DEVELOPMENTS IN METHANE DRAINAGE TECHNIQUES IN THE SOUTH WALES AREA.

The paper outlines the history of methane drainage from its introduction in 1950 to the present time when thirty-three of the Area collieries are employing such techniques. The development of the South Wales Methane Drainage Grid and the resultant effects from its installation are also discussed. Two major developments in techniques in working collieries are introduced; these are the purity controlled drainage of gas from sealed-off areas and the closed-loop speed control of extractor drive motors. The contributions which these schemes have made towards safer working conditions in the mine, as well as increased financial proceeds from the resultant increases in gas yields and sales, are illustrated. The final section of the paper deals with the provision of a reinforced concrete plug in the upcast shaft at Avon Colliery - the first such installation in Britain. The results obtained to date are presented, together with costs analysis of the scheme. It is suggested that each of the developments outlined could be adopted with great benefits in similar sites or locations in other coalfields.