Abutment - In coal
mining, (1) the
weight of the rocks above a narrow roadway is transferred to the solid
coal along the sides, which act as abutments of the arch of strata
spanning the roadway; and (2) the weight of the rocks over a longwall
face is transferred to the front abutment, that is, the solid coal
ahead of the face and the back abutment, that is, the settled packs
behind the face.
Acid deposition or
acid rain –
Refers loosely to a mixture of wet and dry "deposition" (deposited
material) from the atmosphere containing higher than "normal" amount of
nitric and sulfuric acids. The precursors or chemical forerunners of
acid rain formation result from both natural sources, such as volcanoes
and decaying vegetation, and man-made sources, primarily emissions of
sulfur and nitrogen oxides resulting from fossil fuel combustion.
Acid mine water -
Mine water that contains free sulfuric acid, mainly due to the
weathering of iron pyrites.
Active workings - Any
place in a mine
where miners are normally required to work or travel and which are
ventilated and inspected regularly.
Adit - A nearly
horizontal passage from
the surface by which a mine is entered and dewatered. A blind
horizontal opening into a mountain, with only one entrance.
Advance - Mining in
the same direction, or order of sequence; first mining as distinguished
Agglomeration - A
family of processes
which can be used to concentrate valuable minerals (including coal)
based on their adhesive properties.
Air split - The
division of a current of air into two or more parts.
Airway - Any passage
through which air is carried. Also known as an air course.
Instrument for measuring air velocity.
Angle of dip - The
angle at which strata or mineral deposits are inclined to the
Angle of draw - In
subsidence, this angle is assumed to bisect the angle between the
vertical and the angle of repose of the material and is 20° for
flat seams. For dipping seams, the angle of break increases, being
35.8° from the vertical for a 40° dip. The main break
over the seam at an angle from the vertical equal to half the dip.
Angle of repose - The
from horizontal at which a given material will rest on a given surface
without sliding or rolling.
Anthracite coal - Of
the four types of
coal, anthracite is the hardest and contains the highest heat value. It
is almost pure carbon and is used mainly for home heating and cooking.
In some developing countries, it is also used for industrial purposes.
Anticline - An upward
fold or arch of rock strata.
Aquifer - A
water-bearing bed of porous rock, often sandstone.
Arching - Fracture
processes around a mine opening, leading to stabilization by an arching
Area (of an airway) -
Average width multiplied by average height of airway, expressed in
Auger - A rotary
drill that uses a screw device to penetrate, break, and then transport
the drilled material (coal).
- All activities supportive of but not contributing directly to mining.
- Portion of main
ventilating current directed to face of dead end entry by means of an
auxiliary fan and tubing.
Azimuth - A surveying
references the angle measured clockwise from any meridian (the
established line of reference). The bearing is used to designate
direction. The bearing of a line is the acute horizontal angle between
the meridian and the line.
Back - The roof or
upper part in any underground mining cavity.
Mine waste or rock used to support the roof after coal removal.
Barren - Said of rock
or vein material
containing no minerals of value, and of strata without coal, or
containing coal in seams too thin to be workable.
Enclosing part of a mine to prevent inflow of noxious gasses from a
mine fire or an explosion.
Barrier - Something
that bars or keeps
out. Barrier pillars are solid blocks of coal left between two mines or
sections of a mine to prevent accidents due to inrushes of water, gas,
or from explosions or a mine fire.
Beam - A bar or
straight girder used to support a span of roof between two support
props or walls.
Beam building - The
creation of a
strong, inflexible beam by bolting or otherwise fastening together
several weaker layers. In coal mining this is the intended basis for
Bearing – A
surveying term used
to designate direction. The bearing of a line is the acute horizontal
angle between the meridian and the line. The meridian is an established
line of reference. Azimuths are angles measured clockwise from any
Bearing plate - A
plate used to distribute a given load. In roof bolting, the plate used
between the bolt head and the roof.
Bed - A stratum of
coal or other sedimentary deposit.
Belt conveyor - A
looped belt on which
coal or other materials can be carried and which is generally
constructed of flame-resistant material or of reinforced rubber or
Belt idler - A
roller, usually of
cylindrical shape, which is supported on a frame and which, in turn,
supports or guides a conveyor belt. Idlers are not powered but turn by
contact with the moving belt.
Belt take-up - A belt
under a conveyor belt and inby the drive pulley, kept under strong
tension parallel to the belt line. Its purpose is to automatically
compensate for any slack in the belting created by start-up, etc.
Bench - One of to or
more divisions of a coal seam separated by slate or formed by the
process of cutting the coal.
Beneficiation - The
treatment of mined material, making it more concentrated or richer.
Berm - A pile or
mound of material capable of restraining a vehicle.
Binder - A streak of
impurity in a coal seam.
Bit - The hardened
device at the end of a drill rod that transmits the energy of breakage
to the rock. The size of the bit determines the size of the hole. A bit
may be either detachable from or integral with its supporting drill rod.
– A middle rank
coal (between subbituminous and anthracite) formed by additional
pressure and heat on lignite. Usually has a high Btu value and may be
referred to as "soft coal." A general term descriptive of coal
intermediate in rank between sub-bituminous and anthracite and
including metallurgical coals. Low and medium volatile bituminous coals
are ranked by their carbon content, while high volatile bituminous
coals are ranked by their heating value.
Black damp - A term
to carbon dioxide. Strictly speaking, it is a mixture of carbon dioxide
and nitrogen. It is also applied to an atmosphere depleted of oxygen,
rather than having an excess of carbon dioxide.
Blasting agent - Any
material consisting of a mixture of a fuel and an oxidizer.
Blasting cap - A
detonator containing a
charge of detonating compound, which is ignited by electric current or
the spark of a fuse. Used for detonating explosives.
Blasting circuit -
used to fire electric detonators or to ignite an igniter cord by means
of an electric starter.
Bleeder or bleeder
entries - Special
air courses developed and maintained as part of the mine ventilation
system and designed to continuously move air-methane mixtures emitted
by the gob or at the active face away from the active workings and into
mine-return air courses. Alt: Exhaust ventilation lateral.
Boiler - A tank in
which water is heated or steam is generated.
Bolt torque - The
turning force in foot-pounds applied to a roof bolt to achieve an
Borehole - Any deep
or long drill-hole, usually associated with a diamond drill.
Bottom - Floor or
underlying surface of an underground excavation.
Boss - Any member of
ranks who is directly in charge of miners (e.g., "shift-boss,"
"face-boss," "fire-boss," etc.).
Box-type magazine - A
magazine used to store limited quantities of explosives or detonators
for short periods of time at locations in the mine which are convenient
to the blasting sites at which they will be used.
Brattice or brattice
Fire-resistant fabric or plastic partition used in a mine passage to
confine the air and force it into the working place. Also termed "line
brattice," "line canvas," or "line curtain."
Break line - The line
follows the rear edges of coal pillars that are being mined. The line
along which the roof of a coal mine is expected to break.
Breaker - A machine
which combines coal
crushing and screening. Normally consists of a rotating drum in which
coal is broken by gravity impact against the walls of the drum.
Breakthrough - A
passage for ventilation that is cut through the pillars between rooms.
Bridge carrier - A
mobile conveyor, about 10 meters long, used as an intermediate unit to
create a system of articulated conveyors between a mining machine and a
room or entry conveyor.
