A term used in England for any summit or top of a mountain or hill, esp.
one that is peaked or pointed. Also, a mountain or hill having a peaked
summit. AGI
A method for the direct production of steel by passing reducing gases over
iron oxide ore, carburizing the reduced ore, and alloying it in an
electric furnace. Thus, a reducing gas, heated to 900 degrees C is passed
over iron oxide ore to produce metallic iron and spent gas. The
carburized, partially reduced metal is melted, reduced, and alloyed in the
electric furnace. Osborne
See:cobbing
An aluminous variety of chrysocolla. Standard, 2
a. A timber, steel, or reinforced concrete plate or post that is driven
into the ground to carry a vertical load (bearing pile) or a horizontal
load from earth or water pressure (sheet pile). Nelson
b. A spiked or sharped-edged plank, beam, or even pipe or girder that is
forced forward or downward (sinking) into running ground with a view to
support. Mason
c. A stack of ore or stones. Gordon
d. A prop of timber. Gordon
e. Long thick laths, etc., answering in shafts in loose or quick ground,
the same purpose as spills in levels, piles being driven vertically.
A dam made by driving piles and filling the interstices with stones. The
surfaces are usually protected with planking.
See:pile extractor
a. A machine for driving down piles; usually consisting of a high frame
with appliances for raising and dropping a pile hammer or for supporting
and guiding a steam or air hammer. Also called pile engine.
Webster 3rd
b. An operator of a pile driver. Webster 3rd
A sheet piling extractor that works on the same principle as the
piledriving hammer, except that the force of the blow is upward rather
than down. Carson, 1
A number of piles driven or cast in situ, will sustain a much heavier load
than a single pile can carry, esp. when connected by a pile cap.
Hammond
This may be a drophammer, a steam hammer, or a diesel hammer of which the
last two are completely automatic. Steam hammers are also able to operate
on compressed air. See also:jetting
The top of a precast concrete pile, protected during driving by packing
under a pile helmet and sometimes by a timber dolly. The top of a timber
pile is protected by a driving band. Hammond
A cast-steel cap covering and protecting the head of a concrete pile
during driving. See also:drophammer
A method of sinking a circular or rectangular shaft through 20 to 30 ft
(6.1 to 9.1 m) of sand or mud at the surface. It cannot be used for
greater depths as each ring of piles reduces the inside dimensions of the
shaft. See also:pile; piling. Nelson
A structure or group of piles. See also:cofferdam
A loosely rolled cylinder of burlap and 1/4-in-mesh (0.6-cm-mesh) hardware
cloth pushed down into a borehole ahead of a string of drill rods to the
point where a large crevice or small cavity has been encountered. At this
point the cylinder tends to unroll partially, forming a mat that acts as a
barrier against which other hole-plugging agents may collect and help seal
off the opening. Long
a. A column of coal or ore left to support the overlying strata or hanging
wall in a mine, generally resulting in a "room and pillar" array. Pillars
are normally left permanently to support the surface or to keep old
workings water tight. Coal pillars, such as those in pillar-and-stall
mining, are extracted at a later period. Syn:stump
See also:barrier pillar; shaft pillar.
b. A block of ore entirely surrounded by stoping, left intentionally for
purposes for ground control or on account of low value. Spalding
c. A column of rock remaining after solution of the surrounding rock.
See also:hoodoo
A system of coal mining in which the working places are rectangular rooms
usually five or ten times as long as they are broad, opened on the upper
side of the gangway. The breasts usually from 5 to 12 yd (4.6 to 11.0 m)
wide, vary with the character of the roof. The rooms or breasts are
separated by pillars of solid coal (broken by small cross headings driven
for ventilation) from 5 to 10 yd (4.6 to 9.1 m) or 12 yd (11 m) wide. The
pillar is really a solid wall of coal separating the working places. When
the object is to obtain all the coal that can be recovered as quickly as
possible, the pillars are left thin; but where this plan is likely to
induce a crush or squeeze that may seriously injure the mine, larger
pillars are left and after the mine has been worked out, the pillars are
"robbed" by mining from them until the roof comes down and prevents
further working. In the steeply inclined seams of the anthracite regions
the pillar-and-breast system is employed by working the bed in "lifts".
Also called pillar-and-stall; post-and-stall; bord-and-pillar.
Syn:board-and-pillar; board-and-wall. Fay
A pillar method of working often adopted in extracting a proportion of
thick deposits of salt or gypsum. The method may be adopted where the
value of the mineral in the pillars is less than the cost of setting
artificial supports. Nelson
A system of mining whereby solid blocks of coal are left on either side of
miner's working places to support the roof until first-mining has been
completed, when the pillar coal is then recovered.
See also:room-and-pillar
a. A system of working coal and other minerals where the first stage of
excavation is accomplished with the roof sustained by coal or ore.
See also:pillar-and-breast; post-and-stall.
b. One of the earliest methods of working coal seams in Great Britain. It
is employed in thick seams and where valuable surface buildings require
protection from damage by subsidence. A number of narrow roadways are
driven in the coal seam to a predetermined boundary. There are two sets of
roadways, driven at right angles to each other, and thus the seam is
divided into a large number of square or rectangular pillars. These
pillars are extracted at a later period. The driving of the narrow
roadways is termed working the whole while pillar working is known as
working the broken. The width of the roadways and their distance apart are
governed by the thickness and nature of the coal seam and the type of roof
and floor. The main headings are driven forward and connected at intervals
by crosscuts or stentons for ventilation and as a second exit. The bords
are driven off the main headings at fixed distances apart, and are
connected at intervals by walls. The width of the main headings,
crosscuts, and bords varies from 3 to 5 yd (2.7 to 4.6 m). The bords are
driven from 15 to 60 yd (13.7 to 54.9 m) apart. The walls are about 2 to 3
yd (1.8 to 2.7 m) wide and driven at similar or greater intervals
according to the size of pillars to be formed. Modern pillar-and-stall
mining is highly mechanized. See also:crosscut;
mechanized heading development; stenton. Also called bord-and-pillar.
Nelson