IMPROVEMENTS IN PRODUCING CAST STEEL, AND IN TREATING IRON ORES BAN Mam Dwanson
Year: 1871

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 PRODUCING CAST STEEL, AND IN TREATING IRON ORES
BAN Mam Dwanson
A
wn ADDADA MITO ANDY AVED
ני
Sealed the 28th April 1871, and dated the 2nd February 1871.
PROVISIONAL SPECIFICATION left by the said Charles William
Siemens at the Office of the Commissioners of Patents, with his
Petition, on the 2nd February 1871.
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 PRODUCING CAST STEEL, AND IN
TREATING IRON Ores for that Purpose, as also in THE FURNACES AND Apparatus
' EMPLOYED," to be as follows:-
In the Specification to my Patent, No. 594, of 1870, I described a
method of producing cast steel from iron, ores by forming lumps, either
by the fusion of such ores or by compression of crushed ores mixed with
clay and carbonaceous substances, and by exposing such lumps to heat

page_text: entire reduction of the ore before introducing the lumps thus formed and
prepared in an open hearth steel melting furnace described in the said
Specification.
My present Invention has for its object the production of loaves of
reduced iron suitable for carrying out the above-named steel making
process, by separating in the first place the pieces or nuts from the small
or pulverulent ore in passing the mixed ore over a sieve. The pieces or
nuts may be introduced together with a sufficient proportion of coke
or other carbonaceous matter into a double arched or hot store furnace,
as described in my Specification above referred to, until under the
influence of sufficient heat and time their reduction into metallic or
spongy iron is effected. Or the reduction of the pieces or nuts may
be more advantageously effected by filling them into the upper end of
a vertical or inclined shaft of brickwork, near the bottom of which
a separate but communicating chamber is provided, where coke, charcoal,
or coal is subjected to imperfect combustion by a limited introduction
of atmospheric air or of oxygen in other combinations. The hot reducing
gases thus produced in ascending through the ore causes its gradual
- reduction, but at a certain elevation atmospheric air is permitted to
enter the vertical shaft effecting the combustion of the remaining
reducing gases, and thus producing a considerable elevation of tem-
perature, while the final products of combustion escape at the top of
the ore shaft comparatively cool, being deprived of their heat by the
incoming raw ore, the reduced ore being withdrawn from time to time
through sutable doors at the bottom of the shaft. The raw ore in
descending is first calcined and heated considerably in contact with
flame produced by the combustion of the ascending gases, until the
point of incoming air is reached, whence downward it passes through an
atmosphere of highly reducing gases. A steam blast may be used with
advantage to actuate the production of the reducing gases in the com-
municating chamber before mentioned. The small or pulverulent
portion of the ore is mixed with lime or other fluxing material, and
is reduced into a fluid condition in a furnace similar to that described
in the Specification to my Patent, No. 594, of 1870. Moulds are
provided as described in the same last-mentioned Patent, which moulds
being first filled with pieces or nuts of reduced ore, with or without the
addition of coke or other solid carbonaceous matter are brought under

page_text: a stream of the melted ore, in order to be consolidated into loaves,
consisting mostly of reduced iron containing also fluxing materials.
•
In addition to the ore reducing and ore melting furnace a cupola or
other furnace is also provided where pig metal is melted, which melted
pig metal is poured into some of the moulds filled with the reduced iron
in the form of nuts, whereby loaves containing a large proportion of
reduced ores are produced which may still contain sufficient carbon to
render them fusible when exposed to intense heat. The object of the
cast iron is to form an envelope for the reduced ore so as to protect this
from the immediate action of the flames when introduced into the steel
melting furnace. The two descriptions of loaves thus produced are
either placed into hot store furnaces until they are required in the steel
melting furnace, or they are at once brought into the melting furnace.
The latter furnace is of similar construction to that described in my
former Patent No. 594 of 1870, but the bed is made in the following
manner: A lining of brickwork is placed upon the cast-iron plates forming
the bottom of the chamber upon which blocks of cast steel or iron of
considerable size are so placed as to form a border or rim with a level
edge all round except at the points where the furnace is intended to be
tapped and charged. The upper surface of these blocks is covered over
by highly refractory bricks of nearly pure silica or alumina. If silica
bricks are used, the bottom of the melting chamber is also formed of
silica. For this purpose the furnace is brought up to a full white heat
and a mixture of white sand with from 2 to 4 per cent. of fine glass
powder is introduced dry, and in thin layers, sufficient time being
allowed between the charges to cause the glass powder of the one layer
to melt and set the mixture before the next layer is introduced. Or,
a suitable mixture of sands may be used to effect the same tendency to
set under the influence of intense heat. Or if bauxite or pure alumina
is available this is calcined, crushed, and mixed with from 2 to 4 per
cent. of glass powder and introduced into the furnace in the same
manner as just described. The bed thus formed is made nearly hori-
zontal, inclining gently towards the tapping hole, and its surface is raised
to within 6 inches of the upper edge of the steel blocks forming the sides
of the chamber, the object of these being to confine the bath of metal
and of slag by vertical metallic sides and to prevent the destructive
action which the wash of the liquid bath is found to exercise upon a
sloping bed of silica or alumina. The furnace being thus prepared the
2

