What are the technological processes involved in a compound fertilizer production line?

Compound fertilizers, due to their balanced nutrients and long-lasting effects, are widely used in the cultivation of various crops. Their production line processes are rigorous and orderly, with each step closely linked, directly determining product quality and effectiveness. A complete compound fertilizer production line mainly includes five core stages: raw material processing, mixing and granulation, drying and cooling, grading and coating, and finished product packaging. Each process is interconnected, forming a standardized production system.

Raw material processing is the foundation of production and directly affects the accuracy of nutrient ratios in compound fertilizers. Workers will feed raw materials such as urea, ammonium phosphate, and potassium chloride into an automatic batching system according to market demand and soil testing results, mixing them in proportion while removing impurities and lumps to ensure the purity and fineness of the raw materials meet standards. Subsequently, the proportioned raw materials are fed into a mixer, where thorough stirring achieves uniform mixing, ensuring consistent fertilizer efficacy in subsequent granules and avoiding uneven nutrient distribution.

Mixing and granulation is the core process of the production line, consisting of two steps: mixing and granulation. The thoroughly mixed raw materials are fed into a granulator, which can be either a rotary drum granulator or an extrusion granulator, depending on the requirements. Through mechanical action, the raw material particles bind together to form uniformly sized spherical granules. Some production lines utilize advanced tubular reactor technology, allowing the raw materials to synthesize compound fertilizer during the reaction, further improving granule roundness and nutrient stability.

After granulation, the granules need to undergo drying and cooling to meet storage and transportation standards. The granules are first fed into a dryer, where high-temperature heat exchange removes internal moisture, increases granule strength, and prevents mold growth during storage. The dried granules are still at a high temperature and prone to clumping; therefore, they must be immediately sent to a cooler to lower the temperature to room temperature and further remove residual moisture, facilitating subsequent grading and packaging.

The grading and coating process optimizes product quality. After cooling, the granules pass through a grading sieve to screen out products with the correct particle size. Unqualified granules are crushed and returned to the granulator for secondary granulation, improving raw material utilization. Qualified granules are then coated with a special coating agent to increase granule brightness and roundness, while preventing moisture absorption and clumping, extending shelf life.

Finally, there's the finished product packaging stage. The coated granules are fed into a packaging machine, where they are automatically weighed, bagged, and sealed according to standard weight. They are then stored in a well-ventilated and dry warehouse for later use.

In summary, every step in the compound fertilizer production line is indispensable. From raw material selection to finished product delivery, meticulous control of every detail directly affects the quality and application effect of the fertilizer.