Control of gas emissions inunderground coal mines.pdf

International Journal of Coal Geology 35Ž. 1998 57–82
Control of gas emissions in underground coal mines
Klaus Noack )
DMT-Gesellschaft fur¨¨¨ Forschung und Prufung mbH, Institut fur Bewetterung, Klimatisierung und
Staubbekampfung,¨ Franz-Fischer-Weg 61, Essen, Germany
Received 2 August 1996; accepted 24 February 1997
Abstract
A high level of knowledge is now available in the extremely relevant field of underground gas
emissions from coal mines. However, there are still tasks seeking improved solutions, such as
prediction of gas emissions, choice of the most suitable panel design, extension of predrainage
systems, further optimization of postdrainage systems, options for the control of gas emissions
during retreat mining operations, and prevention of gas outbursts. Research results on these most
important topics are presented and critically evaluated. Methods to predict gas emissions for
disturbed and undisturbed longwall faces are presented. Prediction of the worked seam gas
emission and the gas emission from headings are also mentioned but not examined in detail. The
ventilation requirements are derived from the prediction results and bination with gas
drainage the best distribution of available air currents is planned. The drainage of the gas from the
worked coal seam, also referred to as predrainage, can be performed without application of suction
only by over or underworking the seam. But in cases where this simple method is not applicable
or not effective enough, inseam-boreholes are needed to which suction is applied for a relatively
long time. The reason for this is the low permeability of deep coal seams in Europe. The main
influences on the efficiency of the different degasing methods are explained. Conventional gas
drainage employing cross measure boreholes is still capable of improvement, in terms of drilling
and equipment as well as the geometrical borehole parameters and the operation of the overall
system. Improved control