coal glossary

Question 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; (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

Answer 1

Abutment

Question 2

coal deposits that have been prepared for mining by construction of portals,
shafts, slopes, drifts, and haulage ways; by removal of overburden; or by partial
mining

Answer 2

Accessed

Question 3

: a mixture of wet and dry deposition (deposited material) from the atmosphere containing higher than typical amount of nitric and
sulfuric acids

Answer 3

Acid deposition or acid rain

Question 4

the volume of coal that covers 1 acre at a thickness of 1 ft
(43,560 ft3; 1,613.333 yd3; 1,233.482 m3). The weight of coal in this volume
varies according to rank

Answer 4

Acre-foot (acre-ft)

Question 5

: the volume of coal that covers 1 acre at a thickness of 1 in.
(3,630 ft3; 134.44 yd3; 102.7903 m3). The weight of coal in this volume varies
according to rank.

Answer 5

Acre-inch (acre-in.):

Question 6

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

Answer 6

Adit

Question 7

: mining in the same direction, or order of sequence; first mining as distinguished from retreat.

Answer 7

Advance:

Question 8

: formation of larger coal or ash particles by smaller particles sticking
together.

Answer 8

Agglomeration:

Question 9

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.

Answer 9

Angle of draw:

Question 10

e heaviest distillable coal tar fraction, with distillation range
270–400 ∘C (520–750 ∘F), containing creosote oil, anthracene, phenanthrene,
carbazole, and so on

Answer 10

Anthracene oil

Question 11

US Bureau of Mines term for vitrinite viewed by transmitted light.

Answer 11

Anthraxylon

Question 12

constituents of interest are silica (SiO2) alumina (Al2O3), titania (TiO2), ferric oxide (Fe2O3), lime (CaO), magnesia (MgO), potassium oxide
(K2O), sodium oxide (Na2O), and sulfur trioxide (SO3)

Answer 12

ash constituents

Question 13

the moisture present in a coal sample when delivered.

Answer 13

As-received moisture

Question 14

represents an analysis of a sample as received at a laboratory.

Answer 14

As-received basis

Question 15

a microscopic coal constituent composed of macerated plant debris
intimately mixed with mineral matter and coalified. US Bureau of Mines usage,
viewed by transmitted light.

Answer 15

Attritus

Question 16

the roof or upper part in any underground mining cavity

Answer 16

Back

Question 17

operation of refilling an excavation. Moreover, the material placed in an
excavation in the process of

Answer 17

Backfill

Question 18

an air pollution control device that removes particulate matter from flue
gas, usually achieving a removal rate above 99.9%.

Answer 18

Baghouse:

Question 19

: liquid volume measure equal to 42 US gals, commonly used in measuring
petroleum or petroleum products.

Answer 19

Barrel:

Question 20

enclosing part of a mine to prevent inflow of noxious gasses from a
mine fire or an explosion

Answer 20

Barricading

Question 21

a bar or straight girder used to support a span of roof between two support
props or walls.

Answer 21

Beam

Question 22

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

Answer 22

Bearing

Question 23

a dome-shaped oven not equipped to recover the by-product gas and
liquids evolved during the coking process.

Answer 23

Beehive oven

Question 24

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 rubber-like substance

Answer 24

Belt conveyor

Question 25

a crawler-mounted surge bin often equipped with a
crusher or breaker and used in room-and-pillar sections positioned at the end of the section conveyor belt. It allows a quick discharge of the shuttle car. It sizes the
coal and a built-in conveyor feeds it at an appropriate rate onto the conveyor belt.

Answer 25

Belt Feeder (Feeder breaker):

Question 26

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.

Answer 26

Belt idler

Question 27

treatment of mined material, making it more concentrated or
richer

Answer 27

Beneficiation

Question 28

a streak of impurity in a coal seam

Answer 28

Binder:

Question 29

high in carbonaceous matter, having less than 86% fixed carbon, and
more than 14% volatile matter on a dry, mineral-matter-free basis and more
than 10,500 Btu on a moist, mineral-matter-free basis. This class may be either
agglomerating or non-agglomerating and is divisible into the high-volatile C, B,
A; medium; and low volatile bituminous coal groups on the basis of increasing
heat content and fixed carbon and decreasing volatile matter

Answer 29

Bituminous (soft) coal

Question 30

a deadly gas that is caused from coal burning in an atmosphere which
lacks oxygen; mostly a mixture of carbon dioxide and nitrogen found in mines
after fires and explosions.

Answer 30

Blackdamp

Question 31

a respiratory disease caused by prolonged inhalation of
coal dust

Answer 31

Black lung (anthracosis)

Question 32

va detonator containing a charge of detonating compound, which is
ignited by electric current or the spark of a fuse. Used for detonating explosives

Answer 32

Blasting cap

Question 33

: a mixture consisting chiefly of carbon monoxide and hydrogen formed by
action of steam on hot coal or coke

Answer 33

Blue gas

Question 34

same as cannel coal except that algal remains can be seen under the
microscope.

Answer 34

Boghead coal

Question 35

: a molten ash collected at the base of slag tap and cyclone boilers that
is quenched with water and shatters into black, angular particles having a smooth
glassy appearance.

Answer 35

Boiler slag

Question 36

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

Answer 36

Brattice or brattice cloth:

Question 37

passage for ventilation that is cut through the pillars between
rooms.

Answer 37

Breakthrough

Question 38

a rubber-tire-mounted mobile conveyor, about 10 m long, used as
an intermediate unit to create a system of articulated conveyors between a mining
machine and a room or entry conveyor.

Answer 38

Bridge carrier

Question 39

US Bureau of Mines term for a combination of clarain and vitrain with
small amounts of fusain

Answer 39

Bright coal

Question 40

a process of applying pressure to coal fines, with or without a binder,
to form a compact or agglomerate

Answer 40

Briquetting

Question 41

the quantity of heat required to raise the temperature of
one pound of water one ∘F at, or near, its point of maximum density of 39.1 ∘F
(equivalent to 251.995 g calories; 1,054.35 J; 1.05435 kJ; 0.25199 kcal).

Answer 41

British thermal unit (Btu)

Question 42

a low place in the roof of a mine, giving insufficient headroom.

Answer 42

Brow:

Question 43

the fine particles of coal or other material resulting from the boring or
cutting of the coal face by drill or machine

Answer 43

Bug dust

Question 43

: digging up the bottom or taking down the top to give more headroom in
roadways

Answer 43

Brushing

Question 44

violent dislocation of the mine workings which is attributed to
severe stresses in the rock surrounding the workings

Answer 44

Bump (or burst)

Question 45

a short, poorly defined vertical cleavage plane in a coal seam, usually at
right angles to the long face cleat

Answer 45

Butt cleat

Question 46

e quantity of heat required to raise 1 g of water from 15 to 16 ∘C; a calorie
is also termed gram calorie or small calorie (equivalent to 0.00396832 Btu; 4.184 J;
0.001 kg calorie).

Answer 46

Calorie:

Question 47

the quantity of heat that can be liberated from one pound of coal or
oil measured in Btu/lb.

Answer 47

Calorific value

Question 48

predominately durain with lesser amounts of vitrain than splint coal
and small quantities of fusain. Spores can be seen under the microscope.

