Wood Hammer Mill
A Wood Hammer Mill can grind straw, switch grass, wood chips, corn stalks and other biomass to size and consistency prior to putting through a pelletizer. If you have timber chunks, you may need to chip the timber before putting through the hammer mill.
Chipping needs to reduce your material into smaller, uniformly sized portions. When the material thickness is larger than 10 mm (7/16“) or size is greater than 50×50 mm (2”), a wood chipper is needed to chip these materials into smaller pieces. If you have large branches, trees trunks, or split timber the cost of a chipper will be quite high as these are serious bits of equipment.
The hammermill is then used to further crush these small pieces into particles of less than 3 mm or 1/8 inch diameter. The small scale hammer mill seen above is essentially a steel drum containing a vertical or horizontal cross-shaped rotor on which pivoting hammers are mounted. The hammers are free to swing on the ends of the cross. These high speed hammers essentially beat the biomass apart until it fits through the openings of a metal screen. The size of the openings in the screen determines the final size of the processed biomass. They have a reasonably high throughput and are very simple to operate. They are also very noisy and can create a significant amount of dust with most dry biomass.The hammer mill pictured here is made by the Nanjing Pellet Mill Co. Ltd in China.
Making pellets can be quite an investment in the machinery required to generate your fuel. Anyone considering manufacturing their own pellets and considering a wood hammer mill would need to some hard cost analysis to ensure you are not over capitalizing. It might indeed be cheaper to purchase the pellets from a larger supplier, or perhaps a co-operative could be formed to share the costs.