Bisbee daily review., 1917-12-02

the returned tailing-water is an Mn.
Crane wood-lined pipe. The leak-il-
quor, which Is returped to the mead
of the precipitation system by lead
lined centrifugal pumps, is carried in
a Gin. cement-lined pipe. The cement
lining is about Is in. thick and the
coating is done at the Copper Queen
shop at Bisbee. The entire operation
OF the plant, consisting OF nltratl0n,
precipitation, cleaning, handing
scrap iron. drying and sacking cement
copper. pumping and general mainten-
ance, requires a force of eight men
and one foreman. The iron consumed
amounts to ~ pounds per pound of
copper precipitated. The theoretic
quantity required is 0.SS pounds iron
for each pound of copper, but there is
mechanical loss, and certain
amount of ferric sulphate still remains
in the solution after passing through
the pyrite filter. Every unit of ferric
iron calls for half as much metallic
iron in its conversion to ferrous SUI
plate in the precipitation boxes. The
free sulphuric acid also consumes iron.
Therefore the recovery of one pound
o: copper with an excess of only 62
pounds Of iron over the theoretical re-
Cuirements, in which is included the
mechanical loss as well as the loss
from Tree sulphuric acid in ne solu-
tons, show how important Il role is
performed ythe pyrite filter when it
10 ,1fl A-tr Al H.
water carries nearly pound for pound
of copper and ferric iron. Without
the pyrite filter this ferric iron alone
would dissolve a half pound of me-
tallic iron for each pound present as
ferric salt in the solution.
It has been pointed out that the pre-
cipitation in large round watts has been
shown to be more efficient than in
launders. In the new plant that will
be built to handle the solutions from
heap-leaching on a large scale when
treating the Sacramento Hill low
grade ore, such watts will entirely SUI
persede the launder-system. The same
system may be installed at the Burro
Mountain mine, the tentative plan be-
ms oiOWA lnt dCNOn-
panying sketch Gig. y. A further
improvement is proposed, in accord
ance with a design by Joseph Irving,
Jr., which consists in adapting the
Dorr mechanism to precipitating vat
AS will be seen in Fig. 3, the stirrer
is placed below the false bottom and
the solution is fed through a vertical
wooden conduit surrounding the spin
die of the machine, which may be a
solid OF perforated cylinder. The stir
rer serves to impart a movement to
the solution, causing the copper. as
fast as it is reduced by the scrap-iron
resting on the false bottom, to become
detached. AS the cement-copper set
ties it is swpt to a pocket in the bot
tom of the tank. from which il can be
drawn off at intervals.
Heap-Leaching The ordinary reac-
lions in the oxidation of sulphides of
iron and copper have long been util-
lied as a ready means for teaching
low-grade ores in which The copper
is present either wholly as a sulphide
or as mixture of sulphide and oxide.
Although the last word has not been
written on the subject, the principles
are quite well understood; neverthe-
less, the disappointment. partly be-
cause of the difficulties arising from
ferric sulphate in the solutions and
from lack of familiarity with the de-
tails of mana gement in teaching ore
heaps. Therefore the work done at
Bisbee is of great interest, since il
has established an economic line OF
treatment that will be employed both
at the Burro Mountain mine in New
Mexico and at Bisbee on a larger scale.
Indeed. the possibility of adapting the
method as a means for profitably eX-
tracing the copper from the 100000
tons of the lower-grade ore developed
in Sacramento Hill has been an i'm
portant factor in the plans for ben
officiating that unique deposit.
1t may be desirable to re-state the
reactions responsible for the solution
of copper in moistened ore-heaps, and
to point out that no inconsiderable
knerit in the system lies in the posi-
bility of recovering much of the cop
per that may happen to be present as
du OAiut. ne very lOW-STdut COppti-
sulphide bodies usually are found in
fairly welltdefined zones. either on
the borders OF higher concentrations
of ores, or on zones through dissem-
mated orebodies where oxidation has
been more rapid than the reactions
that determine enrichment. These two
cases are found in Sacramento Hill.
and liz each of them portion of the
copper has been converted into the OK
ide. CarbOnates of copper. however,
are practically absent. The reactions
on which the solution of the oxide de-
ponds may be represented by the &C
don o. cupric sulphate upon cupric
oxide, yielding basic copper sulphate.
Acid generated in the oxidation of
the sulphides will also directly attack
both cuprous and cupric oxides.
1t should be pointed out that the
danger of producing metallic copper
is always considerable and deserve at
tentiOn on the part of the superin-
tendent with a view to obviating as
far as possible the conditions favora-
Bile FOR such reactions. Metallic cop
per may result also from the action
of ferric sulphate upon cuprous sui
phide.
Mr.. Irving admits the possible form
alton of some metallic copper in the
lpaphinO Of tho ora-haan hut IL has