New system that grinds with air

Swedish machinery maker Franssons, a partner of AVEBIOM, used Expobioenergía to present the innovative HK Green mill for green and humid wood that “grinds with air”. The company has spent months working hand in hand with a Swedish pellets factory in an attempt to decrease the main cost in the process: drying the raw material chips. The result is this mill for fine materials from humid chips under 50 mm, which can reduce them down evenly to up to 7 mm and so improve the efficiency of particle drying.

The mill has an integrated flat fan that can propel a volume of 6000 m3 of air, which in turn pushes the material against the sieve using hammer or grinding plates. The air turbulence helps the particles collide with each other, which contributes to the grinding process.

The hammers can be positioned four times before being discarded and the flat rectangular sieves are easy to change so it is cheaper to maintain and to swap if different granule output sizes are needed. The fan wheel is made of HARDOX, a certified tough steel. And all the equipment has ATEX certification, which means it is approved for working safely in atmospheres with an explosion risk.

The material enters on a frontal conveyor. A venturi tube makes the heavier stones fall and a magnet removes metallic elements. With an outlet cut into the venturi tube a hose can be connected to vacuum and clean.

This grinder is sold with powers of  75-110, 90-132 and 132-200 kW, with yields ranging from 1700 kg/h to 6 t/h. Potential customers include those who grind green poplar.

The price of the HK 35, shown in the exhibition, is €70,000. The company claims that savings made in drying will pay this back in a year.

Further information: www.bioenergyinternational.es