IMPROVEMENTS IN THE MANUFACTURE OF STEEL, AND IN THE FURNACES EMPLOYED IN SUCH MANU- FACTURE
Year: 1858

page_text: LETTERS PATENT to James Spence, of Liverpool, in the County of
Lancaster, Iron Merchant, for the Invention of "IMPROVEMENTS IN THE
MANUFACTURE OF STEEL, AND IN THE FURNACES EMPLOYED IN SUCH MANU-
FACTURE."
Sealed the 7th December 1858, and dated the 22nd September 1858.
PROVISIONAL SPECIFICATION left by the said James Spence at the
Office of the Commissioners of Patents, with his Petition, on the
22nd September 1858.
I, JAMES SPENCE, of Liverpool, in the County of Lancaster, Iron Merchant,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN THE
MANUFACTURE OF STEEL AND IN THE FURNACES EMPLOYED IN SUCH MANUFACTURE,"
to be as follows:-
This Invention relates to the manufacture of steel from pig iron in the
puddling furnace. Steel has heretofore been made in the puddling furnace by
the use of manganese and other substances, together with a reduction of
temperature at a later stage. This reduction has been effected by introducing
fresh "slags" or pig iron, and by closing the damper. The result is thus
dependant on the discretion of the puddler, and is greatly defective in
uniformity.
This Invention is intended to produce from the puddling furnace steel in
place of iron without the use of any secondary substance or reduction of
temperature by regulating the chemical constituents or quality of the air
passed into the furnace.

page_text: Ordinary pig iron contains about twice the proportion of carbon required in
steel, common iron merely a trace. The object in steel puddling is first to
decarbonize the iron down to the limit of steel, and upon reaching it
strenuously to avoid further decarbonization, for if it occur the product is iron.
My method of effecting this is as follows:-I first analyse the pig iron or
metal to be used, and select such for the purpose as contains a full proportion
of combined carbon. I take a puddling furnace and remove or discard the
damper, which now regulates its temperature. It is not essential to alter the
body of the furnace, but I prefer to make it about six inches narrower, and
about fifteen inches longer than usual, adding the fifteen inches between the
working door and the bridge. The grate or fire I divide into two parts. The
outer or front grate (about two feet in length) I leave open below, as at
present, but I lower the level of this grate about four inches. The inner or
back grate (also about two feet long) I place about three inches above the
old level, so that it will stand about seven inches higher than the front one.
The under space or ash-pit of the back grate I enclose completely, and place
a door in the bottom. It will be seen that when this door is closed the supply
of air will be confined to the front grate, and from it will have to pass over
the burning fuel of the back grate, and so lose the remainder of its oxygen by
this second combustion before it reaches the metal. I effect this object also
without separate grates by one long grate, the further half of which is enclosed
below or by raising up to the further half a plate, upon which grate bars are
fixed so as to fill the insterstices in the bars above, and thus exclude the
passage of air, but of these I prefer the foregoing method of two grates at
different levels.
The bridge of the present puddling furnace is a low wall of fire brick. In
place of the upper course of bricks I fix a tube of refractory clay or other such
material closed at one end, and connected at the other with a pipe supplying
hot pure air under pressure. In the side of this tube next to the metal I
make a longitudinal opening, through which such hot air passes directly upon
the metal; such air may be supplied at the end of the furnace above the grate
or through the side, but I prefer the bridge, as its greater efficiency more
than compensates for the wear of the tube.
It will be seen that I can thus supply into the furnace at will either air
containing its full proportion of oxygen, or air from which the oxygen has
been removed by a second combustion, and which is, therefore, mainly inert
nitrogen and carbonic acid. I proceed to charge a furnace so constructed
with the pig iron or metal. As soon as it melts (both grates being open) I
also turn on the supply of hot air, and so give an ample supply of oxygen to

page_text: combine with and remove the excess of carbon. I thus proceed puddling or
working the metal to and fro as usual, to expose it thoroughly to the air. At
this stage I watch carefully for the first manifestations of grains, or solidifying
in the metal, which indicate that it has passed from the condition of cast iron
into that of steel. Immediately upon this I shut off the air supply or hot
blast, and close the second grate, so that no further air shall reach the metal
containing oxygen, the air which passes through the first grate being de-
oxygenated by passing over the second grate. I maintain the heat as high
and uniform throughout as possible, collect the metal into balls, and pass them
to the hammer, as usual.
It will be found that great advantage arises from this method of working
steel, inasmuch as it substitutes mechanical contrivances for the uncertain
skill of the puddler, largely reduces the difficulty of the manufacture, and
brings out an uniform product.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said James Spence in the Great Seal Patent Office on the 22nd
March 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
SPENCE, of Liverpool, in the County of Lancaster, Iron Merchant, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-second day of September, 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 James Spence, Her special licence that I, the said James Spence, my
exccutors, administrators, and assigns, or such others as I, the said James
Spence, 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 "IMPROVEMENTS IN THE
MANUFACTURE OF STEEL, AND IN THE FURNACES EMPLOYED IN SUCH MANUFACTURE,"
upon the condition (amongst others) that I, the said James Spence, my execu-
tors 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;

