IMPROVEMENTS IN THE CONSTRUCTION AND MODE OF WORKING BLAST FURNACES EMPLOYED FOR SMELTING THE ORES OF IRON, AND IN THE MODE OF EMPLOYING AND UTILIZING THE GASEOUS PRODUCTS OF SUCH FURNACES, AND ALSO IN THE CONSTRUCTION AND MODE OF WORKING BLAST ENGINES EMPLOYED TO FORCE AIR INTO BLAST AND OTHER FURNACES
Year: 1869

page_text: LETTERS PATENT to Henry Bessemer, of Queen Street Place, Cannon
Street, in the City of London, for the Invention of "IMPROVEMENTS
IN THE CONSTRUCTION AND MODE OF WORKING BLAST FURNACES EMPLOYED FOR
SMELTING THE ORES OF IRON, AND IN THE MODE OF EMPLOYING AND UTILIZING
THE GASEOUS PRODUCTS OF SUCH FURNACES, AND ALSO IN THE CONSTRUCTION
AND MODE OF WORKING BLAST ENGINES EMPLOYED TO FORCE AIR INTO
BLAST AND OTHER FURNACES."
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 CONSTRUCTION AND MODE OF WORKING BLAST FURNACES
EMPLOYED FOR SMELTING THE ORES OF IRON, AND IN THE MODE OF EMPLOYING AND
UTILIZING THE GASEOUS PRODUCTS OF SUCH FURNACES, AND ALSO IN THE CON-
STRUCTION AND MODE OF WORKING BLAST ENGINES EMPLOYED TO FORCE AIR INTO
BLAST AND OTHER FURNACES," to be as follows:

page_text: The outer shell or case of the furnace which for the purposes of my
Invention I make of very strong plate iron or steel, and which extends
from below the bottom of the hearth up to the crown or top of the
furnace, there uniting with the metal ring which, forms the mouth of the
furnace, and thus encasing the whole of the fire-brick or stonework which
constitutes the furnace, suitable openings being left in the shell for the
purposes herein-after referred to. I prefer to make the shell in separate
rings or sections united by stout flanges by means of which the several
portions are firmly united, the whole being as far as needful strengthened
by hoops, angle ribs, or T-irons securely rivetted to the plating, the
general structure being further supported on cast-iron or rivetted plate-
iron columns surrounding the lower part, all the joints of the shell being
well caulked and capable of resisting an internal pressure of 20 or more
pounds per square inch on the whole internal surface of the furnace.
Into this furnace I force air by a suitable blast engine through several
tuyeres or openings used in lieu of tuyeres, employing, by preference, a
pressure varying from 10 to 20 lbs. per square inch, and I retain in such
furnaces the gaseous products of combustion at a pressure-preferably of
about three or four pounds on every square inch less than the pressure of
the blast in each case, thus obtaining an available pressure of three or
four pounds per square inch to cause the blast to force its way through
the charge of materials. The blast furnace so arranged I call by way of
distinction a high-pressure blast furnace.
The method in which I prefer to confine the gases in the furnace until
sufficient pressure is attained is herein-after described-In consequence
of the pressure thus employed the temperature of the gaseous products
of combustion will be greatly increased, and I am thereby enabled to
dispense with the whole of stoves, pipes, and furnaces generally em-
ployed for heating the blast although the high pressure blast furnace
may if desired be worked with hot instead of cold blast. In some cases
it may be found desirable to lower the temperature of the gaseous
products of combustion after they have left the blast furnace to some
extent, and then this may be done by causing the hot gaseous products
to envelope or come in contact with the pipes which convey the blast to
the furnace, and thus a certain amount of heat may be readily trans-
mitted to the air circulating through them.
The arrangements for feeding in the fuel, ore, and fluxes at the top of
the furnace must be such as to effect this object without allowing much

