Improvements in the Manufacture of Steel by the Bessemer or Open Hearth Process.
Year: 1897

page_text: Date of Application, 6th Apr., 1897--Accepted, 14th Aug., 1897
Improvements in the Manufacture of Steel by the Bessemer or
Open Hearth Process.
We, CHARLES HOWARD FOOTE, WILLIAM ROSE WALKER, and EDMUND ARTHUR
STANLEY CLARKE all of No. 142 Adams Street (1027 Rookery Building), in the City of
Chicago, County of Cook, State of Illinois, United States of America, Manufacturers,
do hereby declare the nature of this invention, and in what manner the same is
to be performed to be particularly described and ascertained, in and by the following
statement —
In the Bessemer process of manufacturing steel it is customary after the metal
has been sufficiently refined, to add to the charge of metal within the converter,
spiegel containing carbon, manganese and silicon in definite percentages in order to
give the desired character to the converter product. The method of producing this
spiegel as at present practiced, consists in charging a blast furnace with a
manganiferous ore from which the spiegel is to be made, and from time to time the
furnace is tapped and the smelted spiegel is run into pigs. These pigs of spiegel are
then analyzed and sorted and stacked in separate piles with reference more
particularly to their manganese content. A cupola is afterwards charged with the pigs
of spiegel together with a desired proportion of pig-iron and fuel in order to give to
the product of the cupola the desired percentages of manganese, silicon and carbon.
This cupola product is used in molten condition in making the additions to the charges
of the Bessemer converter at the end of the refining operation.
The charging of the blast furnace with manganiferous ore necessary to produce the
spiegel has commonly been effected with only about the same degree of care that is
exercised in the charging of blast furnaces used in the production of pig-iron and it
has been found that a very material variation exists in the pigs of spiegel from the
furnace, and this variation exists not only in pigs obtained from different casts of the
same furnace but in pigs obtained from different portions of the same cast or heat.
The variations in the spiegel pigs from the blast furnace have been due largely to the
fact that the manganiferous ore from which the pigs are made varies materially in its
character and grade, the variations being much greater than are found in ores used in
the manufacture of pig-iron. Manganiferous ore such as is suitable for the
manufacture of spiegel is usually found in pockets so that such ore, even from the
same locality and from the same mines, is apt to vary to a very considerable extent,
particularly as to its manganese content. These variations in the character and grade
of the pigs obtained from a spiegel furnace have been looked upon as in great
measure unavoidable and this has constituted one reason why it has been heretofore
deemed impossible to use spiegel direct from the blast furnace as a recarburizing
addition to the charge of a Bessemer converter or open hearth furnace, because in
modern steel making the specifications for carbon, silicon and manganese are so rigid

page_text: and exact and the limits of variation allowed are so slight that if the spiegel vary
considerably either in manganese or silicon or both, it cannot be used, and variations
in the manganese content of the spiegel are found particularly objectionable.
Another reason why it has been heretofore thought impossible to use spiegel direct
from the blast furnace as an addition to the charge of a Bessemer converter, is that
it was supposed that the molten spiegel would chill in the ladles before it could be
delivered to the converter, and this supposedly fatal objection to the use of spiegel
direct from the furnace has arisen because of the rapidity with which the pigs of
spiegel set and harden within the casting beds.
This usual method of producing spiegel is very expensive, not only because of the
cost incident to the labor of casting the spiegel into pigs, transporting and handling
the pigs, and the cost incident to re-melting the metal in a cupola, but it
is found that a most serious and wasteful loss of manganese occurs by
reason of its oxidation in the cupola. A further objection to this usual
method of producing spiegel is that it is frequently desired to change the
grade or character of the spiegel to be used as a recarburizing addition in the
Bessemer converter or open hearth. furnace upon very short notice, yet a change in
the character of the spiegel delivered from a cupola cannot be effected with certainty
inside of several hours. Moreover, with this usual method of producing spiegel it is
obvious also that in the re-melting of the pigs of spiegel within the cupola, the
addition of pig-iron therein reduces to a material extent the manganese content of
the spiegel. Hence it is that, in order to obtain from the blast furnace pigs of spiegel
sufficiently high in manganese to permit of re-melting with pig-iron in a cupola, it
is necessary to use high grade manganiferous ores, which, being found only in certain
localities, are comparatively scarce and expensive. On the other hand, a lower grade
of manganiferous ores, suitable for producing a lower grade of spiegel, can be obtained
in many localities and at comparatively much less cost.
