A safety lamp invented by Sir Humphrey Davy in 1815 for the protection of
coal miners. Its safety feature consisted of a fine-wire gauze enclosing
the flame to keep it from coming in contact with mine gas.
See also:flame safety lamp; safety lamp. Fay
A hexagonal mineral, (Na,Ca,K)8 Al6 Si6 O24
(Cl,SO4 ,CO3 )2 ; cancrinite group; vitreous to
pearly. Also spelled davina.
An orthorhombic mineral, NaAl(CO3 )(OH)2 ; white; forms thin
incrustations of radiating bladed crystals.
a. A term used to signify the surface; e.g., driven to day, meaning to
daylight, therefore to the surface.
b. Wales. The surface of the ground over a mine.
c. In mining, generally a period of 8 h for work on the three-shift
system, or 24 h if referring to the output or to machinery. CTD
See:powder chest
The topmost stratum of coal; so called from its being nearest to daylight.
Standard, 2
a. When an underground mine working meets the surface it is said to
daylight. Long
b. The maximum clear distance between the pressing surfaces of a hydraulic
press with the surfaces in their usable open position. Where a bolster is
supplied, it shall be considered the pressing surface. ASM, 1
A continuous method of making ingots or billets for sheet or extrusion by
pouring the metal into a short mold. The base of the mold is a platform
that is gradually lowered while the metal solidifies, the frozen shell of
metal acting as a retainer for the liquid metal below the wall of the
mold. The ingot is usually cooled by the impingement of water directly on
the mold or on the walls of the solid metal as it is lowered. The length
of the ingot is limited by the depth to which the platform can be lowered;
therefore, it is often called semicontinuous casting. ASM, 1
In froth flotation, treatment of one or more species of mineral particles
to reduce their tendency to float.
a. Said of a mine, vein, or piece of ground that is unproductive.
b. Said of coal that is under no pressure, does not warp and burst, and
makes no sound. CF:alive
c. In economic geology, said of an economically valueless area, in
contrast to a quick area or ore; barren ground. AGI
a. Stagnant air. BS, 8
b. The air of a mine when it contains carbonic acid gas (blackdamp), or
when ventilation is sluggish. Fay
In flotation, the range through which an input can be varied without
initiating response. Fuerstenau
Unproductive stratum or vein as opposed to bearing or quick bed.
Syn:dead vein
a. The state of a basic refractory material resulting from a heat
treatment that yields a product resistant to atmospheric hydration or
recombination with carbon dioxide. ASTM
b. Completely calcined. AISI
A refractory product, CaO.MgO, produced by calcination of dolomite or
dolomitic limestone. AGI
A sintered product consisting mainly of magnesia in the form of dense,
weather-stable refractory granules.
Calcination of limestone, dolomite, or magnesite to the point where
associated clay vitrifies and reduces slaking quality. Pryor, 1
See:chalky chert
a. An entry, gangway, level, or other mine passage extending beyond the
mine workings into solid coal or ore; a stub. Syn:stub entry
b. Underground passageway either blocked or not holed through.
Pryor, 3
c. The unworked end of a drift or working. Hess
d. An unventilated underground mine passage extending some distance beyond
other mine workings into solid rock. Long
e. A term used in coal mining for the termination of all electric wiring
(except cables to equipment) outby the last crosscut where ample
ventilation will reduce the possibility of an electric arc causing an
explosion. Kentucky
f. The end of a drilling line or cable made fast to some stationary part
of the drill rig or to a deadman. Long
a. Rock in a mine that, although producing no ore, requires removal in
order to get to productive ground.
b. In mining subsidence, ground that has settled and no further movement
is expected. Nelson
c. Portions of ore deposit too low in value to repay exploitation.
CF:barren ground
a. To return to the commencement of a cut without excavating; usually for
the commencement of a new cut after completion of its predecessor.
Austin
b. An extra length given to a cast object, as a cannon, to put pressure on
the molten metal below so that dross and gases may rise into it; a sullage
piece; a sinking head. Standard, 2
c. That part of a casting filling up the ingate; a sprue.
Standard, 2
d. Can. Logs forced into the bottom of a waterway during timber drives.
Hoffman