AN IMPROVEMENT 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 "AN IMPROVEMENT IN THE
MANUFACTURE OF CAST STEEL."
Sealed the 8th July 1859, and dated the 24th January 1859..
PROVISIONAL SPECIFICATION left by the said Robert Mushet at the
Office of the Commissioners of Patents, with his Petition, on the
24th January 1859.
I, ROBERT MUSHET, of Coleford, in the County of Gloucester, Metallurgist,
do hereby declare the nature of the said Invention for "AN IMPROVEMENT IN
THE MANUFACTURE OF CAST STEEL," to be as follows:-
When iron ores or oxides of iron are strongly heated in close chambers or
converting furnaces exposed to the influence or action of carbon and hydrogen
or other reducing or deoxydizing substances or agents, they are gradually
deprived of their oxygen, and are then in the state of metallic iron more or
less mixed with the silica and other earthy matters originally associated with
these iron ores or oxides of iron. If the metallic iron thus obtained by
deoxidizing these iron ores or oxides of iron is strongly heated in close
chambers or converting furnaces in contact with carbonaceous matter, the air
being carefully excluded, a portion of the carbonaceous matter is absorbed by
the metallic iron, and combines therewith, forming a kind of crude steel,
resembling the blistered steel of commerce in some respects, but not possessing
its ductility and capacity for welding.
The essence of my Invention consists in melting such crude steel as I have
described, obtained from deoxidized iron ores or oxides of iron, and combining it
during the melting or. when melted with a triple compound consisting of iron,

page_text: ores
carbon, and manganese. The said materials may be melted in melting pots or
crucibles, heated in furnaces of the kind ordinarily employed in melting steel.
The steel when melted may be cast into ingots or such other castings as may
le required. I prefer to use the purest and richest varieties of iron ore for
deoxidizing and for subsequent conversion into the crude steel, which I have
described, avoiding such iron ores as are largely contaminated with sulphur,
phosphorous, and silica. The iron ores may be deoxidized, and then converted
into crude steel in the usual manner, by heating them with charcoal or other
carbonaceous matter, in any ordinary steel converting furnace, such as is used
for obtaining blistered steel from bar iron. The triple compound of iron,
carbon, and manganese may be prepared by smelting in the blast furnace iron
which contain in addition to iron much manganese, but I prefer to
employ the white crystalline cast iron obtained in Prussia, by smelting ores of
iron containing manganese, and called "spiegel eisen," and which "spiegel
eisen" is a compound containing iron, carbon, and manganese. The pro-
portion of the triple compound of iron, carbon, and manganese which I
combine with the crude steel I have described, varies according to the nature
of the materials employed, and according to the quality of the steel which it is
intended to produce: I have found, however, in practice that it is sufficient
add from one pound by weight to five pounds by weight of the triple com-
pound of iron, carbon, and manganese to every thirty pounds by weight of
the crude steel, which I have described, obtained from deoxydized iron ore or
oxide of iron, in order to produce by melting and combining these substances
the various qualities of cast steel ordinarily required in commerce, observing
that as the proportion of the triple compound added to the crude steel is
increased, so will the hardness of the resulting cast steel be increased, and
vice versa..
In carrying my said Invention into practice, I proceed as follows:-I mix
the pieces or fragments of crude steel with the requisite proportion of the triple
compound of iron, carbon, and manganese, and I then introduce the mixture
into the melting pot or crucible, and I then proceed to melt the mixture into
cast steel, and when melted I pour it into ingot moulds in the usual manner
or I melt the crude steel by itself in a melting pot or crucible, and I melt the
triple compound of iron, carbon, and manganese in a separate melting pot oi
vessel, and when both the crude steel and the triple compound are melted and
are in a fluid state, I combine or incorporate them by pouring the contents o
the one melting pot or vessel into the other, and if necessary, in order to
accelerate the union, I stir the mixture with an iron or steel rod, and the fluid
mixture is then to be poured into ingot or other suitable moulds; or I melt a

