water at 60°C in an amount equal to the mass of agricultural ammonium dihydrogen phosphate, stir and dissolve, then add the saponified extractant from step (2), with the ratio controlled at 1:4. After extraction for 12 hours, potassium-removed monoammonium phosphate solution can be obtained. After the filtrate is concentrated and crystallized, solid monoammonium phosphate is obtained. After further crushing and sealing, battery-grade ammonium dihydrogen phosphate can be obtained.

[0062] Comparative Example 2

[0063] A method for preparing battery-grade ammonium dihydrogen phosphate, the specific steps of which are as follows:

[0064] (1) Ingredients: P204 and sulfonated kerosene are mixed together at a volume ratio of 40% and 60%, and then stirred at room temperature for 8 hours to obtain a mixture.

[0065] (2) Saponification: The mixed solution obtained in step (1) is transferred to a refrigeration device at 5°C, and then ammonia water is added. The volume ratio of the mixed solution to ammonia water is controlled at 1:0.5, and the mixture is stirred for 12 hours to obtain the saponified extractant.

[0066] (3) Extraction to remove potassium: Add pure water at 60°C in an amount equal to the mass of agricultural ammonium dihydrogen phosphate, stir and dissolve, then add the saponified extractant from step (2), with the ratio controlled at 1:4. After extraction for 12 hours, potassium-removed monoammonium phosphate solution can be obtained. After the filtrate is concentrated and crystallized, solid monoammonium phosphate is obtained. After further crushing and sealing, battery-grade ammonium dihydrogen phosphate can be obtained.

[0067] Test Results

[0068] The test results from Examples 1-3 and the comparative examples are shown in the table below:

[0069] raw materials 2930.48 \ Example 1 49.49 98.31％ Example 2 45.61 98.45％ Example 3 39.81 98.67％ Comparative Example 1 600.56 80.51％ Comparative Example 2 1230.79 42.01％

[0070] The test results above show that the potassium impurity content in the raw material agricultural ammonium dihydrogen phosphate is 2930.48 ppm. After extraction using the extractant prepared in the embodiments of this invention, the impurity removal rate is above 98%, and the potassium ions in the raw material agricultural ammonium dihydrogen phosphate are basically removed, ultimately obtaining battery-grade ammonium dihydrogen phosphate. However, in Comparative Example 1, changing the amount of each component in the extractant and reducing the composition of the extractant leads to a decrease in the electron cloud density of the extractant, reducing its attraction to potassium ions, thus decreasing the extraction capacity of the extractant and resulting in a significant decrease in the impurity removal rate. In Comparative Example 2, P2O4 was used alone. P2O4 was mixed with sulfonated kerosene to obtain a mixture, and then the mixture was saponified to obtain the extractant. This extractant could only achieve a potassium removal rate of 42.01% in the raw material, and the potassium impurity in the product did not meet the requirements for battery-grade monoammonium phosphate.

[0071] In summary, this invention provides an extractant for extracting potassium ions from ammonium dihydrogen phosphate, its preparation method, and a method for preparing battery-grade ammonium dihydrogen phosphate. The extractant provided by this invention is obtained by saponification of at least one of 2-ethylhexyl phosphate mono-2-ethylhexyl ester, tributyl phosphate, dioctyl phosphate, and methyl isobutyl ketone, mixed with glycerol, allyl alcohol, methanol, and sulfonated kerosene. In the preparation of battery-grade ammonium dihydrogen phosphate, the above-mentioned extractant is added to an aqueous solution of ammonium dihydrogen phosphate to remove potassium ions from the solution. After concentration, crystallization, and drying, the potassium content meets the requirements for battery-grade ammonium dihydrogen phosphate. After extraction with the extractant, the potassium removal rate in the raw material is >98%, and the potassium ions in the agricultural ammonium dihydrogen phosphate are essentially removed, ultimately yielding battery-grade ammonium dihydrogen phosphate. It is evident that the extractant provided in the embodiments of the present invention, and the method for producing battery-grade monoammonium phosphate from a low-cost fertilizer using the extractant, are reliable, have simple equipment, high production safety, energy-saving and consumption-reducing, and significantly reduce production costs, thereby generating better socio-economic value.

[0072] The above are merely preferred embodiments of the present invention and do not limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An extractant for extracting potassium ions from ammonium dihydrogen phosphate, characterized in that, It is obtained by mixing 0-60 parts of 2-ethylhexyl phosphate mono-2-ethylhexyl ester, 15-30 parts of tributyl phosphate, 0-20 parts of dioctyl phosphate, 0-40 parts of methyl isobutyl ketone, 5-20 parts of glycerol, 10-50 parts of allyl alcohol, 5-30 parts of methanol and 10-70 parts of sulfonated kerosene to obtain a mixture, and then saponifying the mixture with ammonia water at 2-10°C.

2. A method for preparing an extractant for extracting potassium ions from ammonium dihydrogen phosphate according to claim 1, characterized in that, It includes: A mixture of 0-60 parts of 2-ethylhexyl phosphate mono-2-ethylhexyl ester, 15-30 parts of tributyl phosphate, 0-20 parts of dioctyl phosphate, 0-40 parts of methyl isobutyl ketone, 5-20 parts of glycerol, 10-50 parts of allyl alcohol, 5-30 parts of methanol, and 10-70 parts of sulfonated kerosene is obtained. This mixture is then saponified to obtain a saponified extractant, wherein: The saponification process includes: transferring the mixture to a refrigeration device, then adding ammonia water, and continuously stirring to obtain the saponified extractant, with the temperature maintained at 2-10℃ during the saponification process.

3. The preparation method according to claim 2, characterized in that, The preparation of the mixture includes: mixing at least one of 2-ethylhexyl phosphate mono-2-ethylhexyl ester, tributyl phosphate, dioctyl phosphate and methyl isobutyl ketone, and stirring at room temperature for 1-12 hours to obtain the mixture.

4. The preparation method according to claim 2, characterized in that, The volume ratio of ammonia water to the mixture is 1:(0.1-1), and the mass percentage concentration of ammonia water is 10%-25%.

5. The preparation method according to claim 2, characterized in that, The stirring time is 6-24 hours.

6. A method for preparing battery-grade ammonium dihydrogen phosphate, characterized in that, It includes: Potassium ions in an aqueous solution of ammonium dihydrogen phosphate are removed by extraction using the extractant of claim 1 or the extractant prepared by any one of claims 2-5.

7. The preparation method according to claim 6, characterized in that, The ratio of the extractant to the aqueous solution of ammonium dihydrogen phosphate is controlled to be 1:(1-5).

8. The preparation method according to claim 7, characterized in that, The extraction time is 12-24 hours.

9. The preparation method according to claim 6, characterized in that, The preparation of ammonium dihydrogen phosphate aqueous solution includes: dissolving ammonium dihydrogen phosphate in water at 20-60℃ to obtain ammonium dihydrogen phosphate aqueous solution.

10. The preparation method according to claim 9, characterized in that, The amount of water used is 1-4 times the mass of the ammonium dihydrogen phosphate.

11. The preparation method according to claim 9, characterized in that, The ammonium dihydrogen phosphate is either fertilizer-grade or industrial-grade.

12. The preparation method according to claim 6, characterized in that, Also includes: The potassium-removed ammonium dihydrogen phosphate aqueous solution was filtered, and the resulting filtrate was concentrated and crystallized to obtain solid battery-grade ammonium dihydrogen phosphate.