Method for producing functional diammonium phosphate by using white fertilizer
By utilizing low- to medium-grade phosphate rock and waste white fertilizer from filter presses to produce functional diammonium phosphate, the problem of insufficient phosphate rock resources has been solved, and the effects of energy conservation, consumption reduction, and soil improvement have been achieved, providing an economical and efficient method for the production of diammonium phosphate.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GANSU WENGFU CHEM
- Filing Date
- 2026-01-06
- Publication Date
- 2026-05-26
AI Technical Summary
Existing methods for producing diammonium phosphate require high-concentration phosphoric acid and high-purity phosphate rock, resulting in insufficient phosphate rock resources and difficulty in normal production. Furthermore, traditional methods fail to effectively utilize medium- and low-grade phosphate rock with high impurity content and waste white fertilizer from filter press production.
Medium- and low-grade phosphate rock containing functional additives and waste white fertilizer produced by pressure filtration are used. The mixture is neutralized with liquid ammonia in a tubular reactor to generate diammonium phosphate slurry with a neutralization degree of 1.4 to 1.45. The slurry is then subjected to secondary ammoniation in a granulator to finally form functional diammonium phosphate granules.
This method enables the production of diammonium phosphate from medium- and low-grade phosphate rock with high impurity content and waste white fertilizer, achieving the goal of energy conservation and consumption reduction. Furthermore, it improves soil quality through additives and enhances the effect of adding nutrients to crops.
Smart Images
Figure CN122079679A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of diammonium phosphate production technology, specifically to a method for producing functional diammonium phosphate using white fertilizer, and more particularly to a method for producing functional 60% diammonium phosphate using white fertilizer. Background Technology
[0002] The production of diammonium phosphate (DAP) in a tubular reactor typically involves metered phosphoric acid and liquid ammonia being pumped into a mixer located outside the granulator for neutralization. The resulting slurry is then sprayed through nozzles on the granulator's feed curtain for granulation. Simultaneously, a portion of the liquid ammonia is metered and fed into a secondary ammoniation distribution pipe within the granulator to further ammoniate the sprayed slurry, yielding DAP granules with a neutralization degree of approximately 1.8. Traditional DAP production methods require concentrated phosphoric acid (46%–48%) and stringent requirements for phosphoric acid impurities. However, with the rapid development of high-concentration phosphate compound fertilizers, phosphate rock resources are in short supply, hindering the normal operation of many enterprises. To meet the needs of national economic development, industrial production has consistently prioritized energy conservation and emission reduction through technological upgrades. Therefore, developing and promoting low-nutrient DAP products is crucial for further reducing product costs and improving economic efficiency. Summary of the Invention
[0003] The purpose of this invention is to provide a method for producing functional diammonium phosphate using white fertilizer. This method utilizes medium- and low-grade phosphate rock with high impurity content to produce ammonium phosphate, and can also utilize waste white fertilizer that cannot be processed during the filter press production process, thereby achieving the goal of energy saving and consumption reduction.
[0004] The technical solution adopted in this invention is as follows:
[0005] A method for producing functional diammonium phosphate using white fertilizer includes the following steps:
[0006] a. Waste white fertilizer from the filter press production process, containing 20%–22% P2O5 and 4%–5% N, is re-slurried in a slurry tank, with a re-slurry acid density of 1.58–1.65;
[0007] b. The re-pulped white fertilizer is transported to the tubular reactor reaction tank by the re-pulped white fertilizer transfer pump, and then fully stirred with phosphoric acid with a P2O5 content of 46% to 48% in the tubular reactor reaction tank to form mixed acid;
[0008] c. The mixed acid, delivered by the tubular reaction pump, and the liquid ammonia, delivered by the ammonia pump, undergo a neutralization reaction in the reaction chamber of the tubular reactor to generate a diammonium phosphate slurry with a neutralization degree of 1.4 to 1.45. After reacting fully in the reaction chamber for 1.0 to 3.0 seconds, the diammonium phosphate slurry is atomized and sprayed out through a specially designed diammonium phosphate slurry nozzle. At the same time, the functional additives delivered by the functional additive delivery pump and the atomized slurry are sent together to the return material curtain of the granulator for coating and granulation. Finally, the slurry sprayed by the tubular reactor is subjected to secondary ammoniation through the secondary ammoniation distribution pipe in the granulator, and finally functional diammonium phosphate granules are obtained.
[0009] d. The functional diammonium phosphate granules produced in step c are dried in a drying kiln;
[0010] e. Qualified functional diammonium phosphate granules are weighed and packaged after fine screening.
[0011] In step b, the pressure of phosphoric acid entering the reaction chamber is greater than 0.6 MPa; in step c, the pressure of liquid ammonia is 1.45–1.5 MPa; the operating temperature in the reaction chamber is 145–165 °C, and the operating pressure is 0.5 MPa; the neutralization degree of the generated diammonium phosphate particles is 1.8–1.85.
[0012] In step d, the exhaust gas temperature of the drying kiln is controlled to be 72℃~82℃.
[0013] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:
[0014] This invention provides a method for producing ammonium phosphate from medium- and low-grade phosphate rock with high impurity content; the use of waste white fertilizer that cannot be processed during the pressure filtration process as raw material achieves the purpose of energy saving and consumption reduction; by adding functional additives, not only are nutrients added to crops, but the soil is also improved. Attached Figure Description
[0015] Figure 1 This is a process flow diagram of the present invention; Detailed Implementation
[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific data in the embodiments. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.
