Abstract: An apparatus for treating a particulate material comprising a container, which has a base, an upright wall, extending from bottom to top, and, in an upper region, a deflecting element, to deflect the material rising up along the wall in its direction of movement in such a way that it can return again to the base, it being possible for at least the wall to be driven in rotation about a vertical axis of rotation. In the upper region of the container there is at least one container element which can be driven in rotation in the same direction as the upright wall, but with lower rotational speed, about the vertical axis of rotation.