Bridge conveyor - A
short conveyor hung
from the boom of mining or lading machine or haulage system with the
other end attached to a receiving bin that dollies along a frame
supported by the room or entry conveyor, tailpiece. Thus, as the
machine boom moves, the bridge conveyor keeps it in constant connection
with the tailpiece.
Brow - A low place in
the roof of a mine, giving insufficient headroom.
Brushing - Digging up
the bottom or taking down the top to give more headroom in roadways.
British thermal unit. A
measure of the energy required to raise the temperature of one pound of
water one degree Fahrenheit.
Bug dust - The fine
particles of coal
or other material resulting form the boring or cutting of the coal face
by drill or machine.
Bump (or burst) - A
of the mine workings which is attributed to severe stresses in the rock
surrounding the workings.
Butt cleat - A short,
poorly defined vertical cleavage plane in a coal seam, usually at right
angles to the long face cleat.
Butt entry - A coal
mining term that
has different meanings in different locations. It can be synonymous
with panel entry, submain entry, or in its older sense it refers to an
entry that is "butt" onto the coal cleavage (that is, at right angles
to the face).
Cage - In a mine
shaft, the device, similar to an elevator car, that is used for
hoisting personnel and materials.
Calorific value - The
quantity of heat that can be liberated from one pound of coal or oil
measured in BTU's.
Cannel coal - A
block coal with a fine, even grain and a conchoidal fracture which has
a high percentage of hydrogen, burns with a long, yellow flame, and is
extremely easy to ignite.
Canopy - A protective
covering of a cab on a mining machine.
Cap - A miner's
safety helmet. Also, a
highly sensitive, encapsulated explosive that is used to detonate
larger but less sensitive explosives.
Cap block - A flat
piece of wood inserted between the top of the prop and the roof to
provide bearing support.
Car - A railway
wagon, especially any of the wagons adapted to carrying coal, ore, and
Car-dump - The
mechanism for unloading a loaded car.
Carbide bit - More
tungsten carbide. A cutting or drilling bit for rock or coal, made by
fusing an insert of molded tungsten carbide to the cutting edge of a
steel bit shank.
Carbon Dioxide - A
non-toxic radiative gas that is essential to plant and animal life. It
is also emitted as a result of burning organic materials, including
Cast - A directed
throw; in strip-mining, the overburden is cast from the coal to the
previously mined area.
Certified - Describes
a person who has passed an examination to do a required job.
Chain conveyor - A
conveyor on which
the material is moved along solid pans (troughs) by the action of
scraper crossbars attached to powered chains.
Chain pillar - The
pillar of coal left to protect the gangway or entry and the parallel
Charcoal - The
residue, primarily carbon, from the partial combustion of wood or other
Check curtain - Sheet
of brattice cloth hung across an airway to control the passage of the
Human-produced chemical compounds containing chlorine, fluorine and
carbon which are thought to be responsible for ozone-layer depletion.
CFCs also act as a radiative gas.
Chock - Large
hydraulic jacks used to support roof in longwall and shortwall mining
Clay vein - A body of
clay-like material that fills a void in a coal bed.
Cleat - The vertical
cleavage of coal seams. The main set of joints along which coal breaks
Clean Air Act
Amendments of 1990
– A comprehensive set of amendments to the federal law
the nation's air quality. The Clean Air Act was originally passed in
1970 to address significant air pollution problems in our cities. The
1990 amendments broadened and strengthened the original law to address
specific problems such as acid deposition, urban smog, hazardous air
pollutants and stratospheric ozone depletion.
Technologies – A
number of innovative, new technologies designed to use coal in a more
efficient and cost-effective manner while enhancing environmental
protection. Several promising technologies include: fluidized-bed
combustion, integrated gasification combined cycle, limestone injection
multi-stage burner, enhanced flue gas desulfurization (or "scrubbing"),
coal liquefaction and coal gasification.
Coal - A solid,
brittle, more or less
distinctly stratified combustible carbonaceous rock, formed by partial
to complete decomposition of vegetation; varies in color from dark
brown to black; not fusible without decomposition and very insoluble.
- Removal of sulphur from coal or coal gas.
Coal dust - Particles
of coal that can pass a No. 20 sieve.
– The conversion of coal into a gaseous fuel.
Coal mine - An area
of land and all
structures, facilities, machinery, tools, equipment, shafts, slopes,
tunnels, excavations, and other property, real or personal, placed
upon, under, or above the surface of such land by any person, used in
extracting coal from its natural deposits in the earth by any means or
method, and the work of preparing the coal so extracted, including coal
preparation facilities. British term is "colliery".
Coal reserves -
Measured tonnages of coal that have been calculated to occur in a coal
seam within a particular property.
– The process of
separating undesirable materials from coal based on differences in
densities. Pyritic sulfur, or sulfur combined with iron, is heavier and
sinks in water; coal is lighter and floats.
Coke – A
hard, dry carbon
substance produced by heating coal to a very high temperature in the
absence of air. Coke is used in the manufacture of iron and steel.
Collar - The term
applied to the
timbering or concrete around the mouth or top of a shaft. The beginning
point of a shaft or drill hole at the surface.
Colliery - British
name for coal mine.
precombustion coal cleaning technology in which coal particles attach
to air bubbles rising in a vertical column. The coal is then removed at
the top of the column.
Combustion chamber -
The part of a boiler in which fuel is burned.
Comminution - The
breaking, crushing, or grinding of coal, ore, or rock.
Competent rock - Rock
which, because of
its physical and geological characteristics, is capable of sustaining
openings without any structural support except pillars and walls left
during mining (stalls, light props, and roof bolts are not considered
Contact - The place
or surface where
two different kinds of rocks meet. Applies to sedimentary rocks, as the
contact between a limestone and a sandstone, for example, and to
metamorphic rocks; and it is especially applicable between igneous
intrusions and their walls.
Continuous miner - A
constantly extracts coal while it loads it. This is to be distinguished
from a conventional, or cyclic, unit which must stop the extraction
process in order for loading to commence.
Contour - An
imaginary line that connects all points on a surface having the same
– The first
fully-mechanized underground mining method involving the insertion of
explosives in a coal seam, the blasting of the seam, and the removal of
the coal onto a conveyor or shuttle car by a loading machine.
Conveyor - An
apparatus for moving
material from one point to another in a continuous fashion. This is
accomplished with an endless (that is, looped) procession of hooks,
buckets, wide rubber belt, etc.
– A cylinder sample
generally 1-5" in diameter drilled out of an area to determine the
geologic and chemical analysis of the overburden and coal.
Cover - The
overburden of any deposit.
Creep - The forcing
of pillars into
soft bottom by the weight of a strong roof. In surface mining, a very
slow movement of slopes downhill.
Crib - A roof support
of prop timbers
or ties, laid in alternate cross-layers, log-cabin style. It may or may
not be filled with debris. Also may be called a chock or cog.
Cribbing - The
construction of cribs or
timbers laid at right angles to each other, sometimes filled with
earth, as a roof support or as a support for machinery.
Crop coal - Coal at
the outcrop of the
seam. It is usually considered of inferior quality due to partial
oxidation, although this is not always the case.
Crossbar - The
horizontal member of a roof timber set supported by props located
either on roadways or at the face.
