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 15th September 1859, and dated the 18th March 1859.
PROVISIONAL SPECIFICATION left by the said Robert Mushet at the
Office of the Commissioners of Patents, with his Petition, on the 18th.
March 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:-
My Invention consists in manufacturing cast steel by adding an alloy of
tungsten, iron, and manganese to cast iron which has been decarbonized, or
nearly, decarbonized, whilst in a melted state, by air having been passed or
forced through it. I add the said alloy to the said cast iron, while the latter
is in a molten state, and I stir the mixture with a rod of iron or steel, so as
thoroughly to incorporate the said alloy, with the said cast iron. I prefer to melt
the said alloy, and to add it whilst in a molten state to the said cast iron. The
alloy of tungsten, iron, and manganese which I employ in carrying my Invention
into effect may be economically prepared by melting deoxydized wolfram or

page_text: tungsten, ore, or deoxydized tungstic acid or other oxyde of tungsten, with a
metallic compound of iron, and manganese containing carbon, such as the
white crystalline pig iron made in Rhenish Prussia, and called "spiegel
eisen," and which said "spiegel eisen" is an alloy or compound of iron
and manganese containing carbon. One part by weight of deoxydized wolfram
to four parts by weight of "spiegel eisen " form a suitable alloy of tungsten,
iron, and manganese for carrying my Invention into effect. But I do not
confine myself to any particular method of making the alloy of tungsten, iron,
and manganese, nor to the precise proportions of the constituents of the said
alloy. The relative proportions of the alloy of tungsten, iron, and manganese
and the decarbonized or nearly decarbonized cast iron may be varied according
to the quality of steel which it is wished to produce. The greater the relative
proportion of the said alloy to tho said decarbonized or nearly decarbonized
cast iron the harder will be the steel produced. In practice, I have found
that from two to fifteen parts by weight of the said alloy to every one hundred
parts by weight of the said decarbonized cast iron produce the several
qualities of steel required in commerce. But I do not limit myself to theso
proportions.
The essence of my Invention consists in manufacturing cast steel by the
addition of an alloy of tungsten, iron, and manganese to melted cast iron
which has been decarbonized, or nearly decarbonized, by having had air passed
or forced through it whilst in a molten state.
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 September 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
MUSHET, of Coleford, in the County of Gloucester, Metallurgist, senil
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of March, 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 1, 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, excrcise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for "Ax IM-
PROVEMENT 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 Invention consists in manufacturing cast steel by adding an alloy of
tungsten, iron, and manganese to cast iron which has been decarbonized, or
nearly decarbonized, whilst in a melted state, by air having been passed or
forced through it. I add the said alloy to the said decarbonized or nearly
decarbonized cast iron, while the latter is in a molten state, and I stir the
mixture with a rod of iron or steel, so as thoroughly to incorporate the said
alloy with the said decarbonized or nearly decarbonized cast iron. I prefer to
melt the said alloy, and to add it whilst in a molten state to the said cast iron;
but the said alloy may be added in a solid state to the said molten decarbonized
or nearly decarbonized cast iron.
The alloy of tungsten, iron, and manganese which I employ in carrying my
Invention into effect may be conveniently prepared by melting deoxidized
wolfram or tungsten ore, or deoxidized tungstic acid, or other oxide of
tungsten, with a metallic compound of iron and manganese containing carbon,
such as the white crystalline pig iron metal made in Rhenish Prussia, and
called "spiegel eisen," and which said "spiegel eisen" is an alloy or com-
pound of iron and manganese, containing also carbon. One part by weight of
deoxidized wolfram to four parts by weight of "spiegel eisen" form a suitable
alloy of tungsten, iron, and manganese for carrying my Invention into
effect.
But I do not confine myself to any particular method of making the alloy
of tungsten, iron, and manganese, nor to the precise proportions of the con-
stituents of the said alloy. The relative proportions of the alloy of tungsten,
iron, and manganese, and the decarbonized or nearly decarbonized cast iron
may be varied according to the quality of steel which it is wished to produce.

