IMPROVE- .MENTS IN THE MANUFACTURE OF MALLEABLE IRON AND STEEL, AND IN APPARATUS USED IN BUCH MANUFACTURE
Year: 1868

page_text: LETTERS PATENT to Henry Bessemer, of Queen Street Place, Cannon
Street, in the City of London, for the Invention of "IMPROVE-
.MENTS IN THE MANUFACTURE OF MALLEABLE IRON AND STEEL, AND IN
APPARATUS USED IN BUCH MANUFACTURE."
Sealed the 21st July 1868, and dated the 21st March 1868.
PROVISIONAL SPECIFICATION left by the said Henry Bessemer at the
Office of the Commissioners of Patents, with his Petition, on the
21st March 1868.
I, HENRY BESSEMER, of Queen Street Place, Cannon Street, in the
City of London, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN THE MANUFACTURE OF MALLEABLE IRON AND STEEL, AND IN
APPARATUS USED IN SUCH MANUFACTURE," to be as follows:-
These improvements relate, firstly, to the manufacture of malleable
iron and steel from crude molten iron, from remelted pig iron, and
from cast scrap or other carburets of iron by means of certain modi

page_text: fications of or additions to the Bessemer process of making malleable
iron and steel, such modifications or additions having for their chief
objects the production of cast steel by a more complete purification
of the cheap or inferior kinds of pig or cast iron, and the employment
and admixture with such purified inferior iron of molten iron of a
more pure or better quality, such as is now generally employed in the
Bessemer process.
In carrying my said improvements into practical operation I prefer
to employ a converting vessel made of stout plate iron, the vessel being
flattened on the two sides where the trunnions are formed. These
trunnions I prefer to make of cast iron, having large ribbed flanges
formed thereon by means of which they are securely fastened to the
sides of the vessel which is much strengthened thereby. The con-
verting vessel is provided with two tuyere boxes placed at about one-
fourth of a circle from each other, so that if the tuyeres in these
separate boxes be directed to a point coincident with the trunnions of
the vessel they will be nearly at right angles to each other. That
part of the vessel into which the tuyeres from each box are directed
may be hollowed out or formed into a cavity or hearth, or the tuyeres
may simply enter the general curved surface of the interior of the
vessel. I however prefer to form two cavities or hearths separated by
a sort of low mound between them formed of ganister or other
refractory material with which the vessels are usually lined; by way of
distinction I will call the first or small hearth A, and the second or
larger hearth B. The first hearth may if found desirable be lined or
"fettled" with "bull dog," or with "red ore," as in puddling furnaces,
while the rest of the vessel is lined by preference with ganister. The
vessel is provided with suitable openings as usual for putting in
the fire-clay tuyeres, and also with other openings at the sides for the
introduction of an iron bar to lift up or stir the charge if necessary.
In some cases I also provide other openings for the insertion of tuyeres
or nozzles for the purpose of injecting certain fluids into the metal
when found desirable and which will be herein-after referred to. The
vessel is further provided with a large opening or mouth for receiving
and discharging both the metal and the fuel employed to heat the
vessel.
The trunnions of the vessel are so arranged that air or steam may
send through or around them and by means of suitable branch