page_text: 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 James Spence, do hereby declare the
nature of my 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 in writing, and on reference to the accompanying Drawings, that
is to say:
My Invention of "Improvements in the Manufacture of Steel, and in the
Furnaces employed in such Manufacture," consists, firstly, in producing steel
from pig iron or other cast iron in a puddling furnace, by regulating the
quality or chemical condition of the air (passed into the furnace) by the means
hereafter described; and, secondly, in an improvement in the puddling furnace
whereby such regulation is effected.
Ordinary pig iron, or other cast iron, contains an excess of carbon, whilst
common wrought iron contains merely a trace of the same. As steel contains
an intermediate amount of carbon, the object in steel puddling is to decarbonize
the pig or cast iron down to the limit of steel, and upon reaching that limit
strenuously to avoid further decarbonization, otherwise the product will be
converted more or less into wrought iron. Now, as the principal agent in the
process of decarbonization is the oxygen contained in the air passing into and
through the furnace, (which having a chemical affinity for the carbon combines
therewith, and removes it in a gaseous form,) it follows that in the first stage
of this process a full supply of oxygen is required, and that in the second
stage none should reach the metal. In other words, in steel puddling the
first stage requires heat with oxygen, and the second heat without oxygen.
To effect objects thus differing and opposed, requires an apparatus having
different modes of action. The common puddling furnace hitherto used in
this manufacture has only one mode of action, and in consequence steel has
been made therein with difficulty and uncertainty by the aid of large quantities
of cinder or other materials, and by the closing of the damper at the latter
stage of the process, and thus the uniformity of the product depended greatly
on the judgment and dexterity of the puddler, and moreover, the closing of the
damper caused a reduction of the temperature, which had an injurious effect
upon the working of the metal in the after processes of collecting, welding, and
.balling.
In order to obviate these difficulties and to obtain a more uniform product,
I construct and work the puddling furnace in the following manner :-I build
my puddling furnace with two grates (one behind the other), divided by a

page_text: bridge, the ash-pit of each grate being entirely enclosed, and having a door or
doors in the front or side. The grates being both of the same length (about
three feet three inches), I prefer to make the inner one about two feet four
inches in width, and the outer or end grate about one foot nine inches in
width. I also place the fire-bars of the first or outer grate about four inches
below the level of the bars of the second or inner grate. It will be seen that
by this arrangement when the door of the inner or second grate is closed, no
air can pass through that fire, whilst the air which has escaped combustion in
passing through the first or outer grate before it can reach the metal must
pass over the incandescent fuel on the second or inner grate, and will be
thereby deprived of its remaining oxygen.
The fire bridge of the ordinary puddling furnace is a low wall of fire bricks
extending across the furnace behind the grate. The first bridge, or that
which divides the two grates, I construct in the ordinary manner, but the
second or that which divides the inner grate from the sole of the furnace, I
construct as follows:--Instead of the upper course of bricks I fix a Q-shaped
tube of refactory clay, closed at one end and connected at the other with a
supply of air which may be given under pressure. The side of this tube next
to the metal is furnished with a longitudinal opening, through which such air
will pass directly on to the metal.
In order more clearly to illustrate this part of my Invention and to describe
the same more in detail, I have annexed hereunto a Sheet of Drawings, and
have marked the same with figures and letters of reference corresponding with
those in the following explanation thereof.
Figure 1 represents a longitudinal section of a puddling furnace constructed
according to the principles of my Invention, and Figure 2 is a horizontal
section of the same.
A, A, are the exterior walls of the furnace; E, E, the dome; C, C, the
sole, and D, D, the chimney. E is the first or outer grate with its ash-pit F,
which is enclosed on all sides and furnished with a door or doors; and G is
the second or inner grate with its respective ash-pit I, also enclosed and
furnished with a door or doors; J is the first bridge which divides the two
grates; and K is the second bridge, the upper course of which is formed of a
tube of refractory clay L, L, closed at one end (see also detached view) the
inner side of which or that next the sole of the furnace is furnished with
a narrow longitudinal opening M, M; N is a pipe in connection with a
supply of air.
In operating with this furnace, I proceed to charge it with about four
hundred and eighty pounds of pig iron or cast iron. Whilst this is melting I

