IMPROVE- MENTS IN THE MANUFACTURE OF STEEL, AND IN FURNACES AND APPARATUS TURDREAD ATCO BIRTLY ADDED TO ATHLED ܘܕPinnoc SP
Year: 1881

page_text: LETTERS PATENT to Charles William Siemens, of No. 12, Queen Anne's Gate,
Westminster, in the County of Middlesex, for an Invention of "IMPROVE-
MENTS IN THE MANUFACTURE OF STEEL, AND IN FURNACES AND APPARATUS
TURDREAD ATCO BIRTLY ADDED TO ATHLED
ܘܕPinnoc
PROVISIONAL SPECIFICATION left by the said Charles William Siemens
at the Office of the Commissioners of Patents on the 31st August 1881.
CHARLES WILLIAM SIEMENS, of No. 12, Queen Anne's Gate, Westminster, in
the County of Middlesex. "IMPROVEMENTS IN THE MANUFACTURE OF STEEL,
AND IN FURNACES AND APPARATUS THEREFOR, ALSO PARTLY APPLICABLE TO
OTHER PURPOSES."
In the manufacture of steel by the open-hearth process, according to the method
hitherto practised, raw cast iron and scrap metal are charged in a regenerative
gas furnace, and the resulting metal is farther decarburised by the addition of
scrap or of iron oxides, after which an alloy of iron carbon and manganese is added
to the charge in the furnace or when it is run into a ladle, as set forth in the
Specifications of Patents previously granted to me; the metal is then discharged
into moulds for the production of steel ingots or castings.
According to my present Invention I employ an open hearth regenerative
gas furnace, but in order to prevent or lessen the destructive action of scoria upon
the sides of the bed of the melting chamber I add thereto pipes for circulating
water around the bed.
The furnace being heated and the bed or bottom being prepared in the usual
manner, I place thereon a charge of iron oxide, which may be a mixture of small
ore and roll scale spread uniformly over the bed, followed by or mixed with scrap
metal or puddled blooms. The furnace doors are then closed and these materials
are raised as rapidly as possible to a white heat. Fluid cast iron is then poured in,
which may be taken direct from a blast furnace, or from a cupola or other melting
furnace, but when a high class product is required I prefer to take the fluid cast
IP 671

page_text: iron from a special furnace constructed and worked as hereafter described. The
cast iron in uniting with the materials previously in the furnace becomes partially
decarburised; in order farther to decarburise the metal under treatment, ore with
or without addition of scrap and blooms should be added gradually in the manner
now practised, and when the metal has attained the desired point of conversion
(which may be ascertained by taking samples from time to time) in certain cases
spiegeleisen or other alloy of metals may be added in the usual manner. The
contents of the furnace are then tapped into a ladle, and as they run a small
percentage of rich ferro-manganese, previously heated to redness and broken to the
size of walnuts or hazelnuts, may be thrown into the liquid stream. From the
ladle the fluid steel is discharged into moulds for the production of ingots or
castings.
The furnace above referred to which I prefer to employ for melting and purifying
the cast iron for making steel has a bed or floor steeply inclined and terminating
in a basin provided with a tapping hole. This bed should be of a basic character,
and either consist of or be provided with a lining or covering of a material such as
pure magnesia, or lime with magnesia or alumina, or of bauxite or other strongly
aluminous clays. The flame ports are at the basin or lower end of the bed, the
passages to the chimney being at the higher end. The crown of the furnace
consists of a double arch, the space between the two arches forming a passage for
the air destined to maintain the combustion. This air in its passage through
conduits interposed in the chimney flue and through the channel in the furnace
crown becomes highly heated, and in this condition meets at the flame ports gas
supplied from a producer adjoining or near to the furnace structure, and which
may be of the construction hereinafter described. In order to prevent the air on
its passage through the said space formed by the double arch froin leaking into the
furnace chamber, the lower arch may be coated on one or both sides with a wash
or thin layer of lime, soda, or other alkaline substance, which on becoming heated
will flux with the bricks and cement of the joints, thus forming on the surface of
the arch an enamel or glaze which is impermeable or nearly so to the passage of
gases, or silicates may be used for this purpose. This method of producing an
impermeable glaze on the surface of brickwork may be employed in regenerative
furnaces generally for those parts which serve to effect the transmission of heat by
conduction from currents circulating on one side of brick partitions, to currents
passing along the other side thereof, as for instance in the regenerators operating
as described in Letters Patent granted to me bearing date the 19th August 1880,
and numbered 3374.
