The record-union., 1894-03-31
BESSBMER STEEL.
The Interesting Process of It's Manu-
facture.

facture.
The Bessemer converter belongs to the
order of clOsed-vessel furnaces, and its
fuel consists of the impurities contained
in the pig iron, which is poured into the
receptacle in q molten state This is a
pear-shaped vessel of thick plate iron
supported on standards by trunnions.
To one of these a piniOn is attached,
which enables the converter to be swung
through an arc of $50 degrees and thus
discharge the molten metal from its
mouth. The other trunnion is hollow
and ad mits the blast a pipe from this
trunnion passes to The WindbOX forming
the bottom of the converter, which is per-
forated by circular holes, from ten to
twenty in number, into each OF which is
inserted a conicaI fire-clay tuyere, per-
torated with ten or more holes about
three -eighths of an inch in diameter. The
converter is usually made in two parts
for convenience in refining, and is con-
structed to hold charges OF from five to
fifteen tons Of pig.
The acid lining is prepared by simply
crushing the silica rock under edge rolls.
and adding to it a sufficient quantity of
water to cause it to ball up when pressed
in the hand. This mixture is then
rammed between the iron she'll of the
converter and wooden form, placed at
such a distance from the shell that when
the space is filled the proper thickness of
lining will be secured. In some cases the
mixture is simply thrown against the
shell in the shape of balls until the lining
is thick enough. To prepare the bottoms,
the hre-clay tuyeres are inserted IN their
places, and the mixture is placed between
them; they are then thrOughly dried in
special oven. Meantime the converter
lining is dried, and is ready for operation.
The operation of basic lining is more
complicated. The limestone, or dolOmlte,
is first burnt at a very high temperature,
so that il shrinks to nearly half of its
original size, and comes out OF the furnace
or cupola where it has been calcined in a
CLASSY state. 1t is then broken and pull
veriZed. and mixed with anhydrOus tar,
so as 10 make it cohesive. In some works
this mixture is made into bricks which
fit the shape of the converter, and are
built into it like wall. In other places
it is rammed between the shell and
mould, as with the acid mixture. Fire
clay tuyeres are also used in the bottoms,
and the shrunk dolomite mixture is
rammed with hot rammers in the inter-
walls.
In the Bessemer process the pig is
melted in a separate cupoIa furnace and
run into the converter, which lies on Its
side. to prevent the metal from running
out Of the tuyere-holes in the bottom.
The blast is then laid on and the vessel
made to stand straight. The air. entering
at a pressure of twenty to twenty-five
pounds per square inch, penetrates the
melted mass. Within a space of about
eight feet in diameter ten-tOn charge is
pierced by no less than 230 to 800 air. Jets,
that bring the oxygen it contains in close
contact with the iron and It's impurities.
These impurities, being already III an in
candescent state, are quickened into rapid
combustion by the powerful blast, as
bellows blowing cold air forces the glow
ing Goals into Il consuming hame. In the
acid operation the only impurities to be
burned away are silicon and carbon;
their rapid combustion causes an eleva-
ton Of temperature, which makes 1t pos
slble for the remaining decarburized iron
to remain fluid until the operation OF
casting into molds is complete.
1t will thus be seen that the so-called
impurities are necessities as well, since
they furnish the full need to carry the
process to a successful end. At the be-
ginning of the blowing, only sparks and
a little brown smoke are seen; the silicon
IS burning, and as the product Of its COM
bustion is solid, viz, silica, which re-
mains as a Stag in the vessel, no namo IS
visible, but only such light solid particles
of Stag as may be carried out by the
strong blast In proportion as the silicon
becomes exhausted the oxygen turns its
diately announced by the appearance of a
true flame, which grows rapidly until it
fills completely the mouth of the con-
verter, and dazzles the spectator by its
brilliancy. The temperature rises
quickly; the flame becomes fuller,
clearer; the metal, stirred by the heavy
blast, boils, and particles of it are ex-
pelled from the vessel the roar of the
flame becomes deatening; the projections
of metal become frequent; and TO one un-
accustomed to the spectacle it would seem
that a continuance of the proceedings
must wreck the entire establishment.
But the carbon is soon exhausted, and
with scarcely an admonitory sign the
flame drops and almost disappears. In
the acid process this is critical moment,
for there is nothing left to burn in the
vessel but the iron, and this would soon
take place to damaging extent. as shown
by the cloud of brown smoke which al
most Immediately follows the drop of the
flame. The vessel is turned down lmme-
diately and the blast shut oil. There IS
in the converter at that moment bath of
decar buried iron, but OxldlZed to such
degree that it is of doubtful usefulness,
as it would probably crack in the rolls.
1t is at this juncture that manganese plays
its friendly role. Spiegelelsen Is intro
duced in a melted state, and gives up to
the bath the carbon it contains, while its
manganese offers itself as sacrifice by
calling to itself the oxygen which con-
taminated the iron. The charge is then
ready to be cast into ingots.-R. X. Bow
ker in Harper's Magazine.