page_text: of the gases to escape if the cup and cone arrangement be employed, or
if a piston be used in lieu thereof to close the furnace, I in either case
continue the sides of the cup vertically upward, forming thereby a strong
plate iron cylinder having a cover into which another cone or piston is
fitted, thus making the cylinder into a close chamber. A feeding floor
or stage may be made at a level with the upper cone or piston valve.
When feeding the furnace I lower the upper valve and put the requisite
charges of ore and fuel into the cylinder and then close the upper valve,
after which I open the lower one and allow the material to fall into the
furnace, thus losing a cylinder full of the compressed gases at every such
discharge of fuel into the furnace. The joints of the cone or piston valve
or other joints may be prevented from leaking gases outwardly by the
employment of air or steam of greater pressure introduced between the
joints or valve fittings, and the metal work constituting all such valves,
cones, or valve seats may be kept from injury by heat, by coring, or
otherwise forming therein passages for the circulation of water, such
parts may also be made to receive less heat by conduction by using thin
thin fire-tiles or other slow conducting materials between the flanges
which unite them to other parts which are unavoidably made very hot.
My Invention also consists in economizing fuel in blast furnaces by
preventing so large an escape of carbonic oxide gas at the upper part of
the furnace as usually takes place. The bulk of the air entering the
furnace should on meeting the incandescent fuel be at once converted
into carbonic acid gas mixed with nitrogen, in passing upward among the
fuel carbonic acid gas is converted for the most part into carbonic
oxide gas, and in this state is in part utilized in the reduction of the ore,
but a very large quantity escapes from the furnace still in the condition
of carbonic oxide, thus robbing the furnace of a large amount of
expensive fuel. To avoid this loss I do not allow all the carbonic acid
gas formed to pass up the furnace, but draw off a portion of it at a low
level in the furnace allowing the remainder only to pass up the furnace
to become converted into carbonic oxide to reduce, the orc.
working in this way with a high pressure blast furnace I make openings
in the outer wall of the furnace leading into an annular flue or other
flues, the opening from the furnace into the flue by means of which a
portion of the escape from the furnace takes place should be of consider-
able size so that there may be a comparatively gentle current out of the
furnace. The escape from the flue may be by an aperture so contracted
When

page_text: as to allow only a portion of the gases of the furnace to pass off through
this flue. I make these openings at such a height as I find best adapted
to let out the first products of combustion in the form of carbonic acid
gas. Now if we suppose a furnace working so that no carbonic acid gas
escaped from the mouth of it, the whole having been converted into
carbonic oxide it will be understood that in such a case all the carbonic
acid gas that may be let out at the lower part of the furnace will prévent
the destruction of as much fucl as would have been absorbed by its
conversion into carbonic oxide on its passage up through the mass of
fuel. By thus letting out a portion of the gas below that portion tra-
versing the fuel in the upper part of the furnace will have a much larger
surface of carbon to act upon in proportion to its volume than it would
have if the whole of the gases had been passed upwards, while the high
temperature consequent of the pressure of the gases should not only
facilitate the rapid conversion of the reduced quantity of carbonic acid
into carbonic oxide, but should also effect a rapid deoxidation of the
porous oxides of iron so subjected to heat and pressure. The tap hole
and tynip may be enclosed in an air-tight chamber into which air under
pressure is admitted in such quantities as to render the pressure of the
air in the chamber so nearly in equilebrium with the gases in the furnace
as to prevent any violent outflow of gases at the tynip although the
running out of the cinder may be allowed to go on continuously. When
the workmen require to clear a passage for the cinder or approach the
tap hole for other purposes the pressure in the chamber may be so far
increased for the time as to cause the air from the chamber to enter
the furnace and thus entirely prevent the escape of any flame or gases
by this opening. Small chambers may in some cases be made to enclose
each tuyere, or the whole of the lower part of the furnace may be
enclosed in one large chamber into which the blast may be forced and
from which simple openings much larger than ordinary tuyeres may
enter the furnace and the tuyeres and pipes be thus dispensed with;
the openings used in lieu of tuyeres will be thus always accessible to
the workmen who may pass in and out of the chamber through closely
fitting doors, the chamber or chambers may be lighted and the air may
be cooled before entering them in the manner described in a Provisional
Specification bearing even date herewith for "Improvements in the Con-
struction and Mode of Working Furnaces and Apparatus employed in
and Using Malleable or Wrought Iron and Steel, and Pig or other Car-
burets of Iron, and Obtaining Cast Steel or Homogeneous Malleable