page_text: portion of the triple compound of iron, carbon, and manganese along with the
crude steel in the melting pot or crucible, and when the mixture is melted I add
to it a further portion of the triple compound in the melted state, or the crude
steel from the deoxydized iron ore may be melted in several crucibles or
melting pots, and the contents when fluid may be poured into a suitable ladle
or receptacle, and the requisite proportion of the triple compound of iron,
carbon, and manganese may then be poured into the fluid steel, and be mixed
and combined with it.
The essence of my said Invention consists in adding to crude steel obtained
by deoxydizing, and then cementing or converting iron ore or oxide of iron
in suitable deoxydizing or cementing furnaces, a triple compound of iron,
carbon, and manganese, so as to melt, unite, and combine these materials in
melting pots or crucibles, or in any other convenient receptacles placed in
suitable furnaces, and subjected to the action of intense heat during the
process of melting to obtain or produce cast steel suited for commercial
purposes.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Robert Mushet in the Great Seal Patent Office on the
22nd 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 Twenty-fourth 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 "AN IMPROVEMENT
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 montlis 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 iron ores or oxydes of iron are strongly heated in close chambers or
converting furnaces, and exposed during the said heating to the action of
carbon or other reducing or deoxidizing substances or agents, the said iron
ores are gradually deprived of their oxgyen, and are reduced to the state of
metallic iron mixed with the silica and other earthy matters originally con-
tained in iron ores, or oxydes of iron. If the metallic iron thus obtained by
deoxidizing iron ores or oxydes of iron is strongly heated in close chambers
or converting furnaces in contact with carbonaceous matter, the air being
carefully excluded, a portion of the carbonaceous matter is absorbed by the
metallic iron, and combines therewith, forming a kind of crude steel resem-
bling the blistered steel of commerce in some respects, but not possessing its
ductility and capacity for welding.
The essence of my Invention consists in melting such crude steel as I have
described, obtained from deoxidized iron ores or oxydes of iron, and combining
it during the melting or when melted with a triple compound consisting of
iron, carbon, and manganese. By combining the said crude steel with the
said triple compound, the quality of the said steel is much improved.
The said deoxidized iron ore and triple compound may be melted in melting
pots or crucibles heated in furnaces of the kind ordinarily employed in
melting steel. The steel when melted may be cast into ingots or such other
castings as may be required. I prefer to use the purest and richest varieties of
iron ore for deoxydizing and for subsequent conversion into the crude steel
which I have described, and I avoid such iron ores as are largely contaminated
with sulphur, phosphrous, and silica. The iron ores may be deoxydized and
then converted into crude steel in the usual manner by heating them with
charcoal or other carbonaceous matter in any ordinary steel converting furnace,
such as is used for obtaining blistered steel from bar iron. The triple com-
pound of iron, carbon, and manganese may be prepared by smelting in the
blast furnace iron ores which contain, in addition to iron, much manganese;
but I prefer to employ the white crystalline cast iron obtained in Prussia, by
smelting ores of iron containing manganese, and called "spiegel eisen," and

page_text: which "spiegel eisen" is a compound containing iron, carbon, and manganese.
The relative proportion of the triple compound of iron, carbon, and man-
ganese which I combine with the crude steel I have described, varies according
to the particular nature of the materials employed, and according to the
quality of the steel which it is intended to produce; I have found in practice
that it is sufficient to add from one pound to five pounds of the triple
compound of iron, carbon, and manganese to every thirty pounds of the
crude steel which I have described, obtained from deoxydized iron ore or oxyde
of iron, in order to produce, by melting and combining these substances, the
various qualities of cast steel ordinarily required in commerce, observing that
as the relative proportion of the triple compound added to the crude steel is
increased, so will the hardness of the resulting cast steel be increased, and
the reverse.
In carrying my said Invention into practice, I proceed as follows:-I break
the crude steel into fragments, which fragments I mix with the requisite
proportion of the triple compound of iron, carbon, and manganese, and I then
introduce the mixture into the melting pot or crucible, and I proceed to
melt the mixture into cast steel, and when melted, I pour it into ingot
moulds in the usual manner; or I melt the crude steel by itself in a melting
pot or crucible, and I melt the triple compound of iron, carbon, and man-
ganese in a separate melting pot or vessel, and when both the crude steel and
the triple compound are melted, I combine or incorporate them by pouring
the contents of the one melting pot or vessel into the other, and if necessary,
in order to accelerate their union, I stir the mixture with an iron or steel
rod, and the melted steel is then to be poured into ingot or other suitable -
moulds, or I melt a portion of the triple compound of iron, carbon, and
manganese, along with the crude steel in the melting pot or crucible, and
when the mixture is melted, I add to it a further portion of the triple com-
pound in the melted state; or the crude steel from the deoxidized iron ore
may be melted in several crucibles or melting pots, and the contents when
fluid may be poured into a suitable ladle or receptacle, and the requisite
proportion of the triple compound of iron, carbon, and inanganese may then
be poured into the fluid steel, and be mixed and combined with it; I prepare
the deoxidized iron ore in the manner following:-I select the purest hematite
iron ores or the specular and magnetic iron ores, or the purest spathose iron
ores, and I deoxidize them by carbonaceous matter. In conducting the
deoxidizing process, I subject the iron ore to heat, ranging from eighty to
ninety degrees of Wedgewood's pyrometric scale, the said iron ores being
closely confined in brick or stone chambers or chests, such, for instance, as

