Predegassing of Coal Seams in German Hard Coal Mines
(0) Decrease of the gas content in the worked seam by degassing before the start of winning hasproven its worth in some areas of German hard coal mines，on the one hand in order to remove the risk of gas/coal outbursts and on the other hand in order to reduce the gas inflow into thelongwall.The underground experiences of the last 30 years have led to a“hit list”of coalseams with respect to their suitability of predegassing.Trials in the DMT-laboratory and alsoresults gained in the deposit show that the suitability of a seam for predegassing depends onits rank.In seams with volatile matter of 20％～30％，high efficiency ratings are achieved asa rule，with lower ratings both in seams with lower and with higher content of volatile matter.If the rock pressure is unusually high，the efficiency rating of the predegassing is lower，even in seams which would normally be suitable for this process.Under unfavourable conditions，for example below or above residual pillars，in-seam boreholes cannot be drilled successfully andthe method is not practicable.But if the worked seam was already stress relieved，thepredegassing has an optimal efficiency.Latast investigations show，that the distance of the in-seam boreholes from one another can be extended.But in that case the time，which is necessaryto reach the same reduction of the gas content，increases considerably.
gas coal outbursts Hard Coal Mines Predegassing of Coal Seams
Erwin Kunz
DMT GmbH,Germany
国内会议
安徽淮南
英文
95-99
2007-10-25（万方平台首次上网日期，不代表论文的发表时间）