Custer weekly chronicle. [volume] (Custer City, S.D.) 1890-1931, 1907-09-28
MILLING AND CYANIDING
IN THE BLACK 6

OF interest, not only mere, DuL 10 LDt
mining world generally-frst, because
they are thorough in character second
because they are of a diversified nature
Their result is being awaited with keen
interest here and will likely have an
important bearing on the future of min,
ing operations in the Hills.
Something over year ago most of the
mills in the northern Hills adopted the
wet crushing process in cyandation.
Since the early days the dry crushing
method had been practically the only
one in use in this section. The reason
for this was that for many years there
was no known treatment Of shines
where any extraction worth while could
be obtained. The companies we're con-
tent to plod along with the dry crush
ing, the average fheness OF the ore
crushed being about an eighth-inch
mesh. Another reason was that with
straight cyaniding ore containing no free
| gold 1t was necessary to get the pulp
wet in order to go over the plates. This
| dry crushing was a combination of
crushers and rolls. 1t greatest disad-
vantage was the fact that the mill oper-
alive could withstand the effects of the
dust but limited number of years, and
it is a well known fact that the saving
Of lives was powerful incentive in
bringing into use the wet crushing meth
cd. For years every company using
the dry crushing style in its mill had an
annual harvest of death among the mill
men that was not overcome until the ad-
vent of the wet crushing process-an.
| other step to the inventive skill of mill.
men. With the dry crushing method,
the average extraction was from 65 per
cent to rs per cent. There was another
feature that appealed to the operating
companies: With the wet crushing the
wear and tear on machinery was not
great-in fact, much less than with the
dry crushing.
Today there are three methods of
treating shines in the Hills plants, the
recent invention of c. w. Merrill of the
HOmestake, which is now being used
by the company the Moore process, in
use by the Mogul Mining company and
the American filter press process in
stalled by the Reliance Gold Mining
company. The Moore gives from 80 per
cent TO 50 per cent extraction in the
shines, the Merrill claims 95 per cent
and the American filter press is yet to
be demonstrated thoroughly. These i'm
proved systems of treating shines have
played part in the adoption of the wet
crushing process in the Hills. One rea
son is the better classifers, notably the
Dorr classifer used by the Mogul while
another is the improved Homestake
cone system, both of which have made
possible higher extraction and caused
the adoption of the wet crushing pro-
cess.
Fine crushing in the dry process is
productive of injury to the machinery
but the Coarser crushing is much less
| costly. Today the average mill in the
Black Hills is crushing with the wet pro-
cess to a forty mesh. which will un-
doubtedly be made finer with time.
Most of the ores in the Black Hills are
of the oxidzed silicious, known as brown
ores. There is some blue, which if
crushed to an eighty or one hundred
mesh, or even finer, will yield as high
an extraction as the brown ore, provid-
ing that the acidity is eliminated from
the refractory ore, and it is then prop
erly cared for.
There is in the Black Hills almost
every style of machinery known in the
milling process which lends a wide in.
terest to the present experiments being
made in a number of the prominent
mills. For instance the Mogul uses the
Chilian mill. the Reliance the Trent and
Huntington; the Golden Reward the
Huntington and Chilian; the Home.
stake the filter press of the Merrill in
vention the Maitland the decantation
while the Wasp No. has succeeded in
treating at profit So ore with the ordi.
nary crushing and some special feature
of Manager Gray. Each Of these sys.
TENS are undergoing test in the res
pective plants. In the Southern Hills,
the Saginaw Gold Mining company has
recently installed the Goode National
pulverizer, whose feature is revolving
disk crusher. This granulates the ore
which is free milling, and the company
expects to show high results in extrac.
ton. The Downie- Wright mill is in use
one being now installed in the Ivanhoe
with a fifty ton capacity. This mill is
somewhat similar in plan to the Trent
and Chilian mill.
These experiments should demon
strate with accurate data the primary
costs for each mesh and the fneness re.
quired for each ore, the amount and
cost of power necessary for each meth
cd and other similar important informa-
ton.
Up to the present time, even with the
costs of the first installation of stamps,
which is heavy, that method appears to
have proven the most successful The
Homestake Mining company regarded as
the largest gold mining company in the
world, uses 1000 stamps and has found
that system the most practical and eco
nomical. One important feature in the
use of stamps is the fact that when max.
ing repairs it is not necessary to shut
down the whole mill. One battery OF