The Goldfield news. [volume] (Goldfield, Nev.) 1904-1911, 1907-08-31
NEW MILLING PROCESS
A COMPLETE SUCCESS

Tonopah. Aug so.-The mill of the
Montana Tonopah IL dropping twenty
stamps. and would be dropping the fun
forty II II were possible to get the re-
auired power. II has been demonstrated
that the plant r. a perfect success In
every particular. and this fact II Of the
utmost importance to the camp. and to
the Montana Tonopah especially. As to
the practical workings Of m mill. the
following details were obtained from Mr..
r. l. BosquL. the designer. and under
whose direct supervision the structure
has been erected:
"Th ore II delivered from the mine
Z No. 5 Gates crusher. and IL further
reduced in two No. , Gates crushers.
From the crusher house the ore. thus re-
duced. II elevated by a belt conveyo to
the mill bins. The mill il OF forty
stamps. with . capacity Of 200 toni q
day. Only twenty stamps are operating
at present for want Of power.
The ore IL concentrated on Wiley
tables. then passed through two s-foot
by 3z-foot Gates tube milis- The prod
uct from the tubs mills In hen recon-
centrated before passing to the cyanide
plant. The ore n thereby reduced to
about $50 mesh, and the concentrates
practically removed. These concentrates
are shipped TO the smeiter.
Tn the cyanide plant the slimed ore IL
treated with . cyanide solution in six
Hendrix agitators for - hours. 1t IL
then Uttered in q Buffers vacuum filter.
and the solutions leaving the filter are
precipitated on zinc dust in the Merrill
precipitation presses. All the gold and
silver extracted in the cyanide plant IL
by this means precipitated on n zinc
dust and held in these presses. The pro-
cess of cleaning up is thereby greatly
simplined. ~inasnsuch as it simply means
opening up the presses once a month; an
operation which will require the services
of two men for about two hours.
Tho tube milling of ore has been
practiced for several years past In Aus
tralia and elsewhere. but so far as IL
known, his IL the first instance OF It's
application to an ore carrying so large
a proportion OF silver. The average
grade of ore milled Is about twenty
ounces Of silver and about 81 in gold
In this plant, teaching in tanks has
been lone away with altogether. and all
the indications from results of tests. ana
from the operations in the mill are tnat
an extraction between IS and 30 per
cent. in "a hours. can be maintained
from this ore, which would require by
teaching. from ten to fifteen days. While
the plant has been running only a Few
DAYS. 1t has been demonstrated TO the
satisfaction Of the designer that the mill
is practically perfect"
A good many tests had been made on
the ore at different times. and the mat
ter was finally put into the hands OF F.
L. Bosqui. who enjoys the reputation OF
being one Of the greatest cyanide au-
thorities in the United tSates. A series
of tests were made on a carload OF the
ore at San Francisco and Denver. These
results were oficially accepted by the
mpa and Mr.. Bosqui was asked 10
design the mill on the basis OF those
tests. The latter was busy on the work
Of testing for six months. and the actual
work on the mill occupied abou a year.
The ore Of the Montana Tonopah IL
not a simple ore to treat. as 1t carries
antimony arsenic and zinc. and 1t was
necessary to concentrate very thor
ou1hly in order to make the cyanide
nrocess effective. The difference be-
tvaer the ores Of the Montana Tonopah
and the Tonopah is that the former are
sluphides, while those of the latter are
oxidized. The Midway and the Extern
sion ores do not differ materially from
those OF the Montana Tonopah.
A number of mill authorities have
visited the new mill. and all agree IN
saving that it Is perfect. A large part
Of the credit for the fine construction OF
the mill is due to Mr.. John Horgan,
chief OF construction for the Montana
Tonopah; and the satisfactory work IN
wiring the buildings for the electric
mower il due to Mr.. Leon Cummins, OF
the Nevada Power company. All the
machinery of the mill. with the excep-
ton of the Hendrix agitators and the
precipitation presses, was supplied by
the A~llis-Chalmers company.
The Midway mine IL in most excellent
shape, and has a hill full of ore. On the
435-foot level. and the 5S5 level. ana
the intermediary of those levels. they
have drifted for hundreds of feet. and
are still drifting. The ore Is OF a high
grade all through, and the ledge ex-
tends from four feet to ten feet. The
walls and ceiling glisten like a house OF
crystal. II this ore were to be shipped
as 1t Is broken down. the majority OF 1t
would be of very high value; but 1t IL
sorted for shipping. and there is only
enough being sent to the mill to keep
things going. and the treasury In sub
stantial condition.
The principal work being done at the
present. il the prospecting of the lower
levels. This work il going on mainly
on the eight hundred-foot level. and the
success Of 1t means much. not only to
the Midway, but to all Tonopah. They