Explosive dust at Imperial Sugar Killed 14 workers
So how does dust combust?
Often the solids that these dusts came from take effort to burn, or in the case of metals, don’t burn at all. Yet when these materials are ground into small particles they create a combustible dust. In fact, the smaller the size of these particles the more explosive they become.
When dust removal is not performed and dust is allowed to accumulate within an enclosed area it may settle in corners or flat surfaces and not seem like much of an issue. However, many dust fires and explosions have occurred when something disturbed this resting dust and ignited it. The dust becomes explosive when it is mixed with oxygen and forms a dust cloud. When an ignition source is added to this cloud it has all the elements it needs to combust, with severe consequences for anyone in the area.
When dust is allowed to accumulate it most commonly collects in places high up where it won’t be disturbed, such as rafters or pipes near the ceiling. What happens in many of the industrial dust explosions is that there is a small initial explosion when dust on the ground is disturbed and ignited. This causes a shock wave to go through the building, disturbing the dust that was sitting near the ceiling. This dust then drifts down into the air, creating a much larger cloud, which causes a much larger explosion.
This is why regulations state that even dust levels as small as the height of a paper clip, or 1/32nd of an inch, are considered a dust explosion hazard. It is also why standard cleaning methods aren’t useful in managing explosive dust; regular vacuums or air hoses just stir up the dust and create a larger hazard. Hughes Environmental uses grounded, explosion proof vacuum cleaners to ensure that the dust remediation is performed safely and efficiently.