stopping

A stopping is a physical barrier built across a mine passage to direct, obstruct, or redirect the flow of ventilating air. It might be a door, a built-up wall, or a sealed partition constructed from timber, concrete, brick, or canvas depending on the mine's design and the pressure differentials involved. The stopping's core function is to create an intentional bottleneck in the mine's ventilation circuit, forcing fresh air down one route and exhausted air down another, rather than allowing air to take random paths through abandoned or worked-out sections.

Stoppings fall into several categories. A permanent stopping is built to remain in place indefinitely and is typically constructed with solid materials like concrete or brick. A temporary stopping, made from timber frames covered with canvas or plastic sheeting, can be installed and removed as mining activity shifts. An air-tight stopping is sealed tightly to prevent any bypass leakage; a brattice stopping is a canvas or synthetic membrane partition that hangs from the roof and can permit controlled airflow around its edges. Double stoppings, with an airlock chamber between them, are used where air pressure differences are extreme.

In practice, stoppings are erected at junctions, at sealed-off sections, or at the boundary between active working areas and areas being allowed to cool or recover. A colliery managing methane liberation, for example, will use stoppings to isolate gassy headings and channel air away from personnel. Without stoppings, methane might accumulate in dead ends, or fresh air might short-circuit back to the fan intake without reaching all working sections. Stoppings also help regulate pressure so that air moves at optimal velocity, neither stagnating nor rushing dangerously fast.

Practical considerations

The term itself derives from the verb to stop, used in the mining sense from at least the 18th century. A stopping 'stops' the air, though in ventilation engineering the concept is really about redirection rather than complete blockage. Leakage around stoppings is a chronic problem; even small gaps undermine the intended ventilation circuit. Air velocities and pressure readings are monitored before and after major stoppings to confirm they are performing as designed.

Stoppings must be durable enough to resist the mechanical stress of moving air, vibration from nearby machinery, and thermal cycling in some mines. They are inspected regularly during routine ventilation audits. A deteriorated or poorly sealed stopping can render an entire ventilation system ineffective, potentially trapping contaminated air in active workings. Maintenance and replacement of stoppings is a standard ongoing cost in mine operations.