Crosscut - A
passageway driven between
the entry and its parallel air course or air courses for ventilation
purposes. Also, a tunnel driven from one seam to another through or
across the intervening measures; sometimes called "crosscut tunnel", or
"breakthrough". In vein mining, an entry perpendicular to the vein.
Cross entry - An
entry running at an angle with the main entry.
Crusher - A machine
for crushing rock
or other materials. Among the various types of crushers are the ball
mill, gyratory crusher, Handsel mill, hammer mill, jaw crusher, rod
mill, rolls, stamp mill, and tube mill.
machine - A machine,
usually used in coal, that will cut a 10- to 15-cm slot. The slot
allows room for expansion of the broken coal. Also applies to the man
who operates the machine and to workers engaged in the cutting of coal
by prick or drill.
Cycle mining - A
system of mining in
more than one working place at a time, that is, a miner takes a lift
from the face and moves to another face while permanent roof support is
established in the previous working face.
– A collective term for the sum of coal in both measured and
indicated resources and reserves.
Deposit - Mineral
deposit or ore
deposit is used to designate a natural occurrence of a useful mineral,
or an ore, in sufficient extent and degree of concentration to invite
Depth - The word
denotes vertical depth below the surface. In the case of incline shafts
and boreholes it may mean the distance reached from the beginning of
the shaft or hole, the borehole depth, or the inclined depth.
Specialized chemical or electronic instruments used to detect mine
Detonator - A device
containing a small
detonating charge that is used for detonating an explosive, including,
but not limited to, blasting caps, exploders, electric detonators, and
delay electric blasting caps.
Development mining -
Work undertaken to open up coal reserves as distinguished from the work
of actual coal extraction.
Diffusion - Blending
of a gas and air, resulting in a homogeneous mixture. Blending of two
or more gases.
Diffuser fan - A fan
mounted on a continuous miner to assist and direct air delivery from
the machine to the face.
Dilute - To lower the
a mixture; in this case the concentration of any hazardous gas in mine
air by addition of fresh intake air.
Dilution - The
contamination of ore with barren wall rock in stoping.
Dip - The inclination
of a geologic
structure (bed, vein, fault, etc.) from the horizontal; dip is always
measured downwards at right angles to the strike.
A large excavation
machine used in surface mining to remove overburden (layers of rock and
soil) covering a coal seam. The dragline casts a wire rope-hung bucket
a considerable distance, collects the dug material by pulling the
bucket toward itself on the ground with a second wire rope (or chain),
elevates the bucket, and dumps the material on a spoil bank, in a
hopper, or on a pile.
Drainage - The
process of removing surplus ground or surface water either by
artificial means or by gravity flow.
Draw slate - A soft
slate, shale, or
rock from approximately 1 cm to 10 cm thick and located immediately
above certain coal seams, which falls quite easily when the coal
support is withdrawn.
Drift - A horizontal
underground. A drift follows the vein, as distinguished from a crosscut
that intersects it, or a level or gallery, which may do either.
– An underground coal
mine in which the entry or access is above water level and generally on
the slope of a hill, driven horizontally into a coal seam.
Drill - A machine
percussion (hammering), or a combination of both to make holes. If the
hole is much over 0.4m in diameter, the machine is called a borer.
Drilling - The use of
such a machine to create holes for exploration or for loading with
Dummy - A bag filled
with sand, clay, etc., used for stemming a charged hole.
Dump - To unload;
specifically, a load
of coal or waste; the mechanism for unloading, e.g. a car dump
(sometimes called tipple); or, the pile created by such unloading, e.g.
a waste dump (also called heap, pile, tip, spoil pike, etc.).
- To connect with the ground to make the earth part of the circuit.
precipitator - An
electrical device for removing fine particles (fly ash) from combustion
gases prior to release from a power plant's stack.
Energy - The capacity
to do work; more
commonly used as an all-encompassing generic term describing fuel
sources used to provide power.
Energy mix - The
combination of sources
used to provide energy at any given time and place. Energy sources
include coal, oil, gas, water (hydro), uranium (nuclear), wind,
sunlight, geothermal, and others.
Entry - An
underground horizontal or
near-horizontal passage used for haulage, ventilation, or as a mainway;
a coal heading; a working place where the coal is extracted from the
seam in the initial mining; same as "gate" and "roadway," both British
Evaluation - The work
involved in gaining a knowledge of the size, shape, position and value
Exploration - The
search for mineral
deposits and the work done to prove or establish the extent of a
mineral deposit. Alt: Prospecting and subsequent evaluation.
Explosive - Any
rapidly combustive or
expanding substance. The energy released during this rapid combustion
or expansion can be used to break rock.
Extraction - The
process of mining and removal of cal or ore from a mine.
Face – The
exposed area of a coal bed from which coal is being extracted.
Face cleat - The
principal cleavage plane or joint at right angles to the stratification
of the coal seam.
Face conveyor - Any
conveyor used parallel to a working face which delivers coal into
another conveyor or into a car.
Factor of safety -
The ratio of the
ultimate breaking strength of the material to the force exerted against
it. If a rope will break under a load of 6000 lbs., and it is carrying
a load of 2000 lbs., its factor of safety is 6000 divided by 2000 which
Fall - A mass of roof
rock or coal which has fallen in any part of a mine.
Fan, auxiliary - A
small, portable fan used to supplement the ventilation of an individual
Fan, booster - A
large fan installed in the main air current, and thus in tandem with
the main fan.
Fan signal -
Automation device designed to give alarm if the main fan slows down or
Fault - A
slip-surface between two
portions of the earth's surface that have moved relative to each other.
A fault is a failure surface and is evidence of severe earth stresses.
Fault zone - A fault,
instead of being
a single clean fracture, may be a zone hundreds or thousands of feet
wide. The fault zone consists of numerous interlacing small faults or a
confused zone of gouge, breccia, or mylonite.
Feeder - A machine
that feeds coal onto a conveyor belt evenly.
Fill - Any material
that is put back in place of the extracted ore to provide ground
Fire damp - The
methane, CH4. Also, the explosive methane-air mixtures with between 5%
and 15% methane. A combustible gas formed in mines by decomposition of
coal or other carbonaceous matter, and that consists chiefly of methane.
Fissure - An
extensive crack, break, or fracture in the rocks.
– The part of the
carbon that remains behind when coal is heated in a closed vessel until
all of the volatile matter is driven off.
Flat-lying - Said of
deposits and coal seams with a dip up to 5 degrees.
Flight - The metal
strap or crossbar attached to the drag chain-and-flight conveyor.
Float dust - Fine
carried in suspension by air currents and eventually deposited in
return entries. Dust consisting of particles of coal that can pass
through a No. 200 sieve.
Floor - That part of
working upon which a person walks or upon which haulage equipment
travels; simply the bottom or underlying surface of an underground
Desulfurization – Any of
several forms of chemical/physical processes that remove sulfur
compounds formed during coal combustion. The devices, commonly called
"scrubbers," combine the sulfur in gaseous emissions with another
chemical medium to form inert "sludge" which must then be removed for
Combustion – A
process with a high degree of ability to remove sulfur from coal during
combustion. Crushed coal and limestone are suspended in the bottom of a
boiler by an upward stream of hot air. The coal is burned in this
bubbling, liquid-like (or "fluidized") mixture. Rather than released as
emissions, sulfur from combustion gases combines with the limestone to
form a solid compound recovered with the ash.
