Gas Emission Prediction and Control in Deep Coal Mines

Abstract

Taiheiyo Coal Mine is located in Hokkaido, the North Island of Japan. This coal mine is an undersea coal mine and produces fuel coal with an output of 6000 t/d. The average mining depth below sea level and gas make per clean coal tonne is 660 m and 20 m3/t, respectively. The future mining level is more than 700 m below sea level and the future planned coal production is about 10,000 t/d from a longwall face. Gas control is the most important factor to realise the large coal production in the future. In order to establish a gas control plan and to evaluate the adequate countermeasures against gas make in the underground, the following studies were carried out. • Permeability is the most important parameter, which determines the amount of gas make. In order to get the exact value of permeability of the coal seam, well tests were carried out and the permeability was determined. • Gas makes during the roadway drivage and the longwall mining were calculated by using simulators COALGAS and ROOFGAS + FLOORGAS. Gas recovery by in-seam horizontal gas drainage boreholes was calculated by changing the spacing. • Based on the above results, the optimum gas drainage methods were proposed to fulfill the regulations of the gas concentration in the ventilation air.