Idaho County free press. [volume] (Grangeville, Idaho Territory) 1886-current, 1890-05-30
A NEW IRoN-sILvER PROCESS.
Direct BIast-Furnaee Smelling.


To the non-scientific reader who NAV
have felt sufficiently interested in these
matters TO have followed my notes thus
far, 1t Is but fair to offer few lines in
orief explanation of the furnaces, and
their principles and modes of operation.
as applied TO such smelling of ores for
crude products.
First, and most ancient, is the blast.
furnace. or "shaft-furnace," as it is now
distinctively called, which consists of n
hollow shaft of from five TO len feet in
hight, from the charging door where
the fuel is introduced, to the bottom of
the interior.
This manner of furnace was formerly
constructed Of fire. brick, but recent i'm.
provmenis have developed it into the
American water. jacket smeltel;" i'm
which no brick is used. or in which a
brick lining is used only above and be-
low the hot region.
In these shaft-furnaces, or blast fur
haces, which are essentially similar to
the ordinary iron-foupdry "cupola," the
fuel and the ore are piled, alternately.
one on top of the other, in separate
charges; making continuous column.
which extends from the bottom of the
furnace to the charging door and which
Is all the time built up, during opera
ton, by fresh charges of fuel and ore at
the top, as the burden sinks from burn.
ing and. melting away at the bottom;
4 thus keeping the shaft always filled up.
The fuel is bred at the bottom, and
the combustion is kept up by blowing in
large volumes of air through a number
of apertures situated near the bottom of
the furnace.
The quantities of fuel and ore intro
duced are carefully proporiioned, the
one to the other, SO that the heat from
the combustion of the former will lust
melt the latter; and the final products
of this fusion, which consist of matte
and Stag, are permitted to flow out
through suitable apertures at the bot
tom of the furnace.
The Stag is produced from the fusion
OF the gangue.rock of the ore with such
huxes as may be necessary to dissolve
il; while the matte contains tho valua-
BILE metals of the ore, in combination
with sulphur and part of the iron
which may have been present. Very
nearly all the iron present as oxide, in
ores and fluxes. goes into combination
IN the Stag, while very nearly all the
iron which may have been present as
sulphide goes to make up the matte.
This matte may be further concentra-
ted. .subst quently, by "ioasting" or
burning out part of the iron and sui
phur at low heat, without fusion, and
then resmelting this roasted product
with enough silicious (quartzy) material
to make Stag with the burnt or oxi-
died iron.
Such is, briefly, what is meant by
"blast-fnrnace-practce;" and in marked
distinction from this, is the secoad, or
"reverberatory system" of smelling
known through the wide world as the
Swansea, or Welsh, method.
This had its birth according to Vivian,
some 300 years ago. in Keswick, Cum
berland, England, under the paternal
care of one JOACHIM Gaus. And from
there the process was introduced into
South Wales, where it became in time
the leading copper process the world.
The reverberatory furnace il an i'm
mense oven, which is heated by the
burning gases in their passage through
it; the fuel being usually fired on a
CRATE, in fire hox which is separated
only by low bridge wall, over which |
the flame passes, from one end of the |
laboratory or smeltinp-chsmbel: the
fiue which conducts the waste gases to
the chimney, being placed at the other
end of the furnace
The charge to be melted is placed and
spread out on the floor of this oven or
melting and receives the heat
directly from the f1amt; and also from
the highly heated roof and walls of the
furnace, by reverberation or reflection.
The whole furnace is constructed of fire.
brick. and stayed with iron.
The melting is effected by heating of
the charge, from the top, in a manner
which permits and causes great loss of
heat in many ways: SO that, although
the fuel may be most perfectly burned,
so as to produce about double the GUAM
tity of heat obtainable from an eoniva-
lent quantity of coke, as imperfectly
burned in the blast furnace, vet the best
reverberatory practice of the present.
requires about three times as much fuel
as the blast-furnace, for the same work.
THIS fact is. however, frequently offset
by the fact that the blast furnace fuel ia
in many cases of more than three times
as expensive quality; wood and cheap
coal being suitable for the reverberatory
while the bast.furnace requires coke.
Returning to the matter of matte
for silver, and keeping in mind
the general principles upon which the {
process must be conducted, as set forth I
in my former papers, ct us now attempt {
to follow an ideal charge of ore through
the blast-furnace. Let it be placed on I
the top of sufficient fuel to melt it, and