IMPROVEMENTS IN THE MANUFACTURE OF IRON AND STEEL
Year: 1877

page_text: LETTERS PATENT to Isaac Lowthian Bell, of Rounton Grange, in the County
of York, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF IRON
AND STEEL."
Sealed the 12th June 1877, and dated the 11th April 1877.
PROVISIONAL SPECIFICATION left by the said Isaac Lowthian Bell at the
Office of the Commissioners of Patents on the 11th April 1877.
ISAAC LOWTHIAN BELL, of Rounton Grange, in the County of York.
MENTS IN THE MANUFACTURE OF IRON AND STEEL."
" IMPROVE-
Most iron ores contain phosphorus, generally in the form of phosphoric acid,
which when exposed to the reducing agency of the blast furnace loses its oxygen,
leaving the phosphorus to combine with the pig iron.
Malleable iron when manufactured from pig containing an excessive quantity
of phosphorus is apt to be brittle, owing to the difficulty of sufficiently ridding the
metal under treatment of this substance.
Steel containing something under two-tenths of a unit per cent. of phosphorus
is unmanageable in the subsequent stages of its manufacture. In the Bessemer
converter and in the open-hearth furnaces no appreciable separation of phosphorus
takes place, hence pig iron containing much above one-tenth of a unit per cent. is
useless as a steel-making material.
I believe that the cause of this is due to the temperature of the puddling furnace
and that of the steel processes referred to being too elevated to permit the phos-
phorus to be carried off in the slags.
My Invention consists in exposing fluid cast iron to a bath of molten oxide of
iron at a much lower temperature than that employed in puddling iron. These
two substances are agitated together in any suitable way, but the mode which
I have found most effectual is to introduce the two into a revolving cylinder
of iron, lined or "fettled," as it is termed, like an ordinary rotating puddling
furnace.
To avoid cooling the melted iron and oxide I provide the revolving cylinder with
a fire-place and chimney, by means of which I can raise the temperature of the cylinder

page_text: before introducing the materials to be operated on, after which the heat is com-
pletely or partially shut off during the remainder of the process.
The moderate temperature at which the operation is carried on permits the
phosphorus to be more perfectly removed than happens at the more clevated tem-
perature of a puddling furnace, owing to a longer retention of the carbon, which
substance confers on pig iron its fusibility. In the event however of the pig iron
containing an excess of phosphorus the carbon may be so diminished in quantity
that consolidation takes place before the phosphorus is sufficiently well removed; in
such case I add a little more fluid cast iron to the portion partially dephosphorized
and continue the operation as before.
The purified iron may be then run out of the revolving cylinder as cast iron for
puddling, or the operation may be continued until the iron drops down, as it is
termed, having the composition of steel, or carried on still further until it contains
so little carbon as to constitute malleable iron.
At either of these desired stages I prefer freeing the product as completely as
possible from the adhering "cinder," which, with the phosphorus, has been trans-
ferred from the pig iron. "I do this because in attempting either to fuse or weld
the steel or iron, the temperature is such that a portion of the phosphorus is
re-absorbed by these substances from such cinder. The separation of metal from
cinder can be accomplished either by compression in suitable apparatus or by
immersing the mass in certain fusible compounds, on account of economy, those of
silica lime and alumina being preferred, which possess the power of rapidly com-
bining with oxide of iron.
The metal so cleansed may be then brought to a welding heat or melted down
into ingots in any of the well-known forms of furnace used for theso objects.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Isaac Lowthian Bell in the Great Seal Patent Office on the 11th
October 1877.
ISAAC LOWTHIAN BELL, of Rounton Grange, in the County of York. "IMPROVE-
MENTS IN THE MANUFACTURE OF IRON AND STEEL."
My said Invention has for its object the more effectually ridding of crude or pig
iron of its associated phosphorus than can with the same degree of certainty or
completeness be effected by the means at present in use. For this purpose the cast
iron is employed direct from the blast furnace, or is melted in a foundry cupola, or
in any of the well-known forms of apparatus for the fusion of metals.
The agent I make use of for the removal of the phosphorus is oxide of iron as
it exists in the ores of this metal, or as it occurs in certain bye-products from other
manufacturing operations. Among these latter may be cited slags from puddling,
balling, and other furnaces found in malleable iron works, or other factitious
substances in which oxide of iron is found in sufficient quantity for my purpose.
Ju the selection of the oxide of iron or compounds containing it I prefer, for
obvious reasons, thoso in which sulphur and phosphorus do not occur in excessive
quantities.
The oxide of iron may be melted in a cupola or other form of furnace for
obtaining a sufficiently high temperature. When a cupola or other kind of blast
furnace is employed care must be taken not to raise the heat to that point which
would cause too copious a reduction of the oxide of iron to the metallic state, as I
prefer simply fusing the compound containing the oxide.
Should the oxide of iron employed for carrying out my Invention consist of this
substance in so pure a form as to be easily reduced to the metallic condition; I
prefer adding silica or other earthy substance, either free or combined with oxide of

