Fig.1 Explosion pentagon
Risk of Coal Dust Explosion and its Elimination
Lack of one of the elements of the pentagon or braking connection between them excludes the explosion’s appearance. In the case of the underground coal mine this model says that:
Risk of Coal Dust Explosion and its Elimination
Appearance of explosion requires the simultaneous appearance of five factors, forming the so-called explosion pentagon. (Figure 1)
combustible (coal dust) exists by its nature and in the explosion the coal dust participates,
oxidizer is atmospheric air, ignition sources results from mining technology,
Unit 10 Risk of Coal Dust Explosion
and its Elimination
Risk of Coal Dust Explosion and its Elimination
The phenomenon of a coal dust explosion has been known since more than 100 years. Almost 100 years ago the Courrieres disaster, costing 1099 lives took place. Other tragedies followed and continue to occur. We would like to be good prophets and tell that the coal dust explosion hazard is over, but experience and statistics tell us that explosions have occurred and will continue to occur. The question appears − is the lesson of many disasters not learned? Do they result because of lack of knowledge and protection means? What is the cause of the biggest mining hazard?

Risk of Coal Dust Explosion and its Elimination
we want to consider what really should be done from the point of view of mining technology to avoid a coal dust explosion. The Courrieres disaster appeared to be a milestone because it showed the dominating role of coal dust in the mining explosion- the importance of the presence of the firedamp, even though as an explosion factor, it is not necessary for explosion to occur. To answer the above questions the simple, general model of an explosion of any flammable substance is very useful. This model relates to all explosion phenomena with combustion, not only in underground mining.
Risk of Coal Dust Explosion and its Elimination
Honest answer for these questions is a simple one − knowledge of coal dust explosion causes, how it occurs, and how to avoid it which knowledge − wise is almost complete. But there are troubles with use this knowledge in everyday mining practice. Investigations of separates cases show that breaking of elementary safety rules always caused the explosion. This was proved in the recent catastrophes in Poland (Cybulski 2002) and abroad (McPherson 2001). The general conclusion of such investigation is need for simple and reliable protection systems.