The fertilizer coating process relies on the coordinated operation of "material conveying, coating material atomization, and uniform coating". The key steps are as follows:

• Granule Feeding: Granular fertilizers (with a particle size of 2-5 mm and a moisture content of ≤15% to prevent caking) are evenly fed into the rotating coating drum via a conveyor.
• Coating Material Preparation: Coating materials (such as polymer resins, sulfur, humic acid, or microbial agents) are mixed with solvents (water or organic solvents) to form a uniform coating slurry or emulsion.
• Atomization and Spraying: The coating material is atomized into fine droplets through a high-pressure spray gun installed inside the drum, and evenly sprayed onto the surface of the rolling fertilizer granules.
• Uniform Coating: As the drum rotates continuously (at a speed of 10-20 revolutions per minute, adjustable according to the particle size), the fertilizer granules keep tumbling inside the drum, ensuring that the atomized coating material adheres uniformly to the surface of each granule.