page_text: pipes be conveyed into the tuyere boxes as required. The vessel may be
moved on its trunnions by hydraulic apparatus, as at present practised,
or by a small engine acting on suitable gearing in connection with the
trunnions.
The converting vessel having been heated by blowing up a coke
fire as usual therein and the residue of the fuel turned out the vessel
is to be turned into a position suitable for receiving the fluid iron.
Some "mill scales," "hammer slack," "red ore," or any other matters
that have hitherto been found desirable to use in puddling iron may
be put into the hearth A, and then a charge of molten iron of a cheap
or inferior quality may be run in; a blast of air or steam is then
turned on through the tuyeres into the small hearth A, and the vessel
turned up so as to cause the molten metal to run into the hearth and
be operated upon by the blast. It must be understood that the
tuyeres in the small hearth A are of a smaller size and are less in
number than is usually employed in the Bessemer process.
As soon
as the iron is somewhat raised in temperature the workman by means
of a suitable valve will turn on steam with the air, or he will use
steam alone. The result of the partial decarbonization of the metal by
the slow action of a restricted supply of air and the cooling effect of
steam operating with the mill scales and other matters will tend to
convert the metal into a pasty or granular mass mechanically mixed
with fluid cinder. The constant and somewhat violent heaving up of
the mass by the jets of air or steam tends to divide the metal and
disseminate it in a more or less granular form throughout the fluid
cinder. Additions of mill scale, iron ore, oxide of manganese, or other
substances used to form puddling cinder may be added as thought
desirable, and if the mass becomes too stiff an iron bar may be intro-
duced at the openings before named, and the metal thereby raised
and divided; meantime the use of stem may be discontinued and
replaced by a blast of air which will rapidly restore the temperature
necessary to carry on the process. The management of the heat and the
employment of air or steam from time to time will thus be left to
the judgment and experience of the operator, who will judge of the
state of the metal partly by the heavy sound of the escaping blast
as it heaves up the metal, and also by the condition of the flame and
sparks emitted from the mouth of the vessel. As soon as the workman
judges that the process has been carried far enough he will turn down

page_text: the vessel and run therein a charge of molten iron from a neighbouring
melting furnace, the iron so added may be a good grey haematite or
some other good quality of iron, preferably containing a little man-
ganese and sufficient carbon; he will then turn up the vessel so far
that both portions of the metal will run into the second or larger
hearth B, where the tuyeres are larger and more numerous than in
the first hearth, so that a powerful blast of air may be driven through
the metal and increase its temperature and completely melt the first
charge and unite therewith; the metal may then be run from the
vessel into a ladle in the state of steel, but I prefer to entirely
decarbonize the double charge of metal before running it from the
vessel and add thereto a known quantity of manganesian pig iron in a
fluid state as commonly practised in making Bessemer steel.
Although I have herein described how the first portion of the charge,
consisting of an inferior iron, may be purified by a process similar in
its effects to the process of puddling, I desire it to be understood that
the first portion of the charge may be in part decarbonized and
refined by forcing into the fluid metal jets or currents of fluid
nitrates of soda or nitrates of potash, or other fluid matters containing
or capable of evolving oxygen when brought in contact with molten
iron by means of tuyeres or nozzles. In order to prevent the rapid
wear of furnaces employed in fusing malleable iron or steel on the
hearth of such furnaces I construct the roof and parts most exposed
to heat with hollow bricks or with passages between them, through
which I pass a current of air to keep down their temperature, and
I also utilize the heat so abstracted by using the heated air to sustain
combustion in such furnaces.
Secondly. My Invention consists in applying the combined action
of furnace heat with the heat developed by jets or currents of air
forced into fluid iron when applied to mixtures of solidified iron or
steel with molten carburets of iron for the purpose of fusing such
solid portion and for decarbonizing the same so as to produce from
such mixed materials fluid malleable iron or steel.
Crude or pig iron of an inferior quality may be more or less purified
by puddling, and either in the state of malleable iron or puddled steel,
and in a loose granular condition, or as puddled balls, may be removed
. to another suitable furnace; or it may be treated in the furnace in

