a. A machine for extracting gold from dry gravel. It consists of a frame
in which there is a rectangular bellows made of canvas; the upper part of
the bellows is made by a plane set at an angle of about 20 degrees ,
across which are riffles. On the top of the machine is a screen on which
gravel is shoveled. The screened gravel falls to a riffled plane from
which it feeds to the riffles on the bellows. The screen and upper riffles
are shaken by an eccentric worked with a crank, and the same crank
actuates the bellows, which blow the dust from the gravel passing over the
riffles. The gold is caught behind the riffles. Only gravel in which no
moisture can be seen can be worked successfully by a dry washer.
Hess
b. A person who operates a dry washer. Syn:dry blower
A deep hole, covered and usually lined or filled with rocks, that holds
drainage water until it soaks into the ground. Nichols, 1
A conveyor having a belt drive mechanism in which the conveyor belt is in
contact with two drive pulleys, each of which is driven by a separate
motor. NEMA, 2
In strip mining, the use of two types of haulage at the same mine for
transporting coal from the face to the preparation plant. Usually, coal is
transported from the loading shovel to a transfer station by motorized
units, and rail haulage is used to haul the coal from this point to the
preparation plant. Toenges
A variety of dynamite consisting of four to five parts nitroglycerin,
three parts sawdust, and two parts potassium nitrate. Webster 2nd
Slate size of 24 in by 12 in (61.0 cm by 30.5 cm). Pryor, 3
A fabric material, usually of woven cotton but of synthetic fibers also,
used to construct conveyor belts and filter cloths. Pryor, 3
The name given to a shaking-type combination loading and conveying device,
so named from the shape of its loading end and which generally receives
its motion from the shaking conveyor to which it is attached. BCI
In bituminous coal mining, one who operates a small power shovel that has
a round-nosed scoop, called a duckbill, to load coal into cars in a mine.
DOT
A duckbill-shaped coal-cutter pick that is forged by the roller type of
machine from dies and is the type largely used today. The machine shaping
of the pick ensures uniformity. It gives a constant clearance as the point
wears down and is particularly suitable for fused-carbide tipping.
Nelson
A pipe bend at the bottom of a shaft column or rising main fitted with a
horizontal base sufficiently strong for the weight of the rising main to
rest upon it. Also called duckfoot bend. BS, 10
See:duckfoot
An arrangement of two boxes, one working within the other, for forcing air
into mines. Zern
A tuyere having a cupped outlet. Standard, 2
An intimate mixture of pyrite and chalcocite or the matrix of a blackish
copper ore containing grains of pyrite, Tennessee.
Abbrev. for dust concentrator, which is a device used to collect dry
cuttings ejected from a borehole in which air or gas is used as a
circulation medium. Long
A pipe or tubing used for auxiliary ventilation in a mine. Generally
constructed of coated fabric, metal, or fiberglass.
An axial-flow fan mounted in, or intended for mounting in, a section of
duct. See also:tube-axial fan; vane-axial fan;
mine ventilation auxiliary fan.
a. Said of certain metals and other substances that readily deform
plastically.
b. Said of a rock that is able to sustain, under a given set of
conditions, 5% to 10% deformation before fracturing or faulting.
AGI
c. In mineralogy, capable of considerable deformation, esp. stretching,
without breaking; said of several native metals and occasionally said of
some tellurides and sulfides. AGI
d. Pertaining to a substance that readily deforms plastically. AGI
e. Capable of being permanently drawn out without breaking; such as, a
ductile metal. Webster 3rd