Hi Mike
This is normal coal mining practice even today in "Bord and Pillar" work.
(where the supporting pillers are of larger dimensions than the roadways
..as opposed to "Room and Pillar" where the opposite applies)
The "solid"coal is a panel or district is first formed into pillars by a
series of roadways ... referred to as "first workings"
When the process has reached to boundary of the area, the pillars are
extracted by spitting (driving a roadway through them) and resplitting
until only a "stook" remains. This will generally collapse of its own accord
and eventually the roof will come in.
At times pillars are removed by "siding over" where a strip is taken off
alternate sides.
"Creep" takes place when the ratio of supporting pillars to extracted
roadways is too small and the roof collapse over rides the standing pillar
area. Often associated with the floor in the roadways rising up as the
pillars are pressed into the ground
"Robbing" pillars refers to partial extraction ("perhaps by "splitting")
pillars which were left (or planned to be left) for a specific purpose (ie
to protect a barrier or to support some surface feature).
Trust the above helps.. As you see it is a very complicated business ...
very specific to individual mines and difficult to explain in a few words .
Regards
John
----- Original Message -----
From: "Mike Syer" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, September 12, 2008 6:59 AM
Subject: Working the pillars
Please can some one advise about the practice of working pillars left
in coal that had first been mined some time earlier?
The following is an extract from an 1848 report by the Bishop of
Durham’s agent, who was assessing the value of remaining coals in the
Quarrington royalty, in order to place a value on it prior to the
renewal of its lease. It refers to one of the coal mines in that
royalty. The original workings had been in the 18th century.
“What is left is small pillars not workable to profit if workable at
all. The Seam being near the surface, the Pillars left are of
extremely small dimensions.”
That suggests to me that there had not just been two processes, namely
(1) hewing out the roads & bords and then (2) removing the pillars,
but also an intermediate one (or the final one, if some coal was left
permanently unworked), namely (3) the PARTIAL removal of the pillars.
I have read elsewhere of this practice being called “robbing the
pillars” and that it led to creep - making the rest of the coal either
less workable or, perhaps, just less worth working, in the days when
small coals were not valued.
Thanks
Mike
-----------------------------------------------------------
I search the web and raise money for the Bowburn Banner Group with
Everyclick.
Join me: http://www.everyclick.com/msyer
-----------------------------------------------------------
|