page_text: 'those used by steel manufacturers for converting bar iron into blistered steel,
and mixed with carbonaceous matter. I continue the deoxidising process
until the whole or nearly the whole of the oxygen has been removed from the
"iron ore by the union of the said oxygen with the surrounding carbonaceous
matter. I find it convenient to break the lumps of iron ore, which are to be
deoxidized into small pieces of the size of a hen's egg and under that size, and
'I sometimes crush the iron ore to the state of gravel or powder, and mix it;
or stratify it with charcoal or other carbonaceous matter in the cementing or
deoxidizing chest or chamber. When the lumps of iron ore are deoxidized
"or nearly so, that is to say, when they are deprived or nearly deprived of all
their oxygen,
I take this deoxidized iron ore when cooled down, and subject
it to the action of stamps, rollers, edge runners, or any other suitable machinery
until it is reduced to the state of coarse gravel or powder. The quartz and
other earthy impurities which are more or less associated with nearly all ores of
iron, and which are found adhering to or inclosed in the lumps or masses of de-
oxidized iron ore are for the most part beaten or pulverized into a fine powder
during the process of crushing the deoxidised iron ore to coarse gravel or powder,
and I now winnow out or drive off the quartz and other light earthy impurities;
such as lime, clay, or silica, by letting the pulverized deoxidized iron ore fall
from a sieve or riddle in a thin stream exposed to the action of the wind, or of
artificial currents of air directed against the falling stream of pulverized
deoxidized iron ore; and I thus obtain the deoxidized iron ore in a nearly
-pure metallic state, and almost free from the earthy matters found mixed with
the iron ore, an adhering to it when deoxidized; or I remove the earthy
matters in any other convenient manner. But it is to be observed that I do
not claim as of my said Invention any method for thus winnowing or cleansing
deoxidized iron ore. I now introduce the deoxidized iron ore thus prepared
and purified, into a converting furnace, such as is ordinarily used by steel
manufacturers for converting bar iron into blistered steel. I stratify the said
deoxidized iron ore with charcoal in the said converting furnace in the manner
which is practised by steel manufacturers, in order to convert bar iron into
blister steel, that is to say, I place a layer or stratum of coarsely pulverized
charcoal upon the sole or floor of the converting chest or pot, and upon the
said layer of charcoal I place a layer of deoxidized iron ore, and over this a
second layer of charcoal, and then a second layer of deoxidized iron ore, and
so on until the converting chest or pot is completely filled with alternate layers
of the deoxidized iron ore and charcoal; I then cover the top of the cementing
chest with charcoal, which said charcoal I cover with loam, so as to exclude
the air, and I then proceed to heat the deoxidized iron ore and charcoal in

page_text: the ordinary manner, in order to convert the said deoxidized iron ore into steel.
For this purpose the heat is raised to a temperature of from eighty to one
hundred degrees of Wedgewood's pyrometric scale, and is then maintained at
or about that temperature for from forty to sixty hours, according to the size
of the converting chests or pots. The furnace which contains the converting
chests or pots is now allowed to cool down, and when cool enough it is opened
and the crude steel is taken out; this crude steel or "iron-ore steel," as I
term it, is now subjected to the action of stamps, rollers, or edge-runners; so
as to break up the agglutinated adhering masses in which it will be found;
and when thus stamped, crushed, or ground, it is purified from the charcoal
and other light impurities, by winnowing, as herein-before described, or in
any other convenient manner. The crude steel or "iron-ore steel," when thus
prepared and purified, is ready for my process.
I prepare the triple compound of iron, carbon, and manganese or "spiegel
eisen," as it is termed, 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. I break up the said compound by beating lumps of it upon
à block or plate of iron with a beavy hammer, and which operation is greatly
facilitated by previously heating the lumps of "spiegel eisen" to a red heat;
and then cooling them suddenly in water, which causes the said lumps to crack
and become full of fissures; or the "spiegel eisen" may be granulated by
melting it and running it into water; but as the "spiegel eisen" parts with a
portion of its manganese every time it is melted, I prefer to melt it or remelt
it as seldom as possible. To thirty pounds of crude steel or iron-ore steel,
prepared as I have herein-before described, I add three pounds of the triple
compound of iron, carbon, and manganese or "spiegel eisen" broken small,
and I mix these substances together, and introduce them into a melting pot or
crucible placed in a steel melting furnace, and I heat them therein until the
said substances are melted and combined. I then withdraw the melting pot
from the furnace, and pour the steel into an ingot mould, or such other mould
as may be required in the ordinary manner practised by steel melters.
It is here to be observed that by increasing the relative quantity or propor-
tion of "spiegel eisen," whilst that of the crude steel remains the same, the
hardness of the resulting cast steel will be increased; and the hardness of the
cast steel will be diminished by diminishing the relative quantity or proportion
of the "spiegel eisen" added to the crude steel whilst the quantity or propor-
tion of the said crude steel remains the same; and by increasing or diminishing
the relative quantity or proportion of the said triple compound of iron, carbon,
and manganese or "spiegel eisen," added in the melting pot or crucible to the.