page_text: which the puddling process has been carried on. Some molten iron
in either case is then added and a blast of air is driven up through
the metal, raising its temperature and causing by its joint action with
the furnace heat the solid portions of the charge to fuse and blend
with the rest and pass into the condition of molten malleable iron or
steel. When tapped from the furnace it may be mixed with spiegel-
eisen or ferro-manganese, and then formed into ingots or other
castings.
I also employ the same combined action of jets of air and furnace
heat for the fusion and conversion of wrought scrap iron of any kind
and other masses of wrought iron, such as old iron, railway bars, and
also any steel scraps, sculls, spillings, and crop ends of steel rails or
forgings.
I prefer to employ for the purposes of this second part of my In-
vention a reverberatory gas regenerative furnace or other gas furnace
in which heated air and gas are used.
The jets or currents of air may be forced into the molten metal
through moveable pipes or tuyeres, but I prefer to employ fixed
tuyeres made of fire-clay and to stop up or cover over the ends
thereof with fire-clay, loam, or ganister previous to turning on the air,
the stopping being removed with an iron rod or by the pressure of
the air, as may be found most convenient.
This mode of treatment is also applicable to iron which has been
more or less purified or rendered into steel or malleable iron by the
action thereon of nitrate of soda, or nitrate of potash, or other
substances which yield oxygen on coming in contact with molten iron.
Should such metal have become solidified wholly or partially I render
it again fluid by mixing with it molten pig irou in a furnace heated
by fuel, and I also force jets of air into the flued portion of the
mixture. Or the process may be conducted in the vessel in which
the nitrates or similar substances were applied, the fire, heat, and air
jets being used in this vessel.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry Bessemer in the Great Seal Patent Office
on the 21st September 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
BESSEMER, of Queen Street Place, Cannon Street, in the City of London,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-first day of March, in the year
of our Lord One thousand eight hundred and sixty-cight, in the thirty-
first year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Henry Bessemer, Her special licence that I,
the said Henry Hessemer, my executors, administrators, and assigns, or
such others as I, the said Henry Bessemer, my executors, administrators,
and assigns, should at any time agree with, and no others, from time to
time and at all times thereafter during the term therein expressed, should
and lawfully might make, use, exercise, and vend, within the United
Kingdom of Great Britain and Ireland, the Channel Islands, and Isle of
Man, an Invention for "IMPROVEMENTS IN THE MANUFACTURE OF MALLEABLE
IRON AND STEEL, AND IN APPARATUS USED IN SUCH MANUFACTURE," upon the
condition (amongst others) that I, the said Henry Bessemer, my
executors or administrators, by an instrument in writing under my,
or their, or one of their hands and seals, should particularly describe
and ascertain the nature of the said Invention, and in what manner the
same was to be performed, and cause the same to be filed in the
Great Seal Patent Office within six calendar months next and imine-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Henry Bessemer, do hereby declare
the nature of the said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by
the following statement thereof, that is to say :-
These improvements relate, firstly, to the manufacture of malleable
iron and steel from crude molten iron, from remelted pig iron, and from
cast scrap or other carburets of iron by means of certain modifications
of or additions to the Bessemer process of making malleable iron and
steel, such modifications or additions having for their chief objects
the production of cast steel by a more complete purification of the

page_text: cheap or inferior kinds of pig or cast iron, and the employment and
admixture with such purified inferior iron of molten iron of a more
pure or better quality, such as is now generally employed in the
Bessemer process.
In carrying my said improvements into practical operation I prefer
to employ a converting vessel made of stout plate iron, the vessel being
flattened on the two sides where the trunnions are formed; these
trunnions I prefer to make of cast iron, having large ribbed flanges
formed thereon, by means of which they are securely fastened to the
sides of the vessel which is much strengthened thereby. The converting
vessel is provided with two tuyere boxes placed at about one-fourth of
a circle from each other, so that if the tuyeres in these separate boxes
be directed to a point coincident with the trunnions of the vessel they
will be nearly at right angles to each other. That part of the vessel into
which the tuyeres from each box are directed may be hollowed out
or formed into a cavity or hearth, or the tuyeres may simply enter the
general curved surface of the interior of the vessel. I however prefer
to form two cavities or hearths separated by a sort of low mound
between them formed of ganister or other refractory material with
which the vessels are usually lined; by way of distinction I will call
the first or small hearth A, and the second or larger hearth B. The
first hearth may if found desirable be lined or "fettled" with "bull
dog," or with "red ore" as in puddling furnaces, while the rest of the
vessel is lined by preference with ganister. The vessel is provided with
suitable openings as usual for putting in the fire-clay tuyeres, and also
with other openings (n) at the sides for the introduction of an iron bar
to lift up or stir the charge if necessary. In some cases I also provide
other openings for the insertion of tuyeres or nozzles for the purpose of
injecting certain fluids into the metal when found desirable, and which
will be herein-after referred to. The vessel is further provided with a
large opening or mouth for receiving and discharging both the metal
and the fuel employed to heat the vessel.
The trunnions of the vessel are so arranged that air or steam may
be passed through or around them, and by means of suitable branch
pipes be conveyed into the tuyere boxes as required. The vessel may be
moved on its trunnions by hydraulic apparatus, as at present practised, or
by a small engine acting on suitable gearing in connection with the
trunnions.

