What does a Typical Pelletizing Process Look Like?

This article was authored by:

Jenny Seim
Technical Writer

Pelletization is an agglomeration process whereby material fines are “grown” through a tumbling motion in the presence of a liquid binder or water. While all agglomeration processes can be customized to suit the unique needs of the material being processed, in general, it follows these sequential steps:

1) Material fines can be pre-conditioned in a pin or paddle mixer. Not all pelletizing processes use a pre-conditioning step, but those that do see added benefits such as reduced binder use, increased production, and an improved end product.

2) After pre-conditioning, the material moves on to the disc pelletizer. For those that do not pre-condition, this is where the pelletization process begins. Here, material is continually fed to the disc pelletizer and wetted by a liquid binder spray.

The disc’s rotation causes the wetted fines to form small, seed-type particles (nucleation). The seed particles “snowball” by coalescence into larger particles until they reach their desired size and exit the pan. When a pre-conditioning step is used, seed pellets form in the mixer, and are enlarged and further rounded and refined on the disc pelletizer.

3) Finally, a belt conveyor transports the pellets to a rotary dryer if moisture removal is necessary. While reducing the moisture content, the dryer can also polish pellets into their final, hardened form.

Please see the flow diagram below for a visual representation of the pelletization process:

        1. Raw Feed
        2. Paddle/Pin Mixer
        3. Binder Feed
        4. Spray Rate
        5. Disc Pelletizer
        6. Feed Onto Pelletizer
        7. Binder Feed
        8. Liquid Spray System
        9. Transfer Conveyor
        10. Rotary Dryer
        11. Vibrating Screen
        12. Oversize Mill
        13. Recycle
        14. Surge Hopper

For more information on pelletization, download our Agglomeration Handbook, or contact us today!

About the Author . . .

Jenny Seim is a technical writer and service specialist.

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