NO PERSONAL INJURIES.APPROX 10:30 AM KILN COAL MILL WIGH SCALE BELT WAS ERRATIC AND WAS STARTING AND STOPPING INTERMITTENLY. ELECTRICAN TO CHECK THE BRUSHES ON THE DRIVE MOTOR FOR THE WEIGH SC ALE BELT. 10:45 AM WAS IGNITION OF COAL DUST SOMEWHERE WITHIN THE COAL MILL SYSTEM CAUSING AN EXPLOSION WITHIN THE SYSTEM WHICH CAUSED THE COAL MILL SYSTEM RUPTURE DISC TO RUPTURE. THE COAL M