What Material Particle Size Does The Pellet Mill Require?

Before you can use you wood or other biomass material in the pellet mill you must first reduce it to a suitable particle size. As a general rule you want to reduce the particles to a smaller diameter than the holes in the die. Generally this means milling through a screen with 4 or 5mm holes. The type of size reduction equipment you should use depends on your raw material. Most materials before they are used in the pellet mill are passed through a hammer mill with a suitable screen size. However the hammer mill cannot used to be process all materials from the start. Only materials with a diameter of around an inch should be used in the hammer mill. Therefore this includes wood chip and chopped straw/grasses. Therefore if you have logs you need to go through several size reduction steps, firstly you will chip the logs. You can then process the chips through the hammer mill. With logs the moisture content is more than often still too high and will require drying before it can be used in the pellet mill. If dealing with straws and grasses these can be loaded directly into the hammer mill if properly metered in. The hammer mill does not like inconsistent loading, therefore in this respect it is very similar to the pellet mill. To deal with straws and grasses in volume it is normally better to process through a bale chopper/shredder which then feeds the hammer mill. Also as an important note you cannot put high moisture content materials through the hammer mill without a risk of blocking the screen. The best particle size does depend on the raw material, but it is worth experimenting with. Research has show that a smaller particle size can produce a higher quality pellet in the pellet mill. However research has also show material which is milled to fine (a dust) has issues with traction between the roller and die. Therefore particle size can also effect the quality of the pellets and the productivity of the pellet mill. Therefore its best to have a variety of screens for the hammer mill to test which is best.

 The Wood Pellet Mill Production Guide © PelHeat Ltd - What Material Particle Size Does The Pellet Mill Require?