a. A spiral casing to a mine fan to provide an area of passage, which
gradually increases in proportion to the increasing area of discharge from
the fan. See also:evase
b. A spiral casing for a centrifugal pump or a fan designed so that speed
will be converted to pressure without shock. Hammond
This type of centrifugal pump is the most commonly used. The impellers may
be open, closed or semienclosed, single suction, double suction, or
nonclogging. They discharge into casings that are progressively expanding
spiral designs of one or more stages (multistage). The casings housing the
rotating elements may be vertically or horizontally split, and a few
designs have casings divided on an angle from the horizontal. Pumps in
this class usually have a specific speed below 4,000 rpm with
single-suction impellers and a specific speed of 5,000 rpm with
double-suction impellers. Pit and Quarry
The pressure peak leading the detonation wave prior to the establishment
of the C-J state. Van Dolah
An orthorhombic mineral, Fe3 BO5 ; ludwigite group; contains
both ferrous and ferric iron with ferrous iron replaced by magnesium
toward ludwigite; black; forms coarse granular masses; at Riverside, CA.
A device for measuring the vertical component of gravity, characterized by
the use of four pendulums in a single case. AGI
A quantitative chemical-mineralogic classification of igneous rocks
proposed in 1922 by F. von Wolff. AGI
See:vug
A coal-cleaning process using a heavy suspension, consisting of clay and
finely ground barite (-150 or #MG200 mesh) in water. A coal containing as
little as 3.3% to 3.4% ash is steadily produced, with a yield practically
equal to the theoretical float-and-sink yield. Gaudin, 1
A white or rose-colored variety of beryl from the Ural Mountains, Russia,
and Madagascar. Syn:morganite
Tube projecting into central vortex of hydrocyclone or dense medium
cyclone through which the classified fines or lighter specific gravity
fraction of pulp leaves the system.
An orthorhombic mineral, Tl4 Hg3 Sb2 As8 S
20 ; forms gray-black crystals or thin red splinters; commonly
intergrown with realgar and orpiment; occurs at Salonika, Macedonia,
Greece.
A small cavity in a rock, usually lined with crystals of a different
mineral composition than the enclosing rock. Adj: vuggy. CF:druse;
miarolitic cavity; geode. Syn:bug hole; vogle; vooga hole.
See also:cavity; vuggy porosity; loch. Etymol: Cornish vooga, cavern or
cavity.
A misspelling of vug. Long
Pertaining to a vug or having numerous vugs. Syn:vugular
A lode or vein in which vugs or drusy cavities are of frequent occurrence.
Fay
Porosity due to vugs in calcareous rock. The term vugular is used by some
writers but condemned by others. See also:vug
When a pocket of rock in the periphery of an excavation is weaker than the
remainder, it may fail under the ring stress. Fragments split away or fall
out until all the weak rock is removed, forming an artificial vugh. This
is called vugh-arching. Spalding
See:vug
See:vuggy
Explosive; used in mines. Bennett
Volcanism.