Eng. A clause inserted in some mining leases providing for an abatement of
royalty or allowance on weight for certain weight of small coal or
breakage sent out in every ton of large coal, for example, 120 lb (54.5
kg) in every collier's ton of 2,640 lb (1,200 kg).
See:degradation
A chain that holds a tractor and a towed unit together if the regular
fastening opens or breaks. Syn:safety chain
The fractures caused by the shattering of a solid rock ledge back of the
drill holes in which the charge is placed. Fay
A scraper capable of detecting breaks in a shothole. See also:break;
stemmer. Nelson
Of an emulsion, the reunion of the finely dispersed particles and their
separation from the medium in which they form an emulsion. Syn:hoedown
CTD
The voltage at which an insulator or dielectric ruptures; or the voltage
at which ionization and conduction begin in a gas or vapor. Hunt
The ability of a switch, in a particular situation, to clear safely the
heaviest fault current that can flow; it depends upon the amount of power
available in the system, size of cables, transformers, etc.
CF:breaking capacity
Props, or props and cribs, set to break the roof off at a prearranged line
during retreat mining, or when blasting down roof.
The row of drill holes above the mining holes in a tunnel face.
Stauffer
See:surf zone
Eng. Fissures in old coal workings. See also:break
a. Production level at which total cost equals revenue. Pryor, 3
b. Value or selling price of ore, metal, or mined material that just
balances total cost of operations; conversely, maximum unit costs above
which there is no profit at given market values.
To start drilling operations with a new bit by rotating the bit slowly
under a light load for a short time before full speed and load are applied
to the bit. Long
Size reduction of large particles. Also called cracking. BS, 5
The capacity of a switch, circuit breaker, or other similar device to
break an electric circuit under certain specified conditions.
CF:breaker capacity
A rolling mill unit used for breaking-down operations; a rolling mill used
for reducing sectional dimensions, mainly thickness--of ingots, billets,
and other rough, semifinished products--as a preliminary step to
subsequent rolling operations. Henderson
a. The breaking and loosening of rock as a preparatory step to its loading
and removal. See also:excavation
b. Attrition of an ore deposit by hand, explosive, or mechanical breaking
methods to reduce it to pieces of ore suitable for transport and
treatment. Pryor, 3
N. of Eng. See:hewing
a. The first borehole fired in "blasting off the solid" to provide a space
into which material from subsequent shots may be thrown. Also called
opening shot; buster shot. Fay
b. In blasting a solid face, the first hole or group of holes of a round
to be fired simultaneously. See also:burn cut
As applied to an electric blasting cap, the time elapsing between the
bridge wire receiving the firing impulse and the breaking of the circuit.
Fraenkel