The indicator., 1897-06-26


~ the study and practice of concentrai
Ing these sulphidps are growing very
last and with very satisfactory results.
Almost all mills have some system of
concentration, either below the plates
| or directly below the crushing machin-
cry.
The writer has had some experience
in the telluridcs and sulphidcs of Boul-
| der county and Cripple Creek, the
collaborating sulphidcs of Summit and
Gilpin counties. and the gold. silver.
copper and lead-bearing sulphidos of
the San Juan, and has had practical
| experience with many kinds of bump
ing tables, shaking tables. F'rue van
lers doth smooth and corrugatedD.
Woodbury. vanners, Triumph vanners,
Mcneil vanncrs, Lrrig vnnners, the Og-
den table. and jigs of several varieties
| and circular revolving buddies. find
that in nearly all the mills that | have
seen there is not enough Importance
given to frequent and perfect sizing of
the product before 1t goes to the con
cen'rnting machines and also n dispo-
sitlon TO pulvcriHc the ores far too fine,
TO make n close saving. as in the ordi-
| nary stamp mill | cite an instance
where, in n mill of which had charge
| had been crushing with stamps
'h''h-h IL -Hi'Sll DIlltIA S''It'u
and amnl-amating. our loss per ton
twenty and then to stxtcen-mcsh. put
in two hydraulic sizcrs. and the loss
| never exceeded ~ and was frequent
~ less than twenty-five cents per ton,
on the same or" as run through the
iortN-m"Sh screen. This ore was an
IRON sulphidc carrying n small pcrc?ut-
age of zinc. We saved by conccntra-
tion about all the gold and silver that
would not amnlgamatc. our product
always had less than eight per cent.
zine and about forty per cent. iron in
1t; the smcllerS gave us rates as fol
iows-ten per cent. silica and eight per
cent. zinc WIS the neutral basis: Smclt-
ing charges. So per ton. and also iif-
teen cents per unit for silica in excess
of ten per cent, with rebate of fiji
teen cents per unit for iron in excess of
silica. and charges of fifty cents per
unit for zinc in excess of eight per
cent. Ours being II clean product. we
were paid fifteen cents per unit for
thirty units of iron. which amounted
10 $50, which. deducted from SO. left
total smelling charges of LOO per ton
We could mine and mill, with our ca
pacity tlirty-fivc tons daily. ore that
| contained only $3.50 per ton in gold
milling this ore did not exceed sixty
cents per ton with steam power. The
mel Dill amounted to thirty cents per
ton of ore milled.
Another instance, where we were
milling an ore contninin. five per cent.
lead. ten per cent. zine. and seven per
cent. copper and iron. all in sulphidcs:
We crushed, first with II Blake crush
er To about one inch in diameter, then
passed through one set of 1iX3O-inch
Cornish rolls. crushing to siX-mcsl fine.
All ore that did not pass the first six
mesh revolving screen came back to
the rolls again, then was carried by
elevators to the revolving trommels or
screens; first siN-meSh screen delivered
the screened product to jigs with four
mesh screens: the next sizing screen
was ten-mesh, which delivered its prod
net 10 jigs with cight-mcsh screens:
next sizing screen WIS siXtccn-mcsh.
which delivered its product to jigs
with twelve-mesh screens: then all
material finer than sixtcen-mesh
went to hydraulic Sizers. making one
class twenty-mesh and one class thirty
mesh fine. which We're sent TO separate
1igs. and all material finer than thirty
mesh was classe1 as shines and sent to
circular revolving bubbles. where the
mineral remaining in the pulp WIS
about al taken out eighty per cent
of which would pass lOO-mesh assay
crs' sieve. The taiings were then al
lowed to run AWAY. In this case the
maximum loss was less than 81 per
ton. and generally about fifty cents.
The product contained less than eight
per cent. silica and less than eight per
cent. zinc. We We're pnid for all the
gold. silver and lead in the ore and
given free treatment by the smclters
The iigs were ordinary ihree-compart-
ment llartz jigs. with slight modiiica-
tons, running very much faster than
the old style of working. ana each JIG
handled about sixteen tons of pulp per
twenty four hours making all the prod
uct through the screens. The bliddles
or sinners We're circular revolving
tables, twenty feet diameter with bed
of best Portland cement. revolving
once per minute. The pulp and clear
water We're introduced to the machines
somewhat differently from the usual
practice. The buddle made n finished
and Il half-tinishcd, or middling prod
uct, The middinss were discharged
into the boot of Il small belt and bucket
elevator which raised it up TO the feed
box and sent ii again over the huddlc
by TINS process there WIS scarcely any
loss of shines and II clean product al
ways obtained. All the concrntrntors
should automatically discharge the fin
ishcd product into one large tank. iii
vidcd by n partition in the middle and
not over two and one-half feet deep.
so that water could be drawn off and
the product shoveled onto II draining
floor while the other one is receiving
the product from the machines. Where
there is no shortage or clear water Il
continuous DISCHARGE from ihn iips ,nuy
he made by leaving the jig gates partly
open: and in eases where there is a
shortage of clear water the excess
clear water may be raised from the
product bin either by elevators or
pump and used again in the batteries
or rolls. and by putting in simple de
vice to separate the clear water from
the tailings ut least fifty per cent. of
the tail water from tine ilgs and bud
dies may be utilized over and over.
The hydraulic STEERS We're conicaI-
shaped. with point down, All pulp and
water passing We're compelled TO go to
the bottom and there separated.
where the coarse ore passed out and
the overflow going through another hy-
lraulic siZcr. the coarse ore passing
ont mt the bottom and the shines over.
flowing and going to the slime ma
chimes. | would consider no hydraulic
siZcr n good one that did not have II
partition from the top to very near the
bottom. thus causing every particle of
pulp and water TO pass under the par
tition or cone. causing II complete
submersion of all metallic particles.
have seen n valuable product building
up like foam on top of an open sizer,
which came in contact with the air
and would not sink again. consequent
ly flowed Off with the surplus and tail