EE WAS CLEANING FEED SHELF OF KILN: OPENED DOOR ON THE S/E SIDE OF SHELF. A WALL WAS BUILDING UP ON THE EAST FACE & DECIDED TO BAR IT DOWN WITH A SCRAPER BAR. WHILE WORKING ON THE BUILD-UP A CHUNK BLEW OUT & WENT UNDER VISOR THE CHUCK HIT MICROPHONE & FELL DOWN SHIRT CAUSING 2ND & 3RD DEG BURNS ON NECK & CHEST. LIGHT DUTY UNTIL RELEASED BY DR.