The present invention has for its object to overcome the objections incident to the
above described usual method of producing and using spiegel as a recarburizing
addition for the charge of a Bessemer converter or open hearth furnace and with this;
object in view the invention consists first in producing a spiegel in a smelting furnace
and thereafter without re-melting said spiegel adding the same to the charge of a
Bessemer converter or open hearth furnace. By this first feature of invention a very
great saving in cost of manufacture is effected, since obviously the time
and labor required to cast the smelted spiegel into pigs, to transport, and
handle these pigs, the fuel, labor and repairs incident to the re-melting
of the pigs in a cupola and the loss of manganese and silicon by oxidation in
the re-melting of the pigs within a cupola are avoided. Secondly, the invention consists
in taking the spiegel while still in the molten condition in which it is run from
a smelting furnace (i.c., without re-melting), making suitable additions of proper
quantity and character to said molten spiegel in order to impart to said spiegel a
character that shall adapt it for use as a recarburizing addition to the charge of a
Bessemer converter or open hearth furnace, and thereafter adding said modified
spiegel to the charge of the converter or open hearth furnace as a recarburizing
addition. By this second feature of the invention the grade or character of the spiegel 4
as it comes from the smelting furnace may be so modified as to adapt it for use and
in order to enable changes in the grade or character of the spiegel required by
different kinds of work to be very quickly effected. Thirdly, the invention consists
in charging a smelting furnace with ore so low in manganese as to give to the product
of the furnace a manganese percentage below that required in the spiegel that is to 5
be run into the Bessemer converter or open hearth furnace as a recarburizing addition,
and afterwards tapping the smelted spiegel from the blast furnace and mixing with
said smelted spiegel after it is discharged from the blast furnace, a metallic addition
containing a sufficient excess of manganese to adapt the spiegel as a recarburizing
addition to the charge of a Bessemer converter or open hearth furnace. By this third 5
feature of the invention it becomes possible to use in the smelting furnace much
Lower and cheaper grades of manganiferous ores than have heretofore been employed

page_text: in the manufacture of spiegel. Fourthly, the invention consists in adding to the
spiegel as it comes from the smelting furnace and before it is delivered into a mixing
chamber adapted to receive successive casts of spiegel from the smelting furnace,
suitable metallic additions adapted to give to the spiegel the desired grade or
5 character, and by this feature of the invention greater uniformity of distribution of
the manganese throughout the mass of spiegel is insured, since the mixing of the
metallic additions with the smelted spiegel before it is run into the mixing
chamber insures a much more thorough and effective admixture of such additions
with the mass of spiegel.
When the first broad feature of the invention is to be employed without the practice'
of the remaining features above recited (and preferably in such event also) the
manganiferous ore delivered to the spiegel smelting furnace should be carefully
selected and graded before it is charged into the furnace and the furnace should be
carefully burdened so that a much more uniform grade or character of spiegel can be
obtained than has been heretofore deemed possible and by thus exercising extreme
care in the proper charging and burdening of the furnace particularly with respect to
the precise grade and character of the inanganiferous ore used therein, a spiegel
suitable for direct additions to the charges of a Bessemer converter or open hearth
furnace may be obtained. So also notwithstanding the fact that molten spiegel sets
and hardens so rapidly when cast into pigs, it has been discovered that it may
nevertheless be transported in ladles from the blast furnace to the Bessemer converter
or open hearth furnace without danger of becoming chilled in transit.
In the practical operation of the invention it is preferable, although not essential,
to use two or more blast furnaces for producing the spiegel and it is preferred that
these furnaces shall be of comparatively small capacity, the reason for employing two
furnaces being that if any accident, such as a leaky bosh plate, or tuyere or a
"scaffold" in one furnace should occur, the other furnace may be relied upon to give
the desired grade and character of spiegel. The object in using furnaces of smaller
capacity than are commonly employed in the manufacture of spiegel is that with such
small furnaces a more careful charging and more uniform and exact operation can be
relied upon.