Answer 48

Cannel coal

Question 49

a flat piece of wood inserted between the top of the prop and the roof to
provide bearing support

Answer 49

Cap block

Question 50

: a process whereby coal is converted to coke by devolatilization.

Answer 50

Carbonization

Question 51

: a directed throw; in strip-mining, the overburden is cast from the coal to the
previously mined area

Answer 51

Cast

Question 52

a conveyor on which the material is moved along solid pans
(troughs) by the action of scraper crossbars attached to powered chains

Answer 52

Chain conveyor

Question 53

the pillar of coal left to protect the gangway or entry and the parallel
airways.

Answer 53

Chain pillar

Question 54

large hydraulic jacks used to support roof in longwall and shortwall mining
systems

Answer 54

Chock

Question 55

a macroscopic coal constituent (lithotype) known as bright-banded coal,
composed of alternating bands of vitrain and durain

Answer 55

Clarain

Question 56

: a fissure that has been infilled as a result of gravity, downward-percolating
ground waters, or compactional pressures which cause unconsolidated clays or
thixotropic sand to flow into the fissure

Answer 56

Clay vein

Question 57

natural opening-mode fractures in coal beds which account for most of the
permeability and much of the porosity of coalbed gas reservoirs

Answer 57

Cleats:

Question 58

particles of coal that can pass a No. 20 sieve.

Answer 58

Coal dust

Question 59

: strata containing one or more coal beds.

Answer 59

Coal measures

Question 60

a recombined coalbed sample produced by averaging together
thickness-weighted coal analyses from partial samples of the coalbed, such as from
one or more bench samples, from one or more mine exposures or outcrops where
the entire bed could not be accessed in one sample, or from multiple drill cores
that were required to retrieve all local sections of a coal seam.

Answer 60

Composite sample

Question 61

Any
partings greater than 3/8 in. and/or mineral concretions greater than 1/2 in. thick
and 2 in. in maximum diameter are normally discarded from a channel sample so as better to represent coal that has been mined, crushed, and screened to remove
at least gross non-coal materials.

Answer 61

Face channel or channel sample

Question 62

the condensable distillate containing light, middle, and heavy oils obtained
by carbonization of coal. About 8 gal of tar is obtained from each ton of bituminous
coal

Answer 62

Coal tar:

Question 63

also refer to gasification and liquefaction processes in which the coal is upgraded to a gaseous or
liquid product

Answer 63

refined coal

Question 64

: a series of laterally extensive and (or) lenticular coal beds and associated
strata that arbitrarily can be viewed as a unit; generally, the coal beds in a coal
zone are assigned to the same geologic member or formation

Answer 64

Coal zone

Question 65

coal pieces larger than 1/2 mm in size

Answer 65

Coarse coal

Question 66

a process by which electricity and steam, for space heating or
industrial-process heating, are produced simultaneously from the same fuel.

Answer 66

Cogeneration

Question 67

a gray, hard, porous, and coherent cellular-structured combustible solid, primarily composed of amorphous carbon; produced by destructive distillation or
thermal decomposition of certain bituminous coal that passes through a plastic
state in the absence of air.

Answer 67

Coke:

Question 68

British name for coal mine

Answer 68

Colliery:

Question 69

: breaking, crushing, or grinding of coal, ore, or rock.

Answer 69

Comminution

Question 70

a coal or a blend of coals that meets sulfur dioxide emission standards for air quality without the need for flue gas desulfurization

Answer 70

Compliance coal

Question 71

a volume of sedimentary rock in which mineral cement fills the spaces
between the sediment grains; often ovoid or spherical in shape, although irregular
shapes also occur

Answer 71

Concretion

Question 72

a mechanical mining machine consisting of a cutting head,
a coal-gathering device, a chain conveyor with flexible loading boom, and a
crawler-equipped chassis. Its function is to excavate the mineral and to load it
onto shuttle cars or continuous-haulage systems. It is electrically powered, with a
hydraulic subsystem for auxiliary functions. Power is supplied through a trailing
cable

Answer 72

Continuous miner:

Question 73

the removal of overburden and mining from
a coal seam that outcrops or approaches the surface at approximately the same
elevation in steep or mountainous areas

Answer 73

Contour mining (contour stripping)

Question 74

: 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 and is also may be called a chock or
cog.

Answer 74

Crib

Question 75

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

Answer 75

Cribbing

Question 76

coal at the outcrop of the seam; usually considered to be of inferior quality
due to partial oxidation, but this is not always the case.

Answer 76

Crop coal:

Question 77

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

Answer 77

Crosscut

Question 78

an entry running at an angle with the main entry

Answer 78

Cross entry

Question 79

a machine, usually used in coal, that will cut a 10–to
15-cm slot which 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

Answer 79

Cutter, Cutting machine

Question 80

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.

Answer 80

Cycle mining

Question 81

: a cone-shaped air-cleaning apparatus which operates by centrifugal separation that is used in particle collecting and fine grinding operation

Answer 81

Cyclone

Question 82

an equipment in which centrifugal force is used to separate particulates from a gas stream

Answer 82

Cyclone collectors

Question 83

refers to slagging combustion of coarsely pulverized coal in a cylindrical (cyclone) burner. Some wet-bottom boilers are not cyclone-fired. The primary by-product is a glassy slag referred to as boiler sl

Answer 83

Cyclone firing

Question 84

a collective term for the sum of coal in both measured and
indicated resources and reserves.

Answer 84

Demonstrated reserves

Question 85

a dense slurry formed by the suspension of heavy particles in water;
used to clean coal

Answer 85

Dense medium

Question 86

gravity downflow of packed solids contacted with
upwardly flowing gases—sometimes referred to as fixed-bed or moving-bed
system

Answer 86

Descending-bed system:

Question 87

work undertaken to open up coal reserves as distinguished
from the work of actual coal extraction

Answer 87

Development mining

Question 88

the removal of vaporizable material by the action of heat

Answer 88

Devolatilization

Question 89

: blending of a gas and air, resulting in a homogeneous mixture; blending
of two or more gases

Answer 89

Diffusion:

Question 90

: 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.

Answer 90

Dilute:

Question 91

fan mounted on a continuous miner to assist and direct air delivery
from the machine to the face

Answer 91

Diffuser fan

Question 92

: hydrogenation of coal without use of a separate donor solvent
hydrogenation step.

Answer 92

Direct hydrogenation

Question 93

the contamination of ore with barren wall rock in stopping.

Answer 93

Dilution

Question 94

air forced down into the mine below, by way of the airshaft which is
adjacent to the escape shaft.

Answer 94

Downcast:

Question 95

the process of removing surplus ground or surface water either by artificial
means or by gravity flow.

Answer 95

Drainage

Question 96

a soft slate, shale, or rock from approximately 1–10 cm thick and located
immediately above certain coal seams, which falls quite easily when the coal support is withdraw

Answer 96

Draw slate

Question 97

t follows the vein, as distinguished
from a crosscut that intersects it, or a level or gallery, which may do either. horizontal passage underground

Answer 97

Drift

Question 98

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.

Answer 98

Drift mine

Question 99

; if the hole is much over 0.4 m in diameter, the machine is called

Answer 99

borer.

