Certainly highlighted to me the wisdom of having pre-prepared emergency stopping sites at key points.The absence of such sites in a seam already known to be susceptible [even one heating in that unit], combined with a mining method that leaves behind significant quantities of top coal in goaf areas is astonishing to me. In the UK at this time, these sites were prepared as part of the initial development of an area to be mined and stockpiles of blocks and materials sufficient to complete the stopping walls were maintained at or very near the sites. These sites had as much blockwork ready built, as was practical for the mining operations, and that blockwork was well keyed in to the surrounding strata. Built into the temporary blockwork, would be be a 2 - 3 foot diameter steel tube that would allow some ventilation to pass in a controlled manner, these being the last thing to be sealed off after stoppings were built. Getting materials hauled to site can be a slow process at the best of times, a problem made much worse when there is a active fire. Introducing a further delay to salvage machinery is, to me, unforgiveable. Was that machine worth all those lives, and the loss of the mine ?? The fact that an initial methane ignition developed into a coal dust explosion, also suggests that scant attention was being paid to dust suppression at the faces and stonedusting and barriers or other suppression methods, though the very fact that so much broken coal was present in the inaccessible goaf areas, would make it somewhat more difficult to accomplish. In all, this was a tragic disaster that could so easily have been prevented.
Strange they would hold a coal top, why not cut to the stone top then take the floor coal whilst retreating/pillaring? This is what we do when the seam is very thick, in the South Wales colliery I work at; Aberpergwm.
Jordan this generally comes down to a culmination of factors - There is no specific answer at Kianga but suspect that the description of the choice of extraction method at Kianga would have been similar to the decision at Moura 4. As you can see at Moura 4 they tried a lot of different methods but in the end it comes down to • Seam Thickness • Coal Quality and • % extraction If they had considered the Spon Com risk, they certainly would not have chosen to leave broken coal in the goaf. Probably better quality in the bottom on the seam. The other thing is the extraction ratio. If you are taking bottoms the extraction % isn’t as high as if you are taking pillars. So the only thing I can think of why anyone would do that is to: • Get better quality coal, • Get a higher % of extraction with pillar extraction rather than taking bottoms.
Thanks for your response, normally in the multi entry system you extract the floor coal and cut or 'fir tree' the pillars on the retreat. That is after a district is established to the fullest extent of a particular panel. We have even split pillars, creating a bolted road through the centre to enable greater % extraction. Perhaps it was as you say, they didn't have a market for the poorer quality top coal. Not a problem in the anthracite seam at Aberpergwm
Certainly highlighted to me the wisdom of having pre-prepared emergency stopping sites at key points.The absence of such sites in a seam already known to be susceptible [even one heating in that unit], combined with a mining method that leaves behind significant quantities of top coal in goaf areas is astonishing to me. In the UK at this time, these sites were prepared as part of the initial development of an area to be mined and stockpiles of blocks and materials sufficient to complete the stopping walls were maintained at or very near the sites. These sites had as much blockwork ready built, as was practical for the mining operations, and that blockwork was well keyed in to the surrounding strata. Built into the temporary blockwork, would be be a 2 - 3 foot diameter steel tube that would allow some ventilation to pass in a controlled manner, these being the last thing to be sealed off after stoppings were built. Getting materials hauled to site can be a slow process at the best of times, a problem made much worse when there is a active fire. Introducing a further delay to salvage machinery is, to me, unforgiveable. Was that machine worth all those lives, and the loss of the mine ??
The fact that an initial methane ignition developed into a coal dust explosion, also suggests that scant attention was being paid to dust suppression at the faces and stonedusting and barriers or other suppression methods, though the very fact that so much broken coal was present in the inaccessible goaf areas, would make it somewhat more difficult to accomplish.
In all, this was a tragic disaster that could so easily have been prevented.
Strange they would hold a coal top, why not cut to the stone top then take the floor coal whilst retreating/pillaring? This is what we do when the seam is very thick, in the South Wales colliery I work at; Aberpergwm.
Jordan this generally comes down to a culmination of factors - There is no specific answer at Kianga but suspect that the description of the choice of extraction method at Kianga would have been similar to the decision at Moura 4. As you can see at Moura 4 they tried a lot of different methods but in the end it comes down to
• Seam Thickness
• Coal Quality and
• % extraction
If they had considered the Spon Com risk, they certainly would not have chosen to leave broken coal in the goaf.
Probably better quality in the bottom on the seam. The other thing is the extraction ratio. If you are taking bottoms the extraction % isn’t as high as if you are taking pillars. So the only thing I can think of why anyone would do that is to:
• Get better quality coal,
• Get a higher % of extraction with pillar extraction rather than taking bottoms.
Thanks for your response, normally in the multi entry system you extract the floor coal and cut or 'fir tree' the pillars on the retreat. That is after a district is established to the fullest extent of a particular panel. We have even split pillars, creating a bolted road through the centre to enable greater % extraction.
Perhaps it was as you say, they didn't have a market for the poorer quality top coal. Not a problem in the anthracite seam at Aberpergwm
Tragic lose of life. A daily risk for all coal miners.
But not for the millionaires profiting from them
@@nadapenny8592 exaclty..miners are well paid but the profit to the owner is far and away much much greater than any miner ..