IMPROVEMENTS IN THE MANUFACTURE OF STEEL
Year: 1868

page_text: LETTERS PATENT to Charles Denton Abel, of No. 20, Southampton
Buildings, Chancery Lane, in the County of Middlesex, Patent
Agent, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF
STEEL." A communication from abroad by Thomas Schoenberger
Sealed the 12th March 1869, and dated the 28th November 1868.
PROVISIONAL SPECIFICATION left by the said Charles Denton Abel
at the Office of the Commissioners of Patents, with his Petition, on
the 28th November 1868.
I, CHARLES DENTON ABEL, of No. 20, Southampton Buildings,
5 Chancery Lane, in the County of Middlesex, Patent Agent, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN THE MANU-
FACTURE OF STEEL," to be as follows:-
This Invention relates to the manufacture of steel by means of the
new article known as "pig bloom" or "pig scrap" according to the

page_text: manner in which it is produced by the process described in the Specifi-
cation to certain Letters Patent for which I am applying, bearing date
the 23 November 1868, No. 3569.
"Pig bloom, or pig scrap, so called in the said Specification, consists of
a conglomerate of cast iron and an oxide or oxides, usually the oxide of
iron, intimately mixed together while one of the ingredients (cast iron or
ore) is fluid and the other is solid, so as to form at once in the mixing a
somewhat loose textured yet solid (as distinguished from a fluid) mass.
For the successful conduct of the process I am about to describe it is
important that the pig bloom or pig scrap, whichever is used, should
contain such a relative proportion of cast iron and oxide as to yield a
steel of the required degree of hardness, because different qualities of cast
iron and different kinds of ore yield in this respect different results. I
therefore first make a small amount of pig scrap and subject it to the
process hereafter described to test the result before preparing the pig
bloom or pig scrap in large quantities. Having thus determined the
proper formula for mixing the cast iron and ore (or oxide) to give the
desired result, I proceed to make a large quantity of pig bloom' or
'pig scrap' for use in the making of steel according to the present
Invention, taking care to have the oxide and cast iron mixed as inti-
mately as possibly. If pig scrap is used, which is in small pieces of
loose texture, it is carefully picked over, and those pieces which are seen
to contain any raw cast iron being rejected, the residue, when cooled, is
screened so as to remove any loose ore from the mass. The pieces are
then placed in crucibles and treated as a substitute for blistered steel or
wrought iron in the manufacture of cast steel, the process being con-
ducted in similar crucibles and furnace and in the same manner as is
practised in making crucible steel, excepting that pig scrap or pig
bloom broken up is used instead of blister steel or wrought iron. By
first making a few sample ingots of steel from the pig scrap which has been
carefully selected and screened, as before described, the character of the
resultant steel is ascertained, and any error in the proportion of ingre-
dients used in the preparation of the pig scrap is corrected in conducting
the process on a larger scale by adding charcoal in the crucible if the
test steel ingots are formed too soft or wrought iron if they have
proved too hard. Instead of melting the pig scrap in crucibles as above
described it may be melied down in an open furnace, in which case the

page_text: pig bloom, which is a loose spongy mass, may be used, but in this case
in order to insure success, care must be taken in making the pig bloom
or pig scrap" not to have an excess of oxide, but to have such a relative
proportion of ore and cast iron as will allow of the mass being melted,
as otherwise the ore, being in excess, would remove the carbon and the
mass would not melt by such treatment.
Another modification of this process is to take the pig scrap or pig
bloom broken up into small pieces and introduce it from time to time in
small quantities into a bath of molten cast iron until the desired degree
of carbonization is attained. In this process the pieces of pig scrap or
pig bloom (each of which is a conglomerate of cast iron and ore, and
some parts of which are in a transition state nearly approaching to
malleable iron) serve to dilute the carbon of the cast iron, and at the
same time the oxide of iron which was mechanically imprisoned in the
conglomerate aids in the process of dilution. Thus the process of
making steel by diluting the carbon is carried on with both malleable
iron and oxide of iron at the same time, whereas heretofore it has
been found impracticable to use the oxide of iron for this purpose,
because when free it destroys the furnace; it may however be used by
the present method as above described with safety to the furnace and
greatly facilitates the reduction of the quantity of carbon. Another
advantage peculiar to this process is that the material introduced into
the cast-iron bath is of so open, porous, and spongy a texture as to be
more rapidly melted, and is besides in a chemical condition better
adapted to produce the desired result than manufactured wrought iron.
This method also cheapens the manufacture of steel, as the process or
processes necessary to the manufacture of wrought iron are omitted, the
pig bloom or pig scrap being used without being previously converted
into malleable iron.
Still another modification of the process is as follows:-Instead of
introducing the raw pig scrap or spongy pieces of pig bloom directly into
the bath of molten cast iron, I charge them (the pieces of pig scrap or
pig bloom) into a separate heating furnace which may be situate near to
the furnace containing the bath of molten cast iron; they are there.
exposed to a high temperature and allowed to remain at a white heat f
some time so as to sweat out the impurities, and they are then transfed
with as little loss of heat as possible into the bath of molten cas
on in

