How Industrial 8mm Pellets Are Made: Inside the Mill
A step-by-step look at industrial pellet production: debarking, chipping, drying, hammer milling, pelletising, cooling, screening and quality control.
An industrial pellet plant is a drying and densification line. Wood goes in at 45–55 % moisture and low bulk density; pellets come out at 7 % moisture and roughly 650 kg/m³. Here is each stage and where quality is won or lost.
1. Reception and debarking
Roundwood is debarked when producing low-ash grades. Bark carries most of the mineral content, so this single step decides whether you can hit ≤ 0.7 % ash or only industrial spec.
2. Chipping and screening
Material is reduced to uniform chips and screened to remove stones, sand and metal. Contamination here destroys dies later and shows up as ash in the certificate.
3. Drying
Belt or drum dryers bring moisture to 10–12 %. Over-drying wastes heat and produces brittle pellets; under-drying causes poor lignin bonding and low durability.
4. Hammer milling
Chips are ground to a fibre size below roughly 4 mm — smaller than the die hole for 8 mm pellets. Particle size distribution directly controls durability.
5. Pelletising
A ring die and rollers force the fibre through 8 mm channels at 90–130 °C. Friction heat plasticises lignin, which sets as the pellet cools. Die compression ratio is tuned per species.
6. Cooling and screening
Counter-flow coolers bring pellets to ambient temperature so lignin hardens. Final screening removes fines before bagging or bulk loading.
7. Quality control
Hourly sampling for moisture, durability, ash and length distribution, with retained samples per production lot. Ask any supplier whether they retain lot samples — if not, claim resolution is guesswork.
Pellet Industries ships ENplus A1 and industrial biomass pellets worldwide in 15 kg bags, big-bags, and bulk vessel loads.
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