A drill mounting often made at the mine to suit the tunnel requirements.
It usually comprises two girders strapped together to form a replica of
the tunnel shape but smaller in size. The structure is mounted on wheels
and provision is made for clamping the drills to various parts of the
frame according to the drill-hole pattern in use. It contains a central
opening to allow the passage of the loading machine, cars, or conveyor.
Nelson
The width across the cutting bit or diameter of the drilled hole. With
tungsten-carbide bits it is possible to drill long holes without the loss
of gage. Nelson
a. A hole in rock or coal made with an auger or a drill.
b. Technically, a circular hole drilled by forces applied percussively;
loosely and commonly, the name applies to a circular hole drilled in any
manner. Long
c. Used by diamond drillers as a syn. for borehole. CF:borehole
Long
When the results of a survey indicate a possible ore deposit, test holes
may be drilled and a special adaptation of a scintillation counter, called
a drill-hole counter, may be lowered in a hole in an attempt to locate,
outline, and assay an orebody. The drill-hole counter can distinguish
between formations by their radiation intensity. Dobrin
The number, position, depth, and angle of the shot holes forming the
complete round in the face of a tunnel or sinking pit. A good drill-hole
pattern will ensure the maximum possible pull and the fragmentation for
easy loading without excessive scatter of material. See also:cut holes
Nelson
A description of the borehole based on the daily logs from the driller and
the samples and the report of the geologist. Nelson
The circulation fluid and entrained cuttings overflowing the collar when
drilling a borehole. Long
See:borehole survey
a. The act or process of making a circular hole with a drill.
See also:drill
b. The operation of tunneling or stoping, whether with a compressed-air
rock drill, a jackhammer, or a drifter. CTD
c. Use of a compressed-air rock drill to prepare rock for blasting.
Pryor, 3
d. The operation of making deep holes with a drill for prospecting,
exploration, or valuation. Pryor, 3
The cutting device at the lower end of cable drilling tools or rotary
drill pipe, the function of which is to accomplish the actual boring or
cutting. AGI
See:cable
The column of drill rods to the end of which the bit is attached.
BS, 9
Time spent in circulating a higher-than-normal volume of fluid through the
drilling string while slowly rotating and lowering the string from the
last few feet above to the bottom of a borehole to wash away any
obstructing material before resuming coring operations. Long
a. A device very accurately made of cast or wrought iron that becomes a
guide for the drilling of holes. The work is fastened in the jig, and the
drill is guided through holes drilled in the face of the jig itself. The
use of a jig makes interchangeable work easily obtainable. Crispin
b. A portable drilling machine worked by hand. Fay
See:bit life
A hand-operated, or power-driven machine for boring shot holes or
boreholes, in coal, ore, mineral, or rock. See also:drifter drill;
percussive drill; rotary drill; rotary-percussive drill. Nelson
A suspension, generally aqueous, used in rotary drilling and pumped down
through the drill pipe to seal off porous zones and to counterbalance the
pressure of oil and gas; consists of various substances in a finely
divided state among which bentonite and barite are most common. Oil may be
used as a base of water. CF:circulation fluid; mud-laden fluid.
AGI
The relation of drilled holes to each other and any free faces as part of
the blast design.
Auxiliary equipment for drilling at heights above head level. The drilling
platform is generally assembled and dismantled for each series of drilling
operations. Fraenkel
See:bit load
a. The depth of penetration achieved per unit of time with a given type of
rock drill, bit diameter, air pressure, etc. See also:penetration rate
Fraenkel
b. The overall rate of advancement of the borehole. BS, 9