The Anaconda standard. [volume] (Anaconda, Mont.) 1889-1970, 1897-12-09

Z upper pulltNs
The dredge is equipped at the rea1
end with two spud timbers. ~ inches b,
! Is inches by 30 feet in size, and weigh
+ ing over 11.000 pounds. These are eacl
( fitted with a pointed steel wearing shoe
at the lower end and with the necessary
4 gearing for raising and lowering These
spuds are for moving the dredge for
ward or backward. being alternately
raised by means of hosting cylinders
of "A tons capacity and dropped after
! the dredge has been swung by the pngi-
neer in the pilot house through the ca
bles passed around the front corners
Of the boat to a lateral anchorage The
boat is thus walked ahead. While ex-
caNating. one of these SpuuS rests In
the gravel at the bottom and forms a
pivot around which the boat is swung
as the gravel is taken up. BY means OF
the suspensory cables carrying the
bucket ladder this ladder is lowered
about six inches. with each
swing of the dredge around
the anchored spud Thus with
the drag of the bucket a segment of
gravel inches deep and feet wide is
eXcavated. This lowering of the ladder
continues until the bedrock is reached.
The bedrock. if yielding. is torn loose
and brought up until barren of values.
Strong jets Of water are introduced
into the hopper in which the gravel has
been dumped by the buckets i'm passing
over the upper pulley. The mixed
gravel and water feed themselves by
gravity into a revolving screen or from
mel and additional water is INTRODUCED
This trommel is l. feet long. As inches
in diameter and inclined three inches 10
the foot. The perforations are one and
one-half inches in size. The larger
rocks are separated from the finer
gravel and sand and passed out Of the
lower end of the trommel into the
water at the side of the drcIge The
finer material drops into a second hop
per. which is swung below the water
level by chains. near the center of the
dredge. This hopper is reduced in size
and and continued in a 1J-inch suction
to the centrifugal pump. This pump
is of the Fred *. Prescott type and
discharges the pulp that has been
passed into the suction to the sluice
box located at the upper deck. 1t is
run at speed Of 80 revolutions and
has capacity of from 5000 to 5000
gallons per minute. In passing through
this centrifugal pump the gravel suffers
final disintegration of any clay or ce-
ment masses contained and effects
complete freeing of the gold. 9S per
cent of the originally contained gold be-
ing saved in the sluices, The dredge is
also equipped with a Dean pump Of
large capacity, which supplies the water
to the hopperS and trommel and 10y it
jets of clean water are introduced 10 the
bearings within the centrifugal pump
to free from them gravel and prevent
consequent heating.
There are two sluice boxes. The first
begins on the upper deck just back of
the pilot house and is 30 feet long, 80
inches wide and 40 inches deep. 1T dis
charges into a lower sluice box which
is Sc feet long, projected beyond the
dredge and suspended by cables from
an A-frame. These sluice boxes are of
steel and fitted with false bottom
of square steel plates separated some
three inches. so that the heavier gravel
and stones which have been freed af
all clinging gold do not pass over and
cause excessive wear to the rifle
boards The weight of this suspended
sluice box on the A-frame when carry
ing the discharge from the pump is
900 pounds. This sluice at the lower
end, where the failing are abandoned,
can be swung laterally by means Of
cables to deposit these where desired
To overcome the tipping that might be
occasioned by this lateral swinging the
dredge is supplied with two boxes. each
40 feet long, II feet wide and A. inches
deep. located lengthWise of the boat
under the lower deck. Water is pumped
into the opposite box when il is de-
sired To swing the sIuice literally and
overcome the tendency to tip the
dredge.
The Traction Drcdge.
The traction dredge on land mining
machine at Washington gulch has been
designed to work in ground that is un-
usually fiat and where but little water
is obtainable. 1t is owned and operated
by W. NJ. Johnston & Co, of Chicago,
who also designed the plant. The build
ers We're the Marion Steam Shovel COM
pany and the Gates Iron works. 1t
works dry gravel. and where the ma
chine cannot sufficiently clean the bed
rock this work is done by hand labor.
The entire plant is supported ON four
bogie trucks which move ON double
tracks, II feet apart laid ON the bed
rock. No jack arms, side braces OF
spuds are used. Steam is supplied by
one 80 horsepower boiler to a set of
dredging engines of the same capacity.
These perform the excavation, handle
the car run the washer and trommel
and move the plant forward when re-
quired. That part of the machinery
by which the eXeavating is accomplish
ed IS similar in design to that used for
such purposes on steam ShOVels The
boom is 40 feet long and carries a dip
per or shovel Ia cubic yards capacity,
and handles 20 cubic yards per hour
The water supply To this plant for all
purposes is 20 miners inches.
In this gulch the bedrock lies some 1G
feet below the surface. Above this is
the auriferouS gravel on which is a
considerable uNerburaen Of barren ma
tefial. This latter is first stripped of
and disposed of Al the side without
washing. The pay gravel is then taken
UP by the shovel and dumped into a
car at the other side of the plant which
runs an an incline. One end of this in
cline rests on a shoe set i'm solid ground
on the bank OF the cut and the other
terminates ON the roof OF the dredee
The car when filled, is hauled up by
cable operated by the engines and
dumped into hopper on top Of the
plant The gravel passes into Il washer
and trommel where complete disin-
tegratiau is effected and the coarse efa-
vel aud rocks passed out at the rear
end Of the plant. The finer gravel. sand,
gold and water pass through the per
formations Of the trummel into a slulcf
box originating Immediately below This
sluiee extends some distance behind fht.
plant. being carried rs suspensorv