The NPK fertilizer production line is a coherent, automated production system that utilizes multiple devices to transform nitrogen, phosphorus, and potassium raw materials into standardized compound fertilizers. Strict process specifications must be adhered to throughout the entire process to ensure production efficiency and product quality. The core process is outlined below.

The raw material pretreatment section is the starting point of the production line. Nitrogen sources (urea, ammonium chloride), phosphorus sources (monoammonium phosphate, diammonium phosphate), and potassium sources (potassium chloride, potassium sulfate) are fed via conveyor belts to a pulverizer, where they are ground to a fineness of 80-100 mesh. The pulverized materials are then temporarily stored in a raw material silo. Simultaneously, samples are taken and sent to the laboratory for precise nutrient content measurement. Based on these test results, the central control system automatically calculates the mixing ratio and sets parameters for the subsequent mixing process, ensuring that the raw materials meet production standards.
The mixing and granulation section transforms the raw materials into granules. According to the ratio set by the central control system, the materials in the raw material silo are fed to the mixer via an automatic  batching system. They are then thoroughly mixed with the filler (talc) and binder (bentonite) for 10-15 minutes to form a uniform mixture. The mixture is fed into the granulation equipment via a screw conveyor. The production line typically uses a rotary drum granulator or an double roller press granulator. The rotary drum granulator uses a rotating drum to roll the material into balls, while the extrusion granulator uses a die to extrude and form granules with a diameter of 2-4mm, meeting the requirements of subsequent processing.
The drying and cooling stages ensure granule stability. After granulation, the wet granules enter a drum fertilizer dryer. Hot air at 120-150°C generated by a hot air furnace flows back through the granule layer, removing 30%-40% of the moisture and preventing granule clumping. After drying, the hot granules (80-100°C) immediately enter a cooler. A cooling system rapidly cools the granules to room temperature to prevent nutrient loss due to high temperatures. A dust removal device also removes fine dust and purifies the granules.
The screening and packaging stages complete the finished product production. After cooling, the granules are screened through a drum screener machine. Unqualified fines are returned to the granulation section for reuse, while larger granules are crushed and reused in a crusher. Qualified granules then enter a coating machine, where they are sprayed with a hydrophobic coating such as paraffin or resin to enhance anti-caking properties and sustained-release properties. Finally, the coated granules are weighed and bagged in a quantitative packaging machine. After sealing, they are conveyed to the finished product warehouse via a conveyor belt and shipped after passing inspection.