In the preferred manner of practicing the invention the spiegel will be
drawn from the blast furnace either into a large ladle adapted to hold one or more'
casts of the furnace and thereby serve as a mixing chamber wherein a more uniform
distribution of the manganese, silicon and carbon contents of the spiegel may be
effected, or the metal from the spiegel furnace may be transported in suitable smaller
ladles to a mixing chamber of a capacity adapted to receive one or several heats or
casts of the spiegel furnace. This mixing chamber may be of that kind commonly
employed at those steel works at which the direct process of manufacturing steel
(without the intermediary of a cupola for re-melting the pig-iron) is practiced and at
which the casts of molten pig-iron from the blast furnaces are delivered into a large
mixing chamber in order to secure a more uniform grade or character of the iron.
The spiegel thus delivered direct from the spiegel furnace to the large ladle or by
means of smaller ladles to a mixing chamber of large capacity, will be tapped or
poured from such. large ladle or from such mixing chamber in suitable quantities for
addition to the charges of a Bessemer converter or open hearth furnace at the end of
the refining operation. When such large ladle or separate mixing chamber is thus
employed the mass of spiegel therein will be replenished from time to time by
successive casts from the spiegel furnace or furnaces.
In the preferred manner of practicing the second feature of this invention in which
suitable additions of proper quantity and character are made to the molten spiegel in
order to impart thereto a grale or character which shall adapt it for use as a
recarbarizing addition to the charge of a Besseiner converter or open hearth furnace.
The furnace is preferably burdened so as to produce a spiegel of such manganese
content that even in the greatest ordinary variation of product from the normal
product of the furnace the manganese percentage will still be higher than the highest
nanganese percentage that it is proposed to use in the spiegel to be delivered to the
Bessemer converter or open hearth furnace. In order to reduce the manganese'

page_text: percentage of the spiegel before it goes to the converter it is first run into a ladle or
other vessel and transferred to a mixing chamber of suitable construction (such as
above described). The spiegel thus tapped from the furnace and with the percentages
of its constituents properly determined will have added thereto preferably in the
mixing chamber such quantities of pig-iron or other iron-silicon alloy either direct 5
from a blast furnace or from a cupola (or both) in order to dilute or reduce the
percentage of manganese and if necessary increase the percentage of carbon and
silicon so as to give the desired percentages of manganese, carbon and silicon in the
final mixture. If the mixture thus obtained by adding pig-iron to the metal from the
spiegel furnace is found to contain the desired percentage of manganese, silicon and 1
carbon it will be tapped from time to time from the mixing chamber and delivered
If it be found,
to the converters at the end of the "blow" in usual manner.
however, that the molten mass of metal within the mixing chamber is still too high
in manganese more pig-iron of the proper silicon content will be added; whereas if
it be found that the inetal within the mixing chamber is too low in manganese,
then additions of spiegel direct from the spiegel furnace or from a cupola and
containing a higher percentage of manganese will be made in order to raise the
manganese percentage of the metal in the mixing chamber to the desired point.
Should the spiegel delivered from the speigel furnace be found to be too high or too
low in the silicon content to give the desired amount of silicon in the mass of metal
within the mixing chamber, then further additions of spiegel containing excess of
manganese will be delivered to the mass within the chamber until the manganese
percentage of the metal within the chamber is raised above the desired point, after
which pig-iron having a proper silicon content will be added so as to dilute the
mixture until the proper percentages of manganese and silicon are obtained.
It is manifest that by this feature of invention, not only is a great saving effected by
avoiding the remelting of the spiegel in a cupola, bnt it becomes possible to change
the character or grade of the spiegel upon very short notice and even between
converter heats. It is manifest that if it is desired to suddenly change the character
of the spiegel that is to be delivered to the charge of a Bessemer converter or open
hearth furnace and to use but a very small quantity of such changed mixture, as for
example, in running a few heats only of the converter or open hearth furnace, then
it would not be necessary to change the character of the entire mass of metal within
the mixing chamber, particularly if the chamber be of large capacity. In such case
a quantity of the spiegel would then be tapped from the mixing chamber into a
suitable ladle and there would be added to the ladle a suitable quantity of molten
pig-iron, or spiegel, or both, sufficient to give to the mass of molten mixture within
the ladle the precise character or grade of spiegel desired for the few heats of the
converter or open hearth furnace that are to be made with such spiegel. Under such
conditions the ladle would then serve as a mixing chamber but manifestly the broad
feature of this part of the invention would be followed because in such ladle, thus
serving as a mixing chamber, the character of the spiegel would be varied by the
addition of molten metal necessary to give the desired grade or character to the
spiegel that was to be added to the converter or open hearth furnace.