Fly ash –
The finely divided
particles of ash suspended in gases resulting from the combustion of
fuel. Electrostatic precipitators are used to remove fly ash from the
gases prior to the release from a power plant's smokestack.
Any assemblage of
rocks which have some character in common, whether of origin, age, or
composition. Often, the word is loosely used to indicate anything that
has been formed or brought into its present shape.
– Any naturally occurring fuel of an organic nature, such as
coal, crude oil and natural gas.
Fracture - A general
term to include
any kind of discontinuity in a body of rock if produced by mechanical
failure, whether by shear stress or tensile stress. Fractures include
faults, shears, joints, and planes of fracture cleavage.
Friable - Easy to
break, or crumbling naturally. Descriptive of certain rocks and
Fuse - A cord-like
substance used in
the ignition of explosives. Black powder is entrained in the cord and,
when lit, burns along the cord at a set rate. A fuse can be safely used
to ignite a cap, which is the primer for an explosive.
Gallery - A
horizontal or a nearly horizontal underground passage, either natural
– Any of various processes by which coal is turned into low,
medium, or high Btu gases.
gathering belt -
Any conveyor which is used to gather coal from other conveyors and
deliver it either into mine cars or onto another conveyor. The term is
frequently used with belt conveyors placed in entries where a number of
room conveyors deliver coal onto the belt.
Geologist - One who
constitution, structure, and history of the earth's crust, conducting
research into the formation and dissolution of rock layers, analyzing
fossil and mineral content of layers, and endeavoring to fix historical
sequence of development by relating characteristics to known geological
influences (historical geology).
engineering - The branch
of engineering that specializes in assessing the stability and strength
of soil and rock materials, as well as groundwater conditions. With
regard to mining, geotechnical engineering principles are used to
determine the appropriate design of mine features such as pit walls,
tunnels, and earthen embankments.
Gob - The term
applied to that part of
the mine from which the coal has been removed and the space more or
less filled up with waste. Also, the loose waste in a mine. Also called
Global climate change
– This term
usually refers to the gradual warming of the earth caused by the
greenhouse effect. Many scientists believe this is the result of
man-made emissions of greenhouse gases such as carbon dioxide,
chlorofluorocarbons (CFC) and methane, although there is no agreement
among the scientific community on this controversial issue.
Grain - In petrology,
that factor of
the texture of a rock composed of distinct particles or crystals which
depends upon their absolute size.
Greenhouse effect -
phenomenon that occurs when certain atmospheric gases (see greenhouse
gases) trap radiated heat in the atmosphere. The greenhouse effect
keeps the atmosphere warm and makes life on earth possible.
Grizzly - Course
screening or scalping
device that prevents oversized bulk material form entering a material
transfer system; constructed of rails, bars, beams, etc.
Ground control - The
final arresting of the closure of the walls of a mined area. The term
generally refers to measures taken to prevent roof falls or coal bursts.
Ground pressure - The
pressure to which
a rock formation is subjected by the weight of the superimposed rock
and rock material or by diastrophic forces created by movements in the
rocks forming the earth's crust. Such pressures may be great enough to
cause rocks having a low compressional strength to deform and be
squeezed into and close a borehole or other underground opening not
adequately strengthened by an artificial support, such as casing or
Gunite - A cement
applied by spraying to the roof and sides of a mine passage.
Haulage - The
horizontal transport of ore, coal, supplies, and waste. The vertical
transport of the same is called hoisting.
Haulageway - Any
underground entry or
passageway that is designed for transport of mined material, personnel,
or equipment, usually by the installation of track or belt conveyor.
Headframe - The
structure surmounting the shaft which supports the hoist rope pulley,
and often the hoist itself.
Heading - A vein
above a drift. An
interior level or airway driven in a mine. In longwall workings, a
narrow passage driven upward from a gangway in starting a working in
order to give a loose end.
Head section - A term
used in both belt
and chain conveyor work to designate that portion of the conveyor used
for discharging material.
Heaving - Applied to
the rising of the bottom after removal of the coal; a sharp rise in the
floor is called a "hogsback".
The unexcavated face
of exposed overburden and coal in a surface mine or in a face or bank
on the uphill side of a contour mine excavation.
– A highwall
mining system consists of a remotely controlled continuous miner which
extracts coal and conveys it via augers, belt or chain conveyors to the
outside. The cut is typically a rectangular, horizontal cut from a
highwall bench, reaching depths of several hundred feet or deeper.
Hogsback - A sharp
rise in the floor of a seam.
Hoist - A drum on
which hoisting rope is wound in the engine house, as the cage or skip
is raised in the hoisting shaft.
Hoisting - The
vertical transport coal or material.
hopper - A bin or
funnel that is loaded from the top and which discharges through a door
or chute at the bottom.
Horizon - In geology,
definite position or interval in the stratigraphic column or the scheme
of stratigraphic classification; generally used in a relative sense.
Horseback - A mass of
material with a slippery surface in the roof; shaped like a horse's
Hydraulic - Of or
pertaining to fluids
in motion. Hydraulic cement has a composition which permits it to set
quickly under water. Hydraulic jacks lift through the force transmitted
to the movable part of the jack by a liquid. Hydraulic control refers
to the mechanical control of various parts of machines, such as coal
cutters, loaders, etc., through the operation or action of hydraulic
– A class of
compounds containing hydrogen and carbon formed by the decomposition of
plant and animal remains, including coal, mineral oil, petroleum,
natural gas, paraffin, the fossil resins, and the solid bitumens
occurring in rocks. Gasoline is a mixture of hydrocarbons.
Inby - In the
direction of the working face.
Incline - Any entry
to a mine that is
not vertical (shaft) or horizontal (adit). Often incline is reserved
for those entries that are too steep for a belt conveyor (+17 degrees
-18 degrees), in which case a hoist and guide rails are employed. A
belt conveyor incline is termed a slope. Alt: Secondary inclined
opening, driven upward to connect levels, sometimes on the dip of a
deposit; also called "inclined shaft".
Incompetent - Applied
to strata, a
formation, a rock, or a rock structure not combining sufficient
firmness and flexibility to transmit a thrust and to lift a load by
resources – Coal
for which estimates of the rank, quality, and quantity have been
computed partly from sample analyses and measurements and partly from
reasonable geologic projections. The points of observation are * to 1 *
miles apart. Indicated coal is projected to extend as an * mile wide
belt that lies more than * mile from the outcrop or points of
observation or measurement.
resources – Coal in
unexplored extensions of the demonstrated resources for which estimates
of the quality and size are based on geologic evidence and projection.
Quantitative estimates are based largely on broad knowledge of the
geologic character of the deposit and for which there are few, if any,
samples or measurements. The estimates are based on an assumed
continuity or repletion of which there is geologic evidence; this
evidence may include comparison with deposits of similar type. Bodies
that are completely concealed may be included if there is specific
geologic evidence of their presence. The points of observation are 1 *
to 6 miles apart.
In situ - In the
natural or original
position. Applied to a rock, soil, or fossil when occurring in the
situation in which it was originally formed or deposited.
