Spontaneous heating in a sealed area is a matter of safety concern. There will be invariable leakages-either into the sealed area or out of it into the mine atmosphere- and the problem of fresh air leaking into sealed area is considered risky because it carries Oxygen. One way, it is argued, to address this problem is by ensuring that if we ensure that the stoppings/seals do not experience much pressure differential, then, the possibility of transfer of gases one way or the other is reduced (if not prevented). The way to achieve this is through the construction of pressure-balance chambers. These pressure chambers are essentially a process of creating a void space between the mine seals and the active mining side. The pressure in the chamber is adjusted through some mechanism on a continuous basis such that the seal does not experience much pressure differential and thereby does not leak.
In the method of positive pressure chambers, the approach is one of maintaining the chamber created at a positive pressure (related to the sealed area) by the injection of an inert gas such as nitrogen continuously, if necessary, to accommodate leaks either into the sealed area or out into the active mine air. Although a sound technology, the continuous injection of inert gas can make it an expensive proposition.
As a tool, pressure balance appears attractive; however, several unknown and unknowable factors can make the exercise frustrating. Through simulation studies, the paper highlights the challenges in successfully adopting pressure balancing as a tool for spontaneous combustion control in sealed areas.
