Coal worked from breasts or bords to the rise of a counter gangway.
Fay
Arrangement in which ore, or pulp, proceeds in one direction and is
progressively stripped of part of its contained mineral, while the
enriched fraction thus produced moves in the opposite direction, the
results being central feed, with discharge of high-grade concentrate at
one end of the process and low-grade or barren tailing at the other.
Pryor, 3
Braking accomplished by reversing the motor connections, at the same time
inserting appropriate resistance in the rotor circuit to adjust the
negative torque to the desired value. With this method, complete control
of deceleration is obtained, even to a dead stop. Its greatest
disadvantage is that it is expensive in current consumption. It is
unsuitable for winders sited at depth, owing to the heat given out.
Spalding
The clarification of washery water and the concentration of tailings by
the use of several thickeners in series. The water flows in the opposite
direction from the solids. The final products are slurry that is removed
as fluid mud and clear water that is reused in the circuit. May be broader
than just thickener. Syn:cascade upgrading
A means of maintaining the chemical potential at a uniform level during a
reaction. Newton, 1; Newton, 2
In a heat exchanger, where the fluid absorbing heat and the fluid losing
heat are so directed that lower and higher temperature of the one is
adjacent to the lower and higher temperature of the other, respectively.
Ordinarily, the one fluid is flowing in the opposite direction from the
other, hence the term. Strock, 2
See:counterboring
A gangway driven obliquely across the workings to a higher level, or a
gangway driven between two lifts and sending its coal down to the gangway
below through a chute. Fay
Mid. An underground heading driven parallel to another, and used as the
return air course.
See:cast
In a twist drill, the tapered and relieved cutting portion situated
between the pilot drill and the body. Osborne
A cross vein running at approx. right angles to the main orebody.
Slate, size 20 in by 10 in (50.8 cm by 25.4 cm); a duchess is 24 in by 12
in (61.0 cm by 30.5 cm), and a princess is 24 in by 14 in (61.0 cm by 35.6
cm). Terms descriptive of slate trimmed for roofing. Pryor, 3
Approximate method of analysis, where particles of value and gangue are
similar in shape and size, and their proportions can be assessed by
inspection, probably under a low-powered microscope. Pryor, 3
Arkansas. A small mine supplying coal for local use only.
The rock enclosing or traversed by a mineral deposit. Originally a miners'
term, it is somewhat less specific than host rock. Syn:wall rock
AGI
A combination of the panel and room-and-pillar method of mining.
See also:room-and-pillar
A type of surface wave that is continuously generated by another wave that
has the same phase velocity. Syn:C-wave
Genetically related paired sedimentary laminae, generally occurring in
repeating series, as varves, but applied to laminated nonglacial shales,
evaporites, and other sediments as well. AGI
a. A device for connecting tubs or mine cars to form a set or journey.
See also:automatic clip; clip; shackle. Nelson
b. A connector for drill rods, casing, or pipe with identical box or pin
threads at either end. Long
In coal mining, steel plate on which tubs are turned from one set of rails
to another. Pryor, 3