IMPROVEMENTS IN THE MANUFACTURE OF STEEL
Year: 1876

page_text: LETTERS PATENT to Julius Baur, of the City of Brooklyn, in the County of
Kings, and State of New York, in the United States of America, but at
present of 23, Southampton Buildings, in the County of Middlesex, for the
Invention of "IMPROVEMENTS IN THE MANUFACTURE OF STEEL."
PROVISIONAL SPECIFICATION left by the said Julius Baur at the Office
of the Commissioners of Patents on the 29th January 1876.
JULIUS BAUR, of the City of Brooklyn, in the County of Kings, and State of
New York, in the United States of America, but at present of 23, Southampton
Buildings, in the County of Middlesex. "IMPROVEMENTS IN THE MANUFACTURE OF
STEEL."
This Invention relates to certain improvements in the manufacture of steel
which I term "chrome steel," that is to say,-
First, to a process whereby chrome ore can be thoroughly and cheaply reduced to
a metallic basis, and ferro-chromium produced of suitable quality for combination
with the steel making iron used for the manufacture of steel.
And, secondly, to a process, by which said ferro-chromium may be combined with
the steel making iron and a steel of of any desired grade and of uniform quality
produced therefrom.
And, thirdly, to improvements in the process described in the Specification of
Letters Patent granted to me, dated August 21st, 1869, No. 2501, of making chrome
steel by the direct mixture of chrome ore with the charge of steel making iron.
In carrying out the first part of my present Invention I combine with the
requisite quantity of pulverized chrome ore the requisite proportion of pulverized
graphite and borax, or a flux containing borax as hereafter described. This mixture
is then placed in a crucible, preferably with a quantity of pure iron to facilitate the
reduction of the chrome ore, and is then subjected to heat in a suitable furnace, until
reduction takes place, when it will be found that the chromium and iron have
been reduced to a metallic basis, and that a solid mass of ferro-chromium has been
produced.
As the quantity of graphite necessary for the proper reduction of the chrome orc
depends on the amount of oxide contained therein, and the quantity of borax or
Price A71

page_text: flux containing borax on the proportion of earthy matters (or gangue), it is obvious
that it is first necessary to test the ore to be reduced, and ascertain its composition,
and then to proportion the quantities of graphite and borax, or borax flux
accordingly.
Taking the chrome ore, I have generally used which contains about 44·48
protoxide of iron, 40-79 oxide of chromium, 2.12 silica, 4.20 alumina, 2.32 lime, and
5 21 magnesia; as an illustration, 1 take 15 lbs. of said chrome ore, about 21 lbs.
graphite, and about 2 lbs. of borax, all finely pulverized and thoroughly mixed;
this mixture I then place in a crucible, and on top of it put 15 lbs. of good inetallic
iron, free from phosphorus and sulphur; I then place the crucible in a suitable
furnace until the reduction is completed, when I obtain about 24 lbs. of ferro-
chromium thoroughly reduced and ready for use. In practice I find it advantageous
to pour the alloy of ferro-chromium into water instead of into a mould in order to
granulate it, as it is more convenient for use in that form; the success of the
reduction depends on the application of a suitable flux, and I have found after many
years experience, and many fruitless trials that borax or a flux containing borax
is necessary, and must be used in about the proportions mentioned to insure the
proper reduction of chrome ore, all other fluxes fail to produce anything but imperfect
results.
The following is an example of a flux containing borax I have used with good
results: Take about 21/, lbs. borax, 2 lbs. silex, and 2 lbs. carbonate of line; pulverize
the whole and reduce at a white heat; the result will be a greyish mass, weighing
about 43/lbs., which I pulverize and use in the same manner as the borax, using
however about 25 per centum more in weight than when using simple borax as a
flux, that is to say, instead of using 2 lbs. of borax in the example given above, I
should use about 2 lbs. of this flux.
