Elastic recovery from strain. AGI
Waves that travel only on a free surface where the solid elastic materials
transmitting them are bounded by air or water. Leet, 2
In explosion-formed crater nomenclature, the remote zone that undergoes no
measurable permanent deformation. Min. Miner. Eng., 2
A massive, amorphous, dark-brown metamorphic hydrocarbon ranging from soft
and elastic to hard and brittle; melts in a candle flame without
decrepitation; conchoidal fracture. Also called liverite.
See also:coorongite; wurtzilite. Syn:elastic bitumen;
elastic mineral pitch; mineral caoutchouc.
a. See:red schorl; rubellite; ilvaite.
b. A trigonal mineral, 3[Na(Li,Al)3 Al6 (OH,F)4 (BO
3 )3 Si6 O18 ] ; tourmaline group; occurs in
triangular and hexagonal prisms; varicolored; commonly zoned, pyroelectric
and piezoelectric; in granites and granite pegmatites; and used as a
gemstone (pink rubellite, blue indicolite, green verdolite, colorless
achroite, zoned pink-white-green watermelon tourmaline).
A trough-type roller or wheel conveyor consisting of two parallel rows of
rolls or wheels set at a 90 degrees included angle, with one row providing
a sloped carrying surface and the other acting as a guard.
See also:roller conveyor; troughed roller conveyor; wheel conveyor.
A trade name in El Dorado County, California, for a blue quartz that may
be cut as a gemstone.
A type of tripod drill operated by compressed air supplied by a portable
motor-driven compressor that accompanies the drill. Fay
A measure of the ease with which a conduction current can be caused to
flow through a material under the influence of an applied electric field.
It is the reciprocal of resistivity and is measured in mhos per meter.
AGI
Helmholtz layer. Zone that surrounds a particle in aqueous suspension or
other electrolyte. Transition zone between the monomolecular zone of shear
immediately coupled ionically to the discontinuity lattice at the
particle's surface and the normal aqueous phase that exists from 50 to
5,000 Aa and beyond. This zone of change contains a superconcentration of
ions drawn from the normal population of the liquid phase.
See also:zeta potential
An engineer in charge of all electrical plant and associated labor at a
mine or colliery. He or she has an assistant in charge of all the
underground electrical equipment, operations, and labor. The electrical
engineer is under the authority of the colliery manager. Nelson
A geophysical prospecting method that depends on the electrical or
electrochemical properties of rocks. The resistivity,
spontaneous-polarization, induced-polarization, and
inductive-electromagnetic methods are the principal electrical methods.
AGI
A plan, drawn to the same scale as the working plan, that shows the
position of all electrical apparatus installed underground except signals
and telephones. Nelson
The removal of suspended particles from gases by the aid of electrical
discharges, using alternating or direct current. Alternating current
agglomerates the suspended particles into larger aggregates, causing rapid
settling, esp. if the gases are quiescent. Direct current is used when
large volumes of rapidly moving gas, such as occur in smelter flues, are
treated. The suspended particles within a strong electric field of
constant polarity become charged and are then attracted to a plate
(electrode) of opposite charge. Fay
Prospecting that makes use of three fundamental properties of rocks. One
is the resistivity, or inverse conductivity. This governs the amount of
current that passes through the rock when a specified potential difference
is applied. Another is the electrochemical activity with respect to
electrolytes in the ground. This is the basis of the self-potential
method. The third is the dielectric constant. This gives information on
the capacity of a rock material to store electric charge, and it must be
taken into consideration when high-frequency alternating currents are
introduced into the earth, as in inductive prospecting techniques.
Electrical methods are more frequently used in searching for metals and
minerals than in exploring for petroleum, mainly because most of them have
proved effective only for shallow explorations. Dobrin
Protection is provided by fuses or other suitable automatic
circuit-interrupting devices for preventing damage to circuits, equipment,
and personnel by abnormal conditions, such as overcurrent, high or low
voltage, and single phasing.
A rock fracturing technique, applied to secondary fragmentation in
quarries, that is characterized by an almost instantaneous action and is
accompanied by a mechanical weakening of the dielectric and a lowering of
the resistance of the puncture path. If, after puncturing, a
high-frequency current continues to pass between the contacts, the action
of the conduction current and electric field will rapidly heat the rock,
leading to thermal puncture, in which the dielectric is transformed into a
good conductor along the puncture path. Further intensive heating will
give rise to thermal stresses sufficient to fracture the rock.
Min. Miner. Eng., 1
electrical resistance inclinometer
An instrument to indicate when a long hole in a coal seam is deviating
into the roof or floor. It may be used in underground gasification and
pulsed-infusion shotfiring. It uses, among other things, a pellet of
mercury to indicate the gradient by its position along a tube.
Nelson
electrical resistance strain gage
An appliance for measuring strain that may be employed in roof-control
research. It makes use of the change in electrical resistance of a thin
wire when stretched under the influence of strata strain.
Syn:resistance strain gage
mechanical extensometer. Nelson
A rock-fracturing technique in which electrical energy is used directly in
fracturing the rock, either by heating it in a variable electric or
electromagnetic field set up in the rock by a high-frequency electric
current, or by the direct puncturing of the rock by an electric current.
Min. Miner. Eng., 1
Slate principally of the mica variety. It should have high mechanical and
dielectric strength, be readily machinable, and have low porosity.
USBM, 7