Arizona republican., 1922-05-17

unit consists of three crusherS, which
are interchangeable in every respect.
The first is set to crush to inch cubes.
The material so crushed is elevated
and screened; the undersize by
passes the remaining two crushers,
which are set in parellel. The over
size passes to these two. crushers
which are set to crush to the desired
size. The entire product is fed to a
system of belt conveyors, which lead
through a sampling plant to the
teaching watts, which furnish the only
storage for the crushed ore. The
disk crushers are run by direct con-
nected 75-hp. alternating current
motors at 400 rpm. The pinion
shaft is long, perPitting the motors
to be set in separate room, thus
being protected from dust.
Method of Leaching
The teaching tanks, IS 1T. (26.S NO.
square and II fl. in. (5. 2S NO. deep
inside, are built of reinforced con-
crete with wooden bottoms. These
have a capacity of 5000 e. each OF
crushed ore. The falls are 9l9 IN.
CAL cm) thick and are strength
ened outside by concrete buttresses.
The bottom is OF by Sin. (7.6 by
20. g cm.) Oregon pine laid edgewise,
and Is supported by concrete foun-
dations. The sides and launders OF
the tanks are lined with S-lb. (3.6 kg.)
lead and the bottom with Glib. 4-per
cent. antimonial lead. The filter bot
tom is laid over the lead bottom and
consists of by 12-in. (12,7 by 80. 4
cm.) ioists on edge laid on l6-in.
| (40. 6 en- } centers, covered with 2-ln.
ship-lap planks that are bored with
* lin. g.. 5 mm.) holes on 2-in. t5oS
mm.) centers countersunk from be-
low. Under the center of the filter
bottom, and at right angles to the
wooden floor joists, there Is q dis
| tributing launder 1T. Ill NO. wide
by 2 IT. . in. CO.'S m.) deep, set in the
| floor through which the solution en-
| tiers and from which it is distributed
under the filter bottom. The lead
| lining on the sides OF the tanks is
protected from abrasion by a COW
ering of 2-in. planks held in place by
6 by Sin. 1872 by 20.3 cm.) vertical
posts clamped at the bottom and top
At the top and sides of each leach
ing tank are two overflow launders
extending the length of the tank, one
end being connected with the suction
of a circulating pump. The charging
is done by means of a machine es-
peciaIly designed for this plant, and
known as the spreader bridge. II
consists of a travelling bridge OF
structural steel which spans the
tknas and travels, as desired, length
wise with the row. The bridge sup
ports a 2S-in. (71.1 cm.) belt con-
yeyor. which receives the crushed
ore from the belt on the central
structure. A tripper on this belt
spreads the ore in the teaching tanks.
At the present time the tanks are
charged by filling to the top Of the
tank at one side, allowing the ore
to assume its natural slope, or about
as degrees, and then continuing at
one side and discharging the ore at
the top of the slope, allowing the
coarser material to run to the bot
tom and the finer to remain some-
what higher up, thus giving o. rough
classification. The bridge is moved
slowly forward as the filling of the
tank progresses. This plan was sug-
gested by the engineers of the Chile
Copper company, who have obtained
the best results through this method
of filling.
The crushed ore is leached from
six to eight days by a counter cur
rent system and upward percolation,
using dilute sulfuric acid as the
principal solvent of the oxidized cop
per minerals.
The solution In each tank is cir
culated by two 15-in. (3S. / cm.) ver-
teal centrifugal pumps of $500 gal.
C3,24S ID per min. capacity each;
These are driven by direct-connected
40-hp vertical motors. The head
against which the pumps work Is rs
1t. (S.5m.) which is virtually equiNa-
lent to the friction head of the solu-
tion passing through the ore. me
discharge from one of these pumps Is
provided with a bypass which per-
mits a portion of the solution to De
advanced to the next tank. Both
pumps are throttled to give a cir
culation of about 1000 to 5000 gal.
per min. through the ore. or TINS
amount about 1000 gal. (3lS5 ID
called the solution advance, is con-
tinuously passing through from tank
to tank. The high-aci solution (o
per cent free sulfuric acid) coming
from either or both the tank house
and the soution storage, and going on
the Oldest ore is called the ''acid ad-
vance" The nearly neutral solu-
ton coming off the newest charge
and going to the reduction towers is
known as the neutral advance.
Removal of TaiIings
After a charge has been washed
ana u1dlleu, IilG ldlllllSS al 2 lClAioN SN
| from the tank by means of a Hulett
| unloader. The machine was furnished
| by the Wellman -Seaver- Morgan Co,
! and is similar to unloaders used on
| the Great Lakes for unloading iron
ore from boats. A heavy steel bridge
! on trucks spans the teaching tanks
and travels their entire length. On
| this bridge travels a trolley carrying
| a walking beam, bucket leg, and buc-
| ket of IL r. capacity. The unloader
! has a rated capacity of 500 T. per
! hr. and viii generally eXcavate a
tank of tailings in 10 to IL hours.
An eng ineer and an oiler are re-
quired to operate it. A description
OF this machine has been written by
Franklin Moeller, engineer for the
Wellman Seaver- Morgan company.
| Two eight-car trains are released
from the mine service at 4:30 p. m.
for the transportation of tailings.
Twenty one to twenty-three train
loads of eight cars each are re-
| quired to excavate a tank. The tall
/ ings are taken to a dumping ground
located about mile from the plant.
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