The inclined bed of the furnace above referred to being covered with iron oxide
on which the cast iron is charged, this metal in melting and flowing down to the
basin combines with or is reacted on by the iron oxide and basic materials on the
bed, finally presenting on the top of the molten metal in the basin a basic slag
containing a large proportion of the silicon, phosphorus, and sulphur originally
contained in the cast iron. The basic character of this slag may be farther
promoted by the addition of lime, manganese, or other suitable substances, so as to
prevent the re-incorporation of the impurities with the cast iron under treatment.
One melting and purifying furnace of the kind described may be conveniently
placed opposite a row of four open-hearth steel melting furnaces, and at such an
elevation that the metal will run through a removeable spout directly to one or
other of the steel melting furnaces which may be ready to receive a charge. This
method of working effects a saving of time and labour in the manufacture of steel
on the open hearth, the fluid cast iron coming in contact with scrap and blooms
and oxides in a highly heated condition, readily combining therewith and forming
at once a liquid bath decarburised to a considerable extent.
In carrying out the above described method of steel manufacture, blooms made
direct from iron oxide in rotative furnaces, as described in my previous Patents,
may be used with advantage, inasmuch as they may be charged hot into the steel
melting furnace. These balls (or blooms if shingled) however should be of a convenient

page_text: size for handling, and partly with a view of attaining this object I described in
the Specification of my Patent, No. 5150, of 1879, means of forming inside of
rotative furnaces projections and ridges cooled by water circulation, whereby the
mass of metal under treatment was divided into several separate portions or blooms.
For this purpose bent pipes were carried through the interior of the drum pro-
ducing the ridges and projections, and made to communicate at one end of the
rotator with a water casing and at the other with a trunnion joint at the centre
of the front of the vessel, provided with a facing like that of a rotating slide valve,
the ports communicating with the said pipes, and also with supply and discharge
pipes, of which the former leads from a cistern, pump, or accumulator, while the
latter leads to a drain so as to effect a continuous circulation of water through
them.
According to my present Invention, instead of carrying the whole of the pipes
through the inside of the rotator as there described, I place the pipes outside the
drum and only cause the bends for forming the internal projections to pass into
the interior through apertures made for that purpose in the cylindrical casing. Or
I form inwardly projecting pockets or hollow internal projections on the casing
into which the external pipes enter, there being one pipe for delivering the water
into the pocket or projection, and another by which it passes out again, so that a
continual circulation of water is maintained through the pockets; or the water may
be supplied through branch pipes as a jet impinging against the inner surface of
each pocket and be allowed to flow off again rapidly. Or, according to another
modification, I surround the rotator with a double casing or jacket, from which
pipes lead to the trunnion joint, the before mentioned pockets being open to the
double casing at their outer ends, and the water supply pipes may be led through
the interior of the double casing or along its outer or inner surface, and may be
provided with branches projecting into the pockets, the water supply being either
such that the pockets are always kept filled with water or that jets of water are
made to impinge upon them, as above described. Owing to the coolness of the
above mentioned pockets, a portion of the molten material solidifies on them,
encrusting them so as to form mounds projecting from the general surface of the
lining, for the purpose of dividing the mass under treatment into separate lumps
or blooms.
The gas producer which I prefer to employ in combination with the above
described furnaces is of the kind described in the Specification to my Patent, dated
19th August 1880, No, 3374, but instead of the central tube or passage for
delivering the air into the mass of incandescent fuel, I according to my present
Invention cause the air to enter through two or more nozzles projecting laterally
through the sloping lower part of the gas producer, the nozzles being by preference
inclined in such a direction that the jets of air issuing from them will all be
propelled towards the centre of the mass of fuel, so as to produce the more intense
combustion at that point. The nozzles are supplied from branch air pipes leading
up inside the producer, and connected to coils or zig-zag pipes communicating with
the main air supply pipe and arranged in or near the passages or flues through
which the hot.combustible gases pass away, so that the air on its passage to the
nozzles from the main air pipe through these coils becomes heated to a considerable
degree. Or the said air supply pipes may be led to the nozzles outside the
producer, so as to supply the air without being previously heated.