page_text: The greater the relative proportion of the said alloy to the said decarbonized
or nearly decarbonized cast iron the harder will be the steel produced. In
practice I have found that from two to fifteen parts by weight of the said
alloy to every one hundred parts by weight of the said decarbonized or nearly
decarbonized cast iron produce most of the qualities of cast steel required in
commerce. But I do not limit myself to these proportions, as the proportions
'may be varied without departing from the nature of my Invention. The cast iron
which I prefer to use is that which is prepared by smelting in a blast furnace
the purest hæmatite, spathose, magnetic, or specular iron ores, as 'free as
possible from sulphur, phosphorus, and arsenic, the 'said smelting being effected
'with wood or charcoal fuel, or with pure coal or coke fuel naturally free or
artifically freed from sulphur as much as possible.
The "spiegel eisen," or compound of iron and manganese which I prefer to
use is that which contains a large percentage of manganese, and is nearly or
wholly free from sulphur and phospliorus. "Spiegel eisen" contains, besides
iron and carbon from two to eight per centum of its weight of manganesc.
Though I find it convenient to make use of the "spiegel eisen" of Rhenish
Prussia, other "spiegel eisen," or other compounds of iron, manganese, and
'carbon may, nevertheless, be employed for my process. The wolfram ore
which I prefer to use is that which contains a large per-centage of tungsten,
and is free or nearly free from sulphur, arsenic, and gangue or vein stone.
I deoxidize the wolfram ore, and prepare it for my process in the following
'manner :-The furnace I employ for reducing or deoxidizing the wolfram is
an ordinary steel converting furnace furnished with converting chests or pots
in the usual manner; but I am careful to construct the said furnace of the
most refractory fire-stone or fire-bricks, in order to enable the said furnace to
withstand the intense heat which I apply in order to deoxidize or reduce the
wolfram. I prepare the wolfram or other tungsten mineral or compound by
breaking it, if in lumps, into pieces of the size of a walnut and under, and I
separate the broken wolfram into from three to four different sizes by means
of sieves or riddles, and which sizes I term respectively "rough," "middle-
sized," "small," and "dust ore."
On the floor of the converting chest or pot I place a layer of coarsely
pulverized charcoal or other carbonaceous matter, such, for instance, as charred
peat or lignite, about four inches in thickness, and over this a layer of "rough
ore," three inches in thickness. Upon this I lay a bed of charcoal four inches
thick, and upon this I place a layer of "middle-sized ore," three inches in
thickness; I cover this with charcoal to the thickness of four inches, and
place upon this charcoal a layer of "small ore," three inches thick, which I

page_text: then cover with a layer of charcoal, four inches thick, and place upon this
a layer of "dust ore," three inches in thickness. If the chest or pot be
not now full, I add another layer of charcoal and another layer of "middle-
sized ore," and finish the charging of the chest by covering the whole with
charcoal to the depth of four or five inches. I then construct a rough brick
arch, coated with loam, over the top layer of charcoal, and having closed the
furnace carefully, I proceed to heat it in the manner usually practised by steel
converters in converting bar iron into steel.
But it must be observed that I do not limit myself to employ merely that
degree of heat which is sufficient for converting bar iron into steel; on the
contrary, I heat the furnace to the utmost extent which the brick or stone
materials, of which the said deoxidizing furnace is constructed, can safely with-
stand, that is to say, to a temperature ranging from one hundred to one
hundred and forty degrees of Wedgewood's pyrometric scale, and which tem-
perature is to be maintained for from seventy-two to ninety-six hours,
according to the size of the deoxidizing furnace, and the quantity of wolfram
contained in it; that is to say, if the furnace contains from five to seven tons of
wolfram, it will be sufficient to continue the intense white heat for seventy-two
hours; and if the furnace contains from seven to twelve tons of wolfram, I
prefer to continue the intense heat for about ninety-six hours. I then allow
the furnace to cool down, and when cold I open it, and withdraw the
deoxidized metallized wolfram and the charcoal which remains. I crush,
stamp, or otherwise break up the cohoering lumps or masses of deoxidized
wolfram, and I then separate the charcoal from the said metallized wolfram,
by winnowing the said charcoal away from the alloy by means of a fan blast,
or other current of air directed against a falling stream of the said mixed ore
and charcoal, or the charcoal may be separated by washing it away from the
metallized wolfram with a stream of water, in which case I subsequently dry
the said metallized wolfram upon a stove. Having thus obtained deoxi-lized
wolfram, I stamp, crush, or grind the said deoxidized wolfram, and should it
contain, as is sometimes the case, quartz or other non-metallic earthy im-
purities, these may be either separated from the said compound by winnowing
it by a blast or current of air directed against a falling stream of the said
compound, or by washing it with a stream of water, and then drying the
purified metallic residuum. The wolfram ore, when thus deoxidized and
purified, is ready for my process. When the wolfram or tungsten ore, or oxide
of tungsten which I employ is in the state of powder, or in lumps of a size not
exceeding on an average the size of a large pea, I stratify the said powder or
small lumps with charcoal coarsely powdered, that is to say, I fill the

