IMPROVEMENTS IN THE MANUFACTURE OF CAST STEEL
Year: 1859

page_text: LETTERS PATENT to Robert Mushet, of Coleford, in the County of
Gloucester, Metallurgist, for the Invention of "IMPROVEMENTS IN THE
MANUFACTURE OF CAST STEEL."
Sealed the 17th June 1859, and dated the 15th January 1859.
PROVISIONAL SPECIFICATION left by the said Robert Mushet at the
Office of the Commissioners of Patents, with his Petition, on the
15th January 1859.
I, ROBERT MUSHET, of Coleford; in the County of Gloucester, Metallurgist,
do hereby declare the nature of my said Invention for "IMPROVEMENTS IN
THE MANUFACTURE OF CAST STEEL," to be as follows:-
When pig iron or cast iron, in the stage of manufacture in which it is called
refined metal, or cast iron in any other state, has been granulated by any
convenient process, and mixed with a quantity of pulverized oxyde of iron or
iron ore amounting to from ten to twenty per centum by weight of the,
granulated cast iron operated upon, the mixture, when introduced into clay pots
or crucibles placed in an ordinary steel melting furnace, may be therein heated
until the said mixture shall have become melted and liquid, when it may be.

page_text: poured into suitable ingot moulds to form ingots of cast steel, in the usual
manner practised by steel melters.
Now, I have discovered that by adding to such a mixture of granular cast
iron and oxyde of iron or iron ore, and by combining therewith in the melting
pot or crucible, a triple compound consisting of or containing iron, carbon, and
manganese, the quality of the cast steel obtained by melting the mixture of
granulated cast iron and iron ore, or oxyde of iron, is much improved; and
my Invention consists in adding the said triple compound to the said mixture
of cast iron and oxyde of iron, or iron ore, under the conditions herein
described. The quantity of the triple compound to be thus added varies
according to the nature of the materials, and according to the quality of the
steel intended to be produced; but I find that from two to twenty per centum
by weight of the triple compound is sufficient to produce with the granulated
cast iron, and iron ore, or oxyde of iron, when mixed, melted, and combined
together in the melting pot, the different qualities of cast steel ordinarily
required in commerce.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Robert Mushet in the Great Seal Patent Office on the
14th July 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
MUSHET, of Coleford, in the County of Gloucester, Metallurgist, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifteenth day of January, in the year of our Lord
One thousand eight hundred and fifty-nine, in the twenty-second year of
Her reign, did, for Herself, Her heirs and successors, give. and grant unto
me, the said Robert Mushet, Her special licence that I, the said Robert
Mushet, my executors, administrators, and assigns, or such others as I, the
said Robert Mushet, 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 THE MANUFACTURE OF CAST STEEL," upon the condition (amongst others)
that I, the said Robert Mushet; my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and seals,

page_text: 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 Robert Mushet, do hereby declare the
nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof, that is to say:
When pig iron or cast iron in the stage of manufacture in which it is
called "refined metal," or cast iron in any other state, has been granulated by
any convenient process, and mixed with a quantity of pulverized oxide of iron,
or iron ore consisting essentially of peroxide of iron, or of the peroxide and
protoxide of iron combined, amounting to from ten to twenty per centum by
weight of the granulated cast iron operated upon, and the said mixture is
introduced into clay melting pots or crucibles placed in, an ordinary steel
melting furnace, and therein heated until the said mixture melts, the said
melted mixture forms steel, which may be poured into suitable ingot moulds-
to form ingots of cast steel, in the usual manner practised by steel melters:
Now, I have discovered that by adding to such a mixture of granular cast:
iron and oxide of iron or iron ore, and by combining therewith in the melting
pot or crucible, a triple compound consisting of or containing iron, carbon, and
manganese, the quality of the cast steel obtained by melting the mixture of
granulated cast iron and iron ore, or oxyde of iron, is much improved; and my
Invention consists in adding the said triple compound to the said mixture of.
cast iron and oxyde of iron, or iron ore, under the conditions herein described.
The quantity of the triple compound to be thus added varies according to the
nature of the materials, and according to the quality of the steel intended to
be produced; but I find that from two to twenty per centum by weight of the
triple compound is sufficient to produce with the granulated cast iron and iron.
ore, or oxyde of iron, when melted and combined together in the melting pot,
the different qualities of cast steel ordinarily required in commerce.
In carrying my Invention into effect I proceed in the following manner :-
I take pig iron or refined cast iron, or other cast iron, and I prepare it for my
process by granulating it in any convenient manner. I prefer, however, to
granulate the said pig iron or refined cast iron by heating lumps of it in a
reverberatory or other furnace to a temperature somewhat short of their
melting point, in which state the iron is found to be soft and friable. I then
place these beated lumps of pig iron, refined cast iron, or other cast iron in
ron mortars, and beat or stamp upon them with iron pestles until the said

