CN116692795A - Potassium removal method for fertilizer grade monoammonium phosphate and application of product thereof - Google Patents

Abstract

The application provides a method for removing potassium from fertilizer-grade monoammonium phosphate and the application of the product thereof. The method for removing potassium comprises the following steps: dissolving fertilizer-grade monoammonium phosphate in water to obtain a solution of monoammonium phosphate; mixing fluorosilicic acid and /or add fluorosilicate to the monoammonium phosphate solution, adjust the pH value, react to obtain a mixed solution; separate the mixed solution from solid to liquid, and keep the clear liquid; dry the clear liquid to obtain purified monoammonium phosphate . This technical solution utilizes fluorosilicic acid and/or fluorosilicate to react with potassium ions to form potassium fluorosilicate precipitates, and separates the potassium fluorosilicate precipitates by solid-liquid separation to obtain monoammonium phosphate with low potassium content. The product has high purity, reasonable and effective preparation method, strong operability and is suitable for industrial production.

Description

Potassium removal method of fertilizer grade monoammonium phosphate and application of its products

technical field

The application belongs to the technical field of phosphate materials, and more specifically relates to a method for removing potassium from fertilizer-grade monoammonium phosphate and the application of its products.

Background technique

With the rapid development of lithium power batteries, the demand for lithium iron phosphate cathode materials in the new energy industry continues to increase, and monoammonium phosphate is one of the most important phosphorus sources for the synthesis of lithium iron phosphate cathode materials. As lithium power batteries have higher and higher requirements on the purity of raw materials, the content of each impurity is limited to a very low level. Fertilizer-grade monoammonium phosphate cannot meet the production requirements of positive electrode materials. This is because fertilizer-grade monoammonium phosphate raw materials contain some difficult-to-remove potassium.

An appropriate amount of potassium ions in the lithium iron phosphate positive electrode material can alleviate the formation of non-conductive compounds deposited on the surface of lithium metal, and prevent the transmission of potassium ions during the charging and discharging process of the battery, ultimately limiting the growth of lithium dendrites, thereby increasing the concentration of potassium ions. The cycle performance of the battery. However, excessive potassium content will reduce the battery capacity retention rate and easily lead to the instability of the lithium iron phosphate lattice, thereby shortening the battery life. Therefore, it is necessary to remove potassium from fertilizer-grade monoammonium phosphate.

Potassium ions have an ionic radius and physical properties very close to those of ammonium root ions. Therefore, it is difficult to not lose ammonium in phosphate fertilizers during the potassium removal process. There are few researches in the industry on the removal of potassium by monoammonium phosphate in phosphate fertilizer systems. The currently commonly used monoammonium phosphate potassium removal methods are:

1. Crystallization method, which is a low-energy, high-purity separation and purification method. After cooling the salt solution, put crystal seeds, and wait for the crystals to separate from the original solution to achieve purification. However, due to the similar properties of potassium ions and ammonium ions, similar crystal lattices will cover potassium in the crystallization process, so multiple crystallizations are often required to obtain monoammonium phosphate with higher purity, and its time cost and efficiency are not applicable. for large-scale industrial production.

2. Using the selective reaction of complexing agents to potassium ions, it seems feasible to further remove potassium chelates by electrodialysis, but because the complexing constant of potassium ions is small and unstable, except for expensive crown ethers, other Potassium chelates are prone to dissociation during electrodialysis.

Contents of the invention

Based on this, an object of the present application is to provide a method for removing potassium from fertilizer-grade monoammonium phosphate, to solve the difficulty in removing potassium from fertilizer-grade monoammonium phosphate in the prior art, which is not suitable for large-scale industrial applications question.

Another object of the present application is to provide the application of the purified monoammonium phosphate obtained by the potassium removal method of fertilizer grade monoammonium phosphate in the preparation of battery positive electrode materials, so as to reduce the production cost of positive electrode materials.

In order to achieve the above object, the technical scheme adopted by the application is:

In the first aspect, a method for removing potassium of fertilizer grade monoammonium phosphate is provided, comprising the following steps:

Dissolving fertilizer grade monoammonium phosphate in water to obtain monoammonium phosphate solution;

Adding fluorosilicic acid and/or fluorosilicate to the monoammonium phosphate solution, adjusting the pH value, and reacting to obtain a mixed solution;

The mixed solution is subjected to solid-liquid separation, and the clear liquid is retained;

The clear liquid is dried to obtain purified monoammonium phosphate.