The proportions of the flux given above may be varied, and many other com-
binations with borax could be devised, but I find that either pure borax or a flux
of which borax in about the proportion above mentioned is an ingredient is
indispensable to the complete reduction of chrome ore. If materially less borax is
employed in the flux mixture than that above described the result is not so
'satisfactory.
11
The quantity of borax or borax flux required depends upon the amount of
gangue" in the ore, but for chrome ore of the quality above specified I use about
2 lbs., though good results can be produced even when the quantity of borax or flux
containing borax is reduced 25 per cent. below the proportion given above by using
a very high heat, but below those proportions the reduction is imperfect.
When the quantity of borax is increased beyond the amount actually necessary,
that material is wasted, and the excess thereof produces no effect in the reduction
of the metal.
As carbon is necessary to eliminate the oxide from the chrome ore, and as chrome
ore is very refractory, being reducible only at at a high temperature, I have found
that a perfect reduction cannot be obtained by the use of the ordinary carbonaceous
anaterials (such as charcoal, coke, and gas carbon), as they become decomposed or
consumed at too low a temperature, and that graphite is the only carbonaceous
material that is sufficiently refractory to retain its character, so as to produce the
results desired at the heat nccessary for the proper reduction of chrome ore.
The quantity of graphite necessary also depends on the quality of the chrome ore
and especially on the amount of oxides contained therein, but for the chrome ore,
I have described I use about 21/2 lbs. of graphite to every 15 lbs. of chrome ore ns
above; this quantity of graphite might be reduced to about 2lbs., but below that
the result would be doubtful, unless the crucible in which the reduction was effected,
was partially composed of graphite, in which case the chrome ore would cut or wear
the crucible accordingly. I sometimes use as much as 3 lbs. of graphite to 15 lbs.
chrome ore, when I desire for any special purpose to insure the reduction of every
possible particle of chrome in ore of the exact quality of which I am not certain, but

page_text: I know of no chrome ore in the reduction of which any greater amount of graphite
can be usefully employed; if more graphite is placed in the crucible than is necessary
for the thorough reduction of the chromium it will remain unchanged, I prefer to
use graphite of the most refractory character instead of the softer and more easily
decomposed kinds, which besides not being so good in producing the desired effect
will require to be used in increased quantity.
The second part of my Invention consists in combining the ferro-chromium
described above with suitable steel making iron, in such a manner as to ensure the
production of steel of any desired character, perfectly homogeneous and uniform in
quality; the quality of the steel produced being regulated by the proportion of
ferro-chromium or ferro-chromium and carbon used in its manufacturo as illustrated
by the following examples: =
For a steel suitable for ordinary purposes, such as cutlery, edge tools, punches,
cold chisels, stone cutters' tools, and other similar purposes which require great
toughness I take for every 100 pounds of steel making iron about 26 oz. of the ferro-
chromium described above, and about 9 oz. of granulated charcoal (to facilitate the
melting of the iron). I place this charge in a crucible or proper furnace (previously
adding on top of the charge about 6 oz. of oxide of manganese as a flux) until it is
melted, when it is removed and poured into the mould.
For steel of high or hard grade suitable for tools for turning chilled iron and other
substances of extraordinary hardness, mill picks, punches for punching hot metal,
and other purposes requiring steel of great liardness and great resistance to crushing
forces and heat, I take to every 100 lbs. of steel making iron about 52 oz. of the ferro-
chromium described above, and 9 oz. of granulated charcoal, with the same amount
of manganese flux.
For steel such as is desirable for fine springs, taps, dies, and othe purposes
requiring steel of great toughness and elasticity, I take to every 100 lbs. of good
steel making iron about 8 oz. of the ferro-chromium described above, about 8 oz. of
granulated charcoal, with the same amount of manganese flux.
In the above I have based my proportions on the use of good steel making iron
free from sulphur and phosphorus, and containing from 0.20 to 0.22 per centum of
carbon, but if the iron contains more or less carbon the amount of charcoal in the
charge must be increased or reduced in the same proportion. In the same manner
if a harder iron than the one I have specified is used the quantity of ferro-chromium
must be reduced, and if a softer iron is used the quantity of ferro-chromium must
be increased in proportion.
