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CN-116692795-B - Potassium removal method for fertilizer grade monoammonium phosphate and application of product thereof

CN116692795BCN 116692795 BCN116692795 BCN 116692795BCN-116692795-B

Abstract

The application provides a potassium removing method of fertilizer grade monoammonium phosphate and application of a product thereof, wherein the potassium removing method comprises the following steps of dissolving fertilizer grade monoammonium phosphate in water to obtain monoammonium phosphate solution; adding fluosilicic acid and/or fluosilicate into monoammonium phosphate solution, regulating pH value, reacting to obtain mixed solution, performing solid-liquid separation on the mixed solution, retaining clear solution, and drying the clear solution to obtain purified monoammonium phosphate. According to the technical scheme, fluosilicic acid and/or fluosilicate can react with potassium ions to generate potassium fluosilicate precipitate, and the potassium fluosilicate precipitate is separated by a solid-liquid separation method to obtain monoammonium phosphate with low potassium content, so that the product purity is high, the preparation method is reasonable and effective, the operability is strong, and the method is suitable for industrial production.

Inventors

  • YANG SIMIN
  • Zhang Yaotao
  • Li yineng
  • XU RONGYI
  • ZHANG SHENGXIANG
  • LIU CHENGWEI

Assignees

  • 佛山市德方纳米科技有限公司
  • 深圳市德方纳米科技股份有限公司

Dates

Publication Date
20260512
Application Date
20230531

Claims (8)

  1. 1. A method for removing potassium from monoammonium phosphate at a fertilizer level is characterized by comprising the following steps: Dissolving fertilizer grade monoammonium phosphate into water to obtain monoammonium phosphate solution; Adding fluosilicic acid and/or ammonium fluosilicate into the monoammonium phosphate solution, regulating the pH value, and reacting to obtain a mixed solution, wherein the addition amount of the fluosilicic acid and/or the ammonium fluosilicate is 3-9% of the mass of the fertilizer-grade monoammonium phosphate; Carrying out solid-liquid separation on the mixed solution, and keeping clear liquid; Drying the clear liquid to obtain purified monoammonium phosphate; The method comprises the following steps of adding an inducer into monoammonium phosphate solution under heating condition, and then carrying out low-temperature treatment, wherein the inducer comprises at least one of polyacrylamide, ferric chloride, polymeric ferric sulfate, micromolecular alcohols and hydrocarbon sulphonates, the temperature of the heating condition is 40-50 ℃, and the temperature of the low-temperature treatment is 1-5 ℃; after the step of low temperature treatment, further comprising the steps of adding a dispersant to the monoammonium phosphate solution and stirring; after the step of low temperature treatment or after the step of adding a dispersant and stirring, the method further comprises the steps of: Adding a barium compound and sulfate into the monoammonium phosphate solution at room temperature for reaction; Before the step of adding the barium compound and the sulfate, the method further comprises the step of adding a precipitation aid to the monoammonium phosphate solution and stirring the solution uniformly.
  2. 2. The method for removing potassium from monoammonium phosphate according to claim 1, characterized in that the solid-to-liquid ratio of monoammonium phosphate to water is 1:3-1:5, and/or, The potassium content in the fertilizer grade monoammonium phosphate is less than or equal to 5000ppm, and/or, The potassium content in the purified monoammonium phosphate is less than or equal to 50ppm.
  3. 3. The method for removing potassium from monoammonium phosphate according to claim 1, characterized in that the fluosilicic acid and/or ammonium fluosilicate is added into the monoammonium phosphate solution in a slow dropwise manner, the dropwise speed is 8-12 mL/min, and/or, The step of adjusting the pH value comprises adding ammonia water, adjusting the pH value to be more than or equal to 4, and/or, The drying treatment comprises spray drying.
  4. 4. The method for removing potassium from monoammonium phosphate according to claim 1, characterized in that the inducer is added in an amount of 0.02-5% by mass of the monoammonium phosphate and/or, The heating condition is for 30min-40min, and/or, The time of the low-temperature treatment is 3-5 h.
  5. 5. The method for removing potassium from a fertilizer grade monoammonium phosphate according to claim 1, wherein: the addition amount of the dispersing agent is 0.05-0.1% of the mass of the fertilizer grade monoammonium phosphate; The dispersing agent comprises at least one of polyethylene glycol, triton X-100, sodium dodecyl sulfate, cetyl trimethyl ammonium bromide, tributyl phosphate and fatty alcohol polyoxyethylene ether.
  6. 6. The method for removing potassium from monoammonium phosphate at a fertilizer level according to claim 1, wherein the barium compound is added in an amount of 1-5% by mass of the monoammonium phosphate at a fertilizer level and/or, The molar ratio of the barium compound to the 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, The sulfate comprises ammonium sulfate and/or ammonium bisulfate.
  7. 7. The method for removing potassium from a fertilizer grade monoammonium phosphate according to claim 1, wherein: The addition amount of the precipitation auxiliary agent is 0.06-0.1% of the mass of the fertilizer grade monoammonium phosphate; the precipitation aid comprises at least one of polyacrylic acid, acrylic acid ester, amino ethanol, tartaric acid, dopamine and ethylenediamine tetraacetic acid.
  8. 8. Use of the purified monoammonium phosphate obtained by the potassium removal method of fertilizer grade monoammonium phosphate according to any one of claims 1-7 for the preparation of a battery positive electrode material.

