Weekly Arizona journal-miner. [volume] (Prescott, Ariz.) 1903-1908, 1904-06-08

ohN duai tclluB mcbuOhS anu assay gu.
The concentration was from eight to
fifteen tons into one ton of fifty to
sixty per cent copper matte, first
operation.
,. If the ore contains sufficient
sulphur to act as fuel, and hot blast
is used, the ore can be smelted for
less than half the regular cost of lead
smelling; in fact, for about what the
preliminary rolling and roasting alone
costs in lead smelling.
3. As twelve per cent lead is about
the minimum amount which can be
used in lead smelling and do good
work, eight tons into one is about
the best concentration; but in copper
smelling one or two per cent copper
in the ore can be the minimum
amount and do good work, and the
concentration is that much greater
accordingly.
4. There is a greater demand at the
present time for copper than for lead.
.. On account of the more rapid
smelling of the charges in the blast
furnace, greater heat and more silic-
ious Stag, as a rule, much more zinc
can be smelted without trouble when
mating than when lead smelling.
6. On account of being able tc
force more silica and zinc into the
Stag, it costs less for fiux.
Z. As there is no preliminary
roasting, if hot blast is used, nothing
but an ordinary coarse crusher is re-
quired for the largest Jumps.
8. A 200 ton plant where all the ore
would have to be roasted, unless roast.
ed in heaps, and then there is the
capital tied up for months in the ore
if hot blast is used so as to dispense
with fine crushing and roasting, car
be built for about one third the regu.
lar cost.
9. On account of being able tc
make greater variety of Stag with
out danger of serious losses, when cop
per mating, it is suitable for a great.
er variety of ore, excepting ore ricl
in lead, which should 90 to a regular
lead furnace.
10. On account of the advantages
just enumerated for pyritic smelling
it does not cost more than one third
to one half the ordinary cost of lead
smelling. OF course, if cold blast il
used, and ordinary mating resorted
to, the system has but little advantage
over ordinary lead smelling, except
ing that it requires less copper to save
values than it does lead, and a more
silicious Stag can be made when mat.
ting.
The question comes up. What ore
is suitable for pyritic smelling, or,
as | would call it, semi-pryitic smelt-
ing? The ore should contain suffi
cient SULPHUR to make the desired
matte necessary for clean work in go
first operation, usirr iael. IT,. a.
the sulphur is in excess q ,ie smount
required to form the matte, lie per
centage of fuel can and should be re-
duced IN the blast furnace, so that
the oxygen from the blast will unite
with the sulphur and not carbon.
Quite often, in my experience, after
using hot blast, when the matte got
over sixty five per cent copper. too
rich for clean work, the foreman
would add either more coke or more
sulphide ore, to reduce the grade of
the matte. | found mixtures-the
lime usually has to be added-Of three
per cent and over copper, twenty to
thirty per cent iron, eight to thirteen
per cent lime, up to ten per cent
zinc, ten per cent aiumina, thirty to
thirty six per cent silica, ten to thirty
per cent sulphur the safest limits
The original ore may carry a very high
per cent of zinc, alumina or sulphur,
but the percentages are reduced by
the time the ore is fluxed that is, the
excess of bases properly neutralized
with silica. OF course, too much zinc
is Objectionable, but it can be util-
lied to better advantage as a base in
copper smelling than in lead smelt-
ing; in fact, zinc blende seems to
give less trouble in a blast furnace
with hot blast than when roasting in
a reverbatory furnace, as it requires
also much mure heat to libeTate its
sulphur than when roasting ordinary
DTyites; and il must be with hot
blast that the oxygen, not having to
unite with fuel, has a better chance
to combine with the sulphur where
such an intense heat exists as in the
blast furnace. Of course, at times,
when it is Necessary, copper as low as
one per cent will anwser to save the
values. Some metallurgists claim
that no copper is necessary, and an
iron matte will save the values, and
mixtures containing much less iron
and more silica can be smelted to bet
ter advantage than those | have named :;
but II will make these notes too
long to 60 into the question of the
different combining powers of each
base with silica, and when each
should be added or reduced on ac-
count of the specific gravity of the
proper Stag to be made for matte set
Hing purposes.
The first heat required is Tor heat
ug he air blast up to the tempera-
ture wnen the oxygen will combine
With either the carbon of the coke or
tine sulphur contained in pyrites; then
the necessary heat for melting ores
and fuxes so that they will combine
10 form the proper siIicates for fluid
md clean Stag is produced by the
lXidizing of the fuel added to the
,harge by the free oxygen contained
IN the blast. If cold blast is used,
my free oxygen going in with it is
.equired TO oXidize the extra fuel re-
luired to heat the blast, thus leaving
lone for the sulphur. If more cold
blast is used so as to get still more
'ree oxygen. it drives the heat still
'urther away from the tuyere openings
n to the furnace and reduces fhe
.melting area of the furnace in that