El Paso herald. (El Paso, Tex.) 1901-1931, 1910-09-06
A Model Plant in Operation
at Dolores Mines a Good
Example Of Methods Used.

The cyanide process in the treatment
Of silver and gold ore in a silicious
gangue, a class of ores constituting the
bulk of the ores of the Sierra Madre
range of Mexico, has worked Il reTGtu-
ticn in the mining industry. For many
years in Mexico, silver and gold bear
ing ores have been treated either by
panama. gamatiOn, the patio process, or
in other cases Of roasting and teaching
with hyposulpnite of soda The remote
ness of many of the mines from smell
tiers, the absence Of railroads, and the
high cost OF transportation made 1t
necessary for the different mines to
adopt processes most suitable to treat
their ore at the mines.
During the past ten years a radical
change has taken place throughout
Mexico in the treatment Of silicious sill
yer bearing ores, and today most of the
mills are being changed TO cyanide
plants, using as rule fine grinding,
agitation, fntering through suitable me-
cnanical filters and precipitating either
with zinc shavings or zinc dust
One Cyanide Process.
a description of the cyanide prac-
tice at the Dolores mines, in the western
part of the state of Chihuahua, Mexico.
by ". H Paul, general manager, gives
the latest and most uptodate informa-
tion and is as follows:
1.-The ore from the receiving bins
from the mine is fed from ore bins into
% stamps, crushing through battery
screens Of eight mesh. The product then
flows TO a revolving King screen, using
a 2O-mesn screen. The overflow passes
through three Bryan mills, which grind
the ore through 70-mesh screen; the
underflow passes over four whitley
tables and two vanners; the product Of
each Whitley and vanner is sized, using
hydraulic sizers and cone clessifiers.
The product from the Bryan Mills also
unites with this same flow and passes
over the concentrating table. The con-
centrates are automatically removed
and conveyed to a drying room, where
they are dried and sacked The tails
from the table pass to three Bayl1s
classifiers. where the sands are re-
moved automatically and discharged into
four tube mills, while the slime passes
into the cyanide plant. These tube mills
are l6 feet long and three and han
feet in diameter and are charged with
about four tons of flint pebbles. From
the tube mills the product is returned
over the tables and back through the
cIassifiers. The slime from the classi-
fier flows direct into the cyanide plant.
Makeup of the Plant.
1.-The cyanide plant consists of seven
tanks, % inches in diameter, Is feet in
depth These tanks are equipped with
mechanical agiJators and centrifugal
pumps for circulating the solution TWO
tanks are used for filling, two for agi-
tating, and two for settling and decant-
ing, and one is a storage tank for the
Buffers filter.
In filling, two tanks are filled at
time. this requiring as rule about "a
hours These two tanks will hold APP
proximateIy 80 tons After filing
the tanks are allowed TO settle and the
mill solution decanted. This requires
about four hours.
"A strong solution of cyanide is added
to these tanks and sufficient cyanide of
potassium put in to bring the strength
of the solution to from o-o4 percent to
COS percent. The tank is then agl-
tsted by mechanical agitators and the
centrifugal pump for "A hours. 1t IS
then transferred to another tank and as
much Of the strong solution decanted as
the time of operation viii allow. From
this tank 1t is transferred 10 the shines
storage tank of the Buffers litter.
"a dilute solution of cyanide, free
from gold and silver values, is run into
toe Buffers press and the shines thor
orgblv washed for an hour or an nour
and a half to wash out all soluble val
mes. Afterwa-d this solution Is DIS
charged and a wash Of water given 10
the cake to eliminate the final traces OF
value and the cyanide as far as possible.
The discharged solution is pumped into
a series of settling boxes so as TO
clarity If as much as possible, and then
allowed to flow through the zinc boxes.
TIE zinc house consists of six rows or
zinc boxes, two containing six com
,,artments and four containing nine
commandments These are packed with
zinc shavings, and the solution passing
down. precipitates the gold and the Sill
yer.
Two solutions Used.
Two classes of solutions are used-a
strong and a weak solution. The weak