IMPROVEMENTS IN FURNACES, AND IN PROCESSES AND APPARATUS IN CONNEC- CONTION THEREWITH, PRINCIPALLY APPLICABLE TO METALLURGICAL OPERATIONS
Year: 1867

page_text: LETTERS PATENT to Charles William Siemens, of No. 3, Great George
Street, Westminster, in the County of Middlesex, for the Invention of
"IMPROVEMENTS IN FURNACES, AND IN PROCESSES AND APPARATUS IN CONNEC-
PROVISIONAL SPECIFICATION left by the said Charles William Siemens
at the Office of the Commissioners of Patents, with his Petition, on the
21st August 1867.
I, CHARLES WILLIAM SIEMENS, of No. 3, Great George Street, Westminster,
in the County of Middlesex, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN FURNACES, AND IN PROCESSES AND APPARATUS
IN CONNECTION THEREWITH, PRINCIPALLY APPLICABLE TO METALLURGICAL
OPERATIONS," to be as follows:-
My improvements have reference principally to the application of furnaces
in which gaseous fuel and regenerators are used to the production of cast steel.
Cast steel may be produced directly from the ore by the process described
in the Specification to certain Letters Patent granted to me, and bearing date
the 20th September 1866, No. 2413, or it may be produced by melting cast
iron (containing by preference manganese) and scrap iron, or scrap steel, or
blooms of puddled steel or iron, in a reverberatory furnace; or it may be
produced by these two processes conjointly.

page_text: In the Specification to the before-mentioned Letters Patent two general
arrangements of furnaces were shown, in one of which the ore with its
admixtures of fluxes and reducing agents descended at the two sides of the
heated chamber, and in the other of which the ore descended through a single
shaft or hopper upon the bed of a reverberatory furnace.
According to my present Invention these shafts or hoppers are placed
vertically, or nearly so, and are made of considerable altitude in order to
cause a more gradual and uniform descent of the ore into the furnace, and
the reduction of the ore within these shafts or hoppers is further activated by
the application of flues or heated chambers round about them, through which
the heat of the furnace is made to circulate. Into each vertical ore shaft a
pipe carrying a supply of hydrocarbon or other reducing gases may be made
to enter, either from above or from below, with its outlet near the base of the
vertical column. I prefer to heat this gas previously, either by drawing it
from the upper ends of the gas regenerators of the furnace, or by special heating
apparatus. If the supply of heated reducing gases is taken from the regene-
rators of the furnace I introduce the same through an ascending channel
under a hood at the foot of the column of ore, which ascending channel
divides underneath the bed of the furnace or heated chamber into two
channels leading to the two gas regenerators, one of which has to be
closed by a fire-brick valve or other means. The hood or slab covering the
vertical gas channel may be suspended by a rod reaching down through the
column of ore for the purpose of regulating the supply of gas and of moving
the mass of ore in raising and lowering the same by means of a lever or other
mechanism. The same suspending rod may be made to serve the purpose of
opening and closing the gas channels leading to the regenerators by imparting
a rotary motion to the same. The, rod, hood, and gas reversing valve may in
this case be made of wrought iron or steel, being secured against oxydation
by the gas.
If the ore employed is in the state of powder, and therefore not
pervious to the reducing gases, I mix the same with loose and pervious
reducing agents, such as wood in small pieces, dried peat and charcoal, instead
of pitch, asphalt, or oils, as mentioned chiefly in the Specification to. the
before-mentioned Letters Patent, or both classes of substances combined,
in which case the introduction of gas may be dispensed with.
In using
such solid carbonaceous matter in connection with the ore the metal pro-
duced frequently contains a larger proportion of, carbon than is requisite
for, the formation of steel. The metallic bath may in that case be deprived of
its excessive carbon by throwing, oxides of iron or iron ore upon its surface
and agitating the mass, or wrought iron may be added in the form of puddled

