In copper smelting, a kind of converter with horizontal tuyeres, to
produce bottoms and a purified copper in one operation.
Webster 3rd
Sometimes used to designate the best quality of industrials normally used
as drill diamonds. Long
a. Finely crystallized gypsum. Cooper
b. A clear, colorless variety of gypsum, occurring (esp. in clays) in
distinct, transparent monoclinic crystals or in large crystalline masses
that cleave easily into broad folia. Syn:spectacle stone
In mineralogy, a plate of selenite that gives a purplish-red interference
color of the first order with crossed polars. Syn:gypsum plate;
unit retardation plate; sensitive-tint plate; first-order red plate;
Red I plate; Rot I plate.
A nonmetallic element and member of the sulfur family. Symbol, Se. It is
widely distributed in small quantities, usually as selenides of heavy
metals. Obtained from electrolytic copper refining. Used in photocells,
exposure meters, and solar cells, and extensively in rectifiers.
Handbook of Chemistry and Physics, 3
See:laitakarite
a. Wadsworth's name for rocks composed of gypsum or anhydrite. Fay
b. A mineral, Pb2 (SeO4 )(SO4 ) , reported as white
needles with cerussite and molybdomenite at Cacheuta, Argentina.
Dana, 2
c. Former name for olsacherite.
d. Discredited name for downeyite, SeO2 .
See:gravity haulage
A ventilation door consisting of two halves, so constructed that they are
forced apart centrally by the trams as they come in contact with the
converging beams that operate them. The door halves move on small pulleys
that run on inclined rails so that after the passage of the trams the door
closes by gravity. Nelson
a. In transport by mine car, a brake incline. See also:brake incline
Pryor, 3
b. See:gravity haulage
An inclined plane upon which the weight or force of gravity acting on the
full cars is sufficient to overcome the resistance of the empties; in
other words, the full car, running down, pulls the other car (empty) up.
A system of rope haulage used for transporting material on the surface and
to transfer loaded cars from one elevation to a lower one in mines. Slope
must be sufficiently steep so the loaded cars will pull the empty cars up
the grade. Syn:gravity plane rope haulage
An assembly of hydraulically operated steel hydraulic supports, on a
longwall face, that are moved forward as an integral unit by means of a
hydraulic ram coupled to the heavy steel face conveyor.
Syn:power-operated supports; walking props. See also:hydraulic chock;
steel prop. Nelson
A belt idler that controls and limits the side runout of the carrying belt
within practical limits by means of a swivel mechanism. NEMA, 2
A belt idler that controls and limits the side runout of the return belt
within practical limits by means of a swivel mechanism. NEMA, 2
A term applied to metals, such as lead, tin, and zinc, that recrystallize
at air temperature and in which little strain hardening is produced by
cold working. CTD
A drill chuck that, when closed, automatically positions the drill rod in
the center of the drive rod of a diamond-drill swivel head. Long
A conveyor belt structure tail pulley which is designed with vanes along
the length of the tail pulley and often is hollow in the center to allow
any spillage along the return belt to end up at the tail pulley, which
allows it to fall to the sides to eliminate the debris.
The gradient at which flow in a pipe of a particular diameter will carry
away any solids in it. This gradient must not be too steep nor too
gradual, and is usually established under local laws affecting drains and
sewers. Hammond
self-contained breathing apparatus
A self-sufficient breathing unit that permits freedom of movement,
unencumbered by air hoses. It offers the wearer respiratory protection in
atmospheres that are either oxygen-deficient or too highly toxic to permit
the use of gask masks or respirators. The oxygen or air is supplied in
compressed form or by chemical generation, and the wearer's exhalations
are either purified for re-use or released to the surrounding atmosphere.
The equipment is devised to afford protection for special lengths of time,
in accordance with the standards set by the Mine Safety and Health
Administration. The 2-h apparatus is used for mine rescue and recovery
operations; shorter period apparatus is available for industrial uses and
auxiliary equipment. Best, 1
self-contained portable electric lamps
Electric lamps that are operated by an electric battery; designed to be
carried about by the user of the lamp. Fay