page_text: iron, as they are found in iron ores or iron slags, so as to ensure fusion at that
temperature I find best suited for my purpose.
I have found that when the heat of the iron and of the oxide resembles that at
which the metal is used for foundry purposes it answers extremely well.
The streams of melted oxide of iron and of cast iron may be conducted either
separately or together into a vessel intended for blending the two.
It is obvious that many forms of apparatus may be used for this purpose. A
revolving furnace, such as that proposed by Mr. Danks or by Mr. Crampton for
puddling iron, or that devised by Messrs. Godfrey and Howson for a similar object,
enables the operator to bring the two fluids rapidly into that intimate contact which
is required for the process. Any of these forms of furnaces also afford the means of
warming up the vessel in which the iron and oxide of iron are to be brought
together, so as to prevent the mixture being too rapidly cooled by the sides of the
apparatus, or in case it is desirable to retard the cooling of the contents of the
vessel; this can easily be done by the means used for maintaining a high tem-
perature when any of these furnaces are used for puddling iron. The operation is
continued at the moderate temperature herein-before described, care being taken to
keep it below that point at which carbon is rapidly removed from cast iron, for it'
is essential to the success of my Invention that the phosphorus should be almost
entirely oxidized and transferred to the oxide of iron before the carbon has been
greatly reduced in quantity.
In practice I have found, as already stated, that when the iron and oxide are
brought together at the temperature or thereabouts at which metal is run in an iron
foundry the cast iron under treatment loses almost the whole of its phosphorus, as
well as the greater portion of its silicon and sulphur, before its carbon has been so
lessened in quantity as to deprive it of its power to remain in a fluid condition
before the close of the operation.
In the event of the pig iron containing an unusual per centage of phosphorus, or
of the action being such as to incur a risk of the materials being thrown out of the
vessel by the ebullition, the fluid cast iron for each operation may be added at twice
or oftener, according to the nature of the case.
The quantity of oxide of iron employed should at least be sufficient to take up
the phosphorus of the iron without itself becoming unduly charged with this
impurity, and I consider that when the per centage of phosphorus amounts to seven
per cent. the oxide of iron becomes unfit for use, or at least that the employment of
so impure an oxide is undesirable.
When the two substances have been long enough in contact to effect the separation
of the phosphorus, which generally happens in about five or ten minutes, the
purified cast iron can be run out by a properly constructed tapping hole, if a Dank's
furnace or one similar in principle is employed, or by inclining the revolving vessel,
which is easily accomplished when the puddling furnace according to the con-
struction patented by Messrs. Godfrey & Howson is made use of.
Both oxide and iron can be run out, received in moulds, and separated in the
manner practised in an ordinary refinery or running-out fire; or if the oxide is not
so saturated with phosphorus that its action in purifying more iron is not seriously
impaired, a portion of it can be retained in the vessel and an additional quantity
added, varying in amount according to circumstances, after which the operation
must be conducted in the manner already described.
The purified iron may, in case it is so desired, be run 'direct into a furnace or
other form of apparatus, and converted direct into malleable iron or into steel by
any of the well-known methods in use for either of these processes.
Although the separation of carbon from cast iron is greatly retarded by the low
temperature at which phosphorus is best carried off by oxide of iron if the operation
be continued sufficiently long, the carbon may he so reduced in quantity that the
iron is converted into steel, or if continued a still longer time it passes into iron in
its malleable form.
Before applying the requisite heat in order to fuse or weld the steel or iron, as

page_text: the case may be, I prefer separating as far as possible the adhering oxide or cinder,
because in raising the temperature to effect either of these objects a portion of
the phosphorus is extremely apt to pass back again from the cinder to the steel
or iron.
The separation of cinder from metal can be accomplished either by compression
under a hammer or squeezer. It may also be done by immersing the metal in any
easily fusible compound, such as a silicate of lime and alumina, to which an alkali
may or may not be added. By this last-mentioned method the metal is in a great
measure cleansed from the oxide or cinder, after which it may be brought to a
welding heat or melted into ingots, in any of the well-known forms of furnace used
for these objects. Thus it will be seen that my method of treatment is essentially
as follows:-Melted cast iron is intimately mixed with melted oxide of iron in a
furnace or vessel, in which they are maintained at a suitable temperature, such that
no rapid separation of the carbon from the metal takes place, whilst the phosphorus
for the most part passes from the metal to the oxide, which having thus become
contaminated is removed from the metal, either before the cast iron is by the
separation of carbon converted into steel or wrought iron, or if the oxide so
contaminated is not removed before the conversion of the cast iron into wrought
iron or steel then it is removed before the heat is applied requisite to weld the iron
or fuse the steel.
Having thus described the nature of my said Invention, and the manner of per-
forming the same, I would have it understood that I claim as my improvements in
the manufacture of iron and steel, the separation of phosphorus from the metal,
substantially as described.
In witness whereof, I, the said Isaac Lowthian Bell, have hereunto set my
hand and seal, this Eighth day of October, in the year of our Lord One
thousand eight hundred and seventy-seven.