PURIFYING CAST IRON
Year: 1878

page_text: LETTERS PATENT to Otto Helmholtz, of Düsseldorf, in the Empire of Germany,
for the Invention of "PURIFYING CAST IRON,"
PROVISIONAL SPECIFICATION left by the said Otto Helmholtz at the Office
of the Commissioners of Patents on the 6th June 1878.
OTTO HELMHOLTZ, of Düsseldorf, in the Empire of Germany.
CAST IRON."
" PURIFYING
This Invention has for its object the purifying cast iron. The value of pig iron
mostly depends on its purity from phosphorus, and various ways have been
suggested for removing phosphorus from iron when fluid. Amongst others it has
been proposed to subject fluid iron to the action of slags containing oxides of iron,
but the results have not as yet been entirely satisfactory.
According to my Invention I cause a continuous thin stream of fluid iron to be
led slowly against and beneath a similar stream consisting especially of oxides of
iron. I will call, for the sake of abbreviation, these two streams the iron stream
and the cinder stream. At the beginning of its way the iron stream renders its
silicon to the opposing cinder stream which contains already phosphoric acid. The
iron stream meets in its further way the cinder stream more basic, and containing
more oxides of iron, renders its phosphorus as acid to it, and finally flows off
purified, whilst the cinder stream, after having dissolved, phosphoric acid and then
silica discharges itself at the contrary end, viz., at the beginning of the iron
stream.
There are circumstances under which the carbon begins to escape from the iron
before the purification of iron is finished. To avoid this I employ the following
means: I let the iron stream flow on some parts of its way upon a bottom
made of carbon; the other parts of the channel for the stream are made of cinder
and oxides of iron or lime.
If it is to be feared that the iron will come to nature even without the aid

page_text: of puddling, or if a higher carbonized product is wanted, the iron stream is led over
a greater length of carbon bottom for dissolving carbon during the operation,
whilst it renders upwards to the cinder stream silicon, phosphorus, and even
carbon.
If it is preferred however to produce a less carbonaceous iron (for instance, iron
for the Martin or the puddling process), the molten metal has to run on shorter
parts of its way over carbon and more over bottom of iron oxides. This process is
carried out practically by a reverberatory furnace, either fitted with the usual
coal burning grate or fired with gas. This last is shewn in the Drawings
annexed.
The molten pig flows through the opening a¹ (see Sheet 3) into the furnace and
through this by serpentine channels to the opposite end of the furnace, where it
flows off beneath a tymp. Likewise the cinder, after being brought through the
opening c¹ into the furnace, and having passed the channels in a contrary direction
of the iron, flows off through the hole e'.
The continuous iron stream is obtained either at the smelting furnace, blast
furnace, cupola, or any other, by not closing the tapping hole and running the
molten iron together with the slag, the latter directly flowing off again through the
hole e', or by employing a tymp like that of the purifying furnace beneath which
the iron flows off whilst the slag escapes through a separate tap hole on a higher
level.
The basement of the hearth consists of cast-iron plates which can be cooled
beneath by air. On these plates the dams are placed, between which either ores or
carbon are stamped, forming the bottom of the channels. During the working of
the furnace the sides and bottom of these channels are continually renewed by
fettling. Parts of this bottom I also in some cases make of basic earths, lime,
magnesia, clay, or mixtures of them, if no other chemical re-action is intended as
between the two streams themselves.
The dams, tymps, and all the parts which are exposed to melt off too rapidly can
be cooled as usual at puddling furnaces by means of water or air.
For keeping up the continuity of both the streams, or for varying the proportion
of ore bottom to carbon bottom, it is necessary from time to time to leave out some
part of the channels and to fettle its bottom. For this purpose doors and tap holes
are provided at each side of the furnace, and at the ends of each channel.
To repair for instance the channel f (see Sheet 1), break out the stopping
material at h¹, stop at the other end h¹ of the dam, and put in the two cross stops i¹
and . Then the contents of the channel can be tapped out beneath the doors, and
the channel newly fettled without interrupting the streams. For cleansing and
fettling also the end channels, the furnace must be provided on each side with the
tymp for the iron outlet, the inlet hole for slag, the outlet hole for slag, and the
inlet hole for iron. These auxiliary holes usually are closed, and not used but for
The cinder stream
repairing the end channels. Not every dam is fed with ore.
principally originates of the molten fettling, but besides this molten oxides of iron
can be introduced by the hole before mentioned.
The dams at the end of the iron stream are fed with material containing the
purest oxides of iron, then follow less pure oxide materials, and finally the dams
only are fettled with lime. The cinder stream therefore has the highest amount of
oxides at its beginning, receives in its course at first acid or phosphorus then lime,
and finally silica.
To use pig iron or oxides containing manganese is not excluded. They can be
brought into the furnace either liquid or placed in a solid state upon the dams for
melting down gradually.
The iron purified in the manner before described can be 'cast either in moulds or
accumulated in a warmed vessel.
If the material purified from phosphorus and silicon is to be used in the Siemens'-
Martiu process, where decarbonization costs time and money, I prefer to mix
pulverized iron oxides to the outflowing stream of iron,

