IMPROVEMENTS IN THE PRODUCTION OF IRON AND STEEL, AND IN PROVISIONAL SPECIFICATIONARATUSNECRE
Year: 1873

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 THE PRODUCTION OF IRON AND STEEL, AND IN
PROVISIONAL SPECIFICATION left by the said Charles William
Siemens at the Office of the Commissioners of Patents, with his
Petition, on the 11th December 1873.
I, CHARLES WILLIAM SIEMENS, of No. 3, Great George Street, West-
3 minster, in the County of Middlesex, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN THE PRODUCTION OF IRON AND
STEEL, AND IN FURNACES AND APPARATUS CONNECTED THEREWITH," to be as
follows:-
In the Specification of a Patent granted to me on the 3rd December,
1872, No. 3642, I described a method of producing iron and steel directly
from the ores, and a rotatory furnace for effecting the process.

page_text: My present Invention relates to improvements in the process described
in the said Specification, and in the construction and working of furnaces
and apparatus for effecting the same.
In producing iron or steel directly from ores I prefer to employ such
ore or mixture of ores as produce a gangue, which forms a fusible slag
with lime, alumina, and other bases, or when such ores cannot be
obtained I mix with the ores treated, which I prefer to be calcined, such
fluxing material as is necessary for the production of a fusible slag.
The charge of ore being heated as described in the Specification above
referred to, I add the reducing agent, which according to the present
Invention I prefer to be coal, wood, lignite, or peat which has been
charred in a partial manner, so that all the moisture and the more
volatile hydrocarbons have been removed, while sufficient hydrocarbons
remain to develop rich reducing gases at the higher temperature of the
furnace wherein the partially charred material is mixed with the
ore.
I will hereafter describe means of effecting such partial charring,
such means forming part of my present Invention.
When the reaction between the ore and the reducing agent has been
effected the iron produced exists in the form of partly coherent masses,
while the gangue is collected as a pool of fluid at the bottom of the
rotating chamber. This fluid is tapped off and the tapping hole is then
closed by a ball of plastic clay. Some cinder still adheres however
mechanically to the iron, which it is important to cleanse as completely
as possible from earthy matter before it is formed into compact balls.
For this purpose I throw over the metallic mass a quantity of pure iron
oxide, such as roll scale or rich hematite, or other ore, or a mixture of such
oxides or ore with sand to form a siliceous slag, which is favourable to
the welding together of the iron into a solid mass. Strong bases such as
soda may also be employed when it is desired to render the iron
chemically pure or free from sulphur and phosphorus for the production
of steel.
When merchant iron or puddled steel is to be produced it is necessary
to supply a small quantity of carbon to the metal. This I effect by
throwing over the mass while bubling from 1 to 3 per cent. of cast iron a
or spiegeleisen in a divided or granular condition. Cast-iron turnings
or borings may be used for this purpose, or pig metal or spiegeleisen,
which may be granulated as I will hereafter describe.

page_text: The addition of oxides to cleanse the metal of cinder may in some
cases be dispensed with, and likewise the addition of cast iron or spiegel
eisen, or both these portions of the process may be effected successively
as above set forth, the latter portion of the process having the effect of
imparting to the metal the quantity of carbon or carbon and manganese
desired for the quality of iron or steel to be produced.
When the metallic balls have been formed and removed from the
furnace to be hammered and rolled into bar iron or to be treated in a
steel melting furnace there remains in the furnace a quantity of slag
rich in iron. This may be tapped into a mould or receptacle in order to
be roasted and broken up and charged again with fresh ore into the
rotatory furnace, or it may be allowed to set in the furnace in order to
add to its lining in a manner which I will presently describe.
If instead of removing the balls cast steel is to be produced in the
rotatory furnace a larger quantity of divided or granulated pig metal or
of spiegel-eisen should be added than that required for the production
of wrought iron, the proportion depending on the amount of carbon or
carbon and manganese required in the steel. After this addition the
heat of the furnace has to be considerably raised so as to effect fusion
of the metal, which is thereupon tapped into moulds in the usual
manner.
My improvements in the furnaces and apparatus used in connection
with the process described above are of the following nature:-When
ore is charged into the rotatory furnace a portion of it flies off in dust,
which is carried by the draught into the regenerative chambers and tends
to obstruct their passages. To obviate this inconvenience I lead the
products of combustion from the throat of the rotatory furnace down a
descending flue to a chamber where solid particles are deposited, and
thence up an ascending flue to the upper part of each regenerator. I
provide the deposit chamber with a door for the occasional removal of the
matter deposited therein, which may be charged again along with the
ore into the rotatory furnace. The flues leading to and from the deposit
chambers being constructed of fire-brick may be regarded as extensions
or portions of the regenerators, increasing their efficacy while protecting
them against the accumulation of dust.
I construct the shell and lining of the rotatory chamber in the fol-
lowing manner : _ I form the outer shell with longitudinal ribs projecting.