Question 100

a coal analysis basis calculated as if moisture and ash were
removed

Answer 100

Dry, ash-free (daf) basis

Question 101

a bag filled with sand, clay, etc., used for stemming a charged hole

Answer 101

Dummy

Question 102

a system similar to a fluidized bed but operated at higher
gas velocities, such that a portion of the solids is carried out with the up-flowing
gas.

Answer 102

Ebullating-bed reactor

Question 103

: a process in which heat is absorbed

Answer 103

Endothermic reaction

Question 104

the moisture capacity of coal at 30 ∘C (86 ∘F) in an atmosphere of 95% relative humidity

Answer 104

Equilibrium moisture

Question 105

: a microscopic coal constituent (maceral) or maceral group containing spores
and cuticles. Appears dark gray in reflected light.

Answer 105

Exinite:

Question 106

a process in which heat is evolved.

Answer 106

Exothermic reaction

Question 107

the solid unbroken surface of a coal bed that is at the advancing end of the mine
workplace

Answer 107

Face

Question 108

: the principal cleavage plane or joint at right angles to the stratification of
the coal seam

Answer 108

Face cleat

Question 109

a conveyor used on longwall mining faces and consisting of a metal
trough with an integrated return channel. Steel scrapers attached to an endless
round link or roller-type chain force through the trough any material deposited
inside the trough by the mining machine. Spill plates and guides for mining equipment are attached. For flexibility and ease of installation the conveyor is made up
of 5-ft sections. Commonly, two electrically powered drives (one on each end)
move chain, scrapers (flights), and material along

Answer 109

Face conveyor

Question 110

hydraulically powered units used to support the roof along a longwall
face. They consist of plates at the roof and floor and 2–6 hydraulic cylinders that
press these plates against the respective surfaces with forces of 200–800 tons

Answer 110

Face supports

Question 111

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 lb, and it is
carrying a load of 2000 lb, its factor of safety is 3 (6000 divided 2000).

Answer 111

Factor of safety:

Question 112

a small, portable fan used to supplement the ventilation of an individual working place.

Answer 112

Fan, auxiliary

Question 113

an automation device designed to give alarm if the main fan slows down
or stops

Answer 113

Fan signal:

Question 114

unburned coal, ash, and spent bed material used for sulfur control.
The spent bed material (removed as bottom ash) contains reaction products from
the absorption of gaseous sulfur oxides (SO2 and SO3)

Answer 114

FBC materials

Question 115

derived from a variety of processes used to control sulfur emissions from boiler stacks. These systems include wet scrubbers, spray dry scrubbers, sorbent injectors, and a combined sulfur oxide (SOx) and nitrogen oxide
(NOx) process. Sorbents include lime, limestone, sodium-based compounds, and
high-calcium coal fly ash.

Answer 115

FGD materials

Question 116

typically any material that is put back in place of the extracted coal—sometimes
to provide ground support.

Answer 116

Fill

Question 117

: coal pieces less than 1/2 mm in size

Answer 117

Fine coal

Question 118

the content of fine particles, usually less than c in., in a coal sample

Answer 118

Fines

Question 119

an explosive mixture of carbonaceous gases, mainly methane, formed in
coal mines by the decomposition of coal

Answer 119

Firedamp

Question 120

the combustible residue left after the volatile matter is driven off. In
general, the fixed carbon represents that portion of the fuel that must be burned in
the solid state.

Answer 120

Fixed carbon

Question 121

: separation of crushed coal into density fractions using a
series of heavy liquids. Each fraction is weighed and analyzed for ash and often
for sulfur content. Washability curves are prepared from these data

Answer 121

Float-and-sink analysis

Question 122

water-soluble or colloidal chemical reagents that when added to finely
dispersed suspensions of solids in water, promote the formation of flocs of the
particles and their rapid settlement

Answer 122

Flocculants:

Question 123

: the removal of sulfur oxides

Answer 123

Flue gas desulfurization (FGD or scrubbing)

Question 124

removal of the sulfur gases from the flue gases
(stack gases) of a coal-fired boiler—typically using a high-calcium sorbent such
as lime or limestone. The three primary types of FGD processes commonly used
by utilities are wet scrubbers, dry scrubbers, and sorbent injection

Answer 124

Flue gas desulfurization (FGD)

Question 125

the degree of plasticity exhibited by a sample of coal heated in the absence
of air under controlled conditions, as described in ASTM Standard Test Methods
D1812 and D2639.

Answer 125

Fluidity

Question 126

accomplishes coal combustion by mixing the
coal with a sorbent such as limestone or other bed material. The fuel and bed
material mixture is fluidized during the combustion process to allow complete
combustion and removal of sulfur gases. Atmospheric FBC (AFBC) systems
may be bubbling (BFBC) or circulating (CFBC). Pressurized FBC (PFBC) is an
emerging coal combustion technology.

Answer 126

Fluidized-bed combustion (FBC):

Question 127

solids suspended in space by an upwardly moving gas stream.

Answer 127

Fluidized-bed system

Question 128

the temperature at which the coal ash
becomes fluid and flows in streams

Answer 128

Fluid temperature (ash fluid temperature)

Question 129

airborne bits of unburnable ash that are carried into the atmosphere by stack
gases; coal ash that exits a combustion chamber in the flue gas and is captured by
air pollution control equipment such as electrostatic precipitators, baghouses, and
wet scrubbers

Answer 129

Fly ash

Question 130

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 shap

Answer 130

Formation

Question 131

the accumulation of small, sticky molten particles of coal ash on a boiler
surface

Answer 131

Fouling

Question 132

the part of coal moisture that is removed by
air-drying under standard conditions approximating atmospheric equilibrium.

Answer 132

Free moisture (surface moisture):

Question 133

a measure of the agglomerating tendency of coal heated to
800 ∘C (1470 ∘F) in a crucible. Coals with a high index are referred to as coking
coals; those with a low index are referred to as free-burning coal

Answer 133

Free swelling index:

Question 134

the tendency of coal particles to break down in size during storage, transportation, or handling; quantitatively expressed as the ratio of average particle size
after test to average particle size before test, times 100.

Answer 134

Friability

Question 135

a process for cleaning coal fines in which separation from mineral
matter is achieved by attachment of the coal to air bubbles in a water medium,
allowing the coal to gather in the froth while the mineral matter sinks.

Answer 135

Froth flotation

Question 136

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

Answer 136

Fuse

Question 137

a microscopic coal constituent (maceral) with well-preserved cell structure
and cell cavities empty or occupied by mineral matter

Answer 137

Fusinite

Question 138

a horizontal or a nearly horizontal underground passage, either natural or
artificial

Answer 138

Gallery

Question 139

method of utilizing coal by
burning in place and extracting the released gases, tars, and heat

Answer 139

Gasification, underground (in situ gasification)

Question 140

: gas treatment to remove contaminants such as fly ash, tars, oils,
ammonia, and hydrogen sulfide.