According to another modification, I dispense with the forced air supply to the
circular form of producers above referred to, and I construct the lower part of the
sloping or conical bottom of the producer as an open grate, through which the
requisite in-draught of air is admitted. The grate may with advantage formed
of bars hooked with their bent upper ends on to a circular support, and sloping down-
wards. In this arrangement, as also in that where the sloping bottom is entirely
solid, stoppered inclined holes are forined at the top of such sloping part, through
which a stirring bar may be introduced from time to time for breaking up and
removing clinkers and ashes. The part of the sloping bottom formed as a grate

page_text: may be enclosed by a circular moveable screen or curtain, stopping short of the
bottom so as to leave sufficient space below for the admission of air to the grate.
Water may be admitted to the bottom of the gas producer by means of a circular
perforated pipe, which water in dropping on the red hot cinders serves the double
purpose of cooling these and of supplying the gas producer with aqueous vapour to
effect the decomposition of the incandescent carbonaceous matter within the gas
producer, forming carbonic oxide and hydrogen gases.
It will be evident that the above described improved constructions of gas
producers are applicable to the production of combustible gases for heating purposes
generally.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles William Siemens in the Great Seal Patent Office on the
28th February 1882.
CHARLES WILLIAM SIEMENS, of No. 12, Queen Anne's Gate, Westminster, in
the County of Middlesex. "IMPROVEMENTS IN THE MANUFACTURE OF STEEL
AND IN FURNACES AND APPARATUS THEREFOR, ALSO PARTLY APPLICABLE TO
OTHER PURPOSES."
In the manufacture of steel by the open-hearth process, according to the method
hitherto practised, raw cast iron and scrap metal-are-charged-in.a.regenerative gas
furnace, and the resulting metal is farther decarburised by addition of scrap or of
iron oxides, after which an alloy of iron carbon and manganese is added to the charge
in the furnace or when it is run into a ladle, as set forth in the Specifications of
Patents previously granted to me; the metal is then discharged into moulds for
the production of steel ingots or castings.
According to my present Invention I employ an open hearth regenerative gas
furnace, but in order to prevent or lessen the destructive action of scoria upon the
sides of the bed or lining of the melting chamber, I add thereto pipes for circulating
water around and cooling the upper part of the bed without cooling the furnace in
other parts.
Fig. 1 of the accompanying Drawings is a longitudinal section on X, X; Fig. 2
is a transverse section on Y, Y, and Fig. 3 is a plan on Z, Z, of a furnace thus
arranged. A is the bed, B are working doors, and C is the tapping hole.
At one
end of the furnace there are gas flues G and air flues D, which rise to a shallow
space E above the mouths of the gas flues, so that the hot air becomes spread out
into a broad stream over the gas entering by the mouths of G, and the flame is
deflected by the crown on to the material upon the bed. At the other end of the
furnace there are corresponding flues G' and D'. For a time the flues D', G¹, serve
to convey the hot products of combustion to one pair of regenerative chambers,
which are conveniently situated below the furnace, while the gas and air issuing
from the flues G, D, at the other end are heated in passing through the other pair

page_text: of regenerative chambers. When one of the pairs of chambers has become heated
and the other pair cooled to a certain degree the direction of the currents is reversed,
that is to say, the gas and air are admitted by the flues G¹ and D', and the products
of combustion pass away by the flues G and D, and so on alternately, in the well
known manner of working regenerative gas furnaces. F are the water pipos abovo
referred to, which may be placed in recesses of the structure behind the sloping
sides and ends of the bed. These pipes are kept supplied with water admitted to
them at H in quantity regulated by suitable stop cocks or valves, and discharged
from them by the descending branches J. It is of advantage to keep all joints
outside the furnace, and to provide for expansion and contraction of the pipes. For
this purpose the junctions K are formed each like an inverted U, on which a cock
for discharge of air or vapour may be provided at the top of the bend.