Intake - The passage
through which fresh air is drawn or forced into a mine or to a section
of a mine.
- A term used in
belt and chain conveyor network to designate a section of the conveyor
frame occupying a position between the head and foot sections.
Immediate roof - The
roof strata immediately above the coalbed, requiring support during the
excavation of coal.
Isopach - A line, on
a map, drawn
through points of equal thickness of a designated unit. Synonym for
isopachous line; isopachyte.
Jackleg - A
percussion drill used for
drifting or stoping that is mounted on a telescopic leg which has an
extension of about 2.5 m. The leg and machine are hinged so that the
drill need not be in the same direction as the leg.
A caltrop or other
object manufactured with one or more rounded or sharpened points, which
when placed or thrown present at least one point at such an angle that
it is peculiar to and designed for use in puncturing or damaging
vehicle tires. Jackrocks are commonly used during labor disputes.
Job Safety Analysis
(J.S.A.) - A job breakdown that gives a safe, efficient job procedure.
Joint - A divisional
plane or surface
that divides a rock and along which there has been no visible movement
parallel to the plane or surface.
Kettle bottom - A
smooth, rounded piece
of rock, cylindrical in shape, which may drop out of the roof of a mine
without warning. The origin of this feature is thought to be the
remains of the stump of a tree that has been replaced by sediments so
that the original form has been rather well preserved.
Kerf - The undercut
of a coal face.
Lamp - The electric
cap lamp worn for
visibility. Also, the flame safety lamp used in coal mines to detect
methane gas concentrations and oxygen deficiency.
Layout - The design
or pattern of the
main roadways and workings. The proper layout of mine workings is the
responsibility of the manager aided by the planning department.
Lift - The amount of
coal obtained from a continuous miner in one mining cycle.
Lignite - A low-rank
coal with a relatively high moisture content and relatively low
– The process of
converting coal into a synthetic fuel, similar in nature to crude oil
and/or refined products, such as gasoline.
Lithology - The
character of a rock
described in terms of its structure, color, mineral composition, grain
size, and arrangement of its component parts; all those visible
features that in the aggregate impart individuality of the rock.
Lithology is the basis of correlation in coal mines and commonly is
reliable over a distance of a few miles.
Load - To place
explosives in a drill hole. Also, to transfer broken material into a
Loading machine - Any
device for transferring excavated coal into the haulage equipment.
Loading pocket -
Transfer point at a shaft where bulk material is loaded by bin, hopper,
and chute into a skip.
– One of three
major underground coal mining methods currently in use. Employs a steal
plow, or rotation drum, which is pulled mechanically back and forth
across a face of coal that is usually several hundred feet long. The
loosened coal falls onto a conveyor for removal from the mine.
Loose coal - Coal
fragments larger in size than coal dust.
Low Sulphur coal -
Coal which has a
sulphur content generally ranging from 0.1 per cent to 1.0 per cent.
All western Canadian coal is low in sulphur.
Low voltage - Up to
and including 660 volts by federal standards.
Main entry - A main
haulage road. Where the coal has cleats, main entries are driven at
right angles to the face cleats.
Main fan - A
installed at the surface; operates by either exhausting or blowing to
induce airflow through the mine roadways and workings.
Manhole - A safety
hole constructed in
the side of a gangway, tunnel, or slope in which miner can be safe from
passing locomotives and car. Also called a refuge hole.
Man trip - A carrier
of mine personnel, by rail or rubber tire, to and from the work area.
Manway - An entry
used exclusively for
personnel to travel form the shaft bottom or drift mouth to the working
section; it is always on the intake air side in gassy mines. Also, a
small passage at one side or both sides of a breast, used as a
traveling way for the miner, and sometimes, as an airway, or chute, or
resources – Coal
for which estimates of the rank, quality, and quantity have been
computed from sample analyses and measurements from closely spaced and
geologically well-known sample sites, such as outcrops, trenches, mine
workings, and drill holes. The points of observation and measurement
are so closely spaced and the thickness and extent of coals are so well
defined that the tonnage is judged to be accurate within 20 percent of
true tonnage. Although the spacing of the points of observation
necessary to demonstrate continuity of the coal differs from region to
region according to the character of the coal beds, the points of
observation are no greater than * mile apart. Measured coal is
projected to extend as a *-mile wide belt from the outcrop or points of
observation or measurement.
A surveying term that
establishes a line of reference. The bearing is used to designate
direction. The bearing of a line is the acute horizontal angle between
the meridian and the line. Azimuths are angles measured clockwise from
Metallurgical coal -
The type of coal
which is converted to coke for use in manufacturing steel; often
referred to as coking coal.
Methane – A
gas formed naturally from the decay of vegetative matter, similar to
that which formed coal. Methane, which is the principal component of
natural gas, is frequently encountered in underground coal mining
operations and is kept within safe limits through the use of extensive
mine ventilation systems.
Methane monitor - An
instrument often mounted on a piece of mining equipment, that detects
and measures the methane content of mine air.
Mine development -
The term employed to
designate the operations involved in preparing a mine for ore
extraction. These operations include tunneling, sinking, cross-cutting,
drifting, and raising.
Mine mouth electric
plant – A coal burning electric-generating plant built near a
Miner - One who is
engaged in the
business or occupation of extracting ore, coal, precious substances, or
other natural materials from the earth's crust.
Mineral - An
occurring naturally in the earth's crust, with a distinctive set of
physical properties, and a definite chemical composition.
Mining Engineer - A
person qualified by
education, training, and experience in mining engineering. A trained
engineer with knowledge of the science, economics, and arts of mineral
location, extraction, concentration and sale, and the administrative
and financial problems of practical importance in connection with the
profitable conduct of mining.
Misfire - The
complete or partial failure of a blasting charge to explode as planned.
MSHA - Mine Safety
and Health Administration; the federal agency which regulates coal mine
health and safety.
Mud cap - A charge of
fired in contact with the surface of a rock after being covered with a
quantity of wet mud, wet earth, or sand, without any borehole being
used. Also termed adobe, dobie, and sandblast (illegal in coal mining).
Natural ventilation -
Ventilation of a mine without the aid of fans or furnaces.
Nip - Device at the
end of the trailing
cable of a mining machine used for connecting the trailing cable to the
trolley wire and ground.
Nitrogen oxides (NOx)
- Formed when
nitrogen (N2) combines with oxygen (O2) in the burning of fossil fuels,
from the natural degradation of vegetation, and from the use of
chemical fertilizers. A significant component of acid deposition and
photochemical smog. The primary source of nitrogen oxide emissions is
Open end pillaring -
A method of mining
pillars in which no stump is left; the pockets driven are open on the
gob side and the roof is supported by timber.
Outby; outbye -
Nearer to the shaft, and hence farther from the working face. Toward
the mine entrance. The opposite of inby.
Coal that appears at or near the surface.
Layers of soil and
rock covering a coal seam. In surface mining operations, overburden is
removed prior to mining using large equipment. When mining has been
completed, it is either used to backfill the mined areas or is hauled
to an external dumping and/or storage site.
- Enclosed airway which permits one air current to pass over (under)
another without interruption.
Ozone (O3) - A
bluish, toxic gas, with
a pungent odor, formed of three oxygen atoms rather than the usual two.
Occurs in the stratosphere and plays a role in filtering out
ultraviolet radiation from the sun's rays. At ground level ozone is a
major component of photochemical smog.
