Explosive coal reduction system tested

Coal mining tragedies often dominate the news, with scences such as PIke River's huge ongoing explosions, the blasts regularly seen across Chinese coal mines, and events such as Nymbodia grabbing everyone's attention.

The cause of these awful events are often linked directly to leaking, and subsequent ignition of methane gas inside the mines.

But what many non-coal miners don't realise is that the real killer explosions, which tragically can sometimes cause major death and destruction in underground coal mines, are only triggered by an ignition of methane gas.  

The main lethal element is a subsequent coal dust explosion set off by the methane ignition which itself can be relatively small and of short duration. 

Traditionally the preventative measure employed by many coal mines is to use stone dust barriers where the stone dust mixes with coal dust and mitigates, or prevents altogether, a subsequent  coal dust explosion but this has proved not always to be 100% effective in guarding against these  events.

Consequently much research has been undertaken over the years to come up with a system which is more efficient in suppressing such dust explosions and much of this revolves around instantaneous automatic water spraying to suppress a spread of such an explosion. 

Much research has been undertaken in the civil tunnelling sector on similar anti-explosion systems, although this has obviously not been in respect of coal dust events which can spread  right throughout a mine's underground workings with the potential to cause widespread loss of life – not only from the effects of an explosion itself but from toxic gases and lack of oxygen which result.

BMT WBM, an Australian subsidiary of UK headquartered BMT Group , and SkillPro Services, also from Australia, have just announced that they have successfully suppressed a coal dust explosion using  their Active Barrier prototype system in the CSIR's experimental tunnel in Kloppersbos, South Africa. 

The companies say that his system could play an integral role in enhancing the future safety of coal miners.

Historically, coal dust explosions have been the number one cause of fatalities within underground coal mines and even today, despite the use of various passive countermeasures, these explosions cause many deaths worldwide. 

David Proud, Business Development Manager for BMT WBM's Machinery group comments: "Using a sensor to detect the approaching coal dust deflagration, the Active Barrier system successfully injected 120 litres of water within 250 milliseconds in order to suppress the explosion, as was predicted by BMT WBM's computational fluid dynamics (CFD) modelling.  This is a ground breaking development – one which could help to mitigate the risks of coal dust explosions occurring in underground coal mines."

BMT WBM and SkillPro have been involved in this R&D project for several years with the financial support of the Australian coal industry research body, ACARP. 

BMT WBM has been modelling the physics and chemistry involved in the entrainment, devolatilisation and combustion of the coal dust particles and the injection and vaporisation of the suppressant. CFD was also used to simulate a range of designs for the prototype suppression device, in order to arrive at a practical and reliable experimental unit.   SkillPro designed the final test apparatus and managed the test programme. 

The ACARP Underground R&D committee has recently awarded the SkillPro/BMT WBM team an excellence award for the research and development undertaken on the Active Barrier project. 

David Humphreys, SkillPro's Manager of the Active Barrier project comments: "A zero harm approach remains top priority for mining companies and SkillPro and BMT WBM are committed to helping their customers achieve this through the development of a range of innovative systems such as the Active Barrier. 

The success of this test programme is another huge leap forward and we hope that we can continue our R&D work to further develop this pioneering product."


This article appeared courtesy of Mineweb. To read more daily international mining news click here.

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