The essence of organic fertilizer granulation lies in introducing energy into loose, powdered material to “lock” the particles together. However, the mechanisms used to achieve this “locking” vary significantly between different types of equipment: roller-press granulators utilize static pressure; New type organic fertilizer granulators employ impact and friction; and advanced “two-in-one” granulators rely on shear force. Because the form of energy input differs, the resulting granules—and the range of materials suitable for each process—also differ substantially.
Roller-press granulators operate based on static pressure. Dry powder is fed between two counter-rotating, high-strength rollers. Under the steady pressure exerted by a hydraulic system, the material is compacted into dense sheets, which are subsequently crushed and screened to produce granules. This method of energy application is gradual, uniform, and continuous. Since it generates no heat from impact, there is no need for drying or cooling systems, resulting in an overall energy consumption that is 30%–50% lower than that of wet-granulation processes. The trade-off is that this method is highly demanding regarding the state of the input material: the moisture content must be extremely low, and the particle size must remain consistent. Otherwise, the rollers may fail to “grip” the material effectively, leading to a sharp decline in the uniformity of granule strength. The roller shells are the most expensive wear parts in this process; those made of standard carbon steel typically require replacement every 3–6 months, while alloy steel shells can last for 1–2 years. This technology is well-suited for “dry and uniform” powders but is unsuitable for wet or soft materials.
New type organic fertilizer granulators, by contrast, utilize impact and friction. Through the combined action of high-speed mechanical agitation and aerodynamic forces, fine powders are continuously mixed, granulated, and rounded into spheres within the machine. Its primary strengths are high production capacity—reaching up to 20 tons per hour—and broad material adaptability; it can directly process fermented materials with a moisture content of 20%–40% without the need for pre-drying. The resulting granules are spherical, with a granulation rate exceeding 90%. However, the process does have requirements regarding particle fineness: the finer the input material, the better the sphericity and the higher the quality of the granules. The innovative two-in-one organic fertilizer granulator operates on the principle of shear friction. It integrates both mixing and granulation within a single chamber: high-speed stirring paddles at the inlet section shear and break down the material at speeds of 300–1,000 RPM; the middle section utilizes centrifugal force and mechanical compression to facilitate agglomeration; and the outlet section features an integrated polishing component that rounds the granules in real time. Characterized by a “shape-while-mixing” approach, the machine subjects the material to simultaneous fragmentation, agglomeration, and densification. It can process fermented materials with moisture content ranging from 25% to 45% directly, without the need for pre-drying. By consolidating processes that traditionally require multiple interconnected machines into a single primary unit, this system offers greater tolerance for fluctuations in raw material moisture. It is particularly well-suited for high-moisture, high-fiber materials, as well as for small-to-medium-scale production lines with limited space.
Three distinct forms of energy correspond to three different philosophies regarding material processing: static pressure relies on the belief that “firm compression ensures stability”; impact friction operates on the premise that “uniform rolling leads to successful granulation”; and shear friction is based on the concept that “simultaneous breakdown and agglomeration create a stable structure.” Before selecting a granulator, consider the nature of your material—its moisture level, particle size, and your required production capacity—as these factors will determine the optimal method for “locking” the material into its final granular form.