IMPROVEMENTS IN THE MANUFACTURE OF PIG IRON OR FOUNDRY METAL, AND IN MAKING AND TREATING CASTINGS OF SUCH METAL
Year: 1865

page_text: LETTERS PATENT to Henry Bessemer, of Queen Street Place, in the
City of London, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE
OF PIG IRON OR FOUNDRY METAL, AND IN MAKING AND TREATING CASTINGS OF
SUCH METAL,"
Scaled the 31st October 1865, and dated the 1st May 1865.
PROVISIONAL SPECIFICATION left by the said Henry Bessemer at the
Office of the Commissioners of Patents, with his Petition, on the 1st
May 1865.
I, HENRY BESSEMER, of Queen Street Place, in the City of London, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN THE
MANUFACTURE OF PIG IRON OR FOUNDRY METAL, AND IN MAKING AND TREATING
CASTINGS OF SUCH METAL," to be as follows:-
The object of my Invention is the production of an improved or superior
kind of pig iron, or foundry metal in the form of pigs, or in other forms
suitable for re-melting in a cupola or reverberatory furnace, and of being
mixed with ordinary foundry or cast iron, or of being used alone in the
founding of guns, wheels, engine or machine framing, and railway chairs, or
other articles that are or may be founded in ordinary cast iron.
When fluid malleable iron or steel is made from crude pig iron or other
carburet of iron by forcing atmospheric air therein, and is afterwards mixed
with fluid grey pig iron or cast iron, the strength of such pig or cast iron is much
increased, and the mixed metal acquires other valuable properties, rendering

page_text: it especially suitable for founding articles requiring great strength, or which
are exposed to much wear and abrasion; but such metal, when made at once
into castings, has a great tendency to form them unsound or full of bubbles
in consequence of the escape from the mixed metal of gaseous matter for some
time after the mixture is made, and which continues to be discharged from
the metal more or less during its cooling and solidification; now this defect
may be wholly or for the most part prevented by forming the mixed metals
into pigs or other suitable forms after such mixture is made, and which will
have again to be melted before the intended article is cast, thus freedom from
air bubbles and a more perfectly homogeneous casting will be obtained by the
use of such re-melted metal. It is well known that molten malleable iron or
steel cannot be kept in a fluid state in the Bessemer converting vessel but for
a very short period of time, and hence subjects the ironfounder to the necessity
of using it immediately after it is made, the converting vessel cannot therefore
become a source of supply from which the founder can draw off metal at short
intervals throughout the day, as he now does, from his cupola furnace. The
occasional requirement of this metal by the ironfounder in large quantities
would render necessary the erection of large and costly machinery which will
not be applicable to the production of small quantities of steel or malleable
iron for making the mixed metal sometimes required by him. This and other
causes incident to the employment of the mixture of malleable metal and cast
iron at the time when such mixture is made greatly retards the introduction
of this superior class of metal for general purposes. Now, therefore, the
object of this Invention is the production of a superior pig iron or foundry
metal that may be purchased by the ironfounder in a state suitable for his
use when re-melted in an ordinary furnace, either alone or mixed with a
further portion of pig or cast iron, so that he may at will produce from his
ordinary furnaces the required kind or quality of metal without the erection
of the plant and machinery required to manufacture steel or malleable iron by
the Bessemer process.
In carrying this Invention into practice I prefer to employ molten, crude,
or cast iron as it comes from the blast furnace, and to effect the improvement
in its quality consequent on the admixture therewith of malleable iron or steel
before such crude or cast iron is formed into pigs. For this purpose I erect
at a convenient distance from the blast furnace a Bessemer converting appa-
ratus, in which a portion of the metal is converted into malleable iron or steel,
or in which some other kind or quality of pig or carburet of iron is so con-
verted. The crude metal from the blast furnace is to be run into a receiver
of sufficient size to admit (by preference) all the iron drawn from the blast

