NPK compound fertilizer is a high-efficiency agricultural fertilizer rich in the three major nutrients—nitrogen, phosphorus, and potassium—making it suitable for the growth needs of most crops. Modern NPK compound fertilizer production lines feature mature technology and a high degree of automation; the entire process is tightly integrated and strictly controlled, forming a standardized closed-loop system from raw material processing to finished product dispatch. This effectively ensures nutrient uniformity, granule stability, and consistent quality. The core process consists of six main stages: raw material pretreatment, batching and mixing, granulation, drying and cooling, screening and coating, and final packaging.

Raw material pretreatment is the foundational stage of production. The line begins by screening and crushing basic raw materials—such as urea, monoammonium phosphate (MAP), and potassium chloride—to remove impurities and lumps, grinding all materials to a uniform fineness of less than 1.5 mm. Fine powder processing improves the uniformity of the subsequent mixture, prevents nutrient segregation, and lays a solid foundation for stable granulation and balanced fertilizer efficacy; it also reduces equipment wear and ensures smooth production operations.
Batching and mixing is the critical process for controlling nutrient ratios. Utilizing an automated batching system, raw materials are precisely measured according to preset formulas to meet the specific fertilization requirements of different crops and soil types. The measured materials are fed into a horizontal ribbon mixer, where thorough agitation ensures the uniform blending of nitrogen, phosphorus, and potassium sources, as well as secondary nutrients and trace elements. This guarantees precise and consistent nutrient ratios in every batch, ensuring stable product quality from the very start.
Granulation is the key step in shaping the product. The uniformly mixed powder is fed into a rotary drum granulator. The equipment rotates at a constant speed to tumble the material, while the addition of steam or water acts as a binder, causing the powder to gradually agglomerate and roll into spherical granules. This process yields a high formation rate and produces round, uniform granules suitable for large-scale industrial production; compared to extrusion granulation, the finished product offers better solubility and a more stable release of nutrients.
Drying and cooling directly determine the storage stability of the finished product. Freshly formed wet granules have high moisture content and are prone to clumping or degradation; they must be fed into a rotary dryer where a stream of hot air at 300–400°C reduces their moisture content to below 2%. The hot, dried granules then enter a cooler, where cold air brings them down to ambient temperature; this process further solidifies the granule structure and increases hardness, effectively preventing clumping or breakage during subsequent storage and transport.
Screening, coating, and packaging constitute the final stages of the process. Cooled granules pass through a vibrating screen to separate those meeting size specifications, while broken granules and fines are recycled for re-granulation. Qualified granules undergo a coating process that effectively protects against moisture, clumping, and nutrient loss, thereby extending the fertilizer's shelf life. Finally, automated packaging equipment handles precise weighing, bag sealing, and palletizing, preparing the finished product for warehousing and sale.
The entire NPK compound fertilizer production process is scientifically rigorous, with precisely coordinated stages that ensure efficient, stable production and yield high-quality products with balanced nutrients; it represents a core process system for modern, large-scale fertilizer manufacturing.