page_text: Iron therefrom," the cinder flowing from the furnace may descend
through an opening in the floor of the chamber into a waggon enclosed in
another small chamber below the first-named one a small quantity of
air may be allowed to escape from the slag chamber, and thus a current
of air will flow through the hole with the slag and prevent it from
heating the upper chamber.
In some cases it may be found desirable to place the tuyeres or the
openings used in lieu thereof at a higher level than usual, and in that
case allow the carbonic acid gas to escape at suitable openings below
the level of the tuyeres, such as at the tymp, which may form one
outlet, a similar one being formed at the opposite side; and although
I have described simple openings for the escape of gas and for inlet of
blast such openings may in some cases extend so far round the lower
part of the furnace as to form more or less completely annular passages
communicating with the interior of the furnace all round.
My improvements also consist in a mode of preventing the decar-
buration of the metal by the blast after fusion and facilitating its further
carburation after leaving the blast furnace. For this purpose I lessen
the capacity of the hearth and form a much smaller passage than is now
used to conduct the metal to the tap hole, using in lieu thereof a small
inclined channel or pipe through which both the metal and slag may
flow from the furnace continuously, and as quickly as they come down
some portion of the flame or heated products of combustion escaping
down the passage through which the metal flows. I collect or receive
the metal in a heated vessel more or less completely filled with incan-
descent coke for the purpose of keeping it fluid, and further carburizing
it in the manner described in a Provisional Specification bearing even
date herewith for "Improvements in the Treatment of Crude or Pig
Iron and other Carburets of Iron, and in the Apparatus employed for
such Purposes." The gaseous products of combustion may be conveyed
from the top of the furnace down to the land level by a large vertical
pipe on the top of which a close cistern is fitted; the lower side of the
cistern being perforated with small holes through which a shower of
water in a finely divided state is caused to flow by a pump attached to
the blast engine, whereby the quantity of water injected may be
regulated, by this means, the highly heated gases may be cooled down
and mixed with steam arising from the evaporation of the injected
shower of water for the purpose of forcing the blast into high-pressure

page_text: furnaces when used for smelting iron ores, as in the Invention herein
described, and also when employed for forcing blast under pressure into
furnaces employed in fusing malleable or wrought iron and steel, and
other carburets of iron.
I employ the gaseous products of such high-pressure furnaces when
cooled down with water, or otherwise, for giving motion to a hot-air
blast engine in which the said gaseous products (in combination with
the steam produced in the cooling process) is made to act in a direct-
acting blast apparatus. I prefer to arrange the air cylinder and the gas
cylinder in a line with one piston rod connected to both pistons; I
prefer to use either piston valves or double heat equilibrium valves both
for air and gas cylinders, each of which I line with a plain shell of hard
metal so made and fitted between the covers as to readily be removed
and exchanged for a similar one when too much worn for use. The air
so forced is conveyed into a receiver having two diaphragms dividing it
into three compartments which communicate with each other by small
openings and thus tend much to equalize the blast. A fly wheel and
crank is employed to regulate the motion of the engine; and one or more
valves are employed to regulate the pressure of the gases and prevent the
prevent the pressure from exceeding the proper limit. It will thus be
seen that the high pressure furnace to whatever purpose it is applied
may be supplied with blast at the pressure desired without employing
boiler power and fuel for that purpose, the high pressure furnace itself
furnishing all the power necessary for this purpose without burning the
gases in other furnaces to obtain power through the agency of steam.
The escaping carbonic acid gas from the lower part of the furnace may
be conducted also to the blast engine, or it may be used to work the
winding engine, or the heat thus escaping may be employed to burn the
lime or roast or dry the orc or fuel employed.
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.

page_text: 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. 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 CONSTRUCTION AND MODE OP WORKING BLAST FURNACES EMPLOYED FOR
SMELTING THE ORES OF IRON, AND IN THE MODE OF EMPLOYING AND UTILIZING
THE GASEOUS PRODUCTS OF SUCH FURNACES, AND ALSO IN THE CONSTRUCTION AND
MODE OF WORKING BLAST, ENGINES EMPLOYED TO FORCE AIR INTO BLAST AND
OTHER FURNACES," 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
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:-
The outer shell or case of the furnace which for the purposes of my
Invention I make of very strong plate iron or steel, and which extends
from below the bottom of the hearth up to the crown or top of the
furnace, there uniting with the metal ring which forms the mouth of
the furnace, and thus encasing the whole of the fire-brick or stonework
which constitutes the furnace, suitable openings being left in the shell
for the purposes herein-after referred to. I prefer to make the shell in
separate rings or sections united by stout flanges, by means of which the
several portions are firmly united, the whole being as far as needful
strengthened by hoops, angle ribs, or T-irons securely rivetted to the
plating, the general structure being further supported on cast iron or

