Emergence

A natural methane-air mixture is present in every hard coal deposit. Mine gas emerged from organic substances during the process of incoalation about 300 million years ago. Utilisable methane concentrations number between 25 % and 90 %. The colour- and odourless mixture isn't toxic, but in cases of methane concentrations between 4 % and 15 % it is highly explosive.

After exhaustion of the hard coal deposit the mine is shut-down. However, even after shaft plugging gas discharges from the carbon mass through cracks and crevices. Piping inserted into the drift further on is used for the targeted gas evacuation. Methane capacity of coal isn't the same in all seams. Basically gas and bituminous coal contain more methane than hard, steam and anthracite coal. Methane concentrations in local deposits amount to up to 25 m³/t of coal; globally there are seams with up to 200 m³/t of coal.