page_text: inwards, and lay in this shell fire-brick to form a protecting lining about
three inches thick, the ribs serving to support the same. At each end of
the chamber where it tapers into a throat I make the lining of con-
siderably greater thickness, preferably of lumps of bauxite or very
aluminous clay made to fit closely round the end apertures, of which the
one serves for the inlet and outlet of flame and the other for the working
door. This protecting lining having been formed the furnace is heated
to redness when a quantity of pure oxide of iron, such as roll scale, rich
hematite ore, or purple ore (the residue of iron pyrites), or a mixture of
those substances is charged along with fifteen to thirty per cent. of iron
turnings or about five per cent. of coal or coke dust. The furnace is
then while slowly rotating heated up till the charge is fused, whereupon
jets of water are directed mostly on the under side of the shell. By this
means there is formed a dense deposit of solidified iron oxide on the
brick lining. This process is repeated till a cylindrical crust of sufficient
thickness is formed, such crust being extremely infusible.
In order to form flat places on the lining a smaller charge of the
lining material is fused and. the rotation of the chamber is stopped, the
heat is reduced, and the jets of water are directed on the under side so
as to cool the fused material which lies in a pool thereon, and which sets
so as to present the flat surface desired. And in this manner by stopping
the furnace at different points of its rotation several flats may be formed
on the interior. In forming the lining in this manner the interior
surface may be made to present projections by throwing into the fused
lining material before it sets lumps of chromate of iron or titanic ore, or
of bauxite, and such lumps may be arranged so as to divide the metal
afterwards treated in the furnace into two or more separate masses or
balls. For the lining in this manner of furnaces intended for the pro-
duction of steel within the rotator it is necessary to have the lining
highly refractory, and roll scale or other pure oxide of iron with an
admixture of iron turnings should only be used.
In a similar manner the lining may from time to time be repaired, and
the slag remaining after removing the puddled balls may for this purpose
be caused to set on the inner surface by cooling.
For producing the partially charred carbonaceous matter which I have
described above as being preferable for a reducing agent in the process
I utilize a portion of the waste heat of the gas producers in the following

page_text: manner-In the upcast shaft of the gas producer (which shaft for this
purpose may be enlarged) I place a cylindrical retort having a charging
shoot at the upper end and a discharging shoot at the lower end. I keep
this retort charged with coal, wood, lignite, or peat, or a mixture of
some of these materials, from time to time withdrawing by the lower
shoot a quantity partially charred during its descent along the retort
exposed to the heat of the gases passing from the producer. The gases
evolved from the materials in the retort escape by an orifice at its top,
and mingle with the gases from the producer. In this manner a portion
of the waste heat of the gases from the producer is utilised, while an
additional quantity of gas is generated and the carbonaceous material is so
far charred as to be free from its lighter hydrocarbons, retaining still
such a proportion of the heavier hydrocarbons as render it more active
in the operation of reducing ores as described above.
For preparing the divided or granulated pig iron or spiegeleisen
which has to be added to the material in the rotative furnace after
reduction, I direct a jet of the fused matter on a horizontal rotating
disc mounted in a vessel of water, whereby it is scattered in small
portions and sets in a divided or granular condition.
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 10th June 1874.
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 Eleventh day of December, in the year
of our Lord One thousand eight hundred and seventy-three, in the
thirty-seventh year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said Charles William Siemens,
Her special license 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,

page_text: "
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 PRODUCTION OF IRON AND
STEEL, AND IN FURNACES AND APPARATUS CONNECTED THEREWITH,'
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 :—
In the Specification of a Patent granted to me on the 3rd December
1872, No. 3642, I described a method of producing iron and steel
directly from the ores, and a rotatory furnace for effecting the process.
My present Invention relates to improvements in the process described
in the said Specification, and in the construction and working of
furnaces and apparatus for effecting the same.
In producing iron or steel directly from ores I prefer to employ such
ore or mixture of ores as produce a gangue which forms a fusible slag
with lime, alumina, and other bases, or when such ores cannot be
obtained I mix with the ores treated, which I prefer to be calcined, such
fluxing material as is necessary for the production of a fusible slag. The
charge of ore being heated as described in the Specification above
referred to, I add the reducing agent which, according to the present.
Invention, I prefer to be coal, wood, lignite, or peat which has been
charred in a partial manner so that all the moisture and the more
volatile hydrocarbons have been removed, while sufficient hydro-
carbons remain to develop rich reducing gases at the higher temperature

