AN IMPROVEMENT OR IMPROVEMENTS IN THE PROCESS OR PROCESSES OF MAKING OR MANUFACTURING IRON
Year: 1815

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, DAVID
MUSHET, of Coleford, in the County of Gloucester, Iron Master, send greeting.
WHEREAS His present Majesty King George the Third, in and by His
Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Twenty-seventh day of July now last past, for Himself, His
heirs, and successors, did give and grant unto me, the said David Mushet,
my executors, administrators, and assigns, His especial licence, full power,
sole privilege and authority, that I, the said David Mushet, my executors,"
administrators, and assigns, and every of them, by myself and themselves, or
by my and their deputy or deputies, servants or agents, or such others as I,
the said David 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 of years therein expressed, should and lawfully
might make, use, exercise, and vend, within England, Wales, and the Town
of Berwick-upon-Tweed, my Invention of "AN IMPROVEMENT OR IMPROVEMENTS
IN THE PROCESS OR PROCESSES OF MAKING OR MANUFACTURING IRON;" in which
said Letters Patent there is contained a proviso, obliging me, the said David
Mushet, by an instrument in writing under my hand and seal, particularly to
describe and ascertain the nature of my said Invention, and in what manner
the same is to be performed, and cause the same to be inrolled in His
Majesty's High Court of Chancery within six calendar months next and
immediately after the date of the said recited Letters Patent, as in and by
the same, reference being thereunto had, will more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
David Mushet, do hereby declare that the nature of my said Invention, and
the manner in which the same is to be performed, are described and ascer-
tained as follows, that is to say:-
I have discovered a method, means, or processes, for refining pig or cast
iron in a blast furnace, to which, when used for this purpose, I give the name
of the smelting refinery. By my said Invention, the whole or greater part of
the metallic contents of the cinder, slag, or scoria produced from the common
refinery of the slags, cinder, or scoria that falls at the puddling or roughing
rollers of the slag, scoria, or cinder commonly called hammer slag,-of the slag,
scoria, or cinder that is produced from the mill, balling and puddling furnaces-
of the scale or shale that is produced at the finishing rollers-and of any other
refuse containing iron formed in any stage of the process or processes of making
or manufacturing bar or malleable iron of every description is recovered or revived,
and brought directly into the state of what is known in the trade by the name
of finers' iron, or metal of a quality fit for the purposes of the puddling fur-
nace or stamping fire; and in effecting this I make use of the superfluous carbon
or coally matter of a portion of pig or cast iron, in reviving and reducing the
iron contained in the said various slags, scoria, cinder, scale, or other refuse
products containing iron, converting at the same time the iron contained in the
pig or cast iron into finers' iron or metal; when about to work with these
materials I proceed in the following manner :-I take from three hundred to
four hundred pounds of well-burnt coke, charcoal, or other fuel alone or in
mixture, six hundred pounds of pig or cast iron reduced into any convenient
size or form, one hundred and eighty to two hundred and forty pounds of the
various slags, scoria, cinder, scale, or other refuse containing iron, or any one
or more of them; to these I add from one hundred to one hundred and fifty
pounds of limestone, or in that proportion, or from forty to one hundred and
twenty pounds of burnt lime, which last I generally prefer. These different
items I denominate a charge, which at proper intervals is filled into the furnace
or smelting refinery, previously prepared and heated for its reception, according
to the ordinary and common methods practised at ironworks. But the charge
may be increased or diminished according to circumstances, due regard being
paid to the aforesaid proportions. When the charge or charges successively
reach the hearth of the furnace, the metallic parts sink to the bottom and become
covered with the earthy matters of the charge in the state of glass or scoria;
no part of this should be allowed to flow or run off (as is now the case at blast
furnaces) till the furnace is tapped, the glass or scoria then follows the metal;
and I find it convenient and advantageous to allow it to form a covering over

page_text: the metal in the box or mould prepared for its reception. If after the first or
second tapping the metal is found not sufficiently decarbonated, or in the
language of the manufactory "not high enough blown," I gradually reduce the
proportion of coke, charcoal, or other fuel, or I keep adding from time to time
a larger quantity of the said slags, cinders, scoria, scale, or other refuse, with a
proportionate quantity of lime, till the quality of the metal is sufficiently refined
for the purposes of the puddling furnace or stamping fire. At this particular
stage the process may be deemed complete, and the whole expence for labour
and fuel will be found not materially to exceed that of the common refinery;
which operation consists chiefly in burning out a part of the carbon or coally
matter contained in the pig or cast iron, by which a loss is sustained of from
two and a half to three hundredweight in the ton. But, as in my process I
make use of this carbon to revive or reduce the iron contained in the said slags,
scoria, cinder, scale, or other refuse products of the forge, I generally obtain
after the rate of twenty-four to twenty-five hundredweight of finers' iron or
metal, for each ton of pig or cast iron introduced into the smelting refinery
furnace.
