AN IMPROVEMENT OR. 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 "AN IMPROVEMENT OR.
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 the said Invention for "AN IMPROVEMENT. OR
IMPROVEMENTS IN THE MANUFACTURE OF CAST STEEL," to be as follows:-
My Invention consists in manufacturing cast steel from mixtures of the
following materials melted and combined together in melting pots or crucibles"
placed in ordinary furnaces for melting cast steel, the said materials being used
either with or without the addition of charcoal or other carbonaceous matters
thereto. The said materials are,-
1st, cast iron which has been partially or wholly decarbonized by passing air
amongst its particles whilst in a liquid or molten state.
2nd, deoxydized iron ore prepared by heating iron ores or oxides of iron
in close chambers or vessels in contact with charcoal or other carbonaceous
substances, or such gases as have the power of reducing heated oxide of iron
to the metallic state, such as hydrogen and gaseous or volatile hydrocarbons.
3rd, a triple compound, consisting of or containing iron, carbon, and manga-

page_text: nese, such as the white crystalline pig or cast iron metal smelted from spathose
or sparry carbonates of iron and other ores of iron, containing besides iron
much oxide of manganese. This compound is known in Rhenish Prussia as
spiegel eisen," that is to say, "looking-glass iron," from the large and brilliant
facets exhibited by its fractured surfaces, and it is found to contain from one
to eight per centum by weight of metallic manganese, and from two to five per
centum by weight of carbon, in combination with the iron. But the triple
compound of iron, carbon, and manganese, may nevertheless be prepared in
any other convenient and economical manner.
The relative proportions of these materials to be combined to produce cast
steel vary with the particular nature of the said materials, but I have found
that equal parts of partially decarbonized cast iron, and of deoxidized iron ore
combined with from three to fifteen per centum of their joint weight of the triple
compound of iron, carbon, and manganese, will produce all the qualities of cast
steel ordinarily required in commerce, and that when the cast iron. has been
wholly decarbonized, the same proportions will afford the like or similar
results, by adding to the mixture when charged into the melting pot or crucible
from one to five parts by weight of charcoal to every one hundred parts by
weight of the mixture to be operated upon.
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 Letter's
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

page_text: for "AN IMPROVEMENT 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
performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say:-
My Invention consists in manufacturing cast steel from mixtures of the
following materials melted and combined together in melting pots or crucibles,,
placed in furnaces, such as ordinarily employed for melting cast steel, the.
said materials being used either with or without the addition of charcoal
or other, carbonaceous matter thereto. The said materials are,-
1st, cast iron which has been partially or wholly decarbonized by air having.
been passed through it whilst in a liquid or molten state..
2nd, deoxydized iron ore; prepared by heating iron ores or oxides of iron in
close chambers or vessels. in contact with charcoal or other carbonaceous.
substances, or in an atmosphere of such gases as have the power of reducing
heated oxyde of iron to the metallic state, such as hydrogen and gaseous or
volatile bydrocarbons.
3rd, a triple compound, consisting of or containing iron, carbon, and
manganese, such as the white crystalline pig or cast iron metal smelted from
spathose or sparry carbonates of iron and other ores of iron, containing besides
iron much oxyde of manganese. This compound is known in Rhenish Prussia
as "spiegel eisen," that is to say, "looking-glass iron," from the large and
brilliant facets exhibited by its fractured surfaces, and it is found to contain.
from one to eight per centum by weight of metallic manganese, and from two.
to five and a half per centum by weight of carbon in combination with the
iron. But the triple compound of iron, carbon, and manganese may be
prepared in any other convenient and economical manner.
The relative proportions of these materials to be combined to produce cast
steel vary with the particular nature of the said materials, but I have found
that equal parts by weight of partially decarbonized cast iron and of deoxydized
iron ore combined with from three to fifteen per centum of their joint weight
of the triple compound of iron, carbon, and inanganese, will produce the

