An impact mill (10) has an inlet (12) for material to enter the mill, an impact mechanism (16, 50) arranged to rotate about a rotation axis and being operable to pulverise the material after entering through the inlet, and an outlet (154) for discharge of pulverised material. Blockage sensors (Bj), vibration sensors V, torque sensors Tn, temperature sensors and proximity sensors may be selectively incorporated into the mill.

A roller flap position correction mode can be activated manually or automatically. In the roller flap position correction mode, the position of the rear roller flap is optimised so that an accumulation of material is largely avoided. The control device of the roller flap adjustment device is designed in such a way that in the roller flap correction mode, the floating position of the rear roller flap is cancelled in a first step and the rear roller flap is pivoted upwards from a first pivoted position into a second pivoted position. In a second step, the floating position is set again, so that the rear roller flap assumes a third pivoted position in which the lower edge of the rear roller flap rests on the ground. The roller flap position correction mode may provide multiple roller flap position correction cycles within a predetermined time interval after beginning the roller flap position correction mode or within a predetermined distance covered after beginning the roller flap position correction mode.