.
But, secondly, in situations where the operations of the forge are not
carried on, I make use of iron ores or ironstones, in mixture with pig or cast
iron, in any convenient shape or form, for refining or converting the metallic
contents of the same into finers' iron or metal; and my mode of operating with
these substances is similar to that above described with pig or cast iron, and
the said slags, scoria, scale, cinders, or other refuse containing iron; the
materials in their proper proportions being introduced into the smelting refinery
furnace, and the process conducted as above described. Iron ores and iron.
stones may be used for refining or decarbonating the pig or cast iron, either
raw or roasted, and the proportion of lime necessary to be added to each charge
ought to be the same as is added in the common process of pig iron making in
the blast furnace, except in cases where iron ores or ironstones are used con-
taining fifty-five per cent. or more of iron, such ores admitting of a reduction
of the quantity of lime or limestone, in proportion as the earthy matter in
them decreases.
Thirdly, the foregoing modes of manipulation are convenient in situations
where pig or cast iron is at hand, but where it may be otherwise, or it
may be wished to avoid the using of pig or cast iron, I apply my said
Invention in the following manner to revive and recover the iron contained
in the following substances, and to bring it directly into the state of refined
iron or finers' metal in the smelting refinery furnace without any mixture of
pig or cast iron, as described in the foregoing processes, that is to say:--If the

page_text: materials are slags, scoria, or cinder, of the mill, balling, or puddling furnaces,
of the puddling or roughing rollers of the blooming or stamping hammer com-
monly called hammer slag, of the common refinery furnace, or the scale that
is formed in the making, rolling, or finishing of bar or other malleable iron.
(the smelting refinery furnace being previously heated), I take from three!
hundred and fifty pounds to four hundred and fifty pounds of coke, charcoal,
or other fuel seperately, or in mixture, from three hundred to three hundred
and fifty pounds of the above-described forge refuse, from one hundred to one
hundred and twenty pounds of burnt lime, or from one hundred and forty to
one-hundred and seventy pounds of limestone, but I prefer the burnt lime.
This charge, or any other quantity similarly proportioned, I introduce from time
to time into the smelting refinery furnace, without any mixture of pig or cast
iron; when the charge reaches the hearth of the furnace, the metal falls to the
bottom covered with the earthy matters in the state of scoria or glass. This
should be carefully kept over the iron till the same is run from the furnace,
and not allowed to run off from time to time as in the common mode of pig
iron making. If, after repeated tappings, the iron is found not to be sufficiently
decarbonated or refined, a portion of the coke, charcoal, or other fuel is to be
gradually reduced from each charge, as described in the former processes, or a
larger quantity of the said slags or refuse containining iron added till the metal is:
obtained of the requisite quality. By following this mode of operation, finers'
metal or refined iron may be made from a general mixture of the slags, scoria,
'cinder, scale, or other refuse of the forge as they are produced, but it also may
'be made from any one or more of them, in any or in every proportion as to
mixture and quantity, by accommodating the proportion of lime in some!
