Drum Granulator: Core of Particle Manufacturing
fertilizer granulator
Fundamental Principles of Granulation Technology
Granulators are essential equipment that transform powdered, lump, or molten raw materials into uniform particles. Their core working principle is based on three fundamental processes: “agglomeration, bonding, and forming.” Through external forces such as mechanical motion or fluid impact, raw material particles are brought closer together, and with the help of binding media, liquid bridges form on particle surfaces, ultimately resulting in stable granular products after drying and solidification.
The universal granulation process includes three basic steps: First, mixing and pretreatment, where powdered raw materials are uniformly mixed with binders; followed by the particle formation stage, where mechanical action causes the moistened raw materials to agglomerate into nuclei and gradually grow; finally, solidification and screening through drying and sieving to obtain qualified products.
Working Mechanism of Drum Granulators
In NPK compound fertilizer production, drum granulators have become the preferred equipment due to their outstanding performance, occupying over 60% of the market share. This equipment utilizes the rotational motion of an inclined drum to achieve continuous mixing, agglomeration, and granulation processes.
Material Feeding and Initial Mixing
Powdered raw materials such as urea powder, monoammonium phosphate powder, and potassium chloride powder are continuously fed into the drum inclined at 3-6 degrees after precise measurement. Simultaneously, 50%-70% concentration urea solution or other binders are evenly sprayed onto the material surface through atomizing nozzles, providing appropriate moisture to the powder.
Nuclei Formation and Particle Growth
Moistened powder begins to collide and adhere under the combined action of centrifugal force, gravity, and friction generated by drum rotation. Initially, microscopic nuclei approximately 0.5 mm in diameter form, which then continuously adsorb surrounding powder like rolling snowballs, gradually growing to the target particle size of 2-4 mm.
Particle Shaping and Strength Enhancement
During continuous rolling and collision within the drum, the internal structure of particles becomes more compact, and surfaces become smoother. Binders form solid bridges inside particles, significantly enhancing particle strength. Compound fertilizer particles typically need to achieve compressive strength of 15 Newtons per particle or more to ensure they don’t break during transportation.
Key Process Parameter Control
Successful granulation requires precise control of multiple key parameters. The drum inclination angle directly affects material movement speed – larger angles result in shorter residence times and smaller particles, while smaller angles allow longer granulation times and larger particle formation.
Drum rotation speed is another critical factor, typically maintained in the range of 15-30 rpm. Excessive speed causes materials to adhere to the drum wall due to centrifugal force, preventing effective rolling agglomeration; insufficient speed reduces particle collision frequency, affecting granulation efficiency.
Material moisture content must be strictly controlled between 8%-15%. Insufficient moisture results in inadequate viscosity, preventing stable particle formation; excessive moisture causes materials to form large lumps, affecting product quality and production continuity.
Technical Advantages and Application Prospects
The design of drum granulators perfectly aligns with the modern fertilizer industry’s requirements for large-scale, continuous production. Single production line capacity can reach 200,000-600,000 tons annually, with simple operation and maintenance, and excellent particle uniformity. Although there are certain requirements for raw material particle size (over 90% of powder must pass through an 80-mesh sieve), their outstanding comprehensive performance makes them the ideal choice for NPK compound fertilizer production.
With the growing global agricultural demand for efficient fertilizers, drum granulation technology will continue to play a central role in fertilizer production processes, providing reliable technical support for world food security.
Integrated Granulation Systems in Modern Fertilizer Manufacturing
The rotary drum granulator represents a cornerstone technology within the comprehensive npk manufacturing process, perfectly adapted for large-scale continuous production. This equipment’s efficiency is maximized when integrated with complementary machinery like the rotary screener, which ensures precise particle size classification and returns off-spec material for reprocessing. Together, they form a critical subsystem within the broader npk fertilizer production process.
While the drum granulator excels with specific raw materials, alternative technologies like the fertilizer compaction machine offer dry granulation solutions for different production needs. The ongoing advancement of npk fertilizer production technology continues to optimize these integrated systems, enhancing granulation efficiency, product quality, and overall sustainability in the global fertilizer industry to meet rising agricultural demands.