CN-120191906-B - Widely-distributed water-soluble ammonium polyphosphate and preparation method thereof

Abstract

The invention discloses widely-distributed water-soluble ammonium polyphosphate and a preparation method thereof, and belongs to the technical field of compound fertilizers. When the APP is produced by utilizing the heat condensation reaction of water-soluble monoammonium phosphate and urea, water-soluble organic matters are introduced, the chain growth window period of the APP before solidification is prolonged, and the high water-soluble APP powder product with wide polymerization degree distribution is obtained, so that the sequence of the fertilizer-grade APP product is perfected. The monoammonium phosphate premelting combined APP cold-returning process has the advantages of shortening the operation time, greatly improving the productivity and solving the problem that the widely-distributed water-soluble product cannot be solidified. Organic matters combined with phosphorus in situ in the APP product not only improves the solubility, but also has synergistic potential of chelating trace elements in soil. The method for rapidly producing the wide-distribution water-soluble APP powder has simple process and is convenient for high-efficiency large-scale production.

Inventors

• YANG JINGXU
• ZHOU TIANYI
• LI XUE
• HE FUDUO
• WANG XINLONG

Assignees

• 四川大学

Dates

Publication Date

20260508

Application Date

20250506

Claims (4)

1. 1. The preparation method of the wide-distribution water-soluble ammonium polyphosphate is characterized by comprising the following steps of: s1, heating water-soluble monoammonium phosphate to be molten, adding sodium lignin sulfonate and urea into the molten water-soluble monoammonium phosphate, wherein the adding amount of the sodium lignin sulfonate is 10% of the mass of the water-soluble monoammonium phosphate, stirring and polymerizing at 185 ℃, adding urea once again after 15 min ℃, continuing stirring and polymerizing 25: 25 min to obtain a base material, and taking the total amount of the urea added as the basis of the N/P molar ratio of 1.86:1 in the system, wherein the adding mass ratio of the urea before and after two times is 3:4; S2, removing part of the base material 5min, and air-cooling to room temperature to obtain an additive; s3, adding the additive into the base material, uniformly stirring, then air-cooling to room temperature, crushing and screening to obtain the modified starch; the addition amount of the additive is 50% of the mass of the base material.
2. 2. The process according to claim 1, wherein the water-soluble monoammonium phosphate in S1 has a heat melting temperature of 190 ℃.
3. 3. The method of claim 1, wherein the stirring rate of the stirring polymerization in S1 is 30-40 rpm.
4. 4. A wide-distribution water-soluble ammonium polyphosphate, which is characterized by being prepared by the preparation method of any one of claims 1-3.

Description

Widely-distributed water-soluble ammonium polyphosphate and preparation method thereof Technical Field The invention belongs to the technical field of compound fertilizers, and particularly relates to a wide-distribution water-soluble ammonium polyphosphate and a preparation method thereof. Background The phosphate is heated to intermolecular dehydrate and can polymerize to form polyphosphate with P-O-P alternating structure. The structural general formula of ammonium polyphosphate (APP) can be written as (NH 4)n+2PnO3n+1. APP used for fertilizer is usually oligomer mixture with different chain lengths, APP with average polymerization degree n less than 20 belongs to water-soluble N, P compound fertilizer, and can desorb and chelate medium trace elements at the interface of soil solution and granules to promote the diffusion of P and medium trace elements, the soil fixation resistance, slow release property of gradual hydrolysis and solubilization property of medium trace elements in liquid formula fertilizer, the situation of fertilizer grade APP supply shortage keeps the market ton price of water-soluble APP above 8000 yuan (2025 years ago) for a long time, while even if expensive industrial monoammonium phosphate (MAP) is used as raw material, the cost of water-soluble APP (including depreciation) is not more than 5000 yuan/ton. Solid water-soluble APP is a main stream product of the prior fertilizer-grade APP because of low transportation cost, and industrial monoammonium phosphate is prepared by purifying and removing impurities through wet phosphoric acid in China, and then the APP is prepared by taking the industrial monoammonium phosphate and urea as raw materials. In addition, there is a method for preparing APP by phosphoric acid-urea condensation method (CN 105621381A), but the polymerization system needs a lot of time to evaporate water, the polymerization time is more than 2h, and the production strength is low. A method (CN 108002357A) for producing solid APP by phosphoric acid ammonification-returning granulation also appears in China, and is similar to the process of TVA in the United states, and has higher requirements on the concentration and purity of raw material phosphoric acid and high cost. Patent CN107176597a discloses a process for producing water-soluble APP in the form of powder particles using a belt conveyor polymerizer, which is similar to the process in another patent (CN 118771924B) for continuously producing water-soluble APP in solid form using a twin screw extruder, which is a feature and advantage of continuous production of solid APP using high viscosity solid materials, but the large amount of ammonia is lost during the conveying and polymerization process due to evaporation, and excessive urea is required to ensure solidification. At present, two types of APP brands of 18-58-0 and 14-65-0 are produced in China, but the high water-solubility APP solid products cannot be widely distributed in molecular weight (also called polymerization degree distribution) so as to solubilize more medium trace elements and meet the demands of different growth periods of crops on the hydrolysis of APP into orthophosphate. Therefore, it is necessary to invent a method for rapidly producing widely-distributed water-soluble APP powder to solve the above technical problems. Disclosure of Invention Aiming at the prior art, the invention provides wide-distribution water-soluble ammonium polyphosphate and a preparation method thereof, so as to solve the technical problem of narrow molecular weight distribution of the existing ammonium polyphosphate. In order to achieve the above purpose, the technical scheme adopted by the invention is that the preparation method of the wide-distribution water-soluble ammonium polyphosphate comprises the following steps: s1, heating water-soluble monoammonium phosphate to be molten, adding sodium lignin sulfonate and urea into the molten water-soluble monoammonium phosphate, wherein the adding amount of the sodium lignin sulfonate is 10% of the mass of the water-soluble monoammonium phosphate, stirring and polymerizing at 185 ℃, adding urea once again after 15 min ℃, continuing stirring and polymerizing 25: 25 min to obtain a base material, and taking the total amount of the urea added as the basis of the N/P molar ratio of 1.86:1 in the system, wherein the adding mass ratio of the urea before and after two times is 3:4; S2, cooling the base material to room temperature to obtain an additive; S3: adding additives into the base material, wherein the addition amount of the additives is 50% of the mass of the base material, uniformly stirring, then air-cooling to room temperature, crushing and screening. On the basis of the technical scheme, the invention can be improved as follows. Further, the heat melting temperature of the water-soluble monoammonium phosphate in S1 is 190 ℃. Further, the stirring rate of the stirring polymerization in S1 is 30-40 rpm. Further,