The Salt Lake tribune. [volume] (Salt Lake City, Utah) 1890-current, 1907-05-06
MoNTANA-ToNoPAH MILL.
Interesting Report of F. L. Bosqui Up
OH the Needs of This Ore.

In 1905 the Montana Tonopah Mining
company forwarded trial shipments of orc
10 various mctallurgical establishments
In California and other Western States
with the view of arriving at the most
suitable method OF treatment OF Tono-
pah ore. which Is a dry auriferous- silver
orc. The results were not very satisfac-
tory so Francis l.. Bosqui, the we'll
| known cyanide expert Of San Francisco.
was called upon for advice, According TO
a recent statement issued by the COM
pany' Mr., Bosqui has reported as fol-
lows, says the Engineering and Mining
/ Journal:
In the early part OF 1906 j directed
series OF milling and cyaniding tests on
| n carload OF average milling ore from the
Montana Tonopah mine. These tests
! were made in san Francisco. and were
! completed at the time of the fire: but
! all records of this work were destroyed.
| The average extraction obtained by con-
! centration and cyaniding was 81 per cent,
/ Later in the year / supervised another
! series OF tests In Denver on carload OF
! similar ore, and confirmed The results OBJ
! tanned In the San Francisco test, OBJ
J tanning the same average extraction, and.
by renewing. solutions during agitation
In the cyanide work. obtained recovery
OF over 30 per cent, | doubt, however,
II the latter result could be attained in
actual milling without prohibitive cost
per ton, and consider that an extraction
ranging between SO per cent and 90 per
cent is the best that can reasonably be
expected from the mill.
"Dn the basis of these experiments a
40-stamp mill was designed in the fail OF
the year, and the orders for machinery
and supplies placed. The process decided
ring in series of Gates gyratory crush
ers, using one No, and two No, ma
chimes. The ore is elevated 10 the mill
bins on belt conyeyer. whence 1t passes
TO eight batteries of five stamps each.
provided with l2-mesh wire screens II
Is expected that the service of these
IN twenty-four hours; The product from
these stamps Is classified, the coarse ma
lorial passing to eight Wilney tables,
Dorr classifiers which precede the tube
mills. The tails from the Wineys also
go TO these classihers, whence the coarse
product goes to the tube mills for re-
grinding. II Is proposed TO grind to $50
mesh IN these mills OF which there arc
two. each 5xc2 feet. The reeround prod
uct from the mills joins the overflow from
the Dorr machines. and the whole product
Then passes TO TWO large cone classi
flcrs.
The underhow from these cones goes
to sixteen true vanners anu the over
flow joins the stream of tailings from
the vanncrs and runs TO the settling
tanks in the cyanide plant. From the
settlers the pulp Is taken as required TO
the agitetors, Of which there are six os
the IendryN type. After agitation in a
cyanide solution the pulp is drawn off to
q large reservoir where it is stored for
nltcring by means of the Buffers vacuum
liltcrns process. The gold and silver
bearing solutions recovered on zinc-dust
In the Merrill precipitation press. which
hau been SO successfully used at the
Homcstake mine. All lumber and cquip~
ment for the mill were promptly dciV-
cred, but the work has been seriously de-
laycd by several consecutive weeks or bad
weather, during which time work had TO
he suspended. Lately, however good
progress has boen made, Under favora-
bic conditions this mill would have been
finished about April 10. but it is doubt.
ful now II 1t will be ready much before
June i.
This mill will he thoroughly modern
In all respects and embody the latest
practice both IN milling and cyanidlng,
Owing TO uncertain labor conditions. al
Nevada fields. 1t was difficult TO estimate
the total cost Of labor on the mill More
over the working drawings were not COM
petcd until some time after the order for !
the bulk OF the machinery had been
placed. and consequently 1t was inlpossi- |
bic to submit an accurate estimate Of the |
cost OF the mill. which would include the !
building proper, shaftinS. betting. piping. |
etc, and many other details which de-
yeloped in the course Of working UP the
drawings The first provisional estimate |
placed The probable cost a; $50 600 but |
the mill viii cost in the neighborhood OF
100000 when completed"
In addition 20 the above mill The To- !
napah Mining company is erecting 100 |
stamp mill al Miller's Siding. II miles |
west of Tonopah At present sixty stamps |
are in operation and the returns are re- |
ported to be satisfactory. Another unit |
and in the course Of few weeks the |
mill VIII be operating seventy stamps, |
with capacity OF 400 tons daily, In ad- !
dition to the above mills the Tonopah |
plant III Tonopah, known as the Midway /
mill.