2026/07/10
Raw material factors: Moisture content is the most critical variable. Wet granulation processes (using rotary drum or disc granulators) require the input moisture to remain stable between 28% and 35%; fluctuations exceeding ±3% lead to a significant drop in the granulation rate. Particle fineness is equally important; input powder should be ≥60 mesh (achieved using cage crushers or semi-wet material crushers). Fine powders offer a large specific surface area and strong adhesion, facilitating rapid pellet formation. Conversely, excessive fiber content (>15%) hinders the rolling and densification of granules, resulting in low granulation rates and fragile pellets.
Equipment parameter factors: For disc granulators, the tilt angle (40°–55°) and rotational speed (10–18 rpm) are critical parameters. An angle that is too shallow results in prolonged material retention and oversized granules, while an angle that is too steep causes material to slide off prematurely, leading to incomplete granulation. For rotary drum granulators, the rotational speed (10–15 rpm) and inclination (2°–4°) must also be precisely matched to the material's characteristics. Improper scraper positioning can cause material buildup on the disc bottom or drum wall, disrupting the material's movement trajectory and resulting in uneven granulation.
Operational factors: The atomization performance of the liquid spraying system directly impacts the granulation rate. Droplets that are too coarse (>300 μm) cause localized over-wetting and the formation of large clumps, while droplets that are too fine (<50 μm) lack sufficient adhesive force. The use of dual-fluid nozzles is recommended to maintain droplet sizes between 100 and 200 μm. Feed rate must match the granulator's capacity; an excessive rate leaves insufficient time for material to form pellets, while a rate that is too slow causes excessive rolling of granules inside the machine, generating large amounts of fine powder. Rapid optimization method: When the pelletization rate falls below 70%, first check the raw material moisture content, then inspect equipment parameters, and finally observe the uniformity of the liquid spray. It is recommended to create a "pelletization rate vs. parameters" reference table to record optimal parameter combinations for various material conditions and establish standardized operating guidelines. In practice, adjusting the recycle ratio (30%–50%) can rapidly improve pelletization conditions, increase the number of "nuclei," and promote the adhesion and growth of fine powder.