page_text: '
heated loaves of reduced ore are introduced and distributed over the
surface of the bed, care being taken to intermix loaves bound together
with pig metal with others bound with fused ore, in such proportion that
when the whole are melted a metallic bath containing only from one-
tenth to three-tenths per cent. of carbon with a neutral slag upon it is
formed. This final condition is regulated by the relative number of the
kinds of loaves employed and can be. finally adjusted by taking samples
and by adding more of the one or the other kind. Pig metal, fluxing
materials, or scrap metal may also be added to obtain the required
condition of the bath. This condition being realised it is necessary to
impart to the metallic bath from one-tenth to three-tenths per cent. of
manganese in order to render the metal malleable, to effect which special
loaves are prepared which are formed of ores rich in manganese which
are subjected to a reducing action in a separate muffle or reducing shaft
such as before described and bound together with cast iron poured into the
moulds as before described, which cast iron may by preference contain
manganese being a poor description of spiegel eisen. In dissolving these
loaves in the bath manganese may be imparted to it in the requisite
proportion when the metal is ready for being tapped in the usual
manner. If the ores used contain a considerable proportion of earthy
constituents the slag formed may be removed by skimming or tapping at
intervals during the operation of melting the loaves and of adjusting the
chemical condition of the bath.
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 2nd-August 1871.
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 Second day of February, in the year
of our Lord One thousand eight hundred and seventy-one, in the thirty-
fourth year of Her reign, did for Herself, Her 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, adminis-

page_text: trators, 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 PRODUCING CAST STEEL, AND IN TREATING IRON ORES FOR
THAT PURPOSE, AS ALSO IN THE FURNACES AND APPARATUS EMPLOYED," 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 imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Charles William Siemens, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement, reference being had to the Drawing here-
unto annexed, and to the figures and letters marked thereon, (that is
to say):
:-
In the Specification of my Patent No. 594 of 1870, I described a
method of producing cast steel from iron ores by forming lumps either by
the fusion of such ores or by compression of crushed ores mixed with
clay and carbonaceous substances and by exposing such lumps to heat in
a hot store or double arch furnace in order to effect the partial or entire
reduction of the ore before introducing the lumps thus formed and
prepared in an open hearth steel melting furnace described in the said
Specification.
My present Invention has for its object the production of loaves of
reduced iron ore suitable for carrying out the above-named steel making
process by separating in the first place the pieces or nuts from the small
or pulverulent ore in passing the mixed ore over a sieve. The pieces or
nuts may be introduced together with a sufficient proportion of coke or
other carbonaceous matter into a double arched or hot store furnace as
described in my Specification above referred to until under the influence
of sufficient heat and time their reduction into metallic or spongy iron is
effected. Or the reduction of the pieces or nuts may be more advan-

page_text: tageously effected by filling them by preference with the addition of a
certain proportion of coke or charcoal or other solid carbonaceous matter
into the upper end of a vertical or inclined shaft of brickwork near the
bottom of which a separate but communicating chamber is provided
where coke, charcoal, wood, or coal is subjected to imperfect combustion
by a limited introduction of atmospheric air or of oxygen in other com-
binations. The hot reducing gases thus produced in ascending through
the ore causes its gradual reduction (the reducing quality being restored
to it or maintained by coming again and again into contact with the
ignited coke or other carbonaceous matter mixed with the ore), but at a
certain elevation atmospheric air is permitted to enter or is forced into
the vertical shaft effecting the combustion of the remaining reducing
gases, and thus producing a considerable elevation of temperature while
the final products of combustion escape at the top of the ore shaft
comparatively cool, being deprived of their heat by the incoming raw ore.
The reduced ore being withdrawn from time to time through suitable
doors at the bottom of the shaft, the raw ore in descending is first
calcined and heated considerably in contact with flame produced by the
combustion of the ascending gases until the point of incoming air is
reached whence downward it passes through an atmosphere of highly
reducing gases. A steam blast may be used with advantage to actuate
the production of the reducing gases in the communicating chamber
before mentioned and to promote the combustion of the gases near the
top of the shaft. The small or pulverulent portion of the ore is mixed
with lime, clay, or other fluxing material and is reduced into a fluid
condition in a furnace similar to that described in the Specification to
my Patent No. 594 of 1870. Moulds are provided as described in the
same last-mentioned Patent, which moulds being first filled with picces
or nuts of reduced ore with or without the addition of coke or other solid
carbonaceous or fluxing materials are brought under a stream of the
melted ore in order to be consolidated into loaves consisting mostly of
reduced iron but containing also fluxing materials.
In addition to the ore reducing and ore melting furnace a cupola or
blast furnace is also provided where pig metal is melted, which melted
pig metal is poured into some of the moulds filled with the reduced iron
ore in the form of nuts whereby loaves containing a large proportion of
reduced ores are produced which may still contain sufficient carbon to
render them fusible when exposed to intense heat. The object of the

