Geology Reference
In-Depth Information
Incidence of Coal Fires
R
ecent studies have indicated that uncontrolled coal fires are a global problem. In addition to the inherent health
and safety problems, such fires are believed to contribute to greenhouse gas emissions. Over 1% of the global
emission of CO
2
from fossil fuels is believed to be generated by coal fires in China (Rosema et al., 1999; Stracher
and Taylor, 2004; Voigt et al, 2004).
In the United States, fires in abandoned mines and in outcrops, termed wasted coal fires, have occurred during the
past 200 years. Since 1950, there have been over 600 coal-related fires in the United States (Johnson and Miller,
1979). As of 2005, 141 fire-control projects on abandoned mine lands (AMLs) were listed on the Office of Surface
Mining Reclamation and Enforcement
s Inventory (OSMRE, 2005). This is an underestimate of the actual number
of fires because many that occur are not associated with coal mining. In the United States, most underground mine
fires are in the eastern coal-producing states. The characteristics of eastern fires vary depending upon whether they
are in bituminous or anthracite seams. Waste bank fires occur in the eastern and central states where the majority of
coal-preparation plants were located. Outcrop fires in inactive or unmined deposits are more prevalent in the
Western United States.
'
Currently, coal fires are a serious problem in the Jharia coalfield of India and the Wuda coalfield in Inner Mongolia.
Fires are also a problem in Indonesia, New Zealand, South Africa, Australia, Siberia, and other parts of the world
(Masalehdani et al., 2007; Michalski, 2004; Sokol and Volkova, 2007; Stracher, 2007; Whitehouse and Mulyana,
2004). In addition to the loss of energy resources, coal fires are a source of CO
2
and other air pollutants. They may
cause subsidence, ignite forest fires, and can create a health hazard due to airborne dust, acid gases, and potentially
toxic trace elements and organic compounds (Finkelman, 2004). Uncontrolled burning of coal can create problems
from an unpleasant atmosphere to the destruction of property to the devastation of ecosystems.
Ignition and Propagation of Coal Fires
A
s with any fire, coal fires require three elements: fuel, oxygen, and an ignition source (Figure 1.2.1). In coal
combustion, the fuel is the carbon in the coal. If combustion is considered the exothermic reaction of carbon and
oxygen to form CO
2
, written as
C
þ
O
2
→
CO
2
þ
HEAT
;
the amount of heat liberated is 93.7 kcal/mol.
Fuel
Figure 1.2.1. Fire triangle showing the three essential elements for any fire: fuel, oxygen, ignition source. From
Kim and Chaiken 1993, p. 6.
