combination electric locomotive
A mine locomotive that can operate as a trolley locomotive or as a battery
locomotive. While operating on a battery, it can be used, under certain
conditions, at the coal face. Also it may be used on the main haulage
trolley system where, due to higher voltage, higher speeds are possible.
Nelson
See:longwall
Method for extracting alumina from high-silica bauxites, in which the
bauxite is first subjected to a Bayer process caustic leach. The resulting
red mud, containing sodium aluminum silicate, is sintered with limestone
plus soda ash and then leached with water to recover alumina and soda.
a. A rig comprising a complete cable-tool outfit and a complete rotary
outfit. Porter
b. See:combination drill
A universal-type soil-sampling device in which some of the constructional
features of two or more special-use samplers are combined. Long
See:combined overhand and underhand stoping
The part of the total carbon in steel or cast iron that is present as
other than free carbon. ASM, 1
Moisture in coal that cannot be removed by ordinary drying.
CF:free moisture
combined overhand and underhand stoping
This term signifies the workings of a block simultaneously from the bottom
to its top and from the top to the bottom. The modifications are
distinguished by the support used, as open stopes, stull-supported stopes,
or pillar-supported stopes. Also known as combined stopes; combination
stoping; overhand stoping and milling system.
Syn:back and underhand stoping milling system; combination stoping.
combined shrinkage stoping and caving
In this method, the orebody is worked from the top down in successive
layers of much greater thickness than in top slicing. The mass of ore is
weakened by a series of shrinkage stopes, which are extended up between
the ribs, pillars, or blocks, which are subsequently caved. The
intervening blocks are under cut and caved as in block caving. The caver
follows the caved ore. Also called overhand stoping with shrinkage and
simultaneous caving.
combined side and longwall stoping
See:overhand stoping
Any state of stress that cannot be represented by a single component of
stress; i.e., one that is more complicated than simple tension,
compression, or shear. ASM, 1
combined top slicing and shrinkage stoping
In this method, the orebody is worked from the top down in successive
slices. In the working of each slice, the unit is worked as a shrinkage
stope. The broken ore serves to give lateral support to the sides of the
unit and also serves as a working platform from which the back is reached.
After working a unit, the cover is caved. No timber mat is used. Also
known as the Kimberley method.
A rare type of twinning in quartz in which there appears to be a 180
degrees rotation around c with reflection over (1120) or over (0001). The
crystal axes are parallel, but the polarity of the a axis is not reversed
in the twinned parts.
A texture in which individual crystals have their long axis perpendicular
to the walls of a vein. See also:comb
An assessment of the speed of combustion of a coal under specified
conditions. BS, 4
Capable of undergoing combustion or of burning. Used esp. for materials
that catch fire and burn when subjected to fire. CF:flammable
Webster 3rd
See:firedamp
A small cap that forms over the flame of a safety lamp when sufficient
combustible gases (methane) are present. CTD
The collection of combustible gases from coal measures strata, generally
into pipes, with or without the use of suction.
See also:methane drainage
The zone of contact between the goaf gases and the ventilation air current
at the face. Roberts, 1