The San Francisco call., 1903-12-11


One Of EuroDe's experimental scien-
lists claims to have discovered that
metals can be killed by poison, put to
sleep by ehloroform, made drunk by
whisky and crazy by cocaine. He de-
clares with much confidence that
metals possess many human attributes
and broadly intimates that he is the
first man TO prove it, But every foun-
dryman and blast furnace man for
years has known that one metal at
least has much akin to human in il.
This metal. called the most useful of
metals, is always seeking its affinity.
IT is a sad fiirt; a veritable cOquette.
In its course from the crude ore to the
finished product it runs the gamut Of
love and hate, and its intigues and
escapades keep the blast furnace and
cupola in a turmoil. This metal is iron.
Chemically pure iron has no CONNER
cial value. Its impurities. called metal
loids are what give iron its character
and strength. The iron ores as they
come from the mine are combination
Of iron, oxygen. silica, phosphorus, sui
phur. carbon and other elements, and
the blast furnace is employed to sep
arate the metal from the ore impurities.
Pure iron ore is a chemical combina-
tion Of metallic iron and oxygen. the
most common consisting of about 20
per cent iron and 80 per cent oxygen.
But the earthly impurities and combina-
tions Of other elements entcr so init
mately into the structure OF the iron
ore that the blast furnace man must
raalrnr, all .F -, Ii
TO separate the metal from the dross.
in the process of the reduction of the
ore the oxide Of iron-the becomes
carbide Of iron-pig iron
The blast furnace is a huge brick
stack not unlike a gigantic bottle
standing on its cork end. The ore.
coke and limestone are fed into the
stack on top, and the melted, refined
iron escapes from the tap hole in the
bottom and runs into open sand molds.
where it cO0ls into the pig iron of
commerce. This pig iron contains from
90 70 - per cent of pure iron and to 6
per cent Of impurities. Before it can be
used in the arts this pig iron must be
remelted in a pudding furnace - or
some other kind of furnace or the
cupOla of a foundry
Immense air comDressors are used in
the reduction Of the ore in the blast
furnaces, for each ton of iron made
requires from three to six tons of air,
which is forced into the blast furnace
under q. pressure Of five TO ten pounds
to the square inch.
This blast Of air is heated to a tenn
nora fn1ve I'M bfvl, 1500 IaUraoe,
Fahrenheit before it enters the furnace
The air pumped into the furnace ex-
ceeds in weight the combined weight
Of al the ore, coke and limestone
which is charged into the throat"
Of the blast furnace.
A blast furnace eighty feet high is
about twenty-three feet at its largest
diameter which is about twenty-five
feet from the bottom. From this point
the stack tapers both ways About
eight or ten feet from the bottom the
furnace becomes a cylinder. The top
Of the furnace is called the throat"
the lower part the "boshes" and the
cylindrical shaped bottom is the
hearth" About four feet from the
bottom are the tuyers," through
which the blast enters the furnace, and
the tapping hole" is almost at the
bottom.
In order to separate the foreign mat
ters present IN the ore from the iron
an intense heat must be used and the
fuel is coke, anthracite or charcoal.
Fluxes are required to facilitate this
separation, and limestone is the ma
terial most employed. The fuxes trans
form The earths and extraneous mat
ter into Stag, which is used afterward
for railway ballast and for making
cement and bricks.
The blast furnace is divided into
three zones; above the hearth comes
the zone of classification, next above
that is the zone Of fusion and above
that the zone Of reduction. These
zones have no well defined boundaries.
for they merge into eacn other almost
insensibly As the iron passes through
these divisions or zones il makes des-
perate love TO the oxygen. carbon. sill
con, sulphur and phosphorus, leaving
one 20 take up the other, flirting and
coquefting until at last, welded for
the time being to carbon, it emerges
quietly from the tapping hole a
steady, substantial citizen of the in
dustrial world.
The iron ore. coke and limestone are
not thrown into the blast furnace hap
hazard. on the contrary. the mixture
is made on q well considered plan, de-
termined by chemical analysis. The
proper proportion Of ore to coke and
limestone is established by the chem
icaI makeup of the fuel. fiux and ore.
1 When the mass is once in the furnace
and the oxygen-bearing blast is roar
ing through the tuyers and driving hot
gases and air up through the spongy
coke and ore the iron, warming up,
begins TO shake off the oxygen which
has been it's companion underground
! for years. AS the metallurgists put it.
| the ore parts with its oxygen TO the
carbonic oxide, forming carbonic acid.
The ore, shedding its oxygen, descends
( into the zone of reduction, and here the
iron begins making violent love to the
carbon, absorbing it greedily-that is,
/ il there is not much silicon present.