Little Falls herald. [volume] (Little Falls, Morrison County, Minn.) 1889-1950, 1904-04-29
THE CYANIDE PROC
Something About the
Latest Method Of
Gold EXTRACTING.

Latest Method of
Gold Extracting.
As there seems to be considerable
interest in some parts of Morrison
county In the alleged gold discoveries,
q description of the latest process for
the extraction of gold from ore may
be of interest. This is known as the
cyanide amalgamatlon process and
its use has developed within the last
ten years.
The process of tie extraction of
values from various mineral produc-
ting rock called ore is known as
reduction or 'ore dreessing.' Re-
duction is generally accomplished by
one Of three well-known methods,
namely, smelling. chemical dissolu-
tion and mercurial amalgamation.
The process of smelling is an old one.
It ie. however. the most expensive
method on account of the large
amount of full necessary in obtaining
degree IF heat enough to melt the
ores, and also on account of the cost
of procuring auxing materials, such
as iron, lime and copper. The loca-
ton Of smelling plant is determined
by the proximity Of fuel and fuxing
materials, therefore necessitating
heavy transportation charges on the
ore from the mines to the smelter
AS is we'll known, there are many
low grades Of ore that will not permit
of smelling cost.
The amalgamation process is the
most simple. However. only ore
carrying free gold can be treated by
this process.
The chemical process is compare:
lively new, and has made wonderful
strides within the past ten years.
This process is now generally used on
all ores that cannot be treated by
amalgamation, excluding, Of course,
ores Containing chemical combination.
which prohibit economical chemical
separation.
The following is a description of
the process as used in a 6O-stamp
plant at Deadwood, S. D., at cost
to the plant owners OF 80 cents ION;
The ore, after having been dumped
into the bins from automatic rail.
road ore cars, at the upper part or
the mill, passes into crusher which
has a capacity of over Az tons per
hour. The product Issuing from the
same varies in size from that OF an
ordinary sand up to rocks having an
extreme dimension Of about two
inches. This ore drops from the crush
or to the belt conveyor, ~ inches
wide. This is moved from one bin to
another, the belt going through this
machine in such way that no ad-
justment of the belt is necessary In
changing the machine from one bin
to another. The ore Is drawn by
gravity to the automatic feeder and
passes into the mcrtars under the
stamps, which is 60 in number,
weighing 1850 pounds each and
dropping SO times per minute from
height Of seven inches. Five stamps
drop into each mortar. The mortars
are Of the narrow type low dip double
discharge and the stamp duty crush
ing 16-mesh is five tons per "a hours
giving the plant capacity of 300
tons per day. About two pounds OF
lime per ton of ore is added to the
crushed rock in the feeder just above
the stamps. This aids the solution in
the decomposition of the ore. The
ore is crushed between cast iron shoes
and dies while the cyanide solution
is passed through the mortar after
which the pulp consisting OF the solu-
ton and finely pulverized ore passes
through the 16-mesh screens on both
sides of the mortars and is conveyed
through launders to stump boxes one
TO each 20 stamps From these sumps
the pulp is then forced through spiral
pumps to the conical classi6ers.
These cones are six feet in diameter
across the top and about six feet deep.
The pump Is run into these cones
slowly and carefully so that the sand
Immediately drops to the bottom
while the veN fine pulverized ore
known as shines which are very
light, float over the top of the cones
into collars and is thence conveyed
through launders to the slime tanks.
At the bottom of each cone is q
valve, which is turned on sufficient
to allow the sands to pass through just
fast enough to keep the cones full so
as to allow an overflow Of solution
with the Shines The pulp runs in a
steady stream from the pumps to the
cones, so that this is easily ADJUST
able. The sands pass thence to the
sand tanks.
The sand tanks are 40 feet in
diameter and six feet in depth, each
having capacity of $50 tons. The
pulp that enters the tank consists OF
about one half sand and one half so
luton. The ore is charged with about
three parts Of solution to one Of rock
in the mortars, but large part OF
the solution is taken off in the conf
cal classifsrs. ---- -
After a tank is filled which takes
about one days time. more cyanide
solution is forced into the sands from
the bottom of the tanks and is al
lowed to percolate up through thu
sands. The percolation is aided quite
materially by the use of the pneuma
tic process, which causes the circula
ton of air through the sand. TIT
solution ia thus allowed to act on thu
pulp in the sand tanks for about foul
days, when wash water Is thei
brought into the charge and the wash
ing continued until there remain
only .02 to .03 of per cent cyanid'
in the wash water. All of this solu
tion then goes into the zinc box TO-