page_text: blooms or of scrap.
For the introduction of such scrap or puddled bloom a
separate door or doors are provided, whence- an inclined plane descends
towards the bath, the object being to heat the iron to a full white heat upon
the inclined plane before it is pushed forward into the bath, wherein it readily
dissolves; or wrought or cast metal may be fed down with the ore in a more
or less divided state. If no ore is employed then the vertical hoppers or
shafts may be dispensed with, and doors only provided at the upper part of the
inclined planes above referred to. At the end of each operation, before
tapping the metal I generally add a certain proportion of rich spiegel eisen
or metallic manganese to the bath in order to improve the quality of the steel.
The ore to be employed for the process should by preference be a pure
oxide of iron, containing as little gang, or sulphur, or phosphorus as possible.
Magnetic ironstone or hematite ore are particularly applicable. If spathic
ores are used I prefer to calcine them beforehand, and also the lime or other
flux which has to be used when the ore contains any considerable admixture
of silica.
gaseous
The kiln I employ for calcining these materials is not dissimilar general
form and arrangements to an ordinary lime kiln; but the material to be
calcined is charged. at the top without admixture of solid fuel. Gaseous
fuel is admitted at the circumference of the kiln at some elevation from the
base, and also in the centre of the kiln through an ascending channel and
under a covering hood. Atmospheric air enters among the calcined and
heated mass through the discharge openings at the bottom of the kiln, and
after having become heated itself meets with the divided currents of
fuel, with which it enters into complete combustion, producing intense heat.
The products of combustion, together with the liberated carbonic acid and
aqueous vapour rising through the superincumbent mass of material, heats
the same preparatory to the calcining heat, escaping at the top comparatively
cool from the freshly charged materials. One advantage of this calcining
kiln is that the products of combustion escape from it in the form of carbonic
acid instead of carbonic oxide, with their admixture of nitrogen, resulting in a
great.saving of fuel; another advantage consists in the absence of ashes with
the combustible matter employed; and another in the regular and intensified
action which can be obtained in regulating the supply of gas to the continuous
action of the kiln. A gallery or galleries are erected on the outside of the
kiln, and stoppered apertures are provided through its side walls for the
purpose of introducing tools for prising the material in case it should hold
together and not descend freely. The current of air and gas through the
calcining mass may be accelerated by placing a hood or chimney upon the

page_text: kiln, and by introducing a steam jet into the same. Kilns of this description
may be used generally with advantage in calcining ores and for burning lime,
cement, and plaster of Paris.
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 21st February 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
WILLIAM SIEMENS, of No. 3, Great George Street, Westminster, in the
County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-first day of August, in the year of our Lord
One thousand eight hundred and sixty-seven, in the thirty-first year of Her reign,
did, for Herself, fer heirs and successors, give and grant unto me, the said
Charles William Siemens, Her special licence that I, the said Charles William
Siemens, my executors, administrators, and assigns, or such others as I, the
said Charles William Siemens, 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 FURNACES, AND IN PROCESSES AND APPARATUS IN CONNECTION THEREWITH, PRINCI-
PALLY APPLICABLE TO METALLURGICAL OPERATIONS," upon the condition (amongst
others) that I, the said Charles William Siemens, my executors or administrators;
by an instrument in writing under my, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said Invention,
and in what manner the same was to be performed, and cause the same to be
filed in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I; the said Charles William Siemens, 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, reference being had to the accompanying Drawings, and to
the figures and letters marked thereon; that is to say :-
My improvements, have reference principally to the application of furnaces.
in which gaseous fuel and regenerators are used to the production of cast
steel.

