The Butte daily miner. [volume] (Butte, Mont.) 1885-18??, 1886-01-01

quality OF ore treated is SO different In the
two cnses referred to, and the employment
OF oxideOf manganese almost exclusively az
a fiux for silica in No. } is 80 interesting
and SO rare, as to demand separate
notice.
In Nos. 8, 4. and :: a certain proportion
of the ore is prepared mechanically for the
furnace by wet concentration, and as this
is the step that naturally follows mining,
it's description is il place here.
CONCENTRATION.
There are four separate concentration
works in butte, having an aggregate capa-
city OF about 800 tons OF raw ore daily,
and at least three more already about COM
pleted or in progress OF erection, which are
estimated to treat an additional 800 tons
per day. These Of course, are exclusive Of
the great works at Anaconda, which are ex.
pected to concentrate 500 tons daily, and
with sufficient furnace capacity to smelt
the concentrate produced.
In describing both smelters and concen.
traitors shall naturally make most use Of
such facts as are personally familiar to nae
as the netalurgist of what may perhaps
be considered the representative copper
works vi the district. l trust this may be
considered a sufficient excuse Tor any state.
ments that may not apply strictly to all
the establishments i'll the class referred to.
Our ores Of copper being mostly erubes-
cite and copper glance, have u sufficient
specific gravity ~ as compared with their
t quartz glngue (2.5), to permit OF a tolera-
bly, perfect separation, but the unfortunate
tendency OF these high grade co,.per miner.
ais I" form shines, combined with their very
high percentage in copper, necessitates Il
heavy loss i'll concentration, especially in
the fine taiIings, and one that can be only
partially remedied by expensive slime pits,
as the line copper dust once brought in con-
tact with water settles with extreme diff
Guilty, and long remains floating on the
surface Of even stagnant water. ..
| Another serious draw back in most Of the
mines is the occurrence Of pyrite, SO inti-
mately mixed with the ore as to defy hand
picking. Having nearly the same specific
gravity as the copper ore, and u less ten.
dency to form shines, it concentrates even
more perfectly than the valuable constitu-
ents,a positively prevents the production
Of a concentrate containing over from 20
to 30 per cent Of copper, except in the case
Of the Anaconda and one or two equally
fortunate Mines where the proportion Of
pyritc is SO small as to permit ola product
carrying from 45 to SO per cent. .aua.
| have made series OF careful expert
ments, with IL view to the discovery of
some means by which the iron and copper
minerals n! might be mechanically separated.
Finding that slight discrepancy in specific
gravity exists between erubescite and
pyrite hoped to obtain, at least on the
| first sieve OF the jig; Il product high in cop
per; but discovered, after repeated trials,
that there was just about enough difference
in the form OF the grains OF each mineral,
owing to the different cleavage planes (the
heavier mineral consisting mostly OF long,
fiat grains, while the latter breaks rather
into solid cubes). to effectually neutralize
any advantage that their differencein grav-
ity might offer. Failing in this trial the
next most promising idea seemed to lie in
the fact that the thorough exclamation of
iron pyrites, IA practiced with U.s. yields
principally u high magnetic oxide Of iron,
which quality hoped to take advantage
OF to separate it from the oxide OF copper.
But ON trial found that erubescite "a
compound OF iron, copper and sulphurl
also yields after calcination a highly mag.
netic powder. and that the result Of passing
magnet through ourcalcined concentrates
was to remove everything except whatsmall
percentage OF silica was present. Whether
this plan might prove more successful on q
mixture OF pyrites and copper glance
which latter mineral does not become mar
netic on roasting--l have not had the
opportunity VI determining
| While the concentration works now in
operation in Butte. AS well as those in pro.
cess Q, erection, are by no means model es-
Establishments. they still do very good aver
age work, and are perhaps quite as we'll
adapted to the peculiar conditions as more
elaborate works. The loss OF copper in the
tailings is considerable, and under eastern
conditions could not be tolerated. but it
must be considered that in Butte the ore is
the cheapest thing We have. while fuel,
labor and machinery are extremely expen.
sive, and that the copper contained in the
ore has cost SO little to mine that it does
not acquire any considerable value until a
certain amount vi labor has been expended
on it.
While do not deny that more
DerfeCt sizing n uraAoc svaforr ~ o..,.l,:n.