Methane Drainage from Gassy Mines - A Global Review

Sixty countries around the world mine about 5000 million tonnes of coal annually and simultaneously produce nearly 25 million tonnes (36.8 Gm3) [One tonne of methane at a temperature of 15°C and a pressure of 760 mm of mercury has a volume of 1471 cubic meters.] of methane. Many of these coal mines are very gassy and require methane drainage prior to mining as well as during mining. In spite of significant differences in the geology and reservoir properties of the coal seams, several methane drainage techniques have found universal application. The paper describes various techniques currently in use and their efficiency in recovering methane from mines. It appears that the application of state-of-the-art techniques, developed mostly in the U.S.A., can considerably increase the efficiency of methane recovery and improve the safety of mines throughout the world.