Panel - A coal mining
block that generally comprises one operating unit.
Panic bar - A switch,
in the shape of a bar, used to cut off power at the machine in case of
Parting - (1) A small
joint in coal or rock; (2) a layer of rock in a coal seam; (3) a side
track or turnout in a haulage road.
dark brown or black
deposit resulting from the partial decomposition of vegetative matter
in marshes, swamps and bogs. One of the earliest stages of coal
- The proportion
of a coal seam which is removed from the mine. The remainder may
represent coal in pillars or coal which is too thin or inferior to mine
or lost in mining. Shallow coal mines working under townships,
reservoirs, etc., may extract 50%, or less, of the entire seam, the
remainder being left as pillars to protect the surface. Under favorable
conditions, longwall mining may extract from 80 to 95% of the entire
seam. With pillar methods of working, the extraction ranges from 50 to
90% depending on local conditions.
Percussion drill - A
drill, usually air powered, that delivers its energy through a pounding
or hammering action.
Permissible - That
which is allowable
or permitted. It is most widely applied to mine equipment and
explosives of all kinds which are similar in all respects to samples
that have passed certain tests of the MSHA and can be used with safety
in accordance with specified conditions where hazards from explosive
gas or coal dust exist.
Permit – As
it pertains to
mining, a document issued by a regulatory agency that gives approval
for mining operations to take place.
Piggy-back - A bridge
Pillar - An area of
coal left to
support the overlying strata in a mine; sometimes left permanently to
support surface structures.
Pillar robbing - The
of the coal pillars between rooms or chambers to regulate the
subsidence of the roof. Also termed "bridging back" the pillar,
"drawing" the pillar, or "pulling" the pillar.
Pinch - A compression
of the walls of a vein or the roof and floor of a coal seam so as to
"squeeze" out the coal.
Pinch – A
compression of the roof and floor of a coal seam so as to "squeeze" out
Pinning - Roof
Pit Ponies - Small
horses, mules, or ponies which were used to pull coal shuttle cars from
underground mines during the 1800s.
Pitch - The
inclination of a seam; the rise of a seam.
Plan - A map showing
features such as mine workings or geological structures on a horizontal
Pneumoconiosis - A
chronic disease of the lung arising from breathing coal dust.
Portal - The
structure surrounding the immediate entrance to a mine; the mouth of an
adit or tunnel.
Portal bus -
Track-mounted, self-propelled personnel carrier that holds 8 to 12
Post - The vertical
member of a timber set.
Preparation plant - A
place where coal is cleaned, sized, and prepared for market.
Primary roof - The
main roof above the immediate top. Its thickness may vary from a few to
several thousand feet.
Primer (booster) - A
cartridge of explosive which is designed specifically to transmit
detonation to other explosives and which does not contain a detonator.
Prop - Coal mining
term for any single
post used as roof support. Props may be timber or steel; if
steel--screwed, yieldable, or hydraulic.
Proximate analysis -
A physical, or
non-chemical, test of the constitution of coal. Not precise, but very
useful for determining the commercial value. Using the same sample (1
gram) under controlled heating at fixed temperatures and time periods,
moisture, volatile matter, fixed carbon and ash content are
successfully determined. Sulfur and Btu content are also generally
reported with a proximate analysis.
Pyrite - A hard,
heavy, shiny, yellow
mineral, FeS2 or iron disulfide, generally in cubic crystals. Also
called iron pyrites, fool's gold, sulfur balls. Iron pyrite is the most
common sulfide found in coal mines.
Raise - A secondary
inclined opening, vertical or near-vertical opening driven upward form
a level to connect with the level above, or to explore the ground for a
limited distance above one level.
Ramp - A secondary or
opening, driven to connect levels, usually driven in a downward
direction, and used for haulage.
Ranks of coal
classification of coal by degree of hardness, moisture and heat
content. "Anthracite" is hard coal, almost pure carbon, used mainly for
heating homes. "Bituminous" is soft coal. It is the most common coal
found in the United States and is used to generate electricity and to
make coke for the steel industry. "Subbituminous" is a coal with a
heating value between bituminous and lignite. It has low fixed carbon
and high percentages of volatile matter and moisture. "Lignite" is the
softest coal and has the highest moisture content. It is used for
generating electricity and for conversion into synthetic gas. In terms
of Btu or "heating" content, anthracite has the highest value, followed
by bituminous, subbituminous and lignite.
– The restoration of
land and environmental values to a surface mine site after the coal is
extracted. Reclamation operations are usually underway as soon as the
coal has been removed from a mine site. The process includes restoring
the land to its approximate original appearance by restoring topsoil
and planting native grasses and ground covers.
Recovery - The
proportion or percentage of coal or ore mined from the original seam or
Red dog - A
product of the oxidation of coal or coal refuse. Most commonly applied
to material resulting from in situ, uncontrolled burning of coal or
coal refuse piles. It is similar to coal ash.
Regulator - Device
(wall, door) used to control the volume of air in an air split.
That portion of the
identified coal or mineral deposit resource that can be economically
mined at the time of determination. The reserve is derived by applying
a recovery factor to that component of the identified resource
designated as the reserve base or proven reserves.
Resin bolting - A
method of permanent roof support in which steel rods are grouted with
coal in such forms that economic extraction is currently or may become
feasible. Coal resources broken down by identified and undiscovered
resources. Identified coal resources are classified as demonstrated and
inferred. Demonstrated resources are further broken down as measured
and indicated. Undiscovered resources are broken down as hypothetical
Respirable dust -
Dust particles 5 microns or less in size.
sample - A sample
collected with an approved coal mine dust sampler unit attached to a
miner, or so positioned as to measure the concentration of respirable
dust to which the miner is exposed, and operated continuously over an
entire work shift of such miner.
Retreat mining - A
system of robbing
pillars in which the robbing line, or line through the faces of the
pillars being extracted, retreats from the boundary toward the shaft or
Return - The air or
ventilation that has passed through all the working faces of a split.
Return idler - The
idler or roller
underneath the cover or cover plates on which the conveyor belt rides
after the load which it was carrying has been dumped at the head
section and starts the return trip toward the foot section.
Rib - The side of a
pillar or the wall of an entry. The solid coal on the side of any
underground passage. Same as rib pillar.
Rider - A thin seam
of coal overlying a thicker one.
Ripper - A coal
extraction machine that works by tearing the coal from the face.
Rob - To extract
pillars of coal previously left for support.
Robbed out area -
Describes that part of a mine from which the pillars have been removed.
Roll - (1) A high
place in the bottom
or a low place in the top of a mine passage, (2) a local thickening of
roof or floor strata, causing thinning of a coal seam.
Roll protection - A
framework, safety canopy, or similar protection for the operator when
Roof - The stratum of
rock or other
material above a coal seam; the overhead surface of a coal working
place. Same as "back" or "top."
Roof bolt - A long
steel bolt driven
into the roof of underground excavations to support the roof,
preventing and limiting the extent of roof falls. The unit consists of
the bolt (up to 4 feet long), steel plate, expansion shell, and pal
nut. The use of roof bolts eliminates the need for timbering by
fastening together, or "laminating," several weaker layers of roof
strata to build a "beam."
