A method for preparing a sulfur phosphorus urea process co-production compound fertilizer

Abstract

The application discloses a preparation method of compound fertilizer by sulfur phosphorus urea process, and belongs to the technical field of compound fertilizer.The preparation method of the compound fertilizer by the sulfur phosphorus urea process comprises the following steps: first, mixing and reacting equal-molar-ratio phosphoric acid and urea, inputting the mixture into a buffer tank and then into a tubular reactor, and inputting concentrated sulfuric acid into the tubular reactor; then, spraying the mixed slurry on a granulator bed while inputting ammonia gas, and sequentially performing processes such as drying, screening, cooling, film coating and packaging to obtain urea phosphate compound fertilizer.The process integrates the synthesis of urea phosphate, acidification reaction and neutralization granulation in a continuous flow, shortens the process flow, improves the production efficiency, increases the compound fertilizer yield by more than 10%, and stably supplies nutrients for a long time.Through the preparation method, the granulation effect is more stable, the product has a compressive strength of more than 30N, is not easy to cake, and the chemical reaction heat is used to drive the process, so that energy consumption is significantly reduced.

Description

Technical Field

[0001] This invention belongs to the field of compound fertilizer technology, specifically relating to a method for preparing compound fertilizer using a thiophosphorus-urea process. Background Technology

[0002] Thiophanate, a compound containing multiple nutrients such as sulfur, phosphorus, and nitrogen, has received considerable attention in the field of new fertilizer research and development in recent years. Drum granulation is a common compound fertilizer granulation process with many advantages, such as uniform granulation, low return material, high production capacity, easy drying, energy saving and consumption reduction, wide raw material adaptability, and simple operation. However, drum granulation also has some disadvantages, such as: 1. High requirements for process condition control: Improper process condition control may lead to increased return material, affecting production efficiency; 2. Relatively low particle strength: Sometimes, the particles produced by drum granulation may not be strong enough, easily breaking or even pulverizing during handling and storage.

[0003] To address the above deficiencies and improve the appearance quality and yield of thiophosphazone fertilizer, a method for preparing thiophosphazone is provided. This method effectively mobilizes the mutual reactions between various raw materials, combines moisture control in the drying process, improves the compressive strength of the granules, and enhances product yield and quality. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by providing a method for preparing compound fertilizer produced by the co-production of thiophosphorus urea process. It utilizes the viscosity of urea phosphate, the heat of dilution of urea phosphate and sulfuric acid, and the heat of reaction of urea phosphate, sulfuric acid and gaseous ammonia, respectively, to effectively mobilize the mutual reactions between various raw materials. Combined with the control of moisture in the drying process, it improves the compressive strength of the granules and increases the yield and quality of the product.

[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows: A method for preparing compound fertilizer by co-production of thiophosphorus urea process includes the following steps: (1) First, phosphoric acid and urea with a molar ratio of 1:1 are stirred at a constant temperature between 70-90℃ for 1 hour; (2) The prepared urea phosphate slurry is transported to the buffer tank through a pipeline and then pumped to the tubular reactor. At the same time, urea phosphate and sulfuric acid are simultaneously introduced into the tubular reactor at a molar ratio of 1:1. (3) The heat generated by the reaction of sulfuric acid and urea phosphate is used to further heat the mixed slurry to 90-110℃; (4) Spray the mixed slurry onto the material bed inside the granulator for granulation, and at the same time introduce ammonia gas into the material bed for neutralization reaction; (5) After going through drying, screening, cooling, coating and packaging processes, a qualified urea phosphate compound fertilizer product is finally obtained. With the addition of external materials, any nitrogen, phosphorus and potassium ratio can be carried out.

[0006] Furthermore, the sulfuric acid in step (2) is 98% concentrated sulfuric acid.

[0007] Furthermore, the phosphoric acid concentration in step (1) is 45%.