page_text: rivetted plate iron columns surrounding the lower part, all the joints
of the shell being well caulked and capable of resisting an internal
pressure of 20 or more pounds per square inch on the whole internal
surface of the furnace. Into this furnace I force air by a suitable blast
engine through several tuyeres or openings used in lieu of tuyeres,
employing, by preference, a pressure varying from 10 to 20 lbs. per
square inch, and I retain in such furnaces the gaseous products of com-
bustion at a pressure preferably of about 3 or 4 pounds on every square
inch less than the pressure of the blast in each case, thus obtaining an
available pressure of three or four pounds per square inch to cause the
blast to force its way through the charge of materials, the blast furnace
so arranged I call by way of distinction a high-pressure blast furnace..
The method in which I prefer to confine the gases in the furnace
until sufficient pressure is attained is herein-after described. In; con-
squence of the pressure thus employed the temperature of the gaseous
products of combustion will be greatly increased, and I am. thereby
enabled to dispense with the whole of stove pipes and furnaces
generally employed for heating the blast, although the high-pressure
blast furnace may, if desired, be worked with hot instead of cold blast.
In some cases it may be found desirable to lower the temperature
of the gascous products of combustion after they have left the blast
furnace; to some extent this may be done by causing the hot gascous
products to envelope or come in contact with the pipes which convey
the blast to the furnace, and thus a certain amount of heat may be
readily transmitted to the air circulating through them.
The arrangements for feeding in the fuel, ore, and fluxes at the top
of the furnace must be such as to effect this object without allowing
much of the gases to escape if the cup and cone arrangement be employed,
or if a piston be used in lien thereof to close the furnace, I in either
case continue the sides of the cup vertically upward, forming thereby a
strong plate iron cylinder having a cover, into which another cone or
piston is fitted, thus making the cylinder into a close chamber; a feeding
floor or stage may be made at a level with the upper cone or. piston
valve. When feeding the furnace I lower the upper valve and put
the requisite charges of orc and fuel into the cylinder, and then close
the upper valve, after which I open the lower one and allow the material
to fall into the furnace, thus losing a cylinder full of the compressed
gases at every such discharge of fuel into the furnace; the joints of the

page_text: cone: .or. piston valve. or other joints may be prevented from leaking
gases outwardly by the employment of air or steam of greater pressure
introduced between the joints or valve fittings, and the metalwork
constituting all such valves, cones, or valve seats may be kept from
injuryǝby heat by .coring or otherwise forming therein passages for the
circulation of..water, such parts may also be made to receive less heat
by conduction by using thin fire tiles or other slow conducting materials
between the flanges which unite them to other parts which are
unavoidably made very hot.
My Invention also consists in economizing fuel in blast furnaces by
preventing so large an escape of carbonic oxide gas at the upper part
of the furnace as usually takes place. The bulk of the air entering
the furnace should on meeting the incandescent fuel be at once converted
into carbonic acid gas mixed with nitrogen in passing upward among
the fuel; this carbonic acid gas is converted for the most part into
carbonic oxide gas, and in this state is in part utilized in the reduction of
the ore, but a very large quantity escapes from the furnace still in the
condition of carbonic oxide, thus robbing the furnace of a large amount
of expensive fuel. To avoid this loss I do not allow all the carbonic
acid gas formed to pass up the furnace but draw off a portion of it at a
'low level in the furnace allowing the remainder only to pass up the
furnace to become converted into carbonic oxide to reduce the ore.
When working in this way with a high-pressure blast furnace I make
openings in the outer wall of the furnace leading into an annular fluc or
other flues; the opening from the furnace into the flue by means of
which a portion of the escape from the furnace takes place should be
of considerable size so that there may be a comparatively gentle current
out of the furnace. The escape from the flue may be by an aperture
so contracted as to allow only a portion of the gases of the furnace to
pass off through this fluc. I make these openings at such a height as
I find best adapted to let out the first products of combustion in the
form of carbonic acid gas. Now, if we suppose a furnace working so
that no carbonic acid gas escaped from the mouth of it, the whole having
been converted into carbonic oxide, it will be understood that in such a
case all the carbonic acid gas that may be let out at the lower part of
the furnace will prevent the destruction of as much fuel as would have
been absorbed by its conversion into carbonic oxide on its passage up
through the mass of fuel. By thus letting out a portion of the gas