Optionally, the solid-to-liquid ratio of fertilizer grade monoammonium phosphate to water is 1:3-1:5; and/or,

Fertilizer grade monoammonium phosphate with a potassium content of ≤5000ppm; and/or,

The potassium content in the purified monoammonium phosphate is ≤50ppm.

Optionally, the method of adding fluorosilicic acid and/or fluorosilicate to the monoammonium phosphate solution is slowly dropwise at a rate of 8mL/min-12mL/min; and/or,

The amount of fluosilicic acid and/or fluosilicate added is 3%-9% of the mass of the fertilizer grade monoammonium phosphate; and/or,

The step of adjusting the pH value includes; adding ammonia water to adjust the pH value to be greater than or equal to 4; and/or,

Drying includes spray drying.

Optionally, after the step of adjusting the pH value, the following steps are also included:

Add the inducer to the monoammonium phosphate solution under heating, and then treat it at low temperature.

Optionally, the amount of the inducer added is 0.02%-5% of the mass of fertilizer grade monoammonium phosphate; and/or,

The inducer includes at least one of polyacrylamide, ferric chloride, polyferric sulfate, small molecule alcohols, and hydrocarbon sulfonates; and/or,

The temperature of the heating condition is 40°C-50°C, and the time of the heating condition is 30min-40min; and/or,

The temperature of low temperature treatment is 1°C-5°C, and the time of low temperature treatment is 3h-5h.

After the step of low-temperature treatment, the following steps are also included: adding a dispersant to the monoammonium phosphate solution and stirring;

Preferably, the added amount of the dispersant is 0.05%-0.1% of the mass of fertilizer grade monoammonium phosphate;

Preferably, the dispersant includes polyethylene glycol (PEG-200, PEG-600), Triton X-100, sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB) , at least one of tributyl phosphate (TBP) and fatty alcohol polyoxyethylene ether (AEO).

Optionally, after the step of low temperature treatment or after the step of adding a dispersant and stirring, the following steps are also included:

Add barium compound and sulfate to the monoammonium phosphate solution at room temperature to react.

Optionally, the barium compound is added in an amount of 1%-5% of the mass of fertilizer-grade monoammonium phosphate; and/or,

The molar ratio of barium compound to sulfate is 0.95-1.1:0.45-0.55; and/or,

The barium compound comprises at least one of barium chloride, barium carbonate and barium hydroxide; and/or,

Sulfates include ammonium sulfate and/or ammonium bisulfate.

Optionally, before the step of adding the barium compound and sulfate, the following steps are also included: adding a precipitation aid to the monoammonium phosphate solution and stirring evenly;

Preferably, the addition amount of the precipitation aid is 0.06%-0.1% of the mass of fertilizer-grade monoammonium phosphate;

Preferably, the precipitation aid includes at least one of polyacrylic acid (PAA), acrylate, aminoethanol, tartaric acid (TA), dopamine (DOPA), and ethylenediaminetetraacetic acid (EDTA).

In the second aspect, the application of the purified monoammonium phosphate obtained by the potassium removal method of the above-mentioned fertilizer grade monoammonium phosphate in the preparation of battery cathode materials is provided

The beneficial effect of this application is:

The potassium removal method of fertilizer-grade monoammonium phosphate provided by the application utilizes fluorosilicic acid and/or fluorosilicate to react with potassium ions in fertilizer-grade monoammonium phosphate to form potassium fluorosilicate precipitation, and through solid-liquid separation The method separates the precipitation of potassium fluorosilicate to obtain the monoammonium phosphate solution with low potassium content; compared with the prior art, the potassium removal method of the fertilizer grade monoammonium phosphate of the present application utilizes the difference in chemical properties between potassium ions and ammonium ions, Potassium ions can react with fluorosilicic acid and/or fluorosilicate to form precipitates, ammonium ions do not react with fluorosilicate and/or fluorosilicate, remove potassium from fertilizer grade monoammonium phosphate, and purify monophosphate Ammonium, and the loss of ammonium is small, the preparation method is reasonable and effective, the operability is strong, and it is suitable for industrial production;

The potassium content of the purified monoammonium phosphate obtained by the fertilizer-grade monoammonium phosphate potassium removal method provided by the application is low, which can meet the production requirements of lithium-ion battery materials, and can be applied to the preparation of battery cathode materials.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved in this application clearer, the following examples further describe this application in detail. It should be understood that the specific embodiments described here are only used to explain the present application, and are not intended to limit the present application.

