IMPROVEMENTS IN THE MANUFACTURE OF IRON AND STEEL
Year: 1856

page_text: LETTERS PATENT to Henry Bessemer, of Queen Street Place, New Cannon
Street, in the City of London, for the Invention of "IMPROVEMENTS IN
THE MANUFACTURE OF IRON AND STEEL."
PROVISIONAL SPECIFICATION left by the said Henry Bessemer at
the Office of the Commissioners of Patents, with his Petition, on the
4th January 1856.
I, HENRY BESSEMER, of Queen Street Place, New Cannon Street, in the
City of London, do hereby declare the nature of the Invention for "IMPROVE-
MENTS IN THE MANUFACTURE OF IRON AND STEEL" to be as follows:-
In the process of refining iron as generally practised in Great Britain, a
'finery or running-out furnace" is used, in which the pig iron is placed upon
a heap of coke which occupies the hearth of the furnace; more coke is then
laid upon the iron, and a powerful blast is kept up until the metal is melted,
and has run down into the hearth, and displaced the coke which at the com-
mencement of the process occupied that part of the furnace; the melted iron
will then present only its upper surface to the action of the fire, while the
bottom and sides of the hearth will absorb a portion of the heat from the
metal; at the same time the decarbonization of the iron which is going on. will
render it less easily fusible; hence it follows, that the complete decarbonization
of the metal cannot be effected in such furnaces, in consequence of the
insufficient degree of heat applied to the surface of the metal, which would in

page_text: '
consequence become solidified. It has therefore been the general practice
only to partially refine the metal in such furnaces, and to complete its refine-
ment by the process of puddling in a furnace peculiarly adapted for such
purpose, and in which process the iron passes from the fluid to the pasty or
solid state.
Now, the object of my present Invention is the more perfect and complete
refinement of the iron, whereby it gradually loses tho properties common to
pig or crudo iron, and acquires the properties of cast steel, or of pure or
decarbonized iron, while it still preserves such a state of fluidity as will admit
of its being cast into ingots or other desired forms or articles, by the process of
founding. For which purpose I expose the iron in a more divided or extended
form to the intense heat of the furnace or furnaces herein-after described, and
to the oxydizing action of a blast of air, by keeping such fluid metal in
motion, and continually bringing fresh portions of it in contact with oxygen,
and' with the intensely ignited fuel, or with the highly heated interior surface of
the furnace, the metal being thus kept in a fluid state until the desired amount
of decarbonization or refinement is arrived at. The iron to be used for the
purposes of my present Invention may be conveyed by a gutter in a fluid state
direct from the smelting furnaco where it has been obtained from the ore, and
be allowed to flow into the improved furnace or furnaces herein-after described,
or it may be obtained from any convenient form of remelting furnace, or the
iron may undergo 1. previous partial refinement in the old or any other con
venient way; and which iron I proceed to complete the refinement of in any
one of the following modifications of apparatus:-
The first and most simple arrangement consists of a series of small cupola
or blast furnaces, so placed in reference to each other on a series of steps
that the fluid metal may flow from one to the other. An arch or slab of fire
clay in the upper part of each furnace will receive the stream of fluid iron
as it flows from the bottom of the upper furnace into the top of the furnace
immediately below it; the metal will by this means be scattered, and fall in a
shower through the highly heated fuel, and through the blast of air which
finds its way in an upward direction through it; the fluid iron will thus
pass in succession through several different furnaces, and collecting in the
bottom one, may be tapped from it as required.
A second modification of my improved apparatus consists of two cupola. or
blast furnaces, placed side by side and very close to each other; beneath each
furnace I place a strong iron tube or cylinder, into which 1 fit a plunger or
ram, similar to a hydraulic press; upon the head of each ram I construct the
furnace, so that by a suitable pump each of the furnaces may in succession be

