On Sat, 12 Aug 2000 09:18:49 -0700 David Summers
<[log in to unmask]> wrote:
> Having once tried to extinguish a burning coal seam the problems are
> complex. Even small areas (about the size of a dime) that are left
> very hot can reignite if air is present and the flame front is
> nowhere near vertical, various layers burning at different rates and
> making it hard to identify the actual position of what is actually
> alight.
>
> Dave
>
Hi
I could not agree more. However it is possible to
extinguish such underground fires remotely if the
circumstances are right.
The problem
I recollect that in the 1980s we had an underground fire on
a longwall face in the Beeston seam at Fryston Colliery
(West Yorkshire)at a depth of about 700m. The coalface was
several miles from the shafts. The fire was caused by
spontaneous combustion in the "gob" or waste. If the fire
had spread it would have jeopardised the surrounding
district and the future development of the mine. The seam
gradually dipped outbye from the coalface but then rose
again forming a small syncline.
The solution
A deep borehole was drilled from the surface to a point
just into the waste behind the coalface. The borehole was
cased before boring the final distance into the waste. A
calculated amount of water was pumped down the borehole.
The water was initially extracted from a shallow aquifer
via a second borehole(the holding lagoons constructed on
the surface were enormous). In the workings the water
flowed down dip through the waste and accumulated in both
the maingate and tailgate access roads to the
face to form natural stoppings (barriers)in solid
coal. Having sealed off the face, nitrogen was then pumped
down the borehole and the fire was eventually snuffed out
and access to the district regained.
An expensive way of putting out underground fires but very
cost effective in comparison to the X million pounds of
investment that was at stake! Desperate circumstances often
promote extreme measures - this one worked.
Rob Vernon
----------------------
Rob Vernon
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