What is Gas Drainage in underground mining?

• A. A ventilation practice that increases gas production.
• B. A method to water down chemical reagents.
• C. The controlled removal of methane and other gases via boreholes or headings to reduce explosion risk and ensure safe ventilation.
• D. A process to store gas for future use.

Answer: (C)

Gas drainage is the controlled removal of methane and other gases from coal seams and surrounding rock through boreholes or mine openings (headings) to lower gas concentrations in the active workings. The main purpose is to reduce the risk of gas explosions and to improve safe ventilation as mining progresses. By extracting gas ahead of the working faces, the mine lowers the amount of combustible gas that could accumulate, making airflow more effective and the environment safer for personnel and equipment. This often involves drilling drainage boreholes and routing the gas to surface or into the ventilation system, sometimes alongside other gas-control strategies. It is not about increasing gas production for its own sake, nor about simply diluting with water or reagents, and while captured gas can be used in some cases, the primary aim is safer, more controllable gas levels in the mine.