page_text: raised above the level of the other; the upper one being then made to distri-
bute the fluid metal contained therein into the lower one, the metal falling
in a shower and passing down among the fuel, and in this divided state offer-
ing a considerable amount of surfaco to the decarbonizing action of the blast
of air passing upwards through the furnace, the alternate raising and lowering
of the two furnaces admitting of a continuation of the process for any required
length of time. The blast pipo attached to each furnace must be made to slide
vertically in and out of a fixed piece of pipe, so that the blast may be kept up
notwithstanding the movement of the furnaces; there must also be formed on
the said furnaces suitable spouts for the discharge of the metal, both for the
supply of each other, and for the final discharge of the metal into the mould
after its refinement is completed.
.
The third arrangement of apparatus which may be used for carrying into
effect my said Invention, consists in forming a furnace of a cylindrical or
spherical form, the outside shell being composed of boiler plate lined internally
with fire bricks coated with loam; the furnace is to be mounted on hollow
horizontal axes which are mounted in a suitable frame, so that rotary motion
may be communicated to the furnace. On the interior I form several shelves
or ribs, for the purpose of lifting up the fluid metal and letting it fall again
through the fuel, and so on continuously until the refinement of the iron is
effected. It will be observed that those parts of the furnace which at one part
of its revolution form the roof, and aro exposed to the intense heat of the
fuel, will at another part of its revolution form the bed on which the chief
portion of the metal rests; and hence, instead of their being a continual loss of
heat from the metal, from its absortion by the bed of the furnace, there will be
a constant accession of heat to the metal, by the highly heated interior surface
of the furnace descending below the fluid metal, and forming for the time the
bed on which the metal rests. In some cases the shelves may be dispensed with,
which will allow the metal quietly to slidee over the highly heated surface of the
interior of the furnace, the fuel floating on the surface of the metal. In either
case it will be understood that the axes of the furnace will be made hollow,
and of such a diameter as to admit the blast pipe at one end, while the opposito
one is made large enough to admit the fuel and metal, and at the same time
serve as a means for the products of combustion to escape. Although the hori-
zontal revolving furnace herein lastly described has the advantage of always
presenting newly heated surface for the metal to rest on, it nevertheless does
not present so large a surface of fluid iron to the action of the fire, and to the
decarbonizing action of the blast, as. may be obtained by causing the furnace
to revolve on a vertical axis in the manner herein-after described; and which
C

page_text: modification of furnace I prefer for the purposo of refining iron until so
much of its carbon has been driven off as to give to the said crude iron the
properties of, or to convert it into, steel, or puro or nearly pure refined iron.
And here I would observe, that for ordinary purposes coke may be used for
fuel for carrying into effect my said Invention, although I in all cases where
the quality of the metal is of great importance prefer to use charcoal, wood,
or prepared peat, as the effects of such last-named fuels are less injurious to
the metal than coko made from mineral coal.
. In constructing furnaces to revolve on a vertical axis, the cylindrical form
is most suitable; the outside shell (being made of strong boiler plato soundly
rivited) is to be lined with fire brick and coated with loam, the upper part
being closed partly over, leaving a central hole at the top, of about one-third
the diameter of the furnace; the bottom of the furnace is formed of cast iron,
strongly ribbed and keyed on to a spindle; the foot of this spindle rests in a
foot-step sunk several feet below the ground level, the upper part of tho
spindle working in a bearing formed in an iron framo secured to heavy
masonry; this spindle has keyed upon it'a wheel, by which a rapid rotary
motion is given to it. A fire having been made in the furnace, and a
powerful blast applied to it, either through the centre of the furnace at bottom,
or-by nozzles at the sides, which communicate with a hollow space around the
axis; when the interior of the furnace is brought up to an intenso heat, the
fluid iron may be run into it, 'and a rapid motion communicated to the furnace,
whereby the fluid metal will rise up the sides of it as far as where the top
closes over, and be there suspended by centrifugal force, the metal being
distributed in a cylindrical layer of a few inches only in thickness; the fuel and
heated vapours will by the same agency be pressed continually in contact with
the fluid metal, and act powerfully thereon. By diminishing and increasing
_alternately_thic speed of the furnace, the metal will rise up or sink lower
down in the furnace, and thus afford constantly-fresh surfaces to the action of
the fire and oxygen present in the furnace, which, by combining with the
carbon contained in the iron, will refine and purify it to the required extent.
In some cases, however, I find it preferable to introduce a fire-clay pipe.
into the fluid metal in the bottom of the furnace, and by means of it force a
current of hot air into and among the Buid metal; when the metal is somewhat
cooled, the pipe may be withdrawn, and the motion of the furnace continued
until it has been again heated up, when the process of blowing air or steam
through the fluid metal may be repeated; and here I would remark that hot
or cold air may be used, but I prefer hot blast, and that it should be heated
to the highest practicable limit. As soon as the complete refinement of the

page_text: metal is effected, the motion of the furnace may be discontinued, and the
fluid steel or iron be tapped out of the side of the furnace as usually practised
in cupola furnaces used for melting iron, the metal so run out being received;
into suitable ingot moulds, whereby blocks of metal will be formed, suitable for:
hammering or rolling into bars, plates, rails, or rods, and which may be either
hard steel, soft steel, hard iron, or soft iron, according to the extent of the
refining process. And here I would observe, that when I desire to make steel
of a superior quality, I carry out the refinement of crude iron as far as possible,.
and produce thereby soft iron, which I cast while in a fluid state into ingots,
which.I afterwards roll into bars or rods of the desired form and size; the
iron bars thus formed, I cement with charcoal in the manner already practised.
in making blister steel; but the cemented bars made from cast ingots of iron
will not form blisters, in consequence of their freedom from iron scales.:
When the process of cementation has been carried to the desired extent, the
bars are removed from the cementing chest, and again rolled or tilted, as
already practised in the manufacture of steel.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Henry Bessemer in the Great Seal Patent Office on the
4th July 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
BESSEMER, of Queen Street Place, New Cannon Street, in the City of London,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourth day of January, in the year of our Lord One
thousand eight hundred and fifty-six, in the nineteenth 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 Bessemer, 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 IRON AND STEEL," upon the condition (amongst others) that I,
the said Henry Bessemer, any executors or administrators, by an instrument
in writing under my, or their, or one of their hands and seals, should par-

