Elk City mining news. (Elk City, Idaho) 1903-1913, 1905-06-17
CONTINUED FROM LAST WEEK. ]

by means OF paine DOaruS, IL is cduSeu
to flow through the zinc. Here the gold
is percipitated In plants where gold
tanks are not used the pipes carry the
solution direct from the teaching tanks
to the boxes. The solution, freed from
its gold, passes to the sumps. In wet
crushing mill the solution is standard
lied, i. e., brought back to its original
strength, in the sumps, and is then
pumped back into the teaching tanks.
In a dry crushing plant-and by dry
crushing plant is meant any plant treat
ing material that was dry or nearly dry
the solution passes from the sumps
to the solution tanks, which are elevated
above the teaching tanks, is standard
lied here and then comes back to the
teaching tanks. All of the solution in
the plant is saved and used over and
over again. Occasionally the solution
may become foul and very weak in
cyanide, in which case it may be run to
waste.
REFINING. In the United States the
precipitate is usually refined by the acid
process. The precipitate taken from
the zinc boxes contains in addition to
the gold and silver, zinc, lead, copper,
and other metals. This material is put
into a tank, and acid, either sulphuric
or hydrochloric, is added. The acid
treatment is kept up for some time
until the base metals are dissolved and
the bullion is quite pure. 1t is then
washed with hot water by decantation
and then filter pressed or placed on a
filter to get rid of the excess of water.
The bullion is then dried in pans, after
which the cake is broken up, f1uxed,
melted down in a crucible, and the bar
made ready for shipment.
ARRANGEMENT OF THE PLANT. In
selecting a site for a cyanide plant it is
of greatest Importance to choose one
with sufficient grade to permit of the
handling of the ore and solution by
gravity. This of course is not always
possible, so the tanks will have to be
raised up on wooden structures. The
foundations for these should always be
built of concrete or masonry, preferable
in the form of long walls. The initia
cost of these is much greater than where
the wood is used, but they generally
prove cheaper in the end. A tank on {
week foundation is apt to move and ser
ious leaks may occur in which the value
of the solution lost will greatly exceed
the cost of the most substantial masonry
work.
If wooden stills are used, care must b.
taken to see that they are well set ant
are not placed where they will rot easily
Cyanide plants may vary greatly il
their appearance, but the underlying
principals which govern their construc
ton are the same. The teaching tank
are usually large and comparativel.
shallow. The height depends on tn
character of the ore. If the material t.
be leached is sandy and permits the so
luton to flow through it rapidly, it ma.
be as much as eight feet, while if it
Shiny and retards the flow, it may b
only Is inches. 1t is not advisable t
use tanks with a greater height thai
eight feet, for the reason that the or
on the bottom will not yield high ex
traction because of the failure of tn
oxygen to reach it. The tanks are us
ually made from five to six feet hig
and experience has shown that tanks o
this size give the best results in bot
percolation and extraction.
Before ordering teaching tanks tn
ore should be examined and tank sc
lected in conformity with its character
The side of tank should always b
straight. without any batter, and tn
hoops constructed of round iron, as thi
form is better able to withstand tn
corroding action of the cyanide solution
than any other kind. The hoops hav
only small surface in contact with tn
wood, and they dry quickly and may b
kept covered with protective paint.
The number of teaching tanks in tn
plant depends on the time OF, treatmen
The time of treatment is reckoned frol
the time the ore enters the tank unit
it is sluiced out and the tank is read
for fresh charge. A sufficient numb'
of tanks should be provided so that OF
can be discharged every day. If II
/, ore requires a six days treatment the
six tanks should be provided. The C
pacity of the plant refers TO the amour
&c o,.o +,.aa+a1 ova,-xr d hOr1rS If