Hard metal ridge applied to the outside surface of bottom-hole equipment
and built up as close as practicable to the set-outside-diameter size of a
reaming shell, which serves as a wear pad. Long
a. To undergo changes, such as discoloration, softening, crumbling, or
pitting of rock surfaces; brought about by exposure to the atmosphere and
its agents. AGI
b. To undergo or endure the action of the elements; to wear away,
disintegrate, discolor, or deteriorate under atmospheric influences.
Webster 3rd
A door in a mine level whose purpose it is to regulate ventilation
currents. A trapdoor. Fay
a. In seismic work, a zone extending from the surface to a limited depth,
usually characterized by a low velocity of transmission, which abruptly
changes to a higher velocity in the underlying bedrock. The name is
erroneous, and the zone is more properly called the low-velocity layer.
AGI
b. In seismology, the zone of the Earth that is immediately below the
surface, characterized by low seismic-wave velocities. AGI
Rock, the character of which has been changed by exposure to decaying
conditions found in the zone of weathering. Long
a. The destructive processes by which earthy and rocky materials on
exposure to atmospheric agents at or near the Earth's surface are changed
in color, texture, composition, firmness, or form, with little or no
transport of the loosened or altered material; specif. the physical
disintegration and chemical decomposition of rock that produce an in-situ
mantle of waste and prepare sediments for transportation. Most weathering
occurs at the surface, but it may take place at considerable depths, as in
well-jointed rocks that permit easy penetration of atmospheric oxygen and
circulating surface waters. AGI
b. Exposing ore to the atmosphere for long periods in order that a part,
at least of the sulfide content, may become oxidized and washed away by
the rain. Osborne
c. See:seasoning
In seismic exploration, a correction applied to reflection and refraction
data for variations in travel time produced by irregularities in a
low-velocity or weathered layer near the surface.
Syn:low-velocity-layer correction
A measure of the weathering characteristics of coal, according to a
standard laboratory procedure. Syn:slacking index
In seismic work, a map on which the low-velocity layer, or weathered
layer, is plotted and contoured to show areal variations. AGI
The slow disintegration of coal into fires in surface stockpiles under the
action of the weather, particularly frost after a wet period.
See also:spontaneous combustion
The disintegration or scaling of exposed surfaces of mine roadways,
particularly in the case of clay or shale rocks. Gunite has been used for
roadway protection against weathering. See also:guniting
Nelson
In seismic exploration, the detonation of a small explosive charge in the
weathering or low-velocity layer to determine its velocity characteristics
and thickness. AGI
The slice or thickness of coal taken by a cutter loader when cutting along
the face. The thickness of a web varies from a few inches with plow-type
machines to up to about 6 ft (1.8 m) with the A.B. Meco-Moore. The term
web tends to be restricted to thin or medium slices of coal.
See also:buttock
Magnetic flux equivalent in the meter-kilogram-second (mks) system of the
maxwell in the centimeter-gram-second (cgs) system. One weber equals 10
8 maxwells. Abbrev., wb. Pryor, 3
An orthorhombic mineral, Na2 MgAlF7 ; pale gray; forms
grains in cryolite; in Greenland.
A method of manufacturing pig iron in which the ore is mixed with a
proportionate amount of coal sufficient to smelt it; after adding a binder
the mixture is briquetted by means of a roller press into ovoids, which
are subjected to low temperature carbonization between 550 degrees C and
600 degrees C, followed by smelting in a low shaft furnace.
Osborne
A tetragonal mineral, Ca(C2 O4 ).2H2 O ; in mud at
the bottom of the Weddell Sea, Antarctica; also as urinary calculi.
CF:whewellite
a. A wedge-shaped piece of wood used to tighten timber sets against the
roof and sides. See also:lag; lid. Nelson
b. A tapered piece of material used to initiate the deflection of a
borehole. See also:deflecting wedge; Hall-Rowe wedge. Long
c. Tapered piece of core that tends to bind and block a core barrel.
Long
d. A piece of mica that, on splitting, yields pieces thicker at one end
than at the other. Skow
e. The shape of a stratum, vein, or intrusive body that thins out; specif.
a wedge-shaped sedimentary body, or prism. See also:prism
A bolt designed for use in roof bolting. It consists of a rod 1-3/4 in
(4.45 cm) in diameter with one end threaded and the other end shaped to
form a solid wedge. A loose split sleeve with an outside diameter of 1-1/2
in (3.81 cm) is fitted over the wedge. Anchorage is provided when the bolt
is pulled downward in a hole and the sleeve is held by a thrust tube.
Split by the wedge head of the bolt, the sleeve expands until it grips the
sides of the hole. See also:bolt; slot-and-wedge bolt. Nelson
A tapered-nose noncoring bit, used to ream out a borehole alongside a
steel deflecting wedge in hole-deflection operations. Also called:
bullnose bit; wedge reaming bit. Syn:wedging bit
A winding rope capping consisting of two tapered iron wedges that encircle
the rope, the end of which is prevented from unravelling by casting onto
it a small block of white metal. The wedges are contained by a steel bow,
over which four or five wrought-iron hoops are driven. The greater the
pull on the rope, the more the wedges grip it as they are drawn into the
encircling hoops. Mason