page_text: Cast steel may be produced directly from the ore by the process described
in the Specification to certain Letters Patent granted to me, and bearing date
the 20th September 1866, No. 2413, or it may be produced by melting cast
iron (containing by preference manganese) and scrap iron, or scrap steel, or
blooms of puddled steel or iron in a reverberatory furnace, or it may be
produced by these two processes conjointly.
In the Specification to the before-mentioned Letters Patent two general
arrangements of furnaces were shown, in one of which the ore with its
admixtures of fluxes and reducing agents descended at the two sides of the
beated chamber, and in the other of which the ore descended through a single '
shaft or hopper upon the bed of a reverberatory furnace.
According to my present Invention these shafts or hoppers are placed
vertically, or nearly so, and are made of considerable altitude, descending at
the same time to the surface of the metallic bath in the furnace, or nearly so,
in order to cause a more gradual and uniform descent of the ore into the
furnace with as little exposure as possible of the spongy metal reduced in the
hoppers to the oxydizing influence of the flame, and the reduction of the ore
within these shafts or hoppers is further actuated by the application of flues
or heated chambers round about them through which the heat of the furnace
is made to circulate; these shafts may be in the form of pipes, tubes, or
retorts descending into the aforesaid heated chambers throngh the roof of the
furnace. Into each vertical ore shaft a pipe carrying a supply of hydrocarbon
or other reducing gases may be made to enter from above with its outlet near
the base of the vertical column. If the ore employed is in the state of powder,
and therefore not pervious to the reducing gas' I mix the same with loose and
pervious reducing agents, such as wood in small pieces, sawdust, dried peat,.
and charcoal, separately or in conjunction with pitch, asphalt, or oils, as
mentioned chiefly in the Specification to the before-mentioned Letters Patent,
in which case the introduction of gas may be dispensed with.
In commencing operations I generally form a metallic bath of cast iron.
introduced through side doors of the furnace, which greatly facilitates the
liquifaction of the metallic spongy iron formed in the hoppers. With the ore
scrap iron or steel, such as engineers' turnings, &c., or cast iron in a more or
less divided state, may be charged into the hoppers to be also absorbed in the
metallic bath, or wrought metal may be fed in through separate side doors or
hoppers. If only wrought and cast metal are to be employed then in place
of the vertical hoppers or shafts inclined hoppers may be conveniently adopted,
through which the wrought iron, such as bars or old rails, descend by gravity,
dipping with their most heated ends into the metallic bath, where they are

page_text: dissolved, a certain portion of flame being allowed to escape out of the top of
the hopper in order to warm the iron during its descent and without lowering
the temperature of the furnace; or pigs of cast metal, by preference white
metal, may be fed down these hoppers, and an oxidizing flame be resorted to
for effecting the necessary decarbonization, the oxygen supplied to the regene-
rative gas furnace to be employed being at a very elevated temperature, and
therefore well adapted for effecting such decarbonization, which moreover
may be aided by stirring and by the addition of comparatively pure metallic
oxides on the surface of the bath. At the end of each operation, whatever
may be the ingredients employed, before tapping the metal. I generally add a
certain proportion of rich spiegel eisen or metallic manganese to the bath in
order to improve the quality of the steel. The ore to be employed for the
first-named process should by preference be a pure oxide of iron containing
as little gang, or sulphur, or phosphorus as possible. Magnetic ironstone,"
hematite ore, and rich calcined spathic ore are particularly applicable, or such
a mixture may be conveniently adopted as contains both silica and fluxing
material, such as lime or magnesia in suitable proportions, avoiding the
necessity of adding separate fluxing material.
The kiln I employ for calcining the spathic ore or lime to be used is not
dissimilar in general form and arrangement to an ordinary lime kiln, but the
material to be calcined is charged at the top without admixture of solid fuel:
Gaseous fuel is admitted at the circumference of the kiln at some elevation
from the base, and also in the centre of the kiln through an ascending channel'
and under a covering hood. Atmospheric air enters among the calcined and
Heated mass through the discharge openings at the bottom of the kiln, and
after having become heated itself meets with the divided currents of gaseous
fuel, with which it enters into complete combustion, producing intense heat.
The products of combustion together with the liberated carbonic acid and
aqueous vapour rising through the superincumbent mass of material heats the
same preparatory to its being acted upon by the calcining heat, and escapes at
the top comparatively cool from the freshly charged materials. One advantage
of this calcining kiln is that the products. of combustion escape from it in
the form of carbonic acid instead of carbonic oxide with their admixture of
nitrogen, resulting in a great saving of fuel ;' another advantage consists' in the
absence of ashes in the combustible matter employed; and another in the
regular and intensified action which can be obtained in regulating the supply
of gas to the continuous action of the kiln. A gallery or galleries are erected
on the outside of the kiln, and stoppered apertures are provided through its
side walls for the purpose of introducing tools for prising the material. in

