1940 - part 2 - Vredenburgh.org

An important element in the successful
uae of the equipment is the free floating
piston or hammer designed in the
Worthington drill. This piston has but
one function to perfonn-that is, to hammer
the drill steel. The rotation of the
steel is entirely independent of this piston
or hammer action. A simple, balancedgear
air motor is employed, a feature commonly
called "independent rotation." The
ability of the hammer to continue func­
~tioning, even should rotation stop, supplies
-the means for driving the steel backward
out of the stuck position, enabling the independent
rotation to immediately pick up
its function and keep the steel free. The
possibility of Ustuck steel'" is lessened to
a point where it might be said, for all
practical purposes, to be non-existent. The
operator soon learns all these desirable
peculiarities of this independent rotation
and hammering action and by understanding
it avoids "stuck steel."
At Picacho the equipment included
Worthington WD-33 Tower wagon drills
each equipped with the special vacuum
sample collector and operated by Worthington
816-cubic foot, two-stage, aircooled
full Diesel portable compressors.
It readily can be understood that as the
work progressed, experience was gained
which resulted in modifications not only in
some of the equipment, but in the method
cpursued. In this work the Worthington
staff cooperated with the Picacho organization
to develop and perfect the vacuum
sampling method.
The original vacuum sample collectors
were redesigned and improved and, today,
a sample collector to fit practically any
condition is available. Likewise, many improvements
in the technique of drilling
and the utilization of accessories were
made and adopted.
HILE the Picacho problem was prin.
W cipally to develop ore for an open
pit, Dew applications of the vacuum sampling
system are rapidly being made. One
of the most important of these is its adaptation
to underground sampling.
At Picacho there were 45,536 feet of
vertical holes drilled. There also were
drilled some 656 feet of hole from underground
setups, using one of the rock drills
from a Worthington WD-33 wagon drill
placed on a sc.rew-feed shell. Setups were
made using a tripod.
Operators have been quick to grasp the
importance of underground applications of
vacuum sampling.
Surface drilling was carried out successfully
by E. L. Jones and E. H. Page at the
Blossom mine near Ogilby, California. At
this property the equipment consisted of a
Worthington WD·83 Tower wagon drill,
vacuum sample collector, and 316-cubic
foot compressor similar to those used at
Picacho.
Another user of the outfit for surface
drilling was lack .McIver of Oatman, Ari­
""IlL Mciver drilled 16 test holes on the
Indian Springs mine near Kingman, An·
" .. IlL Test-pit checking proved the method
remarkably accurate and satisfactory. The
A Worthin,ton 521 drill operating at the
Fortuna mine. In the collar of the hole the
collector hood i. in place and to it i.
attached the .uction ho.. which cony.y.
, the cutting. and dual to the vacuum
.ample collector.
cost of operation was low. The total cost,
including purchase of equipment and operation
expense, was at least $35,'000 less
than would have prevailed if the work had
been done by standard underground methods.
,
A number of deep holes were drilled
horizontally at the old Fortuna mine 18
miles southeast of Yuma, Arizona. The
famous old Fortuna mine with its myriad
of faults in schist and other complex geological
features is a geologist's paradise.
The property produced roughly $2,500,000
some years ago and provided a handsome
profit to the stockholders. The ore was
cut off by two faults, one on the strike
of the vein and another on the dip, which
resulted finally in closing the mine. Th~
present operators have opened up the Suicide
Shaft and have encountered some ore
Lat. mod.l ..... pl. coll.ctor for
aurfac. a.e.
Which has paid for a portion of the d.
velopment work being done. The drill
holes were put in to compile geologiea1
data, and otherwise check the fonnationa.
Drilling conditions were adverse to the Nth
degree. The ground was heavy, fitchel'}',
and damp. However, drilling proved to be
far more economical than previous drift.
ing costs and supplied the necessary geological
information required for the solution
of the problem at hand.
The Burton Bros. (Clifford Burton and
Cecil Burton) of Rosamond, California, are
at present engaged in 8 program of drilling
and sampling at their several mines, utilising
the vacuum method of sampling. Work
has been started at the Ruth mine near
Trona, California, and is to be followed by
work at the Davenport and at the Tropico
mines.
The Ruth mine is still in the development
stage but treats, by the cyanide leaching
process, approximately 70 tons of gold ore
per day. The gold occurs in a quartz vein,
carrying iron oxides. The country rock
in the area is granite with intrusions of
monzonite porphyry. These intrusions Borne
times carry subsidiary quartz veins with
values in gold. The drilling qualities of
the ore may be described 88 medium hard.
The equipment used in drilling and
sampling underground at the ·Ruth mine
consists of Worthington Model·240 ham·
mer drills (air motor feed) and vacuum
sample collectors. Air is supplied by
Worthington full Diesel, 315-cubic foot.,
two--stage compressors.
Similar steel and bits are used 88 at Pi*
cacho (l\4·inch hollow-round steel with d&­
tachable cross bits) except that lengths ~
. provided for steel changes to meet underground
conditions. Lengths of rod now in
use include l'h feet, 2 \0 feet, 5 feet, and
10 feet. Attention is given to maintaining
a minimum number of' couplings in the
hole.
Holes may be drilled at any angle
through a full circle of 360 degrees. The
different angles require different technique,
both in drilling and in taking tht
sample.
When a horizontal hole is desired, the
hole may be drilled more easily by pointing
the hole up at a small angle. Underground,
for steep holes, it is sometim~
necessary to cut out head room for the
drill in \lrder to handle the rods.
Holes drilled from the surface also may
be at any angle provided the proper wagon~
drill mounting is used.
HE following procedure is used to se·
Tcure accurate samples. In ord~n&!7
rock a a-inch cross bit is used to start the
hole. The suction hose from the sample
collector is held at the face while starting
the hole, to catch all the dust and cuttings.,
When the hole is about 18 inches deep a
metal dust-hood, which holds the SUCtlOD
hose and catches the cuttings, is
in the hole. In the event the ground at
the collar is soft or very ravelly, a J.araer
bit is used to start the hole, in order to
penn~rtion of a 4-inch casing to
vide a good working collar.
P.., • • ,
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THE .MINING JOURNAL t ... SEPTEMBER 16,