fanhouse

A fanhouse is a surface structure that contains the primary ventilation fan for an underground mine. It sits at the exhaust point of the mine's ventilation circuit, pulling stale air from the workings and expelling it to atmosphere. The building itself must be robust enough to house a fan running continuously at high volume, often 100,000 cubic feet per minute or more, with enough structural integrity to handle vibration and the pressure differentials created by the fan's operation.

The fanhouse's location is critical to mine safety. It must sit where it can draw air from the main return airway without creating leakage paths that bypass the fan. A poorly sited fanhouse allows air to short-circuit back into the mine without passing through working areas, leaving pockets of methane or poor air quality in active sections. The building must also be positioned where wind patterns or proximity to intake shafts won't allow contaminated surface air to recirculate into the mine.

Fanhouses typically house either centrifugal or axial fans, depending on the required pressure and volume. Coal mines with deeper workings often need centrifugal fans to overcome higher resistance; shallower operations may use axial fans. The fan size reflects the mine's geometry and the total air resistance of all connected airways. A fan undersized for its circuit will fail to clear hazardous gases; an oversized fan wastes energy and can create excessive pressure that damages seals and causes air leakage through boreholes.

The structure itself must isolate vibration from the surrounding landscape, typically using isolation mounts and concrete pads. Damping prevents the fan's rotational forces from cracking the building or nearby infrastructure. Access doors and emergency venting provisions allow workers to service the fan unit safely and prevent pressure buildup if the fan fails unexpectedly.

Fanhouse design varies by mining method and jurisdiction. Metal mines typically have separate intake and exhaust fanhouses; coal operations often use a single large fanhouse with the fan positioned to draw from the mine return. In either case, the fanhouse is part of the mine's largest single capital investment in safety infrastructure: the ventilation system itself cannot function without it.