measure according to the following scale: -Mill scale, one-sixth its weight of
'burnt lime; mill or balling furnace slag, scoria, or cinder, one-third its weight
of burnt lime; puddling furnace slag, scoria, or cinder, one-half its weight of
burnt lime; puddling or roughing rollers and hammer slag, scoria, or cinder,
'one-fourth its weight of burnt lime; finery slag, scoria, or cinder, one-fourth,
its weight of burnt lime; these proportions of burnt lime to forge slags, scoria,
cinder, or scale will generally be found to answer where a moderate combina
tion of earthy matter enters into their composition, and into that of the coke,
charcoal, or other fuel; but instances may occur where a greater or less
quantity will be necessary than that given in the above proportions.
Fourthly, where it is desireable that refiners' iron or metal, as it is called,
should be produced directly from ironstones or ores, without employing pig or cast
iron, I proceed in the following manner:-The smelting refinery being properly
prepared, I take from three hundred to four hundred pounds of coke, charcoal, or

page_text: other fuel, seperately or in mixture, from three hundred to three hundred and
fifty pounds of iron stone or iron ore, reduced to small fragments," with the
same quantity of lime by weight as would be necessary to flux the ironstone
or ore in the common smelting furnace for the production of pig or cast iron;
this or any other quantity similarly proportioned I introduce from time to time
into the smelting refinery furnace, where the same operation takes place that
has been already described; care being taken to keep the whole of the vitri-
fied matter, glass or scoria formed from the lime and earthy matters of the
ore over the fluid metal till the same is tapped out, as above described. In
this, as in the processes förmerly detailed, should the metal thus obtained
directly from the ironstone or ore be. found not sufficiently decarbonated, or
not enough blown, the proportion of coke, charcoal, or other fuel in the charge
is to be gradually reduced, or the quantity of ironstone or. ores increased till
the metal is produced of a proper quality, as before directed. When I' make
use of ironstones I prefer the same roasted, and when iron ores richer in iron
than those commonly sinelted at the iron works in this country are made use
of, no. other earthy matter is necessary, and no more time than is requisite to
unite with the earths contained in the said ores to effect a seperation of their
metallic contents. But in cases or in situations where the ironstones or ores
are already united with lime properly denominated calcareous oręs of iron
(such as are found in His Majesty's forest of Dean), instead of adding lime to
the charge of coke, charcoal, or other fuel and ironstone or iron ore, I add
clay or clay-shale in the raw or burnt state, tho' I prefer using it in the latter,
or I add argillaceous or common ironstone in quantity or quantities propor-
tioned to the calcareous earth contained in the ores, which proportions the
nature of the materials alone can determine. When I intend to smelt ores for
the production of'finers' metal or refined iron that contain fifty-five per cent. of
iron and upwards, I prefer using four hundred and fifty pounds of coke, char-
coal, or other fuel, to three hundred pounds of the ore, besides the proper
proportion of lime, clay, clay-shale, or argillaceous or common ironstone, as
the nature of the ores. may require, and should. I find the metal not sufficiently
decarbonated, I reduce the.quantity of coke, charcoal, or other fuel, or increase
the quantity of ore to each charge till the iron is produced of the 'requisite
quality.
.
