Paul Janzé – Advanced Biomass Consulting Inc.
Introduction
Some materials such as wood pellets are quite fragile and tend to break up when handled. 
Wood pellets are manufactured from small wood particles, generally <3.0mm (<1/8″), which are compressed in pelletizers into small cylinders 6-8mm in dia. x up to 50mm long. Pellets are held together by the binding action of the lignin that is naturally present in the wood fibre, acting under pressure. From the moment they exit the pelletizer and fall into the receiving conveyor, the pellets start to break up. At every conveyor transfer point, in bucket elevators, screw and chain conveyors, falling into bins, loading into trucks, railcars or ships, they degrade some more. Every time they are handled by crane or mobile equipment, they break up a bit more into their constituent parts. The best way to reduce product damage and small particle generation is to handle the pellets as gently as possible. Falling >30m (100′) into a silo results in high velocity impact forces, breakage and dusting. Consequently when faced with the problem on a recent project, we developed a spiral / helical chute which allows pellets to slide rather than freefall to the bottom of a silo.