Tag: fertilizer granulator

When adding functional ingredients such as slow-release agents, biological agents, and trace elements to BB fertilizer, the BB fertilizer blender requires special adjustments to prevent the additive effects from being lost or unevenly distributed during the blending process.
Biological agents (such as Bacillus subtilis) are sensitive to high temperatures and easily inactivated. Therefore, two key controls must be implemented during blending: first, the blending temperature. By installing a cooling jacket on the BB fertilizer blender barrel, the chamber temperature can be kept below 35°C to prevent frictional heating from the blades, which could reduce the activity of the agent. Second, the mixing order: pre-mix the agent with 10 times the amount of carrier (such as humus powder) to form a “mother powder.” This should then be added after the blender has been running for 5 minutes. This minimizes direct friction between the agent and other ingredients and ensures a viable bacterial count retention rate exceeding 90%.

If adding a slow-release agent, to avoid damaging the coating during mixing, use a “low-shear” impeller (with blunted blade edges), reduce the speed to 15-18 rpm, and control the mixing time to ≤8 minutes. This prevents the slow-release agent particles from excessively colliding and causing the coating to crack, thereby losing its slow-release effect.
For trace elements, they should first be crushed to a size of 100 mesh or larger, pre-diluted with five times the amount of powdered fertilizer (such as monoammonium phosphate powder), and then added to the BB fertilizer blender using a “multi-point feeding” method to ensure even distribution of the trace elements and avoid localized high concentrations that could cause fertilizer damage to the crop.

The granulation performance of a ring die granulator isn’t solely determined by the equipment itself. Linkage optimization with the front-end crushing, mixing, and conditioning processes can significantly improve production efficiency and pellet quality.
During the crushing process, the raw material particle size must be matched to the ring die aperture. For an 8mm ring die aperture, the raw material particle size should be controlled below 2mm, with a particle size deviation of no more than 0.5mm, to prevent large particles from clogging the die aperture. A grading screen can be installed at the pulverizer outlet, with the screen aperture set to 1/4 the ring die aperture, to ensure uniform particle size and reduce the frequency of granulator downtime for cleaning. If the raw material contains a high amount of coarse fiber (such as straw powder), the pulverizer should use a hammer-type mechanism to enhance crushing efficiency.

The mixing process must ensure uniformity among the raw materials, binders, and nutrients. Uneven mixing can result in insufficient nutrients or insufficient strength in some pellets. A typical requirement for uniformity is a coefficient of variation of ≤7%. This can be achieved by adjusting the mixer speed (30-40 rpm) and mixing time (5-8 minutes). Sampling points should be set up at the fertilizer mixer outlet for hourly testing.
During the conditioning process, the steam supply should be adjusted according to the production speed of the ring die granulator. For example, if the pelletizer processes 5 tons of raw materials per hour, the steam supply should be maintained at a stable 0.3-0.4 tons/hour, monitored in real time by a flow meter. If the pelletizer speed is increased to 6 tons/hour, the steam supply should be increased to 0.45-0.5 tons/hour to prevent the raw materials from being too dry or too wet.
By coordinating the speed and flow of the front-end and pelletizer, production efficiency can be increased by 10%-15%, reducing downtime caused by process disconnects.

Fertilizer pellets are prone to clumping during storage and transportation. Through scientific design, coating machines address this issue at its root, focusing on the following key aspects.
First, uniform film coating and protection. The coating machine uses vibrating feeders, combined with guide plates, to evenly distribute pellets. Even pellets of varying sizes are diverted by the guide plates, ensuring that every pellet contacts the film. The symmetrical film guide mechanism wraps the pellets from all sides, creating a complete seal that blocks moisture from reaching the pellets and prevents moisture absorption and clumping. Furthermore, the film tension is precisely controlled, with an error within ±2N. This prevents over-tightening of the pellets, keeping them loose and facilitating even spreading during subsequent fertilization.

Second, precise temperature control is crucial. During the heat-sealing stage, the coating machine uses an intelligent thermostat to maintain a stable temperature of 100-150°C and monitors temperature fluctuations in real time, with fluctuations within ±5°C. This ensures that the film adheres tightly to the pellets, forming a strong protective layer. It also prevents high temperatures from damaging anti-caking components in the fertilizer (such as the coating agents in some slow-release fertilizers), preserving the pellets’ inherent anti-caking properties. The hot air circulation design also ensures a uniform temperature throughout the packaging, preventing uneven shrinkage of the film and damaging the protective layer. Even the slightest movement of the pellets within the package prevents the film from rupturing.