Gas Control in Underground Coal Mining
AUTHORS: D.P. Creedy, A. Saghafi, R. Lama
DATE: April 1997
Methane-rich gases occur naturally in coal seams and are released whenever these are disturbed by mining. Emissions of carbon dioxide are also encountered in some countries. The risks associated with these gases in underground coal mines are minimised by diluting them to safe concentrations with ventilation air, diverting gas away from working areas and, if necessary, capturing gas in boreholes before it can enter mine airways.
Increasing gas flows are an inevitable consequence of increasing rates of coal production, especially on longwall faces where seams above and below the worked seam can contribute substantial quantities of gas. Most countries with high-production, mechanised longwall operations at depth would be unable to achieve their coal production targets without gas capture systems.
This report reviews ventilation and gas drainage practices that have been developed in various countries to facilitate the working not only of gassy seams but also those that are prone to instantaneous outbursts of gas and coal or rock. There is considerable scope for improving gas control in underground coal mines, particularly in the non-OECD countries where the frequency and severity of gas-related incidents are unacceptably high.
The importance of health and safety management systems, safety management systems, safety legislation and enforcement, human attitudes, training, planning and equipment maintenance to the successful implementation of existing or new technology is stressed. Opportunities for transferring gas control technology are identified, as are research needs to fill remaining knowledge gaps. Greater use could be made of the methane captured in coal mine gas drainage systems. Although the environmental benefits of mine gas utilisation schemes are well recognised, the cost benefits have not always materialised.