page_text: said crude steel or "iron-ore steel," cast steel of the various degrees of hardness
required in commerce may be obtained. To diminish the hardness of the cast
steel thus prepared, I sometimes add to it wrought or malleable iron scraps;
these I introduce into, the melting pot or crucible along with the crude steel
and spiegel eisen," observing that the greater the relative quantity or propor-
tion of malleable scrap iron thus added to the crude steel and "spiegel eisen,"
the softer will be the cast steel produced.
In practice I add from one to ten pounds of wrought or malleable iron
scraps to thirty pounds of crude steel and three pounds of "spiegel eisen." I
do not, however, claim the addition of such wrought or malleable iron scraps
as part of my said Invention, as my said Invention may be carried into effect
without such an addition.
.
The "spiegel eisen" or triple compound consisting of or containing iron,
carbon, and manganese, may be introduced into the melting pots along with
the crude steel, and melted therein together with it in the manner 1 have
berein-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
crude steel, 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 crude steel in the melting pots or crucibles after the said crude
steel has been heated therein until it is melted and is in a liquid state; but I
generally prefer to add about two-thirds of the requisite quantity of the triple
compound of iron, carbon and manganese intended to be employed to the
mixture, when the said mixture is introduced or 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 said
mixture 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 steel into any suitable ingot or other mould or moulds. The
triple compound may be melted in any convenient manner previously to pouring
it into the melting pot; but in practice I have found it convenient to intro-
duce the requisite quantity of the triple compound intended to be added to
the charge of each melting pot into a small crucible, which small crucible I
place upon the lid or cover of the melting pot containing the crude steel, when
the contents of the latter are nearly melted, and after the last charge or fire
of cokes required for melting the steel has been put into the melting furnace,
and has burnt down so far that the lid of the melting pot is uncovered. The.

page_text: triple compound of iron, carbon, and manganese being very fusible, is soon
melted, and the crucible containing it being then lifted by a workman with a
small pair of tongs, another workman removes the lid of the melting pot, and
the first-mentioned workman then pours the contents of the small crucible
into the melting pot. Or the small crucible and the melting pot may be both
withdrawn from the melting furnace, and the contents of the former may then
be poured into the latter whilst standing on the floor of the casting shop, and
in either case, before pouring the steel into moulds, the mixture may be stirred
with a rod of iron or steel, though this is not essentially requisite unless large
quantities of steel are operated upon.
The small pots or crucibles I employ are made from the same clay mixture
as is used for making the melting pots, and the said small pots are readily
formed by being turned or fashioned by hand on a potter's wheel, after which
they are dried and annealed in the usual manner to prepare them for use.
Having thus described the nature of my Invention, and the manner in
which it may be carried into effect, I hereby declare that I wish it to be
understood that the essence of my Invention consists in adding together,
melting and combining in melting pots or crucibles the following substances:-
First, crude steel, which 1 term "iron-ore steel," obtained from iron ores
or oxydes of iron first deoxydized or deprived of their oxygen by cementation
with carbonaceous matter, and then converted into steel by a further cementation
in contact with carbonaceous matter.
Second, a triple compound consisting essentially of iron, carbon, and man-
ganese, such as the "spiegel eisen" of Rhenish Prussia, in order, by the union
of the said crude steel and the said triple compound of iron, carbon, and
manganese, to produce cast steel of an improved quality.
In witness whereof, I, the said Robert Mushet, have hereunto set my
hand and seal, this Twenty-fifth day of June, in the year of our
Lord One thousand eight hundred and fifty-nine.
Witnesses,
EDWARD M. MUSHET,
Coleford, Gloucestershire.
BROOKLYN MUSHET,
Coleford, Gloucestershire.
ROBT. MUSHET. (L.S.)