The Washington herald., 1909-02-14

tariff Charles n SchwaD was the wit
ness and he gave the committee de-
tailed. account Of what had been accom- +
pHshed by the electrical furnace in the
business Of metals. His testimony abbre-
Waited and accompanied by illustrations,
appears in the current issue OF me Iron
Age
Mr. Schwab declared that in his opin-
ion the development Of the electrical
furnace would De such in ten years
time as 10 supersede the open hearth
process. Upon this as a text, the Iron
Age saws:
The development Of the uss Of the cleo
tricaI furnace in the metaIlUrgy Of iron
and steel has been very backward in this
country as compared with what has
been done IN Europe The reasons for
this are various. bur among the chief
Of these are the lack Of an incentive 10
md uses for idle hydrOelectric plants
and ve-y favorable conditions surround
ing the iron and steel industry In the
United States However. these favorable
conditions are not what they were some
years ago. and AT the same time the de-
mand for quality IN steel has become
more rigorous. SO that now the great steel
makers are following with Keen interest
the development Of numerous types Of
electric furnaces in Europe
Open Hearth Furnace.
The rapid replacement OF the bessemer
furnace by the open hearth is due in
part 10 the growing scarcity Of the So
called bessemeT ores and the increasing
demand for a quality Of steel that can
be made only in the open hearth fur
mace. The treatment Of metal in the
bessemer converter consists chiefly Of
burning out certain impurities. but il
cannot be used ike the open hearth fur
mace for the chemical treatment Of iron,
which is frequently a process involving
a considerable period. Of time
The heating Of the metal in the open
hearth furnace Is accomplished by Caus-
ing a stream Of incsdeseent gas TO pass
over the surface Of the bath. the heat
passing by cOnduCtiOn and radiation from
the flowing gas 10 the metal The rate
az which the heat flows into the metal
is proportional 10 the difference in tenn
DGLALlE@ BGL-C C-LL Llle Ed1 CAAtA LllE -AAE-e4A
consequently the higher the tempera-
ture Of the latter. the slower is the
transfer OF heat Moreover. the aJmos-
phere above the surface OF the bath is a
powerful oxidixer, and this naturally
affects the chemical reactions which
take place
There are three ways in which the cleo
tric current may be used in heating steel
fn-a .ar-
formed between electrodes and the bath
Of metal, u an arc OF several arcs may
be formed between electrodes situated
above the metal and the heat radiated 70
the bath: 81 an electric current OF suf-
dcient volume may be passed through
the metal 10 heat il 10 the desired de-
gree.
The HerOuit Furnace.
TIE diagram in Figure Illustrates the
principle Of what IS usually called the
Heroult furnace. The current is sup
Piled from d 10 the electrodes Fl and e,
which pass through holes in the roof Of
the furnace and are suspended above the
Stag S. which covers the molten metal
NJ If the current is imagined as fiow-
ing from D 10 Fl il then passes from e
10 y. forming an arc, and then from N
10 E2. forming another arc The in
tense heat Of the electric arcs passes "a
the metal Immediately below them and
the molten metal IS strongly agitateG sc
that the whole mass is heated
There are various ways in which this
furnace may be used for the manufac-
ture Of steel The furnace may be
charged with a mixture Of pig iron and
scrap. and the electrodes lowered unit
contact IS formed between them and the
metal Then electric arcs are formed
and with terrific noise the metal melts
finally forming a bath on which lime Is
thrown 10 form a Stag. Then the work
ing Of the furnace becomes perfectly
quiet, and It would hardly be realized
that anything was happening in IL were
IT not for the dazzling light from III:
electric arcs. by means Of which TEN
peratures can be obtained which neve'
can be reached in a fuel furnace
Another method Of working is to tsk'
molten metal from al open hearth fur
mace or a bessemer converter and pour
into the electric furnace. where II is fin
ished- This is the method which vii
probably be most extensively develOpe,
IN existing steel plants. for while Il
true that il places where fuel is YER
dear ard where the electric current cal
be cheaply obtained from water powe
70 may be cheaper 20 use electricity fl
the whole process Of manufacture. ye
in most places It Is far cheaper 10 use
combination Of fuel and electric heatini
the latter being used where the highes
temperatures are required.
The Girod Furnace.
The Girod furnace differs from tha
used by Heroult IN that the current doe
not 1ow from one electrode 10 the stee
bath and thence 20 the other elecrode
but passes from the electrodes to III
bath and thence 10 the bottom OF III
furnace. which forms the other terminal
The diagram in Figure illustrates N
way in which the furnace is worked
As in the Heroult furnace the electrode
Fl and e pass through the roof and ar
suspended above the stag S covering tn
bath Of molten metal N, but both th
electrodes are connected 70 the sam
side OF the circuit coming from tn
source OF electric current D. The Othe
side Of the circuit Is connected to tn
terminals y. situated in the bottom O
the furnace These terminals are mad
OF steel ana are wafer eOOleG 70 preNeT
them from melting. Thus II the curren
is imagined as flowing 10 the eIectrode
from ., Il forms arcs between these an
the bath. just as in the Heroult fuTnact
and then passes out through the bat
and the steel terminals W
The method Of using the Girod fur
mace is similar 10 that employed wit
the HerOult furnace.
The StaSsano Furnace.
The principle on which the Stassan
furnace works is different from thos
hitherto considered. for the metal doe
not form part OF the electric circuit Fig
ure is a diagram Of the furnace, frol
which II viii be seen that the electrods
enter the sides Of the furnace horizon
tally, so that an arc s formed betwes