A review of coal mine fire extinguishment methods

David S. Hallman; David S. Hallman

doi:10.48130/emst-0024-0004

Figures (12) Tables (1)

Figure 1.
Fire triangle.
Figure 2.
Surface changes resulting from an underlying mine fire that allow the fire to breathe. (a) Ground fissures and slumping, (b) subsidence fissure venting hot combustion gases, (c) large open fracture, (d) microfractureing, (e) baked rock commonly known as 'clinker, scoria or red dog', (f) and (g) Pyrometamorphic paralava 'sponge' formations created by superheated exhaust vents.
Figure 3.
Coal mine fire beneath rugged terrain in the Grand Hogback at Newcastle, Colorado, USA. (a) After recent snow and (b) with thermal infrared imagery. The rock strata dip to the left at 50 degrees.
Figure 4.
South Canyon West coal mine fire, Colorado (USA) during snow. The coal bearing strata and mine workings plunge to the left at about 50 degrees and would be impossible to isolate.
Figure 5.
Surface water infiltration basins over a shallow mine fire.
Figure 6.
Examples of mine fires venting hot combustion gases through soil cover. (a) Coal tar residue condensed from gases upon venting through soil desiccation cracks; (b) and (c) Hydrocarbon and coal tar residues from venting through rocky cover material; (d) Sulphur crystals from H₂S emissions through rocky cover soil.
Figure 7.
Large shrinkage or 'mud' cracks in fine grained sediments upon drying.
Figure 8.
Grout injection holes venting combustion gases at the Scotch Hill mine fire, Newburg, West Virginia, USA.
Figure 9.
IHI No.3 coal mine fire, Colorado (USA) which continues to burn vigorously despite multiple extinguishment efforts that included surface sealing, grouting and excavation.
Figure 10.
Starting with pit run sand, water is added to raise the moisture content to 1%−2% below field moisture content, then preformed foam is added to about 30% vol/vol solids to produce a highly flowable, pumpable slurry mixture.
Figure 11.
Foam transported sand backfill being placed in a room and pillar coal mine.
Figure 12.
Verification boring results showing tight contact between the final sand backfill and the roof or crown of the underground void opening.

Method	Mine condition		Depth	Surface Impact	Relative cost	Comments
Method	Active	Abandoned	Depth	Surface Impact	Relative cost	Comments
Bulkheads and stoppings	Yes	No	Any	None	Low	Good for reducing spontaneous combustion and recent fires in active mines; used with inerting
Inerting	Yes	No	Any	Little to none	Low to moderate	Good for reducing spontaneous combustion and recent fires in active mines; leakage an issue
Ventilation control*	Yes	No	Any	None	Low	Requires active ventilation system
Surface treatment**	Yes	No	Any	None	Low	Primary use is to inhibit spontaneous combustion
High-expansion foam	Yes	Limited	Any	Little to none	Low	Good for recent fires in active mines
Excavation	Limited	Yes	Shallow	Very high	Very high	Can't be used for developed areas, rugged terrain or deep fires
Isolation	No	Yes	Shallow	High	High	Fire is left to burn indefinitely
Surface seal	No	No	Any	High	Low	Low cost but also low effectiveness
Remote seal	Yes	No	Shallow	Little to none	Low	Ineffective
Barriers	Limited	Yes	Any	Little to none	Moderate	Largely ineffective
Hydraulic backfill	No	Limited	Any	Little to some	Moderate	Effective for small mines in flat seams; large volumes of water required
Pneumatic stowing	Limited	Limited	Any	Some to none	Low	Limited applicability except in active mines; primarily used for subsidence control. Beneficial use of waste.
Grouting	Limited	Yes	Any	Little to some	High	Grout is subject to flash setting and thermal degradation
Multi-phase Foam and gel***	Yes	Yes	Any	Little to none	Moderate	Material dehydrates and cracks with time, limited duration of protection
Cellular Grout****	Yes	Yes	Any	Little to some	High	Good for spontaneous combustion in active mines; Portland cement prone to break down under sustained high temperature
Foam-transported backfill	No	Yes	Any	Little to some	Moderate	Wide range of backfill materials possible, less cost than grout, un-tested on a coal fire
* Includes dynamic pressure balancing as well as reversal. Includes chemicals, powders or other coatings. * Includes foamed gel, and foam stabilized with fly ash, nanoparticles, etc. **** Cellular concrete, foamed concrete, inorganic solidified foam (ISF), inorganic curing foam (ICF) and cement-based foam material (CBFM).

Table 1.

Summary of mine fire control methods.