page_text: In order that the construction and arrangement of the several parts
of the converting vessel may be fully understood I have represented
the same on the Sheet of Drawings hereunto annexed, where Figures 1,
2, and 3 are vertical sections on the line C, D, of Figure 5. The vessel
is shewn in side elevation at Figure 4 and in vertical section at Figure 5,
the section being taken on the line E, F, of Figure 4; an end elevation is
also shewn at Figure 6. In these several Figures a represents the outer
shell of the vessel made of wrought-iron plates, and b, b, are the cast-
iron ribbed trunnion plates secured to the sides of the vessel, a part of
this casting at 6* being formed into a hollow axis or trunnion on which
the vessel is supported, and on which it moves in suitable bearings c
formed on the standards c*. The vessel is lined with ganister or other
suitable material throughout, as shewn at d, or a part of it may be lined
or "fettled with "bull dog," "red ore," or other materials used to line
or "fettle" puddling furnaces. The vessel is so formed internally as
to divide its interior into two hollows or hearths A and B, the lining
being raised at d* so as to form a low mound or division between them;
each of these hearths is provided with tuyere boxes, the hearth A having
a tuyere box e with fire-clay tuyeres r, shewn also in plan at Figure 7,
and the hearth B having a tuyere box f and tuyeres 8, also shewn in
plan at Figure 8; these tuyere boxes are both supplied with air from a
blast engine in the usual manner by means of the pipes 9 and h which
communicate with the hollow axis of the vessel where stuffing boxes of
the ordinary kind may be employed, and thus admit of the rotation of the
vessel on its axis without disconnecting the said pipes. The means of giving
axial motion to the vessel is not shewn, as the same may be readily accom-
plished by hydraulic apparatus as already practised. The pipe g which
conveys air into the tuyere box e serves also to convey steam thereto
when required by means of two cocks, one of which communicates with
a steam boiler or steam superheater and the other with the reservoir of
compressed air, so that during the process either air or steam or air and
steam mixed may be passed together at will through the tuyeres. The
converting vessel having been heated by blowing up a coke fire as usual
therein, and the residue of the fuel turned out, the vessel is to be turned
into a position suitable for receiving the fluid iron. Some "mill scales,"
"hammer slag," "red ore," or any other matters such as it has hitherto
been found desirable to use in puddling iron may be put into the
hearth A, and then a charge of molten iron of a cheap or inferior quality
may be run in. The position of the vessel at this time is shewn in

