The loose material (3) is contained in a circular vessel (2) which has an internal dia. which widens in the direction of a circumferential radially inwardly open groove (5). The groove is indented in the wall and has a cross-section enclosing the cross-section of particles with slight play. The groove is broken in at least one point of the circumference by a sluice device through which it is connected to the discharge device (4).The loose material is exposed to the action of a flow medium (7) such as air rotating in the vessel so that it can be rotated by this flow medium parallel to the groove. The vessel is coated inside with a sound-damping layer. The groove is restricted on the side opposite the conical expansion of the vessel by a circumferential impact wall (8).