page_text: lumps of iron are reduced to à coarse powder, being careful, however, to
pulverize the said cast iron as finely and evenly as possible.
I do not claim as of my said Invention any method for granulating the pig
or cast iron. The pig iron, refined cast iron, or other cast iron which I prefer
to use is such as has been smelted or reduced from rich hematite, specular,
-spathose, or magnetic iron ore, free or nearly free from sulphur and
phosphorous by means of charcoal fuel; but, nevertheless, pig iron, refined
cast iron, or other cast iron smelted or reduced from pure hematites, spathose,
or magnetic iron ores with a coal fuel free from sulphur, or coke fuel prepared
from washed coal, may likewise be advantageously used for my process.
I prepare the iron ore or oxide of iron for my process by pulverizing,
stamping, or crushing it by any convenient method, so as to reduce it to a fine
powder; and in practice I find that when reduced so as to pass through a
riddle or sieve of thirty meshes per linear, or nine hundred meshes per square
inch, it affords very good results.
The iron ores which I prefer to use are the purest hematite iron ores or
magnetic oxides of iron, such as contain the largest per-centage of iron, and.
the least admixture of earthy matters, especially lime and clay, and I carefully
avoid using spathose iron ores, or other iron ores containing much manganese,
as the oxydes of manganese act injuriously upon the insides of the melting
.pots or crucibles. The triple compound, consisting of or containing iron,
carbon, and manganese, which I prefer to employ, is the white crystalline pig
iron metal, produced in Rhenish Prussia by smelting spathose iron ores and
hematites, containing much manganese with charcoal fuel, in the blast
furnace, and which pig iron metal is termed "spiegel eisen." This spiegel
eisen contains besides iron and carbon from one to eight per centum of man-
ganese. The said triple compound may also be produced from manganesic
iron ores smelted with coal or coke fuel in the blast furnace; but such coal
should be as free as possible from sulphur, and the coke should be prepared
from washed coal. I do not, however, claim as of my said Invention any
process or method for obtaining the said triple compound of iron, carbon,
and manganese, which may be procured in any convenient and economical
manner. I prepare the said triple compound for my purposes by breaking it
up into small pieces suitable for packing into the melting pots or crucibles
or I granulate it for that purpose by any convenient method. To thirty
pounds of grey pig iron, known in commerce as No. 1 iron, and granulated
as I have described, I add five pounds of the purest pulverized hematite o
magnetic iron ore, and three pounds of the triple compound of iron, carbon
.and manganese broken into small fragments or granulated. I mix these

