CN-117795704-B - Ferric phosphate and preparation method and application thereof

CN117795704BCN 117795704 BCN117795704 BCN 117795704BCN-117795704-B

Abstract

The invention relates to ferric phosphate and a preparation method and application thereof, wherein the preparation method comprises the following steps of (1) mixing ammonium iron cyanide and a phosphorus source to obtain an iron-phosphorus mixed solution, (2) carrying out spray pyrolysis on the iron-phosphorus mixed solution obtained in the step (1) to obtain solid particles, and (3) crushing the solid particles obtained in the step (2) to obtain ferric phosphate. The iron phosphate provided by the disclosure has higher purity, tap density and specific surface area, and the preparation method can avoid using a pH value regulator and a surfactant, reduce the generation of byproducts and cleaning steps, greatly simplify the production process and have higher industrial application value.

Inventors

YU HAIJUN
LI AIXIA
XIE YINGHAO
LI CHANGDONG

Assignees

广东邦普循环科技有限公司
湖南邦普循环科技有限公司

Dates

Publication Date: 20260505
Application Date: 20231107

Claims (13)

1. A method for preparing ferric phosphate, comprising the following steps: (1) Mixing ammonium iron cyanide and a phosphorus source to obtain an iron-phosphorus mixed solution; (2) Carrying out spray pyrolysis on the iron-phosphorus mixed solution obtained in the step (1) to obtain solid particles; (3) Crushing the solid particles obtained in the step (2) to obtain ferric phosphate; the phosphorus source in step (1) comprises any one or a combination of at least two of phosphoric acid, monoammonium phosphate or diammonium phosphate.
2. The process according to claim 1, wherein the ammonium iron cyanide in step (1) is mixed in the form of an ammonium iron cyanide solution having a concentration of iron ions of 100 to 200g/L.
3. The preparation method according to claim 1, wherein the molar ratio of the iron element to the phosphorus element in the iron-phosphorus mixed solution in the step (1) is (0.98-1.02): 1.
4. The preparation method according to claim 1, wherein the carrier gas used for spray pyrolysis in the step (2) comprises air, and the flow rate of the carrier gas is 20-30L/min.
5. The preparation method according to claim 1, wherein the flow rate of the iron-phosphorus mixed solution in the spray pyrolysis is 1.5-1.8mL/min.
6. The preparation method according to claim 1, wherein the average particle diameter of atomized droplets of the iron-phosphorus mixed solution in the spray pyrolysis is 5-15 μm.
7. The method of claim 1, wherein the spray pyrolysis is at a temperature of 450-650 ℃.
8. The production process according to claim 1, wherein the solid particles of step (2) have an average particle diameter of 3 to 10 μm.
9. The preparation method of claim 1, wherein the smoke dust after spray pyrolysis in the step (2) is subjected to gas-solid separation to obtain solid powder and tail gas, the tail gas is absorbed by an absorbent to obtain an absorption liquid, the absorption liquid and ferric salt are mixed to obtain regenerated ammonium iron cyanide, and the regenerated ammonium iron cyanide is reused in the step (1) to prepare an iron-phosphorus mixed solution; The absorbent comprises an ammonium carbonate solution, wherein the mass concentration of the ammonium carbonate solution is 10-40%.
10. The method according to claim 1, wherein the crushing pressure in the step (3) is 0.2 to 0.6MPa.
11. The preparation method according to claim 1, wherein the preparation method comprises the steps of: (1) Mixing an iron ion concentration of 100-200g/L of an iron ammonium cyanide solution and a phosphorus source to obtain an iron phosphorus mixed solution, wherein the molar ratio of iron element to phosphorus element in the iron phosphorus mixed solution is (0.98-1.02): 1, and the phosphorus source comprises any one or a combination of at least two of phosphoric acid, monoammonium phosphate or diammonium phosphate; (2) Carrying out spray pyrolysis on the iron-phosphorus mixed solution obtained in the step (1) at a flow rate of 1.5-1.8mL/min by using air with a flow rate of 20-30L/min as carrier gas at a temperature of 450-650 ℃, wherein the average particle size of atomized liquid drops of the iron-phosphorus mixed solution in the spray pyrolysis is 5-15 mu m, and solid particles are obtained, and the average particle size of the solid particles is 3-10 mu m; carrying out gas-solid separation on smoke dust after spray pyrolysis to obtain solid powder and tail gas, absorbing the tail gas by adopting an ammonium carbonate solution with the mass concentration of 10-40% to obtain an absorption liquid, mixing the absorption liquid and ferric salt to obtain regenerated ammonium iron cyanide, and recycling the regenerated ammonium iron cyanide to prepare an iron-phosphorus mixed solution in the step (1); (3) Mixing the solid particles and the solid powder obtained in the step (2), and crushing under 0.2-0.6MPa to obtain the ferric phosphate.
12. An iron phosphate obtained by the process for producing an iron phosphate according to any one of claims 1 to 11.
13. Use of the iron phosphate of claim 12 to prepare a lithium iron phosphate positive electrode material.

