Answer: An NPK compound fertilizer production line consists of a series of interconnected key pieces of equipment, each with a specific role, working in sequence to achieve standardized production. The automatic batching system is the first critical unit; it precisely measures nitrogen, phosphorus, potassium, and auxiliary ingredients, strictly controlling the formula ratios to ensure the final product meets nutrient standards. The crusher breaks down lumps and large raw material chunks, reducing particle size and preventing agglomeration, thereby laying a solid foundation for the subsequent mixing and granulation stages.

The mixer ensures thorough blending, fully combining the proportioned raw materials to guarantee uniform nutrient distribution and prevent localized nutrient imbalances in the fertilizer. The granulator is the core piece of equipment in the line; it processes the mixed powder into uniform, dense granules via roller pressing or extrusion, determining the final shape and quality of the fertilizer. The dryer removes excess internal moisture, increasing granule hardness and preventing the finished product from becoming damp or moldy.
The cooler rapidly lowers the temperature of the hot, dried granules, stabilizing their properties for easier storage and further processing. The screening machine precisely sorts the granules, separating fines, powder, and substandard particles to ensure product uniformity. Finally, the coating machine applies an anti-caking treatment to extend the fertilizer's shelf life, while the packaging machine performs automatic, quantitative bagging, completing the fully automated, closed-loop production process.