page_text: ticularly 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 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:-
In the process of refining iron as generally practised in Great Britain, a
"finery or running-out furnace" is used, in which the pig iron is placed upon
a heap of coke which occupies the hearth of the furnaco; more coke is then
laid upon the iron, and a powerful blast is kept up until the metal is melted
and has run down into the hearth, and displaced the coke which at the
commencement of the process occupied that part of the furnace; the melted
iron will then present only its upper surface to the action of the fire, while
the bottom and sides of the hearth will absorb a portion of the heat from the
metal; at the same time the decarbonization of the iron which is going on will
render it less easily fusible; henco it follows, that the complete decarboniza-
tion of the metal cannot be effected in such furnaces, in consequence of the
insufficient degree of heat applied to the surface of the metal, which would in
consequence become solidified. It has therefore been the general práctico
only to partially refine the metal in such furnaces, and to complete its refine-
ment by the process of puddling in a furnace peculiarly adapted for such
purpose, and in which process the iron passes from the fluid to the pasty or
solid state.
Now, the object of my present Invention is the more perfect and completo
refinement of the iron, whereby it gradually loses the properties common to pig or
crude iron, and-acquires the properties of cast steel, or of pure or decarbonized
iron, while it still preserves such a state of fluidity as will admit of its-being
cast into ingots or other desired forms or articles, by the process of founding.
For which purpose I expose the iron in a more divided or extended form to
the intense heat of the furnace or furnaces herein-after described, and to the
oxydising action of a blast of air, by keeping such fluid metal in motion,
and continually bringing fresh portions of it in contact with oxygen, and
with the intensely ignited fuel, or with the highly heated interior surface of
the furnace, the metal being thus kept in a fluid state until the desired amount
of decarbonization or refinement is arrived at.
The iron to be used for the purposes of my present Invention may be
conveyed by a gutter in a fluid state direct from the smelting furnace, where

page_text: it has been obtained from the ore, and be allowed to flow into the improved
furnace or furnaces; herein-after described, or it may be obtained from any
convenient form of remelting furnace, or the iron may undergo a previous
partial refinement in the old or any other convenient way; and which iron
I proceed to complete the refinement of in any one of the following modifi
cations of apparatus.
The first and most simple. arrangement consists of a series of small cupola
or blast furnaces, so placed in reference to each other on a series of steps,
that the fluid metal may flow from one to the other. An arch or slab
of fire clay in the upper part of each furnace will receive the stream. of
fluid iron as it flows from the bottom of the upper furnace into the top
of the furnace immediately below it, or the metal may be allowed to flow,
on to the fuel; in either case the metal will by this means be scattered, and
fall in a shower through the highly heated fuel, and through the blast of air
which finds its way in an upward direction through it; the fluid iron will thus
pass in succession through several different furnaces, and collecting in tho
bottom one, may be tapped from it as required.". The cupola furnaces used in
carrying out this part of my present Invention may be constructed precisely
similar to those at present in general use by iron founders, and may bo
supplied with a blast of air also in a similar manner, the tap hole of each
furnace in the series being left open so as to allow the metal to flow out as
fast as it accumulates in the lower part of the furnace, or the tap holes may
be stopped with loam in the usual way, and the metal be retained therein,
until the whole or a greater part of it is accumulated previous to allowing it
to flow into the next furnace of the series, the lower one in all cases having
its tap hole stopped, so that all the metal may be there collected, and be
afterwards run into ingot or other moulds, as desired."
"A second modification of my improved apparatus consists of two cupola or
blast furnaces placed side by side and very close to each other; beneath each
furnace I place a strong iron tube or cylinder, into which I fit a plunger or
ram, similar to a hydraulic press; upon the head of each ram I construct the
furnace, so that by a suitable pump each of the furnaces may in succession
be raised above the level of the other; the upper one being then made to dis-
tribute the fluid metal contained therein into the lower one, the metal falling
in a shower and passing down among the fuel, and in this divided state offering
a considerable amount of surface to the decarbonizing action of the blast of
air passing upwards through the furnace, the alternate raising and lowering
of the two furnaces admitting of a continuation of the process for any required
length of time. The blast pipe attached to each furnace must be made to

