IMPROVE- MENTS IN THE CONVERSION OF FLUID CRUDE IRON AND MOLTEN PIG OR OTHER CARBURETS OF IRON INTO FLUID HOMOGENEOUS MALLEABLE IRON AND STEEL, WHETHER SUCH PIG OR OTHER CRUDE IRON IS USED ALONE OR IS MIXED WITH A PORTION OF MALLEABLE OR MORE OR LESS DECARBURISED IRON IN A SOLID OB FLUID STATE
Year: 1869

page_text: LETTERS PATENT to Henry Bessemer, of Queen Street Place, Cannon
Strect, in the City of London, for the Invention of "IMPROVE-
MENTS IN THE CONVERSION OF FLUID CRUDE IRON AND MOLTEN PIG OR OTHER
CARBURETS OF IRON INTO FLUID HOMOGENEOUS MALLEABLE IRON AND STEEL,
WHETHER SUCH PIG OR OTHER CRUDE IRON IS USED ALONE OR IS MIXED WITH
A PORTION OF MALLEABLE OR MORE OR LESS DECARBURISED IRON IN A SOLID OB
FLUID STATE."
Sealed the 6th July 1869, and dated the 10th May 1869.
PROVISIONAL SPECIFICATION left by the said Henry Bessemer at
the Office of the Commissioners of Patents, with his Petition, on
the 10th May 1869.
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 CONVERSION OF FLUID CRUDE IRON AND MOLTEN PIG OR
OTHER CARBURETS OF IRON INTO FLUID HOMOGENEOUS MALLEABLE IRON AND. STEEL,
WHETHER SUCH PIG OR OTHER CRUDE IRON IS USED ALONE OR IS MIXED WITH A

page_text: PORTION OF MALLEABLE OR MORE OR LESS DECARBURISED IRON IN A SOLID OR
FLUID STATE," to be as follows:-
The decarburation or partial decarburation of molten crude iron or
remelted pig or other carburet of iron may be effected by passing atmo-
spheric air upward through the fluid metal in suitable vessels in the
manner now generally known as the "Bessemer process." It has
however been found that certain of the purer qualities of Swedish pig
iron made with charcoal, and also some of the less grey and the white
hemitite pig iron of this country, do not produce sufficient heat in the
converting vessel under ordinary circumstances to allow all the steel
made therefrom to retain complete fluidity until it is poured into moulds,
and hence sometimes it happens that large "skulls" or shells of solidified
steel are left in the casting ladle. This evil is increased when malleable
scrap iron or steel is added to the charge of metal in the converter.
Now one of the chief objects sought to be obtained by my present
Invention is to rise the temperature of the metal during the process of
conversion so high that no skull or solidified metal shall be left in the
casting ladle when employing carburets of iron not rich in graphitic or
other carbon, and thus enable the manufacturer to use many qualtities of
iron that do not produce a maximum of heat under the ordinary con-
verting process, and also enable him to put into the converting vessel a
portion of steel scrap, or scrap iron, or other kinds of decarburized or
malleable iron in a solid state, and which by means of the extremely
high temperature imparted to the metal become fused, and form part of
the charge of molten malleable iron or steel obtained. For this purpose
I make the converting vessel of great stength, securely rivetting and
caulking all the laps and joints so as to render it air-tight as near as may
be. I, by preference, form the mouth of the vessel circular instead of
oval, and of a smaller size than usual, lining the mouth with a single
ring of well burned fire-clay or composition of clay and plumbago; and
I form the metal part of the mouth of the converter with a moveable
dovetailed flanged ring, so that the firc-clay mouth of the vessel may be
readily taken out and renewed by unbolting or uncottering the iron ring
which retains it in place. The aperture in the moveable mouth of the
vessel thus formed may be made small enough to retain the gaseous
products resulting from the combustion of the carbon or other matters
contained in the pig iron under a pressure much above that of the
surrounding atmosphere, so that the combustion going on in the con-