page_text: cast iron is to form an envelope for the reduced ore so as to protect this
from the immediate action of the flame when introduced into the steel
melting furnace. The two descriptions of loaves thus produced are either
placed into hot store furnaces until they are required in the steel melting
furnace or they are at once brought into the melting furnace. The
latter furnace is of similar construction to that described in my former
Patent, No. 594 of 1870, but the bed is made in the following manner :-
A lining of brickwork is placed upon the cast-iron plates forming the
bottom of the chamber around which blocks the 'cast steel of considerable
size are so placed into frames of cast iron exposed to the cooling influence.
of currents of atmospheric air as to form a border or rim with a level
edge all round, except at the point where the furnace is intended to be
tapped. The upper surface of these blocks is covered over by highly
refractory bricks of nearly pure silica or alumina. If silica bricks are
used the bottom of the melting chamber is also formed of silica. For
this purpose the furnace is brought up to a full white heat and a mixture
of white sand with from 1 to 3 per. cent. of fine glass powder is intro-
duced dry and in thin layers, sufficient time being allowed between the
charges to cause the glass powder of the one layer to melt and set the
mixture before the next layer is introduced. Or a suitable mixture of
sand may be used to effect the same tendency to set under the influence
of intense heat. The bed thus formed is made nearly horizontal inclining
gently towards the tapping hole and its surface is raised to within
6 inches of the upper edge of the steel blocks forming the sides of the
chamber, the object of these being to confine the bath of metal and of
slag by vertical metallic sides and to prevent the destructive action which
the wash of the liquid bath is found to exercise upon a sloping bed of
silica or alumina. In order however to protect the metallic sides and at
the same time to prevent the refrigeration of the bath, the sand bottom is
made to rise abruptly against the sides so as to cover the metallic surface,
which in its turn prevents the sand from melting through its cooling
influence. The furnace being thus prepared the heated loaves of reduced
ore are introduced and distributed in greater or smaller number over the
surface of the bed, care being taken to intermix loaves bound together
with pig metal with others bound with fused ore in such proportion that
when the whole are melted a metallic bath containing finally only from
one-tenth to two-tenths per. cent. of carbon with a neutral slag upon it
is formed. This final condition is regulated by the relative number of

page_text: the kinds of loaves employed, and can be finally adjusted by taking.
samples and by adding more of the one or the other kind. Pig metal,
fluxing materials, or scrap métal may also be added to obtain the required
condition of the bath. This condition being realized it is necessary to
impart to the metallic bath from two-tenths to four-tenths per. cent. of
_manganese, besides carbon in order to render the metal malleable, to
effect which special loaves are prepared which are formed of ores rich in
manganese, which are subjected to a reducing action in a separate muffle
or reducing shaft, such as before described, and bound together with cast
iron pourèd into the moulds as before described, which cast iron may by
preference contain manganese being a poor description of spiegel eisen.
In dissolving these loaves in the bath manganese is imparted to it in the
requisite proportion after which the metal is ready for being tapped in
the usual manner. If the ores used contain a considerable proportion
of earthy constituents the slag formed may be removed by skimming or
tapping at intervals during the operation of melting the loaves and of
adjusting the chemical condition of the bath.
Or the operation may be modified by commencing with a bath of pig
metal in the steel melting furnace, into which the loaves as before
described are introduced seriatim until a sufficient quantity of fluid
metal containing only a fractional amount of carbon is produced which is
thereupon brought to the proper per-centages of manganese and carbon,
cither by adding spiegel eisen with or without the addition of refined
metal for the supply of carbon only, or by adding manganese loaves as
before described.
Or the operation may be modified by charging, first, chiefly loaves
consisting of reduced iron ore bound together with pig metal, and by
following up with an increasing proportion of loaves bound together
with melted ore, or melted ore only may be employed. In taking the
pig metal employed in this process directly from the blast furnace I
adopt the arrangement of tapping the metal from the blast furnace into
a ladle mounted upon wheels, which ladle is then passed upon rails over
a series of moulds previously prepared and filled with reduced ores upon
which the fluid metal is poured through stoppered holes at the bottom of
the ladle.
On the accompanying Sheet of Drawings, Figures 1 to 4, shew the
construction of my before-described combined gas generator and furnace