page_text: slide vertically in and out of a fixed piece of pipe, so that the blast may be
kept up notwithstanding the movement of the furnaces; there must also be
formed on the said furnaces suitable spouts for the discharge of the metal, both
for the supply of each other and for the final discharge of the metal into the
mould after its refinement is completed."
In order that this modification of my Invention may be fully understood
I have hereunto annexed a Sheet of Drawings, marked A, on which I have
represented at Figure 4 a pair of cupola or blast furnaces, one of which is
shewn in elevation, and the other in vertical section.
a is a cupola or blast furnace of the usual construction; it is fixed on the
head of a hydraulic ram b; the ram is accurately fitted to the upper part of
the cylinder c, so as to keep it steady, and is kept water-tight by a leather ring
at d, as commonly used in hydraulic presses. The cylinder c has a large
flange at its upper end, which rests on the foundation plate e; at fis shewn
another cupola or blast furnace in section; it is in all respects similar to the
one already described; it is supported on a ram g, which works in a cylinder h.
Hot or cold blast is supplied to these furnaces from the main pipe i, having
elbows m, which turn upwards and are joined to the bed plate e; resting on
the bed plate are two cylinders r, of cast iron, the tops of them being fitted
with stuffing boxes, so as to enable the tuyero pipes s to slide in and out of
them freely, but without loss of air.
The action of the apparatus is as follows:-A fire being lighted in both
furnaces, the blast is to be applied until the fuel is well burned up, and
the interior of them brought up to a very high temperature; after which
a charge of fluid iron from the smelting furnace may be run into the
furnace a, or pig iron may be put in with the fuel, as is usually practised
in smelting iron for foundry purposes. In either case, the iron having
collected in the bottom of the furnace, a two-way cock (not shown in the
Drawings) is to be opened, so as to admit water from an elevated reser-
voir to flow into the cylinder c by the pipe t; the effect of which will be to
raise the ram 6 and furnace a into the position shewn in the Drawings. A
workman standing on a suitable platform (not shewn in the Drawings) will
open the tap hole of the furnace a, when the metal will flow out, as shewn, at u,
and falling on to the fuel in the furnace f, will be divided into numerous
globules, and descend among the fuel in a sort of shower, meeting in its
descent the blast of air which is always forcing its way upwards among the fuel
from the tuyere, and thus a partial decarbonization of the metal will be
effected. As soon as the whole charge has accumulated in the furnace f, the
two-way cock, before referred to, is to be reversed, whereby the water from

page_text: the elevated reservoir will enter the cylinder h by the pipe v, and raise up the
ram g and furnace f, while the water will leave the cylinder c, and allow the
ram band furnace a to be lowered down; the workman will then plug the tap
hole of the furnace a and open that of the furnace f, so that the metal may
fall as a shower among the incandescent fuel in the furnace a, and thus
acquire an additional temperature, accompanied with a further decarbonization
of the metal, and thus the alternate action of the two furnaces may be kept up
until the desired amount of decarbonization or refinement is obtained; after
which the fluid metal may be run from the tap hole into a ladle, and be then
poured into ingot or other moulds; or the fluid metal may be run into the
moulds direct from the furnace. The workman who conducts the operation
should make small sample ingots as the process proceeds, so as to enable him
to judge of the state of the metal, which may be made into hard or soft steel,
or into steely or soft malleable iron, according as the quantity of carbon
originally combined with the crude iron is reduced by the action of the blast
of air which is passing upwards through the furnace.
In either of the modifications of apparatus herein described, hot or cold air
may be employed, and it should always be used in excess of the quantity
required for the combustion of the fuel, in order that the gaseous matters in
the furnaces may contain onough oxygen to act upon the metal. Charcoal,
wood, or coko may be used separately or mixed as fuel, and the refinement
and purification of the metal may be assisted, if desired, by the use of salt,
oxide of manganese, iron scales, or other matters that have hitherto been
employed for such purposes in the process of puddling iron.
I have before remarked that a portion of the heat of the finery and
running-out furnaces now employed is lost by the conducting power of the
sides and bottom of the hearth; at the same time that the fluid metal
does not present a sufficient amount of surface to the ignited fuel to allow
of its being converted into steel or malleable iron while still retaining a
fluid state, as in the apparatus bercin-before described; and also in the
third arrangement of apparatus, which may be used for carrying into effect
my said Invention, and which consists in forming a furnace of a cylindrical
or spherical form, the outside shell being composed of boiler plate, lined
internally with fire bricks coated with loam; the furnace is to be mounted
on hollow horizontal axes, which are mounted in a suitable frame, so
that rotary motion may be communicated to the furnace. In the interior I
form several shelves or ribs, for the purpose of lifting up the fluid metal and
letting it fall again through the fuel, and so on continuously, until the refine-
ment of the iron is effected. It will be observed that those parts of the furnace

