For what purpose are bleeders primarily used?

Bleeders are primarily employed for the ventilation of gob areas in underground mining operations. The gob refers to the area left behind after the extraction of coal, which can create voids filled with potentially harmful gases. Bleeders are specialized openings or passages that allow fresh air to flow into these areas and help remove stale or hazardous air, thus facilitating a healthier environment for workers and mitigating the risk of gas-related hazards.

By ensuring proper ventilation in gob areas, bleeders play a crucial role in maintaining air quality and enhancing safety in the mine. This ventilation process is vital as it helps to control the concentration of gases, thus preventing the build-up of explosive atmospheres and ensuring compliance with health and safety standards.