The potassium removal method of the fertilizer grade monoammonium phosphate of the embodiment of the application may further comprise the steps:

S1: Provide fertilizer-grade monoammonium phosphate, and dissolve fertilizer-grade monoammonium phosphate in water to obtain a monoammonium phosphate solution.

Fertilizer-grade monoammonium phosphate is a solid raw material, and it is made into a solution to prepare for subsequent reactions.

In some embodiments, the solid-to-liquid ratio of fertilizer-grade monoammonium phosphate to water is 1:3-1:5, and this dissolution ratio can obtain a better solution concentration, which is beneficial to subsequent potassium ions and fluosilicic acid and/or fluosilicic acid Salt reaction produces precipitation. If the concentration of monoammonium phosphate solution is too small, for example, the solid-liquid ratio of fertilizer grade monoammonium phosphate to water is less than 1:5, the content of potassium ions is low, and the reaction rate is low, which is not conducive to large-scale Remove potassium; if the concentration of monoammonium phosphate solution is too large, for example, the solid-to-liquid ratio of fertilizer grade monoammonium phosphate and water is greater than 1:3, and the concentration of monoammonium phosphate is close to the saturation concentration, and the concentration of monoammonium phosphate may be separated out in the reaction process crystals, loss of ammonium. Therefore, the solid-to-liquid ratio of fertilizer grade monoammonium phosphate to water can be selected as 1:3-1:5.

The potassium content of the fertilizer-grade monoammonium phosphate is ≤5000ppm, and the fertilizer-grade monoammonium phosphate can be treated with the potassium removal method of the present application, and a good potassium removal effect can be obtained.

S2: adding fluorosilicic acid and/or fluorosilicate to the monoammonium phosphate solution, adjusting the pH value, and performing a reaction to obtain a mixed solution.

Fluosilicic acid and/or fluorosilicate reacts with potassium ions in the monoammonium phosphate solution to form potassium fluorosilicate precipitation, and monoammonium phosphate does not react with fluorosilicate and/or fluorosilicate, so that it can pass solid Potassium is separated and removed by liquid separation.

In some embodiments, the method of adding fluorosilicic acid and/or fluorosilicate to the monoammonium phosphate solution is slowly dropwise, and the solution can be observed to become turbid obviously during the dropping process, and the dropping rate is 8mL/min-12mL/min , by controlling the drop rate, to control the concentration of fluorosilicic acid and/or fluorosilicate in the mixed solution and the reaction rate, to avoid the local concentration of the solution being too high, the resulting precipitate agglomerates, and the monoammonium phosphate is coated into the precipitated agglomerate In the group, the problem of loss of monoammonium phosphate is caused.

In some embodiments, the pH of the reaction solution is greater than or equal to 4, and by adjusting the pH of the solution, the precipitation of potassium fluorosilicate can be maximized.

Generally, fertilizer-grade monoammonium phosphate is an acidic mixture, so in some embodiments, the pH of the solution can be adjusted by adding ammonia water. Using ammonia water as a regulator can adjust the pH of the solution while avoiding the addition of other impurities.

S3: Separating the mixed solution into solid and liquid, and retaining the supernatant.

Most of the potassium is contained in the potassium fluorosilicate precipitate, and the monoammonium phosphate is in the clear liquid. The two can be separated by solid-liquid separation to achieve the purpose of purifying the monoammonium phosphate.

In some embodiments, after adding fluorosilicic acid and/or fluorosilicate, the reaction generates flocculent precipitates, and the precipitate particles are small, which is not conducive to solid-liquid separation treatment.

Therefore, in some embodiments, before the mixed liquid A is subjected to solid-liquid separation, the following steps are also included:

Under the conditions of heating and stirring, an inducer is added to the mixed solution to promote the precipitation of potassium fluorosilicate, and then treated at low temperature to obtain the mixed solution.

