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Table of Contents
What is sawdust, and what potential does it have globally?
Sawdust or wood dust is a result of using a saw or other tool to cut, grind, drill, sand, or otherwise pulverizing wood. One of the greatest starting materials for making fuel pellets is sawdust, which is abundantly available.
According to Dr. M. Junginger’s picture from Global Sawdust Potentials and Pellet Supply Chains, there is a potential for sawdust of around 75Mm3, of which 2/3 may be found in Brazil, Russia, Canada, and China. The large-scale manufacture of wood pellet mill is made possible by the availability of a lot of sawdust from sawmills and planing mills at a reasonable price.
Which type of sawdust, softwood or hardwood, is the best raw material for producing pellets?
The density, lignin, and extractive content of the wood species used to make the sawdust all affect its heat value. The calorific values of softwood sawdust are greater than those of hardwood because softwoods contain more lignin than hardwoods do. Additionally, lignin acts as a natural binder for the creation of sawdust pellets, making softwood sawdust preferable to hardwood in this regard. For the manufacturing of pellets, hardwood and softwood sawdust are often combined.
How to use a sawdust pellet mill to produce high-quality pellets?
preparing sawdust
The moisture level of the sawdust should be checked when it enters the facility that makes sawdust pellets. The amount of water that may evaporate is indicated by the material’s moisture content. Sawdust with a high moisture level has to be kept apart from sawdust with low moisture content.
For the manufacturing of 1 tonne of pellets, 7 bulk m3 of sawdust with a moisture level of 50 to 55 percent is required. Sawdust should have a moisture level of 10-15% at the most. Before entering the sawdust pelletizer, sawdust with a higher moisture level has to be dried; sawdust with a lower moisture content can omit the step.
Drying
Because wet sawdust requires more energy to hammer than dry sawdust does, it should be dried before size reduction. Additionally, the screening may be jeopardized by the wet sawdust clogging or smearing the screen. The dryers are capable of drying.
Screening
The screening of the sawdust is done to get rid of any rocks, plastic, metal, or other hard objects that might harm the machinery. While the metals are captured by a magnet when the sawdust travels over the screen, the stones and other hard objects that resemble stones are removed by a stone trap.
Hammering
The purpose of the hammering is to uniformize the size of the sawdust. There may be wood lumps, dead knots, etc. in the mountains of sawdust that need to be pounded to fit through the die holes of the machines that turn the sawdust into pellets.
Pelletizing
When sawdust enters the pelletizing chamber of the sawdust pellet machine, the heat created by the machine’s operation heats the sawdust’s lignin to 120–130 °C, where it is plasticized and bonds the particles together to aid in the molding of the pellets.
The pellets are formed by pressing them through the sawdust pellet machines’ pellet dies, and then the cutter trims them off to the proper length. The binder may be required during the pelletizing process to increase the strength and longevity of the pellets.
Cooling
Cooling When the sawdust pellet machines produce them, the pellets are hot and plastic. The ultimate moisture content after the cooler can be as low as 6%, which may be raised to 8 to 10% by collecting moisture from the surrounding air. Then they need to be cooled down to become hard and stiff and dry up.
Packaging
The pellets will undergo a second screening to recycle the particles before packing. The pellets will subsequently be packed. The pellets are usually packaged into bags that weigh 12, 15, or 20 kilograms for home use.
When being exported, the pellets are often delivered in bulk or one-tone bags that are covered in plastic to keep moisture out. Small bags are preferable for pellets compared to big bulks or bags since they experience less abrasion during distribution.
