IMPROVEMENTS IN THE MANUFACTURE OF IRON AND STEEL, AND IN APPARATUS USED THEREIN
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by George Hatton at the Office of the
Commissioners of Patents on the 2nd October 1883.
"
GEORGE HATTON, of Hagley in the County of Worcester, iron manufacturer,
IMPROVEMENTS IN THE MANUFACTURE OF IRON AND STEEL, AND IN APPARATUS
USED THEREIN
"3
This invention relates to those processes in the manufacture of Iron and Steel
wherein molten pig iron is deprived of its silicon and carbon and other impurities
by oxidisation, and is thereby converted into soft steel or ingot iron, or, by the
subsequent addition of spiegeleisen or other metal alloy in varying quantities, into
the harder qualities of steel.
Hitherto the two most generally adopted processes are, 1** The Bessemer
process, wherein atmospheric air is blown through molten pig iron until the whole
of the silicon and carbon are removed, in which process the final changes takes place
so rapidly that in making the softer qualities of steel and ingot iron much
irregularity of result is experienced; and, 2nd The open-hearth or Siemens-
Martin process, wherein molten pig iron is deprived of its silicon and carbon, by
prolonged exposure in the hearth of a Siemens furnace, to a process of burning
out the silicon and carbon by contact with the gases of the furnace, and also, when
desirable, by repeated additions of oxide of iron to such molten pig iron; in either
of which cases the process is slower and more expensive than the Bessemer,
though more regular and reliable in its results.
The object of this invention is to secure the rapidity of the Bessemer process, in
the earlier stage of the conversion, with the greater deliberation and reliability of
the open-hearth or Siemens Martin process, in the latter stage or completion of the
conversion.
The process which I employ according to this invention consists, in treating
molten pig iron, first by blowing air through it, until the silicon and the greater
portion of the carbon are removed, and then completing the process after the
manner of the open-hearth or Siemens-Martin, or other process in which the metal
is subjected to the action of flame arising from the introduction of inflammable
gases above the surface of the metal under treatment.
The apparatus which I employ in carrying out my process consists of a chamber
(corresponding to the hearth of the Siemens regenerative furnace employed in the
open-bearth or Siemens Martin process) heated by means of flame either from gas
upon the Siemens regenerative principle or in other convenient manner, such
chamber having a suitable tapping hole and doors for charging and other purposes,
as in the case of the Siemens-Martin furnace. This chamber is connected at one
end or side to the flues for supplying the flame or gas and carrying off the products

page_text: of combustion, and this connection is effected in such a manner as to be readily
broken and re-made for the purposes hereinafter explained. The opening in the
chamber which communicates with the flues, may, if desired, be divided by means
of a mid-feather wall for the better conduction of the flame or gases into and from
the chamber. The chamber is mounted upon trunnions or otherwise supported so
as to be capable of being readily moved or partially rotated in a vertical plane.
Tuyeres are inserted in the lining of the chamber at one end or side thereof so as
to come below the molten metal when such chamber is partially rotated or turned
up as presently explained.
In carrying out my process with the apparatus described, I first place the
chamber in a horizontal position, with the one end or side connected to the flues
aforesaid. The chamber is then heated as before explained and pig iron, either cold
or previously melted, charged therein. As soon as the pig iron is melted (by the
action of the flame) or immediately after the molten iron is charged therein, as the
case may be, the flame or gas is shut off and blast turned on to the tuyeres, and the
chamber is partially rotated or turned up so as to bring the tuyeres below the surface
of the metal, the connection with the flues being consequently at the same time broken,
and the open end or part of the chamber (previously connected with the flues)
now forming the mouth of the chamber through which the waste gases pass off
into the atmosphere. The chamber is kept in this elevated position and the
blowing continued until nearly but not quite all the carbon has been removed from
the iron, at which stage the chamber is turned back again into its horizontal
position, in which it received the charge, and with its mouth again in connection
with the flues. The tuyeres are thus brought again into position above the surface
of the metal and the blast is shut off. The gas and air are now re-admitted into
the chamber through the flues and the process is completed as in the latter part of
the open-hearth or Siemens-Martin process, namely, by a slow process of
oxidisation occasioned by the combustion of the gases within the chamber and, when
desirable, by the addition also of oxide of iron, the small remaining portion of the
carbon and other impurities being thus gradually removed during a much longer
period and consequently with greater accuracy than if the blast process had been
continued to the end. The metal when realy is tapped out into the ladle and
poured into moulds in the usual manner.
In some cases I may prefer to force the air (used in heating) through the
regenerator under slight pressure in order to more thoroughly penetrate to the
farther side or end of the chamber with the flame; and I may prefer, while
retaining the stationary flues, to dispense with the regenerators, and drive. the
gas through into the chamber with air under pressure which may have been
previously heated, in the manner immediately to be described (or in any convenient
manner), namely, thus-when the chamber is. rotated so as to elevate the. mouth,
and the blowing process, is proceeding, the flame and heat escaping from the month
may, be directed through a chamber around a series of pipes contained therein
through which the air for consuming the gas may be passed, and in this manner
heated; and the escaping products from the chamber, during the completion of the
process (after the blowing has ceased) may be conducted around the heating pipes
to maintain the temperature thereof.
Instead of commencing and completing the process in one chamber, the metal
may be transferred from the chamber in which the blowing part of the proces is
conducted, into the open-hearth furnace in which the process is completed.