[0017] Therefore, the following detailed description of embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0018] Example 1
[0019] like Figure 1 This embodiment provides a method for producing functional 60% diammonium phosphate using white fertilizer, including the following steps:
[0020] a. Waste white fertilizer containing 20%–22% P2O5 and 4%–5% N that cannot be processed during the filter press production process is re-slurried in a re-slurry tank to form re-slurry white fertilizer, with a re-slurry acid density of 1.58–1.65;
[0021] b. The re-pulped white fertilizer is transported to the tubular reactor reaction tank via a re-pulped white fertilizer transfer pump, and is thoroughly stirred with phosphoric acid with a P2O5 content of 46% to 48% in the specially designed tubular reactor reaction tank to form mixed acid; the pressure of phosphoric acid entering the reaction chamber is greater than 0.6 MPa;
[0022] c. The mixed acid, delivered by a tubular reaction pump, and liquid ammonia, delivered by an ammonia pump at a pressure of 1.45–1.5 MPa (absolute pressure), are neutralized in the reaction chamber of a tubular reactor. The operating temperature in the reaction chamber is 145–165℃, and the operating pressure is 0.5 MPa. After reacting fully in the reaction chamber for 1.0–3.0 seconds, a diammonium phosphate slurry with a neutralization degree of 1.4–1.45 is generated. The qualified diammonium phosphate slurry is atomized through a special nozzle and then coated and granulated together with functional additives delivered by a functional additive delivery pump on the return material curtain of the granulator.
[0023] d. The functional diammonium phosphate slurry sprayed into the granulator is coated and granulated, and then subjected to secondary ammoniation by the secondary ammoniation distribution pipe in the granulator to form functional diammonium phosphate particles.
[0024] e. After the functional diammonium phosphate granules are dried and dehydrated by the hot air in the hot air furnace in the drying kiln, the tail gas temperature of the drying kiln is controlled at 72℃~82℃; the resulting functional diammonium phosphate granules have a neutralization degree of 1.8~1.85, an available phosphorus P2O5 content of 43%~44%, a nitrogen content of 17%~17.5%, and a moisture content of 2.0%~2.5%.
[0025] f. After dehydration, the functional diammonium phosphate granules are screened by a screening device and then enter the packaging and metering device for metering and packaging.
[0026] In step c, the heat and vaporization pressure generated by the neutralization reaction of liquid ammonia and mixed acid in the special reaction chamber play a role in fully atomizing and propelling the slurry; the special nozzle in step c plays an important role in further atomizing the slurry after the neutralization reaction and adjusting the amount of slurry sprayed.
[0027] This embodiment provides a method for producing ammonium phosphate from medium- and low-grade phosphate rock with high impurity content. The raw material is waste white fertilizer that cannot be processed during the pressure filtration process, which achieves the purpose of energy saving and consumption reduction. By adding functional additives, not only are nutrients added to crops, but the soil is also improved.
Claims
1. A method for producing functional diammonium phosphate using white fertilizer, characterized in that, Includes the following steps, a. Waste white fertilizer from the filter press production process, containing 20%–22% P2O5 and 4%–5% N, is re-slurried in a slurry tank, with a re-slurry acid density of 1.58–1.65; b. The re-pulped white fertilizer is transported to the tubular reactor reaction tank by the re-pulped white fertilizer transfer pump, and then fully stirred with phosphoric acid with a P2O5 content of 46% to 48% in the tubular reactor reaction tank to form mixed acid; c. The mixed acid, delivered by the tubular reaction pump, and the liquid ammonia, delivered by the ammonia pump, undergo a neutralization reaction in the reaction chamber of the tubular reactor to generate a diammonium phosphate slurry with a neutralization degree of 1.4 to 1.
45. After reacting fully in the reaction chamber for 1.0 to 3.0 seconds, the diammonium phosphate slurry is atomized and sprayed out through a specially designed diammonium phosphate slurry nozzle. At the same time, the functional additives delivered by the functional additive delivery pump and the atomized slurry are sent together to the return material curtain of the granulator for coating and granulation. Finally, the slurry sprayed by the tubular reactor is subjected to secondary ammoniation through the secondary ammoniation distribution pipe in the granulator, and finally functional diammonium phosphate granules are obtained. d. The functional diammonium phosphate granules produced in step c are dried in a drying kiln; e. Qualified functional diammonium phosphate granules are weighed and packaged after fine screening.
2. The method for producing functional diammonium phosphate using white fertilizer according to claim 1, characterized in that: In step b, the pressure of phosphoric acid entering the reaction chamber is greater than 0.6 MPa; in step c, the pressure of liquid ammonia is 1.45–1.5 MPa; the operating temperature in the reaction chamber is 145–165 °C, and the operating pressure is 0.5 MPa; the neutralization degree of the generated diammonium phosphate particles is 1.8–1.
85.
3. The method for producing functional diammonium phosphate using white fertilizer according to claim 1, characterized in that: In step d, the exhaust gas temperature of the drying kiln is controlled to be 72℃~82℃.