A CEMENT KILN DIRECT-FIRED COAL SYSTEM EXPLOSIONVENT RUPTURED DURING OPERATION. NO INJURIES OR DAMAGE OCCURRED APART FROM THE MILL. SUFFICIENT COAL TO RUN FOR 7 MINUTES REMAINED IN THE MILL SO THE EQUIPMENT WAS KEPT OPERATING. OPERATING TEMPERATURES, DRAFTS, ETC., REMAINED NORMAL. TWO OR THREE MINUTES LATER, BEFOR FEED COULD BE RESUMEDCOAL DUST IGNITED, RUPTURING THE EXPLOSION VENT