page_text: Figure 3, where it will be observed that the metal i is kept below the
level of the tuyeres prior to the commencement of the process. A blast
of air or steam is then turned on through the tuyeres into the small
hearth A, and the vessel turned up so as to cause the molten metal
to run into the hearth A, as shewn in Figure 2, and be operated upon
by the blast. It must be understood that the tuyeres in the small
hearth A are of a smaller size and are less in number than is usually
employed in the Bessemer process. As soon as the iron is somewhat
raised in temperature, the workman by means of a suitable valve or
cocks will turn on steam with the air, or he will use steam alone. The
result of the partial decarbonization of the metal by the slow action
of a restricted supply of air and the cooling effect of steam operating
with the mill scales and other matters will tend to convert the metal
into a pasty or granular mass mechanically mixed with fluid cinder.
The constant and somewhat violent heaving up of the mass by the jets
of air or steam tends to divide the metal and disseminate it in a more
or less granular form throughout the fluid cinder. Additions of mill
scales, iron ore, or oxide of manganese, or other substances used to form
puddling cinder may be added as thought desirable, and if the mass
becomes too stiff an iron bar may be introduced at the openings n before
named and the metal thereby raised and divided; meantime the use
of steam may be discontinued and replaced by a blast of air which will
rapidly restore the temperature necessary to carry on the process. The
management of the heat and the employment of air or steam from time
to time will thus be left to the judgment and experience of the operator,
who will judge of the state of the metal partly by the heavy sound of
the escaping blast as it heaves up the metal, and also by the condition
of the flame and sparks emitted from the mouth of the vessel. As soon
as the workman judges that the process has been carried far enough
he will turn down the vessel and run therein a charge of molten iron
from a neighbouring furnace, the iron so added may be a good grey
hoematite or some other good quality of iron, preferably containing a
little manganese and sufficient carbon; he will then turn up the vessel
so far that both portions of the metal will run into the second or larger
hearth B, as shewn at Figure 1, where the tuyeres and tuyere holes are
larger and more numerous than in the first hearth, so that a powerful
blast of air may be driven through the metal and increase its temperature
and completely melt the first charge and unite therewith; the metal
may then be run from the vessel into a ladle in the state of steel, but

page_text: I prefer to entirely decarbonize the double charge of metal before running
it from the vessel, and add thereto a known quantity of manganesian
pig iron in a fluid state as commonly practised in making Bessemer
steel.
Although I have herein described how the first portion of the charge
consisting of an inferior iron, may be purified by a process similar in
its effects to the process of puddling, I desire it to be understood
that the first portion of the charge in the hearth A may be in part
decarbonized and refined by forcing into the fluid metal jets or currents
of fluid nitrates of soda or nitrates of potash, or other fluid matters
containing or capable of evolving oxygen when brought in contact
with molten iron, by means of tuyeres or nozzles in the manner fully
described in the Specification of a former Patent granted to me, No. 965,
and bearing even date with the Patent of which this is the Specification,
my claim to the use of such modes of decarburizing or purifying crude
iron by means of nitrates or chlorates under these Letters Patent being
restricted to their employment on a portion only of the metal to be
converted at one time in the vessel as described.
In order to prevent the rapid wear of furnaces employed in fusing
malleable iron or steel on the hearth of such furnaces I construct the
roof and parts most exposed to heat with hollow bricks or with passages
between them, through which I pass a current of air to keep down their
temperature; and I also utilize the heat so abstracted by using the heated
air to sustain combustion in such furnaces.
In carrying into practical operation this part of my Invention I prefer
to mould the bricks of the form shewn in Figure 9 (although many
other forms may be used), the sides of such bricks being tapered as
required to form an arch; their arrangement in the roof of a furnace is
shewn in Figure 10, where they form several passages m, which may
extend from end to end of the furnace, a current of air being either
forced through them or caused to flow through by means of chimney
draught, the cooling effect of which will prevent the bricks from being
so rapidly destroyed as would be the case if solid bricks were employed.
Secondly. My Invention consists in applying the combined action of
furnace heat with the heat developed by jets or currents of air forced
into fluid iron when applied to mixtures of solidified iron or steel with
molten carburets of iron for the purpose of fusing such solid portion