Answer 140

Gas purification:

Question 141

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
which is also called goaf

Answer 141

Gob

Question 142

in the coal industry, the term 5 in. to 3/4 in. means all coal pieces between
5 in. and 3/4 in. at their widest point. Plus 5 in. means coal pieces over 5 in. in size;
11/2 in. to 0 or −11/2 in. means coal pieces 11/2 in. and under

Answer 142

Goal sizes

Question 143

a term indicating the nature of coal as mainly determined by the sulfur content and the amount and type of ash; not recommended for use in coal resource
estimations; definitive statements as to the contents and types of sulfur and ash are preferable—statements indicating high, medium, or low grade are inappropriate
without documentation

Answer 143

Grade

Question 144

an equipment that uses a bed of a separate, closely packed
solids as the separation medium.

Answer 144

Granular bed filters

Question 145

the treatment of coal particles that depends mainly on differences in specific gravity of particles for separation

Answer 145

Gravity separation:

Question 146

a number that indicates the ease of pulverizing a coal in comparison to a reference coal. This index is helpful in estimating mill capacity. The two
most common methods for determining this index are the Hardgrove Grindability Method and Ball Mill Grindability Method. Coals with a low index are more
difficult to pulverize

Answer 146

Grindability index:

Question 147

a course screening or a scalping device that prevents oversized bulk material
from entering a material transfer system; constructed of rails, bars, beams

Answer 147

Grizzly

Question 148

: 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.

Answer 148

Ground control:

Question 149

: a cement applied by spraying to the roof and sides of a mine passage.

Answer 149

Gunite

Question 150

coal with a heat content greater than 10,260 Btu/lb. on a moist ash-free
basis. Includes anthracite, bituminous, and the higher-rank subbituminous coals.

Answer 150

Hard coal:

Question 151

the weight percent of coal retained on a No. 200
sieve after treatment as specified in ASTM Standard Test Method D409

Answer 151

Hardgrove grindability index

Question 152

the horizontal transport of ore, coal, supplies, and waste; the vertical transport of the same is called hoisting.

Answer 152

Haulage

Question 153

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

Answer 153

Haulageway

Question 154

he structure surmounting the shaft which supports the hoist rope pulley,
and often the hoist itself.

Answer 154

Headframe

Question 155

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.

Answer 155

Heading:

Question 156

a term used in both belt and chain conveyor work to designate that
portion of the conveyor used for discharging material.

Answer 156

Head section:

Question 157

the amount of heat obtainable from coal expressed
in British thermal units per pound, joules per kilogram, kilojoules or kilocalories
per kilogram, or calories per gram: to convert Btu/lb to kcal/kg, divide by 1.8. To
convert kcal/kg to Btu/lb, multiply by 1.8.

Answer 157

Heat of combustion, heat value

Question 158

: applied to the rising of the bottom after removal of the coal; a sharp rise in
the floor is called a hogsback

Answer 158

Heaving

Question 159

: a heavy coal tar fraction with distillation range usually 250–300 ∘C
(480–570 ∘F), containing naphthalene and coal tar bases

Answer 159

Heavy oil:

Question 160

the heavy distillate from the pyrolysis of coal at a temperature of about 800 ∘C (1470 ∘F).

Answer 160

High temperature tar

Question 161

three related rank groups of bituminous coal as
defined by the American Society for Testing and Materials which collectively
contain less than 69% fixed carbon on a dry, mineral-matter-free basis; more than
31% volatile matter on a dry, mineral-matter-free basis; and a heat value of more
than 10,500 Btu per pound on a moist, mineral-matter-free basis.

Answer 161

High-volatile bituminous coal

Question 162

the unexcavated face of exposed overburden and coal in a surface mine or
the face or bank on the uphill side of a contour strip mine excavation

Answer 162

Highwall

Question 163

: 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.

Answer 163

Highwall mining

Question 164

a sharp rise in the floor of a seam

Answer 164

Hogsback

Question 165

: a drum on which hoisting rope is wound in the engine house, as the cage or
skip is raised in the hoisting shaft

Answer 165

Hoist

Question 166

: the vertical transport coal or material

Answer 166

Hoisting:

Question 167

a mass of material with a slippery surface in the roof; shaped like a
horse’s back.

Answer 167

Horseback

Question 168

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

Answer 168

Hydraulic

Question 169

hydraulic device for separating suspended solid particles from liquids by centrifugal action. Cyclone action splits the inlet flow, a small part of
which exits via the lower cone, the remainder overflowing the top of the cylindrical section. Particles are separated according to their densities, so that the denser
particles exit via the cone underflow and less dense particles exit with the overflo

Answer 169

Hydrocyclone

Question 170

reaction of carbonaceous material such as coal with hydrogen to
produce methane.

Answer 170

Hydrogasification:

Question 171

chemical reaction in which hydrogen is added to a substance

Answer 171

Hydrogenation

Question 172

coal having 25 wt% or more, but less than 50 wt% ash on the dry basis
(ASTM, 1981; D-2796, p. 344); impure coal having more than 33 weight percent
ash is excluded from resource and reserve estimates unless the coal is cleanable to
less than 33 wt% ash

Answer 172

Impure coal

Question 173

in the direction of the working face

Answer 173

Inby

Question 174

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∘ −18∘), 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.

Answer 174

Incline: a

Question 175

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.

Answer 175

Incompetent

Question 176

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 1/2 to 11/2 miles
apart. Indicated coal is projected to extend as an 1/2 mile wide belt that lies more
than 1/4 mile from the outcrop or points of observation or measurement

Answer 176

Indicated coal resources

Question 177

coal is first gasified to make a synthesis gas. The gas is then
passed over a catalyst to produce methanol or paraffinic hydrocarbons.

Answer 177

Indirect hydrogenation

Question 178

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 1/2 to 6 miles apart.

Answer 178

Inferred coal resources:

Question 179

the term inferred reserves is commonly
used in addition to, or in place of, potential reserves.

Answer 179

Inferred reserves (unproved reserves):

Question 180

the temperature at which coal begins to fuse and become soft

Answer 180

Initial deformation temperature (ash initial deformation temperature)

Question 181

the passage through which fresh air is drawn or forced into a mine or to a
section of a mine.

Answer 181

Intake:

Question 182

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

Answer 182

Intermediate section

Question 183

the roof strata immediately above the coalbed, requiring support
during the excavation of coal.

Answer 183

Immediate roof:

Question 184

a line, on a map, drawn through points of equal thickness of a designated
unit. Synonym for isopachous line; isopachyte

Answer 184

Isopach

Question 185

a percussion drill used for drifting or stopping 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

Answer 185

Jackleg

Question 186

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.

Answer 186

Jackrock:

Question 187

machines that produce stratification of the particles in a bed or particles of differing densities by repeated differential agitation of the bed, the heaviest particles
migrating to the lowest layer. The jigging action may be carried out in air or with
the bed immersed in water or other liquids

Answer 187

Jigs

Question 188

a job breakdown that gives a safe, efficient job procedure.

Answer 188

Job Safety Analysis (JSA):

Question 189

: 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

Answer 189

Kettle bottom

Question 190

the undercut of a coal face

Answer 190

Kerf

Question 191

the electric cap lamp worn for visibility; also, the flame safety lamp used in
coal mines to detect methane gas concentrations and oxygen deficiency.

