Methane coal mining

Permissible or Permitted Explosives. In many coal mines there is a continual evolution of methane (firedamp) into the air of the workings. 

Electric detonators are made from aluminium or copper tubes, the latter being for use in coal mines where aluminium may lead to a possibility of ignition of methane/air mixtures. 

Delay detonators for use in coal mines must be constructed so as not to ignite methane/air mixtures even if iired accidentally outside a cartridge of a blasting explosive. This requires a suitable selection of fusehead and the provision of the delay element in a form which will not produce large particles of hot slag on burning. In the British design the delay elements are... 

It must be remembered that methane can be liberated in a coal mine, not only in the coal itself, but in the nearby stone. It is therefore necessary to use permitted explosives, both in and near a seam of coal. Further, before any shot is fired in a coal mine, tests are made for the presence of methane in the air by means of a safety lamp. This safety lamp is the well-known Davy lamp and an experienced operator can judge the presence of methane in the air from the appearance of the flame. Tests are made... 

Gassy coal mine. A mine in which methane may be present also known as a safety lamp mine. 

Use of different fuels (coal mine methane, naphtha)... 

It is interesting to note that stratified combustible gas mixtures can exist in tunnel-like conditions. The condition in a coal mine tunnel is an excellent example. The marsh gas (methane) is lighter than air and accumulates at the ceiling. Thus a stratified air-methane mixture exists. Experiments have shown that under the conditions described the flame propagation rate is very much faster than the stoichiometric laminar flame speed. In laboratory experiments simulating the mine-like conditions the actual rates were found to be affected by the laboratory simulated tunnel length and depth. In effect, the expansion of the reaction products of these type laboratory experiments drives the flame front developed. The overall effect is similar in context to the soap bubble type flame experiments discussed in Section C5c. In the soap bubble flame experiment measurements, the ambient condition is about 300 K and the stoichiometric flame temperature of the flame products for most hydrocarbon fuels... 

Methane is produced by bacteria under anaerobic conditions in wet environments such as wetlands, swamps and rice fields. It is also produced in the stomachs of cattle and by termites. Typical anthropogenic sources are from fossil fuels such as coal mining and as a byproduct in the burning of biomass. The latter sources are considerably heavier in C than the former. Recently, Keppler et al. (2006) demonstrated that methane is formed in terrestrial plants under oxic conditions by an unknown mechanism. The size of this methane source is stiU unknown but it might play an important role for the methane cycle. 

Although fire damp/ which is mainly methane, and choke damp (carbon dioxide) are frequent causes of mine accidents, Dr. William Brownrigg learned how to make good use of them. In 1741 he communicated to the Royal Society several papers on the gases of coal mines, but preferred to withhold them from publication until he could prepare a comprehensive treatise on the subject. His laboratory at Whitehaven was provided with several gas furnaces of his own design and a constant supply of fire damp from the nearby mines. Because of his skill in foretelling explosions by the rapid fall of the barometer, mine operators often consulted him. 

Novak, T. Fisher, T. J. 2001. Lightning propagation through the earth and its potential for methane ignitions in abandoned areas of underground coal mines. IEEE Transactions on Industry Applications, 37, 1555-1562. 

Thielemann, T., Krooss, B. M., Littke, R. Welte, D. H. 2001. Does coal mining induce methane emissions through the lithosphere/ atmosphere boundary in the Ruhr Basin, Germany Journal of Geochemical. Exploration, 74,219-231. 

Williams, A. Mitchell, C. 1994. Methane emissions from coal mining. In Hester, R. E. Harrison, R. M. (eds) Mining and Its Environmental Impact. Royal Society of Chemistry, London, 97-109. 

CASH CBM CBO CBPC CC CCB CCM CCP CDB CEC CFBC CFC CFR CMM COP CSH CT Calcium aluminosilicate hydrate Coal bed methane Carbon burn-out Chemically-bonded phosphate ceramics Carbonate carbon Coal combustion byproducts Constant capacitance model Coal combustion product Citrate-dithionate-bicarbonate Cation exchange capacity Circulating fluidized bed combustion Chlorofluorocarbon Cumulative fraction Coal mine methane Coefficient of performance Calcium silicate hydrate Collision theory... 

Explosifs anfigrisouteux. French industrial explosives authorized for use in fiety coal mines,- because when used under prescribed conditions they do not ignite mixtures of methane-air-coal dust. They may be subdivided into explosifs coucbe (qv) and explosifs roc be (qv)... 

Gas, Coat Mine or Firedamp. A mixture of methane (CH4) and air, usually present in "gaseous (fiery) coal mines", such as soft (bituminous) coal mines... 

Coal mining is usually done by a method which is known as the long wall system , the details of which are already available in the literature [100]. The most important thing to remember during coal mining is that methane gas may be liberated not... 

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