IMPROVEMENTS IN PURIFYING CAST IRON AND CONVERTING IT INTO WROUGHT IRON, AND APPARATUS FOR THAT PURPOSE
Year: 1880

page_text: LETTERS PATENT to John Imray, of No. 28, Southampton Buildings, in the
County of Middlesex, for an Invention of "IMPROVEMENTS IN PURIFYING
CAST IRON AND CONVERTING IT INTO WROUGHT IRON, AND APPARATUS FOR
THAT PURPOSE." A communication from abroad by Lucius Delison Chapin,
of No. 25, Aldine Square, Chicago, Illinois, in the United States of America.
PROVISIONAL SPECIFICATION left by the said John Imray at the Officeo
of the Commissioners of Patents on the 19th February 1880.
JOHN IMRAY, of No. 28, Southampton Buildings, in the County of Middlesex.
"IMPROVEMENTS IN PURIFYING CAST IRON AND CONVERTING IT INTO WROUGHT
IRON, AND APPARATUS FOR THAT PURPOSE." [A communication from abroad by
Lucius Delison Chapin, of No. 25, Aldine Square, Chicago, Illinois, in the United
States of America.]
According to this Invention cast or pig iron is treated as in a converter, by
blowing air through it so as to eliminate impurities, and is then either mixed with
a larger quantity of less pure iron, so as to obtain good serviceable pig from the
mixture, or it is treated or puddled in a rotating or oscillating furnace, so as to
produce balls for the manufacture of wrought iron. The converter may be separato
from the puddling or balling furnace, both of which may be of any known
construction, or, according to this Invention, the same vessel and apparatus may be
made to serve both purposes, the construction thereof being as follows:-A
cylindrical vessel like those used as rotary furnaces, lined with refractory material,
preferably presenting internal ribs or irregularities, is mounted so that it can be
made to revolve or rock on its horizontal axis. Along one side of the vessel, in the
lining thereof, is formed an air channel having a number of tuyere holes opening
from it into the interior of the furnace. At one end the vessel is formed with a
collar enclosed within a stationary hollow ring, from which there opens a side-port,
which, in one position of the furnace, when the air channel is lowest corresponds
with the mouth of the channel, so that when an air blast is sent into the hollow of
the ring the air passes into and along the channel in the furnace lining, and issues
therefrom by the tuyere holes, blowing through the molten metal lying in the
furnace. When the furnace is turned partly round, the tuyere holes being thereby

page_text: brought up towards the surface of the molten metal, the port leading into the
channel is more or less closed, and thus the blast is moderated to suit the less depth
of metal through which it has to pass; or when the furnace is turned still farther
round the blast port is closed altogether.
The ends of the furnace vessel are open,
but provided with doors, and the vessel is mounted between a furnace fire at its
one end and a chimney or flue at its other end. The vessel also has a part of its
side opposite to the air channel hinged, so that it can be opened as a door, and it
has in this door a feeding hole which can be closed by a plug. With a furnace
thus arranged iron is treated in the following manner:-The vessel being turned
to the position where its air-channel is lowest and its feeding hole bighest, molten
iron is run into it, and the blast is turned on and continued until the impurities
are eliminated so far as may be desired, their elimination being promoted by giving
the vessel more or less rocking motion, so as to direct the blast from the tuyere
holes through all parts of the metal. When it is desired to produce good serviceuble
pig from impure iron a portion is first thus purified by the blast, and then a farther
portion being run into the vessel and nixed therewith, the whole may be run out
as good pig. When wrought iron is to be produced the metal is first purified by
the blast, and then the blast being stopped the end doors of the vessel are opened,
so that the reverberatory flame passes through it, and the vessel being then caused
to rotate or oscillate on its axis the metal becomes puddled and balled, and the ball
or balls can be removed by opening the side door, and treated in the usual way for
the manufacture of wrought iron.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Imray in the Great Seal Patent Office on the 16th August
1880.
-
JOHN IMRAY, of No. 28, Southampton Buildings, in the County of Middlesex.
"IMPROVEMENTS IN PURIFYING CAST IRON AND CONVERTING IT INTO WROUGHT
IRON, AND APPARATUS FOR THAT PURPOSE." A communication from abroad by
Lucius Delison Chapin, of No. 25, Aldine Square, Chicago, Illinois, in the United
States of America.
Heretofore in the manufacture of wrought iron from cast iron it has been usual
to effect the conversion of the cast iron into wrought iron by what is commonly
known as the puddling or boiling process. This process, while generally giving
good results, is necessarily slow, tedious, and expensive, and requires skilled labour.
