Elk City mining news. (Elk City, Idaho) 1903-1913, 1905-06-24
CONTINUED FROM LAST WEEK. ]


Punched sheet iron makes a better
screen for the boxes than wire. The
wire rusts more quickly and breaks down
under the weight it has to support: The
screen should always be a flat sheet
without any vertical sides. A tray pro-
tects the close packing of the zinc, for
it leaves a space of about half an inch |
around the sides where the solution can |
come up and form channels.
Within recent years there has been a
tendency to change from the old style
of box and use what is known as the
individual or single compartment type.
These are boxes with single compart-
ment arranged for up flow, and are used
in series, the number depending on the
size. Some are connected together by
single pipe fittings, while others are
arranged to overflow into the lower box.
Small tanks from to feet in diam
eter and from to 5 feet high, have
been used for this purpose with a great
deal of success. The cylindrical form
is easier to pack and the tendency for
the solution to channel is much reduced.
They are more convenient to handle, less
liable to leak, more portable, and much
cheaper than the rectangular, multi
pie compartment box. 1t is quite likely
that this form will supersede the old
boxes in the cource of time. The
number of boxes in a plant depends on
the amount of solution handled and the
way the gold precipitates. Separate
boxes are used for handling the weak
and strong solutions. The boxes should
always be covered and a strong lock put
on. Launders are sometimes attached
to the sides to facilitate the cleaning up.
They are handy and reduce the mechan-
ical losses in handling the shines.
Below the precipitating boxes are the
sumps. Two are generally used, one
for weak and one for strong solution.
In very large plant there are many
more. They are always placed at the
lowest part of the mill. Sometimes
where it is difficult to get sufficient
grade the sumps are set into excava-
lions made in the ground and the earth
filled in around them. This should never
be done. If it is necessary to set them
under ground, a space should be left
around them so they can be examined.
The solution tanks are always placed
above the level of the top of the leach
ing tanks, and are generally the highest
tanks in the mill. Two tanks are used,
weak and strong.
In a typical crushing mill there would
be no solution tanks, but two extra
sumps are installed instead. A water
tank should be provided. This should
be elevated above the teaching tanks.
Sometimes a small tank is used for dis
solving the solid cyanide, but it is not
necessary. The best way is to put the
cyanide into perforated box suspended
under the pipe that delivers the solution.
' When the solution is pumped in the cy-
t anide rapidly dissolves.
One of the most important features
about a cyanide plant is the pipe system
This must be designed strictly in accor-
dance with the treatment the ore is to be
S subjected to. The essential feature Of
S good system is simplicity. A compli
Gated system, while it may possess Ger
tain good points is apt to confuse the
solution man and cause him to run tt
waste valuable solution.
i All metal about the plant should bc
:, iron, as it will resist the corroding ac
|. ton of the solutions better than an.
= other metal. Brass or copper SHOULD
never be used, if it can be helped. Thu
i best value for all round use is the cheal
/ cast iron plug valve. These valves ar
ii not as easy to manipulate as the NOR
l. expensive gate valves, but they do tn
6 work and seem to have the preference
The equipment and design of tn
- cleanup room needs careful attention
The mechanical losses from the handl
'e ing of the gold shines amount to grea
/. deal, and though it is not possible t
~ eliminate them altogether, they may b
reduced to nominal amount by takin
" the proper precautions. The CLEANUP
Re room should adjoin the precipitatin
K department, to avoid transporting tn
De shines any great distance. Both shout
- have a concrete floor sioping to drai
pipe that discharges into a stump. l
90 the United States the precipitate
n usually refined by the acid process. Tn
acid refining is conducted in tank pr