EMPLOYEE WAS USING A AIR LANCE TO REMOVE BUILDUPFROM THE PREHEAT TOWER DUCT. HE HAD COMPRESSED AIR RUNNING THROUGH THE LANCE AND WAS USING IT'STIP TO KNOCK HOT BUILDUP FROM THE POKE HOLE DOOR HE HAD OPENED. A HOT PIECE OF MATERIAL FLEW BACKAND LODGED IN HIS OUTER RIGHT EAR, HAVING MISSEDBEING DEFLECTED BY HIS FACESHIELD. THE BURN BECAME INFECTED & MEDICATION WAS PRESCRIBED.