To provide a device for treating a particulate material whose size ranges as wide as possible.

The device for treating a particulate material (80) has a processing chamber (13) for holding and treating the material (80) therein. A base (22) of the chamber (13) comprises a plurality of guide plates which are arranged to each overlap another in turn on the different level to rest on top of the adjacent lower one. Between the guide plates are disposed slots through which processing air (78) can be directed into the processing chamber (13) by an essentially horizontal component action. The device further comprises a height adjuster (72) which interacts with the guide plates and thereby the space between the guide plates and consequently the height of the slots are made variable.