In case there is any reason to suspect the presence of sulphur in the iron or fuel
I add on top of the charge with the manganese flux about 3 oz. of common salt (or
chloride of sodium) to protect the metal from the influence of sulphurous or carbonic
oxide gases, and at the same time to eliminate any sulphur that may be present in
the metal.
In the examples given above I have specified 52 oz. of the ferro-chromium
described above to 100 lbs. of good steel making iron as the quantity necessary to
produce steel for extra high grade, but if it is desired to produce steel still higher it
can be accomplished by increasing the quantity of ferro-chromium, but if the quantity
be unduly increased, say, to the extent of 20 lbs. the steel produced will be fractious
and lose its malleability. When the quantity of ferro-chromium is increased the
quantity of charcoal should be diminished. If, on the other hand, it is desired to
produce a low or homogeneous steel that cannot be hardened the quantity of ferro-
chromium should be reduced, say, as low as 4 oz. to the 100 lbs. of steel making
iron, and as steel of this character is produced at a much higher heat than tool steel
the carbon is not required and should be omitted.
In carrying into effect my said improvements I have found that chrome ore
cannot be reduced properly by the use of graphite in connection with any flux that
does not contain borax, and that no other carbonaceous material will effect a proper
reduction even when borax is used, and that the combination of graphite and borax
is necessary to a proper and thorough reduction of the chrome ore.

page_text: The ferro-chromium as above described is applicable not only to the production
of steel in crucibles, but it can also be successfully employed in the production of
steel in the open hearth or puddling furnace, or by the Bessemer or Martin Siemens
process. In the latter cases I add from 1 to 2 per cent. of the ferro-chromium
as described above to the spiegle eisen with which the decarbonized metal is re-
carbonized. In the puddling furnace the alloy is mixed with the charge of iron,
and the operation conducted in the ordinary manner of puddling, but the per
centage of ferro-chromium must be increased, as a portion of the chrome is by this
process oxidized, and passes off as a flux. I therefore use about double the quantity
of ferro-chromium that would be required in the Bessemer or Martin Siemens process.
The third part of my Invention consists in combining either in crucibles or in
any suitable furnace chrome ore, graphite, or borax (or a flux containing borax, as
above described) with the steel making iron, by which the use of ferro-chromium
previously prepared can be dispensed with, and chrome steel produced at one
operation, and of uniform quality and hardness.
In carrying this part of my Invention into effect I take proper proportions of
chrome ore, graphite, and borax (or a flux containing borax) all finely pulverized
and thoroughly mixed, that is to say; proportions such as are used in the process
previously described. I then place the mixture in the bottom of the crucible or
furnace, and place on top of it the steel making iron to be converted into chrome
steel. The mass is then subjected to heat until fusion takes place, when it will be
found that the chromium has combined with the iron, and that chrome steel has
been produced. This process is not so desirable for the manufacture of fine grades
of chrome steel as the process previously described, a higher temperature being
required to ensure the thorough reduction of the chroine ore. By this process as a
consequence the steel produced is liable to become scamy unless great care is
exercised in its production. For this reason I prefer to confine the use of this
process to the manufacture of homogeneous steel, which must be made at a high
heat, and to the production of cheap steel. This process is not however applicable
to the production of steel in the Bessemer converter or in the puddling furnace.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed by
the said Julius Baur, in the Great Seal Patent Office on the 29th July 1876.
JULIUS BAUR, of the City of Brooklyn, in the County of Kings, and State of
New York, in the United States of America, but at present of 23, Southampton
Buildings, in the County of Middlesex. "IMPROVEMENTS IN THE MANUFACTURE OF
STEEL."
This Invention relates to certain improvements in the manufacture of steel, which
I term "chrome steel," that is to say:-
First, to a process whereby chrome ore can be thoroughly and cheaply reduced
to a metallic basis, and ferro-chromium produced of suitable quality for combination
with the steel making iron used for the manufacture of steel.
