Ball mills. Michael M ller-Pfeiffer Research Institute of the Cement Industry D sseldorf Seminar Grasim, 28 February 2007 Structure. 1. Introduction 2. Movement of grinding media in a tube mill 3. Ball charge and ball filling level 4. Components of ball mills linings, diaphragms, mill inlet, drive, bearing 5. Mill ventilation, water injection and grinding aids 6.