page_text: which at one part of its revolution form the roof, and are exposed to the
intense heat of the fuel, will at another part of the revolution form the bed on
which the chief portion of the metal rests; and hence, instead of there being a
continual loss of heat from the metal, from its absorption by the bed of the
furnace, there will be a constant accession of heat to the metal by the highly
heated interior surface of the furnace descending below the fluid metal, and
forming for the time the bed on which the metal rests. In some cases the
shelves may be dispensed with, which will allow the metal quictly to slide over
the highly heated surface of the interior of the furnace, the fuel floating on the
surface of the metal. In either case it will be understood that the axes of the
furnace will be made hollow, and of such. a diameter as to admit the blast
pipe at one end, while the opposite one is made large enough to admit the fuel
and metal, and at the same time serve as a means for the products of
combustion to escape."
.
The manner in which I carry into practical operation this part of my said
Invention will be better understood by reference to Sheet A of the Drawings
hereunto annexed, where Figure 1 is a longitudinal section, and Figure 2 a
cross section, of a cylindrical furnace, the axis of which is horizontal, and is
supported at each end on hollow trunnions B and C, which rest in standards
D. The outer shell of the furnaco A, I prefer to form of stout plate iron, with
one end made of cast iron, having the trunnion C formed upon it; around
its outer edge, I form a row of cogs, by means of which rotatory motion is
communicated to the furnace.through the pinion E and shaft F, which may bo
actuated by any first mover. The outer shell of the furnace A is lined with
fire bricks A', some of which are made to project inwards beyond the rest, as
shewn at A2, and thus form shelves or buckets, for the purpose of lifting up
the fluid metal and allowing it to fall again through the incandescent fuel.
G is-a-pipe through which the blast is conducted into the furnace, a closely
fitted joint being formed at G*, where the fixed end of the pipe G enters the
revolving hollow trunnion C. At the opening B the fluid crude metal intended
to be refined may be run into the furnace, and through this opening also a
supply of fuel may be thrown into the furnace from time to time, while it also
serves as a means of escape for the products of combustion. In using this
apparatus a fire is first to be lighted in the furnace, and a blast of air should
be conveyed from a blowing fan into it by means of the pipe G; the furnace
should then be put in motion, whereby the whole of its interior surface will
become highly heated. When the fuel. is in a state of vivid conibustion, and
the interior of the furnace is highly heated, a charge of fluid crude iron may
be poured or run in at the opening B; when it will be found that the projecting

page_text: parts A will lift up the portions of metal, and pour it into and among the
burning mass of fuel, and expose it to the action of the blast of air, whereby
its refinement will be effected, and its temperature raised, and which will be
further assisted by the highly heated interior surface of the furnace constantly
descending below the surface of the fluid metal, and thus for the time forming
the bed on which the metal rests. When the workman judges that the metal
has been sufficiently decarbonized for his purpose, he will stop the rotation
of the furnace, and proceed to discharge the fluid metal by opening the tap
hole H, which must be stopped with loam during the process, as commonly
practised in cupola furnaces used for remelting iron. This apparatus may
be modified so as to cause the fluid metal to slide quietly over the heated'
surface of the interior of the furnace, by omitting the projecting parts A³,
and thus forming a plain cylindrical furnace, as represented in cross section
at Figure 3, Sheet A, all the other arrangements of the apparatus being
the same as shown at Figures 1 and 2. Although the horizontal revolving
furnace, herein lastly described, has the advantage of always presenting a
newly heated surface for the metal to rest on, it nevertheless does not
present so large a surface of fluid iron to the action of the fire and to
the decarbonizing action of the blast, as may be obtained by causing the
furnace to revolve on a vertical axis in the manner herein-after described,
and which modification of furnace I prefer for the purpose of refining iron,
until so much of its carbon has been driven off as to give to the said crude
iron the properties of, or to convert it into, steel, or pure or nearly pure
refined iron. And here I would observe that for ordinary purposes coke may
be used for fuel for carrying into effect my said Invention, although I in all
cases when the quality of the metal is of great importance prefer to use
charcoal, wood, or prepared peat, as the effect of such last-named fuels are
less injurious to the metal than coke made from mineral coal.
In constructing furnaces to revolve on a vertical axis, the cylindrical
form is most suitable; the outside shell, being made of strong boiler plate
soundly rivitted, is to be lined with fire brick, and coated with loam,
the upper part being closed partly over, having a central hole at the
top of about one-third the diameter of the furnace; the bottom of the
furnace is formed of cast iron, strongly ribbed and keyed on to a spindle ;
the foot of this spindle rests in a foot-step sunk several feet below the
ground level, the upper part of the spindle, working in a bearing formed
in an iron frame secured to heavy masonry; this spindle has keyed upon
it a wheel, by which a rapid rotary motion is given to it. A fire having
been made in the furnace, and a powerful blast applied to it, either

