Pellet Binder

Pellet production characteristics change depending on the raw material being processed, and the equipment used. Many raw materials contain sufficient natural binding properties through their lignin content. Lignin is is the natural carbohydrate, which gives biomass its strength. Some biomass materials have more lignin that others, for example wood compared to grass. However depending on the density of the raw material, and the type of equipment used, influences if the lignin can be properly utilized to form pellets. Where there isn't sufficient lignin, or the lignin cannot be utilized, supplementary binders can be used.

Low Inclusions Binders

Water and vegetable oil, among other oily waste biomass can be used as binders, however their inclusion rate has to be quite high, for example up to 30%. They also generally do not produce a pellet of sufficient density and durability, low inclusion industry standard pellet binders are more suitable. Industry standard low inclusion binders usually require only a 0.25-1% inclusion rate.

Wood pellet production compared to grass pellet production for example, is a far more energy intensive process. The wood generates increased resistance as it passes through the die, due to its increased density. Therefore industry standard binders can also be used to lubricate the die during wood pellet production. Lubricating the die has multiple benefits in the pellet mill. Lubrication can increase productivity, reduce wear on disposable parts and increase wood pellet quality.

Using low inclusion binders to also lubricate the pellet mill die during production has multiple benefits. One of the advantages is increased productivity through reduced resistance through the die. Even though resistance is related to compression, pellet quality can still be maintained through the additional binding properties of the binder. The lubrication can also increase die and roller life within the pellet mill. Also the reduced resistance also reduces energy consumption during production. With an increased productivity and reduced energy demand and increased life of consumable parts, the additional cost of the binder is easily recovered.

As stated many raw materials do have sufficient natural lignin to act as a pellet binder, however releasing that potential in a small pellet mill can be difficult. Utilizing lignin as a binder relies on sufficient heat and pressure generated in the process. This may not be an issue in the small pellet mill when processing grass, as it much easier to heat the lignin to the required temperature as most grass has a low density. Producing pellets from wood however can be much more difficult, and therefore requires a binder.

PelHeat Wood Pellet Production Guide

At PelHeat we have many years of experience in pellet production, and we provide a pellet production consultation service. The PelHeat guide download will show you how to make wood and other fuel pellets.