page_text: different qualities of cast steel required in commerce, and that when the cast
iron has been wholly decarbonized the same proportions will afford the like or.
similar results by adding to the mixture when charged into the melting pot or
crucible from one to five parts by weight of charcoal to every one hundred
parts by weight of the mixture to be operated upon.
The cast iron wholly or partially decarbonized by passing air through it
whilst in a liquid or molten state which I use is prepared for my process by
running it when liquid into water, and thereby granulating it; or it may be.
cast into thin sheets or plates, which when cold are broken or cut up with
shears or otherwise into small pieces of a convenient. size. (that is to say, from:
the size of a walnut downwards,) for packing into the melting pots or crucibles
herein-after described, or the said wholly or partially decarbonized cast iron
may be reduced to the granular state or broken up into small fragiments by any
convenient method; I do not, however, claim any such method as of my said.
Invention. The cast iron intended to be wholly or partially decarbonized for
my process by passing air through it when in the liquid or molten state should
be of the best quality, and free, or as nearly as possible free, from sulphur and
phosphorous; and the quality of such cast iron which I prefer to employ is
that grey variety commercially known as No. 1 pig iron or melting iron, but
grey cast iron known commercially as No. 2, No. 3, and bright grey pig iron
may also be advantageously employed, provided that they are free or nearly
free from sulphur and phosphorous, but I carefully avoid the use of cinder pig
iron, common white pig-iron, and all pig or cast iron containing much
sulphur or phosphorous. Cast iron wholly decarbonized by passing air
through it while in a liquid or molten state is a species of malleable or semi-
malleable iron, which does not harden when plunged into cold water at a
red heat; and the partially decarbonized cast iron which I use is cast iron so
far decarbonized as to have become steel, that is to say, it consists essentially
of iron combined with that proportion of carbon which constitutes with the
said iron steel, and which, when heated to a red heat and then suddenly
quenched in cold water, becomes hard and brittle. When broken up or
reduced to the granular state, as I have herein-before described, the decar-
bonized or nearly decarbonized cast iron is ready for my process. I prepare
the deoxydized iron ore for my purpose in the following manner :-I select the
purest hematite iron ores, or the specular and magnetic iron ores, or the
purest spathose iron ores, and I deoxydize them by carbonaceous matter, by
subjecting them, in contact with the said carbonaceous matter, to a heat ranging
from 80 to 90 degrees of Wedgewood's pyrometric scale, the said iron ore
and carbonaceous matters being closely confined in a brick or stone chamber

page_text: or chest, such, for example, as those used for converting bar iron into blistered
steel. I continue the deoxydizing 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. But it is not necessary,
and it is not desirable, to prolong this process after the removal of the oxygen
from the iron ore has been effected, so as to cause the deoxydized iron ore to
take up or combine with carbon.
I find it convenient to break the lumps of iron ore which are to be
deoxydized 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 deoxydizing chest or chamber.
When the lumps of iron ore are deoxydized or nearly so, that is to say,
when they are deprived or nearly deprived of all their oxygen, I take this
deoxydized 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 enclosed in the lumps or masses of deoxydized iron ore,
are for the most part beaten and pulverized into a fine powder during the
process of crushing the deoxydized iron ore to coarse gravel or powder, and
I winnow out or drive off the said quartz and other light earthy impuritics,
such as lime, clay, or silica, by letting the pulverized deoxydized 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 deoxydized iron ore in a nearly
pure metallic state, and almost free from the earthy matters found mixed with
the iron ore, and adhering to it when deoxydized. 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 cleaning
deoxydized iron ores; neither do I claim as of my said Invention any method
or process for deoxydizing iron ores, which deoxydation may be effected in any
convenient manner.
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 a block or plate of iron with a heavy hammer, and which operation
is greatly facilitated by previously heating the lumps of " spiegel eisen
tor a
"

