The Practice Of Methane Drainage In Japan

Japan has produced 14-16 million tons of coal per year in the past several years. About half of the production comes from eight coal mines in the Ishikari coal field, Hokkaido. Most of the gassy coal mines are in this field and the average mining depth of these coal mines has already attained about 700 m from the surface. Therefore, most of the coal mines have suffered from occurrences of coal and gas outbursts. To prevent outbursts and to reduce ventilation air, gas drainage has been carried out at all of these coal mines and these have had successful results. However, the methods of gas drainage differ from mine to mine. In this report, an outline of the main methods of gas drainage are described.