The Baltimore County union. [volume] (Towsontown, Md.) 1865-1909, 1903-11-28

OC DlOWu lulOuSu pig AlOH1 TIC GULL
bustion of the impurities in the iron
will furnish sufficient heat to keep
the metal in liquid state. The lin
ing of the converter in the Basic pro-
cess is of hard burned dolomite, a
limestone containing about 80 per
cent. to 40 per cent. magnesia. In
this process the silicon in the iron is
kept as low as possible, as the oxide
acts on the lime lining. Phosphorus
is used to take the place of silicon and
to supply the heat needed. 1t is
therefore evident that low-silicon
and high-phosphorus iron is needed
in the Basic Bessemer process. The
final operation of adding manganese
is the same as in the acid process.
The phosphorus is oxidized and pass
ed into the Stag. The Basic process
is not used at all in this country.
THE OPEN-HEARTH PROCESS.
The open-hearth process gets its
name from the fact that a furnace is
used having the hearth exposed to
the flame so that any material placed
upon the hearth is exposed openly to
the action of the burning gases. This
process is divided into two different
processes, the acid and the Basic.
THE ACID OPEN-HEARTH PROCESS.
The term "acid open-hearth fur
mace" means a regenerative gas fur
mace used for melting steel and hav-
ing bottom lined with silicious ma
terial, generally sand. The bottom
in itself plays a very little part, but
the character of the bottom deter
mines the character of the Stag to be
carried, and this determines the chem
istry of the process. In this process
a mixture of pig iron and scrap is
thrown into the furnace and melted.
Nothing is added to form Stag as
the combustion of the silicon and
manganese, together with some iron
that is oxidized, and some sand
from the bottom affords a sufficient
supply. When the mass is melted it
is fed with iron ore, and the oxygen
of the ore oxidizes the excess of car
bon until the proper composition is
attained. The metal is then tapped,
the proper addition of manganese be-
ing made at the time of tapping.
THR BASIC oPEN-HEARTH PROCESS.
In this process the bottom of the
furnace is lined with a basic mater
ial, usually magnesite or burned dol
omite, the same as is used in the
Basic Bessemer process. When the
bottom is basic the Stag must be basic,
and in order to get this small guam
tity of lime or limestone is added in
addition to the pig iron and scrap.
This mixture is all melted down by
the action of the fame, the silicon
and carbon of the pig iron are oxidiz-
ed, as in the acid process, and the
manganese of the scrap and SOME of
the iron are both oxidized, just as on
the sand bottom of the acid furnace,
but the silica and oxides of the iron
do not make Stag by themselves, for
they unite with the lime that has
been added. This gives basic Stag,
and when the Stag is basic the phos-
phorus in the pig iron and scrap will
be oxidized and enter the Stag as
phosphate Of lime or iron, just as it
does in the Basic Bessemer converter.
Thus the Basic-open earth furnace
will allow the publication of iron con-
tanning phosphorus, and for the same
reason but in very much less meas
ure, sulphur may be eliminated. After
the charge is fully melted, iron ore
is added as fast as necessary to oxi-
die the excess or carbon, and when
the metal has reached the desired
composition it is tapped into the ladle;
the addition Of maganese being made
in the same manner as in the acid
furnace.
THE CRUCIBLE PROCESS.
Most of the hard steel of today is
made in the open-hearth furnace, and
both the acid and basic processes fur
nish share. There are some pur-
poses, however, which call for steel
entirely free from the minute imper-
fections often found in open-hearth
metal. Such is the case in watch
springs, needles, razors, etc., and 1t
is found that the crucible process
gives the best metal for such work.
This is one of the oldest of steel max
ing methods and has charged but lit
tie from the first process used.
This process is carried out by put
ting into a crucible a proper mixture
of scrap, pig iron or charcoal and
heating it until everything is thor
oughly melted, the crucible being
kept tightly closed to prevent the ad-
mittance of air.
PITTSBURG, Pa.
Ill 81 IL