Abstract: Employee #1 and two coworkers were working in an 8 ft by 8 ft by 6 ft ventilated soundproof room (1100 cfm) where a hammer mill drives granulated sugar through a screen to produce fine powered sugar. The process was enclosed, but not ventilated, though the equipment was in a ventilated room. An explosion occurred within the pulverizer and may have caused a secondary explosion in the soundproof room, which was extensively damaged along with the pulverizer. Two employees left the room seconds before the explosion because they feared the outcome of the noisy bearings. Employee #1 sustained a sprained leg muscle. Extensive sugar dust accumulation on the floor and work surfaces was noted. The ignition source appears to have been an overheated bearing, which shattered.