It is also usual in making steel from cast iron to effect decarbonization of the
molten cast iron, and to a certain extent the removal or elimination of other
impurities from the cast iron by the use of jets or blasts of atmospheric air passing
through the molten material. This latter process, commonly known as the Bessemer
process, is rapid in its operation, but has not been found successful in the
manufacture of the common wrought iron of commerce. The present Invention,
stated in general terms, contemplates the combination of the air blast purifying
process of eliminating the carbon, and to some extent also the phosphorus, sulphur,
and other impurities found in cast iron, with so much of the puddling or boiling
process as involves the bringing of the previously converted charge from a molten
condition and while under the reverberatory action of a suitable heat or flame, into
the condition of puddled wrought iron, or a puddle ball ready to be removed from
the working chainber, and subjected to the action of squeezers, hammers, or rolls in
the ordinary manner. The first part of the process, viz., that in which the air
blast is used, is rapid in its operation, and when properly worked gives good
results in the purification and conversion of the iron till it arrives at or approaches
the transition point between the granular and fibrous structure, or, as it is some-
times termed, "approaches nature." The latter part of the process, or that in which
the reverberatory action of heat or flame is employed, completes the conversion of
the iron, and when properly manipulated enables the iron to be brought to
"nature," and balled up with a degree of certainty as to good results. In carrying
out the improved process the molten cast iron, either as it comes from the blast
furnace or as remelted and while enclosed in a suitable converter, is first subjected
to the action of an air blast, such as is employed in the Bessemer process, and in
order that all parts of the molten material may be brought equally within the
influence of the blast the converter, during the action of the blast, is oscillated or
rotated on its axis. This operation is continued, varying the blast if necessary, and
omitting at intervals the oscillatory or reverberatory action, as may be found
desirable, until the iron is sufficiently purified and comes to or approaches "nature,"
or, in other words, to the transition point from the granular condition to the
condition in which on treatment it becomes fibrous. The completion of the process,
that is, bringing it quite to "nature" and balling it, is performed either in the same
converter or receptacle or in any other suitable apparatus, in which the molten
mass is kept in motion while exposed to a reverberatory flame. In carrying out
the process various kinds of apparatus may be employed, but the accompanying
Drawings illustrate a construction which is considered suitable for operating, as
will now be described.
Fig. 1 is a perspective view of a rotative converter shewn, with its side door
open; Fig. 2 is a perspective view of the same with the side door closed; Fig. 3 is
a longitudinal section; Fig. 4 is a transverse section on the line ---x of Fig. 3;
Fig. 5 is a transverse section on the line y -- -y of Fig. 3, and Fig. 6 is a side clevation

page_text: to a reduced scale shewing the arrangement of the converter in conjunction with
the furnace and chimney.
In carrying out the first part of the process iron either as it comes from the blast
furnace or pig iron remelted is treated, but it may be assumed to be common iron of
ordinary or average quality as it comes from the blast furnace and without
remelting. Such iron is treated in a converter A of any suitable form or
construction, but preferably of a cylindrical or barrel shape made with closed ends,
or if the ends be open they are provided with doors n, n'. This converter A is
arranged to revolve or oscillate on a horizontal axis. For the supply of air in jets
under pressure there are tuyeres a opening from a tuyere box or channel A¹ and
distributed along the whole length of the converter. The air under pressure may
be introduced from any suitable pump or reservoir to the tuyere box and tuyeres
through the trunnions of the converter when it has closed ends or when the ends
are open through a stationary ring B, which encompasses one neck of the converter,
and in which there are ports or passages 6 for the introduction of the air. The
amount of air supplied may be regulated in any known way as by a cock or valve
opened or closed more or less; but in order that the air supply may be at its
maximum when the tuyeres are in their lowest position and be gradually cut off as
the tuyeres approach the upper level of the molten metal in the converter, the
passage bis made with a port c corresponding with a port a¹ opening into the
tuyere box, the length of this port c being such that when the converter is rotated or
oscillated the port a' is gradually cut off, but not entirely closed until the mouths
of the tuyeres come about to or a little above the level of the molten metal in the
converter. The molten metal being run into the converter the air blast is turned
on, and an oscillatory or rotary motion is imparted to the converter during the
operation of the blast so that all parts of the molten metal may be acted upon by
the air. When the temperature becomes too great the quantity of air admitted may
be lessened or the tuyeres may be brought above the level of the molten metal.
