Mohave County miner., 1892-04-16
I'VE xAc AsrSus-fosaEsr PROCESS.
Tho Experiments in California.
mining and Scientific Press
MIDDLE CREEK. Shasta Co.,


April 4, 1892.
To THE EDITOR being generally
known that the Calumet Co. was the fret
to introduce the MacArthur-Forrest pro.
cess into California on any practical work.
ing scale, my time has been considerably
taxed In answering letters from very many
mining men. not only in California. but
elsewhere. all inquiring as to the prscti-
bility Of tho process, ETC., et'. Seeing so
many are interested, | have concluded to
write description OF it, giving data 80
many desire, and let you publish 1t.
To preface, the process WAS FIRST pro-
meted by the Cassei Gold Extracting Co.
Of Glasgow. Scotland; from there il was
introduced into Australia. South Africa.
New Zealand, and the United States.
The patents for this country are held by
the siold and Silver Extracting. Mining
4 Milling Co. Of Denver, Colorado, Of
whci, ex Senator Tabor IL president, and
Col. T. l.. Wiswsll. secretary. This com.
pany WAS formed some two years ago,
but little progress WAS made, however,
until within the past year, and since the
Denver company completed their l5-ton
mill and commenced working ores. which
gave such unexpected and satisfactory
returns, in the way Of high per cent, that
every investigator was filed with wonder.
and saw the revolution likely to follow.
On my attention being called to it. now
one year ago. at once started for Denver,
and WAS allowed all the desired privileges
for close investigation. The more in
vestigated, the more merit the process
presented, and soon became convinced
that II was worthy Of more than pass
ing consideration IN fact, In my own
mind, concluded to "sail In" and find
out all about il, on practical working Of
ou- own ores RetureIng to California. I
commenced = series OF experiments,
agreeable to instructions received in Den.
yer, from their leading chemist, and soon
made better results on our ore than made
in Denver. II now took no time to de.
eide as to the propriety Of introducing
the process on large scale in the Calumet
mill, under nv manafement, and where
it is now doing satisfactory work and be-
ing extended, and will be up to 100 tons
a day.
1t may be information TO many to state
that in South Africa 13 mills are now
operating the process with great success,
and that mills are already in operation in
Colorado, Utah, Montana, Dakota and
California. At the .ieedles, in San Ber-
nsrdino county, 100-ton mill is in course
Of erection. Being among the first in
this country to accept its merits, ] fancy,
by this time, know something about it,
and hence presume to speak.
The MacArthur-Forrest process Ia the
use OF . weak solution Of cyanide Of
potassium. Tho strength Of cyanide
should be. As testing your ore will show,
the proper per cent for extracting the
highest per cent Of the precious metals,
say from one-half OF per cent to ~,
then treating your ore for q given length
OF time with this solution; time for treat
ment is according TO the character Of
your ore and metals, how much base and
what kind. To get at this correctly. q
few tests are necessary; but it is easily
worked out. And here, it Is proper 10
state. that time il more the factor Of y,er
cent than q high per cent Of cyanide.
We have made many tests on this point,
and all clearly establish this fact. have
failed in per cent Of extraction on some
ore, and then, by q few experiments,
gained high per cents from same It il q
process Of study. but once you get time
and per cent determined, then there IL no
failure in your extraction fum that
especial ore, no matter to what extent
you may 20. SO tue has this been with
our working. on small and large scale,
that taking any ore, from anv mine. I
would not hesitate to build = 5O-ton mill
on simple test OF fifty pounds, II the
per cent Of extraction WAS satisfactory.
There are two modes Of having action
from the cyanide on the ore; one 10 by
agitation, and the other Is by time and
percolation. Revolving barrels, or set
tiers. ~ used at times in silver mills.
make good agisators. The percolating
plan Is the use Of large tanks. whereby
the ore rests In the solution and in time
is percolsted off into reservoirs. Agita-
tors take attention and power; rercoIs-
ton, less attention and no power; besides,