That is, after adding fluorosilicic acid and/or fluorosilicate, the reaction generates a precipitate, and then, under heating and stirring conditions, an inducer is added to the mixed solution to promote the precipitation of potassium fluorosilicate. After heating for a period of time, place the reaction system in a low temperature environment to continue the reaction. Adding an appropriate amount of inducer can induce the formation of potassium fluorosilicate crystal nuclei, thereby promoting precipitation. Heating can promote the completion of the reaction, and low temperature environment can reduce the concentration of fluorosilicate. The solubility of potassium in the solution makes the precipitation of potassium fluorosilicate complete.

It can be understood that the low temperature treatment is carried out under the condition of maintaining stirring, so as to avoid the agglomeration of the generated precipitates, and on the other hand, to avoid the scaling of the precipitates attached to the bottom of the reactor.

In some embodiments, the quality of the inducer is 0.02%-5% of the quality of fertilizer grade monoammonium phosphate, if the quality of adding inducer is too small, such as less than 0.02% of the quality of fertilizer grade monoammonium phosphate, the induction effect of the inducer is relatively low. If the amount of inducer added is too large, such as greater than 5% of the mass of fertilizer-grade monoammonium phosphate, and the amount of inducer introduced is large, it may affect the performance of the product, or cause the precipitation of monoammonium phosphate crystals And loss.

In some embodiments, the inducer includes at least one of polyacrylamide (PAM), ferric chloride, polyferric sulfate, small molecule alcohols, and hydrocarbon sulfonates, all of which inducers have a good ability to promote precipitation effect, and does not react with monoammonium phosphate.

In some embodiments, after the step of low temperature treatment, the following steps are also included:

Add the dispersant to the monoammonium phosphate solution and stir.

That is, after adding the inducer and reacting for a period of time under heating and stirring conditions, the temperature is lowered to continue the reaction, and then a small amount of dispersant, that is, a surfactant is added to the monoammonium phosphate solution. The interface energy between potassium fluorosilicate and the container reduces the surface adsorption of potassium fluorosilicate crystals, thereby preventing the initial deposition of scale and preventing the solid-liquid separation system and transmission pipeline from scaling and clogging.

In some embodiments, the mass of the dispersant is 0.05%-0.1% of the mass of fertilizer grade monoammonium phosphate.

In some embodiments, the dispersant includes polyethylene glycol (PEG-200, PEG-600), Triton X-100, sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide ( At least one of CTAB), tributyl phosphate (TBP), fatty alcohol polyoxyethylene ether (AEO).

In some embodiments, the temperature of the heating condition is 40°C-50°C, and the time of the heating condition is 30min-40min, which provides enough energy for the reaction of potassium ions and fluorosilicic acid and/or fluorosilicate to form precipitates, and promotes the reaction to the maximum. degree of response.

In some embodiments, the temperature of the low-temperature treatment is 1°C-5°C, and the time of the low-temperature treatment is 3h-5h. The solubility of potassium fluorosilicate in the solution is low in this temperature range, which is conducive to the complete precipitation of potassium fluorosilicate.

In some embodiments, after the step of low temperature treatment or after the step of adding a dispersant and stirring, the following steps are further included:

At room temperature, add barium compound and sulfate to the monoammonium phosphate solution to react.

Add appropriate amount of barium compound and sulfate before solid-liquid separation, barium compound and sulfate react to form barium sulfate precipitate, and co-precipitate with suspended potassium fluorosilicate to form large crystals to increase the filtration performance and separation effect of the precipitate. In addition, due to the dispersion and emulsification of the dispersant, the particle size of the potassium fluorosilicate particles becomes smaller, resulting in increased difficulty in filtration, so it is preferable to add the barium compound and sulfuric acid to the monoammonium phosphate solution after the step of adding the dispersant and stirring Salt.

In some embodiments, the quality of the barium compound is 1%-5% of the quality of fertilizer-grade monoammonium phosphate, and the amount of barium sulfate precipitation is controlled by controlling the amount of barium compound added to adjust the effect of potassium fluorosilicate-barium sulfate co-precipitation , Avoid excessive barium sulfate precipitation, increase the workload of solid-liquid separation, and reduce work efficiency.

In some embodiments, the molar ratio of barium compound to sulfate is (0.95-1.1):(0.45-0.55), according to the raw material containing 0.24%-0.25% sulfur impurity, and the reaction characteristics of barium ion and sulfate, barium and The molar ratio of sulfate radicals is 1:0.5, so preferably, the molar ratio of the input reactants is about 1:0.5.