page_text: below that portion traversing the fuel in the upper part of the furnace
it will have a much larger surface of carbon to act upon in proportion
to its volume than it would have if the whole of the gases had been
passed upwards, while the high temperature consequent on the pressure
of the gases should not only facilitate the rapid conversion of the
reduced quantity of carbonic acid into carbonic oxide, but should also
effect a rapid deoxidation of the porous oxides of iron so subjected to
heat and pressure.
The tap hole and tymp may be enclosed in an
air-tight chamber, into which air under pressure is admitted in such
quantities as to render the pressure of the air in the chamber so nearly
in equilibrium with the gases in the furnace as to prevent any violent
outflow of gases at the tymp, although the running out of the cinder
may be allowed to go on continuously. When the workman require to
clear a passage for the cinder or approach the tap hole for other purposes
the pressure in the chamber may be so far increased for the time as to
cause the air from the chamber to enter the furnace and thus entirely
prevent the escape of any flame or gases by this opening. Small
chambers may in some cases be made to enclose cach tuyere, or the
whole of the lower part of the furnace may be enclosed in one large
chamber, into which the blast may be forced, and from which simple
openings much larger than ordinary tuyeres may enter the furnace, and
the tuyeres and pipes be thus dispensed with, the openings used in lieu
of tuyeres will be thus always accessible to the workmen who may pass
in and out of the chamber through closely fitting doors. The chamber
or chambers may be lighted and the air may be cooled before entering
them in the manner described in a Specification bearing even date here-
with for "Improvements in the Construction and Mode of Working
Furnaces and Apparatus employed in Fusing Malleable or Wrought
Iron and Steel, and Pig or other Carburets of Iron, and Obtaining Cast
Steel or Homogeneous Malleable Iron therefrom," and numbered 1432.
The cinder flowing from the furnace may descend through an opening
in the floor of the chamber into a waggon enclosed in another small
chamber below the first-named one, a small quantity of air may be
allowed to escape from the slag chamber, and thus a current of air will
flow through the hole with the slag and prevent it from heating the
unner chamber

page_text: in that case allow the carbonic acid gas to escape at suitable
openings below the level of the tuyeres, such as at the tymp which may
form onc outlet, a similar one being formed at the opposite side, and
although I have described simple openings for the escape of gas and for
inlet of blast such openings may in some cases extend so far round the
lower part of the furnace as to form more or less completely annular
passages communicating with the interior of the furnace all round.
My improvements also consist in a mode of preventing the decar-
buration of the metal by the blast after fusion, and facilitating its
further carburation after leaving the blast furnace. For this purpose I
lessen the capacity of the hearth and form a much smaller passage than
is now used to conduct the metal to the tap hole, using in lieu thereof
a small inclined channel or pipe through which both the metal and
slag may flow from the furnace continuously and as quickly as they
come down, some portion of the flame or heated products of combustion
I collect or
escaping down the passage through which the metal flows.
receive the metal in a heated vessel more or less completely filled with
incandescent coke for the purpose of keeping it fluid and further
carburizing it in the manner described in a Specification bearing even
date herewith for "Improvements in the Treatment of Crude or Pig
Iron and other Carburets of Iron, and in the Apparatus Employed for
such Purposes," and numbered 1434. The gaseous products of com-
bustion may be conveyed from the top of the furnace down to the land
level by a large vertical pipe, on the top of which a close cistern is
fitted, the lower side of the cistern being perforated with small holes
through which a shower of water in a finely divided state is caused to
flow by a pump attached to the blast engine, whereby the quantity of
water injected may be regulated, by this means the highly heated gases
may be cooled down and mixed with steam arising from the evaporation
of the injected shower of water..
For the purpose of forcing the blast into high-pressure furnaces when
used for smelting iron ores, as in the Invention herein described, and
also when employed for forcing blast under pressure into furnaces
employed in fusing malleable or wrought iron and steel and other
carburets of iron, I employ the gaseous products of such high-pressure
furnaces when cooled down with water or otherwise for giving motion
to a hot air blast engine in which the said gaseous products (in com-
bination with the steam produced in the cooling process) is made to