page_text: verting vessel may be under "high pressure," as described in reference
to melting furnaces in the Specification of a Patent granted to me, and
bearing date the 10th day of November 1868, and numbered 3419, or the
opening in the mouth of the converting vessel may be made much too
large to retain the gaseous matters in the converter at the high pressure
desired, such larger sized mouth being provided with a conical stopper
inserted in the opening, and so arranged as to be advanced or further
withdrawn by being itself moveable or by the motion of the vessel on
its axis, the vessel being made to advance towards or recede from a
fixed conical stopper, or in lieu thereof a flat or other shaped surface may
be employed, the object in either case being to enlarge or contract the
opening for the escape of flame as found desirable at different stages of
the process.
The pressure of the confined gaseous products being
indicated by a mercurial column will allow the workmen to employ from
time to time such an amount of internal pressure in the vessel as the
known qualities of the material he employs may render necessary. A
pressure of 10lbs. per square inch in the converter in excess of the
external atmospheric pressure will add very much to the temperature of
the metal, and will in most cases be sufficient, the pressure of the blast
being in all cases sufficient to overcome the pressure of the column of
fluid iron opposed to it as well as the internal pressure of the gaseous
products confined within the vessel. When crude molten iron or
remelted pig or refined iron are decarburized or partially decarburized or
converted into malleable iron or steel by the action of nitrate of soda
or potash, or by other oxydizing salts, as set forth in a Patent granted to
mc, and bearing date the 21st day of March 1868, and numbered 965, or
when such decarburation or conversion is effected by any other modes or
processes in which the decomposition of nitrate of soda or potash or
other oxygen yielding salts takes place in or among the fluid metal, a
large amount of heat is absorbed and rendered latent, thus tending to
solidify the metal, and rendering it unfit for forming into ingots without
being remelted.
Now the object of another part of my said Invention is to raise the tem-
perature of metal so treated or converted to such a degree as to allow it to
be cast into ingots or other cast articles or masses prior to its solidification.
For this purpose I construct the vessels in which the process is to be
carried on of great strength, preferring to use stout iron or steel plates well
rivetted and caulked, and if needful further strengthened by stout hoops.

page_text: I make the mouth of the vessel very small, preferring for that purpose
to employ a well burned fire-brick ring, into which a long taper cone of the
same material is placed. The cone is fastened to a long rod working in
suitable guides so as to keep it central with the mouth of the vessel. The
space between the exterior of this cone and the interior of the fire-clay
ring determines the area of outlet for the gaseous products given off
during the time that the decomposition of the nitrate or other materials
is going on. A weight or spring lever acting on the rod to which the
fire-clay cone is attached may be made to regulate the amount of
pressure required to lift the cone and permit the escape of the gaseous
matters. Any other suitable valve may be employed, or a mere restricted
outlet may be used, the object in either case being to prevent the free
escape of the gaseous matters resulting from the combustion of the carbon
contained in the crude iron, and to retain the gaseous products therein
under a pressure of several atmospheres if needful, and thus cause the
heat developed by the combustion of the carbon contained in the crude
iron to become highly concentrated, and the metal thereby raised in
temperature.
An artificial atmosphere of air or steam under greate pressure may be
employed if desired at the commencement of the process, and the valve
or restricted outlet may be enclosed within a tube or shaft, whereby the
gaseous matters may be conveyed away. The opening by which the
metal is admitted must also be securely closed to prevent any escape of
the gases from the metal.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry Bessemer in the Great Seal Patent Office
on the 10th November 1869.
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 Tenth day of May, in the year of our
Lord One thousand eight hundred and sixty-nine, in the thirty-second
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,

page_text: the said Henry Bessemer, my executors, administrators, and assigns, or
such others as I, the said Henry Bessemer, my executors, adminis-
trators, 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 "IкPROVEMENTS IN THE CONVERSION
OF FLUID CRUDE IRON AND MOLTEN PIG OR OTHER CARBURETS OF IRON INTO
FLUID HOMOGENEOUS MALLEABLE IRON AND STEEL, WHETHER SUCH PIG OR OTHER
CRUDE IRON IS USED ALONE OR IS MIXED WITH A PORTION OF MALLEABLE OR MORE
OR LESS DECARBURIZED IRON IN A SOLID OR FLUID STATE," 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 calender months next and immediately 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:-
The decarburation or partial decarburation of molten crude iron or
remelted pig or other carburet of iron may be effected by passing
atmospheric air upward through the fluid metal in suitable vessels in
the manner now generally known as the Bessemer process. It has
however been found that certain of the purer qualities of Swedish pig
iron made with charcoal, and also some of the less grey and the white
hematite pig irons of this country, do not produce sufficient heat in the
converting vessel under ordinary circumstances to allow all the steel
made therefrom to retain complete fluidity until it is poured into moulds,
and hence sometimes it happens that large "skulls" or shells of
solidified steel are left in the casting ladle. This evil is increased when
malleable scrap iron or steel in a solid state is added to the charge of
metal in the converter.
Now one of the chief objects sought to be obtained by my present
Invention is to rise the temperature of the metal during the process of
conversion so high that no skull, or solidfied metal shall be left in the

