Granulation is a crucial step in the commercialization of organic fertilizer. High-quality granulation not only improves the fertilizer's storage and transportation performance but also enhances its competitiveness. Currently, the mainstream granulation methods include disc granulation, drum granulation, agitator granulation, and flat die granulation. The choice should be made by comprehensively considering the characteristics of the raw materials, production capacity, finished product requirements, and investment budget to avoid blindly selecting a method that leads to cost waste.
Disc granulation is suitable for medium-moisture raw materials with high viscosity, such as livestock and poultry manure and humic acid, and is the preferred choice for high-quality organic fertilizer. Its equipment structure is simple, investment costs are low, operation is convenient, and the produced granules are round and uniform with good marketability, achieving a granulation rate of over 90%. However, this method is a wet granulation process, resulting in a higher moisture content in the finished product, requiring supporting drying equipment. Furthermore, the single-machine capacity is limited, typically 1-5 tons per hour, making it unsuitable for large-scale continuous production.
Rotary drum granulation is primarily designed for large-scale production and is suitable for organic-inorganic compound fertilizers. Its production capacity is huge, with a single machine producing 5-50 tons per hour. It can operate continuously for 24 hours with stable performance and allows for flexible addition of fertilizer raw materials to reduce costs. However, the equipment is bulky, requires high investment, and necessitates large-scale drying and cooling equipment, resulting in high energy consumption. It is more suitable for large-scale agricultural input enterprises for mass production.
The stirring tooth granulator has wide adaptability, balancing efficiency and finished product quality, making it suitable for medium- to large-scale production. It has a fast granulation speed and low pulverization rate, capable of processing both high-moisture fermented materials and dry organic powders. Its closed-loop operation is more environmentally friendly. However, the equipment has a complex structure, higher purchase and maintenance costs, and requires strict control of raw material moisture content between 20% and 50%.
The flat die pellet machine prioritizes miniaturization and low cost, making it the preferred choice for startups and small-scale production. Its equipment is small in size, requires little floor space, has a low investment threshold, is simple to operate and maintain, and can process various organic raw materials without complex pretreatment. It is suitable for processing mixed raw materials such as straw powder and mushroom residue. However, this method has relatively low production capacity, with a single machine producing only 0.5-2 tons per hour. The granules are uneven in hardness and have a slightly higher pulverization rate, making it more suitable for small-batch, multi-batch production than large-scale mass production.
In summary, the core of selection is matching raw material suitability with production capacity: small-scale start-ups should choose flat die granulation; small to medium-sized producers of high-quality organic fertilizers should choose disc granulation; medium to large-scale producers seeking high efficiency and compatibility should choose stirring tooth granulation; and large-scale producers of compound fertilizers should choose rotary drum granulation. Reasonable selection can reduce costs and increase efficiency, making organic fertilizers more competitive in the market.