And, secondly, to a process by which said ferro-chromium may be combined
with the steel making iron, and a steel of any desired grade and of uniform quality
produced therefrom.
And, thirdly, to further improvements in the process described in the Specifi-
cation of Letters Patent granted to me, dated August 21st 1869, No. 2501, of
making chrome steel by the direct mixture of chrome ore with the charge of steel
making iron.
In carrying out the first part of my present Invention I combine with the
requisite quantity of pulverized chrome ore the requisite proportion of pulverized
graphite and borax or a flux containing borax, as herein-after described. This
mixture is then placed in a crucible, preferably with a quantity of pure iron, to

page_text: facilitate the reduction of the chrome ore, and is then subjected to heat in a suitable
furnace until reduction takes place, when it will be found that the chromnium and
iron have been reduced to a metallic basis, and that a solid mass of ferro-chromium
has been produced.
As the quantity of graphite nesessary for the proper reduction of the chrome ore
depends on the amount of oxide contained therein, and the quantity of borax or flux
containing borax on the proportion of earthy matters (or gangue) it is obvious that
it is first necessary to test the ore to be reduced, and ascertain its composition, and
then to proportion the quantities of graphite and borax or borax flux accordingly.
Taking the chrome ore, I have generally used which contains about 44-48 pro-
toxide of iron, 40.79 oxide of chromuim, 2.12 silica, 4·20 alumina, 2.32 lime,
and 5.21 magnesia. As an illustration I take 15 lbs. of said chrome ore, about
2 lbs. graphite, and about 2 lbs. of borax, all finely pulverized and throughly
mixed; this mixture I then place in a crucible, and on top of it I put 15 lbs. of
good metallic iron, free from phosphorous and sulphur; I then place the crucible in
a suitable furnace until the reduction is completed, when I obtain about 24 lbs.
of ferro-chromium thoroughly reduced and ready for use. In practice I find it
advantageous to pour the alloy of ferro-chromium into water instead of into a
mould in order to granulate it, as it is more convenient for use in that form. The
success of the reduction depends on the application of a suitable flux, and I have
found after many years experience and many fruitless trials of various materials
that borax, or a flux containing borax, is necessary and must be used in about the
proportions mentioned to insure the proper reduction of chroine ore; all other fluxes
fail to produce anything but imperfect results.
The following is an example of a flux containing borax I have used with good
results: Take about 21 lbs. borax, 2 lbs. silex, and 2 lbs. carbonate of lime; pul-
verize the whole and reduce at a white heat, the result will be a greyesh mass
weighing about 4 lbs., which I pulverize and use in the same manner as the borax,
using however about 25 per centum more in weight than when using simple
borax as a flux, that is to say, instead of using 2 lbs. of borax in the example
given above, I should use about 21/2 lbs. of this flux.
The proportions of the flux given above may be varied and other combinations
with borax may be used, but I find that either pure borax or a flux of which borax
in about the proportion above-mentioned is an ingredient is indispensable to the
complete reduction of chrome ore. If materially less borax is employed in the
flux mixture than that above described the result is not so satisfactory.
The quantity of borax or borax flux required depends upon the amount of
gangue" in the ore, but for chrome ore of the quality above specified I use about
2 lbs., though good results can be produced even when the quantity of borax or
flux containing borax is reduced 25 per cent. below the proportion given above by
using a very high heat, but below those proportions the reduction is imperfect.
When the quantity of borax is increased beyond the amount actually necessary
that material is wasted, and the excess thereof produces no effect in the reduction
of the metal.
As carbon is necessary to climinate the oxide from the chrome ore, and as chrome
ore is very refractory, being reducible only at a high temperature I have found
that a perfect reduction cannot be obtained by the use of the ordinary car-
bonaceous materials (such as charcoal, coke, and gas carbon), as they become
decomposed or consumed at too low a temperature, and that graphite is the only
carbonaceous material that is sufficiently refractory to retain its character so as
to produce the results desired at the heat necessary for the proper reduction of
chrome ore.
