Where are bleeders typically found in a mining context?

Bleeders in a mining context are typically found around pillared areas. This is because bleeder systems are designed to provide ventilation to ensure that any gases produced during mining operations are safely directed away from areas where workers are present. Pillared areas, where coal or minerals are extracted while leaving supporting pillars in place, often require careful management of airflow to prevent the accumulation of harmful gases like methane. By locating bleeders around these pillared zones, miners can effectively ventilate the work environment and enhance safety.

In contrast, the other locations mentioned do not serve the same functional purpose with regards to safety and ventilation. Locations near the surface may not require the same level of gas management due to natural airflow. Areas without pillars may not generate gas in the same way, and open-pit mines may utilize different ventilation strategies that do not involve bleeders in the same manner as underground operations. Thus, the presence of bleeders is closely linked to the mining practices employed in pillared areas where airflow management is critical.