Roof fall - A coal
mine cave-in especially in permanent areas such as entries.
Roof jack - A screw-
or pump-type hydraulic extension post made of steel and used as
temporary roof support.
Roof sag - The
sinking, bending, or curving of the roof, especially in the middle,
from weight or pressure.
Roof stress -
Unbalanced internal forces in the roof or sides, created when coal is
– Posts, jacks, roof
bolts and beams used to support the rock overlying a coal seam in an
underground mine. A good roof support plan is part of mine safety and
Roof trusses - A
combination of steel
rods anchored into the roof to create zones of compression and tension
forces and provide better support for weak roof and roof over wide
Room and pillar
mining – A method
of underground mining in which approximately half of the coal is left
in place to support the roof of the active mining area. Large "pillars"
are left while "rooms" of coal are extracted.
Room neck - The short
passage from the entry into a room.
Round - Planned
pattern of drill holes
fired in sequence in tunneling, shaft sinking, or stoping. First the
cut holes are fired, followed by relief, lifter, and rib holes.
Royalty - The payment
of a certain stipulated sum on the mineral produced.
Rubbing surface - The
total area (top, bottom, and sides) of an airway.
Run-of-mine - Raw
material as it exists in the mine; average grade or quality.
Safety fuse - A train
enclosed in cotton, jute yarn, or waterproofing compounds, which burns
at a uniform rate; used for firing a cap containing the detonation
compound which in turn sets off the explosive charge.
Safety lamp - A lamp
with steel wire
gauze covering every opening from the inside to the outside so as to
prevent the passage of flame should explosive gas be encountered.
Sampling - Cutting a
representative part of an ore (or coal) deposit, which should truly
represent its average value.
Sandstone - A
consisting of quartz sand united by some cementing material, such as
iron oxide or calcium carbonate.
Scaling - Removal of
loose rock from
the roof or walls. This work is dangerous and a long bar (called a
scaling bar)is often used.
Scoop - A rubber
tired-, battery- or diesel-powered piece of equipment designed for
cleaning runways and hauling supplies.
Any of several forms
of chemical/physical devices that remove sulfur compounds formed during
coal combustion. These devices, technically know as flue gas
desulfurization systems, combine the sulfur in gaseous emissions with
another chemical medium to form inert "sludge," which must then be
removed for disposal.
Seam - A stratum or
bed of coal.
Secondary roof - The
roof strata immediately above the coalbed, requiring support during the
excavating of coal.
Section - A portion
of the working area of a mine.
Selective mining -
The object of
selective mining is to obtain a relatively high-grade mine product;
this usually entails the use of a much more expensive stoping system
and high exploration and development costs in searching for and
developing the separate bunches, stringers, lenses, and bands of ore.
breathing apparatus - A
self-contained supply of oxygen used during rescue work from coal mine
fires and explosions; same as SCSR (self-contained self rescuer).
– A small filtering
device carried by a coal miner underground, either on his belt or in
his pocket, to provide him with immediate protection against carbon
monoxide and smoke in case of a mine fire or explosion. It is a small
canister with a mouthpiece directly attached to it. The wearer breathes
through the mouth, the nose being closed by a clip. The canister
contains a layer of fused calcium chloride that absorbs water vapor
from the mine air. The device is used for escape purposes only because
it does not sustain life in atmospheres containing deficient oxygen.
The length of time a self-rescuer can be used is governed mainly by the
humidity in the mine air, usually between 30 minutes and one hour.
The separation of a
mineral interest from other interests in the land by grant or
reservation. A mineral dead or grant of the land reserving a mineral
interest, by the landowner before leasing, accomplishes a severance as
does his execution of a mineral lease.
Shaft - A primary
non-vertical opening through mine strata used for ventilation or
drainage and/or for hoisting of personnel or materials; connects the
surface with underground workings.
– An underground mine in which the main entry or access is by
means of a vertical shaft.
Shale - A rock formed
of clay, mud, or silt, having a laminated structure and composed of
minerals essentially unaltered since deposition.
Shearer - A mining
machine for longwall
faces that uses a rotating action to "shear" the material from the face
as it progresses along the face.
Shift - The number of
hours or the part of any day worked.
An underground mining
method in which small areas are worked (15 to 150 feet) by a continuous
miner in conjunction with the use of hydraulic roof supports.
– A self-discharging
truck, generally with rubber tires or caterpillar-type treads, used for
receiving coal from the loading or mining machine and transferring it
to an underground loading point, mine railway or belt conveyor system.
Sinking - The process
by which a shaft is driven.
Skid - A
track-mounted vehicle used to
hold trips or cars from running out of control. Also it is a
flat-bottom personnel or equipment carrier used in low coal.
Skip - A car being
hoisted from a slope or shaft.
Slack - Small coal;
the finest-sized soft coal, usually less than one inch in diameter.
Slag - The waste
product of the process of smelting.
Slate - A miner's
term for any shale or
slate accompanying coal. Geologically, it is a dense, fine-textured,
metamorphic rock, which has excellent parallel cleavage so that it
breaks into thin plates or pencil-like shapes.
Slate bar - The
proper long-handled tool used to pry down loose and hazardous material
from roof, face, and ribs.
Slickenside - A
smooth, striated, polished surface produced on rock by friction.
Slip - A fault. A
smooth joint or crack where the strata have moved on each other.
Slope - Primary
inclined opening, connection the surface with the underground workings.
– An underground mine with an opening that slopes upward or
downward to the coal seam.
Sloughing - The slow
crumbling and falling away of material from roof, rib, and face.
Solid - Mineral that
has not been undermined, sheared out, or otherwise prepared for
Sounding - Knocking
on a roof to see whether it is sound and safe to work under.
Spad – A
spad is a flat spike
hammered into a wooden plug anchored in a hole drilled into the mine
ceiling from which is threaded a plumbline. The spad is an underground
survey station similar to the use of stakes in marking survey points on
the surface. A pointer spad, or sight spad, is a station that allows a
mine foreman to visually align entries or breaks from the main spad.
Span - The horizontal
distance between the side supports or solid abutments along sides of a
Specific gravity -
The weight of a substance compared with the weight of an equal volume
of pure water at 4 ° Celsius.
Split - Any division
or branch of the
ventilating current. Also, the workings ventilated by one branch. Also,
to divide a pillar by driving one or more roads through it.
Squeeze - The
breaking, of the roof and the gradual upheaval of the floor of a mine
due to the weight of the overlying strata.
Steeply inclined -
Said of deposits and coal seams with a dip of from 0.7 to 1 rad (40
degrees to 60 degrees).
Stemming - The
noncombustible material used on top or in front of a charge or
Strike - The
direction of the line of
intersection of a bed or vein with the horizontal plane. The strike of
a bed is the direction of a straight line that connects two points of
equal elevation on the bed.
– The unit amount
of overburden that must be removed to gain access to a similar unit
amount of coal or mineral material.
Stump - Any small
– Coal with an energy/heat value between lignite and
– The gradual sinking,
or sometimes abrupt collapse, of the rock and soil layers into an
underground mine. Structures and surface features above the subsidence
area can be affected.
Sump - The bottom of
a shaft, or any other place in a mine, that is used as a collecting
point for drainage water.
Sumping - To force
the cutter bar of a machine into or under the coal. Also called a
sumping cut, or sumping in.