page_text: of the furnace wherein the partly charred material is mixed with
the ore.
I will hereafter describe means of effecting such partial charring, such
means forming part of my present Invention.
When the reaction between the ore and the reducing agent has been
effected the iron produced exists in the form of partly coherent masses,
while the gangue is collected as a pool of fluid at the bottom of the
rotating chamber. This fluid is tapped off and the tapping hole is then
closed by a ball of plastic clay. Some cinder still adheres however
mechanically to the iron which it is important to cleanse as completely
as possible from earthy matter before it is formed into compact balls.
For this purpose I throw over the metallic mass a quantity of pure iron
oxide such as roll scale or rich hematite or other ore, or a mixture of
such oxides or ore with sand to form a siliceous slag which is favourable
to the welding together of the iron into a solid mass. Magnetic ores
being readily fusible are well suited for this purpose. Strong bases such
as soda may also be employed when it is desired to render the iron
chemically pure or free from sulphur and phosphorus for the production
of steel. At this stage of the process it is preferred to diminish the
supply of air to the furnace so as to render the flame powerfully reducing
in its action. A like diminution of the air supply should be resorted to
when the mass in the furnace is observed to produce fluid cinder too
freely or to slide over the lining.
When merchant iron or puddled steel is to be produced it is necessary
to supply a small quantity of carbon to the metal. This I effect by
throwing over the mass while beginning to form into balls from 1 to 3
per cent. of cast iron or spiegeleisen in a divided or granular condition.
Cast-iron turnings or borings may be used for this purpose, or pig metal
or spiegeleisen which may be granulated as I will hereafter describe..
Spiegeleisen is preferred for this purpose as it sets up an active
ebullition throughout the mass of the partially formed balls, mechanically
expelling the slag and substituting a cinder rich in manganese. In
many cases purification may be effected in this manner without the
preliminary washing with oxides described above.
The addition of oxides to cleanse the metal of cinder may in some cases
be dispensed with, and likewise the addition of cast iron or spiegeleisen,
or both these portions of the process may be effected successively as

page_text: above set forth, the latter portion of the process having the effect of
imparting to the metal the quantity of carbon or carbon and manganese
desired for the quality of iron or steel to be produced. The simultaneous
washing and carburetting of the metal may be effected by adding a
mixture of the oxides or pure ores with the granulated pig or spiegel-
eisen.
When the metallic balls have been formed and removed from the
furnace to be hammered and rolled into bar iron or to be treated in a
steel melting furnace, there remains in the furnace a quantity of slag
which when ores or oxides are employed as above described may be
rich in iron. This slag may be tapped into a mould or receptacle in.
order to be roasted and broken up and charged again with fresh ore
into the rotatory furnace, or it may be allowed to set in the furnace in
order to add to its lining in a manner which I will presently describe.
If instead of removing the balls cast steel is to be produced in the
rotatory furnace a larger quantity of divided or granulated pig metal or
of spiegeleisen should be added than that required for the production of
wrought iron, the proportion depending on the amount of carbon or
carbon and manganese required in the steel. After this addition the
heat of the furnace has to be considerably raised so as to effect fusion
of the metal which is thereupon tapped into the moulds in the usual
manner.
If
The precise mode of conducting the process described above depends
to a great extent upon the nature of the ore under treatment.
the ore is comparatively rich and pure a good heat may be maintained
throughout, and the addition of a small per centage of granulated pig
iron or spiegeleisen is all that is necessary for the production of
malleable iron. If the ore is easily fusible the heat has to be checked
when fusion commences, which is best accomplished by shutting off
the supply of air, and thus producing a highly reducing atmosphere
within the rotative chamber.
Another way of checking the heat of the mass under operation and of
increasing the reducing action at this stage of the process consists in
throwing in a quantity of granulated pig iron or cast-iron turnings, this
addition being independent of the final addition of granulated pig iron
or spiegeleisen. If the ore is rich in such impurities as sulphur and
phosphorus the temperature should be kept more moderate throughout

