AN IMPROVEMENT OR IMPROVEMENTS IN THE MANUFACTURE OF CAST STEEL
Year: 1858

page_text: LETTERS PATENT to Robert Mushet, of Coleford, in the County of
Gloucester, Metallurgist, for the Invention of "AN IMPROVEMENT OR
IMPROVEMENTS IN THE MANUFACTURE OF CAST STEEL."
Sealed the 18th February 1859, and dated the 22nd December 1858.
PROVISIONAL SPECIFICATION left by the said Robert Mushet at the
Office of the Commissioners of Patents, with his Petition, on the 22nd
December 1858.
I, ROBERT MUSHET, of Coleford, in the County of Gloucester, Metallurgist,
do hereby declare the nature of the said Invention for "AN IMPROVEMENT
OR IMPROVEMENTS IN THE MANUFACTURE OF CAST STEEL," to be as follows:-
My said Invention consists in manufacturing cast steel by melting together:
or combining when melted the following materials, that is to say, broken,
crushed, or granulated cast iron, whether pig or refined metal, deoxydized
iron ore or oxide of iron, and a metallic compound consisting of or containing
iron carbon and manganese. The said materials are melted in melting pots,
heated in a furnace of the kind ordinarily employed for melting steel. The
melted steel may be cast into ingots or other articles of any desired form. I
prefer to break, crush, or granulate the cast iron, so as to reduce it to the
state of gravel or coarse powder, as it is in this state more readily mixed with
the deoxydized iron ore, and can be more conveniently and closely packed-
into the melting pots or crucibles. In carrying my Invention into effect, I

page_text: prefer to employ the purest cast iron, that is to say, cast iron free or nearly
free from sulphur, phosphorous, and silicon.
The deoxydized iron ore which I employ is prepared by exposing the purest
iron ores, such as the magnetic, specular, or hematite ores, to a strong heat in
closed chambers, kilns, or furnaces, such, for example, as the ordinary furnaces
used for converting steel, and at the same time exposing them to the influence
or action of carbon or hydrogen or other reducing deoxidizing agents. By
this treatment the ore is almost or wliolly deoxýdized, that is to say, almost or
entirely deprived of its oxygen. The triple compound of iron, carbon, and
manganese may be prepared by smelting iron ores containing manganese;
but I prefer to employ the variety of white crystalline cast iron obtained in
Prussia from smelting ores of iron containing likewise much manganese, and
called "spiegel eisen," the said "spiegel eisen" containing iron, carbon, and
manganese.
I do not limit myself to any particular proportions of the several materials
employed, as the said proportions vary according to the quality of the materials,
the degree of deoxydization which the ore has undergone, and the properties it
is wished that the steel should possess; but I have found in practice that
when the cast iron called best grey charcoal pig iron is employed, the
following proportions answer very well, namely, ten parts by weight of broken
or granulated cast iron to twenty parts by weight of deoxydized iron ore, and
three parts by weight of the triple compound of iron, carbon, and manganese.
When the cast iron contains less carbon than grey charcoal pig iron, the
relative proportion of the cast iron may be increased. Thus I have found
that when white, mottled, and bright grey pig iron is used, the following pro-
portions answer well, namely, fifteen parts by weight of the broken or
granulated cast iron, fifteen parts by weight of the deoxydized iron ore,
and three parts by weight of the triple compound of iron, carbon,, and
manganese. When broken or granulated refined iron is used, I find the
following proportions afford a good result, namely, twenty parts by weight of
the broken or granulated refined iron, ten parts by weight of the deoxydized
iron ore, and three parts by weight of the triple compound of iron, carbon, and
manganese. Wrought or malleable iron scraps and steel scraps may be added
to the mixture of broken or granulated cast and deoxydized iron ores, and be
melted therewith into steel, and a small portion of oxide of manganese may
also be added as a flux, but I do not claim these additions as of my said
Invention, neither are they essential to its success.
•

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Robert Mushet in the Great Seal Patent Office on the
16th June 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 Twenty-second day of December, in the year of our
Lord One thousand eight hundred and fifty-eight, 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, ny 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 "AN IM-
PROVEMENT OR 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, 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 :-
:
My said Invention consists in manufacturing cast steel by melting together.
or combining when melted the following materials, that is to say, broken,
crushed, or granulated cast iron, whether pig iron or refined metal, deoxydized
iron ore or oxide of iron, and a metallic compound consisting of or containing
iron, carbon, and manganese. The said materials are melted in melting pots
or crucibles, heated in furnaces of the kind ordinarily employed for melting
steel. The steel produced by the melting together of the said materials may
be cast into ingots or into other articles of any desired form.

