NPK compound fertilizers, characterized by their balanced nutrient content and broad applicability, represent a mainstream fertilizer category in modern agriculture. Establishing a qualified NPK fertilizer production line requires a systematic approach—from initial planning and raw material processing to granulation and final packaging. Leveraging extensive experience in equipment integration, Huaqiang Heavy Industry has developed standardized construction and production workflows, ensuring the successful implementation of projects and consistent product quality.

The preliminary project phase serves as the foundation for the production line. This begins with determining production capacity and nutrient formulations based on market demand, followed by site surveys, process layout design, and the completion of necessary environmental and safety impact assessments. Equipment is selected according to the target capacity, encompassing batching systems, granulators, drying and cooling units, as well as screening and coating machinery. The layout of raw material storage, production workshops, and finished-product warehouses is carefully planned to optimize material flow and minimize handling losses.
Raw material pre-treatment and automated batching constitute the first stage of production. Common raw materials—such as urea, monoammonium phosphate (MAP), potassium chloride, and various fillers—are processed; large particles are first crushed to ensure uniform fineness. A automatic batching system precisely measures each ingredient according to the specified formula, automatically handling the batching process. The materials are then conveyed to a mixer, where they are thoroughly blended to ensure a homogeneous distribution of nitrogen, phosphorus, and potassium, preventing localized nutrient imbalances and preparing the mixture for granulation.
The blended material then enters the granulation stage, which is the core of the entire production line. The most common method is rotary drum granulation, where powdered material—aided by the addition of steam or a binder—rolls and agglomerates within a rotating drum to form fertilizer granules. During this process, parameters such as moisture content, drum rotation speed, and material feed rate must be strictly controlled to maximize the granulation yield and minimize the amount of fine-powder "rework" (material that fails to form proper granules).
Freshly formed granules typically have high moisture content and a loose structure, necessitating subsequent drying and cooling. In the drying stage, a drum dryer is used to regulate temperature and remove excess moisture. The granules then pass through a cooler to lower their temperature, which helps prevent caking during storage or subsequent handling. After cooling, the product is sent to a vibrating screen for classification. Granules that meet specifications proceed to the next stage, while oversized clumps and fine dust are returned to the batching section for re-granulation, thereby maximizing raw material utilization.
The screened, qualified granules can undergo a coating process, where an anti-caking agent is applied to their surface to improve flowability and extend shelf life. Finally, an automated packaging machine handles quantitative bagging, sealing, and coding, after which the product is moved to storage.
Throughout the operation of the production line, an integrated dust collection system captures airborne particles, ensuring clean production. Routine equipment inspections and formula verification are essential to maintain a consistent output of NPK compound fertilizer—characterized by well-rounded granules, precise nutrient content, and high resistance to caking. This well-designed process not only reduces energy consumption but also simplifies long-term operation and maintenance, helping fertilizer manufacturers achieve stable, reliable production.