NPK fertilizer granules are a type of compound fertilizer that combines the three core nutrients: nitrogen, phosphorus, and potassium.  Their granular form offers advantages such as ease of storage and transportation, uniform application, and long-lasting fertilizer effect, making them widely used in various crop cultivation. Their production requires precise proportioning and scientific granulation, with the core process encompassing five main stages: raw material pretreatment, proportioning and mixing, granulation and shaping, drying and cooling, and finished product screening.

Raw material pretreatment is fundamental, requiring the selection of high-purity nitrogen, phosphorus, and potassium raw materials and auxiliary materials. Nitrogen sources commonly include urea and ammonium sulfate; phosphorus sources can be diammonium phosphate and superphosphate; and potassium sources often use potassium chloride or potassium sulfate.  Auxiliary materials include binders to improve moldability and anti-caking agents to ensure storage stability. The raw materials must be crushed and sieved to remove impurities and refine particle size, preventing any impact on subsequent mixing uniformity and granulation effect. An automatic batching system is used for quantitative feeding, following the "less first, then more" principle, adding trace elements and auxiliary materials first, then mixing in the main raw materials. Thorough mixing with a double-screw mixer ensures uniform nutrient distribution and prevents nutrient imbalance in the granules.
Granulation and shaping is the core process, commonly using drum granulation, extrusion granulation, or high-tower granulation processes. NPK fertilizer granulators are the core equipment in this stage, adaptable to different scales of NPK fertilizer production lines. Small and medium-sized production lines often use drum granulation, where the mixed material is fed into a rotating drum, and steam or water is sprayed as a binder to form rounded granules through agglomeration; extrusion granulation is suitable for heat-sensitive raw materials, forming high-strength granules through high-pressure extrusion; high-tower granulation is suitable for high-concentration products, where the raw materials are melted and then sprayed for cooling and solidification, resulting in smooth and easily soluble granules.
After shaping, drying, cooling, and screening are required. The drying stage controls the temperature to remove excess moisture, preventing granule caking and mildew; after cooling, the granules are screened and graded. Unqualified large granules are crushed and recycled, and fine powders are re-granulated to improve raw material utilization. Finally, a coating treatment can be applied to further enhance anti-caking properties. After quality inspection, the finished product is packaged and stored.
The production of NPK fertilizers requires strict control of parameters such as temperature and moisture to prevent nutrient loss and ensure particle strength and uniform particle size. A scientifically standardized production process allows NPK fertilizer granules to fully utilize their synergistic nutrient effects, contributing to improved quality and efficiency in agriculture.