Law + Mining
Entering the Stock Market
MINING LAWYER - FINANCING TERMS
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
Acid mine water
Mine water that contains free sulfuric acid, mainly due to the weathering of iron pyrites.
Any place in a mine where miners are normally
required to work or travel and which are ventilated and inspected
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.
Mining in the same direction, or order of sequence; first mining as
distinguished from retreat.
A family of
processes which can be used to concentrate valuable minerals
(including coal) based on their adhesive properties.
The division of a current of air into two or more parts.
Any passage through which air is carried. Also known as
an air course.
Instrument for measuring air
Angle of dip - The angle at which strata or mineral
deposits are inclined to the horizontal plane.
Angle of draw
- In coal mine 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 occurs
over the seam at an angle from the vertical equal to half the dip.
Angle of repose - The maximum angle from horizontal at which a
given material will rest on a given surface without sliding or
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
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 effect.
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).
Auxiliary operations - All activities supportive of but not
contributing directly to mining.
Auxiliary ventilation -
Portion of main ventilating current directed to face of dead end
entry by means of an auxiliary fan and tubing.
Azimuth - A
surveying term that 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
Backfill 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.
Barricading - 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 roof bolting.
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 meridian.
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
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
pulley, generally 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
Bench - One of to or more divisions of a coal
seam separated by slate or formed by the process of cutting the
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 and strengthened 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 generally applied 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 -
Electric circuits used to fire electric detonators or to ignite an
igniter cord by means of an electric starter.
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 installed
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
the managerial ranks who is directly in charge of miners (e.g.,
"shift-boss," "face-boss," "fire-boss," etc.).
magazine - A small, portable 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 cloth -
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."
- The line that roughly 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
Breakthrough - A passage for ventilation that is cut
through the pillars between rooms.
Bridge carrier - A
rubber-tire-mounted 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.
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
Brushing - Digging up the bottom or taking down the
top to give more headroom in roadways.
Btu 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 violent dislocation of the mine workings which is attributed to
severe stresses in the rock surrounding the workings.
cleat - A short, poorly defined vertical cleavage plane in a coal
seam, usually at right angles to the long face cleat.
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
Calorific value - The quantity of heat that can be
liberated from one pound of coal or oil measured in BTU's.
Cannel coal - A massive, non-caking 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
Canopy - A protective covering of a cab on a mining
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
Car - A railway wagon, especially any of the
wagons adapted to carrying coal, ore, and waste underground.
Car-dump - The mechanism for unloading a loaded car.
bit - More correctly, cemented 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 colorless, odorless, non-toxic radiative gas that
is essential to plant and animal life. It is also emitted as a
result of burning organic materials, including fossil fuels.
Cast - A directed throw; in strip-mining, the overburden is cast
from the coal to the previously mined area.
Describes a person who has passed an examination to do a required
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 airways.
Charcoal - The residue, primarily carbon, from the partial
combustion of wood or other organic matter.
Check curtain -
Sheet of brattice cloth hung across an airway to control the passage
of the air current.
Chlorofluorocarbons (CFCs) -
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
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 when
Clean Air Act Amendments of 1990 A comprehensive set
of amendments to the federal law governing 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
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
Coal desulphurisation - Removal of sulphur from
coal or coal gas.
Coal dust - Particles of coal that can pass
a No. 20 sieve.
Coal Gasification 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.
Coal washing 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.
Column flotation A 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 structural support).
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 machine that 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 elevation.
Conventional mining 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.
Core sample A
cylinder sample generally 1-5" in diameter drilled out of an area to
determine the geologic and chemical analysis of the overburden and
Cover - The overburden of any deposit.
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
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.
Cutter; Cutting 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.
Demonstrated reserves A collective term for the sum of coal in
both measured and indicated resources and reserves.
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 exploitation.
Depth - The
word alone generally 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.
Detectors - Specialized chemical or
electronic instruments used to detect mine gases.
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
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.
fan - A fan mounted on a continuous miner to assist and direct air
delivery from the machine to the face.
Dilute - To lower the
concentration of 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.
Dragline 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
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
Drift - A horizontal passage underground. A
drift follows the vein, as distinguished from a crosscut that
intersects it, or a level or gallery, which may do either.
Drift mine 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 utilizing
rotation, 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 explosives.
Dummy - A bag filled with sand, clay, etc., used for stemming a
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.).
Electrical grounding - To connect with
the ground to make the earth part of the circuit.
Electrostatic 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 terms.
Evaluation - The
work involved in gaining a knowledge of the size, shape, position
and value of coal.
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
Face cleat - The principal cleavage plane or joint
at right angles to the stratification of the coal seam.
conveyor - Any conveyor used parallel to a working face which
delivers coal into another conveyor or into a car.
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 equals 3.
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 working place.
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 stops.
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
Feeder - A machine that feeds coal onto a conveyor
Fill - Any material that is put back in place of
the extracted ore to provide ground support.
Fire damp - The
combustible gas, 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.
Fixed carbon 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
Flight - The metal strap or crossbar attached to the
drag chain-and-flight conveyor.
Float dust - Fine coal-dust
particles 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
any underground working upon which a person walks or upon which
haulage equipment travels; simply the bottom or underlying surface
of an underground excavation.
Flue Gas 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 disposal.
Fluidized Bed 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.
Formation 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.
Fossil fuel 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
Friable - Easy to break, or crumbling
naturally. Descriptive of certain rocks and minerals.