In some embodiments, the barium compound includes at least one of barium chloride, barium carbonate, and barium hydroxide.

In some embodiments, the sulfate includes ammonium sulfate and/or ammonium bisulfate to reduce the introduction of other cations, and these sulfates can react with barium chloride, barium carbonate and barium hydroxide to produce barium sulfate precipitation.

In some embodiments, before the step of adding the barium compound and the sulfate, the following steps are further included:

Add the precipitation aid to the monoammonium phosphate solution and stir well.

Barium sulfate precipitation often has the disadvantages of being amorphous and easy to agglomerate during the formation process. In order to quickly form a uniform precipitation of potassium fluorosilicate-barium sulfate large particles, an appropriate amount of precipitation auxiliary agent is added to the mixed solution to promote the growth of barium sulfate crystals and improve the crystal shape. In order to improve the separation effect, a uniform spherical large particle precipitation is formed in the system.

In some embodiments, the mass of the precipitation aid is 0.06%-0.1% of the mass of fertilizer grade monoammonium phosphate.

In some embodiments, the precipitation aid includes at least one of polyacrylic acid (PAA), acrylate, aminoethanol, tartaric acid (TA), dopamine (DOPA), and ethylenediaminetetraacetic acid (EDTA). These precipitation aids It can promote the growth of barium sulfate crystals, and can be removed in the subsequent drying process to avoid affecting the purity and properties of monoammonium phosphate.

It can be understood that after solid-liquid separation treatment, in addition to obtaining clear liquid, solid slag is also obtained. The solid slag contains potassium fluorosilicate, which can be recycled and used in processes such as wood preservation and ceramics manufacturing. No solid waste is generated, no Environmental Pollution.

S4: drying the clear liquid to obtain purified monoammonium phosphate.

In some embodiments, the drying treatment includes spray drying, and the filtered monoammonium phosphate solution is spray-dried to obtain a solid product, and at the same time, the excess fluorosilicic acid in the solution is decomposed into hydrogen fluoride and silicon tetrafluoride gas under the high-temperature conditions of spray-drying. was removed.

In some embodiments, after the mixed liquid is subjected to solid-liquid separation, the obtained solid slag can be washed with a small amount of cold water to collect the monoammonium phosphate remaining on the solid slag, retain the liquid obtained by cleaning, and separate it from the solid-liquid The processed supernatants are mixed and dried together.

The potassium removal method of fertilizer-grade monoammonium phosphate provided in the embodiment of the present application utilizes fluorosilicic acid and/or fluorosilicate to react with potassium ions in fertilizer-grade monoammonium phosphate to form potassium fluorosilicate precipitation, and through solid-liquid The method of separation is to separate the precipitated potassium fluorosilicate to obtain a solution of monoammonium phosphate with low potassium content.

Compared with the prior art, the fertilizer-grade monoammonium phosphate potassium removal method in the embodiment of the present application utilizes the difference in chemical properties between potassium ions and ammonium ions, and potassium ions can react with fluorosilicate and/or fluorosilicate to form precipitates , Ammonium ions do not react with fluorosilicate and/or fluorosilicate, potassium is removed from fertilizer grade monoammonium phosphate, monoammonium phosphate is purified, and the loss of ammonium is small, the preparation method is reasonable and effective, and the process is simple, The method has strong operability, less medicament dosage, high selectivity for potassium precipitation, low overall cost and easy industrialization.

The method for removing potassium of the above-mentioned fertilizer grade monoammonium phosphate provided by the embodiments of the present application, the potassium content of the purified monoammonium phosphate obtained is lower than 50ppm, and the product purity reaches 99%. In the case of continuous feed production, monoammonium phosphate The yield can reach more than 99%, and the product performance is close to the raw material production requirements of lithium-ion battery materials. It can be applied to the preparation of positive electrode materials for batteries, such as lithium iron phosphate batteries, lithium manganese iron phosphate batteries, and lithium vanadium phosphate batteries. The positive electrode material of the battery.

The lithium iron phosphate positive electrode material made of the above-mentioned monoammonium phosphate has less impurities brought by the monoammonium phosphate, and the potassium content is suitable, which improves the lattice stability of the lithium iron phosphate positive electrode material and the cycle performance of the lithium ion battery.