In this way, that is, by bringing the air blast to act throughout the entire mass of
the iron, and by automatically or otherwise varying the air supply as the temperature
varies the various impurities of the iron are removed, since it is a well known fact
that different impurities are more quickly eliminated at different temperatures ;
and the object of the blast is chiefly to remove or eliminate the impurities ordinarily
present in the cast iron, particularly phosphorus, carbon, sulphur, and silica. The
converter may receive the rotary or oscillatory motion in any known manner; for
example, it may rest on friction rollers & and be driven by steam or other power
communicated through gearing d, d². The converter itself may be made of any
suitable material, such as an iron casing lined with firebrick or other refractory
substance capable of sustaining a high heat, and when bricks are used they may be
laid alternately flatwise and edgewise, or if other lining material is used it may be
laid in layers alternately thin and thick so as to form a number of inwardly
projecting ribs c which facilitate the agitation of the molten mass. If desired, the
weight of the tuyere box and tuyeres may be counterbalanced so that the converter
may be rotated or oscillated with equal caso in any attitude. The converted may
be charged through a charging hole in its side or through one of the end doors n'.
There is also a door D extending nearly the whole length of the converter for the
removal of puddle balls, as will presently be described. The rotating or oscillating
movement of the converter is kept up, with perhaps occasional intermissions,
according to the temperature and the amount of iron under treatment, but for the
most part faster or slower while the blast is blowing, until the impurities are
eliminated, which in ordinary cases will occupy about fifteen minutes to bring the
iron to "nature" as it is ternied. It is generally advantageous to stop the operation
a little short of that point, such point being determined, as well as other points or
stages of impurities, by the colour of the flame in the elimination, or by other known
means. In order now to complete the conversion of this material into wrought iron
it is brought quite to "nature" by any one of the several methods of balling, each of
which involves the use of inechanical motion imparted to the molten mass, and the

page_text: application thereto of a reverberatory flame until the particles become agglutinated
and the mass can be formed into puddle balls. One mode is to bring the iron to
"nature" and ball it in the converter itself, in which case the ball will be formed
nearly as long as the inside of the converter. In order to remove it with facility
the door D is made in one side, preferably opposite the tuyeres, nearly as long as
the chamber, and sufficiently broad to permit the ball to fall out when the converter
is turned with this side opened downwards. The end of the converter may be so
arranged as to be easily reinoved, and in that case the ball can be removed from
the end. When the converter is in operation the door D or that at the end is
closed and secured by any suitable fastening, but there is a hole by which the
molten iron may be first introduced, shewn as closed by a stopper D', so that as the
work progresses the operator may be able to judge from the colour or appearance
of the escaping flame of the progress of the work. The converter when it is to be
thus used is made with open necks and combined with a fire chamber of a rever-
beratory furnace, as represented in Fig. 6. H is the fire chamber, having a side Blue
opening into one end of the converter, and a top flue opening into a chimney H¹.
The other end of the converter opens into a flue leading to a chimney H². It is of
advantage to make the opening from the fire chamber a little larger than the other.
The iron having been sufficiently purified and brought nearly to "nature," as above
described, the air blast is stopped (except so far as it may be necessary to continue
it for protecting the tuyeres, for which purpose steam may be used), and the doors n¹
being opened the material is subjected to the action of the reverberatory flame of
the furnace H, whereby the conversion of the iron is completed, bringing it fully to
"nature," or the desired condition for halling it ready for the rolls or squeezers.
This operation differs in no very material respect from the ordinary balling opera-
tion. The mechanical motion which is necessary is provided for by continuing fast
or slow, as may be found necessary, the rotary or oscillatory motion of the converter,
intermitting such motion or varying the speed, as the condition of the material and
the progress of the work may require. The one door n may be used to exclude the
reverberatory flame while the purifying operation is in progress, the other door n¹
being opened for the escape of gases and after the purifying operation is completed,
both doors may be opened in order that a reverberatory Blame may be applied, as
described, for converting and balling. These doors may also be used as dampers to
regulate the draft by partially opening or closing either or both at intervals as the
work inay require. These doors may be made as slides working in dovetailed guides e
or in other convenient manner. A damper should be provided in the chimney H¹,
so that inore or less of the furnace flame may be sent through the converter or
permitted to pass up the chimney H¹ according as the slide is wholly or partially
open or closed. Instead of the slides n, n¹, other suitable doors may be employed
for the ends of the converter, and modifications might be made in the construction
of the converter and arrangement of the furnace for producing the heat employed
in the balling operation, it only being essential that such heat shall operate with a
reverberatory action on the material to be treated. Hot air or a hot flame of any
kind, or even steam as a modifying agent may be used, provided it has the necessary
temperature, and that it is chemically such as is required by the work to be done
by the reverberatory action.
