An Improved Process and Means for Converting Pig Iron into Malleable Iron or Steel.
Year: 1896

page_text: Date of Application, 14th Aug., 1896-Accepted, 19th Sept., 1896
COMPLETE SPECIFICATION.
An Improved Process and Means for Converting Pig Iron into
Malleable Iron or Steel.
We CHARLES PENROSE SHERK, JAMES LAWRENCE RUTTER, and SAMUEL
WEISS, all of Lebanon, Pennsylvania, U.S.A. Inventors, do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:-
Our invention relates to the method of and apparatus for converting crude or
pig iron into malleable iron or steel, and it has for its object to provide an improved
method and apparatus whereby the usual conversion may be carried out at a minimum
cost, with the least waste of material, and to the best advantage.
To these ends our invention consists in a method of operation, and a construction
of apparatus, substantially such as is hereinafter pointed out.
In the accompanying drawings we have represented the preferred form of
apparatus for carrying out our invention in a manner sufficient to enable those
skilled in the art to understand its essential features of construction and
arrangement.
Figure 1 is a diagram shewing a vertical section of a converter in two positions.
Figure 2 is a horizontal transverse section of the converter on the line of
arrows, Fig. 1.
In carrying out our process we apply the blast of air, used in the conversion of
the metal, so that a portion of the blast enters the metal below its surface, in one
general direction from one side of the converter, and a portion of the blast enters
the converter about the surface of the metal, in another or opposing general direction
from the opposite side of the converter, and by varying the relative relations of the
separate blasts with the surface of the metal by suitable means, as a tilting
converter, we are enabled to vary the application of the blast so as to regulate the
amount applied to the surface of the metal of the bath and the amount injected
into the bath below its surface in accordance with the requirements of any particular
case, so that the action of the different blasts upon the metal may be completely and
perfectly regulated and the baths of varying qualities conditions and compositions
may be converted into malleable iron or steel of the desired quality.
Referring to the accompanying drawings, A represents a converter which may
be of any desired form or type but preferably substantially like that indicated in
the drawings. The converter is shewn as made of three sections A', A2, A3, as we
find this is the most convenient construction and the converter is mounted on
suitable trunnions B, provided with a gear wheel B', which is adapted to be
connected to a hydraulic or other motor by means of which the converter can
readily and quickly be tilted not only in the operation of filling and pouring, but in
the operation of converting the metal. The sections A1 A2 A3 may be joined
together by any suitable means. As shewn, each section is provided at its edges
with a series of perforated lugs I adapted to coincide with corresponding lugs on
the adjacent sections and to receive bolts or other desirable securing devices which
pass through the perforations in the lugs and hold said lugs together.
Arranged at a suitable distance from the bottom of the converter are the
uyeres C, D, E, F, G, which are shewn as passing through the walls of the
converter in a horizontal position, and are, of course to be connected in the usual
vay with the air blast apparatus. In the drawings we have shewn five tuyeres,
and while this is found to be a practical number our invention is not limited to this
recise number, as this number may be varied to suit the requirements of any
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page_text: particular case. It is however important that the tuyeres should be arranged
substantially in the manner indicated, or in an equivalent manner which will
produce substantially the same result. Thus it will be seen that on the pouring
side P of the converter there are a less number of tuyeres than upon the other side
and the arrangement is different. Thus on the pouring side P we have shewn the
tuyeres C, G, and these are arranged at an equal distance from the central line H
passing through the converter in the plane of the trunnions of the converter. Thus
in the drawings the tuyers C and Gare arranged at an angle of forty-five degrees
to the line H. Of course it will be understood that these angles may be varied
somewhat, the angles given being examples of arrangements we have found most
satisfactory, although we have found that similar results, can be attained with a
variation in the angles. On the other side of the converter we have shewn three
tuyeres, tuyere E being arranged at a right angle to the line H and the other tnyeres
disposed at equal angles thereto.