The following is illustrated by multiple embodiments.

Example 1

The method for removing potassium of the fertilizer grade monoammonium phosphate of the present embodiment may further comprise the steps:

S1: Completely dissolve 15g of fertilizer grade monoammonium phosphate in deionized water at a solid-to-liquid ratio of 1:3 to obtain a monoammonium phosphate solution.

S2: Slowly drop 3% fluorosilicic acid and ammonium fluorosilicate into the monoammonium phosphate solution at a rate of 10mL/min, adjust the pH of the reaction solution to 4.0 with ammonia water while stirring, and form potassium fluorosilicate precipitation to obtain A mixture.

S3: Add 0.02% DNSK to the A mixture, stir at 50°C for 30min, then cool the reaction solution at 1°C for 3h, then add 0.05% AEO and stir to obtain the B mixture.

S4: Add 0.06% PAA into the B mixed solution, stir evenly, add 5% barium hydroxide and 0.5 times the molar mass of sulfate, and react at room temperature for 2 hours to obtain the C mixed solution.

S5: Filter and separate the mixture C, and rinse the filter cake with a small amount of cold water to obtain a clear liquid.

S6: After the clear liquid is spray-dried, purified monoammonium phosphate solid is obtained.

The composition analysis of the fertilizer grade monoammonium phosphate raw material and the purified monoammonium phosphate product in this embodiment is shown in Table 1.

Table 1

Example 2

The method for removing potassium of the fertilizer grade monoammonium phosphate of the present embodiment may further comprise the steps:

S1: Completely dissolve 15g of fertilizer grade monoammonium phosphate in deionized water at a solid-to-liquid ratio of 1:3 to obtain a monoammonium phosphate solution.

S2: Slowly drop 3% fluorosilicic acid/ammonium fluorosilicate into the monoammonium phosphate solution at a rate of 10mL/min, adjust the pH of the reaction solution to 4.0 with ammonia water while stirring, and form potassium fluorosilicate precipitation to obtain A Mixture.

S3: Add 5% ethanol to the mixed liquid A, stir at 50°C for 10 min, then cool the reaction liquid at 5°C for 5 h, then add 0.05% Triton X-100, stir well to obtain B Mixture.

S4: Add 0.06% EDTA to B mixed solution, stir evenly, add 3% barium carbonate and 0.5 times the molar mass of sulfate, and react at room temperature for 2 hours to obtain C mixed solution.

S5: Filter and separate the mixture C, and rinse the filter cake with a small amount of cold water to obtain a clear liquid.

S6: After the clear liquid is spray-dried, purified monoammonium phosphate solid is obtained.

The composition analysis of fertilizer grade monoammonium phosphate raw material and purified monoammonium phosphate product in this embodiment is shown in Table 2.

Table 2

Example 3

The method for removing potassium of the fertilizer grade monoammonium phosphate of the present embodiment may further comprise the steps:

S1: Completely dissolve 15g of fertilizer grade monoammonium phosphate in deionized water at a solid-to-liquid ratio of 1:4 to obtain a monoammonium phosphate solution.

S2: Add 5% ammonium fluorosilicate into the monoammonium phosphate solution. After the solid is dissolved, adjust the pH of the reaction solution to 4.0 with ammonia water while stirring, and form potassium fluorosilicate precipitation to obtain A mixed solution.

S3: Add 5% ethanol to the mixed solution A, stir at 50°C for 30 minutes, then cool the reaction solution at 1°C for 3 hours, then add 0.075% SDS and stir to obtain the mixed solution B.

S4: Add 0.06% PAA into the B mixed solution, stir evenly, add 5% barium hydroxide and 0.5 times the molar mass of sulfate, and react at room temperature for 2 hours to obtain the C mixed solution.

S5: Filter and separate the mixture C, and rinse the filter cake with a small amount of cold water to obtain a clear liquid.

S6: After the clear liquid is spray-dried, purified monoammonium phosphate solid is obtained.

The composition analysis of the fertilizer grade monoammonium phosphate raw material and the purified monoammonium phosphate product in this embodiment is shown in Table 3.

table 3

Example 4

The method for removing potassium of the fertilizer grade monoammonium phosphate of the present embodiment may further comprise the steps:

S1: Completely dissolve 15g of fertilizer grade monoammonium phosphate in deionized water at a solid-to-liquid ratio of 1:3 to obtain a monoammonium phosphate solution.