In the preferred and most ecconomical practice of the third feature of this invention
by which a much lower and cheaper grade of manganiferous ores can be used, and in
the preferred practice of the fourth feature of the invention which relates to the
mixing of the metallic additions with the smelted spiegel before it is run into the
mixing chamber to insure a more thorough and uniform admixture, the smelting
furnace will be charged in suitable manner with a low grade manganiferous ore, suc
for example, as will give to the product of the smelter a manganese content of sa
from 8 to 12 per cent. The metal from the smelter will be delivered by a suitabl
runner into ladles and by preference will be transported by these ladles to a suitabl
mixing chamber having a capacity sufficient to receive one or preferably several cast
from the spiegel furnace. As the low grade spiegel is thus delivered from the smeltin
furnace there will be gradually added to the metal while in the runner or at th
discharge end of the runner or while in the receiving ladle, a quantity of riche

page_text: spiegel, or ferro-manganese (and if desired, also ferro-silicon or similar iron alloys),
necessary to raise the manganese content and as well also the silicon and carbon or
the like of the low gra le spiegel to the required percentages. These additions of
richer spiegel or ferro-manganese or the like, inty be made in molten condition,
although it is preferable to make such additions in comminuted or lump forin, the
richer spiegel or ferro-manganese being broken to about the size of hickory nuts and
brought to a red-heat and then gradually delivered into the mass of metal from the
blast-furnace. It is preferred also, to make these additions while the metal from the
blast furnace is passing down the runner since thereby a more gradual and uniform
distribution of the additions can be effected and the intimacy of the mixture can be
increased by the agitation incident to the passage of the metal down the runner and
its delivery into the receiving ladle. The charge of metal within the ladle may then
be delivered to the mixing chamber (if a mixing chamber be employed) and there
mixed with pre-delivered charges, and from this mixing chamber portions of the metal
will be tapped from time to time for additions to the charges of the Bessemer
converter or refining chamber. By thus adding the richer spiegel or ferro-manganese
or the like to the low grade before the delivery of the metal to the mixing chamber,
a far more intimate mixture of the additions with the mass of metal is insured than
would be possible if the additions of richer spiegel or ferro-manganese or the like
were made in the mixing chamber, and consequently a much more uniform distribution
of the manganese, silicon and carbon or the like throughout all parts of the mass of
metal within the mixing chamber is obtained. The thorough admixture of the
ad litions of richer spiegel or ferro-manganese or the like with the blast furnace casts,
results not merely from the mechanical agitation of the smelted metal and the
additions made thereto during the delivery into and discharge from the receiving
ladles, but the agitation of the metal within the ladle incident to the generation
of the gases therein during the time that the metal is within the ladle also contributes
materially to the more uniform mixture of the content of manganese, silicon and
When a richer spiegel or ferro-
carbon or the like, throughout the entire mass.
manganese is added to a lower grade spiegel it has been found that there is a tendency
of the metal to stratify, but by making the additions to the low grade spiegel before
it is discharged from the receiving ladle (and preferably before its delivery thereinto)
all danger of this stratifying of the metal is avoided. Preferably the ladle that
receives the charge of spiegel from the smelter will be covered and will be provided
with a gas or oil burner or may have an addition of charcoal, or coke-dust in order
to keep the metal hot in transit from the blast furnace to the mixing chamber (when
a mixing chamber is used), and in order to secure a more intimate mixture within the
ladle it is preferable to insert a bar of wood into the molten metal contained therein,
When the smelted spiegel from
the result being a violent ebullition of the mass.
