AN IMPROVE- MENT IN THE PROCESS OF PUDDLING IRON
Year: 1854

page_text: LETTERS PATENT to James Nasmyth, of Patricroft, near Manchester, in
the County of Lancaster, Engineer, for the Invention of "AN IMPROVE-
MENT IN THE PROCESS OF PUDDLING IRON."
Sealed the 21st July 1854, and dated the 4th May 1'854.
PROVISIONAL SPECIFICATION left by the said James Nasmyth at the
Office of the Commissioners of Patents, with his Petition, on the 4th
May 1854.
I, JAMES NASMYTHI, of Patricroft, near Manchester, in the County of Lan-
caster, Engineer, do hereby declare the nature of the said Invention for "AN
IMPROVEMENT IN THE PROCESS OF PUDDLING IRON " to be as follows:-
The Invention relates to an improvement in the process of puddling or
refining iron, whereby the molten iron in the puddling furnace is subjected to
violent agitation, and the removal of the carbon from the metal as well as the
sulphur and other impurities is greatly expedited. These results I obtain by
the injection of steam or water beneath the surface of the molten metal, tho
heat of which resolves the steam or water (immediately it comes in contact
with the metal) into its elements, and a slight explosion of the gases ensues,
sufficient to upheave the metal and disturb its surface. This action will
continue so long as the steam or water is supplied to the molten metal. The
steam or water may be introduced from a boiler or cistern to the furnace by
means of a pipe bent into the form of a rake or puddling rod, and capable of
being worked like the ordinary puddling rod by the attendant, or, if required,
by mechanical means.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said James Nasmyth in the Great Seal Patent Office on the
3rd November 1854.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
NASMYTH, of, Patricroft, near Manchester, in the County of Lancaster, En-
gineer, send greeting.
1
- f
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourth day of May, in the year of ouf Lord One
thousand eight hundred and fifty-four, in the seventeenth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the
said James Nasmyth, Her special licence that I, the said James Nasmyth, my
executors, administrators, and assigns, or such others as I, the said James
Nasmyth, my executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at, all times hereafter 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 "AN IMPROVEMENT IN THE PROCESS
OF PUDDLING IRON," upon the condition (amongst others) that I, the said
James Nasmyth, by an instrument in writing under my hand and seal; 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 James Nasmyth, do hereby declare the
nature of my said Inventiou, and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement,
reference being had to the Drawing hereunto annexed, and to the letters and
figures marked thereon (that is to say) :-
I
7.
In order that the nature of my Invention may be more clearly understood,
-it-may-be-well-to-explain the object and present mode of effecting the opera-
tion which in the manufacture of iron is termed "puddling." With this view
may premise that cast iron owes its distinctive properties from wrought iron
chiefly to the presence of carbon existing in combination in some peculiar
condition with the iron. It also contains silex, sulphur, and other impurities,
from which wrought iron is in great degree free. To convert cast iron into
wrought iron it is requisite to free the iron more or less from the carbon which
it contains, and in doing so it is also desirable to drive off the other impurities
combined or mixed with the iron.
One process by which this object is

page_text: accomplished is termed "puddling." It consists, in the first place, in raking
backwards and forwards molten cast, iron in a furnace, the tool or instrument
employed to effect the raking being called a "rabble." This raking back-
wards and forwards of the molten cast iron puts it into a state of agitation,
and thus successively exposes fresh-surfaces of the molten metal to the action
of. a current of atmospheric air, which the draft of the furnace carries over
its surface. The carbon of the cast iron thus becomes oxidated, and passes
off in the condition of carbonic acid and carbonic oxide. On the continuance
of this agitating action for a sufficient length of time, the cast iron begins to
lose its fluidity to a certain extent and becomes thick and pasty, shortly after
which granulated particles of wrought or malleable iron appear in the scoria.
These particles, which the puddling and decarbonizing process just described
has converted, are afterwards formed into balls and brought out of the furnace,
to be hammered or squeezed into blooms or bars in the usual way. The
object, therefore, of the process termed "puddling" is to remove the carbon
from cast iron, and so convert it into. malleable, or wrought iron; and, as is well
known, the operation. is a very labórious one, requiring long and violent manual
exertion with little intermission. It will therefore be evident that if with due
economy the oxidation of the carbon of the molten iron can be expedited
without injury to the quality of the wrought iron resulting from the operation,
an important improvement, will be effected in the puddling of iron. Now, my
Invention relates to a process of puddling iron, whereby not only will the
disengagement of the. carbon from the molten metal be greatly expedited, but
the quality of the iron will also be considerably improved. In carrying out
this Invention I subject the molten cast iron in the puddling or refining
furnace to the action of a current or currents of steam, introduced as nearly
as practicable to the lowest portion of the molten iron; and thence diffused
upwards, so as not only mechanically to agitate the molten iron, and thereby
keep exposing fresh surfaces of the iron to the oxygen contained in the
atmosphere passing through the furnace, but alsó, when brought into contact
with the incandescent iron, to be reduced to its elements and yield oxygen,
which will chemically combine with the carbon. of the iron as well as with the
sulphur or other oxidizable substances of the iron with which it may come
into contact and have affinity, and thereby deprive the iron of those impurities,
whilst the other component of the steam simultaneously liberated; namely,
hydrogen, is free to combine with any sulphur present in the furnace, whether
as.an.ingredient in the iron or as a product of combustion of the fuel employed
for heating the iron, and thus substances very prejudicial to the quality of
the iron will be removed or prevented from combining therewith, whilst at

