Elk City mining news. (Elk City, Idaho) 1903-1913, 1905-06-10

tain amount of water, the particles will
be free to rearrange themselves, and
will separate out in the order of their
specific GRANTEES. If all of the pulp is
taken from a wet crushing mill and
discharged into tank the slime and
sands will separate and arrange them
selves in strata.
Such material cannot be treated. In
all wet crushing mills it is, therefore,
necessary to put in hydraulic classifiers
and separate the sands and shines and
treat them separately. The cone clas-
sifers, first introduced in the Black
Hills, represent the latest improvement
in this line. They are cheap, very sim
pie and work admirably. The pulp is
taken from the plates or concentrators
and discharged into the funnel of the
classifier. The heavy sands sink down
through rising cnlumn of water and
flow out at the bottom. The slime is
carried up by the currant and flows over
at the top, and is conveyed to slime
treatment tanks or else run to waste.
The sands discharged from the classi-
fer are taken to the automatic distribr
utors over the teaching tanks. These
revolve slowly under the action of the
current and spread the sands evenly
about the tank. 1t usually happens that
some slime escapes the classifiers and is
carried into the tank. To get rid of it,
it is necessary to have the tank full of
water while it is filling. The shines are
then held in suspension and are carried
away by the overflow and caught in a
circular launder built around the tank.
The latest idea is to drain off the water
through the bottom as fast as it runs
in and keep the surface of the sands as
dry as possible. This makes it possible
to mix in some slime without danger of
a separation of the two classes of ma
terial.
DISSOLvING THE GOLD AND SILVER. -
A mill treating dry ore or tailings should
be arranged differently from one treat
ing wet material The principal differ
ence is in the arrangement of the pipe
system and the stump and solution tanks.
In dry mill there are two solution
tanks and the first solution run in is
delivered below the filter bottom and is
allowed to rise up through the ore. A
wet mill has no solution tanks, but a
double pump system instead, and the
solution is pumped on to the surface of
the ore and allowed to percolate down.
After the tank is filled with ore the
cyanide solution is turned in and after
becoming saturated it is allowed to
stand for several hours and soak.
The precise method of treatment s
variable, and the details-such as the
strength and quantity of solution to use,
the time of contact, and the order Of
applying the different washes and draw
ing them off-have to be worked out by
} experiments. The usual practice is tt
apply first a strong solution and follow
with weak one of half the strength Of
the first one; winding up with a water
| wash, after which the tank is discharged
| and fresh charge put in.
PRECIPITATION. The solution with
drawn from the teaching tanks contains
: the dissolved gold and silver. This may
be recovered by any of the following
: methods: Q) Precipitation on zin'
shavings; (2) precipitation by zinc dust
/ (3) precipitation by charcoal; (4) cleo
trolysis.
: Only the first method is used to an.
r extent. 1t consists in passing the solu
] ton through box filled with zinc shaw
2 ings. AS the solution runs through, tn
t zinc dissolves and the gold and silve
e are precipitated as fine powder. Fresl
3 zinc is added once every twenty-fou
: hours. The solution as it comes iron
n the solution tanks passes to the gol
S tanks. These are simply storage tanks
e and though they are not absolutely nee
Y essary, it is convenient to have them
=, They serve to settle any sands whic
e may have found their way through hole
n in the filter cloth, and also maintain a
even pressure on the solution running
: through the precipitating boxes. TIL
e best way to draw the solution fror
:; these tanks is by means of a decanta
ton pipe, or flexible hose attached t
r an outlet in the bottom of the tank, an
e the inlet so fastened to float that it
f kept about an inch under the surface O
. the solution.
o ITO BE CoNTINUED.)