Mitigating Dust Explosion Risks In Solid Powder Processing

Dust explosions are a risk in many processing environments but they pose a special risk when the product being processed is a fine, solid powder. Many materials, such as organic solids (sugar, wood, grain, etc.) and some metals (such as aluminum and magnesium), while being merely combustible to various degrees in large sizes, become explosive when sized very finely and dispersed in dense enough concentrations. Combustible substances with an average particle size smaller than 420 micron are generally considered to be explosive.

A 2006 investigation by the U.S. Chemical Safety and Hazard Investigation Board identified 281 combustible dust incidents between 1980 and 2005 that resulted in at least 119 fatalities and 718 injuries in the United States. These incidents included seven "catastrophic dust explosions" in the decade preceding publication of the investigation report, which involved multiple fatalities and "significant community economic impact". Dust explosion incidents continued to occur after this report was published. A particularly notable recent incident was the explosion at the Imperial Sugar Refinery in Port Wentworth, Georgia in February, 2008, which killed 14 people and injured 36.

The apparent lack of reduction in the number and severity of dust explosion incidents over the years has propelled industrial regulations around the world to grow more stringent with respect to dust explosion safety. Manufacturers are currently facing the challenges of complying with these new regulations. This paper will explain the basic mechanics of combustion and explosion, outline the different dust explosion properties that are commonly measured, and present different methods of minimizing dust explosion hazards that are compliant with the new regulations and that are relevant to companies working with solid powders.