The Pelletizing Process of Fertilizer Roller Press Granulators

Extrusion granulation is a non-drying, room-temperature forming process that uses mechanical pressure to directly compress dry powder materials into granules. The entire pelletizing process of fertilizer roller press granulators is stable and efficient, suitable for the production of various fertilizers such as compound fertilizers, organic fertilizers, and blended fertilizers. First, there is the raw material pretreatment stage. Urea, ammonium phosphate, potash fertilizer, and other raw materials are mixed and pulverized according to the formula, with the moisture content controlled at 2%–5%. Good flowability and no clumping of the dry powder are essential to ensure uniform extrusion and prevent loose or cracked granules. Next, the forced feeding stage begins. The material is evenly fed into the roller extrusion zone by a screw feeder. The screw propels the material, generating pre-pressure to prevent material from being lifted out of the container or to ensure stable feeding, thus ensuring consistent material density between the two rollers and laying the foundation for forming. The core process is high-pressure extrusion molding. The material enters between a pair of relatively rotating pressure rollers. Under high pressure, the voids between the particles are compacted, the intermolecular bonding force is strengthened, and the material is extruded into a continuous sheet-like cake. The pressure rollers are engraved with regularly spaced hemispherical or waist-shaped die holes. The pressure directly determines the density and strength of the granules. Then comes crushing and grading. The dense granules are crushed into smaller pieces by a crusher, and then polished and shaped by a pelletizer to remove sharp edges and make the shape closer to round granules. Unqualified fine powder and large particles are separated by sieving and returned to the extrusion process, achieving a closed-loop cycle. Finally, there is polishing and finished product. Qualified granules enter a polishing machine for further rounding and polishing, improving the roundness and smoothness of the appearance. After cooling, they become finished granules. The entire process requires no water addition or drying, has low energy consumption, produces high-hardness granules, and prevents moisture absorption, making it suitable for large-scale fertilizer roller press granaultor produciton lines.

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