In bituminous coal mining, a person who supervises the work of robbers in
removing pillars of coal that were left to support the roof of working
places during mining operations. Syn:rib boss
Failure of remnants, promontories, as well as pillars, by crushing.
Spalding
Removal of ore from a series of stopes or rooms, leaving pillars between.
Eventually the pillars are forced or allowed to cave under the weight of
the roof.
Coal secured in pillar robbing. Fay
A wide irregular drift or entry, in firm dry ground, in which the roof is
supported by pillars of natural earth or by artificial pillars of stone,
without using timber. Fay
The recovery or working away of the pillars of coal that were left during
the first operation of working in the pillar-and-stall method. Also called
pillar mining. See also:jenkin; jud; pillar robbing; pillar extraction.
Nelson
The operation of extracting coal pillars, on the retreating system, in a
pillar method of working. Nelson
a. The line along which pillars are being mined.
b. Air currents which have definitely coursed through an inaccessible
abandoned panel or area or which have ventilated a pillar line or a
pillared area, regardless of the methane content or absence of methane in
such air.
A person who builds stone packs in mine workings.
See also:pack builder
Methods of working coal seams, which have been given different names in
different coalfields, such as stoop-and-room in Scotland; bord-and-pillar
in Durham, England; and single and double stalls in South Wales. There are
many modifications of pillar mining, but in general, there are two stages:
(1) the driving of narrow roadways and thus forming a number of coal
pillars, and (2) the extraction of the pillars--often on the retreating
system. Pillar methods of mining are widely used in the United States,
while the longwall method is favored in Great Britain. Pillar methods also
are used for working stratified deposits of ironstone, rock salt, slate,
and other layered minerals. Nelson
Any of several systems, including the room-and-pillar system, the block
system, and the bord-and-pillar system. Woodruff
Mining of pillars during retreat mining to increase the overall recovery
of the reserve.
a. Roadway formed in coal pillars. Nelson
b. Working road or incline in pillars having a range of longwall faces on
either side. Fay
See:robber
a. The systematic removal of the coal pillars or ore between rooms or
chambers to regulate the subsidence of the roof. Also called pillar
drawing. Fay
b. The removal of ore pillars in sublevel stoping or slicing.
See also:sublevel stoping
c. Formerly, in pillar-and-stall mining, the coal pillars left were too
small, and miners were satisfied to gain some coal by robbing the pillars,
usually from middle portions, the remaining coal being too dangerous to
extract. Nelson
pillar robbing and hand filling
See:sublevel stoping
An opening or crosscut driven through a pillar in the course of
extraction.
The formula for pillar strength can be expressed as follows: S = C (L/T)
1/2 where the coefficient, C, is directly dependent upon friction,
L is the least pillar width, and T is the thickness. Coal Age, 3
Working coal in much the same manner as with the pillar-and-stall system.
A rock texture characterized by piles of lobate, pillow-shaped masses;
individual pillows range up to several meters across; typical of basalt
that has erupted under an appreciable depth of water.
A metal-cased rubber block that allows limited motion to a support or
thrust member. Nichols, 1