One of the cutting points attached to a cutter chain for making a groove
in a coal seam. The picks are made from quality carbon steel or a hard
alloy steel and tipped with fused tungsten carbide, sintered tungsten
carbide, or other hard-wearing material. The advent of the coal-cutter
pick tipped with tungsten carbide on a heat-treated, alloy-steel shank has
resulted in marked improvements in drilling and a reduction in cutting
delays. See also:chain coal cutter; double-ended pick; duckbill pick;
tungsten carbide bit. Nelson
The miners in charge of a coal cutter. A cutting team varies from two to
five with two to three about average. The leading worker is normally
stationed in front of the machine and is in charge of the controls, and an
assistant follows behind. See also:machineman
Nelson
A machine powered by compressed air or electricity that drives a cutting
chain or other device so as to undercut or overcut a seam, or to remove a
layer of shale. Percussive cutters are used to bore holes or to make
vertical cuts (nicking, shearing); disk, bar, and chain cutters carry
small picks that undercut the seam as the machine travels.
Pryor, 3
See:machineman
A place where coal is dug. Craigie
Usually an electric rotary drill of a light, compact design. Aluminum and
its alloys usually are used to reduce weight. Where dust is a hazard, wet
drilling is employed. With a 1-hp (745.7-W) electric drill, speeds up to 6
ft/min (1.83 m/min) are possible. Light percussive drills, operated by
compressed air, and hand-operated drills are also employed.
See also:electric coal drill
In coal mining, a worker who uses a hand or power drill to drill holes
into the working face of the coal into which explosives are charged and
set off to blast down the coal. DOT
A plant or vessel in which water or moisture is removed from fine coal.
Artificial drying of fine coal is not often employed. Fine coal is removed
from wash water by dewatering classifiers or by vacuum filtration.
See also:dryer; thermal drying. Nelson
a. The general name for coal particles of small size. In experimental mine
testing, particles that will not pass through a 20-mesh screen--
1/32-in-square (0.8-mm-square) openings--are not considered as coal dust.
Rice, 2
b. In 1964, a series of laboratory tests were made with a spark source on
aluminum powder and cornstarch (both dusts presenting a more severe
explosion hazard than coal dust). It was found that particles passing a
U.S. Standard No. 40 sieve (particles less than 0.016 in or 0.4 mm)
contributed to an explosion in the laboratory bomb. The 0.016-in particle
diameter was recommended as the definition for dust in surface industry.
Thus, two definitions of dust exist. For coal mines, dust consists of
particles passing a U.S. Standard No. 20 sieve (particles less than 850 mu
m), and for surface industries, dust consists of particles passing a No.
40 sieve (particles less than 425 mu m). The use of two definitions is not
incongruous since the potential igniting sources in a coal mine can be
much more severe than those in surface industries. MSHA, 1
c. The dust produced by the breakage and crushing of coal underground and
at coal preparation plants. It is usually intermixed with a varying
proportion of stone dust. Coal dust in mines presents two main dangers:
explosion hazard and pneumoconiosis hazard. The explosibility of a coal
dust cloud depends upon its fineness, purity, and volatile content. The
dust particles believed to be harmful from the pneumoconiosis aspect are
those of 5 mu m and under. In mines, the most common explosive dust
encountered is bituminous coal dust. The U.S. Bureau of Mines has
established that coal dust in the absence of gas can explode and that
explosions can occur in any shape of mine opening.
See also:dust-free conditions
A mine explosion caused by the ignition of fine coal dust. It is
considered that an explosion involving coal dust alone is relatively rare.
It demands the simultaneous formation of a flammable dust cloud and the
means of ignition within it. The flame and force of a combustible gases
explosion are the common basic causes of a coal-dust explosion. The
advancing wave of the explosion stirs up the dust on the roadways and thus
feeds the flame with the fuel for propagation.
See also:colliery explosion; gas explosion; stone-dust barrier.
Nelson
Percentage of fines and dust passing the 0.0117-in (0.30-mm) mesh or
48-mesh. Bennett
A building in which coal is raised and stored preparatory to loading on
cars, ships, etc. Mathews
Massive copper made from ground, brittle, cathode copper by briquetting
and sintering in a reducing atmosphere at high temperatures with pressure.
ASM, 1
See:briquette
a. The mining face from which coal is extracted by longwall, room, or
narrow-stall system. See also:face
b. A working place in a colliery where coal is hewn, won, got, or gotten
from the exposed face of a seam by face workers. Pryor, 3
a. An area of country, the underlying rocks of which contain workable coal
seams. The distribution of coalfields was largely determined by folding
movements and subsequent denudation. The original coal areas were clearly
larger than the present coalfields. See also:coal basin; field.
Nelson
b. A region in which coal deposits of known or possible economic value
occur. AGI
See:flotation; froth flotation.
a. A stratigraphic coal-bearing unit in coal measures.
b. A stratum in which coal predominates. Craigie
The content of fixed carbon divided by the content of volatile matter is
called the fuel ratio. According to their fuel ratios, coals have been
classified as anthracite, at least 10; semianthracite, 6 to 10;
semibituminous, 3 to 6; and bituminous, 3 or less.
In coal mining, one who operates a hoist for raising coal to the surface
where separate shafts or compartments are used for handling coal and
people. DOT
Those processes involved in the genetic and metamorphic history of
coalbeds. The plant materials that form coal may be present in vitrinized
or fusinized form. Materials contributing to coal differ in their response
to diagenetic and metamorphic agencies, and the three essential processes
of coalification are called incorporation, vitrinization, and
fusinization. See also:incorporation; carbonification.
Syn:incarbonization