Complex Technology of Underground Coal Gasification and Coal-Based Methane Recovery Using Geodynamic Zoning
The article describes the complex technology of coal methane recovery, which involves underground coal gasification of lower beds in series of gas-rich strata liable to rock-bumps, coal based methane recovery and mechanized coal mining. Geodynamic zoning
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Abstract: The article describes the complex technology of coal methane recovery, which involves underground coal gasification of lower beds in series of gas-rich strata liable to rock-bumps, coal based methane recovery and mechanized coal mining. Geodynamic zoning is used for selection of places for well drilling. The application of the suggested technology enables to solve a range of tasks, such as ̵ unloading of workable beds and reduction of their rock-bump hazard due to protective seam burnout; ̵ increase of workable beds degasification due to unloading; ̵ increase of workable bed methane desorption rate due to conductive and partly convectional heat transfer through interbeds; ̵ reduction of workable bed coal strength and rock-bump hazard by passing-through combustion gases (CO and especially СO2); ̵ degasification of coal bearing layers and sublayers of interbeds due to their partial burnout during gasification and accelerated degassing during intensive heating; ̵ increase of gasification products heat value due to their diluting with methane recovered from upper beds degasification; ̵ reduction of methane outburst to the atmosphere, which has greater greenhouse effect in comparison to carbon dioxide.
Key words: series of coal strata, gasification, complex technology, degassing, geodynamic zoning, methane. The significant amount of ultimate coal reserves is located in the series of gas-bearing strata liable to rock-bumps and could not be recovered with conventional mining methods. During ascending exploitation mining the extraction of coal from the lowest seam is quite challenging or impossible due to high geodynamic risks. During descending mining the overworking has low impact on processes of
Ó Springer International Publishing Switzerland 2016 V. Litvinenko (ed.), XVIII International Coal Preparation Congress, DOI 10.1007/978-3-319-40943-6_77
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unloading and gas emission from lower beds, thus mining can be done only up to the first thick interbed or until reaching very hazardous beds. The conventional method of mining series of strata prone to rock- or outbursts involves initial extraction of protective seam. [1, 2]. The advantages of this method are parallel extraction of protective and main seams during the period of the highest unloading and its maximum effect due to relatively small advances. However, firstly, when mining methane rich coal beds the extraction of protective seam using oil mining becomes highly risky in every aspect – outbursts, rock-bumps, intensive gas emission, and methane explosion risk, which prevents protective seam extraction under extremely hazardous conditions at great depths. Secondly, the non-pillar extraction is quite challenging within the framework of conventional mining methods, and if there are difficult conditions in the protective layer, the mining process could not be carried out at all. The alternative to non-pillar extraction is creation of yield (long-holed) pillars, but even they cause high-pressure zones in the overlying beds t
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