page_text: I prefer to break, crush, or granulate the cast iron so as to reduce it to the
state of small gravel or coarse powder, as it is in this state more readily mixed
with the deoxydized iron ore, and can be more conveniently and closely packed
into the melting pots or crucibles.
In carrying my Invention into effect, I prefer to employ the purest cast iron,
that is to say, cast iron free or nearly free from sulphur, phosphorus, and
silicon. The deoxydized iron ore which I employ is prepared by exposing the
purest iron ores, such as the magnetic, specular, or hematite ores, to a strong
heat in closed chambers, furnaces, or kilns, such, for example, as the ordinary
furnaces used for steel converting, and at the same time exposing them to the
influence or action of carbon or hydrogen or other reducing or deoxydizing
agent. By this treatment the ore is almost or wholly deoxydized, that is to
say, almost or entirely deprived of its oxygen.
The triple compound of iron, carbon, and manganese may be prepared by
smelting iron ores containing manganese, but I prefer to employ the variety of
white crystalline cast iron obtained in Prussia by smelting ores of iron con-
taining likewise much manganese, and called "spiegel eisen," the said
spiegel eisen" containing iron, carbon, and manganese.
I do not limit myself to any particular proportions of the several materials
employed, as the proportions which I employ vary according to the qualities
of the respective materials, the degree of deoxydization which the ore has
undergone, and the properties it is wished the steel should possess; but I have
found in practice that when the cast iron called best grey charcoal pig iron is
employed, the following proportions answer very well, namely, ten parts by
weight of broken or granulated cast iron to twenty parts by weight of
deoxydized iron ore and three parts by weight of the triple compound of iron,
carbon, and manganese. When the cast iron contains less carbon than grey
charcoal pig iron, the relative proportion of the cast iron may be increased;
thus I have found that when white, mottled, and bright grey pig iron or a
mixture of these varieties of cast iron is used, the following proportions answer
well, namely, fifteen parts by weight of the broken or granulated cast iron,
fifteen parts by weight of the deoxydized iron ore, and three parts by weight
of the triple compound of iron, carbon, and manganese. When broken or
granulated refined iron is used, I find the following proportions afford a good
result, namely, twenty parts by weight of the broken or granulated refined iron,
ten parts by weight of the deoxydized iron ore, and three parts by weight of
the triple compound of iron, carbon, and manganese. Wrought or malleable
iron scraps and steel scraps may be added to the mixture of broken or granu-

page_text: lated cast iron and deoxydized iron ore, and be melted therewith into steel,
and a small portion of oxyde of manganese may also be added as a flux; but
I do not claim these additions as of my said Invention, neither are they
essential to its success. I prepare the deoxydized iron ore for my process by
grinding, stamping, or crushing the said iron ore by means of edge runners,
stamps, or rollers, or in any other convenient or economical manner. I then
riddle or sieve the deoxydized iron ore, and winnow it so as to cleanse it from
the earthy matter and charcoal which are more or less mixed with it; when
thus purified, the deoxydized iron ore is ready for my process. I prepare
the triple compound of iron, carbon, and manganese, or spiegel eisen, by
breaking it up into small fragments not exceeding in size a hen's egg, and as
much smaller as they may happen to become during the breaking up, which I
effect by beating the spiegel eisen on an iron plate with a heavy hammer,
or it may be granulated by melting it and running it into water. I prepare
the cast iron for my process by heating lumps of it in a reverberatory or other
furnace to a heat somewhat short of the melting temperature, and I then
place the lumps in an iron mortar, and reduce them to the state of gravel or
coarse powder by beating and stamping upon them whilst softened the
heat with iron pestles, or the cast iron may be pulverized in any other con-
venient manner.
When the cast iron to be operated upon is grey charcoal pig iron of good
qualtity, I take about ten pounds of it pulverized, as I have already herein
described, and I take about twenty pounds of the prepared and purified
deoxydised iron ore. To these I add about three pounds of the prepared
triple compound of iron, carbon, and manganese, or spiegel eisen, and having
introduced these substances into a melting pot or crucible placed in a suitable
melting furnace, I heat them therein until they are melted into steel, when
the said steel is to be poured into an ingot mould or other mould in the usual
manner.
When the cast iron to be operated upon is white, mottled, or grey charcoal
pig iron, or a mixture of any of these, I take about fifteen pounds of the cast
iron pulverized as I have described, and fifteen pounds of the prepared purified
deoxydized iron ore, and to these I add about three pounds of the triple còm-
pound of iron, carbon, and manganese, or "spiegel eisen ;" I then introduce these
substances into a melting pot or crucible placed in a suitable melting furnace,
and I heat them therein until they are melted into steel, when I withdraw the
melting pot and pour the contents into an ingot or other mould in the usual
manner. When refined cast iron is used, I take about twenty pounds of it