page_text: casting ladle when employing carburets of iron not rich in graphitic or
other carbon, and thus enable the manufacturer to use many qualities of
iron that do not produce a maximum of heat under the ordinary con-
verting process, and also enable him to put into the converting vessel a
portion of steel scrap or scrap iron or other kinds of decarburized or
malleable iron in a solid state, and which by means of the extremely
high temperature imparted to the metal become fused and form part of
the charge of molten malleable iron or steel obtained. For this purpose
I make the converting vessel of great strength, securely rivetting and
caulking all the laps and joints so as to render it air-tight as near as
may be. I, by preference, form the mouth of the vessel circular instead
of oval, and of a smaller size than usual, lining the mouth with a single
ring of well-burnt fire-clay or composition of clay and plumbago, and I
form the metal part of the mouth of the converter with a moveable
dovetailed flanged ring, so that the fire-clay mouth of the vessel may be
readily taken out and renewed by unbolting or uncottering the iron ring
which retains it in place.
And in order that this mode of constructing the mouth of the con-
verting vessel may be fully understood, I have represented the same in
vertical section at Figure 1 on the Sheet of Drawings hereunto annexed,
where a represents the upper part of a Bessemer converting vessel; a*, the
lining of ganister; and b, the strong rivetted iron shell or vessel on the
inside of the mouth of which the iron hoop c is rivetted; d is a flanged
iron ring bevilled on the inside, and secured by screwed studs or cotter
bolts to the hoop c. A moulded ring e of fire-brick or other suitablo
refractory material forms the escape opening or mouth of the vessel; it is
retained in place by means of the flanged ring d, and when it is worn
out or damaged the ring e may be renewed by unfastening the ring d, a
mixture of fire-clay and ganister being first smeared over those parts of
the ring e which come in contact with the lining a* and with the bevilled
interior of the ring d for the purpose of making the joint air-tight. The
aperture in the moveable mouth of the vessel thus formed may in some
cases be made small enough to retain the gaseous products resulting
from the combustion of the carbon or other matter contained in the pig
iron under a pressure much above that of the surrounding atmosphere,
so that the combustion going on in the converting vessel may be under
"high pressure," as described in reference to melting furnaces in the
Specification of a Patent granted to me, and bearing date the 10th day of

page_text: November 1868, and numbered 3419. The mode of forming this con-
traction of the mouth of the vessel for the purpose of retaining the
gaseous products under considerable pressure therein is shown in vertical
section at Figure 1, and is so much reduced in area as to cause the flame
and gaseous products evolved during the process to be pent up until a
considerable amount of pressure is produced in order that the gascous
products resulting from the combustion of carbon and other matters in
or among the fluid metal may be prevented from expanding freely, and
by reason of the combustion so taking place under a pressure much
greater than that of the external atmosphere a more intense heat will be
produced and imparted to the metal. The amount of pressure thus
obtained should vary with the heat producing properties of the carburet
of iron operated upon and the quantity of scrap or other unfused metal
forming part of the charge, so that no precise rule can be laid down as
to the pressure to be employed, but as a guide to the workman I desire
to state that for the conversion of the purer kinds of Swedish charcoal
pig iron and for mottled or white hematite pig iron mixed with grey a
back pressure in the, vessel from 8 to 15 lbs. on the square inch will give
good results, and in but few cases will a pressure of 20 lbs. per squaro
inch be necessary, while a pressure as low as 3 or 4 lbs. will be
but of little practical advantage, and below 2 lbs. per square inch I lay
no claim to as a useful effect. It will be understood that the pressure of
the blast of air forced into the converting vessel must be increased in
proportion to the back pressure caused by the penning up of the gases
within the vessel. I would also remark that the mode of obtaining the
required back pressure by simply diminishing the outlet does not offer
all the desired facility of regulating the pressure from time to time
during the process, while at the same time the accumulation of slags in
the aperture may in some cases reduce the area of outlet so much as to
retard the inflow of air through the tuyeres. For these several reasons the
opening in the mouth of the converting vessel may be made much too
large if left open to retain the gaseous matters in the converter at the
high pressure desired, such larger sized mouth being provided with a
conical stopper inserted in the opening, and so arranged as to be advanced
or further withdrawn by being itself moveable, or by the motion of the
vessel on its axis, the vessel being made to advance towards or recede from
a fixed conical stopper. I however prefer to use à moveable conical stopper
attached to the end of an iron rod, as shewn in Figure 2, which represents
the upper part of a Bessemer converting vessel with a contracted mouth.

