Protection and Mitigation From Dust Explosions
Much research has been carried out in Europe and elsewhere to understand how to control these dangers, but explosions still occur. The alternatives for making processes and plants safer depend on the industry. In the coal mining industry, a methane explosion can initiate a coal dust explosion, which can then engulf an entire pit working. Stone dust is spread along mine roadways, or suspended from trays in the roof, so as to dilute the coal dust raised ahead of the combustion zone by the shock wave, to the point where it cannot burn. Mines may also be sprayed with water to inhibit ignition. Some industries exclude air from dust-raising processes, known as "inerting". Typically this uses nitrogen, carbon dioxide or argon, which are incombustible gases and so inhibit combustion. The same method is also used in large storage tanks where flammable vapors can accumulate. Usage of oxygen-free gases, however, brings a risk of asphyxiation of the workers.
Good housekeeping practices, namely eliminating the build-up of deposits of combustible dust that may be disturbed and lead to a secondary explosion, also help mitigating the problem.
Best engineering control measures which can be found in the National Fire Protection Association (NFPA) Combustible Dust Standards include:
- Oxidant Concentration Reduction
- Deflagration venting
- Deflagration pressure containment
- Deflagration suppression
- Deflagration venting through a dust retention and flame-arresting device
Read more about this topic: Dust Explosion
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