NPK compound fertilizer is a high-efficiency agricultural fertilizer integrating the three core nutrients—nitrogen, phosphorus, and potassium—designed to meet the growth requirements of various crops. Modern NPK production lines utilize an integrated, automated operational model, following a standardized workflow: pretreatment, proportioning and mixing, granulation, drying and cooling, screening and coating, and final packaging. This process ensures the precise transformation of raw materials into finished products, resulting in balanced nutrients, stable granules, and high utilization rates.

Raw material pretreatment serves as the foundation of production. Utilizing core raw materials such as urea, monoammonium phosphate (MAP), and potassium chloride, the line first employs crushers to pulverize lump materials into uniform powder, preventing clumping or impurities from affecting subsequent stages. Screening equipment then separates materials of uneven size; powders meeting specifications are stored in batching silos, while substandard materials are re-crushed. This ensures raw material purity and fineness at the source, laying the groundwork for precise proportioning.
Precise proportioning and mixing are critical for controlling nutrient content. An automatic batching system accurately weighs raw materials according to preset formulas, strictly controlling the N-P-K ratios to suit the specific fertilization needs of different crops and soil types. Once proportioned, the materials are fed into a double-shaft paddle mixer for thorough blending. Appropriate additives are introduced to adjust material viscosity and porosity, ensuring the uniform integration of nutrients and preventing nutrient imbalance in the final product.
Granulation is the key stage determining the fertilizer's appearance and performance. The uniformly mixed materials are fed into a rotary drum granulator. Here, the atomized granulation liquid is sprayed onto the material while the drum's rotation generates friction and compression, causing the powder to agglomerate into spherical granules. Strict control of moisture levels and rotation speed is essential during this stage to maximize the granulation rate, minimize powder waste, and optimize raw material utilization.
The drying, cooling, and screening stages are responsible for optimizing product quality. Formed granules are fed into a drum dryer, where excess internal moisture is removed at a constant temperature to prevent clumping caused by dampness. The hot, dried granules then pass through a cooler to lower their temperature and set their structure, thereby enhancing granule hardness and stability. Finally, multi-layer screening equipment is used to select qualified granules with uniform particle size; oversized and undersized granules are recycled for reprocessing to ensure consistent product specifications.
The final coating and packaging stages complete the production process. Qualified granules undergo an anti-caking coating machine treatment, which effectively extends the fertilizer's shelf life and enhances its slow-release performance. Following treatment, automated packaging equipment handles quantitative filling, sealing, and palletizing—a fully automated, efficient, and precise operation. The entire production line features seamless process integration and a high level of automation, combining efficiency with stability; it represents the mainstream process for large-scale compound fertilizer production.