In Australia, Wood Pellets are generally composed of sawdust, sawdust, mill waste, and even intact trees that are not suitable for wood. Some of the raw material may be sawdust, wood chips, lumber mill scrap, and even full trees unsuitable for lumber. The raw materials may be green, or freshly cut, may be partial dry or even kiln dried. By processing these raw material all in the same way, the end product has consistent moisture content, heat value, ash content, and burn characteristics. It is very important that all pellet manufacturers produce pellet to the same standard so that pellet appliances burn and heat consistently. Here are some of the processes:
Firstly, large pieces of wood will be processed by chipping machine to decompose these raw materials into smaller sizes, so as to be quickly consistent with drying and pressing particle mold.
If the granulator uses freshly cut raw materials, materials exposed to weather or high humidity, or mixed raw materials that may contain moisture, the sawdust must be dried to a consistent moisture level. Large dryer drums may use natural gas, propane, sawdust burners or other fuels to heat the drum to remove excess moisture.
After the drying process is completed, the dried sawdust enters the high-pressure mold. This process causes the sawdust to heat and release the natural lignin in the wood, and bond the sawdust together to form an identifiable shape of wood particles. The mill also determines the density, diameter, durability and length of the particles. All these characteristics are important for consistent particle equipment operation.
At the end of the process, the wood pellets remain at a high temperature from the drying and shaping stages, which will make them fragile and easy to break. In order to protect and strengthen the wood pellets, they will be sent to the cooling tower to reduce the temperature and harden the wood pellets. After cooling, they are usually stored in a large silo waiting for bagging or bulk distribution.