The furnace being heated, and the bed or bottom being prepared in the usual
manner, I place thereon a charge of iron oxide, which may be a mixture of small
ore and roll scale spread uniformly over the bed, followed by or mixed with scrap
metal or puddled balls and blooms. The furnace doors are then closed, and these
materials are raised as rapidly as possible to a white heat. Fluid cast iron is then
poured in, which may be taken direct from a blast furnace or from a cupola or other
melting furnace; but when a high class product is required, I prefer to take the
fluid cast iron from a special furnace constructed and worked as hereafter described.
The cast iron in uniting with the materials previously in the furnace becomes
partially decarburised. In order farther to decarburise the metal under treatment,
ore, with or without addition of scrap and balls or blooms, should be added
gradually in the manner now practised, and when the .metal has attained the
desired point of conversion (which may be ascertained by taking samples from
time to time), in certain cases spiegeleisen or other alloy of metals may be added
in the usual manner. The contents of the furnace are then tapped into a ladle,
and as they run a small percentage of rich ferro-manganese, previously heated to
redness and broken to the size of walnuts or hazelnuts, may be thrown into the
liquid stream instead of into the ladle, as heretofore, a more intimate mixture being
thus secured. From the ladle the fluid steel is discharged into moulds for the
production of ingots or castings.
The furnace above referred to, which I prefer to employ for melting and
purifying the cast iron for making steel, is of the kind shewn in conjunction with
a gas producer by Fig. 4, which is a longitudinal section, and Fig. 5, which is a
sectional plan on X, X. The bed or floor A is steeply inclined and terminates in a
basin B, provided with a tapping hole C. The bed should be of a basic character,
consisting of or being provided with a lining or covering of a material such as pure
magnesia, or lime with magnesia, or alumina, or of bauxite, or strongly aluminous
clays, or certain iron ores; D are the flame ports at the basin or lower end of the
bed, and E is the chimney at the higher end. The crown of the furnace consists
of a double arch with a space F between them, forming a passage for the air
destined to maintain the coinbustion and furnished with bafflers f, which may be
formed of tie bricks uniting and strengthening the two arches. This air in its
passage through conduits G in the chimney flue, and through the channel F
becomes highly heated, and in this condition meets at the flame ports D gas
supplied from a producer adjoining or near to the furnace, this producer being of
the kind shewn in Figs. 4 and 5, or of the modified forms hereinafter described. In
some cases, instead of relying only on the chimney for drawing in air to the furnace
steam jets or a blast of air may be used, which jet or blast may be introduced at
the extremity of the conduits G or at any other part of the air course, as may be
found desirable. In order to prevent the air on its passage through the said space
formed by the double arch from leaking into the furnace chamber, the lower arch
may be coated on one or both sides with a wash or thin layer of lime, soda, or
other alkaline substance, which on becoming heated will flux with the bricks and
cement of the joints, thus forming on the surface of the arch an enamel or glaze,
which is impermeable or nearly. so to the passage of. gases; or basic silicates may

page_text: be used for imparting such a glaze to the brickwork. This method of producing
an impermeable glaze on the surface of brick work may be employed in regenerative
furnaces generally for those parts which serve to effect the transmission of heat by
conduction from currents circulating on one side of brick partitions to currents
passing along the other side thereof, as, for instance, in the regenerators operating
as described in the Specification to Letters Patent granted to me bearing date the
19th August 1880, and numbered 3374. Thin brick partitions thus glazed may be
employed in such regenerators in lieu of metal plate partitions described in the
said Specification, and tie bricks forming bafflers may also be added therein as
already described with reference to double arches of furnaces.
The inclined bed of the furnace above referred to being covered with iron oxide
on which the cast iron is charged, this metal in melting and flowing down to the
basin combines with or is reacted on by the iron oxide and basic materials on the
bed, finally presenting on the top of the molten metal in the basin a basic slag
containing a large proportion of the silicon, phosphorus, and sulphur originally
contained in the cast iron. The basic character of this slag may be farther pro-
moted by the addition of lime, manganese, or other suitable substances, and the
fluid slag may be removed, so as to prevent the re-incorporation of the impurities
with the cast iron under treatment. A furnace, such as I have described, besides
being employed for melting the cast iron to be used in steel manufacture, may be
used with great advantage as a foundry furnace for making castings of great
strength and purity and for other like purposes.