The quantity of graphite necessary also depends on the quality of the chrome
ore, and especially on the amount of oxides contained therein, but for the chrome
ore I have described I use about 21 lbs. of graphite to every 15 lbs. of chrome ore
as above; this quantity of graphite night be reduced to about 2 lbs., but below that

page_text: the result would be doubtful unless the crucible in which the reduction was effected
was partially composed of graphite, in which case the chroine ore would cut or
wear the crucible accordingly. I sometimes use as much as 3 lbs. of graphite
to 15 lbs. chrome ore when I desire for any special purpose to insure the reduc-
tion of every possible particle of chrome that may be present in any ore of the
exact quality of which I am not certain, but I know of no chrome ore in the
reduction of which any greater amount of graphite can be usefully employed. If
more graphite is placed in the crucible than is necessary for the thorough reduction
of the chromium it will remain unchanged. I prefer to use graphite of the most
refractory character instead of the softer and more easily decomposed kinds, which
besides not being so good in producing the desired effect will require to be used in
increased quantity.
The second part of my Invention consists in combining the ferro-chromium pro-
duced as above described with suitable steel making iron in such a manner as to
ensure the production of steel of any desired character perfectly homogeneous and
uniform in quality. The quality of the steel produced being regulated by the pro-
portion of ferro-chromium or ferro-chromium and carbon used in its manufacture as
illustrated by the following examples :-
For a steel suitable for ordinary purposes, such as cutlery, edge tools, punches, cold
chisels, stone cutters' tools, and other similar purposes which require great toughness,
I take for every 100 lbs. of steel making iron about 26 oz. of the ferro-chromium
described above, and about 9 ounces of granulated charcoal (to facilitate the melting
of the iron); I place this charge in a crucible or proper furnace (previously adding
on top of the charge about 6 ounces of oxide of manganese as a flux) until it is
melted, when it is removed and poured into the mould.
For steel of high or hard grade suitable for tools for turning chilled iron and
other substances of extraordinary hardness, mill picks, punches for punching hot
metal, and other purposes requiring steel of great hardness and great resistance to
crushing forces and heat I take to every 100 lbs. of steel making iron from about
52 ounces to 64 ounces of the ferro-chromium described above, and 9 ounces of
granulated charcoal with the same amount of manganese flux.
For steel such as is desirable for fine springs, taps, dies, and other purposes
requiring steel of great toughness and elasticity I take to every 100 lbs. of good
steel making iron about 8 ounces of the ferro-chromium described above, and about
8 ounces of granulated charcoal with the same amount of manganese flux.
In the above I have based my proportions on the use of good steel making iron
free from sulphur and phosphorous, and containing from 0.20 to 0.22 per centum of
carbon, but if the iron contains more or less carbon the amount of charcoal in the
charge must be increased or reduced in the same proportion. In the same manner
if a harder iron than the one I have specified is used the quantity of ferro-chromium
must be reduced, and if a softer iron is used the quantity of ferro-chromium must
be increased in proportion.
In case there is any reason to suspect the presence of sulphur in the iron or fuel I
add on top of the charge with the manganese flux about 3 ounces of common salt (or
chloride of sodium) to protect the metal from the influence of sulphurous or carbonic
oxide gases, and at the same time to eliminate any sulphur that may be present in
the metal.
In the examples given above I have specified 52 oz. of the ferro-chromium described
above to 100 lbs. of good steel making iron as being about the quantity necessary
to produce steel of extra high grade, but if it is desired to produce steel still higher
it can be accomplished by increasing the quantity of ferro-chromiuin, but if the
steel making iron should contain only 005 of carbon the amount of ferro-chromium
added thereto may be increased to, say, 30 lbs., but if the quantity should be still
further and unduly increased the steel produced will be fractious and lose its
malleability when the quantity of ferro-chromium is increased the quantity of
charcoal should be diminished. If on the other hand it is desired to produce a low

page_text: or homogeneous steel that cannot be hardened the quantity of ferro-chromium
should be reduced, say, as low as 4 ounces to the 100 lbs. of steel making iron, and
as steel of this character is produced at a much higher heat than tool steel the carbon
is not required and should be omitted.
