Abstract: At approximately 1:00 p.m. on June 12, 2000, Employees #1 through #6 were transferring a mixture of plastic fines and lubricants.; the additives were explosive when in a suspended state, as per the Material Safety Data Sheet (MSDS). This transfer was performed by dumping the mixture from the mixer into a series of screw conveyors and then dropping the mixture from the top conveyor into a large metal silo. The transfer was approximately 75 percent complete when there was a small explosion in the #3 silo. The explosion shook the entire building and suspended large quantities of dust into the air. This dust then ignited and produced a large but quick dust explosion. The explosion blew out the walls and 50 percent of the roof. All of the six silos were damaged. Employees #1 through #6 sustained injuries ranging from first-, second-, and third-degree burns to shock, and Employees #1 through #3 were hospitalized overnight. The building was not designed as a Class 2, Division 1 location. None of the covers were dust tight, and there were no fire dams (chokes) to prevent the fire and explosion from spreading to other parts of the facility.