One melting and purifying furnace of the kind described may be conveniently
placed opposite a row of four open-hearth steel melting furnaces, and at such an
elevation that the metal will run through a removeable spout directly to one or
other of the steel melting furnaces which may be ready to receive a charge. This
method of working effects a saving of time and labour in the manufacture of steel
on the open hearth, the fluid cast iron coming in contact with scrap, and blooms,
and oxides in a highly heated condition, readily combining therewith and forming
at once a liquid bath decarburised to a considerable extent.
In carrying out the above described method of steel manufacture, balls or blooms
made direct from iron oxide in rotative furnaces, as described in the Specifications of
my previous Patents, may be used with advantage, inasmuch as they may be charged
hot into the steel melting furnace. These balls or blooms however should be of a
convenient size for handling, and partly with a view of attaining this object I
described in the Specification-of-my-Patent, No.5150-of-1879, means of forming
inside of rotative furnaces projections and ridges cooled by water circulation,
whereby the mass of metal under treatment was divided into several separate
portions or blooms. For this purpose bent pipes were carried through the interior
of the drum producing the ridges and projections, and made to communicate at one
end of the rotator with a water casing, and at the other end with a trunnion joint
at the centre of the front of the vessel, provided with a facing like that of a
rotating slide valve, the ports communicating with the said pipes and also with
supply and discharge pipes, of which the former leads from a cistern, pump, or
accumulator, while the latter leads to a drain, so as to effect a continuous circulation
of water through them.
According to my present Invention, instead of carrying the whole of the pipes
through the inside of the rotator, as there described, I place the pipes outside the
drum, and only cause the bends for forming the internal projections to pass into
the interior through apertures made for that purpose in the cylindrical casing.
This construction is shown in Fig. 6, which is a longitudinal section, and Fig. 7,
which is a transverse section of the rotator drum. The water pipes H are fixed
outside the casing of the drum, with only their bent parts h projecting inwards
through apertures made in the cylindrical casing. All the pipes of the rotator may
be thus arranged, or some of them may be thus arranged, others of them being led
through the drum from end to end within the casing, as shewn at I in Fig. 6.
According to a modified arrangement, shewn by the part longitudinal and transverse

page_text: sections, Figs. 8 and 9, I form inwardly projecting pockets or hollow internal
projections K on the casing into which the pipes enter, there being one pipe / for
delivering the water into the pocket, and another by which it passes out again,
so that a continual circulation of water is maintained through the pockets. The
water might be supplied by branch pipes as jets impinging against the interiors of
the pockets and allowed to flow rapidly away. In these rotating furnaces the
cooling pipes may be connected at the throat end of the furnace either by a water
casing with which they communicate, or by branch pipes carried either directly
across the end of the drum or bent in several convolutions around the throat.
According to another modification, shewn by the longitudinal section, Fig. 10,
I surround the rotator with a double casing or jacket L, which communicates with
the trunnion joint M. The pockets K are open to the space L, and the water
supply pipes have branches projecting into the pockets. These pipes may be, as
shewn in Fig. 10, arranged outside the external shell, or they might be led along.
the space
L between the two shells, or within the inner shell. The supply and
discharge of the water may be so regulated that the pockets K. and the jacket L
are kept filled, or that the water may be made to impinge in jets upon the internal
surfaces of the pockets. Owing to the coolness of the above mentioned pockets
and pipes, a portion of the molten material solidifies on them, encrusting them so
as to form mounds and ridges projecting from the general surface of the lining, for
the purpose of agitating the mass under treatment and dividing it into separate
lumps or blooms.
The gas producer which I prefer to employ in combination with the above
mentioned furnace is of the kind described in the Specification of a Patent granted
to me, dated 19th August 1880, No. 3374, but instead of the central tube or
passage for delivering air into the mass of incandescent fuel, I, according to my
present Invention, cause it to enter through two or more nozzles. In Figs. 4 and 5.
this arrangement of gas producer is shewn; the air supply pipes O project through
the lower sloping part at several points and direct the air currents obliquely
upwards towards the heart of the fuel in the producer. In order to heat the air
thus supplied and cool the gas produced the air pipes are bent into coils or
zig-zags o, which lie in the annular space P where the gases produced collect on
the way to the furnace; at one extremity the air pipes O communicate with a
main pipe O¹ charged with air under pressure.