In carrying into effect my said improvements it is necessary to bear in mind the
importance of the discovery I have made that chrome ore cannot be reduced
properly by the use of graphite in connection with any flux that does not contain
horax, and that no other carbonaceous material will effect a proper reduction even
when borax is used, and that the combination of graphite and borax is necessary
to a proper and thorough reduction of the chrome ore.
The ferro-chromium as above described is applicable not only to the production
of chrome steel in crucibles but it can also be successfully employed in the pro-
duction of steel in the open hearth or puddling furnace, or by the Bessemer or
Martin Siemens' process. In the latter cases I add from 1 to 2 per cent. of the
ferro-chromium as described above to the spiegel eisen with which the decarbonized
metal is recarbonized. In the puddling furnace the alloy is mixed with the charge
of iron and the operation conducted in the ordinary manner of puddling, but the
per centage of ferro-chromium must be increased as a portion of the chrome is by
this process oxidized and passes off as a flux. I therefore use about double the
quantity of ferro-chromium that would be required in the Bessemer or Martin
Siemens' process.
The third part of my Invention consists in combining either in crucibles or in
any suitable furnace chrome ore, graphite, and borax (or a flux containing borax as
above described) with the steel making iron, by which the use of ferro-chromium
previously prepared can be dispensed with and chrome steel produced at onc
operation and of uniform quality and hardness.
In carrying this part of my Invention into effect I take proper proportions of
chrome ore, graphite, and borax (or a flux containing borax), all finely pulverized
and thoroughly mixed, that is to say, proportions such as are used in the process
previously described; I then place the mixture in the bottom of the crucible or
furnace, and place on top of it the steel making iron to be converted into chrome
steel; the mass is then subjected to heat until fusion takes place when it will be
found that the chromium has combined with the iron and that chrome steel has
been produced. This process is not so desirable for the manufacture of fine grades
of chrome steel as the process previously described, a higher temperature being
required to ensure the thorough reduction of the chrome ore; by this process as a
consequence the steel produced is liable to become seamy unless great care is
exercised in its production. For this reason I prefer to confine the use of this
process to the manufacture of homogeneous steel, which must be made at a high
heat, and to the production of cheap steel. I have found however that this process
is not applicable to the production of steel in the Bessemer converter or in the
puddling furnace otherwise than in the manner proposed to be carried into effect in
a Provisional Specification filed by me on January 31st, 1876. The proportions of
chromium to the steel making iron, and of graphite and borax (or flux containing
borax) to the chrome ore remain the same as in the process previously described,
due allowance of course being made for the iron used in the preparation of the
|ferro-chromium, as above described.
Having thus described the nature of my said Invention, and the mode in which
the same is carried into effect, I would have it understood that what I claim and
desire to secure by Letters Patent is,
-
First. The use of compound composed of chrome ore, graphite, and borax (or a
flux containing borax) in the production of an alloy suitable for the manufacture of
chrome steel, substantially as and for the purpose specified.
Second. The combination of the said alloy in about the proportions indicated
with steel making iron and the manufacture thereby of chrome steel, as herein
described.

page_text: Third. The manufacture of chrome steel in one process by mixing in the crucible
or furnace graphite and borax (or à flux containing. borax), and chrome ore with
the steel making iron to be converted into chrome steel, substantially as described.
In witness whereof, I, the said Julius Baur, have hereunto set my hand
and seal. this. Twenty-seventh day of July, in the year of our Lord One
thousand eight hundred and seventy-six.
כזד בד
JULIUS BAUR. (L.S.)