A timber or metal sill placed transversely under the rails of a railroad,
tramway, or mine-car track. Fay
A technique for testing the validity of a variogram model by kriging each
sampled location with all of the other samples in the search neighborhood,
and comparing the estimates with the true sample values. Interpretation of
results, however, can often be difficult. Unusually large differences
between estimated and true values may indicate the presence of "spatial
outliers," or points that do not seem to belong with their surroundings.
a. The process of forcing a bucket into the digging, or the mechanism that
does the forcing. Used chiefly in reference to machines that dig by
pushing away from themselves. Nichols, 2
b. Used by some drillers as a syn. for overfeed. CF:overload
Long
c. As used by handsetters, the uneven calking of a diamond resulting in
its being pinched or forced out of its intended position in a bit.
Long
d. To place or set diamonds too closely together in the crown of a bit.
Long
In power shovel nomenclature, crowding is the thrusting of the dipper
stick forward over the shipper shaft; retracting is the reverse of
crowding. Carson, 1
In froth flotation, a slanted board used to direct the rising mineralized
froth toward the overflow lip of the cell. Pryor, 3
The treatment of pregnant cyanide solution to remove air before the gold
is precipitated with zinc dust. Also called Merrill-Crowe process.
a. A tool with a sideclaw, for grasping and recovering broken rods in deep
boreholes.
b. Irregular or zigzag markings found in Tennessee marble. Also called
stylolite. AGI
a. The curved roof of a tunnel. Nichols, 1
b. As used by the drilling and bit-setting industries in the United
States, the portion of the bit inset or impregnated with diamonds formed
by casting or pressure-molding and sintering processes; hence the steel
bit blank to which the crown is attached is not considered part of the
crown. Syn:bit crown
c. A timber crossbar up to 16 ft (5 m) long, supported by two heavy legs,
or uprights, one at each end. Crowns may be set at 3-ft (1-m) intervals;
sometimes a roof bolt is put up through the center of the crown.
Nelson
d. The topmost part of a drill tripod, derrick, or mast. Long
e. The part of a furnace forming the top or roof.
f. The top or highest part of a mountain or an igneous intrusion; the
summit. AGI
g. The practically undisturbed material still in place and adjacent to the
highest parts of the scarp along which a landslide moved. AGI
A pulley, set of pulleys, or sheaves at the top of a drill derrick on and
over which the hoist and/or other lines run. Also called crown pulley;
crown wheel. Long
See:bit mold
In mining, a falling of the mine roof or a heave of the mine floor due to
the pressure of overlying strata. CF:creep
The heaving or lifting of the floor beds along a roadway to form a ridge
or crown along the centerline. Nelson
See:bit life
See:bit mold
An ore pillar at the top of an open stope left for wall support and
protection from wall sloughing above.
A piece of timber set on props to support the mine roof. Zern
a. A wheel driven by a pinion, notably in the drive of a ball mill.
Largest wheel of any reduction gear. Pryor, 3
b. Syn:crown block
A variety of finely crystallized barite. Standard, 2
The hearth of a blast cupola, or open hearth furnace; a refractory vessel
for melting or calcining metals, ores, etc.
See:assay; lead button.
Ball clays that are relatively refractory; used in producing crucibles
that will withstand high temperatures. CCD, 2