Description

Potassium removal method for fertilizer grade monoammonium phosphate and application of product thereof Technical Field The application belongs to the technical field of phosphate materials, and particularly relates to a method for removing potassium from fertilizer-grade monoammonium phosphate and application of a product thereof. Background With the development of lithium power batteries, the demand of new energy industries for lithium iron phosphate positive electrode materials is continuously increasing, and monoammonium phosphate is one of the most important phosphorus sources for synthesizing the lithium iron phosphate positive electrode materials. Since the higher the purity requirements of the lithium power battery on the raw materials, the lower the content of each impurity is limited, the fertilizer grade monoammonium phosphate cannot meet the production requirements of the cathode material because the fertilizer grade monoammonium phosphate raw materials contain part of potassium which is difficult to remove. The lithium iron phosphate anode material contains a proper amount of potassium ions, so that the formation of non-conductive compounds deposited on the surface of metal lithium can be relieved, the transmission of the potassium ions is prevented in the charge and discharge process of the battery, and the growth of lithium dendrites is finally limited, thereby improving the cycle performance of the potassium ion battery. However, too high a potassium content reduces battery capacity retention and tends to cause instability of the lithium iron phosphate lattice, thereby shortening battery life, and thus it is necessary to remove potassium from the monoammonium phosphate of fertilizer grade. The potassium ions have the ion radius and physical properties very close to those of ammonium ions, so that the difficulty of not losing ammonium in the phosphate fertilizer in the potassium removal process is high, and the research of the industry on monoammonium phosphate potassium removal of a phosphate fertilizer system is less. The method for removing potassium from monoammonium phosphate commonly used at present comprises the following steps: 1. the crystallization method is a separation and purification method with low energy consumption and high purity, and is characterized in that after a salt solution is cooled, seed crystals are placed in the salt solution, and crystals are waited to separate from an original solution, so that the purification is realized. However, due to the similar nature of potassium ions and ammonium ions, similar crystal lattices will encapsulate potassium during crystallization, and thus multiple crystallization is often required to obtain monoammonium phosphate of higher purity, and the time cost and efficiency are not suitable for large-scale industrial production. 2. The selective reaction of the complexing agent on potassium ions and further removal of potassium chelate by electrodialysis seems feasible, but other potassium chelates are easily dissociated in the electrodialysis process except for expensive crown ether due to the small complexing constant of potassium ions and instability. Disclosure of Invention Based on the above, an object of the present application is to provide a method for removing potassium from monoammonium phosphate at a fertilizer level, so as to solve the technical problems of the prior art that the method for removing potassium from monoammonium phosphate at a fertilizer level is difficult and is not suitable for large-scale industrial application. The application also aims to provide an application of the purified monoammonium phosphate obtained by the potassium removal method of the fertilizer-grade monoammonium phosphate in preparing a battery positive electrode material, so as to reduce the production cost of the positive electrode material. In order to achieve the above purpose, the application adopts the following technical scheme: In a first aspect, a method for removing potassium from fertilizer grade monoammonium phosphate is provided, comprising the steps of: Dissolving fertilizer grade monoammonium phosphate into water to obtain monoammonium phosphate solution; Adding fluosilicic acid and/or fluosilicate into monoammonium phosphate solution, adjusting the pH value, and reacting to obtain 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. Optionally, the solid to liquid ratio of fertilizer grade monoammonium phosphate to water is 1:3-1:5, and/or, The potassium content of the fertilizer grade monoammonium phosphate is less than or equal to 5000ppm and/or, The potassium content in the purified monoammonium phosphate is less than or equal to 50ppm. Optionally, the fluorosilicic acid and/or fluorosilicate is added to the monoammonium phosphate solution in a slow dropwise manner at an acceleration of 8mL/min to 12mL