The roundness and uniformity of fertilizer granules directly impact the ease of application (spreading uniformity) and product competitiveness. Disc granulators, with their unique “rolling forming” principle, are key equipment for producing high-quality granules. The key lies in precisely controlling parameters to achieve the ideal shaping process within the disc.
Disc granulators do not rely on extrusion to form granules, but instead continuously roll the raw materials within a rotating disc. Initially small granules continuously absorb surrounding powder, gradually growing larger like a “snowball.” During this process, the granules rub against each other, naturally forming a rounded appearance. These granules are particularly suitable for products with high requirements for granule shape, such as organic fertilizers and biological fertilizers.
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Pellet quality is determined by several parameters. The first is the disc’s inclination angle. A small angle prolongs the material’s residence time within the disc, resulting in larger particles. A large angle causes the particles to overflow quickly, resulting in smaller particles. The second is the disc’s rotational speed. Low speeds are suitable for low-viscosity raw materials, preventing powder splashing; high speeds are suitable for sticky raw materials like organic fertilizer, enhancing the rolling adsorption effect. The third is the feed rate. Maintaining a uniform feed rate prevents excessive feed from causing particle accumulation and deformation, while insufficient feed leads to uneven particle size.
Furthermore, for fertilizers such as biofertilizers that require the preservation of bacterial inoculants, disc granulators eliminate the need for high-temperature extrusion. The forming process temperature is kept below 40°C, ensuring the survival of the inoculant. The resulting rounded particles are easy to package and transport, ensuring both functionality and commercial appeal.