page_text: and for decarbonizing the same, so as to produce from such mixed
materials fluid malleable iron or steel.
Crude or pig iron of an inferior quality may be more or less purified
by puddling, and either in the state of malleable iron or puddled steel,
and in a loose granular condition, or as puddle balls, may be removed to
another suitable furnace; or it may be treated in the furnace in which
the puddling process has been carried on. Some molten iron in either
case is then added, and a blast of air is driven up through the metal,
raising its temperature, and causing by its joint action with the furnace
heat the solid portions of the charge to fuse and blend with the rest
and pass into the condition of molten malleable iron or steel. When
tapped from the furnace it may be mixed with spiegeleisen or ferro-
manganese, and then formed into ingots or other castings.
I also employ the same combined action of jets of air and furnace
heat for the fusion and conversion of wrought scrap iron of any kind
and other masses of wrought iron, such as old iron, railway bars, and
also any steel scraps, skulls, spillings, and crop ends of steel rails or
forgings.
I prefer to employ for the purposes of this second part of my
Invention a reverberatory gas regenerative furnace or other gas furnace
in which heated air and gas are used.
The jets or currents of air may be forced into the molten metal
through moveable pipes or tuyeres, but I prefer to employ fixed tuyeres
made of fire-clay, and to stop up or cover over the ends thereof with
fire-clay, loam, or ganister previous to turning on the air, the stopping
being removed with an iron rod or by the pressure of the air, as may
be found most convenient.
This mode of treatment is also applicable to iron which has been
more or less purified or rendered into steel or malleable iron by the
action thereon of nitrate of soda or nitrate of potash, or other substances
which yield oxygen on coming in contact with molten iron. Should
such metal have become solidified, wholly or partially, I render it again
fluid by mixing with it molten pig iron in a furnace heated by fuel;
and I also force jets of air into the fluid portion of the mixture.
Or
the process may be conducted in the vessel in which the nitrates or
similar substances were applied, the fire heat and air jets being used
in this vessel.

page_text: Having described the several parts of my Invention, and the
manner in which the same may be carried into practical operation,
I desire it to be understood that I do not confine myself to the
precise details herein given, provided the essential parts of my said
improvements be retained; but what I claim in the manufacture of
malleable iron and steel and in apparatus used in such manufacture
is as follows:-
Firstly. I claim the treatment and purification of molten pig or
other carburet of iron in a converting vessel by means of currents of
air and steam used separately or combined, and applied in such manner
that the metal shall thereby be rendered semi-fluid, pasty, or granular,
and become mechanically mixed with the slags or "cinder" formed
in the process, and subsequently the admixture therewith in the same
vessel of a further portion of molten pig or other carburet of iron,
and the effecting the complete fusion of such metallic mixture into
fluid malleable iron or steel by forcing air in sufficient quantities
upward through it.
Secondly. I claim the employment of nitrates of soda or nitrates
of potash to act on and purify molten pig or other carburet of iron
in a converting vessel, and the subsequent admixture in the same
vessel of the iron so treated with another portion of pig or other
carburet of iron, and the conversion of such mixture into fluid steel
or malleable iron by means of currents of air forced upwards through
the metal.
Thirdly. I claim the construction and employment in the manufacture
of malleable iron and steel of converting vessels having two hearths
or cavities and separate tuyere boxes, as herein described.
Fourthly. I claim in the construction of furnaces suitable for fusing
malleable iron or steel on the hearths thereof the use of hollow fire-
bricks arranged to form flues or passages through which currents of
air may be caused to pass, as described.
Fifthly. I claim the fusion of malleable iron or steel or other
partially decarbonised puddled or purified iron on the sole or hearth
of a gas or other reverberatory furnace by adding to the materials to
be fused a portion of pig iron or carburet of iron, and forcing air into
it so as to cause heat to be generated, which heat acting in conjunction
with the heat of the furnace and by joint action therewith fuses the

page_text: solid portions of the metal, and blending the mixture converts the
whole into fluid malleable iron or steel.
In witness whereof, I, the said Henry Bessemer, have hereunto
set my hand and seal, this Twenty-first day of September, in
the year of our Lord One thousand eight hundred and sixty-
eight.