A NEW OR IMPROVED. 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 "A NEW OR IMPROVED.
MANUFACTURE OF CAST STEEL.".
Sealed the 18th February 1859, and dated the 16th December 1858.
PROVISIONAL SPECIFICATION left by the said Robert Mushet at the
Office of the Commissioners of Patents, with his Petition, on the
16th December 1858.
.I, ROBERT MUSHET, of Coleford, in the County of Gloucester, Metallurgist,
do hereby declare the nature of the said Invention for "A NEW OR IMPROVED
MANUFACTURE OF CAST STEEL," to be as follows:-
My Invention consists in manufacturing cast steel from cast iron, which has
been wholly or nearly decarbonized by passing air through it while in a molten
state; the conversion of the said iron into cast steel being effected by melting
the same, and treating it whilst melting or when melted with a triple
compound or mixture, consisting of or containing iron, carbon, and manganese,
as herein-after explained.
In carrying my Invention into effect, I proceed as follows:-I either melt
the decarbonized or nearly decarbonized cast iron with the triple compound
separately, and mix them in a molten state; or the wholly or nearly
decarbonized iron may be melted with a portion of the triple compound,
and a further portion of the triple compound may then be added in the
molten state. The relative proportions of the wholly or nearly wholly de-

page_text: carbonized cast iron, and the triple compound vary according to the quality
of the steel it is wished to manufacture. By varying the proportion of the
triple compound between one part by weight and twenty parts by weight of
the said compound to one hundred parts by weight of the wholly or nearly
decarbonized cast iron, steel of the various degrees of hardness required in
commerce may be produced. The greater the proportion of the triple com-
pound employed, the harder will be the steel produced.
The melting of the steel may be effected in crucibles or melting pots of the
ordinary kind used by steel melters.
The essence of my Invention consists in making cast steel by melting cast
iron which has been decarbonized, or nearly decarbonized by passing air
through it when in a molten state, and adding to or melting with the said
decarbonized or nearly decarbonized cast iron a mixture or compound con-
sisting essentially of iron, carbon, and manganese. The compound of iron,
carbon, and manganese which I employ in carrying my Invention into effect
may be made by smelting or reducing iron ores containing manganese; but I
prefer to use the variety of white crystalline cast iron made in Rhenish
Prussia, and called "spiegel eisen." The said "spiegel eisen" contains from
two to eight parts by weight of manganese to every one hundred parts by
weight of iron, together with the proportions of carbon contained in cast iron;
but I do not confine myself to any particular process or method of preparing
the triple compound of iron, carbon, and manganese.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Robert Mushet in the Great Seal Patent Office on the
18th 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 Sixteenth 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, 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 there-

page_text: after 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 "A NEW OR
IMPROVED 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 cast iron, which has
been wholly or nearly decarbonized by passing air through it while in a molten
state; the conversion of the said iron into cast steel being effected by melting
the same, and treating it whilst melting or when melted with a triple compound
or mixture, consisting of or containing iron, carbon, and manganese, as herein-
after explained.
In carrying my Invention into effect I proceed as follows:-When the cast
iron to be converted into steel has been decarbonized or nearly decarbonized,
by passing air through it whilst in a melted state, I further prepare the said
decarbonized cast iron for my process, either by granulating the metal by
running it into water, or by casting it into thin plates or cakes, which may,
when cold, be either broken up or cut up when either hot or cold by means of
shears, into small pieces of a convenient size for packing into the melting pots
or crucibles herein-after described; or the decarbonized cast iron may be
reduced into small pieces or fragments by any other convenient or economical
method, such method constituting no part of my said Invention. I now take
a quantity of the decarbonized or nearly decarbonized cast iron thus prepared,.
and I introduce it along with a quantity of a triple compound, consisting of
or containing iron, carbon, and manganese, into a melting pot or crucible
placed in a suitable melting furnace, and I heat the said substances therein
until the said decarbonized cast iron and the said triple compound are melted;
the crucible is then withdrawn from the furnace, and its contents poured into
an ingot mould, so to form an ingot of cast steel, which may then be heated
and rolled, or drawn out into bars, rods, or sheets in the usual manner, or the
melted steel may be cast into any other required form. The relative -pro-

page_text: portions of the wholly or nearly decarbonized cast iron and the triple
compound of iron, carbon, and manganese which I employ vary according
to the quality of steel it is wished to manufacture. By varying the pro-
portion of the triple compound between one part by weight, and twenty
parts by weight of the said compound, to one hundred parts by weight of the
wholly or nearly decarbonized cast iron, steel of the various degrees of hard-
ness required in commerce may be produced, the greater the relative pro-
portion of the triple compound employed the harder will be the steel
produced.
:
In practice I have found the following to be useful proportions:-To
produce very soft steel, I add two pounds of the triple compound of iron,
carbon, and manganese to thirty-eight pounds of wholly or nearly decarbonized
cast iron.
. [
To obtain cast steel of a medium degree of hardness, I add four pounds of
the said triple compound to thirty-six pounds of the said decarbonized cast
iron. When a hard quality of cast steel is required, I add six pounds of the
said triple compound to thirty-four pounds of the said wholly or nearly
decarbonized cast iron; and in each case I introduce these substances into a
melting pot or crucible placed in a suitable melting furnace, and heat the said
substances therein until they are melted, and thereby converted into. steel,
when the said steel is to be poured into ingot or other moulds in the usual
manner. I also sometimes proceed as follows:-I introduce a quantity of the
wholly or nearly decarbonized cast iron prepared as I have already described
into a melting pot or crucible placed in a suitable melting furnace, and I heat
the said iron therein until it is melted. I then remove the lid or cover of the
melting pot or crucible, and having previously melted separately the requisite
quantity of the triple compound of iron, carbon, and manganese, I pour it
into the melted decarbonized cast iron contained in the melting pot or
crucible, stirring the mixture, if necessary, with an iron or steel rod, so as to
render it homogeneous, and I then pour the steel into ingot or other moulds
in the usual manner. 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 con-
taining the decarbonized iron; when the contents of the latter are nearly
melted, and after the last charge or fire of coke 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

