Sierra County advocate. [volume] (Kingston, N.M.) 1884-1960, 1894-03-23
MILLING GOLD BEARING
ORES.

OhEO.
Denver Mining Industry.
All the discussions regarding
the comparative merits of the
Colorado and California stamp
mills, in which mill men and
miners occasionally Indulge, seem
to us to 30 carried on with so little
data that they are of no value
as proving their comparative mer-
its. They have decided educa-
tional value, however, because they
induce study and thought about
milling, methods; and they are
things that will be benefited by
all the thought that may be given
them.
There are not very many facts
that can be set down as positively
established by proof, regarding
their merits for general use. And
| in fact it is doubtful whether many
| facts could be established for that
purpose, solely because there is
great difference in milling ores OBJ
tanned from different mines and
different regions, each one requir-
ing different treatment from some
other ore to obtain the most profit
and this difference may pass
through all the gradations from
slight to radical-that generaliza-
tions on that line may be impossi-
BILE.
Some few facts, however, of con-
siderable value, seem to be estab-
lished. Among them ale these:
The California mill, as generally
understood, has a rapid drop and
slow discharge, and treats from
two to three and half tons of ore
per stamp each "a hours. The
Colorado mill has high discharge
and slow drop, and treats from one
to one and half tons per stamp
each "a hours. This is the charac-
teristlc difference in the mills.
1t is positively established that
for most Colorado ores the slow
drop Ind high discharge gives the
highest saving and most profit. 1t
is said that the opposite is proven
for most California ores. We have
yet to see the proof of the claim.
Another thing that is proven, or
claimed to be proven, ls that the
slow Colorado method will save
more of the gold in the ore than
the rapid California method. This
saving is placed at from 10 to 90
per cent, each man who goes onto
this dangerous mathematical
ground apparently forming his
opinions from his own field OF
observation, which with all must
necessarily be limited within mar
row bounds.
The balance Of authority seems
to be in favor of the claim that the
slow method saves the highest per-
centage of value. The question
often revolves itself, then, into
this: Will, in any particular case
more profit be made by the slow
than by the fast method?
In one case the California mill
may treat three tons every "a hours
saving 50 80 per ton, at cost of
SO cents per ton. BY adopting the
Colorado mill the saving may he
increased ID per cent. or 20 cents
per ton. But it may be at an ex'
pense of one and half tons capac
ity and the increased cost may be
so cents per ton, the result Of
which would be net loss OF 20
cents per ton. "1
In most cases the problem seems
to resolve itself INTO this: 1t the
ore is high grade. the increased
savings in the Colorado mill more
than cnmpensates for the loss OF
capacity and the increased cost per
ton. If il be low grade the lncreas-
ed saving may not be enough to
pay the increased cost.
Then, as arriving at the final
question of profits. the saving OF
concentrates from tailings, and
their vasae, as governed by their
contents, and the cost of getting
them to market and their value
when delivered at smelter or chlor
riassk;aa. .Eaxk.s--is-a.iaesor which
may be decisive.
Between the extremes OF slow
drop and high discharge, and rap
i'd drop and slow discharge, there
may be any number Of compromis
es to get the best results on the
ledger.
The fact is that eacIi case should
ie decided nm rts own merits. and
these can be determined only hy
trial Simple teets, and careful
study of the ore, by One who thor
oughly understands his business,
are very valuable, and may be suf-l