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Biomass Pellet

Wood and Biomass

Biofuel pellets or Refuse Derived Fuel (RDF-5) made from biomass waste is becoming common as one of the renewable energy sources.
IDAH provides core pieces of equipment and solutions in resource recovery and production of biofuel pellets production.
Raw material for biomass pellet:
Agricultural waste: crop stalk and straw material, rice husk, cotton stalk, coffee husk, alfalfa straw, coconut shell, palm shell, sugarcane bagasse, etc.
Forestry residue: sawmill residue, branches, bark, leaves, etc.
Solid waste: junk paper, waste plastic, cardboard, etc.
A high-quality biomass pellet would result in a higher calorific value with lower moisture and ash contents.

Biomass pellet mill

Receiving Raw Material

The raw material comes in different shape. A sorting machine will be needed to separate inorganic material.

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The magnet is needed to separate magnetic metals, which can interfere with the grinding process.

Pre-grinding (crushing)

The pre-grinding is needed to lower the material size.


The material usually comes in high humidity, a drying process is needed to lower the moisture content

Airflow selection

This is the final classification to remove impurities.


This step is the last grinding process before material enters pelleting system.


Pelleting starts with pre-conditioning, adding steam to further hydrate, and cook the material before entering the pelleting chamber to be formed into pellets.


Cooling utilizes ambient air to cool down the hot pellet from the pellet mill.
Thorough cooling is needed to prevent condensation inside the packaging.


Packing gives protection to the pellets and also give easiness to handle and transport to customer's hand

Biomass sorting facility

Pelleting process description for biomass pellet

Sorting system Incoming material will undergo physical separation (by airflow, gravity, and magnetic force) to separate organic material from inorganic impurities.
Raw material intake system Consisting of tip hopper, mechanical conveyors, and elevators into storage bins. For wood pellet, the material can be sawdust, straw meal, and other biomass sources.
Grinding system A size reduction process for raw materials that contain large particulates. The ground material is conveyed to storage bins. (Location for this grinding system can be designed to suit the process flow that follows).
Mixing system Other sources like liquid and oil are now added and mixed with raw material in batches. After mixing the material is ready for pelleting.
Pelleting with Pre-conditioning The mixer feeds down through a feed hopper into the feed screws which meter the ingredients into the conditioner. Due to its nature, biomass material will have low flowability. A force feeder is needed to feed the material to the pelleting chamber. IDAH's pellet mill produces pellets at high capacity, low energy consumption, and high pellets quality. With a special die and rolls design, the production cost can be reduced to a minimum. Rolls combination is designed for easy adjusting the clearance between the rolls and the die. With different raw materials, appropriate clearance will help rolls work and achieve the maximum capacity. Sizes of pellets are controlled by hole diameters of pellet dies and the compression ratio of the die is crucial to the high quality of pellets and production throughput.

After the pelletizing process, the wood pellet is hot. Cooler lowers the temperature of the hot pellets to ±5 °C of room temperature and reduces the moisture by using ambient air. Cooling would extend the shelf life of the wood pellet.

Impurity and dust sieve

All pellets will go through a vibration sieve to remove any irregular pellets or dust.

Bagging and sealing system

Weighing cell and bagging machines put pellets into bags with chosen quantity and seal the bags for storage. Finished products can also be loaded by trucks or in container bags.

Biomass pellets mixed with coal

Features and Benefits of IDAH Process Design and Equipment

IDAH firmly believes in a strategy of design fit for purpose. We recognize the constraints our customers face with rising ingredient costs, energy costs, and overheads costs, yet in the face of these challenges, it is still expected that high-quality products be supplied into a very competitive market. Our design philosophy is to work continuously to refine and improve processes and equipment to maximize the success of our customers. The following describes some of the features and benefits resulting from this philosophy.

Rugged 24/7 Design

We design our equipment for continuous operations and fulfill the expectation for minimal downtime. Our mission is to see our equipment still working years after installation, with only maintenance required being routine maintenance caused by normal fair wear and tear.


Two perspectives are influencing the formulation: culturing performances and efficiency of the machinery. For example, choose the right wood source is essential. Inappropriate wood sources will lower the steam incorporation level and causes jams at the pellet mills. Fat and moisture content play inseparable roles in the hammer mill and pulverizer throughput.


The independent drive on each shaft of the IDAH twin shaft lowers power consumption and noise. The paddles' reverse rotation allows completely emptying the chamber. The misting steam and water injectors further improve conditioner performance. The following conditioner system used steam jacketed (or heat jacketed) to create a homogenous mix with little to no free water. Insufficient pre-conditioning will cause cracks on the pellet surface and creating dust fines.


The counterflow cooler is used for cooling pellet and extrudate. Warm (hot) pellets get into the cooling chamber, the suction fan will transport out the air inside the chamber, and fresh ambient air will enter the chamber from the bottom, promoting pellet cooling action. When pellets are accumulated and touch the high-level limit sensor, a pneumatic discharge swivel valve will operate immediately to discharge the products. Counterflow air heat exchange ensures to achieve high cooling efficiency.

Wood pellet factory

Specification of Pellet Mills (for Wood Pellets)

Model PM-42RB PM-53RB PM-635RB
Main Motor (HP) 150 250 350
Operation Capacity1 (t/h) 0.4-0.6 1.3-1.5 1.8-2.0


1) Wood Pellets, pellet die hole size Ø 8.0 mm, moisture content < 12%, oil content <7%


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