page_text: substances thoroughly, and introduce the mixture into a suitable melting pot
or crucible placed in a suitable melting furnace, and I heat the said mixture
therein until it is melted and converted into steel. The melting pot is then
withdrawn from the furnace, and the steel is poured into a ingot or other
mould in the usual manner. The melting pots or crucibles which I use, and
the melting furnaces in which they are placed and heated, are such as are
usually employed by manufacturers of cast steel. I do not confine myself
to the proportions described, as the proportions must be varied according to
the nature of the materials employed, and the degree of hardness it is intended
that the steel shall possess. But by increasing the relative proportion of the
triple compound of iron, carbon, and manganese added whilst the proportions
of the other materials, that is to say, of the granulated pig iron and pulverized
iron ore remain unaltered, the hardness of the steel will be increased; or if
the relative proportion of the pulverized iron ore be increased, whilst the
proportions of granulated pig iron and the triple compound remain unchanged,
the hardness of the steel will be diminished, and thus, by altering the relative
proportions either of the triple compound of iron, carbon, and manganese, or
those of the pulverized iron ore, the hardness of the steel may be regulated,
and steel of any degree of hardness or softness required in commerce may
be readily obtained. To thirty-six pounds of refined cast iron metal, granu-
lated as herein-before described; I add three pounds of pulverized iron ore,
and three pounds of the triple compound of iron, carbon, and manganese
broken into small fragments. I mix these substances together thoroughly,
and I then introduce the mixture into a melting pot or crucible placed in a
suitable melting furnace, and I heat the said mixture therein until it is
melted and converted into steel; I then pour the steel in the usual manner
into ingot or other moulds. I do not confine myself to these proportions,
as the proportions must be varied according to the nature of the refined
cast-iron metal employed, and the degree of hardness which it is intended
that the steel shall possess. But the bardness of the steel may be increased
by increasing the relative proportion of the triple compound of iron, carbon,
and manganese added to the granulated refined cast iron and the pul-
verized iron ore, or the hardness of the steel produced may be increased
by diminishing the relative proportions of pulverized iron ore or oxyde of
iron mixed with the granulated refined cast iron and the triple compound,
and by varying the proportions of the several ingredients the various
qualities of steel required in commerce are readily obtained.
In place of adding in the first instance the whole of the triple compound of
iron, carbon, and manganese to the granulated cast iron and pulverized iron

page_text: ore or oxyde of iron, and then melting them together, I sometimes add at
first only a portion of the said triple compound, and when the mixture is
melted, I remove the lid or cover of the melting pot or crucible, and pour in
the remaining portion of the said triple compound, which has been previously
melted in any convenient manner, either in a separate pot or crucible, or in
an air furnace or otherwise. I then withdraw the melting pot from the
furnace, and pour the steel into an ingot or other mould in the usual manner;
I sometimes also melt the granulated cast iron or refined cast iron with the
pulverized iron ore, and having previously melted in a separate crucible or
furnace the requisite quantity of the triple, compound of iron, carbon, and
manganese, I pour it from a crucible or ladle into the melted steel contained
in the melting pot or crucible; I then withdraw the melting pot from the
When
melting furnace, and pour the steel into moulds in the usual manner.
the melted triple compound of iron, carbon, and manganese is thus added
to the melted granulated cast iron and pulverized iron ore in the melting pot
or crucible, the mixture may be stirred with a rod of iron or steel to hasten
the combination of the said triple compound with the steel, but this is only
necessary when the quantity operated upon is large. I prefer to use pig iron,
refined cast iron, or other cast iron which is as free as possible from sulphur,
phosphrous, and, silicon, such as has been prepared from pure hematite,
specular, spathose, or magnetic iron ores with fuel free or nearly free from
sulphur; scrap iron or scrap steel may be added to the mixture of granulated
cast iron, pulverized iron ore, or oxide of iron, and the triple compound of iron,
carbon, and manganese, but such addition forms no part of my Invention,
neither is it essential to the success of my process. Oxide of manganese and
other fluxes may also be added, but I avoid the use of fluxes excepting when
more or less
special circumstances require them to be used, as they are
injurious to the insides of the melting pots, and are not in the least degred
essential to the success of my process under ordinary circumstances.
Having thus described the nature of my Invention and the manner in which
I carry it into effect, I wish it to be understood that I do not claim as of my
said Invention the manufacture of cast steel from granular cast iron in mixture
with iron ore or oxide of iron; but what I claim as my Invention is the
addition of a triple compound consisting of or containing iron, carbon, and
manganese to cast steel produced by melting granulated cast iron or granulate
refined cast iron and pulverized iron ore or oxyde of iron, so that the sai
triple compound may be melted and combined with the cast steel in the
melting pots or crucibles, in order thereby to improve the quality of the steel
that is to say, when cast steel is prepared by melting a mixture of granula

page_text: cast iron or refined cast iron and oxyde of iron or iron ore, I claim to improve
the said cast steel by the addition of a triple compound of iron, carbon, and
manganese melted and combined in the melting pot or crucible with the
said cast steel.
In witness whereof, I, the said Robert Mushet, have hereunto set my
hand and seal, this Fourth day of June, in the year of our Lord One
thousand eight hundred and fifty-nine.
Witnesses,
EDwD. M. MUSHET,
Coleford, Gloucestershire,
BROOKLYN MUSHET,
Coleford, Gloucestershire.
ROBT. MUSHET. (L.S.)