Fr. See:longwall
a. A long face of coal. Stoces
b. A method of working coal seams believed to have originated in
Shropshire, England, toward the end of the 17th century. The seam is
removed in one operation by means of a long working face or wall, thus the
name. The workings advance (or retreat) in a continuous line, which may be
several hundred yards in length. The space from which the coal has been
removed (the gob, goaf, or waste) either is allowed to collapse (caving)
or is completely or partially filled or stowed with stone and debris. The
stowing material is obtained from any dirt in the seam and from the
ripping operations on the roadways to gain height. Stowing material is
sometimes brought down from the surface and packed by hand or by
mechanical means. See also:longwall advancing; longwall retreating.
Also known as longwork; Shropshire method; combination longwall; and
Nottingham or Barry system. Syn:combination longwall
Nelson; Fay
c. Opposite of shortwall. See also:longwall mining
A system of longwall working in which the faces advance from the shafts
toward the boundary or other limit lines. In this method, all the roadways
are in worked-out areas. See also:longwall
Compact machine, driven by compressed air or electricity, that cuts into
the coal face with its jib at right angles to its body.
See also:longwall machine
A power-driven machine used for shearing coal on relatively long faces.
See also:longwall coal cutter
In bituminous coal mining, one who extracts coal from seams by a
specialized method known as longwall mining. In this method, all coal is
extracted as the work progresses, and the roof caves behind the working
face.
a. A full-extraction method for mining large panels of coal.
b. A system of mining in which all the minable coal is recovered in one
operation. Hudson
c. A method of mining flat-bedded deposits, in which the working face is
advanced over a considerable width at one time. See also:longwall
Pryor, 3
A method of underland stoping in which rapid advance of the face is
maintained, and by working the faces at an angle of 60 degrees to the
strike, the peak travels down the dip at twice the rate of the face
advance. This method was introduced on the Witwatersrand for stoping below
5,000 ft (1,524 m), where rapid face advance resulting from the closer
spacing of holes reduces the incidence of rock bursts. Higham
The extraction of the coal pillars formed by a pillar method of working,
by a longwall face, which can be advancing or retreating. Where the crush
is not excessive, this method is more efficient and often safer than
extracting each pillar individually. Nelson
A system of longwall working in which the developing headings are driven
narrow to the boundary or limit line and then the coal seam is extracted
by longwall faces retreating toward the shaft. In this method, all the
roadways are in the solid coal seam and the waste areas are left behind.
See also:longwall; mechanized heading development. Nelson
Eng. The best Yorkshire sandstone, Rossendale District. CF:lunker
Arkell
Burma. Ruby mines in which fissures, caves, and hollows in the limestone,
filled with detritus from its disintegration, are followed, and their
contents, often cemented or buried under recent travertine, are extracted
and washed. Hess
Lustrous hematite, Fe2 O3 . Specular iron ore; iron glance.
Mohs hardness, 6; sp gr, 5.2. Pryor, 3
A vessel to receive ore washings. Standard, 2
Eng. A variant of loam, esp. in the Thames Valley; applied to Thanet sand
and dredged mud used for cement. Arkell
A term used when two positive wires are installed in divergent directions
but later come close enough together to be connected. They then form a
series or so-called loop circuit. CF:parallel blasting circuit
Kentucky
An eye at the end of a rod through which tow is passed for cleaning
boreholes.
In ore dressing, smelting, and refining, a laborer who attaches loops
(folded copper sheets or strips) to starting sheets so that sheets can be
suspended in electrolytic tanks. Also called looper puncher. DOT
A system used when a continuous supply of cars must be supplied to a
loading station. In this system, the empty cars are simply coupled to one
end of the standing cars, which are pulled forward by a hoist with the
rope attached to a clip fixed to the side of the cars. The rope is pulled
back by hand for a distance of three or four car-lengths, and the process
is repeated frequently as the end of the rope approaches the hoist.
Wheeler, H.R.
The running together of ore matter into a mass when the ore is only heated
for calcination. CF:loup
Consists of one or more trains of alternating two-high stands. As the
piece being rolled emerges from one stand, it is turned through 180
degrees and entered into the next stand and similarly into the succeeding
stands. In some mills, the looping is performed by hand, while in others
it is done mechanically by means of repeaters or looping channels.
Osborne