MINNESOTA CORN PROCESSORS

No employees injured in grain dust explosion

On January 14, 1988, two employees were near a feed house making general equipme nt checks. A Carter Day dust collector, which was attached to a Champion 125-hp hammer mill, blew its explosion door outward, forcing ignited grain dust into th e grain leg. The ignited grain dust continued up and out into the grain storage bins through a drag auger, causing the steel bin tops to blow off. The metal roo f and side walls blew out. The two employees heard a small explosion before a ba ll of flames shot toward the ceiling, fueled by a second explosion. However, no employees were injured. Subsequent inspection of the tramp metal magnets found t hem to be clogged with excess metal contaminants. It appears that tramp metal sl id by the magnets into the hammers, resulting in sparks that landed in grain dus t. The 20-hp, 4000-cfm fan blower spread the sparks and dust through a 12-inch-d iameter pipe and into the Carter Day dust collector. The ideal air concentration to support a grain dust explosion was present, combined with sparks and dust. A second explosion was supported and ignited by the first explosion when excess g rain collected in the dust collector. The tremendous heat caused rapid expansion that blew the wall and ceiling panels outward.