page_text: deoxidizing chambers or converting chests with alternate layers of the said
powder, or of the said small- lumps, taking care to place a layer of coarsely
. powdered charcoal, three or four inches, in thickness, upon the floor or sole of
the converting chests, and under the first layer of the tungsten compound; I
then place upon this charcoal a layer of tungsten compound from two to three
inches thick, then a layer of powdered charcoal three inches in thickness, and
"so on until the converting chests are full, when I cover the last layer of
tungsten compound with a layer of charcoal powder five to six inches in
thickness, over which I construct a rough brick arch, coated with loam, and I
then proceed to deoxidize the tungsten ore or oxide in the manner already
herein-before described. For making the alloy of tungsten, iron, and man-
ganese, I employ melting pots or crucibles and melting furnaces, such as aro
ordinarily used by steel melters.
To thirty-six pounds of "spiegel eisen," broken into pieces the size of a
hen's egg and smaller, I add nine pounds of the prepared deoxidized wolfram
or tungsten compound; I mix these substances together, and I introduce the
mixture into a melting pot or crucible placed in a melting furnace, and I
therein heat the said substances until they are melted into an alloy of tungsten,
iron, and manganese, in which melted state the said alloy is ready for being
..used in my process, as I will now proceed to describe.
Having melted a ton of such pig iron or cast iron as I have herein-before
described in an air furnace or cupola, but preferably in an air furnace, I run
it into the vessel or chamber wherein the said cast iron is to be decarbonized,
by passing air through it. The vessel or chamber may be of any usual or
convenient form, and is to be furnished with tuyeres or air passages in the s
ordinary manner as practised in decarbonizing cast iron, by forcing or passing
air through it when the said cast iron is in the melted state. I now pass or
force air throngh the melted cast iron until the said cast iron is wholly or
.nearly decarbonized. The cast iron thus decarbonized or nearly decarbonized
is now to be tapped or run off into a strongly heated ladle or furnace, and a s
quantity of the alloy of tungsten, iron, and manganese, prepared and melted
in pots or crucibles, as I have herein-before described, is to be immediately
poured into the said decarbonized or nearly decarbonized cast iron, and the
mixture having been well stirred up with a rod or rable of iron or steel, it is
converted into cast steel, which is then to be poured or run off into ingot or 8
other suitable moulds prepared to receive the said cast steel. To each ton of
the melted decarbonized or nearly decarbonized cast iron I add from forty-five
pounds to three hundred and fifteen pounds. of the melted alloy of tungsten,
iron,, and manganese, as I find that by varying the proportion of the said alloy

page_text: to that of the decarbonized or nearly decarbonized cast iron between these
ratios, most of the various qualities of cast steel required in commerce may be :
readily obtained; and it is to be observed, that the greater the relative pro-
portion or quantity of the melted alloy of tungsten, iron, and manganese
added to a given weight of decarbonized or nearly decarbonized cast iron, the
harder will be the cast steel produced by the mixture of these substances, and
by varying the relative quantity or proportion of the alloy of tungsten, iron,
and manganese, the relative quantity or proportion of the decarbonized or
nearly decarbonized cast iron remaining the same, cast steel of any required
degree of hardness or softness may be obtained.
When the vessel or chamber in which the cast iron is decarbonized or
nearly decarbonized by passing air through the said iron when in the melted
state is so arranged and constructed that the blast can be stopped or taken off.
when the cast iron has been sufficiently decarbonized, the requisite quantity of
the melted alloy of tungsten, iron, and manganese may be poured into tho
decarbonizing vessel or chamber, and be mixed therein with the decarbonized
or nearly decarbonized cast iron, and the cast steel produced by the mixture is
then to be tapped or run off into a ladle, or into ingot or other moulds prepared
to receive the said cast steel.
I do not think it necessary to describe the processes by which the "spiegel
eisen," or other compound of iron, manganese, and carbon which I employ in
carrying my Invention into effect may be manufactured, as the said "spiegel
eisen" is an article of commerce, and the other compounds of iron, manganese,
and carbon which may be used in place of the said "spiegel eisen "
made by processes well known to metallurgists, and which said processes con-
stitute no part of my Invention.
may bo
Having thus described the nature of my Invention, and the methods by
which I carry it into effect, I wish it to be understood that I do not confine
myself to the particular method of making the alloy of tungsten, iron, and
manganese which I have herein-before described, for the alloy may be prepared
in any convenient economical manner; neither do I claim the particular
methods of melting and mixing the alloy of tungsten, iron, and manganese
with the decarbonized or nearly decarbonized cast iron which I have herein-
before described, as the melting of the alloy, and its subsequent mixture with
the decarbonized or nearly decarbonized cast iron, may be effected in any
economical and convenient manner. But the essence of my Invention consists
in the improvement in the manufacturo. of cast steel herein described; that is
to say, manufacturing cast steel by the addition of an alloy of tungsten, iron,
and manganese to melted decarbonized or nearly decarbonized cast iron, the

page_text: said cast iron having been decarbonized or nearly decarbonized by having had
air passed or forced through it whilst in the melted state.
In witness whereof, I, the said Robert Mushet, have hereunto set my
hand and scal, this Ninth day of September, in the year of our Lord
One thousand eight hundred and fifty-nine.
Witnesses,
EDWP M. MUSHIET,
Coleford, Gloucestershire.
BROOKLYN MUSIET,
Coleford, Gloucestershire.
ROBT. MUSHET. (LS.)