page_text: or
furnace at one tapping, and also to contain as much converted metal as it
may be desired to run or mix therein. The said receiving vessel I prefer to
mount on a moveable platform weighing machine, so as to ascertain the
weight of crude metal run therein, the required quantity of malleable iron or
steel to be mixed therewith having been made in the converting vessel is also
to be poured or run into the receiver and be mixed thoroughly with the crude
metal, after which the fluid mixture of metals is to be run or poured into open
sand or iron moulds, as in the ordinary mode of making pig iron, or it may be
otherwise moulded, so as to be readily broken up into lumps or pieces of a
size suitable for melting in the cupola or reverberatory furnace, in which it
may at any future time be melted, and used alone or mixed with other pig or
cast iron, and be then poured or run into suitable moulds, and thereby formed
into a variety of useful articles.
I would observe that I prefer to use hematite pig iron, or Swedish or other
foreign charcoal pig iron, for the production of malleable iron or steel for the
purposes of my said Invention, either with or without the employment of a
portion of manganesian pig iron, as commonly practised; and I also prefer to
use a good strong grey pig iron, of No. 1 or No. 2 quality, to be mixed there-
with. The addition of steel or malleable iron made from grey hematite iron
by the Bessemer process will be found to greatly improve the quality of Scotch
pig iron or other qualities of iron made from blackband ironstone. For
many purposes it will be found that from 10 to 20 per cent. of molten
malleable irou or steel mixed with from 80 to 90 per cent. of grey pig iron
will answer well, but where great hardness or strength is required in castings
to be made of the improved foundry metal for rolls, stamps, hammer faces, or
other like purposes, from 20 to 60 per cent. of malleable iron or steel may be
employed in combination with from 40 to 80 per cent. of good grey iron.
In order to facilitate the use of this metal a scale of numbers may be
established, so as to readily indicate to the ironfounder the quality of this
improved foundry metal, thus Nos. 1, 2, 3, 4, 5, and 6, may indicate the
presence of 10, 20, 30, 40, 50, or 60 per cent. of malleable metal in the pig.
The founder may then use either of these numbers or qualities of metal that
best suit him, or he may readily make any intermediate grade or quality by
melting together any desired quantity of two of these numbers, or by mixing
with either of them a further portion of pig or cast iron.
I desire it to be understood that although I prefer in most cases that the
improved foundry metal should be made while the crude metal forming part
thereof is still in a fluid state from the blast furnace, the same general results
will follow if for this purpose, re-melted pig iron be employed; in some cases

page_text: it may indeed be found preferable to do so, as it will admit of the mixing
together of any varieties of pig or cast iron with the malleable metal that may
be found desirable. I would also remark that although I have stated that
malleable iron and steel may both be employed for the purpose of making
this improved pig or foundry metal, I nevertheless greatly prefer to use a very
soft or "mild" quality of steel, as it will cast more soundly than metal pre-
pared with wholly decarbonized iron, and also enables the manufacturer to
employ a somewhat greater quantity than could be used if hard or highly-
carburetted steel were employed.
When castings are made with the improved foundry metal which contains
a large proportion of malleable iron or steel the metal is sometimes very hard,
and is somewhat brittle when first cast; this condition of the metal is
removed and a much greater degree of toughness is obtained by re-heating or
annealing the casting, that is, simply subjecting it to a red heat for a sufficient
time in a close furnace or chamber, and then allowing it to cool gradually.
This treatment of the casting will be quite unnecessary where steel or malleable
iron forms only a very small proportion of the mixed metal.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Henry Bessemer in the Great Seal Patent Office on the
1st November 1865.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, IJENRY
BESSEMER, of Queen Street Place, in the City of London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the First day of May, in the year of our Lord
One thousand eight hundred and sixty-five, in the twenty-eighth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Henry Bessemer, Her special licence that I, the said Henry
Bessemer, my executors, administrators, and assigns, or such others as I, the
said Henry Bessemer, 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 "IM-
PROVEMENTS IN THE MANUFACTURE OF PIG IRON OR FOUNDRY METAL, AND IN
MAKING AND TREATING CASTINGS OF SUCH METAL," upon the condition (amongst
others) that I, the said Henry Bessemer, my executors or administrators, by an