page_text: piece, similar (but larger in diameter) to that represented in Figure 1,
the several parts of which are indicated by the same letters of reference.
The conical piece of fire-brick f is circular in form, and spreads outward
in a curved line at f* for the purpose of deflecting the flame and
preventing its too powerful action on the iron rod 9 which supports the
cone f. The rod g protrudes through the back wall of the converting
house, or may be supported on a bracket or piece of iron framing in
connection with the standards which support the vessel, and by means of
a screw or lever the cone f may be made to advance further into or
recede from the mouth of the vessel, thus increasing or diminishing the
area of the annular opening.at e*, and thus regulate the pressure of the
confined gases in the vessel. In some cases it may be found desirable to
render the stopper f self-acting by applying a spring or weighted lever
to press it forward against the pressure of the escaping gases, so that
either by reason of its enlargement by the accretion of slags on its
surface or by being partially burned away it will occupy such a position
in the mouth of the vessel throughout the process as will give a
sufficiently equal amount of back pressure, and prevent that pressure
from exceeding what is necessary by any partial clogging up of the
escape opening, or in lieu of employing a conical stopper a flat or other
shaped surface may be employed, the object in either case being to
enlarge or contract the opening for the escape of flame as found desirable
at different stages of the process; the pressure of the confined gaseous
products being indicated by a mercurial column so arranged that the
mercury is prevented from coming in contact with the heated products
of combustion by means of a current of air, as described in a Patent
bearing even date herewith, and numbered 1431; this guage will allow
the workmen to employ from time to time such an amount of internal
pressure in the vessel as the known qualties of the material he employs
may render necessary. When crude molten iron or remelted pig or
refined iron is decarburized or partially decarburized or converted into
refined iron or into malleable iron or steel by the action of nitrate of
soda or potash, or by other oxidizing salts, as set forth in a Patent
granted to me, and bearing date the 21st day of March 1868, and
numbered 965, or when such decarburation or conversion is effected by
any other modes or processes in which the decomposition of nitrate of
soda or potash, or other oxygen yielding salts alone or mixed with
metallic oxides takes place in, among, or below the fluid metal in a
converting vessel or chamber, a large amount of heat is absorbed and

page_text: rendered latent, thus tending to solidify the metal and rendering it unfit
for forming into ingots or castings without being remelted.
Now the object of this part of my said Invention is to raise the
temperature of metal (while so treated or converted) to such a degree as
to allow it to be cast into ingots or other cast articles or masses prior
to its solidification. For this purpose I construct the vessels in which
the process is to be carried on of great strength, preferring to use stout
iron or steel plates well rivetted and caulked, and if needful further
strengthened by stout hoops. I make the mouth of the vessel very
small, preferring for that purpose to employ a well-burned fire-brick ring
into which a long taper cone of the same material is placed. The cone
is fastened to a long rod working in suitable guides, so as to keep it
central with the mouth of the vessel. The space between the exterior
of this cone and the interior of the fire-clay ring determines the area of
outlet for the gaseous products given off during the time that the
decomposition of the nitrate or other oxygen yielding materials is going
on. A weight or spring lever acting on the rod to which the fire-clay
cono is attached may be made to regulate the amount of pressure
required to lift the cone and permit the escape of the gaseous matters.
Any other suitable valve may be employed, or a mere restricted outlet
may be used, the object in either case being to prevent the free escape of
the gaseous matters resulting from the combustion of the carbon con-
tained in the crude iron, and to retain such gaseous products in the
converting chamber or vessel under a pressure of several atmospheres if
needful, and thus cause the heat developed by the combustion of the
carbon contained in the crude iron to become highly concentrated, and
the metal thereby raised in temperature.
An artificial atmosphere of air or steam under great pressure may be
employed if desired at the commencement of the process, and the valve
or restricted outlet may be enclosed within a tube or shaft, whereby
the gaseous matters may be conveyed away. The opening by which the
metal is admitted must also be securely closed to prevent any escape of
the gases from the vessel.
The manner in which this part of my said Invention is carried into
practical operation is represented on the Sheet of Drawings hereunto
annexed, where Figure 3 represents a vertical section of the upper
portion of a converting vessel or chamber in which molten pig or other
carburet of iron is to be treated either by the injection of the fluid nitrate

