The Anaconda standard., 1899-08-08
PYRITIC SMELLING.

An article IN the Engineer ana Miner
describes the process af follows:
"Pyritic smelling is a method of smelt-
ing ore by utilizing the heat generated
by the combination of the sulphur con-
tents of such ore.
''All metals, whether precious or base,
for the most part are found in nature
combined with sulphur in various pro-
portions in which cases they are known
as sulphides, sulphurates or pyrites of
the respective metals.
For the purpose of pyritic smelling
the suphides or sulphurates of gold and
silver and the rarer metals may be ig-
nored, as their amount is relatively too
small to be of any consequence; but the
pyrites of the base metals, especially the
pyrites of iron and copper, are found in
large amounts, and the proportion of
sulphur contained in them varies from
% to 60 per cent the heat-generating
properties are of great Importance
Heat is produced from sulphur by
oxidation, and the readiest and simplest
way of effecting oxidation is by causing
the oxygen of the atmosphere to unite
with the sulphur, which it will do when
the sulphur is in the fused or fluid con-
dition, which it attains when at a high
heat. The result of this combination of
oxygen and sulphur is heat; and sec
ondly, sulphurous acid gas which passes
off into the atmosphere as a white smoke
or fume of yellowsh tinge.
Heated sulphur readily untes with the
oxygen of the air under almost any con-
ditions where the two elements are in
contact. the purer the sulphur the more
rapid the combination or combustion.
When, however the sulphur is in combi-
ton with iron, copper or other metal the
dissertation of the sulphur from the met
al and its combination with the oxygen OF
the air is a slower process. In order to
hasten the process, the ore is placed in
a furnace and air is forced into the fur
mace by means, preferably, of positive
or pressure blower The result is very
high degree of heat and the melting and
fusing of the contents of the furnace.
When in the fused or fluid condition the
metals contained in the furnace charge
readily break from their previous combi-
nation with the sulphur or other elements
and group themselves according to their
specific gravity, i. e., weight.
"In order to produce the best possible
results from the smelling operation the
ores and materials treated in the furnace
must be fed in certain proportions In
fact SO important is this matter of pro-
portions that any error is almost certain
to entail a failure which will be of a very
costly nature.
1.-The most favorable change for a py-
ritic furnace is one consisting mainly OF
iron pyrltpS with a ilIlllleu dIIoulil VI
conner ore of any kind, and preferably,
of course. copper pyrites. With charge
of this kind copper Is used as the base OF
tn, operation, as when the charge is in
a state of fusion the copper falls to the
hnttom of the furnace or crucible and
into 1t are preciptated also the precious
metals-gold, silver, etc, contained IN all
the ores.
"a furnace can be operated successfully
xNrhn a
the charge amounts only to as little as
or per cent.
"In order to get rid of the iron con-
tanned in the furnace a proportion of sill
lea or quartz is mixed with the furnace
charge and this combines with the iron
to form Stag, which is readily drawn off
from the furnace when in a fluid condi-
ton and discarded.
"A certain amount of lime or lime rock
also forms part of the furnace charge
and is useful as flux. that is facilitating
the fusion melting of the minerals and
the denominations that have to take
place.
1.-THE product of a furnace charge, as
above outlined, is a copper matte, an
combination OF copper, iron, silica and sui
phur, and should include also the precious
metals-gold. silver, etc. The proportion
of copper in this matte may be anywhere
from % to 60 per cent. Consequently the
smelling operation is really concentra-
ton rather than a refining of the metals
sought to be extracted. The copper matte
produced can be advanced a further stage
toward refining by repeating the smelling
operation in a similar furnace, but with
different proportions of fuel and fiuxes.
I'm making up a charge or mixture for
the pyrtic or other smelling furnace,
some proportion of fuel must be included,
coke or charcoal being the most suitable
kind The larger the percentage of sui
phur contained in the ores the smaller the
percentage of fuel required. In a pyritic
furnace with a charge having maximum
Of sulphur the smelling can be effected
with as low as 21a per cent of coke to
the charge. Other fuel, however. is need
ed to insure the best results. The blast
or air that is forced into the furnace must
be heated before entering the furnace by
means of blast stove. For heating this
stove any kind of fuel can be utilized.
Pyritic Smelling Without Fuel.
1.-THE practical metallurgist has given
up the notion of smelling without fuel.
Whilst the theoretical heat produclple