page_text: 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 said "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. The melting pots or crucibles
which I use, and the melting furnaces in which they are placed for the purpose
of.melting the steel, are those ordinarily used by manufacturers of cast steel.
I will now describe the proportions of the several purified or prepared
materials which I prefer to employ, and the manner in which I prefer to mix
and combine the same in practising my Invention. To about fifteen pounds
of partially decarbonized cast iron prepared as I have herein-before described,
I add about fifteen pounds of prepared deoxydized iron ore, and about four
pounds of the prepared triple compound of iron, carbon, and manganese. These
materials I mix together, and I then introduce or charge them into a melting
pot or crucible placed in a steel melting furnace, and I heat them therein until
the said materials are melted and converted into steel; I then withdraw the
melting pot from the furnace, and pour the steel into an ingot mould or other
mould; but I do not confine or limit myself to these proportions, which must
be varied according to the relative quantity of carbon contained in the partially
decarbonized cast iron, and according to the degree or extent of the deoxy-
dation which the deoxydized iron ore has previously undergone, and which is
readily ascertained by testing the lumps of deoxidized ore with a common file.
If they file hard and brightly metallic, they are fully deoxidized; if they file
soft and dull, they are only partially deoxydized; and here it is to be observed
that if it is required to increase the hardness of the steel, the relative quantity
or proportion of the partially decarbonized cast iron should be increased, the
relative quantities or proportions of the other materials remaining the same;
but if softer steel is required, the relative quantity or proportion of partially
decarbonized cast iron is to be diminished; the relative quantities or proportions
of the other materials remaining the same; or the hardness of the steel may
be increased by diminishing the relative proportion or quantity of deoxydized
iron ore, the relative quantities of the partially decarbonized cast iron and
of the triple compound remaining in each case the same; or the hardness
of the steel may be increased by augmenting the relative quantity or
proportion of the triple compound or spiegel eisen" in the mixture; or
the steel may be made softer by lessening the relative quantity or proportion
of the said triple compound in the mixture; the relative quantities or pro-
portions of the other materials, namely, the partially decarbonized cast
iron and the deoxydized iron ore remaining in each case the same, By
65

page_text: thus varying the relative proportions of the decarbonized cast iron, the
deoxydized iron ore, or the triple compound of iron, carbon, and manganese,
all the qualities of cast steel required in commerce may be readily obtained.
When the cast-iron has been wholly decarbonized by passing air through
it I take about fifteen pounds of it prepared as herein-before described, and
I add to it about fifteen pounds of the prepared deoxydized iron ore, and
four pounds of the triple compound of iron, carbon, and manganese. To these
substances I add about eight ounces of charcoal (preferably oak charcoal),
broken or crushed into the state of a coarse powder, and I mix the said
materials together, and introduce them into a melting pot or crucible placed
in a steel melting furnace, and I heat them therein until the said materials
are melted and converted into steel. I then withdraw the melting pot from the
furnace, and pour the steel into an ingot mould or such other mould as it
may be required to use; but I do not confine myself to these proportions as
the proportions must be varied according to the varying nature of the several
materials, and the quality of the steel it is intended to produce; but it is to be
observed that the hardness of the steel is increased by increasing the relative
quantity or proportion of the charcoal added to the mixture, whilst the relative
quantities or proportions of the other materials remain the same; and the
steel may be made softer by diminishing the relative quantity or proportion of
the charcoal added to the mixture, whilst the relative quantities or propor-
tions of the other materials, namely, the decarbonized cast iron, the deoxydized
iron ore, and the triple compound of iron, carbon, and manganese remain the
same. By thus increasing or diminishing the relative proportion of the char-
coal added to the other materials, all the qualities of cast steel required in
commerce may be readily obtained. 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 the partially decarbonized cast, iron and
the deoxydized iron ore, or of the wholly decarbonized cast iron, the-de-
oxydized iron ore and the charcoal in the melting pots or crucibles, after the
said substances have been heated therein, until they are melted and are

page_text: in a liquid state.
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, 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 fluid molten mass 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 introduce 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 wholly or partially decarbonized cast iron and the
deoxydized iron ore, 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 triple compound of iron, carbon, and man-
ganese 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 re-
moves 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 withdrawn together 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. In the description herein-before given of my Invention, I have described
the actual quantities of the respective. materials which in practice I find it
convenient to employ, but any other actual quantities may be employed in
place of those I have described with the same or nearly the same effect, so
long as the relative proportions I have described. are. preserved between the
several materials.
Having thus described the nature of my Invention, and the manner in
which it is to be carried into effect, I wish it to be understood that what I

page_text: claim as my Invention is the improvement or improvements in the manufacture
of cast steel herein-before described, that is to say, the manufacturing of cast
steel from mixtures of the following materials, melted and combined together
in melting pots or crucibles, the said materials being used either with or
without the addition of charcoal or other carbonaceous matter:-
First, cast iron which has been wholly or partially decarbonized by air
having been passed through it whilst in a melted state.
Second, deoxydized iron ore.
Third, a triple compound of iron, carbon, and manganese, such as the
spiegel eisen" produced in Rhenish Prussia.
In witness whereof, I, the said Robert Mushet, have hereunto set my
hand and seal, this Ninth 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.)