page_text: into the molten metal, as described in a Patent granted to me on the
21st day of March 1868, for improvements in the manufacture of refined
iron and of malleable iron and steel, and numbered 965, or in which
vessel the nitrates or other oxygen yielding salts or substances are so
brought in contact with the hot metal as to be decomposed thereby.
The outer shell h of the vessel or chamber is made of thick plates of iron
or steel securely rivetted and caulked at all joints, and capable of with-
standing safely a pressure of from 5 to 10 or more atmospheres. For the
convenience of lining the vessel the upper part may be removed by
unbolting the stout flanges h¹. One or more hoops h² are rivetted to the
exterior of the vessel to strengthen it. A lining of fire-brick, ganister,
or other refractory material i is used to defend the outer shell from the
high temperature generated within, and previous to its use for conversion
I prefer to make a fire in the interior so as to highly heat the lining
and lessen its power of absorbing heat from the metal. On the upper
part of the dome an iron ring m is rivetted, to which a flanged ring n is
fitted. The inside of this ring is conical, and is made to embrace the
conical fire-clay ring p through which the gaseous matters evolved
during the process are allowed to escape. A cone of fire-clay or of
iron is attached to the guide rod r for the purpose of closing or
diminishing the area of the outlet opening in the fire-clay ring p. On
the upper end of the rod are placed weights s to regulate the pressure.
The rod is guided vertically upward and downward by passing through
the tubular guides and stuffing box formed at t, t, on the curved exit
passage, which leads to a chimney and conveys away the gaseous
products escaping from the converting chamber. On one side of the
vessel or chamber is a projection v, on the upper part of which a ring of
fire-brick wo is retained in place by a conical flanged iron ring x. The
opening in the ring to serves for the admission of the molten metal to
the vessel, after which the cone y smeared with fire-clay is lowered down
into the opening of the moulded fire-brick w, and by means of the
weight is retained in place and prevents the escape of gaseous matters
during the converting process. The cone y and its rod and weight = are
suspended by a chain in the position shewn during the period of running
in the metal. When the metal so run in comes in contact with the
nitrates or other oxygen yielding materials large volumes of gaseous
matters are evolved, as is well known and understood, which instead of
escaping freely from the vessel as heretofore practiced will rapidly
accumulate in the vessel until the pressure within it is sufficient to raise

page_text: the cone g, and escape by the small annular opening thus made, the
pressure being regulated by tho weight 8, and hence the combustion of
the carbon contained in the molten iron by reason of its union. with.
oxygen derived from the decomposition of the nitrates or other oxygen
yielding materials will be effected under considerable pressure. The
gaseous products instead of expanding freely as under the ordinary
conditions of combustion will be in a highly condensed state, by which
means their temperature will be considerably raised, and additional heat
so generated will be imparted to the metal and retain its fluidity.
Having thus described my Invention, and the manner in which it
may be carried into practical operation, I desire it to be understood that
I lay no claim under those in part recited Letters Patent to the con-
version of pig or other carburets of iron into malleable iron or steel by
the passage of air through the molten metal, nor by means of the action
of nitrates or other oxygen yielding substances thereon, so long as the
gaseous products evolved in either of these processes are allowed to
escape freely from the vessels or chambers in which such converting
processes are carried on; but what I do claim is,-
Firstly. I claim the constructing the Bessemer converting vessel in
such manner that the metal contained therein may have its temperature
increased by being exposed to a considerable back pressure of gases
during the converting process.
Secondly. I claim the converson of molten pig or other carburet of
iron into malleable iron or steel by passing atmospheric air through the
fluid metal contained in vessels in which the gaseous products of com-
bustion are retained above the surface of the metal at a considerablo
pressure in excess of the pressure of the external atmosphere.
Thirdly. I claim the employment of moveable rings or mouth pieces
in vessels employed to convert molten pig or other carburet of iron into
malleable iron or steel by the passing of atmospheric air through the
molten metal.
Fourthly. I claim regulating the pressure of the gaseous products of
combustion within the Bessemer converting vessel in the manner herein
described.
Fifthly. I claim the treatment of or conversion into malleable iron or
steel of molten pig or other carburet of iron by means of nitrate of soda
or nitrate of potash, or by other oxygen yielding salts or substances,

page_text: when such treatment or conversion is carried on in vessels or chambers
in which the gaseous products resulting from such treatment or con-
version are retained under considerable pressure, as and for the purposes
herein described.
Sixthly. I claim the apparatus and methods herein described for
effecting and regulating the pressure of the gaseous products within the
vessels or chambers in which molten pig or other carburets of iron is
treated or converted into malleable iron or steel by the action of nitrate
of soda or nitrate of potash or other oxygen yielding salts or substances.
In witness whereof, I, the said Henry Bessemer, have hereunto
set my hand and seal, this Tenth day of November, in the year
of our Lord One thousand eight hundred and sixty-nine.