EMPLOYEE WAS IN THE PROCESS OH SETTING UP A CEMENT MIXER ON THE WALKWAY ABOVE THE PREHEAT FURNACE. AS THE MIXER WAS TURNED ON THE ROTATION OF THE MIXER WAS BACKWARDS CAUSING THE DRUM TO MOVE F ORWARD. THE FORCE OF THE MOVEMENT BENT THE SAFETY CATCH CAUSING THE DRUM TO DUMP. THE DUMP HANDLE STRUCK HIM IN THE RIGHT ARM JUST BELOW THE BICEP. PHYSICAL THERAPY STARTED ON 3-22-00.