page_text: the operation, and thus the reduction. of these hurtful substances is
almost entirely prevented and a very pure iron is obtained. The iron so
produced is not hot enough to be hammered and rolled in the usual
manner of producing puddled bar but should be consolidated by means
of squeezing apparatus and then transferred to a reheating furnace in
order to raise the metal to a full welding heat before it is passed through
the rolls.
My improvements in the furnaces and apparatus used in connection with
the process described above, are of the following nature:-When ore is
charged into the rotatory furnace a portion of it flies off in dust which is
carried by the draught into the regenerative chambers, and tends to
obstruct their passages.
To obviate this inconvenience I lead the
products of combustion from the throat of the rotatory furnace down a
descending flue to a chamber where solid particles are deposited; and
thence up an ascending flue to the upper part of each regenerator. . I
provide each deposit chamber with a door for the occasional removal of
the matter deposited therein, which may be charged again along with
the ore into the rotatory furnace. The flues leading to and from the
deposit chambers being constructed of fire-brick may be regarded as
extensions or portions of the regenerators, increasing their efficacy while
protecting them against the accumulation of dust.
The Figures on Sheet I. of the accompanying Drawings shew the
construction and arrangement of such deposit chambers in combination
with the rotatory furnace and its four regenerative chambers..
Fig. 1 is a longitudinal section on the line Z, Z, of Fig. 2, which is a
sectional plan partly on the line Z¹, Z', and partly on Z, Z³, of Fig. 1;
Fig. 3 is a transverse section partly on the line Z³, Z³, and partly
on Z, Z, of Fig. 1; Fig. 4 is a front view of the furnace, and Fig. 5
is part of a transverse section through the rotatory chamber thereof on
the line Z, Z, Figs. 1 and 2.
A is the rotatory chamber of the form, and mounted and worked in the
manner described in the Specification above referred to; B, B, are
portions of the four regenerative chambers, each of which is provided
with a deposit chamber C consisting of a descending and ascending
channel with a space at bottom for the reception of the dust carried in.
suspension with the products of combustion when they issue from the
throat of the rotatory chamber. The dust deposited in these chambers.

page_text: is removed from time to time by the doors c. As the deposit chambers C
present a considerable amount of surface which is heated by the products
of combustion escaping through them from the furnace and which
serves to heat the gas and air passing through them on their way to the
furnace they act as portions of the regenerative chambers which may
have their surface proportionally reduced.
•
I construct the shell and lining of the rotatory chamber in the
following manner :- I form the outer shell with longitudinal ribs pro-
jecting inwards, and lay in this shell fire-brick or bauxite to form a
protecting lining about three inches thick, the ribs serving to support the
same. At each end of the chamber where it tapers into a throat I make
the lining of considerably greater thickness, preferably of lumps of
bouxite or very aluminous clay, made to fit closely round the end
apertures, of which the one serves for the inlet and outlet of flame, and
the other for the working door. This protecting lining having been
formed the furnace is heated to redness, when a quantity of pure oxide
of iron, such as roll scale, rich hematite ore, or purple ore (the residue
of iron pyrites), or a mixture of those substances is charged along with
fifteen to thirty per cent. of iron turnings, or about five per cent. of coal
or coke dust. The furnace is then, while slowly rotating, heated up till
the charge is fused, whereupon jets of water are directed mostly on the
under side of the shell. By this means there is formed a dense deposit
of solidified iron oxide on the brick lining. This process is repeated till
a cylindrical crust of sufficient thickness is formed, such crust being
extremely infusible.
In order to form flat places on the lining a smaller charge of the
lining material is fused, and the rotation of the chamber is stopped,
the heat is reduced, and the jets of water are directed on the under
side, so as to cool the fused material which lies in a pool thereon,
and which sets so as to present the flat surface desired; and in this
manner by stopping the furnace at different points of its rotation several
flats may be formed on the interior. In forming the lining in this
manner the interior surface may be made to present projections by
throwing into the fused lining material, before it sets, lumps of chromate
of iron or titanic ore, or of pure iron oxides, and such lumps may be a
arranged so as to divide the metal afterwards treated in the furnace into
two or more separate masses or balls. For the lining in this manner of
furnaces intended for the production of steel, within the rotator, it is