page_text: case it should hold together and not descend freely. The current of air and
gas through the calcining mass may be accelerated. by placing a hood or
chimney upon the kiln, and by introducing a steam jet into the same. Kilns⚫
of this description may be used generally with advantage in calcining ores and
for burning lime, cement, and plaster of Paris.
Having thus set forth the nature of my Invention I will now proceed more
particularly to describe the arrangements of furnaces which I prefer to employ
in carrying the same into effect.
Figures 1 to 19 on Sheets I. and II. of the accompanying Drawings shew
the before-described two principal types of furnaces for the production of cast
steel in large masses, one of which is arranged more particularly for the
employment of oxides or other iron ores, and the other for the conjoint i
employment of bars or rails of wrought iron or steel and of pig metal, or for.
the employment of pig metal only.
Figures 1 to 9, on Sheet I., show my improved arrangement of furnaces for
producing steel directly from the ore. Figure 1 shows a longitudinal section,
through the furnace and regenerators on line 1, 1, Figure 5; Figure 2 shows
a transverse section on line 2, 2, Figure 5; Figure 3 shows an elevation of the..
furnace and section through the gas passages on line 3, 3, Figure 2; Figure 41
shews an elevation of the tapping hole side of the furnace; Figure 5-shows a
sectional plan on line 5, 5, Figure 1; and Figures 6 to 9 shew enlarged
details. Similar letters of reference indicate similar parts in each of the
Figures.
The gas producers (which are the same as described in the Specifications' to
former Letters Patent granted to me) are not shown on the Drawing; they
may be placed at a considerable distance from the furnace, the gas therefrom.
being conducted to the furnace through the flue A, and directed through the':
reversing valve B alternately into the regenerators C, C¹, whence after
becoming heated they pass into the furnace alternately at the right or left
hand side of the heated chamber D, at which points the gas meets the heated.
atmospheric air proceeding alternately from the regenerators E, E¹, and enters
into combustion with the same. The admission of atmospheric air into the
regenerators E, E¹, is regulated by the reversing valve B A¹ is, the flue..
through which the products of combustion escape. The roof and sides of the.
heated chamber or furnace D are constructed of the most refractory materials,
such as best silica or Dynas bricks, while the bottom or bed is formed by pre-
ference of a mixture of two descriptions of sand, the one being nearly pure
silica and practically infusible, and the other a red sand, which in being acted
upon by the beat of the furnace near the surface fuses and thus binds the.

page_text: white sand together so as to form a hard and impervious crust for the reception
of a bath of molten steel... A mixture of two or three parts of white sand with
one of red is found to answer best, but it is important that the two sands
should be well mixed and charged dry into the furnace. The surface of the
sand is formed so as to constitute the hollow bath shown on the Drawing, and
in order to give a certain thickness and solidity to the crust I charge the last
portions of sand in thin layers when the furnace is already at a full welding
heat. In the roof of the furnace are formed two circular orifices, through
which the interior of the furnace communicates with two vertical cylindrical
chambers F, F, which are constructed of shells of wrought iron lined with
brickwork, and are suspended from the upper flooring or stage G in order not
to press upon the heated arch of the furnace.. The joints between the arch
and these chambers are made good with clay. The upper ends of the chambers
F, F, are made to communicate with a chimney by means of pipes H, H¹;
provided with regulating dampers h, h¹; through the open upper ends of these
chambers two vertical. hoppers, pipes, or retorts I, I¹, pass down nearly to the
surface of the bed of the furnace, as shown; they are suspended from the tops
of the chambers F, F, the upper portions i thereof being constructed of cast
iron and slightly increasing in diameter in the downward direction, while the
lower portions are made of clay, such as is usually employed for making
steel melting pots. The clay cylinders i are attached to the iron pipes i by
means of bayonet joints, as shown at the enlarged details thereof at Figures
6 and 7, of which Figure 6 shews a section and plan of the clay cylinder,
while Figure 7 shows a sectional plan of the iron cylinder. These hoppers or
retorts: I, I', receive the ore with which the furnace is charged, and the
requisite reducing gases are conveyed, into the mass of ore contained therein
through small pipes J, J', descending through the hoppers. The reducing
gases may be derived from the gas producers before alluded to, in which case.
they are forced by a steam jet in the pipe K into the lower part of the
scrubber L, of which an enlarged vertical section is shown at Figure 8, and
which is filled with coke or other suitable loose material over which water is
made to trickle in continuous streams, which water escapes through an.
overflow 1, the object being to wash and purify the gases from vapours and
sulphurous acid, &c. The gases may also be passed over quicklime to complete.
the purification, and through a heating apparatus, if thought desirable,
before it reaches the cast-iron cross pipe M through the ascending pipe N,
whence it descends through the pipes J, J¹, as before described. These pipes
are. carried by the cross pipe M being dropped through openings in the top of
the latter provided with covers.m, m³, and made to rest with flanges upon the

