Today's industry design trends for escape ways, separation and segregation appear to have been based largely on interpretations of current legislation and opinions of regulators. This approach has been regularly found onerous and costly to implement. It is also of note that the design approach has historically occurred without use of a formal risk management process.As the current act and regulations are risk based, it was considered that a more synergetic legislative compliance solution would be achieved using a fire engineered performance-based approach.This paper reports on a site-based study that addresses underground fires and the effects these fires have on underground personnel, ventilation and infrastructure in the context of fire occurrence within current design parameters.To establish context and purpose, a mine-site risk assessment was initially carried out to identify and prioritise credible threat scenarios in relation to fixed and mobile plants that could affect the underground environment.The deliberations of a risk workshop carried out at Ensham Mine involving key personnel, identified a range of credible fire-related threats. These are summarised as follows: coal fire on belt, spread of fire, multiple locations coal fire at transfer point, drive head, loop take up, winches oil, grease fire electrical fire, transformer, starter, cables services roadway fire - vehicle, electrical transport road vehicle fire ingress of smoke from external sources - surface vehicle, bush fire._x000D_
The experienced risk workshop attendees established that fires associated with belts and transfer points (items 1 and 2) were the most significant credible threats and would be the focus of the study. The hypothetical fire scenario for item 1 - coal fire on belt, spread of fire, multiple locations - as assessed in this paper, was considered to involve the overheating of an exposed conveyor belt roller in a primary escape way.The intent of the study was to compare two contrasting alternative approaches to managing potential belt fires and consequently determine the lowest fire life safety risk outcome for escaping mine workers.The first method was considered to be a typical prescriptive' approach involving the construction of a passive fire barrier to enclose the exposed belt section across the primary escape road and by doing so, enclose a potentially fully developed fire. The alternative approach utilised a very early fire detection solution using video based fire detection (VBFD) to detect early smouldering pyrolysis fires in the absence of a passive fire barrier.Initial computer simulations using computational fluid dynamics (CFD) models were developed. This was done to support limited empirical data, which was required to substantiate the effects of fires associated with conveyor belt systems. In particular, bearing and roller heating events were seen as the primary threat.The modelling required an estimation of a belt fire fuel source, expected size of fire and the produced contamination for the agreed scenario using CFD. The two design fires were quite different to each other, as follows: a fully developed fire involved 500 kg of coal burning at the exposed belt section of a primary escape road a smouldering pyrolysis fire involving a small quantity of coal and grease on a belt roller at the exposed belt section of a primary escape road._x000D_
Based on analysis, numerical modelling and the results of experimentation carried out at Safety In Mining Testing and Research Station (SIMTARS) during 2012, it was estimated that the early detection approach would achieve a lower fire life safety risk for miners, as considerably longer available safe evacuation time (ASET) was achievable.CITATION:Mendham, F and Hart, J, 2013. Fire safety engineering applied to underground coal mining, in Proceedings The Australian Mine Ventilation Conference, pp 283-290 (The Australasian Institute of Mining and Metallurgy: Melbourne).