The Characteristics of Collapse Columns in Duanwang Minefield and their Influences on Gas Emission Quantities of Coal Faces

Abstract

Duanwang Coal Mine is located at north of Qinshui coalfield in Shanxi province, China, which gently inclined and thick seams have been mined. Authorized production capacity of the coal mine is 1.8Mt/a. With the increase of mining depth, the mine gas emission quantity increased. Karst collapse columns are very developed in the minefield, and the phenomenon of abnormal gas emission always occurred at the coal face and driving gateway around the collapse columns, then the mine became high gassy one from low gassy mine. Using field measurement and theoretical analysis methods, the following conclusion can be drawn. Karst collapse columns have significant influences on gas emission of the coal face and driving gateway. Here are large amount of free form gas into and around the collapse columns, the collapse columns were disclosure while driving gateway, a large amount of the free gas into collapse column would be instantly released, which caused abnormal gas emission at driving gateway, even leading to gas density exceeding limitation by Coal Mine Safety Regulation of China. However, during mining area of the collapse columns, gas emission quantity at coal face was relatively smaller.