page_text: inner bottom surface of the same, by which arrangement the pipes J, J', may
be readily removed and exchanged in case they are injured by the heat of the
lower parts of the hoppers. The cross pipe M can also be readily removed
and the hoppers themselves be raised in case of injury occurring to their lower
5. ends of pot clay, which are exposed to the heat of the furnace. The bayonet
joint between the clay and iron portions of the hoppers admits of the latter
being readily.exchanged in case of injury, one or more of them being kept
in readiness in an annealing stove.
.
The mode of working this furnace is as follows:-In heating the furnace
the open upper ends of the cylindrical chambers F, F1, are closed by covers,
which are replaced by the hoppers I, I, when a full white heat bas been
attained. As soon as the hoppers are in place a small charge of charcoal is:
introduced, which is followed by the ore or compound of ore and reducing.
agent and flux to be employed, until they are entirely filled. The gas supply:
pipes J, J, having likewise been placed in position a supply of reducing gas.
is turned on, which can be regulated according to circumstances by means of
the steam jet employed in forcing it on. The dampers h, h', of the flues H, H',:
are also then opened in order to cause a portion of the flames from the furnace
to pass up in the annular spaces surrounding the hoppers I, I, in the
chambers F, F, so as to heat the former to redness; at the same time also
pig metal is introduced into the furnace through the side openings 0, 0¹,
which metal in melting forms a bath of molten metal below the hoppers on the.
bed of the furnace. By the conjoint action of the reducing agents and of the
beat applied externally to the hoppers the iron ore is reduced to spongy iron,.
which in coming into contact with the metallic bath is readily absorbed and
dissolved therein, the earthy constituents rising to the surface of the bath in the
form of slag or scoria. In proportion as the spongy iron produced by réduction;
in the hoppers is dissolved fresh material is added at the top, and this in gra-
dually descending in the hoppers is in its turn reduced and dissolved. The heat
of the furnace being maintained at a steel melting heat it is necessary to.
observe from time to time whether the metallic bath remains fluid; if it should
commence to thicken additional cast iron is introduced at the side openings O
upon the sloping banks, whence the molten cast metal descends into the bath,
and supplies fresh carbon to the same. The scoria forming upon the surface
of the metallic bath is removed from time to time through the centre door P¹,.
which may be advantageously at a lower level than the side or charging
ivors P, as indicated in the modified arrangement of this furnace at Figures 15,
16, and 18 on Sheet II. When sufficient molten metal has accumulated upon
be bath discs of cast iron lined upon their under sides with clay, shown to an

page_text: enlarged scale in section and plan at Figure 9, are introduced upon the
surface of the ore in the hoppers. These discs are inade in two parts for the
convenience of introducing them without removing the gas supply pipes J, J¹,
having also for this purpose a central hole, as shown, and the two halves are
united by a strong wire R fastened through lugs and forming a loop, as
shown. When these discs have descended by the weight of the ore filled.
in upon them until they have passed the joint between the cast iron and clay
hoppers the wire connected thereto catches upon the gas pipe M and prevents
its further descent. The material below the discs having become absorbed
in the bath the latter is stirred and tested. The slag should be of a light-
brown or light green color, and contain little iron in combination. If it
should be heavy and dark in colour, and the metal bath below it thick and
partially set in masses of malleable metal, more cast iron bas to be charged in'
at the side doors or the hoppers O, and it will also be advisable to throw some
charcoal upon the fluid bath. The heat of the furnace must also be raised
to or maintained at a full steel melting heat, and the bath be stirred as soon
as the pig metal is melted. If the slag should remain dark; it is a proof that
insufficient flux has been charged with the ore to combine with the silica
generally contained in it, and quicklime should be added, which will readily
combine with the slag, liberating the iron and allowing the same to combine with
the metallic bath below. If much slag remains it should be removed by means:
of rakes through the centre door Pt, the cill plate of which is nearly on a level
with the métallic bath when full. A sample of the metallic bath is thereupon
taken out by means of a small ladle washed previously with plumbago. This
sample of metal is plunged into water while it is red hot, and is then broken
under a hammer and touched with a file. If it breaks toughly and if the file
touches it freely, it is a proof that the metal contains only from 0.1 to 0.2
per cent. of carbon, and is in the required condition; but if on the contrary
it breaks short or becomes glass hard it is necessary to stir the bath under
the influence of an oxidizing flame (by reducing the supply of gas) until the
proper condition it attained. This having been effected, from five to eight
per cent. of ferro-manganese or spiegel eisen is charged in at the side doors,
and the bathi is stirred gently as soon as it is melted, after which the bath
is ready for tapping. The precise amount of spiegel eisen to be. added
depends upon the temperature or the per-centage of carbon required.
The ladle T, shown in section at Figure 16 on Sheet II, in reference to
another. modification of the steel melting furnace, mounted upon wheels and
lined in the usual manner, and leated internally by means of a gas flame or
a coke fire, is moved in front of the furnace below the tapping hole S; the