page_text: through the centre of the furnace at bottom, or by nozzles at the sides,
which communicate with a hollow space around the axis; when the inte-
rior of the furnace is brought up to an intense heat the fluid iron may be
run into it, and a rapid motion communicated to the furnace, whereby the
fluid metal will rise up the sides of it as far as where the top closes over, and
be thore suspended by centrifugal force, the metal being distributed in a
cylindrical layer of a few inches only in thickness; the fuel and heated
vapours will by the same agency be pressed continually in contact with the
fluid metal, and act powerfully theroon. By diminishing and increasing
alternately the speed of the furnace, the metal will rise up or sink lower down
in the furnace, and thus afford constantly fresh surfaces to the action of the
firo and oxygen present in the furnace, which, by combining with the carbon
contained in the iron, will refine and purify it to the required extent. In some
cases; however, I find it preferable to introduce a fire-clay pipe into the fluid
metal in the bottom of the furnace, and by means of it force a current of hot
air into and among the fluid metal; when the metal is somewhat cooled, the
"pipe may be withdrawn, and the motion of the furnace continued until it has
been again heated up, when the process of blowing air or steam through the
fluid metal may be repeated; and here I would remark that hot or cold air
may be used, but I prefer hot blast, and that it should be heated to the highest
practicable limit. As soon as the complete refinement of the metal is effected;
the motion of the furnace may be discontinued, and the fluid steel or iron be
tapped out of the side of the furnace, as usually practised in cupola-furnaces
used for smelting iron; the metal so run out being received into suitable ingot
moulds, whereby blocks of metal will be formed suitable for hammering or
rolling into bars, plates, rails, or rods, and which may be either hard steel or
soft steel, hard iron or soft iron, according to the extent of the refining process.
And. here. I would observe, that when I-desire to-make-steel- of a superior
quality, I carry out the refinement of crude iron as far as possible, and produce
thereby soft iron, which I cast while in a fluid state into ingots, which I after-
wards roll into bars or rods of the desired form and size; the iron bars thus
formed I cement with charcoal, in tho manner already practised in making
blister steel; but the cemented bars made from cast ingots of iron will not
form blisters, in consequence of their freedom from iron scales. When the
[process of cementation has been carried to the desired extent, the bars are
removed from the cementing chest, and again rolled or tilted as already practised
in the manufacture of steel."
.
In order that this part of my said Invention may be fully understood, I have
hereunto annexed a Sheet of Drawings, marked B, on which a centrifugal

page_text: revolving furnace is shown; Figure 1 being a vertical section thereof, and
Figure 2 a horizontal section of the same.
a is the outer casing of the furnace, which I prefer to make of rivetted iron
plates; the bottom 6 of the casing is made of cast iron, and strengthened by
ribs b', which extend from the central boss 62, to the outer edge, and thus
affords a strong support for the furnace; c is a shaft, the top part of which is
keyed into the boss 63, its lower end resting in a brass foot-step or bearing
d; the upper part of the shaft c works.in brasses c, which are let into the
foundation plate f; this plate is of sufficient size to cover the vacant space g,
left in the foundation or masonry h; to this masonry it is securely fixed by
bolts i. A bevilled wheel j is keyed on the shaft c, by means of which a rotary
motion may be communicated from the bevilled wheel k, which is keyed
on an axis l, and which receives motion from a steam engine or other first
mover, and thus, when required, the whole apparatus may be put in motion.
The casing a is lined with fire brick coated with loam or other suitable refrac-
tory substance, the shape of which may be very accurately and easily, formed by a
moulding board or template, as practised in making the moulds in loam that aro
used in iron founding, the movement of the furnace on its axis c affording great
facility for this operation. The furnace thus lined up with loam may be con-
sidered simply as a revolving cupola or blast furnace, and should be supplied
with a powerful blast of air, which I prefer to be highly heated. In order to
keep up the communication with the blast while the furnace is in motion, I
form an annular chamber f* around the part occupied by the brasses e; below
the chamber f*, I attach the blast pipe m; a similar annular chamber is formed
at in the bottom plate 6 of the furnace casing, on the upper side of which
there is also formed a chamber b', having a central orifice, over which the
tuyere pipen is fixed, and thus a communication may be at all times kept up
between the blast pipe m and the tuyere pipe n, the air from the blast pipe
entering the lower part of the annular chamber f*, and passing through two
or more holes f' into the chamber b', and upwards through two or more holes
6' into the space b, and from thence into the tuyere pipe n; to prevent the
escape of air by the joint formed between the revolving plate 6 and the fixed
plate f, a packing ring is fitted to, the plate b, and is allowed to rest on tho
plate fat a part where its surface is raised and is made smooth and even.
The exterior of the pipen is defended by a coating of loam, with which the
lower cavity p of the furnace is also formed; above the mouth of the tuyere
pipe is a dome-shaped fire tile r, having several holes passing through it in
direction upwards, and at such an angle as to direct the blast which passes
through them upon the surface of the fluid metals, which is shown as occupying