page_text: "
pulverized and prepared as I have herein-before described, and I take about
ten pounds of the prepared and purified deoxydized iron ore, and to these I
add about three pounds of the triple compound of iron, carbon, and manganese,
or spiegel eisen, broken small, and I then introduce these substances into a
melting pot or crucible placed in a suitable melting furnace, and I heat them
therein until they are melted into steel, when I take the melting pot out and
pour its contents into an ingot or other mould in the usual manner. But I
do not confine myself to these proportions, as they must be varied according
to the relative quantity or proportion of carbon contained in the cast iron; and
here it is to be observed that if it is required to increase the hardness of the
steel, the proportion of granulated cast iron should be increased; but if softer
steel is required, the relative quantity or proportion of the granulated cast iron
is to be diminished, the relative proportions of the other materials remaining
the same; or the hardness of the steel may be increased by diminishing the
relative proportion of deoxydized iron ore, and the steel may be made softer
by increasing the relative proportion of deoxydized iron ore in respect of the
quantity of granulated cast iron operated upon, the relative proportion of
the "spiegel eisen" remaining the same. The "spiegel eisen or triple
compound, consisting of or containing iron, carbon, and manganese, may be
introduced into the melting pots along with the mixture of granulated cast
iron and deoxydized iron ore, and melted therein, together with them, in the
manner I have herein-before described, or only a portion of the whole quantity
of the said triple compound to be employed may be thus introduced and
melted with the other materials, and a further portion of the triple compound
in a melted state may then be added to the mixture in the pots or crucibles
when the said mixture is also in the melted state, or the whole of the triple
compound of iron, carbon, and manganese intended to be employed may be
thus added in the melted state to the mixture of granulated cast iron and
deoxydized iron ore in the melting pots or crucibles after the said cast-iron
and deoxydized iron ore shall have been melted. But I generally prefer to
add about two-thirds of the requisite quantity of the compound of iron, carbon,
and manganese intended to be employed to the mixture of granulated cast
iron and deoxydized iron ore when the said mixture is charged into the
melting pots, and then to add the remainder of the requisite quantity of the
triple compound in the melted state to the mixture in the pots when the latter
is melted, stirring the mixture with a rod of iron or steel when the quantity
operated upon is large, so as to blend and combine the materials, and then
pouring the fluid molten mass into any suitable ingot mould or moulds.

page_text: When the triple compound of iron, carbon, and manganese, or any portion
of the said triple compound is to be added in the melted state to the melted
mixture of granulated cast iron and deoxydized iron ore, the triple compound
is to be melted and rendered fluid in any convenient manner, either in a
separate melting pot or crucible, or in an air furnace, or in a reverberatory
furnace, or in a common cupola furnace, or otherwise, and the requisite
quantity of it is then to be poured from a crucible or ladle into each pot or
crucible of the melted mixture of granulated cast iron and deoxydized iron ore,
either when the crucibles are in the melting furnace, or when they have been
taken out in order to pour their contents into the ingot or other moulds. In
either case the mixture is to be previously stirred up with an iron or steel rod
whenever the quantity operated upon is large, and is then to be poured into
the moulds. The contents of two or more melting pots or crucibles, each
containing a melted mixture of granulated cast iron and deoxydized iron ore
in suitable proportions for producing cast steel, may be poured into any
suitable ladle or receptacle containing a sufficient quantity of the melted triple
compound of iron, carbon, and manganese; or the melted triple compound may
be poured into such ladle or receptacle and be there mixed and stirred up
with the melted mixture of granulated cast iron and deoxydized iron ore
previously placed therein, the steel produced is then to be poured into suitable
ingot or other moulds; or, the inelted cast iron, the deoxydized iron ore, and
the triple compound, consisting of or containing iron, carbon, and manganese,
may be combined and blended together in any other convenient manner.
As a triple compound of iron, carbon, and manganese parts with a portion
of its manganese every time it is melted, I prefer to use that which has not
been previously remelted, and I avoid as much as possible any repeated
remeltings of it. The triple compound, consisting of or containing iron,
carbon, and manganese, which I prefer to use, namely, the manganesic cast
iron termed spiegel eisen, has been found to consist of metallic manganese
from two parts to eight parts by weight per centum, and of carbon from
two parts to five and a half parts by weight per centum, the residue being
iron.
Having thus particularly ascertained and described the nature of my said
Invention, and the manner in which the same is to be performed, I hereby
declare that what I claim is, the improvement or improvements in the manu-
facture of cast steel herein described, that is to say, manufacturing cast steel
by beating, melting, combining, and blending together, in melting pots or
crucibles or otherwise, the three following materials or substances, namely,

page_text: broken, crushed, or granulated cast iron, deoxydized iron ore, and a triple
compound containing iron, carbon; and manganese.
In witness whereof, I, the said Robert Mushet, have hereunto set my
hand and seal, this Third day of June, in the year of our Lord One
thousand eight hundred and fifty-nine.
Witnesses,
EDWP. M. MUSHET,
Coleford, Gloucestershire.
BROOKLYN MUSHET,
Coleford, Gloucestershire.
ROBT. MUSHET. (L.S.)