page_text: which they are melted more rapidly than manufactured wrought iron
would be, owing to the open, spongy, and loose texture of the pig bloom.
This method has the disadvantage of not introducing the iron orc
into the bath, as it has become chemically incorporated with the mass
in which it was before mechanically present by reason of the heat of the
furnace, and hence it will be a less expeditious as well as more costly
process than that before described, but it will be found better suited for
making extra qualities of steel and for utilizing materials too impure
for other modes of treatment. This last-described method obviates the
necessity hitherto experienced in the ordinary processes of steel manu-
facture of using none but the finest quality of materials at the highest
cost, because this treatment removes a much larger amount of impurities
than can be removed by the processes heretofore employed.
The furnaces and appliances used in the improved process as described
in its various modifications may be such as are ordinarily employed in
the manufacture of steel, and therefore need no further explanation here.
""
By the above described application of "pig bloom" or "pig scrap
to the manufacture of steel the operation is greatly simplified in detail and
reduced in expense. Crucible steel can be produced with great facility,
the method I have described giving complete control of the process.
In the open furnace treatment which I have described the product of
a blast furnace can be run at about equal cost into cast pig or into
pig blooms and pig scrap, and from these two articles thus produced
directly from the blast furnace the steel ingot is manufactured with only
one after heating.
In this Specification the term "wrought iron" is used to designate
malleable iron which has been worked, whereas the pig bloom or
"pig scrap' used in the improved process, after it has been exposed to a
high heat becomes "malleable," but is not " wrought," retaining the
open spongy texture which wrought or worked iron does not possess,
and which renders the use of the pig bloom either before or after it is
converted into malleable iron peculiarly adapted to the manufacture of
steel in the manner I have above described.

page_text: SPECIFICATION in pursuance of the conditions of the-Letters Patent,
filed by the said Charles Denton Abel in the Great Scal Patent
Office on the 27th May 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
DENTON ABEL, of No. 20, Southampton Buildings, Chancery Lane, in
the County of Middlesex, Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-eighth day of November, in the
year of our Lord One thousand eight hundred and sixty-eight, in the thirty-
second year of Her reign, did, for Herself,, Her heirs and successors,
give and grant unto me, the said Charles Denton Abcl, Her special
licence that I, the said Charles Denton Abel, my executors, adminis-
trators, and assigns, or such others, as I, the said Charles Denton.
Abel, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times, there-
after 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," (a communication to me
from abroad by Thomas Schoenberger Blair, of Pittsburg, Penn-
sylvania, United States of America, upon the condition (amongst others)
that I, the said Charles Denton Abel, 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 Charles Denton Abel,, 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 :-
This Invention relates to the manufacture of steel by means of t
new article known as "pig bloom
or "pig scrap" according the
manner in which it is produced by the process described
the:

page_text: Specification to certam Letters Later gra
November 1868, No. 3569.
"Pig bloom," or "pig scrap," so called in the said Specification,
consists of a conglomerate of cast iron and an oxide or oxides, usually
the oxide of iron, intimately mixed together while one of the ingredients
is fluid and the other is solid, so as to form at once in the mixing a
somewhat loose textured yet solid (as distinguished from a fluid) mass.
For the successful conduct of the process I am about to describe it is
important that the pig bloom or pig scrap, whichever is used, should
contain such a relative proportion of cast iron and oxide as to yield a steel
of the required degree of hardness, because different qualities of cast iron
and different kinds of ore yield in this respect different results; I there-
fore first make a small amount of pig scrap and subject it to the process
liercafter described to test the result before preparing the pig bloom or
pig scrap in large quantities. Having thus determined the proper
formula for mixing the cast iron and ore (or oxide) to give the desired
result, I proceed to make a large quantity of "pig bloom" or "pig
scrap "for use in the making of steel according to the present Invention,
taking care to have the oxide and cast iron mixed as intimately as
possible. If pig scrap is used, which is in small pieces of loose texture,
it is carefully picked over, and those pieces which are seen to contain
any raw cast iron being rejected, the residue when cooled is screened so
as to remove any loose ore from the mass. The pieces are then placed
in crucibles and heated as a substitute for blistered steel or wrought
iron in the manufacture of cast steel, the process being conducted in
similar crucibles and furnaces and in the same manner as is practised in
making crucible steel, excepting that pig scrap or pig bloom broken up
is used instead of blister steel or wrought iron. By first making a few
sample ingots of steel from the pig scrap which has been carefully
selected and screened as before described, the character of the resultant
steel is ascertained, and any error in the proportion of ingredients used
in the preparation of the pig scrap is corrected in conducting the process
on a larger scale by adding charcoal in the crucible if the test steel
ingots are formed too soft, or wrought iron if they have proved too hard.
nstead of melting the pig scrap in crucibles, as above described, it may
belted down in an open furnace, in which case the pig bloom which
is a
se spongy mass may be used; but in this case in order to insure