page_text: act in a direct-acting blast apparatus. I prefer to arrange the air
cylinder and the gas cylinder in a line with one piston rod connected to
both pistons; I prefer to use either piston valves or double beat equi-
librium valves both for the air and gas cylinders each of which I line
with a plain shell of hard metal so made and fitted in between the covers
as to readily be removed and exchanged for a similar one when too
much worn for usc. The air so forced is conveyed into a receiver
having two diaphragms dividing it into three compartments which
communicate with each other by small openings and thus tend much
to equalize the blast. A fly wheel and crank is employed to regulate
the motion of the engine, and one or more valves are employed to
regulate the pressure of the gases and prevent the pressure from
exceeding the proper limit. It will thus be seen that the high-
pressure furnace to whatever purpose it is applied may be supplied
with blast at the pressure desired without employing boiler power
and fuel for that purpose, the high-pressure furnace itself furnishing
all the power necessary for this purpose without burning the gas in
other furnaces to obtain power through the agency of steam. The
escaping carbonic acid gas from the lower part of the furnace may be
conducted also to the blast engine, or it may be used to work the wind-
ing engine, or the heat thus escaping may be employed to burn the lime,
to roast or dry the ore or fuel employed.
And in order that this mode of constructing and working blast
furnaces may be fully understood I have hereunto annexed a Sheet
of Drawings on which the same is represented in vertical section at
Figure 1, and in elevation at Figure 2; Figure 3 is a cross section taken
at two different heights on the crooked line A, B, and Figure 4 is a
vertical section of the pipe for conveying the furnace gases to the blast
engine, the same letters are used in cach Figure to denote a repetition of
that part.
a is the outer shell or case of the furnace, which encloses the whole of
the masonry or brickwork; this case may be further strengthened by
hoops or angle flanges of iron or steel, so as to render it capable of
withstanding safely an internal pressure from one to two atmospheres in
excess of the external atmospheric pressure; the slope of the boshes is
similarly encased in a cone of plate metal a*, the base of the cone being
further strengthened by the iron band b; the outer shell of the furnace
slopes down to the ground level all round the furnace, as shown at a',

page_text: the
and also beneath it, as shown at a³, an annular space or chamber c is
enclosed around the boshes, the partitions a dividing this space into
two chambers c and c*. A strong box girder d, with central web,
extends entirely around the under side of the outer wall of the furnace,
and at intervals rests on strong iron webbed columns e, which occupy
the chamber c, resting below on the bed or foundation of masonry f.
Two small ante-chambers g and h, are made with two doors, each for
purpose of affording entrance and exit for the workmen from or into
the chambers c and c* at all times when required, notwithstanding that
the air in these chambers is greatly in excess of the external atmospheric
pressure, and which mode of gaining access to and egress from closed
chambers is fully described in a Patent bearing even date herewith, and
numbered 1432, and consequently does not form part of the present
Invention. Below the level of the tymp I form an arched chamber i,
into which a truck or carriage can be moved on rails for the purpose of
receiving the cinder flowing from the furnace, or the cast of metal may
be run into a moveable receptacle so placed; this chamber i is provided
with a well-fitted sliding door, made as near as may be air-tight; a little
leakage of air from the chamber i is however preferable as it will cause
an outward flow of air from the chamber c* through the hole j, and
An
thus prevent the ascent of heated fumes from the chamber i.
annular flue m is formed around the furnace, into which several passages
n lead from the furnace. At any part of the flue m a restricted outlet
may be made, of such a size as will allow the desired amount of carbonic
acid gas to escape while the rest of the gas passes upward and is con-
verted into carbonic oxide, and in that state deoxidises the ore, but with-
out taking up as much carbon as the whole of the gases would do if
allowed to pass upward among the fuel. The area of the escape open-
ings n are each so greatly in excess of the area of the one restricted outlet
as to cause a very slow and gentle current of gas to pass up them, and
thus not tend to carry out any fuel by these passages. Man-holes for
clearing out dust if necessary, can be made in the flue m, and if found
desirable that portion of the carbonic acid gas allowed to escape by these
passages from the furnace may be taken off at a much lower level than
that shown in the Drawings, the outlets n being in that case much
nearer to the level of the tuyeres, and communicating with a passage or
passages which pass out through the chamber c.
At the top of the
furnace I have shown a cup valve p, which forms the lower portion of
the chamber g; the upper part of this chamber is fitted with a second