page_text: or kiln for calcining and reducing iron ores. Figure 1 shows a vertical
section of the furnace and gas generator on line 1-1, Figure 2; Figure 2
shews a vertical section on line 2-2, Figure 1; Figure 3 shews a
sectional plan on lines 3-3, 3-3³, Figure 1; and Figure 4 shows a
sectional plan on line 4-4, Figure 1. Similar letters of reference
indicate similar parts in each of the Figures.
A is the vertical shaft into the upper end of which the ore mixed
with from 10 to 20 per cent. of coke, charcoal, or other fuel is in-
troduced from the platform B through the side door C in the charging
chamber D. The shaft A widens out somewhat from the top down
to a point near the lower end, as shewn, from which point it again
contracts and terminates in the enlarged chamber E, with bed F
sloping slightly down to the discharging doors G. At the back end of
the chamber E are two passages H, H, communicating with the gas gene-.
rator I, which is of the same construction as described by me in my
previous Patents. Through these passages II, H, the carbonaceous
gases pass from the gas generator into the chamber E and vertical
shaft A. A portion of the gases can also be made to pass through the
passages J (capable of being closed by slides K) into the enclosed
spaces L beneath the chamber E whence they rise through the gratings M
into the chamber. Surrounding the lower portion of the vertical shaft A
are arranged zig-zag passages N, N, into which a portion of the com--
bustible gases enter from the chamber E and are there made to enter
into combustion with atmospheric air passing through side apertures O, 0,.
whereby the lower portion of the shaft is heated somewhat so as to
accelerate the action of the reducing gases upon the ore which is more
particularly necessary on commencing operations. The products of
combustion pass up from the passages N through lues N₁ at the corners
and escape at N2 into the top of the shaft, dampers being provided for
regulating or closing the flues. Above the passages N are formed
lateral stoppered apertures P, P, for the introduction of atmospheric air
into the upper part of the shaft as before described, and air is also forced
into the central portion of the shaft through the pipe Q so as to bring.
about a perfect combustion of the carbonaceous gases passing up through
the mass of ore. The pipe Q is enclosed in the charging chamber D
by a strong casing or heating chamber R into which the air is forced
from the pipe S and from which it finds its way into the pipe Q through

page_text: the open upper end thereof, but lateral orifices may also be provided
to effect a greater distribution of the air amongst the ore. The top of
the casing R can be removed and the pipe Q be drawn out and replaced
by a new one should the lower end thereof be burnt away in course of
time. As the ore mixed with a small portion of carbonaceous matter
descends in the shaft A it is firstly heated to a considerable degree in
the upper part thereof by the combustion of gas and air that takes
place there, and on passing gradually below the air holes P it is brought
in contact in a highly heated condition with the ascending hot re-
ducing gases as before described (the reducing power of which is main-
tained by the presence of the coke charged with the ore) and eventually
arrives in a reduced condition on the bed F and gratings M whence it is
withdrawn from time to time through the doors G into moulds T in which
it is formed into loaves by pouring either pig metal or melted ore
over it as herein-before described. The grating M has for its object
the separation of the portion of reduced iron which has fallen into dust
and which would prevent the formation of concrete blocks if allowed
to pass into the moulds. This broken ore is taken out from time to time
through the door and is passed to the ore melting furnace.
The gas
producer also communicates with the chamber below the grating through
a slide valve, and gas passes through the grating into the the shaft,
enveloping the reduced iron to the last in order to prevent the reoxidation
through infiltration of atmospheric air.
The production of the reducing gases in the generators I may be
accelerated if desired by the introduction of a blast of air which may
be conveniently produced by means of apparatus such as was described
in the Specification to my former Patent, No. 3255 of 1870. The hot
gaseous products of the combustion taking place in the upper part of
the shaft A after rising through the mass of raw ore in the charging
chamber D and imparting the greater portion of their heat thereto
finally escape through the hood U into the atmosphere.
Figures 5 and 6 shew my before-described improved construction of
steel melting furnace; Figure 5 shews a longitudinal section partly on
line 5-5 and partly on line 5-5ª, Figure 6, and Figure 6 shows a
transverse section on line 6-6, Figure 5. The bed of the furnace is
formed of a lining of brickwork V placed upon the cast-iron frame
plates W, cooled externally by the free passage of air, as shewn, upon
which lining is laid a thick bed X composed of a mixture of white sand

