Improvements in the Manufacture of Iron and Steel.
Year: 1889

page_text: Date of Application, 18th Oct., 1889-Accepted, 30th Nov., 1889
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Iron and Steel.
I, RODNEY FORRest Ludlow, of the City of Springfield, in the County of Clarke,
and State of Ohio, one of the United States of America, Manager Malleable Iron
Works, do hereby declare the nature of my invention and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement :-
This invention relates to an improved method of decarbonizing iron, and liberating
the impurities contained therein, while in a molten state, for the purpose of rendering
the iron in a condition to be recarbonized by fluxing therewith some recarbonizing
agent, to convert it into malleable iron, or wrought iron, or to convert it into
steel.
Before entering into a detail description of my improved method, I desire to
embody herein certain acknowledgements of the state of the art as heretofore
developed, for the purpose of more clearly distinguishing my invention therefrom,
to the end of more strictly complying with the statute relative to distinguishing the
old from the new.
Prior to my invention, atmospheric air has been introduced vertically through a
mass of Molten iron; has been introduced or forced horizontally into the mass ;
has been introduced at an angle, and into the deepest part of the metallic bath; has
been introduced tangentially to and into such mass or bath, and below the surface
thereof, and has been introduced from above at an angle to, and against the surface
of, the molten mass,--in short a molten mass or metallic bath has been acted upon
for the purpose of eliminating the impurities contained therein, and decarbonizing it
by atmospheric air, projected through, among and in contact therewith; and finally
that such mass or bath of iron has been subjected to the air-currents by violently
agitating limited portions only of such bath, while the greater portion was held in a
state of comparative quiescence, in such a manner as to bring every portion repeatedly
within the area of such violent agitation.
My invention differs from each and all of these acts and methods in important,
economical and practical particulars, and, briefly stated, may be said to consist, first,
in decarbonizing the entire mass of molten iron with practical uniformity by constantly
varying the places of contact between its surface and the air-currents projected
against such surface at an angle, or at angles thereto, whereby the whole mass is put
in a practically uniform, regular and constant motion; and secondly, in fusing with
the mass of metal so treated, a quantity of some recarbonizing agent, by mixing
such agent therewith, after the impurities have been eliminated from the mass, and
the iron brought to a decarbonized state. In the annexed diagram, figures 1 and 2,
I have illustrated baths of molten metal, and air-currents acting upon them in
substantial accordance with my invention.
I will now proceed to describe my method more in detail, and the manner of
practicing the same. The molten iron is preferably run off from any of the known
melting furnaces, or otherwise removed from such furnaces, and placed in a vessel
constructed or lined with refractory material to enable it to withstand the heat of the
metal. The depth and other dimensions of this vessel, which may be termed the converter
vessel, will vary with the amount of metal contained in each bath to be decarbonized,
etc., and possibly according to local conditions, and the desire or choice of the
practicer of the method. As it is preferred to remove the dross, scoria, slag or other
impurities which may be found to accumulate on the surface of the bath prior to
the introduction of the recarbonizing agent, I recommend that the converter vessel

page_text: be constructed with an opening at the side, above the level of the bath, through
which suitable skimming tools may be introduced for removing such impurities.
These remarks apply to instances in which the converter vessel at its upper side is too
high from the surface of the bath to render the skimming operation convenient from
over the edge of the converter.
After the inolten metal has been placed in the converter, say to the extent of a
ton, 1 employ any suitable apparatus for directing air-currents upon or against, and
at an angle to, the surface of the bath, and I vary the place of contact between such
currents and such surface so as to extend the places of such contact across practically
the entire surface, embracing more or less of the width of such surface, preferably
from one half to five eights or three fourths thereof, measuring from one side of the
converter vessel toward the other and crosswise to the line of the air blasts. If the
places of contact at the commencement of the operation are established near to
the side of the converter furthest from the side from which the currents proceed,
then the metallic bath will more quickly start in a motion, than if such places of
contact are first established nearer to the side of the converter vessel from which the
currents proceed; the quickness with which the mass of metal responds in motion to
the action of the currents growing less and less as the places of contact grow nearer
and nearer to the blast or current-side of the converter. I also prefer that the angles
between the air-currents and the surface shall vary as the places of contact are
varied, approaching more nearly to a right angle as the places of such contact
approach the current-side of the vessel; though this variance in angle is by no means
a necessity to the successful operation of the method. When the currents are turned
on, and the metal begins to respond to them by assuming motion, the places of
contact are changed by changing the direction of the air currents, or varying the
position of the place from which they proceed, and I prefer to constantly effect this
change, and to not allow the currents to strike a given breast on the surface of the
bath more than a minute or two; thus keeping up a constant change in the places
of such contact. When the places of contact have proceeded across the surface of
the bath in a breast of the desired width, they are then reversed, and the places of
such contact continued step by step back in the opposite direction until such length
of time, (usually from eight to eleven minutes per ton) shall have elapsed, to bring to
the surface the contained impurities, and to liberate or consume the carbon contained
in the bath.
One object in changing the places of contact between the air-currents and the
surface of the bath, progressively back and forth or across such surface, is to ensure
reaching all of the impurities as the particles or quantities thereof come to the
surface at different places, as a result of the general and practically uniform
disturbance of the entire mass, of which no portion is sufficiently quiescent for the
retention of any essential portion or particle of the impurities.
Again, as the places of contact proceed in the direction of the far side of the
converter the impurities which have come to the surface are hastened to said side,
where they more or less accumulate.
I have said that the breast of air-currents was preferably less than the width of
the surface of the bath. I prefer this as it results in giving the bath a rotary motion,
which, if not constant, is more or less intermediate or spasmodic, resulting in a more
thorough agitation of the entire mass, in consequence of the contact of the metallic
currents between the rotary and tumbling tendencies imparted by the air.
What is here described is based upon what has been ascertained by tests on a large
and practical scale of commercial capacity.
The product is either malleable or wrought iron of great textile strength and
ductility, or steel of like strength and fineness of texture.
While any recarbonizing agent may be employed, I prefer to use what is known as
speigeliesen, and to apply it to the bath in a powdered state by throwing a sufficient
quantity thereof into the converter vessel after the impurities have been skimmed from
the surface.

page_text: Having now particularly described and ascertained the nature of my inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :
1st. The berein described method of decarbonizing iron and liberating the
impurities contained therein, the same consisting in disturbing and putting in
practically uniform motion, the essential mass of a bath of molten iron, by constantly
varying the place of contact therewith, of air currents projected against and upon
the surface thereof, at an angle thereto, and in maintaining this operation until the
contained carbon and impurities are liberated, and the latter collected on the surface
of the bath.
2nd. The herein described method of decarbonizing iron, and liberating the
impurities contained therein, the same consisting in disturbing and putting in
practically uniform motion the entire mass of a bath of molten iron by directing
air currents upon and against the surface thereof, at an angle thereto, and in
constantly varying the places of contact back and forth across said surface; in main-
taining this operation until the contained carbon and impurities are liberated from
the iron; in removing the collected impurities; and in putting with the bath
in this condition some recarbonizing agent in quantities to suit the product
sought.
Dated this 18th day of October 1889.
HUGHES, ELI & HUGHES,
76, Chancery Lane, London, W.C., Agents for the Applicant.