Low-temperature quartz; when formed below 573 degrees C, SiO2
tetrahedra are less symmetrically arranged than at higher temperatures;
inversion is reversible. Syn:alpha quartz
See:rank
Metamorphism that is accomplished under conditions of low to moderate
temperature and pressure. CF:high-rank metamorphism
Temperature of iron at which redness is observable in subdued daylight
(525 to 700 degrees C). Bright red heat is in the range 700 to 1,000
degrees C and is followed by orange at 1,000 degrees C, white at 1,300
degrees C, and blue-white at 1,500+ degrees C. Pryor, 3
A short shaft-type blast furnace that can be used to produce pig iron and
ferroalloys from low-grade ores, using low-grade fuel. The air blast is
often enriched with oxygen. It can also be used for making a variety of
other products such as alumina, cement-making slags, and ammonia synthesis
gas. ASM, 1
Carbonization carried out at a low temperature (between 500 degrees C and
700 degrees C). During the process, the smoke-producing compounds are
driven off as tars and oils and collected as valuable byproducts, leaving
a coke with about 10% volatile matter. The coke yield is about 1,400 lb/st
(700 kg/t) and is used as a domestic fuel. Nelson
A solid fuel produced by the low-temperature carbonization of coal.
Nelson
low-temperature incineration method
In this method for the determination of incombustible matter, the mine
roadway dust (dust containing carbonates) is incinerated at a temperature
of not less than 500 degrees C and not more than 530 degrees C until it is
constant in weight. This temperature is sufficient to complete the
combustion of the organic matter in the dust, but is not high enough to
decompose the carbonates. However, this method is unsuitable for dust
containing magnesium carbonate because this substance decomposes below 500
degrees C, and therefore a low result for the incombustible matter would
be obtained. The moisture content of the sample may be calculated so that
an allowance can be made for the weight loss attributed to moisture.
Cooper
A detonator requiring a minimum current of 1 A for firing and having a
resistance of about 1 Omega . BS, 12
Aust. Gravel and shingle in terraces.
See:velocity
The rank of coal, within the bituminous class of Classification D 388,
such that, on the dry and mineral-matter-free basis, the volatile matter
content of the coal is greater than 14% but equal to or less than 22% (or
the fixed carbon content is equal to or greater than 78% but less than
86%), and the coal commonly agglomerates. CF:bituminous coal
ASTM
In coal mining, 660 V or less. Also called low potential.
CF:high voltage; medium voltage. Federal Mine Safety
Low working voltage in coal mines is one of the many conditions that must
be given continual attention. Loss of voltage means a proportional loss in
power. Since the quantity of dc power is obtained by multiplying the
number of amperes times the number of volts, it follows that for a given
amount of power if the volts are lowered the amperes are increased, and
the increase in amperes results in an increase in power loss in the mine
circuit. Lower operating voltages result in heavier currents in the dc
motor circuits, thus heating the motors, cables, and circuit wiring and
causing loss in motor speed, inefficient operation, and increased
maintenance cost. Kentucky
A form of cut stone produced by the meeting of the skill and star facets
on the benzil of brilliants; or by the meeting of the facets in the
horizontal ribs of the crown. Hess
To determine the horizontal compass direction that a borehole is trending
at a specific depth by means of one of several borehole surveying
instruments. Long
Long period delays used in delay blasting underground and generally
available in intervals of seconds.
A fibrous variety of calcite.
The act of applying lubricants. There are two main types of lubricants,
solid and liquid. Examples of the solid type are graphite, French chalk,
and sulfur. Liquid lubricants are by far the more important, and among
these, oils and greases are the most common. Crispin; Morris
A modification of the Pattinson process whereby the molten lead is stirred
by the injection of steam; used in desilverizing base bullion. Fay