page_text: 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 he
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 Henry Bessemer, 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:
The object of my Invention is the production of an improved or superior-
kind of pig iron, or foundry metal in the form of pigs, or in. other forms
suitable for re-melting in a cupola or reverberatory furnace, and of being.
mixed with ordinary foundry or cast iron, or of being used alone in the
founding of guns, wheels, engine or machine framing, and railway chairs, or
other articles that are or may be founded in ordinary cast iron.
When fluid malleable iron or steel is made from crude pig iron or other
carburet of iron by forcing atmospheric air therein, and is afterwards mixed
with fluid grey pig iron or cast iron, the strength of such pig or cast iron is.
much increased, and the mixed metal acquires other valuable properties,.
rendering it equally suitable for founding articles requiring great strength, or
which are exposed to much wear and abrasion; but such metal, when made
at once into castings, has a great tendency to form them unsound or full of
bubbles in consequence of the escape from the mixed metal of gaseous matter
for some time after the mixture is made, and which continues to be discharged
from the metal more or less during its cooling and solidification; now this.
defect may be wholly or for the most part prevented by forming the mixed
metals into pigs or other suitable forms after such mixture is made, and
which will have again to be melted before the intended article is cast, thus
freedom from air bubbles and a more perfectly homogeneous casting will be
obtained by the use of such re-melted metal. It is well known that molten
malleable iron or steel cannot be kept in a fluid state in the Bessemer con-
verting vessel but for a very short period of time, and hence subjects the
ironfounder to the necessity of using it immediately after it is made. In all
those cases where the Bessemer malleable iron or steel is intended to be
mixed with molten grey iron for the purpose of producing castings the con-
verting vessel cannot become a source of supply from which the founder can
draw off metal at short intervals throughout the day as he now does from his
cupola furnace. The occasional requirement of this Bessemer metal by the
ironfounder in large quantities would render necessary the erection of large

page_text: and costly machinery for the purpose of producing it from pig iron, and this
large-sized converting apparatus will not be applicable to the production of
small quanties of steel or malleable iron for making the mixed metal some-
times required by him. This and other causes incident to the employment of
the mixture of malleable metal and cast iron at the time when such mixture
is made greatly retards the introduction of this superior class of metal for
general purposes. Now, therefore, the object of this Invention is the pro-
duction of a superior pig iron or foundry metal that may be purchased by the
ironfounder in a state suitable for his own use when re-melted in an ordinary
furnace, either alone or mixed with a further portion of pig or cast iron, so
that he may at will produce from his ordinary furnace the required kind or
quality of metal without the erection of the plant and machinery required to
manufacture steel or malleable iron by the Bessemer process.
In carrying this Invention into practice I prefer to employ molten, crude,
or cast iron as it comes from the blast furnace, and to effect the improvement
in its quality consequent on the admixture therewith of malleable iron or steel
I erect
before such crude or cast iron is formed into pigs. For this purpose
at a convenient distance from the blast furnace a Bessemer converting appa-
ratus, in which a portion of the metal is converted into malleable iron or steel,
or in which some other kind or quality of pig or carburet of iron is so con-
verted. The crude metal from the blast furnace is to be run into a receiver
of sufficient size to admit (by preference) all the iron drawn from the blast
furnace at one tapping, and also to contain as much converted metal as it
may be desired to run or mix therein. The said receiving vessel I prefer to
mount on a moveable platform or weighing machine, so as to ascertain the
weight of crude metal run therein, the required quantity of malleable iron or
steel to be mixed therewith having been made in the converting vessel is also
to be poured or run into the receiver and be mixed thoroughly with the crude
metal, after which the fluid mixture of metals is to be run or poured into open
sand or other moulds, as in the ordinary mode of making pig iron, or it may
be otherwise moulded, so as to be readily broken up into lumps or pieces of a
size suitable for melting in the cupola or reverberatory furnace, in which it
may at any future time be melted, and be used alone or mixed with other pig
or cast iron, and be then poured or run into suitable moulds, and thereby
formed into a variety of useful articles.
The mixing vessel or receiver into which the fluid crude iron from the blast
furnace is to be run I prefer to make of stout plate iron, in a similar manner
and of a similar form to the ladles now generally employed by ironfounders,
its interior also being coated with loam in the manner usually practised in