page_text: a sunk channel, extending entirely around the inside of the furnace. The action
of the apparatus is as follows: Some lighted fuel is first put upon the tile
and good hard coke or charcoal is put upon it; a moderate blast is then applic
through the pipe m, so as to bring up the heat of the furnace gradually; mor
fuel is added, and the full power of the blast put on, so as to bring the interio
surface of the furnace up to the highest degree of heat attainable; the shaft
is then put in motion, carrying with it the blast or cupola furnace. A spout
is then put into the open mouth of the furnace, its lower curved end being
placed near the conical part of the lining v, as shown in Figure.1; crude iron
in a fluid state is then allowed to flow into the spout u, which will direct the
stream of fluid iron against the conical part v, the metal will thereby be caused
to rotate with the furnace, and will require so much centrifugal force as to
keep it in close contact with its. interior surface; in its tendency to fly further
from the centre of motion, it will pass down the conical part v, and be collected
in the cavity s, as shown in the Drawings, where it is to be suspended during
the decarbonizing process; the spout u is then to be removed, and a powerful
blast is to be kept up; the air issuing from the orifices will produce an
intense ignition at a number of points near the surface of the metal. It will
be understood that a slight. alteration of the speed of rotation will cause a
movement of the fluid particles, and thus constantly bring fresh portions of the
fluid zone.of.metal to the inner surface, and exposo all parts in turn to the
decarbonizing action of the blast. The centrifugal force operating to keep
the metal suspended will drive the fuel in close contact with it, and also carry
the currents of heated vapour as far outward as possible, and thus cause them
to impinge continually on the surface of the fluid metal. By this means the
intense heat required to maintain steel or pure iron in a molten state will
be obtained and applied to the large surface of metal exposed.. Whenever
the process has arrived at the desired point, the blast may be shut off, and tho
rotation of the furnace stopped; the metal will then rush downward and pass
through the holes into the chamber p, where it will accumulate. On one
side of the furnace there is a tapping hole, not shown in the Drawings, but
made precisely similar to the tapping holos of an ordinary cupola or blast
furnace; this hole is to be quickly opened, and the fluid metal allowed to flow
out into moulds, as required; the tap hole may then be closed with loam and
secured with an iron strap, the. blast turned on, and the furnace recharged
with metal, as before described, so as to produce a repetition of the process:
The charging on of the fuel from time to time may take place while the
furnaço is in motion, for as the fuel becomes consumed, the centrifugal action
of the furnace will cause fresh portions of it to leave the central part, so that

page_text: a vacant space will be left for fresh fuel, which will fall: into the centre, and
thus, the influx of cold fuel will not affect the high temperature required at
those parts in close proximity to the fluid metal:. In this particular form of
apparatus the metal should not be let down into the lower part of the furnace
until it is ready to be discharged, because the chamber p. is too cold to allow
it to remain in the fluid state. I therefore sometimes construct the centrifugal
blast furnace as represented at Figures 3 and 4, which show so much of the
furnace. as will enable this particular modification of it to be understood.
In the vertical section, Figure 3, I have shown two passages A, A, formed
on opposite sides of the bottom.plate of the furnace; these passages continue
upwards at A, and terminate in tuyere pipes B, which enter the. furnace on
two opposite sides, as shown in the cross section at Figure 4; on the passages
A there are small doors C, by means of which access. may be had to the
interior of the furnace, if necessary.
.:
It will be observed that the tuyere. pipes are surrounded by a mound. of
loam D, which serves to protect the pipes from the too violent action of the
heat, and to prevent the metal from entering the tuyeres when the furnace is
first set in motion; the metal in that case will rise upward at those parts
furthest from the centre, passing up by the sides but not in front of the
mounds D. When this modification of the apparatus is used, the furnace is
to be heated as much as possible, the fluid. iron is then run in among the fuel,
and will thus. rapidly find its way to the lower part E of the furnace, as slown
in the Drawings; the blast from the tuyeres being directed on to its surface, a
partial refinement of the metal will soon take place, which, however, cannot be
carried very far,.or the metal would become solidified. While the partial decar-
bonization of the metal has been going on, the surface of the sunk channel G
will have become intensely heated; the furnace is then to be put in motion
in the manner herein-before described in reference to Figure 1. The fluid
metal in the lower part E of the furnace will thus be made to revolve, when
the centrifugal force which its particles acquire by rotation will cause it to
ascend, the inclined sides of. the furnace,. and accumulate in the space G, where
it. will, evenly distribute itself, and remain suspended so long as the proper
speed of the apparatus is. kept up.. . While occupying this position it will
become intensely heated and still. further decarbonized. Meanwhile the
hearth. or sole of the furnace will have. again been heated. The rotation of
the furnace may then be stopped, when the. metal will. again sink down and
occupy. the lower E of the furnace, the metal resting on the newly heated
surface of. the. hearth, and will thus.again be brought under the direct and
powerful decarbonizing action of the blast.. In this way the. alternate rising
part