Answer 191

Lamp

Question 192

the amount of coal obtained from a continuous miner in one mining cycle

Answer 192

Lift

Question 193

a coal tar and coal gas fraction with distillation range between 80 and
210 ∘C (175–410 ∘F) containing mainly benzene with smaller amounts of toluene
and xylene

Answer 193

Light oil

Question 194

; a class of brownish-black, low-rank
coal defined by the American Society for Testing and Materials as having less
than 8300 Btu on a moist, mineral-matter-free basis; in the United States, lignite
is separated into two groups: Lignite A (6300–8300 Btu) and lignite B (<6300
Btu)

Answer 194

Lignite

Question 195

the conversion of coal into nearly mineral-free hydrocarbon liquids or
low-melting solids by a process of direct or indirect hydrogenation at elevated temperatures and pressures and separation of liquid products from residue by either
filtration or distillation or both

Answer 195

Liquefaction

Question 196

a mixture of propane and butane

Answer 196

Liquefied petroleum gas (LPG)

Question 197

coal lithotypes represent the macrostructure of coal and are, in fact,
descriptive of the coal.

Answer 197

Lithotypes

Question 198

to place explosives in a drill hole; also, to transfer broken material into a
haulage device

Answer 198

Load

Question 199

a mining method in which a large rectangular section of coal is
removed in one continuous operation. Equipment is installed along one side of
the section (the longwall face) and the coal is removed in slices 2–4 ft thick. The
excavated area behind the equipment is allowed to cave

Answer 199

Longwall mining

Question 200

: coal fragments larger in size than coal dust.

Answer 200

Loose coal

Question 201

a nitrogen-rich gas with a heat content of 100–200 Btu/ft3 produced
in gasification processes using air as the oxygen source. The air-blown form of
producer gas.

Answer 201

Low-Btu gas

Question 202

up to and including 660 V by federal standards

Answer 202

Low voltage

Question 203

microscopic petrographic units of coal.

Answer 203

Maceral

Question 204

a safety hole constructed in the side of a gangway, tunnel, or slope in which
miner can be safe from passing locomotives and car. This is also called a refuge
hole.

Answer 204

Manhole

Question 205

a carrier of mine personnel, by rail or rubber tire, to and from the work
area

Answer 205

Man trip

Question 206

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% 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 1/2 mile apart. Measured coal is projected to extend as a
1/4-mile wide belt from the outcrop or points of observation or measurement.

Answer 206

Measured coal resources

Question 207

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.

Answer 207

Meridian:

Question 208

coal used in the steelmaking process to manufacture coke; metallurgical coal; an informally recognized name for bituminous coal that is suitable
for making coke by industries that refine, smelt, and work with iron—other uses
are space heating, blacksmithing, smelting of base metals, and power generation;
generally, metallurgical coal has less than 1% sulfur and less than 8% ash on an
as-received basis—most premium metallurgical coal is low- to medium-volatile
bituminous coal

Answer 208

Metallurgical coal

Question 209

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

Answer 209

Methane

Question 210

the microscopic analogs of the coal lithotypes and, hence, represent
a part of the fine microstructure of coal; associations of coal macerals with the
proviso that the associationsshould occur within an arbitrary minimum bandwidth
(50 μ, 50 × 10 mm)

Answer 210

Microlithotypes

Question 211

coal of an intermediate specific gravity and quality

Answer 211

Middlings:

Question 212

: a process for catalytic conversion of 1 mole of carbon monoxide and
3 moles of hydrogen to 1 mole of methane and 1 mole of water

Answer 212

Methanation:

Question 213

a coal tar fraction with a distillation range of
200–270 ∘C (390–520 ∘F), containing mainly naphthalene, phenol, and cresols.

Answer 213

Middle (carbolic or creosote) oil

Question 214

land with new surface characteristics due to the removal of minable
commodities by surface-mining methods and subsequent surface reclamation.

Answer 214

Mined land

Question 215

a coal burning electric-generating plant built near a coal
mine.

Answer 215

Mine mouth electric plant

Question 216

a reaction system in which coal and air or oxygen with steam
are contacted underneath a pool of liquid iron, ash, or salt

Answer 216

Molten bath gasifier

Question 217

a form of surface mining in which
the summit or summit ridge of a mountain is removed in order to permit easier
access to coal seams; after the coal is extracted, the overburden is either put back
onto the ridge to approximate the original contours of the mountain or dumped
elsewhere, often in neighboring valleys; generally associated with coal mining in
the Appalachian Mountain areas

Answer 217

Mountain top removal (mountaintop removal)

Question 218

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. This is also termed adobe, dobie, and sandblast (illegal in coal mining)

Answer 218

Mud cap

Question 219

mining in areas where several seams are recovered from the
same area

Answer 219

Multiple-seam mining

Question 220

a naturally occurring gas with a heat content over 1000 Btu/ft3, consisting mainly of methane but also containing smaller amounts of the C2–C4 hydrocarbons as well as nitrogen, carbon dioxide, and hydrogen sulfide

Answer 220

Natural gas:

Question 221

a device at the end of the trailing cable of a mining machine used for connecting
the trailing cable to the trolley wire and ground.

Answer 221

Nip

Question 222

treatment of a suspension of fine coal particles suspended in
water with a light hydrocarbon oil so that the particles are preferentially collected
by the oil, which separates as a floating pasty agglomerate and can be removed by
skimming. First developed as a method for recovering fine coal particles by Trent
in 1914

Answer 222

Oil agglomeration

Question 223

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

Answer 223

Open end pillaring:

Question 224

a distance nearer to the shaft and hence farther from the working
face, toward the mine entrance, and the opposite of inby

Answer 224

Outby; outbye:

Question 225

enclosed airway which permits one air current to pass over
(under) another without interruption

Answer 225

Overcast (undercast):

Question 226

bituminous coal, the properties of which have been fundamentally
modified as a result of chemisorption of oxygen in the air or oxygen dissolved
in groundwater. The chemisorption is a surface phenomenon rarely detectable by
chemical analysis but usually detectable by petrographic examination. It reduces
the affinity of coal surfaces for oil and seriously impairs coking, caking, and agglutinating properties

Answer 226

Oxidized coal

Question 227

a coal mining block that generally comprises one operating unit

Answer 227

Panel

Question 228

: a switch, in the shape of a bar, used to cut off power at the machine in
case of an emergency.

Answer 228

Panic bar

Question 229

a layer or stratum of non-coal material in a coal bed which does not exceed
the thickness of coal in either the directly underlying or overlying benches.

Answer 229

Parting

Question 230

he 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.

Answer 230

Percentage extraction

Question 231

a drill, usually air powered, that delivers its energy through a
pounding or hammering action.

Answer 231

Percussion drill

Question 232

that which is allowable or permitted. It is most widely applied to mine
equipment and explosives of all kinds that 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.

Answer 232

Permissible:

Question 233

a branch of coal petrology specifically deals with the analysis of the
maceral composition and rank of coal and therefore plays an essential role in predicting coal behavio

Answer 233

Petrography

Question 234

the study of the organic and inorganic constituents of coal and their transformation via metamorphism.

Answer 234

Petrology

Question 235

a processes that employ a number of different operations,
including crushing, sizing, dewatering and clarifying, and drying, which improve
the quality of the fuel by regulating its size and reducing the quantities of ash,
sulfur, and other impurities. In this text, the term coal cleaning is synonymous
with the terms coal preparation, beneficiation, and washing.

