The sintering or semifusion of ores during roasting. Fay
A device that displays the tracks of charged atomic particles. It is a
glass-walled chamber filled with a supersaturated vapor. When charged
particles pass through the chamber, they leave a cloudlike track much like
the condensation trail of a plane. This track permits scientists to see
the paths of these particles and study their motion and interaction.
See also:bubble chamber; spark chamber. Lyman
Chalcedony with irregular or indistinct patches of color.
See also:agate
Chalcedony with dark, cloudy spots in a light-gray transparent base.
Schaller
In mica, a cloudlike effect that occurs in various colors. Skow
Scot. A mineral related to asphalt, occurring in patches in blue limestone
and in blue flags at Inganess, Orkney. It is soluble in benzol and at a
red heat gives off a large amount of illuminating gas. Fay
a. A bend in a roadway or passage in a coal seam. CTD
b. A large fall of roof. CTD
c. A tough fireclay. CTD
See:botryoid
A rolling mill in which each of the two working rolls of small diameter is
supported by two or more backup rolls. ASM, 1
Strata containing coalbeds, particularly those of the Pennsylvanian
Period. Used as a proper name for a stratigraphic unit more or less
equivalent to the Pennsylvanian Period. Abbrev. of Coal Measures.
AGI
A fine-coal dewatering machine consisting of two rotating elements, an
outside conical screen frame, and an inside solid cone, which carries
spiral hindrance flights. By a slight difference in the number of teeth in
the gears, the screen element moves slightly faster, in the same
direction, than the solid cone. Material enters the machine from the top
and falls on the solid cone where centrifugal force throws it against the
screen. It slides down the screen until it meets the upper end of the
hindrance flights, and, in doing so, the water begins to pass through the
screen. The flights spiral downward, and, as the screen moves slowly
around them in the direction of the downward pitch, the solids gradually
find their way to the bottom of the screen basket and the zone of maximum
centrifugal force, tending to remove all of the water.
See also:dewatering
a. The binding of individual particles to form flocs or agglomerates and
thus increase their rate of settlement in water or other liquid.
See also:flocculation
b. The coalescence of fine particles to form larger particles.
A soluble substance, such as lime, which, when added to a suspension of
very fine solid particles in water, causes these particles to adhere in
clusters that will settle easily. Used to assist in reclaiming water used
in flotation. Hess
A readily combustible rock containing more than 50% by weight and more
than 70% by volume of carbonaceous material, including inherent moisture;
formed from compaction and induration of variously altered plant remains
similar to those in peat. Differences in the kinds of plant materials
(type), in degree of metamorphism (rank), and in the range of impurity
(grade) are characteristic of coal and are used in classification.
Syn:black diamond
The determination, by chemical methods, of the proportionate amounts of
various constituents of coal. Two kinds of coal analyses are ordinarily
made: (1) proximate analysis, which divides the coal into moisture
(water), volatile matter, fixed carbon, and ash. Percentage of sulfur and
heat value in Btus per pound or kilogram, each obtained by separate
determination, are usually reported with the real proximate analysis; and
(2) ultimate analysis, which determines the percentages of the chemical
elements carbon, hydrogen, oxygen, nitrogen, and sulfur. Other elements
that may be present are considered impurities and are reported as ash.
Noncombustible matter in coal.
A special type of continuous miner. It consists essentially of a large
diameter screw drill that cuts, transports, and loads coal onto vehicles
or conveyors. The coal auger is used for (1) winning opencast coal without
stripping overburden; (2) pillar-and-stall mining; and (3) extraction of
pillars or percentage of pillars that would otherwise be uneconomic to
work. See also:auger; twist drill; mole mining. Nelson
Nodules of spheroidal, lenticular, or irregular shape containing petrified
plant remains and in some cases animal remains. They vary in size from
about 1 to 40 cm or more; occasional specimens weigh more than 1 ton.
Infrequently, an entire seam in a restricted area consists largely of coal
balls. Coal balls consist mainly of calcareous, dolomitic, sideritic,
pyritic, or siliceous material surrounding or impregnating plant and
animal remains. They occur in brown coals (mainly sideritic balls) as well
as in coals of higher rank generally lying within a coal seam but
occasionally in the roof. Calcareous, dolomitic, and pyritic coal balls
are commonly found in seams having marine strata in the roof. The
distribution in seams is variable. They may occur in a broad zone running
through a coalbed or be distributed irregularly in nests.
Syn:torf dolomite
An exposed seam of coal. Craigie
A protective pillar of coal. See also:barrier pillar