There are two methods: (1) Long holes are drilled parallel to the coal
face. Charges of Hydrobel explosive are spaced along the holes and fired
under water pressure. The object is to loosen the coal and allay the dust
along the entire face in one operation.
See also:pulsed infusion shot firing
about 40 ft (12.2 m) long in the line of advance of the workings. The
holes are not charged with explosive and fired but only subjected to water
pressure up to 3,000 psi (20.7 MPa) to loosen the coal and allay the dust
in the cleats. The holes may be drilled during weekends and of a length
about equal to the weekly advance of the face. Nelson
A hydraulic mining system consisting essentially of drilling a hole down
the pitch of the vein, replacing the drilling head with a jet cutting
head, and then retracting the drill column with the jets in operation to
remove the coal. Coal cut loose by the jets drops to a flume drift and is
carried by water to a screening and loading plant. Coal Age, 3
A fault whose strike is parallel with that of the general structural trend
of the region. AGI
A fissure that is parallel with the strike of the deposit. Stoces
A steeply dipping joint plane in a pluton that is oriented parallel to the
lines of flow. Syn:S-joint; bc-joint. AGI
A trace on the ground motion record representing the component of motion
in a horizontal plane and in the direction of the seismic wave travel
direction. Syn:radial axis
See:strike valley
An elastic wave in which the displacements are in the direction of wave
propagation. Syn:P wave; primary wave. AGI
Partially aerated flames, particularly when aerated in stages.
Nonturbulent flow. Francis, 2
Method of recovering copper from burned sulfides, by roasting with rock
salt and using the issuing gases, after condensation, to leach the
chloridized residue. Copper then dissolved is precipitated from the leach
liquor onto scrap iron. Pryor, 3
An appliance to provide a constant flow of coal from a continuous miner to
the main haulage system. It consists of a conveyor slung under the tail
end of the loader and running on a bogey straddling the heading conveyor
so that it can telescope over it. Nelson
Coal winning in three stages in underground mining. First, large pillars
are left as the face is advanced by means of drives. Second, parallel
drives connect these drives and form large blocks. Finally, the pillars so
formed are mined. Pryor, 3
The property of crystal structures wherein atomic particles show
periodicity over large numbers of atomic diameters and each atomic
particle has specific relationships with lattice points.
CF:short-range order; disorder. See:superlattice; superstructure.
To fill or nearly fill the core barrel with core on a single trip into the
borehole. CF:short run
long-running thermal precipitator
A dust-sampling instrument designed by the Mining Research Establishment
of Great Britain that operates over periods of up to 8 h and collects only
respirable dust that is selected aerodynamically during the sampling
process. The respirable fraction is selected by drawing the dust through a
horizontal duct elutriator that simulates the acting principle of the
human nose and respiratory passages in that the larger and faster-falling
particles are caught by the processes of settlement and impingement.
Roberts, 1
A section of land that contains more than 640 acres (256 ha).
Williams
A steel chisel-edged chopping bit having a longer and heavier-than-normal
shank, designed to give added weight and directional stability when
chopping an angle hole through overburden. Long
A current in the surf zone, moving generally parallel to the shoreline,
generated by waves breaking at an angle with the shoreline.
Syn:littoral current
See:beach drift
A trough for washing gold-bearing earth. It is longer than a rocker.
Webster 3rd; Fay