Such being the preferred construction and arrangement of the converter in use
we supply the converter with a suitable amount of molten metal which, if the
converter were in its normal or vertical position, would rise somewhat above the
tuyeres-as, for instance, the line a, but as in practice the converter is usually
tilted or swung downward to receive the charge on its pouring side, the metal does
not at the beginning assume this level. When the charge has been supplied, the
converter is turned up to occupy substantially the position shewn in full lines
in Fig. 1, and the metal will assume a level in the converter on the line b, in which
it will be seen that the tuyeres C and G are below the surface of the metal and on
one side of a plane passing through the trunnions of the converter, while the
tuyeres D, E, F, on the opposite side of the converter are above the line of
metal. In this position the pressure of the air on all the tuyeres being the
same, it will be seen that more air will be admitted above the line of metal from
one side of the converter than below it from the opposite side, and moreover, as
the metal above the tuyeres offers an obstruction to the passage of the air from the
tuyeres there will be a relatively greater amount passing through the tuyeres above
the surface of the metal than below the surface. This is the position we find most
favourable for eliminating the silicon. It will be seen that at this stage of the
process a larger proportion of the air is lowing over the surface of the bath,
while a lesser portion is flowing into the body of the bath, the two portions flowing
from tuyeres in the opposite sides of the converters in opposite directions, and
while the air coming from these last tuyeres will aid in eliminating the silicon it
also performs another important function, and that is to agitate the mass of the
metal and aid in exposing every atom to the air blast, so the mass is more rapidly
and thoroughly desiliconized.
When we find that the silicon has been practically eliminated, it is generally
preferable to tilt the converter to substantially the position indicated in dotted
lines in Fig. 1, in which the tuyeres D, E, and on one side of the converter will
be below the surface, as indicated at the line e while the tuyeres C and G on the
opposite side will be above the surface, and then the operation of eliminating the
carbon and perfecting the conversion is carried out. The degree of tilting and
the time depend, of course, very much upon the character of the charge and the
effect thereon of the air-blast.
It will be understood that by carefully watching the process the operator can
tilt the converter more or less to immerse whichever tuyeres he desires, and, of
course, he can do this at various times throughout the process, for while we have
found the process first described as the most practicable in ordinary charges,
there are circumstances arising which require more or less tilting of the converter
and at different periods of the process. For instance, if it is found that the metal
of the bath is becoming heated too rapidly the converter can be tilted in such
manner as to retard this heating effect and avoid the oxidation of the metal.
When the process of conversion is practically completed, the converter is tilted
in a position to pour the metal and the blast to be cut off.

page_text: While we have thus set forth the general characteristics of our process and the
mode of carrying it out, it will be understood by those skilled in the art that the
details can be varied to suit the requirements of any particular quality or condition
of metal being treated, as it is well known that metals vary in relative proportions
of silicon, carbon, etc., and of course in reducing such metals, different amounts of
oxygen from the air are required at different stages of the process. This can be
thoroughly and practically regulated by the operator in noting the condition of
the gasses escaping from the mouth of the convertor.
We have found that by the use of this apparatus in the manner set forth the
silicon may be thoroughly and quickly eliminated from the metal without injuring
the same, and then the manganese and carbon are eliminated and the metal
thoroughly reduced, when it can be recarbonized to the desired degree. The
metal thus reduced is very uniform in character, every particle being brought
equally and thoroughly under the influence of the blast, which will be mild and
without producing excessive action or oxidation at one portion of the mass of
metal over another, and the condition of the slag can be regulated, so as to make
the process most economical and regular and so that there will not be an excessive
absorption of the recarbonizer of the slag. Moreover at no time need the metal
become overheated or the slag become too fluid, as it is liable to do in the ordinary
processes, as we find that the temperature of the metal may be perfectly controlled
and the danger of oxidising the metal and producing a too fluid slag is prevented.
While we have found under varying conditions more or less of the metal may
be above the tuyeres at the starting, in the drawings we have indicated a converter
adapted to receive a charge of two tons, and the tuyeres are arranged at such a
distance from the bottom of the converter that when the metal is on the line a
about two-thirds of the metal will be below the mouth of the tuyeres and one
third above, and when the converter is tilted to commence the operations the
tuyeres C and G are about midway between the bottom and top surfaces of the
metal, while the tuyeres D and F are substantially parallel to the surface, and
the tuyere E above the surface, and under these conditions we have found the
most favourable results. It will be readily understood that as the lining becomes
worn in the process of conversion these relations will vary somewhat initially, but
they can be compensated for by tilting the converter more or less.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what
we claim is :-
(1.) The hereindescribed process of converting pig iron into malleable iron or
steel substantially as hereinbefore set forth.
(2.) The hereindescribed means for converting pig iron into malleable iron or
steel substantially as herein before set forth and illustrated in the drawings hereunto
annexed.
Dated this 14th day of August 1896
PERCY R. J. WILLIS.