Fifthly, as it may sometimes be convenient to use slags, scoria, or other
refuse containing iron, at the same time with ironstones or iron ores, it is proper
that I should mention that this may be done by any intelligent operator, either
with or without pig or cast iron, if he attends to the directions before given,
taking care to proportion the flux to the metallic and earthy contents of the

page_text: charge, and observing, as a general rule, that not only in this case, but in all
the previously described modes of using my said Invention, the metal in the
hearth of the furnace is to be protected from the injurious effects of the blast
by a large body of scoria or vitrified matter, say, to the depth of from fifteen to
eighteen inches or more before tapping. I may further remark here that, tho' I
have directed the furnace to be tapped from time to time (viz, when the metal has
reached a certain height in the hearth, beyond which the depth of the incum-
bent vitrified matter would be too much reduced), yet an intelligent operator
may work otherwise, by having a hearth of sufficient depth under the twyre,
and allowing part of the scoria to run off, but still leaving a sufficient depth
to protect the iron, by which means he will be enabled to run off a greater
quantity of metal at one tapping. In all the foregoing processes, if the just
proportion of materials is in the furnace, and the operation otherwise well con
ducted, the glass or scoria will be found of a greenish colour, possessed of some
transparency.
Sixthly, in making and manufacturing finers' metal or refined iron in the
smelting refinery furnace, by any of the methods or processes, or with any of
the substances or mixtures of them before enumerated, if I find the materials
sufficiently fusible for the purpose, I withdraw a greater quantity of the coke,
charcoal, or other fuel, from each charge than is necessary to the making of
what is commonly denominated and understood in the iron trade by the term
finers' iron or metal, or I add a greater quantity to each charge of slags, scoria,
cinder, scale, or other refuse containing iron or ironstones or iron ores, with the
proportionate quantity of lime or flux, till I obtain the degree of decarbonation
or refinement wished for; this I do to lessen the waste of the iron in the subse-
quent operations of converting it into bar or malleable iron; it being a fact
well known in the trade that the higher the iron is refined or "blown," the
less is the loss or waste sustained in the subsequent manipulations of the forge,
taking care to keep an equal or even a greater depth of glass or scoria over the
metal in the furnace, as before directed.
Seventhly, I apply my said Invention to the manufacture of pig or cast iron,
by keeping the surface of the metal in the hearth protected by a sufficient
depth of scoria or vitrified matter, and drawing off the metal from below the
same, instead of allowing it to flow off above, as in the common method of
working, and I have ascertained that the manufacture of pig or cast iron in
this manner requires a less powerful blast than is usually necessary, while at
the same time, ores of a richer quality may be used in the furnace than can be
reduced with advantage in the mode of making pig or cast iron usually followed.
may further remark that, in all the foregoing processes it is advantageous to
I

page_text: have all the materials excepting the coke, charcoal, or other fuel broken or
formed into fragments so small that the whole may pass through a sieve whose
openings do not exceed three quarters of an inch; one great aim (both as to
economy and the quality of the product) being the exposure of as much sur-
face as possible of the different materials to the mutual action of each other
and of the fuel. In the preceding description of my Invention, and the processes
by which I carry the same into effect, I have sometimes mentioned lime only
as the flux, being that which I generally prefer, though other fusible earths or
mixtures of earths or calcareous iron ores may be used, but in my opinion not
with equal advantage.
Lastly, as to the furnace proper for the foregoing processes, it is sufficient to
say that in its general form it differs not from a common blast furnace except-
ing in the shape of the hearth, which for my Invention I prefer having of a
square or a cylindric form. As to its size, I prefer one of smaller dimensions
than the common blast furnace now in use, viz., from twenty to thirty feet in
height, from six to eight feet diameter at the boshes or widest part, and from
two to three feet diameter at the top; the hearth, five or six feet high, and from
two and a half to four feet in diameter.
In witness whereof, I, the said David Mushet, have hereunto set my
hand and seal, the Twenty-fifth day of January, in the year of our
Lord One thousand eight hundred and sixteen.
DAVID (L.S.) MUSHET.
AND BE IT REMEMBERED, that on the same Twenty-fifth day of January,
in the year above mentioned, the aforesaid David Mushet came before our
5 Lord the King in His Chancery, and acknowledged the Specification afore-
said, and all and every thing therein contained, in form above written.
And also the Specification aforesaid was stamped according to the tenor of
the Statute in that case made and provided.
Inrolled the Twenty-sixth day of January, in the year above written.