The rotary drum granulator enables continuous granulation with daily outputs ranging from hundreds to over a thousand tons. The equipment consists of a massive rotating cylinder—typically over ten meters long and two to three meters in diameter. Powdered material enters at one end and, driven by the dual action of steam heating and the cylinder’s tumbling motion, gradually agglomerates while rolling; by the time it reaches the other end, it has transformed into uniform, spherical granules. Operating as a closed system, it is ideally suited for high-throughput, continuous industrial production. With a long-standing presence in the fertilizer industry, this granulator features mature technology and reliable performance, making it a proven, practical choice for fertilizer enterprises requiring stable, large-scale output.

Working Principle of Rotary Drum Granulator

Simply put, the granulation process works like making a “snowball” inside a large rotating cylinder. The cylinder rotates at a constant speed and a specific inclination angle. As powdered material continuously enters the feed end, it is carried upward by the inner cylinder wall before tumbling back down; this cycle creates a continuous curtain of material within the drum. Simultaneously, low-pressure steam is piped into the cylinder, heating the material to 50–70°C. Under this thermal influence, the various fertilizer components in the formulation undergo chemical reactions, generating a liquid phase. This liquid evenly coats the surface of the powder particles, acting as a natural binding agent. As the particles tumble and collide, they adhere to one another and gradually agglomerate; while growing by picking up new powder, they move toward the discharge end—driven by the cylinder’s tilt and rotation—and are finally discharged to complete the granulation process.

Common Issues for Rotary Drum Granulator

Granules fail to form or lack sufficient strength. This is usually caused by insufficient steam heat or a failure to raise the material temperature adequately, resulting in an insufficient liquid phase. If low steam pressure or poor condensate drainage prevents the internal temperature from meeting requirements, the powder particles lack the necessary binding force, resulting in loose, fragile granules.

Material sticking to the inner cylinder wall. Excessive steam or high initial moisture content in the feed material can cause a layer of wet material to paste onto the cylinder wall. This layer accumulates and thickens, eventually forming large clumps that break off and block the discharge outlet. Such buildup not only hampers production output but also risks damaging the cylinder’s lining plates when large clumps detach.

Excessive wear or abnormal noise during operation of the support rollers and thrust rollers. This is usually caused by inadequate lubrication or excessive axial movement (float) of the drum. The drum weighs tens of tons and relies entirely on sets of support rollers for load-bearing; if lubrication fails, the bearings will quickly burn out. If axial movement is not properly controlled, the thrust rollers are subjected to excessive force, exponentially accelerating wear.

Impact sounds or abnormal vibrations at the drive end of the large girth gear. This may be due to severe gear tooth wear or misalignment (lack of parallelism) between the axes of the pinion and the girth gear.