Granulation of fertilizer products offers one of the most feasible methods of producing granular multi-nutrient fertilizers, improving bulk storage, packaging quality and increasing ease of handling and application.
To achieve this, fertilizer producers rely on rotary drum granulators, which are known for their reliable operation and robust construction and are ideally suited to the broad and ever-changing needs of the fertilizer industry.
How rotary drum granulators Produce Quality Fertilizer Products
Particles relevant to this device are defined as solid spherical particles with a size range of approximately 1-6 mm. The physical properties and chemical composition of these particles may vary depending on the needs of the application.
Granulating rollers are often used to agglomerate inorganic fertilizers such as nitrogen, phosphorus and potassium (NPK); nitrogen (N), phosphate (P) and potassium (K) usually start as fine powders which can be granulated into what is called a composite The all-in-one fertilizer product can also be granulated separately and then mixed together to achieve the required nutritional formula. Without granulation, finely powdered materials can create dust that is difficult to handle; denser particles can settle to the bottom of bags or barrels, creating inconsistent mixing (separation) and creating significant application challenges.
Similarly, in the production of diammonium phosphate (DAP) or monoammonium phosphate (MAP), prilling drums are used for the continuous chemical reactions associated with the formation of solid particles. The reaction is traditionally initiated in a pre-neutralization tank, neutralizing the phosphoric acid slurry with ammonia while producing granules containing phosphate and nitrogen.
In addition to developing durable, consistent pellets, pelletizing drums can produce a more vibrant pellet product. Different liquid binders and coatings can be used to create granules with sustained-release properties, or multi-layered granules can be created by adding different minerals at different stages of the granulation process.
Rotary drum granulator design
The design of a rotary rotary drum granulator is relatively simple-raw material is fed into a large rotating drum, a liquid binder is added, and the material is tumbled to form solid spherical granules, in some cases utilizing chemical reactions as part of the process. However, extensive design and engineering is required to create high-quality equipment that can produce consistent products at high throughput.
Before beginning the design of a granulation drum, several issues must first be addressed, including:
Is the material organic or inorganic?
What are the nutritional contents?
Which adhesives are most effective at achieving the required release times while still preventing degradation during storage and shipping?
These and many other factors will affect the overall design of the pelleting drum.
After the material question has been answered, work moves to the dimensions of the drum, which will control the required output (usually measured in tons per hour {tph}).
Finally, rotation speed and drum slope need to be considered. In order to obtain consistent granules, the rotary drum granulator must run at a speed that allows the material to pour down the sides of the drum; too slow and the material will drag back and forth on the bottom of the drum; too fast and the material will stick to the drum wall due to centrifugal force. A perfect balance must be achieved.
Advances in Pelletizing Drum Design
Thanks to modern technology, almost all industries have experienced tremendous advancements. Some key advancements in granulation
drum design include:
Flexible and corrosion-resistant drum liners: Liners can be used to reduce or eliminate material buildup on drum walls and reduce the potential for damage from corrosive materials.
Tumbling Scrapers: Tumbling scrapers can be used to increase material agitation to perfect the cascading effect and produce the desired particle characteristics.
In conclusion
Pelletizing drums have long been the basis of modern fertilizer production. This versatile equipment helps bring numerous fertilizer products to the consumer market by creating durable granules that are easy to handle, package, transport and apply.