According to another modification, shewn in vertical section by Fig. 11, the
forced air supply to the circular form of gas producer is dispensed with, and I
construct the lower part of the sloping or conical bottom as an open grate, the
requisite air being admitted between the bent bars N, which may be supported by
rings n, n, as shewn, or they may with advantage be formed of bars hooked with
their bent upper ends on to a circular support and sloping downwards, as shewn in
Fig. 12. The sloping bars are formed as a grate, and may be enclosed by a circular
moveable screen provided with doors u that can be opened and shut so as to admit
more or less air to the gas producer. In this form of gas producer a.central air
or steam jet, as described in the Specification to my Patent, No. 3374 of 1880,
above referred to, may be employed, as shewn by the vertical section, Fig. 12.
The air in this case is supplied at the bottom of the gas producer, having been
previously heated by passing through a casing Q at the top, separated by a metal
plate g from the space P in which the gases collect. In order to increase the heating
effect on the air the plate q is made with pockets q' projecting down into the gas
space P. The air descends from the casing Q by pipes O leading to channels R
under the floor of the gas producer and thence to a central space R', whence it rises
through the nozzle S into the body of the fuel if it be under pressure, or a current
may be created by a steam jet T, which also supplies a quantity of aqueous vapour,
to act with the air upon the fuel. Instead of a partition of bricks separating the
incoming fuel from the gases produced, a metal partition PI may be employed,
as shewn in Fig. 11. Water may be admitted to the bottom of these gas producers
by means of a circular perforated pipe, as shewn in Fig. 12 (or otherwise), which

page_text: water dropping as streams on the bent bars N, and the hot cinders serves the
double purpose of cooling them and of supplying the gas producer with aqueous
yapour to assist in effecting the decomposition of the incandescent carbonaceous
matter within the gas producer. Stoking holes vare shown as provided at top and
sides of these gas producers, through which bars may be introduced from time to
time for breaking up the fuel and removing clinkers and ashes.
Instead of supplying heated air to these gas producers, as shown and described,
the incoming air, whether under pressure or an induced current, may be led to the
supply nozzles or jets without being previously heated.
The above described constructions of gas producers are obviously applicable to
the production of combustible gas for heating purposes generally, and for gas
motors, such, for example, as those of the kind described in the Specification to a
Patent granted to me, and dated. the 9th June 1881, No. 2504; also instead of
being circular in plan these gas producers may be made approximately circular or
polygonal, or of other forms, and in such cases the use of two or more jets may be
found advantageous.
Having thus described the nature of my Invention and in what manner the
same is to be performed, I claim,-
First. In the manufacture of steel, heating in an open hearth furnace iron oxide
with scrap metal and puddled ball, and pouring thereon fluid cast iron so as to
form a mixture for subsequent treatment in the ordinary way for the production
of steel, substantially as herein described.
Second. Adding to the liquid stream of steel metal as it runs from the furnace
heated, ferromanganese in small pieces, as herein described.
Third. The construction of furnace for steel manufacture with cooling water
pipes, arranged substantially as herein described with reference to Figs. 1, 2,
and 3.
Fourth. The construction of furnace, substantially as herein described with
reference to Figs. 4 and 5.
Fifth. The method herein described of rendering impermeable by a glaze the
fire brick partitions employed to separate a heating current from the current
heated by it.
Sixth. The arrangement herein described with reference to Figs. 6 and 7 of
water pipes with bends projecting inwards through the casing of a rotative
furnace.
Seventh. The use in a rotative furnace of inwardly-projecting-pockets.cooled
by circulation or jets of water, substantially as described with reference to Figs. S,
9, and 10.
Eighth. The construction of gas producer, substantially as herein described with
reference to Figs. 4 and 5.
Ninth. The modified construction of gas producer, substantially as described
with reference to Figs. 11 and 12.
In witness whereof, I, the said Charles William Siemens, have hereunto set
my hand and seal, this Twenty seventh day of February, in the year of
our Lord One thousand eight hundred and eighty two.