page_text: the same time the operation will be materially expedited. To illustrate a
mode of carrying my Invention into effect, I have appended the accom-
panying Drawing. Fig. 1 is a cross section of an ordinary puddling fur-
nace, suitably fitted for carrying on the puddling operation according to my
Invention; Fig. 2 is a longitudinal section taken through the middle of the
furnace; and Fig. 3 is a sectional plan of the same. a represents the molten
metal in the basin of the furnace; b, the rabble hole in the furnace door;
and c, a bent pipe, the forward end of which is admitted into the furnace
through the rabble hole, and which in the Drawing is shewn of equal diameter
throughout. This pipe c is attached by a universal joint to a pendent pipe d,
in connection with a steam boiler, and is intended to conduct a current of
steam beneath the surface of the molten metal. Affixed to the rear end of the
pipe c is a handle e, by means of which the attendant is enabled to direct the
orifice of the pipe to any part of the bed of the furnace.
The mode of operating with this apparatus is as follows:-The metal having
been brought in the ordinary manner to a molten state, the steam pipe c is
introduced by the attendant through the rabble hole into the fluid metal, its
orifice being submerged or kept below the surface of the metal. He then
moves the pipe about in the metal like a rabble or rake, and thereby causes
the steam to escape into the metal at all parts of the bed of the furnace. By
thus distributing the steam throughout the body of molten metal, the steam
will, as above stated, be resolved into its elements immediately on coming in
contact with the metal, and will cause the upheaving of the metal, and effect
rapid and continuous disturbance thereof, and its components will enter into
chemical combination with more or less of the carbon and sulphur present in
.the iron.
a
When the metal has been brought into a condition sufficiently decarbonized
or thickened, as to which the judgment of the workman will be his guide, the
steam pipe is to be removed, and the ordinary method is adopted for the purpose
of gathering the metal into balls, preparatory to the removal of the same from
the furnace to the tilt hammer or rolls. By these means the operation of
puddling is rendered much easier to the workman, and_more_uniform and
certain in its results, whilst the time in which it is effected is shortened, and
the purity, toughness, and strength of the iron resulting are increased in a
remarkable degree.
It will be evident that water may be forced beneath the surface of the
molten iron, though I do not recommend it, as the introduction of water, even
in comparatively small quantities, to such high temperatures might produce
destructive explosions. If introduced in suitable quantities to produce the

page_text: steam necessary for the operation, it would be so immediately converted into
steam that it may be said to be steam, and I consider that the introduction of
water or steam and water beneath the surface of the metal, so as to agitate the
metal and combine with any of its parts, would be an infringement of my
Invention.
.
The length of time during which the operation of steaming should be
conducted will depend in some degree upon the descriptions of iron operated
on. With a charge of molten iron consisting of three hundred and ninety-
two pounds Scotch No. 3 pig, and eighty-eight pounds of white Stafford-
shire pig iron, I have found that the introduction of steam varying from
two to five minutes immediately or shortly after the iron was melted, has been
attended with very beneficial results; I do not, however, limit myself to the
use of the steam for such periods, nor to such times for its introduction to the
iron. The pressure of the steam to be used with most advantage will be
easily found out by experience.
.
The more uniformly and equally the steam is diffused through the mass of
the molten iron, the more successful will the operation prove. If the steaming
be continued when the decarbonization of the iron has been nearly effected, a
waste of iron will ensue, as the oxygen of the steam will then combine with
the pure iron and form an oxide, though even then the hydrogen will be acting
beneficially as regards the quality of the iron resulting from the process, so
that if quality irrespective of yield or quantity be desired, the steaming process
may be longer continued than would be otherwise desirable, as the products of
combustion of the fuel will then have less chance of combining with and
injuring the iron than is the case under the existing mode.
Having now set forth the nature of my Invention of an Improvement in
the Process of puddling Iron, and explained the manner of carrying the same
into effect, I wish it to be understood that under the above in part recited
Letters Patent I claim, operating upon molten iron in the manner and for
the purpose above set forth.
In witness whereof, I, the said James Nasmyth, have hereunto set my
hand and seal, this First day of November, in the year of our Lord
One thousand eight hundred and fifty-four.
JAMES NASMYTH. (L.S.)