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 or artificial.
Gasification Any of various
processes by which coal is turned into low, medium, or high Btu
Gathering conveyor; 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 studies the 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).
Geotechnical 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
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
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 - The natural 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 regulation and 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.
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 timber.
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
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
Highwall miner 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
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, any given definite position or interval in
the stratigraphic column or the scheme of stratigraphic
classification; generally used in a relative sense.
- A mass of material with a slippery surface in the roof; shaped
like a horse's back.
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 cylinders.
Hydrocarbon 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".
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 bending.
Indicated coal 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.
coal 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.
Intermediate section - 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;
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.
Jackrock 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.
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.
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.
- A low-rank coal with a relatively high moisture content and
relatively low heat/energy content.
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 haulage device.
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.
Longwall Mining 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
Loose coal - Coal fragments larger in size than coal
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 mechanical ventilator 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
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 both.
Measured coal 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.
Meridian - 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 any meridian.
Metallurgical coal -
The type of coal which is converted to coke for use in manufacturing
steel; often referred to as coking coal.
potentially explosive 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 electronic 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 coal
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
inorganic compound occurring naturally in the earth's crust, with a
distinctive set of physical properties, and a definite chemical
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.
The complete or partial failure of a blasting charge to explode as
MSHA - Mine Safety and Health Administration; the
federal agency which regulates coal mine health and safety.
Mud cap - A charge of high explosive 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.
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 automobile exhaust.
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.
Outcrop Coal that appears at or near the
Overburden 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.
Overcast (undercast) - Enclosed
airway which permits one air current to pass over (under) another
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
Panic bar - A switch, in the shape of a bar,
used to cut off power at the machine in case of an emergency.
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.
Peat A 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 formation.
extraction - 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
Permit As it pertains to mining, a document issued
by a regulatory agency that gives approval for mining operations to
Piggy-back - A bridge conveyor.
An area of coal left to support the overlying strata in a mine;
sometimes left permanently to support surface structures.
Pillar robbing - The systematic removal 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
Pinch A compression of the roof and floor of a coal
seam so as to "squeeze" out the coal.
Pinning - Roof bolting.
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 plane.
Pneumoconiosis - A chronic
disease of the lung arising from breathing coal dust.
- 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 people.
Post - The vertical member of a timber set.
- 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 package or 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.
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 or tertiary 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 tertiary inclined opening, driven to
connect levels, usually driven in a downward direction, and used for
Ranks of coal The 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.
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
Recovery - The proportion or percentage of
coal or ore mined from the original seam or deposit.
- A nonvolatile combustion 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
Regulator - Device (wall, door) used to control the
volume of air in an air split.
Reserve 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 resin.
Resources Concentrations of
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 and speculative.
Respirable dust - Dust particles 5 microns or less in size.
Respirable dust 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 mine mouth.
Return - The air or ventilation that
has passed through all the working faces of a split.
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.
out area - Describes that part of a mine from which the pillars have
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.
protection - A framework, safety canopy, or similar protection for
the operator when equipment overturns.
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 extracted.
Roof support 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 coal extraction.
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 areas.
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
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 of powder 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
Sampling - Cutting a representative part of
an ore (or coal) deposit, which should truly represent its average
Sandstone - A sedimentary rock consisting of quartz
sand united by some cementing material, such as iron oxide or
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.
Scrubber 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.
Self-contained breathing apparatus
- A self-contained supply of oxygen used during rescue work from
coal mine fires and explosions; same as SCSR (self-contained self
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.
Severance 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 vertical or
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.
Shaft mine An
underground mine in which the main entry or access is by means of a
Shale - A rock formed by consolidation 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.
Shortwall 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.
Shuttle car 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.
Small coal; the finest-sized soft coal, usually less than one inch
Slag - The waste product of the process of
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.
- A fault. A smooth joint or crack where the strata have moved on
Slope - Primary inclined opening, connection the
surface with the underground workings.
Slope mine 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 roadway.
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 settling, without breaking, of the roof and the
gradual upheaval of the floor of a mine due to the weight of the
Steeply inclined - Said of deposits and
coal seams with a dip of from 0.7 to 1 rad (40 degrees to 60
Stemming - The noncombustible material used on top
or in front of a charge or explosive.
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.
ratio 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 pillar.
Sub-bituminous coal Coal with an
energy/heat value between lignite and bituminous.
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.
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.
Surface mine A mine in
which the coal lies near the surface and can be extracted by
removing the covering layers of rock and soil.
Weaker strata hanging from stronger, overlying strata by means of
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
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.
- 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,
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
Timber - A collective term for underground
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 tracks.
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 wrench
that 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 pass.
Transfer point - Location in
the materials handling system, either haulage or hoisting, where
bulk material is transferred between conveyances.
Trip - A
train of mine cars.
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 horizontal, or 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
- Precise determination, by chemical means, of the elements and
compounds in coal.
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.
Underground mine 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 rooms, etc.
Unit train 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
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
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.
Unworked; untouched; often said of areas where there has been no
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.
That rock or mineral which must be removed from a mine to keep the
mining scheme practical, but which has no value.
(standard U-tube) - Instrument that measures differential pressures
in inches of water.
Wedge - A piece of wood tapering to a
thin edge and used for tightening in conventional timbering.
Weight - Fracturing and lowering of the roof strata at the face as a
result of mining operations, as in "taking weight".
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
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 tertiary vertical 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
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;
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
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.