In the manner thus described the iron is brought fully to "nature" and balled,
after which it is removed and further worked in any known manner. Excess of
cinder may be run off through the stopper hole or cinder taps, scrap iron, manganese
or manganesian lime stone, or other inaterial may be introduced into the iron at
any desired stage of the operation. The structure and operation thus far described
relate for the most part to the working of the Invention when the purification,
conversion, and balling of the iron are all done in the same converter or working
chamber. The first part of the operation, namely, the purification and bringing
nearly up to "nature," may be performed in the converter described, and in the
manner described, or in a converter with closed ends having no connection with a
reverberatory furnace. In such case other means are employed for completing the

page_text: "
conversion of the iron, bringing it entirely to "nature," and balling it. For
example, the contents of the converter are run off into another apparatus, the
duplicate of the converter, with the exception that it has no tuyere box or other
air blast supply, being simply a cylindrical shaped revolving reverberatory furnace,
with open ends, connected with a fire place and flue, and made to rotate as described
when the converter itself is used for balling, the ball being in such case removed in
the same way. Or the contents of the converter may be run off into a puddling
furnace and stirred while subject to the furnace heat, and balled by ordinary
mechanical appliances.
Ordinarily in this part of the process no boiling or puddling operation is
performed, but the treatment of the molten mass in the converter may be arrested
at a lower stage, so that it will to a limited extent be puddled or boiled after it has
been run into the puddling furnace. When the ball is formed, it is transferred to
the squeezers, hammers, or rolls, and worked into bar in the usual way. Another
mechanical means of giving motion to the metal after coming from the convorter, is
by the use of a circular tilted basin caused to rotate on a nearly perpendicular axis.
The metal is run from the converter into such a basin, and subjected to the required
heat. For this purpose blast furnace or other gas or heated air may be blown
through a pipe in the centre of the basin, terminating in a series of goose necks,
downwardly bent so as to deflect the hot air or gas on to the surface of the iron,
or a flame may be made to pass over the basin as in an ordinary puddling furnace.
After the charge has been introduced into the basin, it should be covered so as to
prevent loss of heat by radiation, and the bottom and sides of the basin should also
be protected by a suitable casing. By rotating the basin the granulated or spongy
portions of metal become gathered into a puddle ball, which can be removed and
operated on as usual. Obviously a furnace, such as that known as the Danks' or
other similar furnace, having a reverberatory action, may be used in this last stage
of the operation, that is to say, the material may be run from the converter after
being purified directly into such a furnace, brought to " nature," and balled in the
known manner. Other known mechanical means may be used for balling by
subjecting the metal to the reverberatory action of heat while motion is imparted
to it. For different qualities of pig iron, it is necessary to vary the amount and
force of the air blast used in effecting its purification, according to the known rules
governing such variations. The form and construction of the converter may
obviously be varied, provided it be fitted for rotating or oscillating on an axis
horizontal, or nearly so, during the whole or greater part of the time when the
blast is in operation, so that the entire mass of iron may be thoroughly or effectually
purified. The particular advantages resulting from the process described are, first,
dispensing with the ordinary puddling or boiling operation, which is slow and
costly; secondly, the production of superior quality of wrought iron with a
greatly reduced amount of labour, and consequently greatly reduced expense. For
most purposes the oscillating motion during the purifying process is to be preferred.
This oscillating motion may be obtained from a crank or other mechanism producing
reciprocation. Instead of running the molten metal direct from the blast furnace
into the converter, the pig iron may be remelted in a cupola or other suitable
furnace, and run from it into the converter; also a portion or the whole of the pig
iron may be melted in the converter itself. The purified metal may be run from
the converter direct into a sand bed, in which case, if the treatment with air has
been carried nearly to the extent of bringing the iron to "nature," the product will
be porous pig, having some of the features of iron sponge, and this product can be
charged into an ordinary puddling furnace, remelted or heated, and puddled and
brought to "nature" and balled in a comparatively short time, so as to save a great
part of the entire work and time and waste of puddling or boiling. If the air
treatment is discontinued sooner, a little longer time will be required in puddling or
boiling, but in any case the time and labour of the whole process will be greatly
lessoned.