page_text: conc r, through the centre of which the rod s of the cone p passes, the
cone having a jointed sling to support it, and allow it to be balanced
in the usual way and raised or lowered as required, the cone p also
having a separate arrangement of the same kind, so that each of the
cones p and r may be moved independently of each other, and so that
the ore and fuel may be admitted to the chamber 7 by lowering the
cone, while the cone p is closed after the materials are thus admitted
to the chamber 7. The workman will raise the cone and lower the
cone 2, by which means the materials will fall into the furnace, the
rising of the conc p and the lowering of the cone will allow another
charge to enter the chamber, and so on, a chamber full of gas being
allowed to escape at each operation of filling. I would observe that in
all cases before the cone p is lowered that an equilibrium of pressure
must be effected between the chamber and the inside of the furnace;
for this purpose a valve, not shown in the Drawings, is provided, by
means of which the workman may admit the furnace gases or steam into
the chamber 1, and thus equalize the pressure above and below the
cone 2, and so also before lowering the cone he will allow such steam
or gases to escape by a valve into the external atmosphere, in that case
equalizing the pressure above and below the cone 1. It is desirable
that the fitting surfaces of these valves should be more perfect than
usual, the metal parts being defended, if necessary, from the action of
oscaping gases by the passage of steam into the joint in a manner similar
to that by which the leakage of flame and heated gases are prevented
from escaping from the doors of high-pressure melting furnaces by the
use of air under pressure, as fully described in a Patent granted to me
and bearing date the 10th day of November 1868, and numbered 3419 The
gases after passing up through the materials in the furnace find their
escape by the openings t, and pass into an annular channel u, and from
thence into a large pipe w shown in vertical section at Figure 4, where
a portion of the side of the furnace is also shown, to render the position
of the pipe w and its connection with the channel u more clearly under-
stood. The pipe w is lined with segmental fire-bricks w* in order to
defend the outer iron shell from the effects of heat, and also to prevent
loss of pressure in the gases and vapours by the radiation of heat there-
from. A force pump worked by the blast engine forces water to the
top of the pipe w by a pipe which passes through the top of the pipe w
at x, having a rose head v perforated in such a way as to cause water
forced through it to fall in a shower down the pipe w, for the purpose of

page_text: lowering the temperature of the furnace gases to a point suitable for the
hot air engine to be driven by them; and although I prefer a direct-
acting blast engine, as before named, it will nevertheless be obvious that
any efficient plan of blast engine may be used, the ordinary steam
cylinder of which will be supplied with waste gases mixed with the steam
generated by them from the falling shower of water, such cylinder being
in all cases of sufficient diameter to compress the blast to the desired
extent. The volume of steam and gases always being in excess of the
volume of air and water injected by reason of the expansion of the air
by the heat of the furnace and the formation of steam from the falling
shower, of water.
And although I have described the working of the blast furnace under
the pressure of confined gases,. I desire it to be understood that certain
parts of my said improvements are equally applicable to blast furnaces
working with open tops and furnaces where the waste gases are collected
for combustion in hot air stoves or under boilers. These improvements
consist in the mode shown and described of allowing an outflow of
a portion of the carbonic acid gas at a short distance from the
tuyeres, and also the continuous flow of metal and cinder from the
furnace.
Having described my Invention, and the way in which it may be
carried into practical operation, I desire it to be understood that I do not
confine myself to the precise details here given, provided that the
peculiar character of my Invention be retained; but I claim as my
improvements in the construction and mode of working blast furnaces
employed for smelting the ores of iron and in the mode of employing and
utilizing the gaseous products of such furnaces, and also in the con-
struction and mode of working blast engines employed to force air into
blast and other furnaces,-
First. The entirely enveloping the masonry or brickwork of a blast
furnace in a strong air-tight case or jacket to admit of the gaseous pro-
ducts of combustion being retained under considerable pressure.
Second. The enclosing the bosles of blast furnaces so as to have the
tuyere holes opening externally into a large chamber accessible to
workmen and containing air under pressure.
Third. The enclosing the tymp and tap hole of blast furnaces in a
large chamber capable of containing air under pressure, so that the

page_text: pressure of air therein may, when required, prevent escape of flame at
the tymp and tap hole.
Fourth. The providing outlets from a blast furnace near the tuyeres
for the escape of a portion of the gases in the state of carbonic acid.
Fifth. The so arranging and operating when a carburizing vessel is
used that the metal may run continuously from the blast furnace into
the carburizing vessel.
Sixth. The smelting ores of iron in blast furnaces in which the gascous
products of combustion are retained throughout the furnace under a
pressure considerably exceeding that of the external atmosphere.
Seventh. The combining an air engine and air pumps with a high-
pressure blast furnace in such manner that the gases issuing from such
furnace are caused to pass through and work such engine, and thereby
actuate the pumps which supply the blast to the furnace.
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.
HENRY BESSEMER. (L.S.)