The mirror. (Stillwater, Minn.) 1894-1925, 1919-02-13


freedom from impurities and be-
cause it is generally considered
that iron produced with charcoal
is better for some purposes than
if made by using other fuels.
These materials that are charged
into the furnace with the ore to
assist in removing the elements
that it may contain are called
'fuxes." They collect the impuri-'
ties and form slay which floats on
the molten iron and is tapped off
before the metal is allowed to run
out. These fuxes also assist in
protecting the lining for the fur
mace by thus absorbing the impuri-
ties which would otherwise attack
the lining and destroy it. Lime
stone is almost universally en-
ployed as a fux. The value of
limestone depends upon its freedom
from impurities, such as silicon
and sulphur, as these two latter
elements must be kept out of the
product.
The molten metal is then poured
out by blowing air into the fur
mace to increase and hasten COM
bustion and is called the blast,
where the molten metal runs into
large ladels and is transported into
the open hearth. This iron is
known as the Bessemer iron used
for making Bessemer steel.
The most common steel-making
process is the Bessemer process,
which may be sub-divided into the
acid Bessemer and the basic Bes-
semer. The operations used are
the same for both the acid and the
basic process to- certain extent.
The chemical reactions differ SUBJ
stantially, however. Briefly de-
scribed, the basic Bessemer pro-
cess consists of charging molten
pig iron into a vessel called con-
verter, forcing a blast of air
through it until the silicon, man.
ganese and carbon are burned out,
and restoring q definite portion of
manganese and carbon by adding
a recarbonizing material. This is
the process in skeleton. 1t divides
itself for the purpose of detailed
consideration into the following
divisions: Apparatus and mechani-
cal manipulations, and chemical
reactions. but the central feature
of the plant for making Bessemer
steel is the converter. This is
pear-shaped vessel of steel. lined
with a refractory material. The
vessel is mounted on horizontal
axes, consisting of two hollow
trunnions, through one of which
the air blast enters the bottom of
the converter. The blast is kept
by blowing, which keeps the pres
sure from twenty-five to thirty
pounds per square inch. The blow
ing continues from seven to twelve
minutes. Then the converter is
turned upon its side and the re-
carbonizing material, spiegeleisen
or ferro manganese in molten form
is added. This charge is then ready
for casting.
This operation consists first of
drawing the contents of the con-
verter into a ladle which is swung
into position under the converter
by a crane. The ladle IS then
turned over on it's side and the
molten metal is poured into molds
called 'singots," which are mounted
on small platform cars and filled
one at time. After a sufficient
cooling these ingots become solid
apd their molds are slipped off by
cranes called ''ingot strippers" and
placed into the soaking pits. These
pits are flaming mass of fire and
are generally made of regenerative
type and are divided into several
compartments, each capable of re.
ceiving several ingots, which are
inserted on end. These ingots are