Methane emission from flooded coal seams in abandoned mines, in the light of laboratory investigations

Emission of methane from flooded unexploited coal seams Field experience from the flooding operations of the abandoned gassy mines, shown that the presence of water and related to it hydrostatic pressure limits the desorption and migration of methane from the unexploited seams destressed by mining. However, in the scientific literature, there is no information, being of importance from the point of view of mining practice, on detailed description of mechanisms involved. In connection with the above, over the years 2004-2005, the INERIS Institute (France) and Central Mining Institute (Poland) carried out joint laboratory tests aimed at determining the relationships in the system “coal-gas-water”, in the context of the flooding of unexploited gassy coal seams in abandoned mines. The tests included the following main stages:- Determining sorption capacity of coal in the dry-air state through determining the isotherm of methane sorption on a coal sample taken from the analysed coal seam. Determining the sorption isotherms enables to evaluate, with considerable accuracy, the volume of gas contained in the coal for a given level of sorption equilibrium pressure, and then to determine the quantity of the desorbable gas Vdes from the specified mass of coal, at the drop of pressure up to the atmospheric pressure level (Fig. 4). Fig 4. Isotherm of gas sorption on a coal sample Research Reports of Central Mining Institute “Mining & Environment ” Quarterely N ° IV/200