page_text: up and lowering down of the charge of metal may take place until the desire
amount of decarbonization or refinement has been effected. The state of the
metal may be ascertained from time to time to time by letting out a smal
quantity of it by the tap hole, which is made in the side of the furnace, a
before described in reference to Figure 1. When the metal is required to
form steel, I put into the furnace during the process of refining about one o
two per cent. of oxide of manganese and one or two per cent. of commor
salt and of potashes, and one per cent. of lime when coke is use as fuel
but when charcoal is used, I omit the potashes, because the ashes or residuum
of charcoal will form a sufficient flux without the use of potashes; and wher
the refinement of the iron is desired to be carried to the extent of depriving
the metal of its carbon as far as practicable, and thus produce soft malleable
iron, I entirely omit the use of manganese, using lime and salt only as a flux
when charcoal is used as fuel, and lime and potashes when coke is used.
When the crude iron to be refined contains sulphur, I pass jets of steam
through the fluid metal. The steam is thus decomposed, producing both
oxygen and hydrogen gas; the latter combines with the sulphur, and carries
it off in the form of sulphuretted hydrogen, while the oxygen gas combines
with the carbon of the crude iron, producing combustion accompanied by the
disengagement of carbonic acid gas or carbonic oxide. When, however, the
decarbonization of the metal is the chief object sought, atmospheric air may
be used in lieu of steam, or the two may be used together. One of the
modes by which this may be carried into effect in the centrifugal blast furnace
is represented at Figure 5, on the annexed Sheet of Drawings, which is a
vertical section taken through the centre of the furnace, and Figure 6 is
a horizontal section of the same. The general arrangement of the furnace
and the mode of driving it are the same as herein-before described in reference
to Figure 1. The steam or air intended to be forced into or through the fluid
metal is conveyed from an air forcing pump or from a steam boiler up the
central axis N, which is made tubular for that purpose, the lower end of it
passing through a suitable stuffing box formed on the air or steam pipe. The
bottom plate of the furnace casing has two passages P formed in it, which
communicate with the hollow axis N in the centre, and with the elbow pipes
Q. Around the exterior of the outer casing R of the furnace is a circular
chamber S, to which the pipes Q, Q, are attached, so that a communication
may at all times be kept up between the air pump or steam boiler and the
space or chamber S. On the interior of the casing R there are small flange
rings T, arranged in rows of three at several different parts of its circum-
ference. Into these angle rings are fitted small conical pieces of well-baked

page_text: fire clay U, having a small opening through them. They are made secure
by red lead or other cement, and kept in place by a screw plug V, which is
secured into the chamber S. These plugs are hollow, and have cross passages
formed in them so as to admit the air or steam freely to the hole in the small
fire cones U, which can be removed at any time by unscrewing the plug
V. It will be observed that the cones of fire clay do not extend quite
through the lining of the furnace, which is made to enclose them so as to
present only their smallest end to the action of the metal. When this modi-
fication of my Invention is used, the fire is made in the interior, as before
described in reference to Figure 1, the blast being supplied by two tuyero
pipes, which are arranged in a similar manner to that shewn in Figure 3,
but which are not seen in Figure 5 in consequence of their being formed at
right angles to the passages P, P; the orifice of one of them is, however,
shewn at W, Figure 5, and at W, W, Figure 6. By means of the blast from
the tuyeres W, the requisite amount of heat may be obtained to keep up the
fluidity of the metal during the decarbonizing or refining process. It will be
understood that the pressure of the steam or air forced through the holes in
the cones U must always exceed the pressure exerted by the centrifugal force
of the metal over a given area, in order to prevent any of the metal from
entering the cones. It will be necessary that the air or steam should always be
turned on previous to giving motion to the furnace. When air alone is userl,
it may be allowed constantly to blow through them, as these numerous small
though powerful jets will cause an intenso combustion at the exterior parts of
the cylindrical mass of fuel, and thus heat the interior surface of the furnace
to a very high temperature, in contact with which the metal will be forced
whenever the furnace is put in motion at the required velocity.
Having thus described my Invention, and the manner in which the same
may be carried into effect, I desire it to be understood that I do not confino
myself to the precise details herein specified, provided that the peculiar
character of my Invention be retained; but what I do claim, firstly, is the
conversion of fluid crude iron into steel or into malleable iron by exposing
the metal to the decarbonizing action of currents of air in furnaces, through
which the metal is allowed to fall for that purpose. And also in the manu-
facture of iron and steel, the alternate rising and lowering of two furnaces, so
as to allow the fluid metal to flow from one to the other in the manner and
for the purposes before described.
Secondly, I claim, in manufacturing malleable iron and steel from crude
iron while still in a fluid state, the use of revolving furnaces, having apparatus
in the interior for the purpose of elevating portions of the metal, and allowing

page_text: it again to fall in streams or showers when exposed to the action of currents
of air passing through the furnace.
Thirdly, I claim, in the manufacture of iron and steel, the suspension of
the fluid metal in a furnace by means of centrifugal force generated by the
rotation of such furnace, and the forcing into, through, or upon the fluid
metal so suspended currents of air or steam...
Lastly, I claim the manufacture of bars, rods, or plates of steel by the
cementation of bars or rods of malleable iron that have been obtained by
the direct conversion of crude iron into malleable iron, and while still in a
fluid state cast in suitable-moulds.:
In witness whereof, I, the said Henry Bessemer, have hereunto set my
hand and seal, this Fourth day of July, in the year of our Lord
One thousand eight hundred and fifty-six.
Witness,
GEO. PITT,
4, Old Square.
HENRY BESSEMER. (L.B.)