page_text: 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 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 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.
When I wish to obtain a very soft steel, I pour two pounds of the melted
triple compound of iron, earbon, and manganese into thirty-eight pounds of
the melted decarbonized cast iron. When cast steel of a medium hardness'is
desired, I pour four pounds of the said melted triple compound into thirty-six
pounds of the melted decarbonized cast iron. And when hard cast steel is
required, I pour six pounds of the melted triple compound of iron, carbon,
and manganese into thirty-four pounds of the melted decarbonized cast iron,
and in each case I stir the mixture when necessary with a rod of iron or steel,
and then pour the cast steel into ingot or other moulds in the usual manner;
but I do not limit myself to these proportions. Sometimes I add only a
portion of the whole amount of the triple compound of iron, carbon, and
manganese to the wholly or nearly decarbonized cast iron before fusion, and I
then introduce the mixture into a melting pot or crucible placed in a suitable
melting furnace, and I heat these substances therein until they aré melted. I
then remove the lid or cover of the melting pot, and pour in the remaining
portion or quantity of the said triple compound in a melted state, in the same
manner as I have herein-before described. I then stir the mixture when
necessary with a rod of iron or steel, and afterwards pour it into ingot or other
moulds in the usual manner. In practice I find that to produce soft. cast
steel, it is sufficient to add one pound of the triple compound of iron, carbon,
and manganese to thirty-eight pounds of wholly or nearly decarbonized cast
iron when introduced into the melting pot, and I then add to this mixture
when melted a further quantity of the said triple compound in the melted state
amounting to one pound. To obtain moderately hard cast steel, I. add to
thirty-six pounds of wholly or nearly decarbonized cast iron two pounds.of.the

page_text: triple compound of iron, carbon, and manganese, and having introduced these
substances into the melting pot or crucible, I heat them therein until they are
melted, and I then pour into the melted mixture two pounds of the said triple
compound also in the melted state. When it is required to produce hard cast
steel, I add to thirty-four pounds of wholly or nearly decarbonized cast iron
three pounds of the triple compound of iron, carbon, and manganese, and
having introduced these substances into the melting pot or crucible placed in
a suitable furnace, I heat them therein until they are melted, and I then pour
into the mixture three pounds of the said triple compound also in the melted
state, and in each case I stir the mixture if necessary with a rod of iron or
steel, and I then pour the cast steel into ingot or other moulds in the usual
'manner; but I do not confine myself to the exact proportions here given, as
the proportions may be varied.
The melting pots or crucibles which I prefer to use are those of the kind
ordinarily used by steel melters, and the furnaces in which the said pots or
crucibles are placed are such as are employed by steel manufacturers wherein
they melt their steel, and which are commonly called "melting holes." The
triple compound consisting of or containing iron, carbon, and manganese, may
be made by smelting or reducing iron ores containing manganese in a blast
.furnace with charcoal or coke fuel; but I prefer to use that variety of white
.crystalline cast iron made in Rhenish Prussia from spathose iron ores, con-
taining likewise manganese and other manganesic iron ores, and which is
called "spiegel eisen," from the brilliant facets it exhibits when newly
fractured. The said "spiegel eisen" contains from two to eight parts by
weight of manganese to every one hundred parts by weight of iron, together
with the proportion of carbon contained in cast iron; but I do not confine
myself to any particular process or method of preparing the triple compound
consisting of or containing iron, carbon, and manganese, as the said compound
may be prepared in any economical manner.
The pig iron or cast iron which I prefer to select for the purpose of wholly
or nearly decarbonizing it by passing air through it whilst in a melted state,
in order to prepare the said cast iron for my process, is such pig iron as bas
been obtained by smelting or reducing with charcoal or coke fuel rich hematite,
specular, or magnetic iron ores, or spathose iron ores, or sparry carbonates of
iron, or any mixtures of these iron ores. When coke fuel is used for the
reduction of these ores, it should be as free as possible from sulphur, and the
iron ores employed should also be selected so as to be as free as possible from
sulphur and phosphorus.
Having thus described my said Invention, and the methods by which I

page_text: carry it into effect, I wish it to be understood that I do not limit myself to
the precise details herein described, as the same may be varied without
departing from the nature of my Invention; but I hereby declare that the
essence of my Invention consists in making cast steel of the various degrees
of hardness required in commerce, by melting cast iron which has been
decarbonized or nearly decarbonized by forcing air through it when in a
molten state, and adding to or melting with the said decarbonized or nearly
decarbonized cast iron a mixture or triple compound consisting essentially of
iron, carbon, and manganese; and I regulate the hardness of the cast steel to
be produced by varying the proportion of the said triple compound added to or
melted with the said decarbonized or nearly decarbonized cast iron. The
greater the relative proportion of the said triple compound employed the
harder the steel produced will be.
In witness whereof, I, the said Robert Mushet, have hereunto set my
hand and seal, this Thirtieth day of May, in the year of our Lord
One thousand eight hundred and fifty-nine.
Witnesses,
EDW M. MUSHET,
Coleford, Gloucestershire,
BROOKLYN MUSHET,
Coleford, Gloucestershire.
ROBT. MUSHET. (L.S.)