Uncontrolled Fires in Coal and Coal Wastes
AUTHOR: Simon Walker
DATE: April 1999
Fire remains one of the principal hazards facing all stages of the coal production and transport cycle. Most of the world's major coalfields have experience some incidents, the prevalence depending on factors such s the type of coal being produced, the mining method used, and the effectiveness of washing plants in recovering coal from waste. Under appropriate conditions, the natural oxidation of coal accelerates rapidly, leading to self-heating and spontaneous combustion. The cost of controlling fires caused by spontaneous combustion can be very high, with incidents occasionally leading to the abandonment of a mine, or to the loss of cargos at sea, if control efforts prove unsuccessful. Mine and washer waste can also be susceptible, leading to long-term emissions of smoke, dust, gases and acidic run-off from old spoil heaps. Evidence further indicates that natural seam fires have occurred in various parts of the world over much of the last one million years, triggered by phenomena such as lightning strikes and bush fires.
This report reviews the mechanisms by which spontaneous combustion occurs during coal production, storage and transport, and in spoil piles. It addresses the incidence of uncontrolled fires in the wider geographical context, and in terms of the impact of major occurrences on the global environment. Points discussed for each stage of the cycle include the detection, prevention and control of spontaneous combustion, using case studies to illustrate specific practices.
While the majority of uncontrolled fires present little more than local inconvenience, a few, including those currently burning in parts of India and in large areas of northern China, make a significant global impact. The report concludes by drawing attention to efforts already being made to combat these outbreaks, and highlights the need for further international involvement in tackling these major sources of uncontrolled greenhouse gas emissions.