Drum granulator is a granulation equipment widely used in the fertilizer, chemical, food and other industries. Its working principle is based on the combination of physical and chemical processes, mainly completed through the following steps:
Raw material mixing and pretreatment:
Firstly, various raw materials (such as nitrogen, phosphorus, and potassium compounds in NPK fertilizers) are mixed in a certain proportion. The raw materials may need to be crushed, sieved, or pre dried to ensure their uniform dispersion during the granulation process.
Granulation process:
The raw materials enter the cylindrical granulation chamber of the rotary drum granulator, which is composed of a tilted and slowly rotating cylinder. The raw material forms a spiral motion under the action of the rotational force and centrifugal force of the cylinder.
In the granulation room, the raw materials are evenly sprayed with appropriate amount of water or binder through the spray system. The function of water or binder is to enhance the cohesion between particles and promote the aggregation of small particles into larger ones. This process is called “drum granulation” or “rotary granulation”.
Particle growth and solidification:
As the cylinder rotates, small particles gradually grow through rolling and collision. Moisture or binders allow the components in the raw materials to adhere at the contact points, forming a more stable structure.
During the granulation process, the size and shape of the particles can be controlled by adjusting the rotation speed of the cylinder, the water spray system, and the feeding rate of the raw materials. The longer the particles roll inside the cylinder, the larger the particle size will generally be.
Particle screening and post-processing:
After granulation is completed, the particles are passed through a sieve or screening device at the end of the cylinder to remove oversized or undersized particles, ensuring uniform particle size in the final product.
The particles may also need to be dried to remove excess moisture and prevent clumping during storage and transportation. In some cases, cooling, polishing, or coating treatment may also be necessary to improve the hardness and stability of the particles.
The working principle of a rotary drum granulator is to use the combination of physical motion (such as rotation and rolling) and chemical action (such as the addition of moisture or binders) to form uniform and stable particles of raw materials. This process can not only improve the efficiency of raw material utilization, but also customize the size, shape, and hardness of particles according to specific needs to meet the needs of different industries and applications.