page_text: keep the doors of both the ash-pits F and H open, or mainly open, in order to
bring both fires into a state of activity. As soon as the iron is melted, the
object is to remove the excess of carbon, and in order to effect this, I close the
door of the outer ash-pit F, and keep that of the inner ash-pit H. quite open,
and also admit the supply of air through the hollow bridge L, on to the
surface of the metal. I puddle or work the fluid metal in the usual manner;
thoroughly exposing every portion of it to the decarbonizing action of the
oxygen. When the metal begins to solidify (technically called "coming to
nature") the carbon is reduced to the proportion constituting steel, and as steel
is.less fusible than cast iron, it passes from the fluid to the solid state. The
commencement of this transition is indicated by the appearance of grains
above the fluid surface. On observing these grains, I shut off the supply of
air through the hollow bridge L, open the door of the outer ash-pit F, and
close the door of the inner ash-pit H. This being done, the necessary heat is
maintained by the outer fire for the further work of collecting, welding, and
balling the metal, whilst the air which may have passed unconsumed
through that fire, having to traverse over the incandescent fuel on the inner
grate, is thereby deprived of the remainder of its oxygen, and rendered inert.
It will be found that great advantage arises from the use of this method, as it
substitutes mechanical contrivance for the very uncertain skill of the puddler,
and thus greatly reduces the difficulty and uncertainty of the manufacture.
When the balls are formed they are taken to the hammer, and worked out
as usual.
In place of making the outer grate to draw or open to the front, it may be
built to open at the end, to suit the convenience of the works.. It is also not
absolutely essential to enclose the ash-pit of this fire, but in practice I find it
desirable, as it gives a more perfect control over the process.
The complete
enclosure of the inner ash-pit, as described, is absolutely necessary, and forms
an essential feature of
my Invention.
The dimensions above given for the grates are those which I prefer, but
they should be regulated to suit the particular description of coal used as fuel.
When steel of a full degree of hardness is required, I find it expedient to use
but one sort of iron, and I prefer that made from the hematite ore, or that
of the forest of Dean; but when a soft steel is desired, I find it preferable to
work a mixture of different sorts of iron.
It is the common practice to introduce fluxes or salts into the furnace to
assist in this manufacture, but their use is not absolutely necessary or essential
to the production of steel in the furnace described, and their benefit is more
or less uncertain and contingent on their equal and thorough diffusion through-

page_text: out the entire mass. When this equal diffusion can be depended upon, the
puddler may use as a flux an alkaline base, which will unite with and abstract
the impurities of the iron. If the quality of the steel to be produced be the first
consideration, I prefer to employ the muriate of ammonia as a flux which I
consider the best, the next best being the sesquicarbonate of soda; but when
economy of cost is the leading consideration, the chloride of sodium (common
salt) may be used with some advantage.
The precise flux to be used beneficially can only be determined by the
character and quality of the particular kind of iron or mixture of iron with
which it is to be employed, as no two kinds of iron contain exactly the same
impurities. In all cases the flux should be reduced to a fine powder, and be
introduced into the furnace, and thoroughly incorporated and diffused through-
out the mass of metal at the commencement of the boil.
66
Having now described the nature and object of my said Invention of
Improvements in the Manufacture of Steel and in the Furnaces employed
in such Manufacture," together with the manner of carrying the same into
practical effect, I desire to state that I do not claim the admission of air into
the furnace by the aforesaid tube or hollow bridge, or otherwise, nor do I
claim the use of the alkaline fluxes above mentioned, as I hold the same not
to be essential, but only auxiliary to the process; but what I claim as
my Invention is,―
Firstly, the manufacture of steel from pig iron, or other cast iron in the
puddling furnace, by regulating the quality or chemical condition of the air
passed into such furnace by means of two fires (or a double fire) acting as
above described.
And, secondly, the improvement in the construction of the puddling furnace,
above set forth and shown in the Drawings, whereby such regulation is
effected; or any mere modification thereof by which the same end may be
attained.
In witness whereof, I, the said James Spence, have hereunto set my
hand and seal, this Seventeenth day of March, in the year of our
Lord One thousand eight hundred and fifty-nine.
JAMES SPENCE. (L.S.)