page_text: and glass powder or of a mixture of sands, and prepared as herein-before
described. Round the edges of this bed are placed (excepting at the
tapping hole a) thick blocks of cast steel or of partially or wholly
decarburized iron Z carried by the cast-iron frame plates W, which
blocks are covered in with a coating of the consolidated sand X, as
shewn, so as to protect them from the action of the bath, whereas the
blocks Z protect the sand bottom from melting through its cooling
influence being sufficiently refractory to resist the action of the flame
where the sand bottom has melted away; b is the charging door through
which the loaves c prepared as herein-before described are introduced
on to the bed of the furnace.
The other parts of the furnace are similar in construction to those
described in my before-mentioned Patent, and need therefore not be
further referred to. Figure 7 shews a general plan of the arrangement of
steel works which I prefer to employ for carrying out my before-
described process of making steel: d, d, are two lines of rails along
which are arranged, firstly, my before-described ore reducing furnace e,
secondly, the ore melting furnace f described in my before-mentioned
Patent, No. 594 of 1870, thirdly, a cupola 9 for supplying the melted
cast iron to the moulds as before described, and fourthly, the hot store h
described in my aforesaid Patent for keeping the prepared loaves hot if
they are not required immediately in the melting furnace. At the end
of the lines of rails & may be a series of steel melting furnaces i with a
line of rails j, with turntable k, upon which the carriages with the
prepared loaves are run from the rails d to the charging doors 7 of the
furnaces. The chief object of forming the concreted loaves is to protect
the reduced iron from the action of the flame within the steel melting
furnace which would cause its reoxidation and contamination with
sulphur. The whole process is carried out to the best advantage in
pouring the fluid pig metal from the blast furnace upon the reduced iron
as herein-before described, and charging converted pig loaves thus pro-
duced while hot into the steel melting furnace, adding as many loaves
consolidated with molten ore as are found necessary to produce a liquid
containing from one-tenth to two-tenths per cent. of carbon, which bath
is thereupon dealt with as before described.
drcenihed the noturn of my Invention. and in what

page_text: do not confine myself to the precise form of apparatus herein-before
described, but what I claim is,-
First. Forming for the purpose of manufacturing cast steel concrete
blocks of reduced iron ore and of melted ores containing certain pro-
portions of fluxing materials, substantially as herein-before described.
Second. Forming for the purpose of manufacturing cast steel concrete
blocks of reduced iron ore and of fluid pig metal, substantially as herein-
before described.
Third. Forming concrete blocks or loaves of pig metal (containing
manganese by preference) and of partially reduced iron ore rich in
manganese to be charged into the steel melting furnace towards the end
of each operation, substantially as herein-before described.
Fourth. Effecting the reduction of iron ores for the manufacture of
cast steel by charging the same in combination with solid carbonaceous
matter through a vertical or inclined shaft supplied at the lower end
with heated and highly reducing gases from a gas producer, and by
effecting the introduction of atmospheric air in adjustable quantities near
the upper end of the shaft, substantially as herein-before described with
reference to Figures 1 to 4 of the accompanying Drawings.
Fifth. Constructing the bottom or hearth of an open hearth steel
melting furnace by placing blocks of steel or partially or wholly decar-
burized iron upon cast-iron frame plates exposed to cooling currents of
air, and by forming upon the said framework a consolidated mass of
highly refractory material, substantially as herein-before described.
Sixth. Forming a metallic bath of cast steel on the furnace hearth by 2
introducing under the influence of intense heat concreted loaves of
reduced iron ores bound together respectively with pig metal and with
melted ore with or without the addition of pig metal, such different
loaves being used in such proportions that a fluid metallic bath
containing only a fractional per-centage of carbon results, to which 3
bath ferro-manganese or pig metal and manganese is added in
order to produce malleable cast steel, substantially as herein-before
described.

page_text: herein-before described.
In witness whereof, I, the said Charles William Siemens have here-
unto set my hand and seal, this Twenty-ninth day of July,
in the year of our Lord One thousand eight hundred and seventy-
one.
C. WILLIAM SIEMENS. (L.S.)