Paul Medcraft, MineARC Australasian Bus Development Manager says “the refuge chamber industry is in many respects still in its infancy having begun in earnest only 13 years ago. MineARC was there at the beginning having recognised the opportunity to offer a real chance at survival in an emergency with the introduction of vital air conditioning systems and scrubbers to remove deadly CO2 and CO gas. In those early days the regulations in West Australian mining made no reference of any significance to providing refuge other than fresh air bays. In many respects it was the ‘in the field tests’ by MineARC that helped the then Department of Mines in Western Australia to produce its first paper on the use of refuge chambers in metalliferous mines, back in 2005. In the years since, regulations around Australia have incorporated refuge chambers as a key component of mine planning.“Overseas the situation is very similar with countries adopting some of the Australian ideals into their own regulations, especially the US and Chinese coal industries; both countries having stretched the boundaries of what is possible. China for example, demands chambers are capable of surviving a 45 psi overpressure blast and flash fires up to 1,200oC. As an aside, it’s not enough just to have a chamber that is capable of achieving this, you also need a detailed plan around placement of the chambers to ensure the people entrapped within survive [not much point proclaiming the robustness of a 6 t chamber that gets picked up by the shockwave of a methane explosion, ending further out-bye than it started and buried in debris. The occupants within would have stood no chance of survival.
“The message is simple; it is not enough just to buy a chamber, a deal of thought must go in to how chambers are positioned to ensure they provide a genuine survival opportunity. Issues such as ensuring placement out of the direct path of potential shockwaves are critical. There has been significant research conducted in the US on methane explosions, within a disused coal mine, to establish just how quickly a shockwave will dissipate and the subsequent best points to locate refuge chambers. Documents such as ‘Explosions and Refuge Chambers: Effects of blast pressure on structures and the human body, by R. Karl Zipf, Jr., Ph.D., P.E. and Kenneth L. Cashdollar, give considerable insight into the surrounding issues.
“Refuge chamber manufacturers continue to develop better solutions and different ways to approach old problems. For the most part the changes have been evolutionary rather than revolutionary. And for the most part that has suited the coal industries. It is interesting to note that while we as manufacturers have produced those incremental changes, we haven’t been challenged or pushed by the Australian coal industry to find out the extent of what is possible; to find a ‘game changer’ so to speak, that could significantly improve survival opportunities for miners.
“In recent months, one game changing initiative arrived on our desk via Queensland, but not from Queensland coal, rather, a tunnelling project in suburban Brisbane. MineARC had won the tender to produce four custom built refuge chambers for the construction phase of said project.
“However, in the final stages of consultation with MineARC engineers there was a twist. As a result of an independent assessment by the QLD Fire Brigade, MineARC was asked if it was possible to produce a chamber capable of protecting the occupants from a fire over an extended duration, i.e. not just a flash fire, but a fire lasting a period of time.
“Our research indicated that to date few refuge chamber manufacturers had made any significant attempt to meet this specification, so, MineARC engineers set about investigating possible design solutions. It is important to note that the primary purpose of the chamber, to keep its occupants safe for 36 hours, was still required. However, with the Fire Brigade’s additional specification, the chamber would now also need to maintain a safe internal environment when faced with prolonged temperatures of up to 300°C. It became immediately apparent that there were many issues to overcome.
“Firstly, refuge chambers operate using external battery banks, external air conditioning condensers, external sirens, lights and so on – all of which would not survive temperatures of 300oC. Secondly, as an excellent heat conductor, all steel on steel contact throughout the chamber will result in transient heat from the outside reaching the inside. The list of problems went on and on.
“After numerous rounds of material fabrication analysis and simulations, a combination of internal and external cladding achieved the desired results. Along the way we learned a lot; one thing we discovered was that fireproof material did not necessarily mean fireproof. For example one product rated at 200oC, if exposed to temperatures in excess of 300oC, would suddenly become an accelerant!
“Our solution involved two independent air-conditioning and scrubbing systems, one for normal entrapment and the other in the presence of extreme heat. If an extreme heat scenario eventuates, the chamber would close insulation panels to protect critical equipment such as batteries and condensers to ensure they remained functional later on.
“The end result: The client is satisfied, the QLD Fire Brigade is equally satisfied, and we now have a new approach to prolonged fire risk that easily transfers over into mining and other industries.
“The game changer starts simply by asking the question; how safe can we make it? It forces us to re-examine how we approach risks inside mines, in particular coal mines.
“As a result MineARC now has coal mine refuge chambers that can withstand a 45 to 90 psi blast and flash fires up to 1,200oC; chambers that can endure ongoing heat and fire up to 300oC for hours and can provide the critical requirements to sustain life in high explosion risk zones for in excess of 96 hours.
“Yet so far we haven’t found anyone in the Australian coal industry who thinks this level of safety might be of any value. In fact the vast majority of the Australian coal industry continues to hold the belief that refuge chambers have no role to play in emergency response planning.
“The most recent quote request we received from an Australian coal mine was a case in point. We provided a solution based on our experience manufacturing coal refuge chambers in the US and China. Unfortunately the tender document was a confusing mix of drastically watered down requirements. So much so that in the end we began to look back on our own core beliefs, what we would and would not put the MineARC name to.
“In the end we felt that any resulting chamber based on the tender specifications supplied was unlikely to meet our own standards. It resulted in us withdrawing our offer to quote; the first time we have done so in our history.
“Our question is simple; we have hundreds of refuge chambers in coal mines in the US and China providing resistance to fire, explosions, smoke and other forms of toxic gas. What is the game changer for Australian coal?”