S2: Slowly drop 3% fluorosilicic acid into the monoammonium phosphate solution at a rate of 10 mL/min, adjust the pH of the reaction solution to 4.0 with ammonia water while stirring, and form potassium fluorosilicate precipitation to obtain A mixed solution.

S3: Add 0.02% naphthalenesulfonic acid into the mixed liquid A, stir at 50°C for 10 min, cool the reaction liquid at 5°C for 5 h, then add 0.05% Triton X-100, stir well, Obtain B mixture.

S4: Add 0.06% EDTA to B mixed solution, stir evenly, add 3% barium carbonate and 0.5 times the molar mass of sulfate, and react at room temperature for 2 hours to obtain C mixed solution.

S5: Filter and separate the mixture C, and rinse the filter cake with a small amount of cold water to obtain a clear liquid.

S6: After the clear liquid is spray-dried, purified monoammonium phosphate solid is obtained.

The composition analysis of fertilizer grade monoammonium phosphate raw material and purified monoammonium phosphate product in this example is shown in Table 4.

Table 4

Comparative example 1

The potassium removal method of the fertilizer grade monoammonium phosphate of this comparative example comprises the steps:

S1: Completely dissolve 15g of fertilizer grade monoammonium phosphate in deionized water at a solid-to-liquid ratio of 1:3 to obtain a monoammonium phosphate solution.

S2: Take 1% fluorosilicic acid/ammonium fluorosilicate and slowly drop it into the monoammonium phosphate solution, adjust the pH of the reaction solution to 4.0 with ammonia water while stirring, and form potassium fluorosilicate precipitation to obtain A mixed solution.

S3: Add 5% ethanol to the above solution, stir at 50°C for 10min, cool and precipitate the reaction solution at 1°C for 5h, add 0.05% Triton X-100, stir well to obtain B mixed solution .

S4: Add 0.06% EDTA to B mixed solution, stir evenly, add 3% barium carbonate and 0.5 times the molar mass of sulfate, and react at room temperature for 2 hours to obtain C mixed solution.

S5: Filter and separate the mixture C, and rinse the filter cake with a small amount of cold water to obtain a clear liquid.

S6: After the clear liquid is spray-dried, purified monoammonium phosphate solid is obtained.

The composition analysis of the monoammonium phosphate raw material and the purified monoammonium phosphate product in this comparative example 1 is shown in Table 5.

table 5

As can be seen from Table 1-4, in embodiment 1-4, remove the impurity potassium in the fertilizer grade monoammonium phosphate by utilizing the technical scheme of the application, can make the potassium content of the purified monoammonium phosphate all be lower than 50ppm, greatly The content of impurity potassium is reduced, and the purified monoammonium phosphate has high purity, which meets the requirement of being used as a raw material for preparing battery cathode materials. In addition, a small amount of calcium and magnesium impurities in the raw material are removed by reacting with hydrogen fluoride produced by the decomposition of fluorosilicic acid/ammonium fluorosilicate to form precipitates, and a small amount of sulfur impurities in the raw material are removed by forming barium sulfate precipitates with soluble barium salts , further improving the purity of the purified monoammonium phosphate.

As can be seen from the data in Table 5, with respect to Example 2, this comparative example keeps the reaction liquid-solid ratio, the reaction temperature constant, and the precipitating agent fluosilicic acid/ammonium fluosilicate is reduced to less than 1% of the raw material quality of monoammonium phosphate. %, the potassium precipitation reaction is insufficient, the degree of purification is reduced, and the residual potassium content is relatively large, which does not meet the raw material production requirements of battery cathode materials.

The above descriptions are only preferred embodiments of the application, and are not intended to limit the application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the application should be included in the protection scope of the application within.

Claims (10)

1. A method for removing potassium from fertilizer grade monoammonium phosphate is characterized by comprising the following steps: the method comprises the following steps:

dissolving fertilizer grade monoammonium phosphate into water to obtain monoammonium phosphate solution;

adding fluosilicic acid and/or fluosilicate into the monoammonium phosphate solution, adjusting the pH value, and reacting to obtain a mixed solution;

carrying out solid-liquid separation on the mixed solution, and keeping clear liquid;

and drying the clear liquid to obtain purified monoammonium phosphate.