Support - The
all-important function of
keeping the mine workings open. As a verb, it refers to this function;
as a noun it refers to all the equipment and materials--timber, roof
bolts, concrete, steel, etc.--that are used to carry out this function.
– A mine in which
the coal lies near the surface and can be extracted by removing the
covering layers of rock and soil.
Suspension - Weaker
strata hanging from stronger, overlying strata by means of roof bolts.
Syncline - A fold in
rock in which the strata dip inward from both sides toward the axis.
The opposite of anticline.
Tailgate - A
subsidiary gate road to a
conveyor face as opposed to a main gate. The tailgate commonly acts as
the return airway and supplies road to the face.
Tailpiece - Also
known as foot section
pulley. The pulley or roller in the tail or foot section of a belt
conveyor around which the belt runs.
Tail section - A term
used in both belt
and chain conveyor work to designate that portion of the conveyor at
the extreme opposite end from the delivery point. In either type of
conveyor it consists of a frame and either a sprocket or a drum on
which the chain or belt travels, plus such other devices as may be
required for adjusting belt or chain tension.
Tectonic forces -
Forces pertaining to, causing, or resulting from structural deformation
of the earth's crust.
Tension - The act of
Tertiary - Lateral or
panel openings (e.g., ramp, crosscut).
Thermal coal - A
generic term used to
describe coal which is used primarily to generate heat as opposed to
metallurgical coal which is converted to coke for use in steel
production. Sometimes referred to as steam coal.
Through-steel - A
system of dust
collection from rock or roof drilling. The drill steel is hollow, and a
vacuum is applied at the base, pulling the dust through the steel and
into a receptacle on the machine.
Timber - A collective
term for underground wooden supports.
Timbering - The
setting of timber supports in mine workings or shafts for protection
against falls from roof, face, or rib.
Timber set - A timber
frame to support the roof, sides, and sometimes the floor of mine
roadways or shafts.
Tipple - Originally
the place where the
mine cars were tipped and emptied of their coal, and still used in that
same sense, although now more generally applied to the surface
structures of a mine, including the preparation plant and loading
Ton – A
short or net ton is equal
to 2,000 pounds; a long or British ton is 2,240 pounds; a metric ton is
approximately 2,205 pounds.
Top - A mine roof;
same as "back."
Torque wrench - A
indicates, as on a dial, the amount of torque (in units of foot-pounds)
exerted in tightening a roof bolt.
Tractor - A
battery-operated piece of equipment that pulls trailers, skids, or
personnel carriers. Also used for supplies.
Tram - Used in
connection with moving
self-propelled mining equipment. A tramming motor may refer to an
electric locomotive used for hauling loaded trips or it may refer to
the motor in a cutting machine that supplies the power for moving or
tramming the machine.
Transfer - A vertical
or inclined connection between two or more levels and used as an ore
Transfer point -
Location in the
materials handling system, either haulage or hoisting, where bulk
material is transferred between conveyances.
Trip - A train of
Troughing idlers -
The idlers, located
on the upper framework of a belt conveyor, which support the loaded
belt. They are so mounted that the loaded belt forms a trough in the
direction of travel, which reduces spillage and increases the carrying
capacity of a belt for a given width.
Tunnel - A
near-horizontal, underground passage, entry, or haulageway, that is
open to the surface at both ends. A tunnel (as opposed to an adit) must
pass completely through a hill or mountain.
Ultimate analysis -
Precise determination, by chemical means, of the elements and compounds
Undercut - To cut
below or undermine
the coal face by chipping away the coal by pick or mining machine. In
some localities the terms "undermine" or "underhole" are used.
– Also known as
a "deep" mine. Usually located several hundred feet below the earth's
surface, an underground mine's coal is removed mechanically and
transferred by shuttle car or conveyor to the surface.
Underground station -
An enlargement of
an entry, drift, or level at a shaft at which cages stop to receive and
discharge cars, personnel, and material. An underground station is any
location where stationary electrical equipment is installed. This
includes pump rooms, compressor rooms, hoist rooms, battery-charging
– A long train of
between 60 and 150 or more hopper cars, dedicated to the transport of a
single commodity such as coal between a single mine and destination.
Universal coal cutter
- A type of coal
cutting machine which is designed to make horizontal cuts in a coal
face at any point between the bottom and top or to make shearing cuts
at any point between the two ribs of the place. The cutter bar can be
twisted to make cuts at any angle to the horizontal or vertical.
Upcast shaft - A
shaft through which air leaves the mine.
Valuation - The act
or process of valuing or of estimating the value or worth; appraisal.
Velocity - Rate of
airflow in lineal feet per minute.
Ventilation - The
provision of a
directed flow of fresh and return air along all underground roadways,
traveling roads, workings, and service parts.
Violation - The
breaking of any state or federal mining law.
Virgin - Unworked;
untouched; often said of areas where there has been no coal mining.
Void - A general term
for pore space or
other reopenings in rock. In addition to pore space, the term includes
vesicles, solution cavities, or any openings either primary or
Volatile matter - The
gaseous part, mostly hydrocarbons, of coal.
Waste - That rock or
mineral which must be removed from a mine to keep the mining scheme
practical, but which has no value.
Water Gauge (standard
U-tube) - Instrument that measures differential pressures in inches of
Wedge - A piece of
wood tapering to a thin edge and used for tightening in conventional
Weight - Fracturing
and lowering of the roof strata at the face as a result of mining
operations, as in "taking weight".
White damp - Carbon
monoxide, CO. A gas
that may be present in the afterdamp of a gas- or coal-dust explosion,
or in the gases given off by a mine fire; also one of the constituents
of the gases produced by blasting. Rarely found in mines under other
circumstances. It is absorbed by the hemoglobin of the blood to the
exclusion of oxygen. One-tenth of 1% (.001) may be fatal in 10 minutes.
Width - The thickness
of a lode measured at right angles to the dip.
Winning - The
excavation, loading, and removal of coal or ore from the ground;
winning follows development.
Winze - Secondary or
or near-vertical opening sunk from a point inside a mine for the
purpose of connecting with a lower level or of exploring the ground for
a limited depth below a level.
Wire rope - A steel
wire rope used for
winding in shafts and underground haulages. Wire ropes are made from
medium carbon steels. Various constructions of wire rope are designated
by the number of strands in the rope and the number of wires in each
strand. The following are some common terms encountered: airplane
strand; cablelaid rope; cane rope; elevator rope; extra-flexible
hoisting rope; flat rope; flattened-strand rope; guy rope; guy strand;
hand rope; haulage rope; hawser; hoisting rope; lang lay rope; lay;
left lay rope; left twist; nonspinning rope; regular lay; reverse-laid
rope; rheostat rope; right lay; right twist; running rope; special
flexible hoisting rope; standing rope; towing hawser; transmission rope.
Working - When a coal
seam is being
squeezed by pressure from roof and floor, it emits creaking noises and
is said to be "working". This often serves as a warning to the miners
that additional support is needed.
Working face - Any
place in a mine where material is extracted during a mining cycle.
Working place - From
the outby side of the last open crosscut to the face.
Workings - The entire
system of openings in a mine for the purpose of exploitation.
Working section -
From the faces to the point where coal is loaded onto belts or rail
cars to begin its trip to the outside.