The production process of compound fertilizers generally includes the following steps:

Raw Material Proportioning:
Based on market demands and the results of soil tests in various regions, raw materials such as urea, ammonium nitrate, ammonium chloride, ammonium sulfate, monoammonium phosphate, diammonium phosphate, triple superphosphate, single superphosphate, potassium chloride, and potassium sulfate are selected and proportioned in a certain ratio. This step requires precise measurement and a scientific formula to ensure that the nutrient content of the compound fertilizer meets the standards.
Raw Material Mixing: The proportioned raw materials are mixed to make various raw materials fully and evenly blended, thereby improving the overall uniform nutrient content of the fertilizer granules. The mixing process can be carried out using horizontal mixers or pan mixers and other equipment.
Lump Crushing (Some Processes Have This Step):

The large lumps of raw materials that may occur after mixing and stirring are crushed for subsequent granulation processing. Commonly used crushing equipment includes chain crushers. After crushing, the particle size of the raw materials is more uniform, which is beneficial to improving the quality and efficiency of granulation.
Material Granulation:

The evenly mixed and crushed materials are sent to the granulator for granulation through a belt conveyor. Commonly used granulators include rotary drum granulators, extrusion granulators, and disc granulators. During the granulation process, the materials form granules under certain conditions. The specific granulation method and equipment selection will depend on the production process and product requirements.
Primary Screening:

The semi-finished granules after granulation are initially screened to remove unqualified granules. The unqualified granules are returned to the mixing and stirring stage for reprocessing, while the qualified granules proceed to the next step. Generally, a drum sieve is used for screening, and the aperture of the sieve mesh is selected according to the product requirements.
Granule Drying:

The qualified granules after the primary screening are sent to the dryer to remove the moisture contained in the granules, increase the strength of the granules, and facilitate storage. During the drying process, the temperature and time need to be well controlled to ensure the quality of the granules. Commonly used dryers include rotary drum dryers, and the water content of the dried granules is generally required to be within a certain range, such as about 1.5%.
Granule Cooling:

The temperature of the dried fertilizer granules is too high, and they are prone to caking, so they need to be cooled. The cooled granules are convenient for bagging, storage, and transportation. The cooling process can be carried out using a cooler to reduce the temperature of the granules to an appropriate range, such as less than 40°C.
Granule Secondary Classification:

The cooled granules are further classified and screened to remove unqualified granules. The unqualified granules are crushed and then re-granulated, while the qualified products proceed to the next step. This step can use a secondary drum sieve and other equipment to ensure that the particle size of the product meets the requirements.
Finished Product Coating:

The qualified products are coated to increase the brightness and roundness of the granules, making their appearance more attractive. At the same time, it can also improve the anti-caking performance and storage stability of the product. The coating process is generally carried out using a coating machine, and the selection and amount of coating agent need to be adjusted according to the product requirements.
Finished Product Packaging:

The coated finished granules are sent to the silo for temporary storage through a belt conveyor, and then connected to an electronic quantitative packaging scale, a sewing machine and other equipment for automatic quantitative packaging and sealing. The packaged finished products are placed in a ventilated place for storage.

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