Answer 235

Physical coal cleaning:

Question 236

a bridge conveyor.

Answer 236

Piggy-back

Question 237

an area of coal left to support the overlying strata in a mine; sometimes left
permanently to support surface structures

Answer 237

Pillar

Question 238

he 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.

Answer 238

Pillar robbing:

Question 239

: a compression of the walls of a vein or the roof and floor of a coal seam so as
to squeeze out the coal.

Answer 239

Pinch

Question 240

a methane-rich gas with a heat content of 950–1050 Btu/ft3
compressed to 1000 psi

Answer 240

Pipeline gas

Question 241

used in reference to a specifically describable area of open-cut mining. May be
used to refer to only that part of the open-cut mining area from which coal is being
actively removed or may refer to the entire contiguous mined area; also used in
Britain to refer to a mine

Answer 241

Pit

Question 242

a small railroad-type car approximately 6 × 3 in size, used to haul coal, dirt
and rock

Answer 242

Pit Car

Question 243

the inclination of a seam; the rise of a seam; also, the nonvolatile portion of
coal tar.

Answer 243

Pitch:

Question 244

a property of certain coals when heated in the absence of air. For a relative
and a semiquantitative method for determining the relative plastic behavior of coal,
refer to ASTM Standard Test Methods D2639 and D1812, respectively

Answer 244

Plasticity

Question 245

a chronic disease of the lung arising from breathing coal dust.

Answer 245

Pneumoconiosis:

Question 246

a large machine for digging, the digging part of which is a bucket
as the terminal member of an articulated boom. Power to the bucket is supplied
through hydraulic cylinders or cables.

Answer 246

Power shovel

Question 247

a measure of the maximum random error or deviation of a single observation. It may be expressed as the standard error or a multiple thereof, depending
on the probability level desired

Answer 247

Precision

Question 248

the heating of coal in a preheating column to
180–300 ∘C (355–570 ∘F) to dry off all the moisture and leave a hot, dry fluid
coal that can be charged by gravity or pipeline

Answer 248

Preheating (coke making):

Question 249

mild oxidation of coal to eliminate caking (agglomeration) tendencies.

Answer 249

Pretreatment

Question 250

a package or cartridge of explosive which is designed specifically
to transmit detonation to other explosives and which does not contain a detonator.

Answer 250

Primer (booster)

Question 251

: mainly carbon monoxide with smaller amounts of hydrogen, methane,
and variable nitrogen, obtained from partial combustion of coal or coke in air or
oxygen, having a heat content of 110–160 Btu/ft3 (air combustion) or 400–500
Btu/ft3 (oxygen combustion)

Answer 251

Producer gas

Question 252

the determination by prescribed methods of moisture, volatile
matter, fixed carbon (by difference), and ash; unless specified, proximate analyses do not include determinations of sulfur or phosphorous or any determinations other
than those named; proximate analyses are reported by percent and on as-received,
moisture-free, and moisture- and ash-free bases. Pulverized coal combustion refers
to any combustion process that uses very finely ground (pulverized) coal in the
process

Answer 252

Proximate analysis:

Question 253

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

Answer 253

Raise:

Question 254

a secondary or tertiary inclined opening, driven to connect levels, usually
driven in a downward direction, and used for haulage.

Answer 254

Ramp: a

Question 255

run-of-mine coal that has been treated by the removal of tramp material,
screening, or crushing.

Answer 255

Raw coal:

Question 256

: the process of reconverting mined land to its former or other productive
uses.

Answer 256

Reclamation

Question 257

unmined coal deposits that can be removed by current
technology, taking into account economic, legal, political and social variables.

Answer 257

Recoverable reserves (coal)

Question 258

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 coal ash

Answer 258

Red dog

Question 259

: the ratio between the feed top size and the product top size; the
ratio between the feed and product sizes

Answer 259

Reduction ratio

Question 260

the measure of agreement between test results carried out by more
than one person with more than one instrument in more than one laboratory.

Answer 260

Reproducibility

Question 261

closeness of agreement between test results carried out by one
person with one instrument in one laboratory

Answer 261

Repeatability

Question 262

that portion of the identified coal 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 coal resource designated as the reserve base

Answer 262

that portion of the identified coal 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 coal resource designated as the reserve base

Question 263

a method of permanent roof support in which steel rods are grouted
with resin.

Answer 263

Resin bolting

Question 264

dust particles 5 𝜇 or less in size

Answer 264

Respirable dust

Question 265

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

Answer 265

Respirable dust sample

Question 266

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.

Answer 266

Retreat mining

Question 267

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.

Answer 267

Return idler

Question 268

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.

Answer 268

Rib: t

Question 269

a thin seam of coal overlying a thicker one.

Answer 269

Rider:

Question 270

a coal extraction machine that works by tearing the coal from the face.

Answer 270

Ripper

Question 271

to extract pillars of coal previously left for support

Answer 271

Rob:

Question 272

that part of a mine from which the pillars have been removed

Answer 272

Robbed out area

Question 273

) 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.

Answer 273

Roll: (

Question 274

a framework, safety canopy, or similar protection for the operator
when equipment overturns

Answer 274

Roll protection

Question 275

: 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 ft 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.

Answer 275

Roof bolt

Question 276

a coal mine cave-in especially in permanent areas such as entries.

Answer 276

Roof fall

Question 277

a screw- or pump-type hydraulic extension post made of steel and used
as temporary roof support.

Answer 277

Roof jack

Question 278

the sinking, bending, or curving of the roof, especially in the middle, from
weight or pressure.

Answer 278

Roof sag

Question 279

unbalanced internal forces in the roof or sides, created when coal is
extracted

Answer 279

Roof stress

Question 280

: 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

Answer 280

Roof support:

Question 281

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

Answer 281

Roof trusses

Question 282

a mining method in which a designated area is divided
into regular-shaped coal pillars through the parallel development of entries and
cross-cuts. After the area is so developed, the remaining pillars are mined by slicing them into smaller pillars

Answer 282

Room-and-pillar mining:

Question 283

the short passage from the entry into a room

Answer 283

Room neck

Question 284

: planned pattern of drill holes fired in sequence in tunneling, shaft sinking,
or stopping. First the cut holes are fired, followed by relief, lifter, and rib holes.

Answer 284

Round

Question 285

he total area (top, bottom, and sides) of an airway

Answer 285

Rubbing surface

Question 286

: raw coal as it leaves the mine prior to any type of crushing or
preparation

Answer 286

Run-of-mine coal:

Question 287

: 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.

Answer 287

Safety fuse

Question 288

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

Answer 288

Safety lamp

Question 289

a large unmined area left between a mining section and mine openings
designated for long-term use. It is laid out to absorb the abutment loads created by the mining activity and to prevent any adverse effects on the openings designated
for long-term use.

Answer 289

Safety pillar

Question 290

any of several forms of chemical/physical devices that remove sulfur
compounds formed during coal combustion. These devices, technically known 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
disposa

Answer 290

Scrubbers

Question 291

the object of selective mining is to obtain a relatively high-grade
mine product; this usually entails the use of a much more expensive stopping system and high exploration and development costs in searching for and developing
the separate bunches, stringers, lenses, and bands of ore.

