Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1940-01-13

dumped on waste dumps just out
side the portals. Crosscuts and
stems were untimbered and only
! driven big enough for men to work
/ in them. Only rubber-tired wheel
barrows were used in these coyote
holes water liner was used in the
the drilling of the holes which were
then from three TO three and
half feet long; horizontal wedge
rounds consisting of twelve holes
were used. One shift would muck
| the previous shifts round, drill.
and blast going off shift Three men
were employed in each face. a drill
Ter and two muckers. all the tram
ming being done by the muckers.
Electric lights were strung in the
coyote holes; rubber hoses supplied
air and water to the drill Blast
| ing was done with forty percent
dynamite, using electric delay caps.
To clear the holes of powder fumes
compressed air was allowed TO flow
against the face for an hour or so
after blasting. Pressure tanks were
to supply the liner with water. In
! gersoll-Rand detachable bits were
used, being detachable in the quarry
blacksmith shop. A coyote hole
would be completed in a week to
two weeks. depending upon the
size
On completion of the hole, the
loading began Immediately In some
holes both black powder and dy-
Mantle were used, while in others
only dynamite was used The explo-
sive was loaded in pockets twenty
feet apart, the amount of explosive
in each pocket depending upon the
amount of ground to be pulled by
that pocket. All the pockets were
filled in with the muck as they
were loaded that had been previous
ly taken out of the coyote hole. No
powder was placed in the stem,
which was entirely filled with
muck. Two strings of Primacord.
used in decorating the charge, were
unrolled from the portal to each
pocket and wrapped around the
several boxes of dynamite or cans
of powder. The two continuous
strips connecting all the pockets
gave very little chance for a miss
fire. The ends of the Primacord
were then set off by electric caps.
Seven thousand and twenty-five
pounds of powder was the mini
mum charge set off. yielding 49,
057 cubic yards of rock. The maxi
mum charge of explosive in one
coyote hole, Coyote Of, was g.
$50 pounds of black powder and
LOO pounds of 40 percent dyna-
mite, yielding 70.O1S cubic yards
of rock. One would think that such
a charge would produce a violent
explosion, but when backfilling was
properly done and no unforeseen ac-
idents occurred the blast was very
mild. The ground was lifted slight
ly, the bottom being pushed out a
few yards, and the whole mass then
gently settled. However, the tremor
produced could be felt as far as
Harlem
Driving of the coyote holes was
directed by the engineers, who
would survey the progress made
by the miners each day, and plot
the data on a map. Each coyote
hole was mapped separately on CO.
ordinate paper When the coyote
near completion the engineer would
compute the yardage that the blast
was to break by cross sectioning
tn ground above and in front of the
coyote. The ground above the coy
ote would vary from about eighty
to one hundred and ten feet, and
that directly in front was around
fifty feet, rising at various angles
to the top. Theoretically, one pound
of powder was used for each yard
of stone to be broken. The top of
the quarry was surveyed and cross
sectioned by a grid system, and
from this the total yardage broken
was usually greater than calculated.
When the blast was completed
railroad tracks were moved to the
edge of the muck pile and a SHOW
ell began to load the cars. Sixty per
cent of the rock blasted resulted in
waste. Sub-foremen located at each
shovel directed the loading of the
pay rock and the waste. The sub
foremen were checked by inspectors
who had to pass all the pay rock.
Four shovels were in operation as
continuously as possible; one SHOW
ell was always kept in reserve for