In describing the application of this Invention relating to the purification of cast

page_text: iron, it may be stated that usually the iron employed for foundry castings is no
better in quality than the pig from the blast furnace, which is often so impure that the
castings from it are very imperfect, and sometimes even worthless. The object of
this process applied to cast iron is to greatly improve its quality, which is effected
by the use of the converter, as already described in the process of making wrought
iron, so far as the purification is concerned, with this difference however, viz., that
the degree to which the purification is carried is to be varied according to the purpose
to which the product is to be applied. After the purification has been carried to
the point desired, the slag is run off, and the tuyeres are held above the surface of
the metal. There is then introduced into the converter, preferably molten, but it
may be solid or heated, the kind and amount of iron required of suitable quality,
and when this is mixed with the purified iron in the converter, the contents are
run off into a sand bed in the condition of purified pig. Or the charge may be
retained in the converter, put under the influence of the reverberatory heat as if for
balling, and thus retained in a condition of fluidity suitable for casting, so that it
runs from the converter as from a cupola into the moulds prepared for it. It is to
be observed that in this process, there are three qualifying elements :-
First. The degree of purification.
Second. The iron to be subsequently introduced.
Third. The ratio of this introduced iron to the previously purified iron.
The variations in these three elements to meet the particular purpose in every
case are to be determined by experience. If the casting is to be firm, strong, and
soft, common pig is submitted to the air blast from eight to twelve minutes, more
or less, according to the nature of the iron, the condition of the atmosphere, and the
force of the blast. The slag being then removed and the tuyeres raised above the
surface of the metal, the iron to be mixed is introduced, preferably in molten form,
and the better the quality of the iron thus introduced the better the result. The
amount of iron thus introduced will be approximately in the ratio of two parts to
one of the purified iron. After sufficient mixture the mass may be run into the
sand bed, for purified merchantable pig, or put under the reverberatory heat and
transferred to moulds for casting. In the same way iron of a greatly superior
quality may be prepared for malleable and chill castings. In these cases the
purifying process is to be carried further than for making soft castings, and thus
iron cheaper than that usually employed for malleable purposes is economically
produced. If the castings are to be exceedingly strong, hard, and of steel like
quality the purification by the air blast is carried to nearly the same extent as for
making wrought iron (nearly to "nature"). There is then introduced into the
purified metal a suitable proportion of fine manganese, or speigeleisen or other high
carburet of iron in molten form, care being taken to keep the tuyeres always above
the surface of the iron after the purification has been finished. The reverberatory
hent is then applied to keep the mass in a fluid condition until it can be transferred
to the moulds, or, if desired, to the sand bed, for hard pig. The advantages of this
process of purifying iron are:-
First. The great improvement of the quality of cast iron.
Second. It permits the use of ordinary and impure pig for good castings, by
first purifying it, and then, if so desired, introducing into it a percentage of pig of
better quality.
Third. It provides means of making a hard-coal and coke iron a better material
for malleable castings than expensive cold blast charcoal iron, and of making a
cold blast charcoal iron much better than before.
Fourth. It provides means of introducing into the manufacture of car-wheels and
other chilled castings a large percentage of common iron without vitiating the
result, and with greatly enhanced economy, and
Fifth. It provides means of obtaining at small cost, and in any suitable foundry,
the best possible strong hard castings for agricultural and other purposes demanding
material of this kind.
Having thus described the nature of this Invention, and in what manner the

page_text: same is to be performed, as communicated to me by my foreign correspondent, I
claim,―
First. The method of making wrought iron by subjecting molten pig simul-
taneously to the oscillatory or rotary action of a converter, and to the action of an
air blast until it is sufficiently purified and approaches "nature," and then bringing
it to nature and balling it by the means and in the manner substantially as
set forth.
Second. The method of preparing iron for subsequent reworking, by subjecting it
to the simultaneous action of an air blast, and the rotary or oscillatory action of a
converter, and arresting the action of the blast on the iron as it approaches "nature,"
and running it off into a sand bed, thereby producing a porous pig, capable of being
brought fully to nature with little or no puddling or boiling, substantially as
described.
Third. The use for operating in the manner referred to in the preceding claims
of a rotary or oscillatory converter furnished with a lateral system of air blast
tuyeres, in combination with means for the introduction of a reverberatory flame
through the end of the converter, and suitable valves or dampers for regulating
such reverberatory flame, substantially as described.
Fourth. In a converter of the kind above referred to, the combination of the
ring B', and its air passage, with the air passage to the tuyeres and the ports of the
said passages, substantially as described.
Fifth. The process of purifying cast iron by means of the air blast, mixing with
it other forms of pig, and retaining the mixture under reverberatory heat until it
is run out for casting.
In witness whereof, I, the said John Imray, have hereunto set my hand and
seal, this Sixteenth day of August, in the year of our Lord One thousand
eight hundred and eighty.