Answer 291

Selective mining

Question 292

a self-contained supply of oxygen used during
rescue work from coal mine fires and explosions; same as SCSR (self-contained
self-rescuer)

Answer 292

Self-contained breathing apparatus:

Question 293

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 min and 1 h

Answer 293

Self-rescuer:

Question 294

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.

Answer 294

Severance

Question 295

a deep vertical passage used to enter the mine below; a shaft has to be sunk
or dug out until the vein of coal is reached. When a coal vein or layer was found,
then the digging began in a mainly horizontal direction to follow the vein

Answer 295

Shaft

Question 296

an underground mine in which the main entry or access is by means of
a vertical shaft

Answer 296

Shaft mine

Question 297

a large pulley used to guide a cable. Sheaves at the mine were placed at the
highest point of the tipple called the headframe. These sheaves guided the cables
that raised and lowered the cages.

Answer 297

Sheave

Question 298

a mining method with a panel layout similar to longwall mining
but at a panel width reduced by approximately 50%. It uses continuous-mining
equipment for coal cutting and haulage and a specially designed hydraulic roof
support.

Answer 298

Shortwall mining

Question 299

an excavating or coal-loading machine that uses a bucket mounted on and
operated by means of a handle or dipper stick that moves longitudinally on gears
and is lifted or lowered by cable. The entire machine is mounted on crawlers for
mobility, and the upper structure is mounted on rollers and rail for swing or turn

Answer 299

Shovel:

Question 300

the slope of the sides of a canal, dam, or embankment. It is customary
to name the horizontal distance first as 1.5–1.0 or frequently 11/2:1, meaning a
horizontal distance of 1.5–1 ft vertical.

Answer 300

Side slope

Question 301

the process by which a shaft is driven

Answer 301

Sinking:

Question 302

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

Answer 302

Skid

Question 303

: a car being hoisted from a slope or shaft

Answer 303

Skip

Question 304

a triggering mechanism that causes mine cars (pit cars) to dump its load
of coal or rock to a designated area at the mine.

Answer 304

Skipjack

Question 305

small coal; the finest-sized soft coal, usually less than one inch in diameter

Answer 305

Slack

Question 306

the nonmetallic product resulting from the interaction of flux and impurities in
the smelting and refining of metals

Answer 306

Slag

Question 307

the primary combustion chamber for a cyclone-fired boiler. Ash from
the coal melts in the cyclone and is removed as a slag

Answer 307

Slag cyclone:

Question 308

: the accumulation of coal ash on the wall tubes of a coal-fired boiler furnace,
forming a solid layer of ash residue and interfering with heat transfer.

Answer 308

Slagging:

Question 309

a significant amount of dirt and rock excavated from the earth below that
is dumped into a pile.

Answer 309

Slag pile

Question 310

a smooth, striated, polished surface produced on rock by friction

Answer 310

Slickenside

Question 311

a long, narrow refractory chamber charged with coal heated in the absence
of air by adjacent heating flues. Ovens are arranged in batteries with heating flues
between each pair, like books on a shelf. Typical ovens are 457 mm wide, 12–15 m
long, and 4–6 m high.

Answer 311

Slot oven

Question 312

the slow crumbling and falling away of material from roof, rib, and face

Answer 312

Sloughing:

Question 313

a mixture of pulverized insoluble material and water.

Answer 313

Slurry

Question 314

a pipeline that can transport a coal-water mixture for long distances.

Answer 314

Slurry pipeline

Question 315

knocking on a roof to see whether it is sound and safe to work under

Answer 315

Sounding

Question 316

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.

Answer 316

Spad:

Question 317

the horizontal distance between the side supports or solid abutments along
sides of a roadway

Answer 317

Span: t

Question 318

bubbling a gas into the bottom of a pool of liquid

Answer 318

Sparging

Question 319

US Bureau of Mines term for durain with some vitrain and clarain and
small amount of fusain.

Answer 319

Splint coal

Question 320

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

Answer 320

Split

Question 321

coal that is disturbed by layers of other geologic material, usually layers
of shale

Answer 321

Split coal

Question 322

the overburden or non-coal material removed in gaining access to the coal or
mineral material in surface mining

Answer 322

Spoil:

Question 323

the self-ignition of coal through oxidation under
very specific conditions. Different types of coal vary in their tendency toward
self-ignition

Answer 323

Spontaneous combustion

Question 324

a person whose occupation is to apply braking to the mine cars below by
means of placing wood blocks or wedges underneath the wheels to prevent them
from rolling down slight grades

Answer 324

Spragger:

Question 325

the volume of coal (27,878,400 ft3; 789,428.38 m3; 1,032,
533.33 yd3) that covers 1 square mile to a thickness of 1 foot; the weight of coal
varies according to the rank.

Answer 325

Square mile-foot:

Question 326

the settling, without breaking, of the roof and the gradual upheaval of the
floor of a mine due to the weight of the overlying strata.

Answer 326

Squeeze

Question 327

the product gas evolved during complete combustion of a fuel.

Answer 327

Stack gas

Question 328

a chain conveyor of a design similar to the face conveyor. It provides
a connection between the face conveyor and the section conveyor belt.

Answer 328

Stage loader

Question 329

said of deposits and coal seams with a dip of from 0.7 to 1 rad
(40–60∘).

Answer 329

Steeply inclined

Question 330

the noncombustible material used on top or in front of a charge or explosive.

Answer 330

Stemming

Question 331

a mine gas containing a high proportion of hydrogen sulfide

Answer 331

Stinkdamp

Question 332

the combustion of coal on a grate, which may be stationary or moving

Answer 332

Stoker firing

Question 333

refers to a procedure of mining that entails the complete removal of all
material from over the product to be mined in a series of rows or strips; this is also
referred to as open cut, open pit, or surface mine

Answer 333

Strip mine:

Question 334

the removal of earth or non-ore rock materials as required to gain access
to the ore or mineral materials wanted. The process of removing overburden or
waste material in a surface mining operation

Answer 334

Stripping

Question 335

the unit amount of spoil or waste (overburden) that must be removed
to gain access to a similar unit amount of ore or mineral material

Answer 335

Stripping ratio

Question 336

a glossy-black-weathering and nonagglomerating coal that is
lower in fixed carbon than bituminous coal, with more volatile matter and oxygen;
a rank class of nonagglomerating coals having a heat value content of more than
8300 Btu’s and less than 11,500 Btu’s on a moist, mineral-matter-free basis—this
class of coal is divisible on the basis of increasing heat value into the subbituminous C, B, and A coal groups.

Answer 336

Subbituminous coal

Question 337

the bottom of a shaft, or any other place in a mine, that is used as a collecting
point for drainage water.

Answer 337

Sump:

Question 338

to force the cutter bar of a machine into or under the coal. This is also
called a sumping cut or sumping in

Answer 338

Sumping

Question 339

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

Answer 339

Support:

Question 340

a mine in which the coal lies near the surface and can be extracted by
removing the covering layers of rock and soil.

Answer 340

Surface mine

Question 341

: gas from which acid (sour) gases such as H2 S and CO2 have been
removed

Answer 341

Sweetened gas

Question 342

synthetic crude oil produced by pyrolysis or hydrogenation of coal or coal
extracts

Answer 342

Syncrude

Question 343

approximately 2:1 molar mixture of hydrogen and carbon
monoxide with varying amounts of carbon dioxide

Answer 343

Synthesis gas (syngas)

Question 344

pipeline-quality gas that is interchangeable with
natural gas (mainly methane).

