Surface mining that progresses in a narrow zone following the outcrop of a
coal seam in mountainous terrain, and the overburden, removed to gain
access to the mineral commodity, is immediately placed in the previously
mined area, such that reclamation is carried out contemporaneously with
extraction. SME, 1
A plan drawn to a suitable scale showing surface contours or calculated
contours of coal seams to be developed. These plans are important during
the planning stage of a project. See also:interpolation of contours
Nelson
A watercourse following the contour of the country.
In coal mining, a term meaning cigars, cigarettes, pipes, and other
contrivances for smoking, matches, and mechanical lighters. It is a
violation of safety regulations to take contraband below ground or to have
contraband in one's possession below ground. Nelson
a. A bargain or agreement voluntarily made upon good consideration,
between two or more persons capable of contracting to do, or forbearing to
do, some lawful act. Hoover
b. In mining, applies to an agreement between operator and worker to pay
the latter so much per foot for excavating drift or stope. These people
are known as contract miners and are usually skilled workers. They work
harder than people on wages due to the incentive of higher earnings.
Weed, 2
c. Agreement between contractor and employing company to construct, erect,
install, and operate specified works under agreed conditions. A cost-plus
contract is one in which the contractor undertakes a comprehensive
activity, part of which may be subcontracted (or let out). A unit contract
is one in which company awards a restricted part of the job to the
contractor. See also:agreement
The bulk of the contraction that accompanies the solidification of metals
is concentrated in the feeder heads and risers, from which molten metal
flows to compensate for contraction in the casting of ingot proper.
CTD
A vein formed by the filling of a fissure caused by contraction resulting
from the drying or cooling of the surrounding rock.
In bituminous coal mining, one who is paid a certain rate per ton of car
of coal mined, and employs one or more loaders whom the loader pays out of
personal earnings. DOT
a. In anthracite and bituminous coal mining, one who operates electric or
compressed-air machines to drill holes into the working face of coal or
rock for blasting, and shovels coal into cars after blasting. A contract
miner is usually engaged in production work, i.e., the mining of coal
only, and is paid on a tonnage basis. In anthracite regions, the miner is
paid the wage rate of a consideration mine when encountering obstructions
of rock or slate that prevent earning an amount in excess of a fixed or
specified rate per day. Also called contract driller; contract
drilling-machine operator; contract contractor. DOT
b. In metal mining, one who drills, blasts, and loads ore or rock into
cars in a mine. Is usually engaged in production work, i.e., the mining of
ore only, and is paid on a contract basis (so much per ton, cubic yard, or
cars of ore produced). DOT
a. The person who signs a contract to do certain specified work at a
certain rate of payment. In mining, the contractor is an experienced miner
or hard-heading miner. He or she employs other people and the work may
proceed on a three-shift basis. Nelson
b. S. Afr. Mine worker undertaking special tasks on a contractual basis
such as shaft sinking, development blasting, etc. Beerman
See:contract miner
Work that is outside the scope of the mine price list and is performed on
the basis of an agreement between a miner and the mine manager. The
agreement may be only verbal and renewable weekly or monthly. Payment is
made according to performance. In development work, the contract rate is
usually per yard advance. There may be bonus payments for good work or for
extra performance. See also:piecework
Stream aggradation caused by an obstruction. Syn:dam gradation
A modification of the axial-flow fan. It consists of two impellers with
aerofoil shaped blades that rotate in opposite directions. The drive is by
means of a single motor through differential gears, or two separate
motors, one for each impeller. They are placed in the airstream and act as
streamlined hubs. These fans are available for auxiliary ventilation in
mines. See also:axial-flow fan
In mining, means that the law imposes upon every person the duty of using
ordinary care for his or her own protection against injury. It is not
synonymous with assumption of risk. Ricketts
a. The dimensional data used to establish the position, elevations, scale,
and orientation of the detail of a map and that are responsible for the
interpretations placed on a map. AGI
b. A section or reach of an open channel in which natural or artificial
conditions make the water level above it a stable index of discharge. It
may be either complete (i.e., water-surface elevation above the control is
completely independent of downstream water-level fluctuations) or partial;
it may also shift. AGI
c. That waterway cross section that is the bottleneck for a given flow and
determines the energy head required to produce the flow. In an open
channel, it is the point at which flow is at critical depth; in a closed
conduit, it is the point at which hydrostatic pressure and cross-sectional
area of flow are definitely fixed, except where the flow is limited at
some other point by a hydrostatic pressure equal to the greatest vacuum
that can be maintained unbroken at that point. AGI
d. Any of the factors determining the nature of geologic formations at a
given place. Webster 3rd
e. In geology, the background and the quantity of data that are
responsible for the interpretation placed on a map or a cross section.
AGI
f. An attempt to guide a borehole to follow a predetermined course through
the use of wedges or by manipulation of the drill string. Long
An assay made by an umpire to determine the basis on which a purchaser is
to pay the seller for ore. See also:umpire
Graph showing, horizontally, the operating norm and also the upper and
lower control limits within which deviations must be held. Should these
values exceed the permitted variance, special steps must be taken to
locate and correct the upsetting factor or factors. Pryor, 3
Techniques used to control overbreak and produce a competent final
excavation wall. See also:line drilling; smooth blasting;
cushion blasting. Syn:presplitting
A mining method utilizing the advantages of longwalls, but at the same
time without filling. In this method, the working room in front of the
working face is protected by close lines of props and cribs, which are
portable and easily taken to pieces. As the face proceeds, the cribs are
shifted as well as the props with the face, leaving the mined-out room to
cave. This method is also called mining with self-filling. Stoces
Cooling from an elevated temperature in a predetermined manner to avoid
hardening, cracking, or internal damage, or to produce a desired
microstructure. This cooling usually follows a hot-forming operation.
ASM, 1