page_text: pure
necessary to have the lining highly refractory, and roll scale or other
oxide of iron with an admixture of iron turnings should only be used.
In a similar manner the lining may from time to time be repaired,
and the slag remaining after removing the puddled balls may for this
purpose be caused to set on the inner surface by cooling. •
In Figs. 1, 2, and 5, of Sheet I., a, a, represent the longitudinal ribs
for supporting the primary lining a¹ of fire-brick or bauxite, upon which
is formed the inner lining a² of fused ferruginous material, which may
be caused to set either to present a cylindrical surface, or to form flat
places in the interior periphery of the furnace, as indicated by the dotted
line a³, Fig. 5, in the manner described above.
For producing the partially charred carbonaceous matter which I
have described above as being preferable for a reducing agent in the
process, I utilise a portion of the waste heat of the gas producers in the
following manner:-In the upcast shaft of the gas producer (which
shaft for this purpose may be enlarged) I place a retort having a
charging shoot at the upper end, and a discharging shoot at the lower
end. I keep this retort charged with coal, wood, lignite, or peat, or a
mixture of some of these materials, from time to time withdrawing by
the lower shoot a quantity partially charred during its descent along the
retort exposed to the heat of the gases passing from the producer. The
gases evolved from the materials in the retort escape by an orifice at its
top, and may be allowed either to mingle with the gases from the
producer, or may be conducted elsewhere to be used separately. In this
manner a portion of the waste heat of the gases from the producer is
utilised, while an additional quantity of gas is generated, and the
carbonaceous material is so far charred as to be free from its lighter
hydrocarbons, retaining still such a proportion of the heavier hydro-
carbons as render it more active in the operation of reducing ores, as
described above.
Figs. 6 and 7, Sheet II., represent respectively a longitudinal and a
transverse section on the lines Z', Z, Z, Z, of the apparatus for effecting
the partial charring arranged in the uptake U of a block of gas pro-
ducers G, G, of ordinary construction. The uptake U by which the hot
gases pass from the producers is enlarged, if necessary, and within it is
placed the retort R, so as to be heated by those gases in their passage
along the uptake. At the top is a feeding door r, by which the carbon-

page_text: aceous material to be charred is from time to time introduced, and at
the bottom is a delivery door 7 by which the material partially charred
in its passage down the retort is from time to time removed. A pipe p
leads off the rich gas produced from the material in the retort, which
gas may be used for illuminating or other purposes, or may be mingled
with the gases delivered from the producers.
For preparing the divided or granulated pig iron or spiegeleisen
which has to be added to the material in the rotative furnace after
reduction, I direct a jet of the fused matter on a horizontal rotating dise
mounted in a vessel of water, whereby it is scattered in small portions
and sets in a divided or granular condition.
Fig. 8, Sheet II., represents a vertical section of the apparatus for
granulating the pig iron or spiegeleisen. It consists of a water trough T
with a sloping bottom and door t, in the middle of which trough is
mounted a vertical shaft S, which is caused to revolve rapidly by bevil
or other suitable gearing. On the top of this shaft is fixed a disc or
wheel W with radial ribs, as shewn in the plan view, Fig. 9. A spout X
is placed above the trough, with an aperture immediately over the
wheel W. By this spout the molten pig iron or spiegeleisen is run
from a cupola or other furnace, and descends in a stream upon the
revolving wheel W, whereby it is scattered in a divided condition among
the water of the trough, and being cooled sinks in a granulated form to
the bottom, whence it is removed from time to time by the door t.
Spiegeleisen may be granulated by the use of this apparatus. It may,
however, be produced in a form sufficiently divided for use in the
process, as described above, without fusion, by heating it to redness,
chilling it by immersion in cold water, and then subjecting it to the
action of stampers or other crushing apparatus.
Having thus described the nature of my Invention, and in what
manner the same is to be performed, I claim,-
First. The use as herein described of partially charred coal, wood,
lignite, or peat, for the purpose of reducing iron ores in a rotative
furnace.
Second. The utilisation of the waste heat of the gas producers, for the
purpose of effecting the partial charring of the reducing agents above
referred to, substantially as herein described.

page_text: Third. The method; substantially as herein described, of washing or
cleansing from earthy matter the balls of iron produced in a rotative
furnace by the addition of fusible ores after tapping off the gangue.
Fourth. The treatment of iron ores when reduced, and forming into
balls by the addition of spiegeleisen or other granulated pig metal,
substantially in the manner and for the purposes herein set forth.
Fifth. The use for regenerative gas furnaces of deposit chambers, sub-
stantially as herein described in reference to Figs. 1, 2, 3, and 4 of the
accompanying Drawings.
Sixth. The method of lining rotative iron furnaces by fusing ferruginous
materials on a primary lining of brick or bauxite, and causing the same
to set by means of water jets directed on the lower side of the furnace,
so as to form an inner refractory lining with such irregularities as may
be desired, substantially as herein described.
In witness whereof, I, the said Charles William Siemens, have
hereunto set my hand and seal, this Tenth day of June, in
the year of our Lord One thousand eight hundred and seventy-
four.
C. WILLIAM SIEMENS. (L.S.)