Answer 344

Synthetic (substitute) natural gas

Question 345

residual gas leaving a process; gas produced in a refinery and not usually
required for further processing.

Answer 345

Tail gas

Question 346

: 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.

Answer 346

Tailgate

Question 347

: 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.

Answer 347

Tailpiece

Question 348

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.

Answer 348

Tail section

Question 349

an old time train locomotive consisting of ten wheels, also referred to
as a 4–6–0, four small wheels up front near the pilot (cow catcher) and six larger
wheels under the middle of the loco and zero wheels at the rear or under the cab
where the engineer sa

Answer 349

Ten-Wheeler

Question 350

lateral or panel openings (e.g., ramp, crosscut).

Answer 350

Tertiary

Question 351

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

Answer 351

Through-steel

Question 352

a collective term for underground wooden supports.

Answer 352

Timber:

Question 353

the setting of timber supports in mine workings or shafts for protection
against falls from roof, face, or rib

Answer 353

Timbering

Question 354

originally the place where the mine cars were tipped and emptied of their
coal; still used in that sense, although now more generally applied to the surface
structures of a mine, including the preparation plant and loading tracks. The tracks,
trestles, screens, and so on at the entrance to a colliery where coal is screened and
loaded

Answer 354

Tipple

Question 355

a short or net ton is equal to 2000 lb; a long or British ton is 2240 lb; a metric
ton is approximately 2205 lb

Answer 355

Ton

Question 356

: the smallest sieve size upon which is retained a total of less than 5% w/w
of a total sample.

Answer 356

Top size

Question 357

a wrench that indicates, as on a dial, the amount of torque (in units
of foot-pounds) exerted in tightening a roof bolt.

Answer 357

Torque wrench:

Question 358

: a gaseous mixture of coal gas and carbureted water gas manufactured from
coal with a heat content of 600 Btu/ft3.

Answer 358

Town gas

Question 359

acid spoil with pH below 4.0; also spoil having amounts of minerals,
such as aluminum, manganese, and iron, that adversely affect plant growth.

Answer 359

Toxic spoil:

Question 360

person whose duty it was to lay railroad track to selected areas wherein
miners could conveniently load the pit cars with coal

Answer 360

Trackman:

Question 361

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.

Answer 361

Tram

Question 362

: a vertical or inclined connection between two or more levels and used as
an ore pass

Answer 362

Transfer:

Question 363

location in the materials handling system, either haulage or hoisting,
where bulk material is transferred between conveyances.

Answer 363

Transfer point

Question 364

a person, usually of a young age, who opened and closed doors down below
in the mine for drivers. The doors down below were used to guide the downcast or
airflow to desired areas of the mine.

Answer 364

Trapper

Question 365

an apparatus in which coal is lifted vertically in a revolving
cylinder and dropped through an axially flowing stream of oxygen and steam.

Answer 365

Tumbling-bed gasifier

Question 366

partial gasification or pyrolysis in a first step followed by
complete gasification of the resultant char in a second step

Answer 366

partial gasification or pyrolysis in a first step followed by
complete gasification of the resultant char in a second step

Question 367

: a train of mine cars.

Answer 367

Trip

Question 368

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

Answer 368

Troughing idlers:

Question 369

the analytical percentage by weight of coal carbon, hydrogen,
nitrogen, sulfur, oxygen, and ash; the determination by prescribed methods
of the ash, carbon, hydrogen, nitrogen, oxygen (by difference), and sulfur
contents—quantities of each analyzed substance are reported by percentage for
the following conditions: as-received, dried at 105 ∘C (221 ∘F), and moisture-and
ash-free.

Answer 369

Ultimate analysis

Question 370

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 use

Answer 370

Undercut

Question 371

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.

Answer 371

Underground mine

Question 372

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.

Answer 372

Underground station:

Question 373

reserves that are yet to be discovered; the term and the associated speculative data are often used in reserve estimation.

Answer 373

Undiscovered reserves

Question 374

a long train of between 60 and 150 or more hopper cars, carrying only
coal between a single mine and destination; a railway train designated to achieve
economies of scale by transporting a single commodity (such as coal), loading
fully and operating nonstop.

Answer 374

Unit train

Question 375

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

Answer 375

Universal coal cutter:

Question 376

a shaft through which air leaves the mine

Answer 376

Upcast shaft:

Question 377

the act or process of valuing or of estimating the value or worth; appraisal.

Answer 377

Valuation

Question 378

the rate of airflow in lineal feet per minute.

Answer 378

Velocity

Question 379

a macroscopic coal constituent (lithotype) that appear as brilliant black
bands of uniform appearance and greater than 10−2 mm thick.

Answer 379

Vitrain:

Question 380

a microscopic coal constituent (maceral) that appears translucent by transmitted light and gray in reflected light; termed anthraxylon when viewed by transmitted light

Answer 380

Vitrinite:

Question 381

a general term for pore space or other openings in rock. In addition to pore
space, the term includes vesicles, solution cavities, or any openings either primary
or secondary

Answer 381

Void

Question 382

a procedure used in a laboratory before preparation plant
design to determine the cleaning processes to be employed and used during
normal operation to evaluate the performance of the cleaning equipment and the
amenability of the raw coal feed to the cleaning processes chosen.

Answer 382

Washability analysis:

Question 383

the sudden erosion of soft soil or other support surfaces by a gush of water;
if a washout occurs in a crater-like formation it is a sinkhole

Answer 383

Washout

Question 384

a mixture of carbon monoxide and hydrogen formed
by the action of air and then steam on hot coal or coke and enriched with hydrocarbon gases from the pyrolysis of oils

Answer 384

Water (carbureted blue) gas:

Question 385

: an instrument that measures differential pressures
in inches of water.

Answer 385

Water gauge (standard U-tube)

Question 386

a piece of wood tapering to a thin edge and used for tightening in conventional timbering

Answer 386

Wedge:

Question 387

fracturing and lowering of the roof strata at the face as a result of mining
operations, as in taking weight.

Answer 387

Weight

Question 388

: 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% (0.001) may be fatal in 10 min.

Answer 388

White damp

Question 389

the thickness of a lode measured at right angles to the dip

Answer 389

Width

Question 390

the excavation, loading, and removal of coal or ore from the ground; winning follows development.

Answer 390

Winning

Question 391

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 level

Answer 391

Winze

Question 392

: 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,
cable-laid 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, non-spinning rope, regular lay,
reverse-laid rope, rheostat rope, right lay, right twist, running rope, special flexible
hoisting rope, standing rope, towing hawser, transmission rope

Answer 392

Wire rope

Question 393

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.

Answer 393

Working

Question 394

any place in a mine where material is extracted during a mining cycle

Answer 394

Working face:

Question 395

from the outby side of the last open crosscut to the face

Answer 395

Working place:

Question 396

the entire system of openings in a mine for the purpose of exploitation

Answer 396

Workings

Question 397

from the faces to the point where coal is loaded onto belts or rail
cars to begin its trip to the outside.

Answer 397

Working section