Description

Ferric phosphate and preparation method and application thereof Technical Field The present disclosure relates to the technical field of lithium ion batteries, and in particular to an iron phosphate, a preparation method and an application thereof. Background In the fields of energy storage and new energy, the lithium iron phosphate battery is one of the most promising lithium ion batteries due to the advantages of good multiplying power performance, long cycle performance, safety, environmental protection and the like. Iron phosphate has received extensive attention and research as a precursor for lithium ion battery cathode material lithium iron phosphate. In the existing industrial production, the preparation process of the ferric phosphate mainly adopts purified ferrous sulfate or titanium white byproduct ferrous phosphate, ammonia water, monoammonium phosphate or diammonium phosphate and the like are added, and crystallization control is carried out by adopting a one-step aging method, so that the ferric phosphate product is finally obtained. However, the above process is easy to cause insufficient oxidation precipitation, large primary particles of ferric phosphate, small specific surface area and the like, and is not beneficial to the subsequent manufacturing and processing of lithium iron phosphate. For example, CN111115606a discloses a preparation method for preparing superfine spherical ferric phosphate by combining liquid phase precipitation and spray drying, the preparation method uses ferric salt solution and phosphoric acid as raw materials, and adopts ammonia water and phosphoric acid to adjust the pH value of the reaction, and although the preparation method can obtain superfine spherical ferric phosphate products, the adoption of ferric salt such as ferric sulfate leads to the production of by-product ammonium sulfate, and simultaneously, a large amount of sulfate radicals are easy to be adsorbed on the surface of ferric phosphate and difficult to be washed, so that the performance of lithium iron phosphate is affected by overhigh sulfur content. Therefore, the iron phosphate with good purity, specific surface area and tap density and the preparation method thereof are of great significance. Disclosure of Invention The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims. Aiming at the problems, the purpose of the present disclosure is to provide an iron phosphate, and a preparation method and application thereof, wherein compared with the prior art, the iron phosphate provided by the present disclosure has higher purity, tap density and specific surface area, and the preparation method avoids the use of a pH value regulator and a surfactant, reduces the generation of byproducts and cleaning steps, greatly simplifies the production process, and has higher industrial application value. To achieve the purpose, the present disclosure adopts the following technical scheme: in a first aspect, the present disclosure provides a method of preparing iron phosphate, the method comprising the steps of: (1) Mixing ammonium iron cyanide and a phosphorus source to obtain an iron-phosphorus mixed solution; (2) Carrying out spray pyrolysis on the iron-phosphorus mixed solution obtained in the step (1) to obtain solid particles; (3) Crushing the solid particles obtained in the step (2) to obtain ferric phosphate. The iron-phosphorus mixed solution prepared by the method does not need to adjust the pH value by acid or alkali, and is not easy to agglomerate. Further, the spray pyrolysis process is adopted, so that the dispersion form of the product can be controlled, the occurrence of agglomeration phenomenon is reduced, the particle size of the obtained ferric phosphate particles is smaller, the grinding is easy, the specific surface area and tap density are higher, and the morphology is regular. In addition, the ammonium iron cyanide and the phosphorus source only generate hydrogen cyanide gas and ammonia gas under the condition of spray pyrolysis, and no other byproducts are generated, so that the purity of the obtained ferric phosphate is higher, the step of repeated cleaning is avoided, the process flow is simplified, and the industrial application is facilitated. In one embodiment, the ammonium iron cyanide of step (1) is mixed in the form of an ammonium iron cyanide solution. In one embodiment, the concentration of ferric ions in the ammonium iron cyanide solution is 100-200g/L, and may be, for example, 100g/L, 110g/L, 120g/L, 130g/L, 140g/L, 150g/L, 160g/L, 170g/L, 180g/L, 190g/L, or 200g/L, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable. In one embodiment, the phosphorus source comprises any one or a combination of at least two of phosphoric acid, monoammonium phosphate, or diammonium phosphate. In the method, phosphoric acid, monoammonium phospha