Grauwvuur is a term used primarily in Flanders for a coal dust explosion: the exploding of coal in a coal mine or in areas where coal dust is present, such as storage sites. Grauwvuur has the same effect as a mine gas explosion. Explanation Reconstruction of a mine in the Minepot Waterschei with the roof bins filled with water to prevent the spread of gray fire
Activities in a mine ensure a presence of coal dust. Gravity requires a proper percentage of carbon dust in the air and an ignition. Thirty-three grams of coal dust and thirty percent volatile constituents in a cubic meter of air are sufficient for the generation of gray fire. The igniter is often a mine gas explosion or the flame of the explosives used, among other things, at the front of a steel door.
Grauwvuur is able to completely destroy a mine. The blow of an explosion causes additional carbon dust so that the ignition can continue and a chain reaction arises. Zwartberg coal mine miners got involved in 1952.
The nature of the carbon dust explosion is different from that of mine gas. Prevention
Fighting dust by spraying with water is part of the solution. Mining entrances are closed to prevent the feared chain reaction. Initially, one chose to place easily tilting shelves covered with ground limestone. The limestone spreads through an explosion which decreases the concentration of coal dust. Thin-walled water bins, suspended on the roof of the corridor (see photo) burst upon a blast; They also dilute the concentration of dust and lower the temperature. Spraying the corridors on dust-sensitive places with powder limestone is another option. Also see
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