page_text: The purified iron containing no silicon, the oxides find no opportunity to combine
with silica, but are reduced almost perfectly, whilst in the common Siemens' ore
process almost half the ore is lost by giving a silicate.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Otto Helmholtz in the Great Seal Patent Office on the 5th December
1878.
OTTO HELMHOLTZ, of Düsseldorf, in the Empire of Germany. " PURIFYING
CAST IRON."
The value of pig iron
various ways have been
Amongst others it has
This Invention has for its object the purifying cast iron.
mostly depends on its purity from phosphorus, and
suggested for removing phosphorus from iron when fluid.
been proposed to subject fluid iron to the action of slags containing oxides of iron,
but the results have not as yet been entirely satisfactory.
According to my Invention I cause a continuous thin stream of fluid iron to be
led slowly against and beneath a similar stream, consisting especially of oxides of
iron. I will call, for the sake of abbreviation, these two streams the iron stream
and the cinder stream. At the beginning of its way the iron stream renders its
silicon to the opposing cinder stream which contains already phosphoric acid. The
iron stream meets in its further way the cinder stream more basic, and containing
more oxides of iron, renders its phosphorus as acid to it, and finally flows off
purified, whilst the cinder stream, after having dissolved, phosphoric acid and then
silica discharges itself at the contrary end, viz., at the beginning of the iron
stream.
There are circumstances under which the carbon begins to escape from the iron
before the purification of iron is finished. To avoid this I employ the following
means:-I let the iron stream flow on some parts of its way upon a bottom made
of carbon, the other parts of the channel for the stream are made of cinder and
oxides of iron or lime.
If it is to be feared that the iron will come to nature even without the aid of
puddling, or if a higher carbonised product is wanted, the iron stream is led over
a greater length of carbon bottom for dissolving carbon during the operation,
whilst it renders upwards to the cinder stream silicon, phosphorus, and even
carbon.
If it is preferred however to produce a less carbonaceous iron (for instance, iron
for the Martin or the puddling process) the molten metal has to run on shorter
parts of its way over carbon, and more over bottom of iron oxides. This process
is carried out practically by a reverberatory furnace, either fitted with the usual
coal burning grate or fired with gas. This last is shown in the Drawings
annexed.
The Figure on Sheet I. of the accompanying Drawings represents a horizontal
section of the furnace; the Figure on Sheet II. is a longitudinal section of the same,
taken on the line a, b, see Sheet I.; and the three Figures on Sheet III. represent
transverse sections taken on the line c, d, e, f, and g, h, i, k, see Sheet I.
The furnace is of the type of the usual reverberatory furnaces and fired with gas,