page_text: loose sand' is then removed from the tapping hole and put on one side until
a portion of the hard crust in contact with the bath of metal is exposed,
which is thereupon pierced by a pointed iron bar in the lowest point, when
the metal runs into the ladle; the ladle is then moved upon the rails over
a casting pit, where moulds of a suitable form and size for the work required
are placed, which are filled one after the other by raising the stopper U by
means of a lever. The cast ingots thus obtained are hammered and rolled
in the usual manner, or the metal may be cast direct into dry clay moulds
of the form in which the metal is required, forming very strong castings.
In this latter case the per-centage of carbon of the metal should be increased
to one per cent. or more. The quality of the steel so produced may be
further modified by adding titanic acid;, manganese, or other substances to
the ore.
When the furnace is emptied of its charge and the bed of the
furnace has been repaired, if necessary by throwing in fresh sand and
filling up the tapping hole, the rods R holding the discs Q are cut; whereupon
these are forced down by the ore in the hoppers on to the bed of the furnace,
and a fresh charge of ore descends as before. It is however not in every
case necessary to introduce the discs Q at the end of every charge, in which
case the action of the hoppers will be strictly continuous. The clay hoppers ¹
may be dispensed with by making the cast-iron hoppers i continuous, and
supplying in themselves the cast iron requisite to form the metallic absorbing
bath. This arrangement is shown at Figures 10 and 11 on Sheet I., Figure
10 showing a longitudinal section and Figure 11 a transverse section of the
furnace, which in this case is provided with only one hopper, I, I, are the
cast-iron tubes or cylinders connected together by means of bayonet joints,
as shown at the enlarged section and plans at Figures 12 to 14, which tubes
are filled with the ore, and are passed down the chamber F to the bed of the
furnace D, where they are melted down with the ore as described. As the
tubes melt away and descend into the furnace fresh ones are attached at the
top from the platform G. The upper part of the chamber F does not in this
case communicate with a chimney, as in the previous arrangement, the
ascending gases through the same escaping into the atmosphere round the
descending hopper. The other parts of the furnace and the mode of operating
with the same are the same as described with reference to the previous
arrangement and need therefore not be again referred to:
Figures 15 to 19 on Sheet II. of the Drawings show another modification
of my improved furnace, whereby cast steel is prepared from a mixture of
bar iron, or old rails, or wrought iron or steel, and pig metal, or from pig
metal alone. Figure 15 shows a longitudinal section of the furnace 'on'

