prevention and control of spontaneous combustion - Mining and

• Accumulation of loose coal on the floor adjacent to the highwall
• The specific problem of mining old workings, with the ready entry of air through exposed
bords.
The above points are equally applicable to single-seam operations or to multi-seam, open-pit
mining, where coal seams on benches may be a source of spontaneous combustion when
exposed for protracted periods.
The literature consistently points out that to prevent or combat heatings and fires the guiding
principles are based on the fire triangle (figure 1). Since the source of fuel is the coal being
mined and the potential source of heat is the oxidation of that fuel, the only effective prevention
techniques must be based on preventing air coming into contact with any coal that is prone to
spontaneous combustion. The techniques used by South African mines will be discussed later in
this report, but the most commonly discussed method in overseas literature is sealing of cracks.
The cracks may be sealed with a mechanical spraying device using fire protective coating
material. The characteristics of a typical fire protective coating should include:
• Easy spraying
• Compatibility with coal
• Not washed down by water/rain
• When applied over coal surface, it forms a uniform thin coat
• Maximum resistance to air permeation
• Good fire resistant capacity
• Coating remains intact for a long time (more than a year)
• No cracks appears in the coating material and there is no scaling from the coal surface
during blasting of the coal face
• The shelf life of coating material is more than one year.
Singh and Singh (2004) 14 used this technique in an opencast coal mine in India for a typical
bench height of 20m. The system used 0.8 to 0.9 kg/sq.m and the resultant thickness of coating
was reported to be 0.9mm after two coats. It is said that the coating remained intact even after
heavy rains and the coated zone temperature remained at ambient.
Panigrahi, et al 15 reported on inhibitors that reduce the spontaneous combustion susceptibility of
Indian coals. The following inhibitors were considered:
14 RVK Singh and V K Singh, Mechanical Spraying Device-A novel technology for spraying fire protective coating material
in the benches of opencast coalmines for preventing spontaneous combustion. Fire Technology, 40, 335-365, 2004
Kluwer Academic publishers
15 D C Panigrahi, G Udaybhanu, M D Yadav and R S Singh, Development of inhibitors to reduce the spontaneous
heating susceptibility of Indian Coals. Eight International Mine Ventilation Congress. Brisbane, Queensland, 6-8 July 2005
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