page_text: such cases. This receiver or ladle may be suspended from a crane of ordinary
construction or be mounted on a hydraulic crane, by means of which it may.
be lowered into a pit, so as to allow the fluid metal, as it flows from the blast
furnace, to pass along a gutter into it at the bottom of the pit. A weighing
machine is to be fixed in such a position that the ladle or receiver may rest
upon it, and thus the workmen will be enabled to ascertain the weight of the
fluid metal which flows into it, and will be thus able to regulate the quantities
of the mixed metals; tho crane will serve to raise the receiver or ladle to
such a beight, and to move it round into such a position as to admit of the
running pouring out of fluid mixture in the channels of the ordinary "pig bed,"
or into other suitable moulds. The mixture of the malleable iron or steel
with the molten crude iron will in general take place with sufficient equality
by the mere act of running or pouring the one fluid into the other, because a
considerable amount of ebullition takes place in so doing owing to the dis-
engagement of gaseous matter; but a further mixing of the fluid by mechanical
agitation may be effected, if found desirable, by means similar to that described
in a Patent granted to me for "Improvements in the Manufacture and Treat-
ment of Malleable Iron and Steel, and in Furnaces, Machinery, and Apparatus
employed in such Manufacture," and bearing date the 13th day of January
1863, No. 114.
I would observe that I prefer to use hæmatite pig iron, or Swedish or
other foreign charcoal pig iron, for the production of malleable iron or steel,
for the purposes of my said Invention, either with or without the employment
of a portion of manganesian pig iron, as commonly practised; and I also
prefer to use a good strong grey pig iron, of No. 1 or No. 2 quality, to be
mixed therewith. I do not, however, confine myself to any particular "number"
or quality of pig iron in carrying out my said Invention, because the numerous
and varied purposes for which the improved foundry metal may be employed
may render useful the employment of any quality, from soft grey No. 1 to the
bardest white iron. The addition of steel or malleable iron made from grey
hæmatite iron by the Bessemer process will be found to greatly improve the
quality of Scotch pig iron, or other qualities of iron made from blackband
ironstone. For many purposes it will be found that from 10 to 20 per cent.
of molten malleable iron or steel mixed with from 80 to 90 per cent. of grey
pig iron will answer well, but where great bardness or strength is required in
castings to be made of the improved foundry metal for rolls, stamps, hammer
faces, or other like purposes, from 20 to 60 per cent. of malleable iron or
steel may be employed in combination with from 40 to 80 per cent. of good
grey iron.
i

page_text: In order to facilitate the use of this metal a scale of numbers may be
established, so as to readily indicate to the ironfounder the quality of this
improved foundry metal, thus Nos. 1, 2, 3, 4, 5, and 6, may indicate the
presence of 10, 20, 30, 40, 50, or 60 per cent. of malleable metal in the pig.
The founder may then use either of these numbers or qualities of metal that
best suit him, or he may readily make any intermediate grade or quality by
melting together any desired quantity of two of these numbers, or by mixing
with either of them a further portion of pig or cast iron.
I desire it to be understood that although I prefer in most cases that the
improved foundry metal should be made while the crude metal forming part
thereof is still in a fluid state from the blast furnace, the same general results
will follow if for this purpose re-melted pig iron be employed; in some cases
it may indeed be found preferable to do so, as it will admit of the mixing
together of any varieties of pig or cast iron with the malleable metal that may
be found desirable. I would also remark, that although I have stated that
malleable iron and steel may both be employed for the purpose of making
this improved pig or foundry metal, I nevertheless greatly prefer to use a very
soft or "mild" quality of steel, as it will cast more soundly than metal pre-
pared with wholly decarbonized iron, and also enables the manufacturer to
employ a somewhat greater quantity than could be used if hard or highly-
carburetted steel were employed.
When castings are made with the improved foundry metal, which contains
a large proportion of malleable iron or steel, the metal is sometimes very hard,
and is somewhat brittle when first cast; this condition of the metal is
removed and a much greater degree of toughness is obtained by re-beating or
annealing the casting, that is, simply subjecting it to a red heat for a sufficient
time in a close furnace or chamber, and then allowing it to cool gradually.
This treatment of the casting will be quite unnecessary where steel or malleable
iron forms only a very small proportion of the mixed metal.
I desire it to be understood that I am aware that it has been proposed by
others to make, and I have already practised the casting of articles in metal
composed of steel or malleable iron mixed with a large proportion of pig iron,
so as to constitute an improved cast iron (not malleable or capable of being
forged or rolled after the manner of malleablé iron or steel), but such castings
having been made or proposed to be made by mixing the said metals, and
while still retaining their fluidity, casting such fluid mixture into the desired
article. I mention this fact that it may be understood that in these Letters
Patent I lay no claim thereto; I also desire it to be understood that I am
aware that very small quantities of grey pig iron and other pig iron have been

page_text: mixed with malleable iron and steel in the steel manufacture, pig or carburet
of iron being used in such quantities as not to destroy the malleability of the
compound, such mixture of metal being cast into ingots for forging or rolling,
or into castings not to be so treated, and such casting operation taking place
soon after the said admixture has been made, and before the metal so com-
bined has been allowed to solidify, I therefore lay no claim to such mixture
of metals under these Presents, but what 1 claim is the manufacture of pig
iron or foundry metal and the making and treating castings of such metal, as
herein described.
In witness whereof, I, the said Henry Bessemer, have hereunto set my
hand and seal, this First day of November, in the year of our Lord
One thousand eight hundred and sixty-five.
HENRY BESSEMER. (L.S.)