page_text: line 15, 15, Figure 19; Figure 16 shows a transverse section on line 16, 16,
Figure 19; Figure 17 shows a back elevation; Figure 18 shows a front
elevation; and Figure 19 shews a sectional plan on line 19, 19, Figure 15.
In this arrangement sloping hoppers I are substituted for the vertical hoppers
in the previous arrangement, down which hoppers bar iron or old rails are
slid from the platform G. so as to rest with their ends upon the bed of the
furnace. Pig metal is at the same time introduced through the side openings O,
so as in melting to form a bath in which the bar iron or rails dissolve; as the
latter are thus made gradually to slide down the hopper I a portion of the highly
heated products of combustion from the furnace are allowed to pass up the
hoppers, escaping at the open ends thereof after having .heated the wrought
iron to a red heat preparatory to its passing down into the bath. If cast iron
alone is employed white pig metal should be used, which is introduced into
the furnace in a similar manner to the bar iron down the hoppers I. In
this case the gas supplied to the furnace would be relatively diminished, and
the chimney draught increased, causing a current of intensely heated oxygen
to pass over the metal and to effect its decarbonization. This effect may be
increased by occasionally stirring the bath, and also by the introduction upon
the surface of the bath of oxides of iron, or by preference of magnetic sands
containing titanic acid, which latter will become absorbed and improve the
quality of the steel produced. A sufficient quantity of metal having accumulated
in the bath, and the proper chemical condition of the bath having been ascer-
tained by taking out a sample and regulated as before described from four to
eight per cent. of spiegel eisen is introduced through the side doors P or the
hoppers O, and the process of tapping, &c. is carried on in a similar manner
to that described with reference to the first arrangement.
Figures 20 to 22 on Sheet II. show my before-described improved con-
struction of kiln for calcining ores and line. Figure 20 shows a vertical
section on line X, X, Figure 22; Figure 21 shows a sectional plan on line Y, Y,
Figure 20; and Figure 22 shows a sectional plan on line Z, Z, Figure 20.
The kiln A which is provided with a.lining of fire-brick, as shown, has at its
base a conical projection B, through the centre of which is formed the passage
for combustible gas C which enters from the gas generators through the
flue D, and issues into the kiln from beneath the iron hood E, at the same
time combustible gas is also caused to pass from the flue D, through the
circular passage
F and up through the vertical passages G, whence it issues
through openings H at the circumference of the kiln. Assuming the kiln
to be charged with ore or limestone from the platform. I through the apertures.J,
and the lower part of the charge to be at a calcining heat, air entering through

page_text: the discharge apertures K at bottom will in rising up through the heated
calcined mass take up heat therefrom, and in coming into contact with the
combustible gas issuing at E and H will enter into combustion therewith,
effecting a considerable and equable heating of. the entire charge. without any
5. admixture of solid fuel being.requisite. The supply of gas through the apertures
at the circumference may be regulated by means of dampers L; the hot gaseous
products of combustion in passing up through the kiln impart their heat to
the charge in the upper part before escaping from the top. To prevent the
clogging of the charge of the kiln stoppered apertures M, M, N. N, are
formed round the upper part of the kiln accessible from the gallery O,
through which apertures tools may be introduced for prising the charge and
causing it to descend freely. Access is gained to the gas passages G from the
gallery O through apertures P provided with covers for the purpose of clearing
them out when necessary, and other apertures R provided with doors are also
formed at the bottoms of these gas passages, rendered accessible from the pit S.
The discharge openings K are provided with doors Q to regulate the draught
of air and the discharge of the calcined materials.
Having thus described the nature of my Invention, and, the best means
I am acquainted with of performing the same, I wish it to be understood that
what I claim is,
First. Making cast steel upon the open hearth of a furnace by effecting
simultaneously the reduction of iron ores in vertical heated hoppers, and the
dissolution of the reduced metal without exposing it to the flame in the
metallic bath provided in the furnace, substantially as herein-before described
with reference to Sheet I. of the accompanying Drawings.
Second. Making cast steel upon the open hearth of a furnace by causing
wrought iron, steel, or white cast iron to descend upon inclined planes or
through hoppers where they become gradually heated into a fluid bath of cast
iron under the influence of very intense beat, where they are dissolved and
converted into cast steel, substantially as described with reference to Figures 15
to 19 on Sheet II. of the accompanying Drawings.
.
Third. Applying regenerative gas furnaces to the operations set forth in
the first and second claims in such a manner that a portion of the products
of combustion are withdrawn to heat the materials descending into the
furnace by gravity, while the remaining products of combustion which have
not been reduced in temperature by contact with cold materials pass
through regenerators to the chimney in the usual manner, the effect being
hat the temperature of the furnace is not reduced by the introduction of such
cold materials.

page_text: Fourth. I claim in combination the general details of construction and
management of my improved furnaces, substantially as herein-before described.
Fifth. Constructing kilus for calcining ores, limestone, cement, and plaster
of Paris, wherein the required heat is produced by the combustion of air with
gaseous fuel made to enter the kiln both centrally and at the circumference at
some distance above the openings through which the air enters, substantially
as herein-before described with reference to Figures 20 to 22, on Sheet II. of
the accompanying.Drawings.
In witness whereof, I, the said Charles William Siemens, have hereunto
set my hand and seal, this Twenty-first day of February, in the year
of our Lord One thousand eight hundred and sixty-eight.
Witness,
THOS. TAYLOR,
20, Southampton Bldgs..
C. W. SIEMENS. (L.S.)