In the field of organic fertilizer granulation, a repeatedly validated rule holds true: the commercial value of a granule is largely determined the moment it leaves the granulator. However, the factors determining this value extend far beyond a single piece of equipment. The disc granulator handles the initial shaping—transforming powder into spheres—while the new “two-in-one” granulator employs an integrated approach to streamline the production chain; finally, the spheronizer bridges the gap between a granule that is merely “functional” and one that is “high-quality.” Each machine plays a distinct role, collectively forming a three-tiered progression in granule quality.
The core advantage of the disc granulator lies in its “visual operation.” As the tilted disc rotates, materials tumble and agglomerate along a parabolic trajectory, driven by the combined forces of gravity, centrifugal force, and friction. Operators can directly observe the granulation process inside the disc and make real-time adjustments to the tilt angle and water spray volume. The disc’s tilt angle is typically adjustable between 35° and 55°; a shallower angle results in a longer material residence time and larger granules. Rotation speed is inversely proportional to disc diameter; for a disc with a 2.2-meter diameter, the speed is generally maintained between 18 and 22 revolutions per minute. Disc granulation achieves a pelletization rate of 85% to 93%, producing granules with excellent sphericity and smooth surfaces. However, there is an unavoidable processing trade-off: granules produced via this wet granulation method have a moisture content of 8% to 12%. Consequently, they require downstream drying and cooling equipment to reduce moisture levels below 3% for safe storage, with coal costs alone amounting to 50–70 RMB per ton of finished product.
The breakthrough of the new “two-in-one” granulator lies in replacing a sequential process with an integrated one. Traditional processing methods require three separate machines—a mixer, a granulator, and a spheronizer—operating in sequence; transferring materials between these units is not only time-consuming but also leads to heat loss and granule breakage. The “two-in-one” model integrates these three stages into a single vessel: high-speed stirring pins at the front end shear and break up the material (rotating at 300–1,000 rpm); the middle section utilizes centrifugal force and mechanical extrusion to facilitate agglomeration; and a built-in polishing assembly at the rear performs real-time spheronization immediately after granule formation. For high-moisture, high-fiber materials like chicken manure and crop stalks, this integrated model achieves a stable pelletization rate exceeding 92% and accommodates a wider range of moisture content—handling fermented materials with 25% to 45% moisture directly, thereby eliminating the need for preliminary drying and fine pulverization.
The spheronizer addresses the limitations inherent in standard granulation equipment, which often focuses on initial formation while neglecting surface quality. Whether produced via disc granulation or extrusion, granules inevitably possess microscopic sharp edges or rough textures—disc-granulated pellets typically have a sphericity of only 0.6 to 0.7, while extruded pellets often exhibit a surface roughness (Ra) exceeding 6.3 micrometers. The spheronizer employs a high-speed rotating disc to generate centrifugal force, causing granules to tumble and rub against one another within the shaping chamber; this process gradually rounds off sharp edges and compacts or smooths out surface pits. The resulting granules achieve a sphericity of over 95% and exhibit enhanced density and compressive strength, making them more resistant to breakage and moisture absorption during storage.
The relationship between these three stages is not merely a linear sequence but a collaborative division of labor: the disc granulator focuses on “volume,” achieving the initial transformation from powder to pellet with a stable yield; the two-in-one granulator emphasizes “simplicity,” using an integrated design to shorten the process chain and reduce equipment investment; and the spheronizer focuses on “precision,” refining the surface and densifying the structure of the already-formed granules. For organic fertilizer products targeting the retail market, these three processing steps collectively determine the sphericity, strength, and marketability of the granules—qualities that are precisely the key to winning consumer favor for high-value categories such as horticultural fertilizers and fertilizers for household potted plants.