[0008] Furthermore, in step (4), the amount of ammonia introduced is added according to a molar ratio of N:P of 1:3.

[0009] Furthermore, the nitrogen, phosphorus, and potassium content of the thiophosphorus-urea compound fertilizer product is 15-15-15 or 12-18-1.

[0010] Beneficial effects The process of this invention integrates the synthesis, acidification reaction and neutralization granulation of thiophosphazone into a continuous process. The slurry is sprayed directly from the tubular reactor to the granulator, eliminating the need for intermediate cooling, storage and transportation, shortening the process flow, improving production efficiency and increasing the yield of compound fertilizer by more than 10%.

[0011] The preparation method of this invention achieves more stable granulation control, with the product compressive strength reaching over 30N. The granules are round and full, and are not prone to clumping. Furthermore, the process is driven by the heat of chemical reaction, resulting in significant energy savings and reduced consumption.

[0012] The product boasts high compressive strength and a long-lasting, stable nutrient supply. Some of the phosphorus it contains is highly active, water-soluble phosphorus, ensuring comprehensive and thorough crop absorption, thus enhancing drought resistance and increasing yield. By adjusting the solid raw materials, it guarantees the presence of multiple nutrients, promoting a balanced nutrient supply and facilitating the absorption of various micronutrients by crops, resulting in high-quality and high-yield crop growth. Detailed Implementation

[0013] The technical solution of the present invention will be further described below with reference to specific embodiments, but it is not limited thereto.

[0014] Example 1 A method for preparing compound fertilizer by co-production of thiophosphorus urea process includes the following steps: (1) First, phosphoric acid and urea with a molar ratio of 1:1 are stirred at a constant temperature between 70-90℃ for 1 hour; (2) The prepared urea phosphate slurry is transported to the buffer tank through a pipeline and then pumped to the tubular reactor. At the same time, urea phosphate and sulfuric acid are simultaneously introduced into the tubular reactor at a molar ratio of 1:1. (3) The heat generated by the reaction of sulfuric acid and urea phosphate is used to further heat the mixed slurry; (4) Spray the mixed slurry onto the material bed inside the granulator for granulation, and at the same time introduce ammonia gas into the material bed for neutralization reaction; (5) After sequentially undergoing drying, sieving, cooling, coating, and packaging processes, a qualified urea phosphate compound fertilizer product is finally obtained. Combined with external materials, the prepared sulfur-phosphorus-urea compound fertilizer product has a nitrogen, phosphorus, and potassium content of 15-15-15.

[0015] In step (2), the sulfuric acid is 98% concentrated sulfuric acid.

[0016] The phosphoric acid concentration in step (1) is 45%.

[0017] In step (4), the amount of ammonia introduced is added according to a molar ratio of N:P of 1:3.

[0018] Comparative Example 1 Compared with Example 1, except that the amount of ammonia gas introduced is added according to the molar ratio of N:P of 1:1, all other raw materials and steps are the same as in Example 1.

[0019] Comparative Example 2 Compared with Example 1, except that the amount of ammonia gas introduced is added according to the molar ratio of N:P of 1:4, all other raw materials and steps are the same as in Example 1.

[0020] Performance testing Product compressive strength test (1) Sampling: Use tweezers to randomly select a certain number (usually 10-20) of fertilizer granules from the dried and cooled sample and place them on a clean and flat weighing paper.

[0021] (2) Place the selected fertilizer granules one by one on the test platform of the compressive strength tester. Ensure that the granules are placed stably and in good contact with the test platform. Try to make the force direction of the granules perpendicular to their maximum cross-section to ensure the accuracy of the test results.

[0022] (3) Apply pressure: Start the compressive strength tester and apply pressure to the fertilizer granules at a specified rate (generally 10 mm / min - 50 mm / min) until the granules break. During the pressure application process, the instrument will automatically record the maximum pressure value that causes the granules to break.