2. The method for removing potassium from a fertilizer grade monoammonium phosphate according to claim 1, wherein: the solid-to-liquid ratio of the fertilizer grade monoammonium phosphate to water is 1:3-1:5; and/or the number of the groups of groups,

the potassium content in the fertilizer grade monoammonium phosphate is less than or equal to 5000ppm; and/or the number of the groups of groups,

the potassium content in the purified monoammonium phosphate is less than or equal to 50ppm.

3. The method for removing potassium from a fertilizer grade monoammonium phosphate according to claim 1, wherein: the fluosilicic acid and/or the fluosilicate are/is added into the monoammonium phosphate solution in a slow dropwise adding mode, and the dropwise adding speed is 8-12 mL/min; and/or the number of the groups of groups,

the addition amount of the fluosilicic acid and/or the fluosilicate is 3-9% of the mass of the fertilizer grade monoammonium phosphate; and/or the number of the groups of groups,

the step of adjusting the pH value comprises the following steps of; adding ammonia water, and adjusting the pH value to be more than or equal to 4; and/or the number of the groups of groups,

the drying treatment comprises spray drying.

4. The method for removing potassium from a fertilizer grade monoammonium phosphate according to claim 1, wherein: after the step of adjusting the pH value, the method further comprises the steps of:

an inducer is added to the monoammonium phosphate solution under heating, and then the solution is treated at a low temperature.

5. The method for removing potassium from a fertilizer grade monoammonium phosphate according to claim 4, wherein: the addition amount of the inducer is 0.02-5% of the mass of the fertilizer grade monoammonium phosphate; and/or the number of the groups of groups,

the inducer comprises at least one of polyacrylamide, ferric chloride, polymeric ferric sulfate, micromolecular alcohols and hydrocarbon sulphonates; and/or the number of the groups of groups,

the temperature of the heating condition is 40-50 ℃, and the time of the heating condition is 30-40 min; and/or the number of the groups of groups,

the temperature of the low-temperature treatment is 1-5 ℃, and the time of the low-temperature treatment is 3-5 h.

6. The method for removing potassium from a fertilizer grade monoammonium phosphate according to claim 4, wherein: after the step of low temperature treatment, the method further comprises the steps of: adding a dispersing agent into the monoammonium phosphate solution and stirring;

preferably, the addition amount of the dispersing agent is 0.05-0.1% of the mass of the fertilizer grade monoammonium phosphate;

preferably, the dispersing agent comprises at least one of polyethylene glycol, triton X-100, sodium dodecyl sulfate, cetyltrimethylammonium bromide, tributyl phosphate and fatty alcohol-polyoxyethylene ether.

7. The method for removing potassium from a fertilizer grade monoammonium phosphate according to claim 5 or 6, characterized by: after the step of low temperature treatment or after the step of adding a dispersant and stirring, the method further comprises the steps of:

and adding a barium compound and sulfate into the monoammonium phosphate solution at room temperature to perform a reaction.

8. The method for removing potassium from a fertilizer grade monoammonium phosphate according to claim 7, wherein: the addition amount of the barium compound is 1-5% of the mass of the fertilizer grade monoammonium phosphate; and/or the number of the groups of groups,

the molar ratio of the barium compound to the sulfate is (0.95-1.1): 0.45-0.55; and/or the number of the groups of groups,

the barium compound includes at least one of barium chloride, barium carbonate, and barium hydroxide; and/or the number of the groups of groups,

the sulfate comprises ammonium sulfate and/or ammonium bisulfate.

9. The method for removing potassium from a fertilizer grade monoammonium phosphate according to claim 7, wherein: before the step of adding the barium compound and the sulfate, the method further comprises the following steps: adding a precipitation auxiliary agent into the monoammonium phosphate solution and uniformly stirring;

preferably, the addition amount of the precipitation auxiliary agent is 0.06% -0.1% of the mass of the fertilizer grade monoammonium phosphate;

preferably, the precipitation aid includes at least one of polyacrylic acid, acrylic acid ester, amino ethanol, tartaric acid, dopamine and ethylenediamine tetraacetic acid.

10. Use of the purified monoammonium phosphate obtained by the potassium removal method of fertilizer grade monoammonium phosphate according to any one of claims 1-9 for the preparation of a battery positive electrode material.