An isometric mineral, MnO ; periclase group; emerald-green; forms
octahedra that blacken on exposure to air.
An orthorhombic mineral, MnTa2 O6 ; dimorphous with
manganotapiolite; forms series with manganocolumbite and with
ferrotantalite.
A hexagonal mineral, (Mn,Fe)8 Si6 O15 (OH,Cl) (sub
10) ; dimorphous with brokenhillite; forms a series with ferropyrosmalite.
A tropical or subtropical low-energy coast with a shore zone overgrown by
mangrove vegetation. Such coasts are common in Indonesia, Papua New
Guinea, and other tropical regions. The marine coast of southern Florida
is the only significant U.S. example. AGI
a. A safety hole. Hudson
b. Cubicles cut into the solid strata or built into the gob pile along
haulageways in which miners can be safe from passing locomotives and cars.
Also called refuge hole. BCI
c. A refuge hole constructed in the side of a gangway, tunnel, or slope.
Fay
d. A small and generally very short passage used only for the ingress and
egress of the miners. Fay
e. A hole in cylindrical boilers through which a worker can get into the
boiler to examine and repair it. Fay
f. A small passage connecting a level with a stope, or with the level next
above. Webster 2nd
A movable cast-iron plate fitting a cast-iron frame bedded on a rebated
concrete slab or kerb over a manhole. Covers over foul drains are formed
to prevent escape of foul air. Hammond
Broadly, rope or cordage formed from twisted fibers obtained from abaca,
agave, or hemp plants. Long
In mineral processing, a quantity or condition that is varied as a
function of the actuating signal so as to change the value of the
controlled variable. Fuerstenau
a. A machine for moving and turning over hot billets or blooms of iron or
steel in the process of rolling. Standard, 2
b. A mechanical device used for safe handling of radioactive materials.
Frequently, it is remotely controlled from behind a protective shield.
Lyman
A coal face mined by remotely controlled equipment that eliminates the
need for workers in dangerous places. Encyclopaedia Britannica
Longwall coal faces equipped for the automatic starting, stopping, and
steering of power-loading machines as well as the manipulation of electric
trailing cables, including air and water hoses; controlled automatic
advancing of face conveyors as well as advancing and setting of roof
supports. Each and all operations are correctly phased and accomplished
from a remote point. With the advent of electronics and automation
techniques, the prospects of manless coal mining are very promising.
Nelson
A longwall face on which the coal is cut and brought out to the gate road
mechanically, without the aid of miners on the face. The face is
unsupported. In general, the coal seam is thin but of high grade, and some
type of rapid plow is employed. See also:coal-sensing probe;
ram scraper. Nelson
An air lock through which workers pass to a working chamber that is under
air pressure. Hammond
Corn.; Derb. An obsolete term for a mechanical lift for lowering and
raising miners in a shaft by means of a reciprocating vertical rod of
heavy timber with platforms at intervals, or of two such rods moving in
opposite directions. In the former case, stationary platforms are placed
in the shaft, so that the miner in descending, for instance, can step from
the moving platform at the end of the downstroke and step back upon the
next platform below at the beginning of the next downstroke. When two rods
are employed, the miner steps from the platform on one rod to that on the
other. Syn:man engine; movable ladder. Fay
Diamond produced synthetically. Also called MM diamond.
See also:diamond; synthetic diamond. Long
Contact method of catalyzing SO2 to SO3 in two stages, using
first iron oxide and second platinized asbestos as catalysts.
Pryor, 3
An empirical formula for the value of the coefficient, C, in the Chezy
formula, the factors of which are the hydraulic radius and a coefficient
of roughness; a simplification of the Kutter formula. Seelye, 1
Staff. A small pillar of coal left in a critical spot; also, a principal
support in thick coal workings. Fay
a. Any instrument that measures gaseous pressure. Nelson
b. Measures pressure or a pressure difference by balancing the applied
pressure against the hydrostatic head of a column of liquid of known
density. In practice, most manometers measure a pressure difference, so
that if an absolute pressure is to be measured, it is essential to have
access to an accurate barometer to determine the atmospheric pressure.
Roberts, 1
c. An instrument designed to give a continuous record of the pressure of
an explosion at the point where the instrument is located.
See also:micromanometer; piezometer; two-liquid differential manometer;
U-tube manometer; vernier-reading manometer; water gage.
Rice, 2; Roberts, 1
Many manometers require calibration, and this may be carried out by the
(1) static method in which simultaneous readings of the manometer under
test and the primary standard are taken when one limb of the manometer and
the standard are connected to a variable pressure source, the other limbs
being connected to a source of constant pressure, or (2) the dynamic
method in which the difference in pressure obtained between a low-speed
atmospheric wind-tunnel hole (static pressure) and the atmospheric static
pressure is used to carry out the calibration. One limb of the manometer
and the low-pressure side of the Chattock-Fry are connected to the
tunnel-wall hole (reference variable pressure), while the other limb of
the manometer is connected to the atmospheric outlet of the Chattock-Fry.
Roberts, 1
a. The ratio of the actual head developed to the velocity pressure of air
moving at the fan-tip speed, equal to one-half the theoretical head of a
radial-tip fan. Hartman, 1
b. An indication of the capability of the fan to produce pressure. It is
the ratio of the initial depression to the theoretical depression.
Manometric efficiency = 4,380 total water gage / U2 , where U =
tip speed in feet per second of fan blades. Nelson
c. The chief value of the manometric efficiency lies in its being a rough
check on the mechanical efficiency of the fan.
See also:theoretical depression