[0023] (4) Repeat the operation: Test the remaining fertilizer particles one by one according to the above method and record the compressive strength value of each particle.

[0024] (5) Calculate the average value of the compressive strength of all fertilizer particles tested. This average value is the compressive strength test result of this batch of compound fertilizer.

[0025] Table 1. Results of compound fertilizer testing in each treatment group As shown in Table 1, the thiofosinate production process of the present invention effectively improves the compressive strength of the product and increases the yield by more than 10%.

[0026] Planting Trial The experimental crop was potato variety "Hezuo 88". The experiment consisted of four treatment groups: Example 1, Comparative Examples 1-2, and a control (using the same content of conventional compound fertilizer). Each plot had a planting area of ​​100m². 2 Repeat three times. The fertilizer application rate for each treatment group was 80 kg / hm² of P₂O₅. 2 Apply as a base fertilizer once, after the plants flower, at a rate of 80 kg / hm² of P₂O₅. 2 Each treatment fertilizer was applied again. The experiment was conducted in a randomized block design with a planting density of 3800 sq m. Other management practices were the same as routine field management.

[0027] Data measurement: When potatoes entered the budding stage, the height of 10 potato plants in each treatment group was measured (plant height: the distance from the base of the stem to the growing point). At the harvest time, all potatoes were harvested, and each plant was bagged separately. Twenty potato plants with similar results were selected, and the average weight of each potato plant was calculated. The above statistical data are shown in Table 2.

[0028] Table 2. Statistics of potato growth indicators in each treatment group As shown in Table 2, the fertilizer prepared by the production process of this invention effectively increases potato weight. Compared with Example 1, Comparative Example 1 shows a slight increase in plant height and a decrease in potato weight; Comparative Example 2 shows a significant decrease in plant height and a greater decrease in potato weight. This indicates that the fertilizer prepared by the thiophanate-methyl production process of this invention promotes high-quality and high-yield crop growth.

[0029] It should be noted that the above embodiments are merely some preferred embodiments of the present invention, and not all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

Claims

1. A method for preparing compound fertilizer by co-producing thiophosphorus urea, characterized in that, Includes the following steps: (1) First, phosphoric acid and urea with a molar ratio of 1:1 are stirred at a constant temperature between 70-90℃ for 1 hour; (2) The prepared urea phosphate slurry is transported to the buffer tank through a pipeline and then pumped to the tubular reactor. At the same time, urea phosphate and sulfuric acid are simultaneously introduced into the tubular reactor at a molar ratio of 1:

1. (3) The heat generated by the reaction of sulfuric acid and urea phosphate is used to further heat the mixed slurry to 90-110℃; (4) Spray the mixed slurry onto the material bed inside the granulator for granulation, and at the same time introduce ammonia gas into the material bed for neutralization reaction; (5) After going through drying, screening, cooling, coating and packaging processes, a qualified phosphorus thiourea compound fertilizer product is finally obtained. With the addition of external materials, any nitrogen, phosphorus and potassium ratio can be carried out. (6) The compressive strength of the thiophosphorus urea compound fertilizer produced can be significantly improved, and the compressive strength can reach 30N.

2. The method for preparing compound fertilizer by co-production of thiophosphorus urea process according to claim 1, characterized in that, In step (2), the sulfuric acid is 98% concentrated sulfuric acid.

3. The method for preparing compound fertilizer by co-production of thiophosphorus urea process according to claim 1, characterized in that, In step (1), the phosphoric acid concentration is 45%.

4. The method for preparing compound fertilizer by co-production of thiophosphorus urea process according to claim 1, characterized in that, In step (4), the amount of ammonia introduced is added according to a molar ratio of N:P of 1:

3.

5. The method for preparing compound fertilizer by co-production of thiophosphorus urea process according to claim 1, characterized in that, The nitrogen, phosphorus, and potassium content of the thiophosphorus-urea compound fertilizer product is 15-15-15 or 12-18-1.

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