the blast furnace is delivered to the mixing chamber a further intimacy of the
mixture is secured by reason of the mechanical agitation incident to the discharge of
the metal from the receiving ladle into the mixing chamber and the agitation therein
resulting from the repeated additions of metal to such chamber. The fourth feature
of the invention which consists in delivering to the metal from a smelter while such
5 metal is running into the ladle or while contained in the ladle such additions as will
adapt such metel as a recarburizing addition to a converter charge will be found of
advantage not merely in the production of spiegel from low grade ores in manner
herein described, but will be found applicable also in other connections in which it is
desired to change the character or grade of the recarburizing metal from the smelting
O furnace. Therefore, it is not desired that this feature of the invention be understood
as restricted either to the production of spiegel or to the enrichment of a low grade
spiegel, since plainly this fourth feature of the invention, viz., making the desired
additions to the product of a smelting furnace before it is discharged from the
receiving ladle, can be practiced with advantage irrrespective of the precise character
5 or grade of the metal delivered from the smelter or of the precise grade or character
of chemical composition of the additions, that are made to the furnace product. In
the practice of the invention, so far as the same relates to the addition of richer

page_text: spiegel or ferro-manganese to a low grade spiegel in manner above defined, it i
preferable to make the required additions at a red-heat since the necessity of melting
spiegel or ferro-manganese in a cupola or furnace for this purpose is thereby avoided
this use of solid additions being rendered possible by reason of the uniform distribution
of the additions throughout the mass owing to the additions being made prior t
the discharge of the metal from the ladles.
Instead of transporting the spiegel from a blast furnace to a mixing chamber by
small ladles as above described, the mixing chamber might be dispensed with and a
single ladle employed of suitable construction and capacity to receive the entire
cast from the smelting furnace or to receive several successive casts therefrom. Or
without departing from the spirit of the invention, the metal from the
smelting furnace having received suitable additions of richer spiegel or
ferro-manganese or the like, necessary to adapt the metal for use as a recarburizing
addition to the charge of a Bessemer converter or open hearth furnace, might be
transferred directly from the smelting furnace to the converter or open hearth
furnace. It is manifest that the precise quantity and character of the additions of
richer spiegel, ferro-maganese or the like that should be made to the inetal from the
smelting furnace will depend upon the character of the metal at such time and
upon the percentages of silicon, manganese, carbon, and the like that are called for
by the character or grade of the finished product of the converter or open hearth
furnace. And it is obvious that changes in the precise grade and character of the
spiegel to be delivered to the converter or open hearth furnace can be quickly varied
by variation in the quantity or character of the additions made to the metal from
the smelting furnace. While the third and fourth features of the invention are
primarily designed for the production of a spiegel in manner above defined, it is
inanifest that these features of the invention may be employed in the production of
other metallic alloys suitable as additions to the charges of the Bessenier converter
or open hearth furnace.
Having now particularly described and ascertained the nature of our said invention
and in what manner the same is to be performed, we declare that what we
claim is :-
1. That improvement in the process of manufacturing steel in a Bessemer
converter or open-hearth furnace that consists in first producing spiegel or
ferro-maganese in a smelting furnace and thereafter, without re-melting said spiegel
or ferro-manganese, adding the same to the charge of a Bessemer converter or
open-hearth furnace.
2. The process of producing a metallic alloy suitable as an addition after the refining
operation to the charge of a Bessemer converter or open-hearth furnace, that consists
indelivering molten metal into a suitable mixing chamber and therein adding to
the charge of the mixing chamber a further quantity of molten metal
one or more agents (such as manganese, silicon, carbon or the like) in proper
containing
quantity to give to the mass of metal within the mixing chamber a character that shall
adapt the mixed mass of metal for use as an addition, after the refining operation to the
charge of a Bessemer converter or open-hearth furnace.
3. The process of producing spiegel suitable for use in steel manufacture that
consists in charging a blast furnace with ore so low in manganese as to give to the
product of the furnace a manganese percentage below that desired in the spiegel that is
to be charged into the Bessemer converter or open-hearth furnace, afterwards tapping the
smelted metal from the blast furnace and mixing with said metal after it is discharged
from the blast furnace, a metallic addition containing a sufficient excess of
manganese to adapt the spiegel as a recarburizing addition to the charge of a
Bessemer converter or open-hearth furnace.
4. The process of producing and using a metallic alloy suitable as a recarburizing
addition to the charge of a Bessemer converter or steel refining chamber that consists
in mixing with the smelted metal from the blast furnace before it is discharged from
the receiving ladle suitable metallic additions containing one or more of the agents (such

page_text: as silicon, manganese, carbon or the like) for which said blast furnace product serves as
a vehicle, and thereafter while said metallic alloy is still in the molten condition in
which it is received from the blast furnace (i.e., without re-melting), adding said
alloy to the charge of the Bessemer converter or steel refining chamber after the
refining operation.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicants.