Granulation is a key step in the post-processing of organic fertilizer production. It directly determines the appearance, strength, and storage and transportation performance of the finished fertilizer, and is also a core step in enhancing the market competitiveness of the product. After the organic raw materials have been decomposed, they need to be processed into granules by special equipment. Different production scales and raw material characteristics correspond to different granulation equipment. The following is a detailed explanation of the essential equipment and core functions of the granulation stage, based on industry practice, to help practitioners to scientifically select equipment and produce efficiently.
The core equipment in the granulation stage is the granulator, with auxiliary equipment working together to form a complete granulation process. Among them, the rotary drum granulator is the mainstream choice for large-scale production. It is suitable for organic raw materials with high viscosity and achieves granulation by physical rotation and chemical bonding. Its inclined cylinder rotates at low speed, causing the material to tumble under the action of centrifugal force and gravity. With the addition of binder by the spray system, uniform spherical granules are gradually formed. The size of the granules can be controlled by adjusting the rotation speed and tilt angle. It has a high degree of automation and is suitable for continuous large-scale production. It is widely used in the granulation processing of raw materials such as livestock and poultry manure and straw.
Flat die pellet machines are better suited for small to medium-sized production scenarios, especially family farms and small processing plants. This equipment uses compression molding technology, employing symmetrical double pressure rollers to extrude materials into dense granules with a granulation rate exceeding 98%. The granules are strong, not easily broken, and have low energy consumption. They are easy to operate, requiring no professional maintenance team, and are compatible with various well-rotted organic raw materials, perfectly solving the pain points of "low granulation rate and raw material waste" in small-scale production.
For high-moisture, high-fiber raw materials, a stirring tooth granulator is the preferred choice. It uses high-speed rotating stirring teeth to achieve forced mechanical agitation granulation, effectively breaking down fibers and mixed materials. It also has a self-cleaning function to prevent material from sticking to the walls, allowing for continuous and stable operation. The produced granules are uniform and smooth, suitable for granulating complex raw materials such as municipal sludge and sugar residue.
In addition to the core granulator, supporting equipment is indispensable. The raw material pretreatment stage requires a pulverizer to crush the matured raw materials to 80-100 mesh, ensuring granulation effect. A screening machine is used for grading and screening, returning substandard fine powder for re-granulation, improving the finished product qualification rate. Hot air drying equipment is used to reduce the moisture content of the granules, enhance their strength, and prevent clumping and mold growth during storage.
A proper combination of granulation equipment can improve production efficiency and ensure product quality. Large-scale manufacturers can choose a rotary drum granulator with a complete set of auxiliary equipment, while small-scale operators can prioritize flat die granulators. High-moisture raw materials are best suited for toothed granulators. Scientific selection and standardized operation are essential for efficient operation of the granulation process, promoting the upgrading of organic fertilizer products and contributing to the development of green agriculture.