page_text: it can however, if preferred, also be constructed with a coal burning grate. At each
side of the one end of the furnace are an inlet and an outlet hole a', e', arranged ono
above the other, and at each side of the other end are an outlet hole with a tymp b¹,
and above it an inlet hole c', as is shown in Figure g, h, i, k, of Sheet III.
The hearth of the furnace is provided with a suitable number of dams in
transverse direction, and in such manner that a fluid mass brought in at the one
end of the furnace must flow in a serpentine to the other end, as clearly is shown on
Sheet I.
The dams as well as the tymps are cooled by means of water running through
cast-iron channels, as shown in section e, f, and i, k, on Sheet III.
The molten pig flows through the opening a' into the furnace and through this
by serpentine channels to the opposite end of the furnace, where it flows off
beneath a tymp. Likewise the cinder after being brought through the opening c²
into the furnace, and having passed the channels in a contrary direction of the iron,
flows off through the hole e¹.
The continuous iron stream is obtained either at the smelting furnace, blast
furnace, cupola, or any other, by not closing the tapping hole and running the
molten iron together with the slag, the latter directly flowing off again through the
hole e, or by employing a tymp like that of the purifying furnace, beneath which
the iron flows off, whilst the slag escapes through a separate tap hole on a higher
level.
The basement of the hearth consists of cast-iron plates, which can be cooled
beneath by air. On these plates the dams are placed, between which either ores or
carbon are stamped, forming the bottom of the channels. During the working of
the furnace the sides and bottom of these channels are continually renewed by
fettling; parts of this bottom I also in some cases make of basic earths, lime,
magnesia, clay, or mixtures of them, if no other chemical re-action is intended as
between the two streams themselves.
The dams, tymps, and all the parts which are exposed to melt off too rapidly can
be cooled as usual at puddling furnaces by means of water or air.
For keeping up the continuity of both the streams, or for varying the proportion
of ore bottom to carbon bottom, it is necessary from time to time to leave out some
parts of the channels and to fettle its bottom. For this purpose doors and tap holes
are provided at each side of the furnace and at the ends of each channel.
To repair for instance the channel f (see Sheet 1), break out the stopping material
at h¹, stop at the other end h¹ of the dam, and put in the two cross stops i¹ and kļ
Then the contents of the channel can be tapped out beneath the doors, and the
channel newly fettled without interrupting the streams. For cleansing and fettling
also the end channels the furnace must be provided on each side with the tymp for
the iron outlet, the inlet hole for slag, the outlet hole for slag, and the inlet hole for
iron. These auxiliary holes usually are closed and not used but for repairing the end
channels. Now every dam is fed with ore. The cinder stream principally originates
of the molten fettling, but, besides this, molten oxides of iron can be introduced by
the hole before mentioned.
The dams at the end of the iron stream are fed with material containing the
purest oxides of iron, then follow less pure oxide materials, and finally the dams
only are fettled with lime. The cinder stream therefore has the highest amount of
oxides at its beginning, receives in its course at first acid of phosphorus, then lime,
and finally silica.
To use pig iron or oxides containing manganese is not excluded. They can be.
brought into the furnace either liquid or placed in a solid state upon the dams for
melting down gradually.
The iron purified in the manner before described can be cast either in moulds or
accumulated in a warmed vessel.
If the material purified from phosphorus and silicon is to be used in the Siemens'-
Martin process, where decarbonization costs time and money, I prefer to mix
pulverized iron oxides to the outflowing stream of iron,

page_text: The purified iron containing no silicon, the oxides find no opportunity to
combine with silica, but are reduced almost perfectly, whilst in the common
Siemens' ore process almost half the ore is lost by giving a silicate.
Having thus described the nature of my Invention, and the manner of performing
the same,
I claim as my Invention for purifying cast iron,-
First. Conducting in a suitable furnace a stream of molten cinder above and
against a stream of molten metal, and utilizing the counter current for the purifica-
tion of the pig iron from phosphorus and silicon.
Second. Utilizing the smelting down of the fettling to produce a cinder stream,
the chemical constitution of which is altered from its beginning to end by varying
the constitution of the fettling in the same direction, so gradually supplying oxides
of iron, manganese, lime, or other alkaline earths for assisting the elimination of
silicon by forming alkaline silicates.
Third. Leading the stream of iron over a bottom which varies in different parts,
re-acting chemically or not re-acting, viz., varying between carbon and oxides of
iron, or lime, inagnesia, clay, or mixtures of these substances.
Fourth. Application of dams in the bath of metal, and establisment of a long
channel for the stream by those dams which consist either entirely of the re-agents
used for fettling, or of these with cooled cores.
Fifth. Purifying cast iron, substantially in the manner described, in a furnace
such as is represented by the Drawings.
In witness whereof, I, the said Otto Helmholtz, have hereunto set my
hand and seal, this Nineteenth day of November, in the year of our Lord
One thousand eight hundred and seventy-eight.
O. HELMHOLTZ. (L.S.)