page_text: "
success care must be taken in making the "pig bloom" or "pig scrap
not to have an excess of oxide, but to have such a relative proportion of
ore and cast iron as will allow of the mass being melted, as otherwise the
ore being in excess would remove the carbon and the mass would not
melt by such treatment.
Another modification of this process is to take the pig scrap or pig
bloom broken up into small pieces and introduce it from time to time
in small quantities into a bath of molten cast iron until the desired
degree of carbonization is attained. In this process the pieces of pig
scrap or pig bloom (each of which is a conglomerate of cast iron and ore,
and some parts of which are in a transition state nearly approaching to
malleable iron) serve to dilute the carbon of the cast iron, and at the
same time the oxide of iron which was mechanically imprisioned in the
conglomerate aids in the process of dilution. Thus the process of
making steel by diluting the carbon is carried on with both malleable
iron and oxide of iron at the same time, whereas heretofore it has been
found impracticable to use the oxide of iron for this purpose, because
when free it destroys the furnace, it may however be used by the present
method, as above described, with safety to the furnace and greatly
facilitates the reduction of the quantity of carbon. Another advantage
peculiar to this process is that the material introduced into the cast-iron
bath is of so open, porous, and spongy a texture as to be more rapidly
melted, and is besides in a chemical condition better adapted to produce
the desired result than manufactured wrought iron. This method also
cheapens the manufacture of steel, as the process or processes necessary
to the manufacture of wrought iron are omitted, the pig bloom or pig
scrap being used without being previously converted into malleable
iron.
Still another modification of the process is as follows:-Instead of
introducing the raw pig scrap or spongy pieces of pig bloom directly:
into the bath of molten cast iron I charge them (the pieces of pig scrap
or pig bloom) into a separate heating furnace, which may be situate near
to the furnace containing the bath of molten cast iron; they are there
exposed to a high temperature and allowed to remain at a white heat for
some time so as to sweat out the impurities, and they are then transferred
with as little loss of heat as possible into the bath of molten cast iron, in
which they are melted more rapidly than manufactured wrought iron

page_text: would be, owing to the open, spongy, and loose texture of the pig bloom.
This method has the disadvantage of not introducing the iron ore into
the bath, as it has become chemically incorporated with the mass. in
which it was before mechanically present by reason of the heat of the
furnace, and hence it will be a less expeditious as well as more costly
process than that before described, but it will be found better suited for
making extra qualities of steel and for utilizing materials too impure for
other modes of treatment. This last described method obviates the
necessity hitherto experienced in the ordinary processes of steel manu-
facture of using none but the finest quality of materials at the highest
cost, because this treatment removes a much larger amount of im-
purities than can be removed by the processes heretofore employed.
The furnaces and appliances used in the improved process as described
in its various modifications may be such as are ordinarily employed.
in the manufacture of steel, and therefore need no further explanation
here.
"
By the above described application of "pig bloom
or "pig scrap
" to
the manufacture of steel the operation is greatly simplified in detail and
reduced in expense. Crucible steel can be produced with great facility,
the method I have described giving complete control of the process.
In the open furnace treatment which I have described the product of
à blast furnace can be run at about equal cost into cast pig or into "pig
bloom" and "pig scrap," and from these two articles thus produced
directly from the blast furnace the steel ingot is manufactured with only
one after heating.
or'
In this Specification the term "wrought iron" is used to designate
malleable iron which has been worked, whereas the "pig bloom"
"pig scrap" used in the improved process after it has been exposed to
a high heat becomes malleable, but is not wrought, retaining the open
spongy texture which wrought or worked iron does not possess, and
which renders the use of the "pig bloom" either before or after it is
converted into malleable iron peculiarly adapted to the manufacture of
steel in the manner I have above described.
Having thus described the nature of this Invention, and in what
manner the same is to be performed, as communicated to me by my
foreign correspondent, what I claim is,-

page_text: First. The manufacture of cast steel in the crucible from "pig bloom"
or "pig scrap," substantially as herein-before described.
Second. The manufacture of steel by melting down in an open furnace
"pig bloom" or "pig scrap'
or "pig scrap" composed of a mixture of cast iron and
an oxide or oxides in such relative proportion of metal and oxide as to
give the necessary ratio between the oxygen, carbon, and iron to produce
the desired result, substantially as herein-before described.
Third. The manufacture of steel from cast iron by adding to the cast
iron in a melted state "pig bloom" or "pig scrap," substantially in the
manner herein-before described.
Fourth. The production of steel from cast iron and malleable iron by
melting the cast iron and fusing in it a sponge of wrought iron obtained
from "pig bloom" in the manner herein-before described.
In witness whereof, I, the said Charles Denton Abel, have here-
unto set my hand and seal, this Twenty-seventh day of May,
in the year of our Lord One thousand eight hundred and sixty-
nine.