Improvements in the Manufacture of Iron and Steel.
Year: 1889

page_text: Date of Application, 8th Oct., 1889-Accepted, 9th Nov., 1889
CUMI LEID
DIBUITICATION.
Improvements in the Manufacture of Iron and Steel.
I, GEORGE ARCHBOLD residing at 35 Wall Street, New York City, in the County
and State of New York, United States of America, Chemist, 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 :-
It is well known that iron made from certain classes of ores, more especially those
found in the Southern United States, contains such large percentages of phosphorus
or phosphorus and sulphur as to render it unfit for many uses to which the iron can
be applied.
My invention has for its object the elimination of the phosphorus or phosphorus
and sulphur from the metals resulting from the said ores, either in the process of
smelting the ores or in the refining of crude or pig iron and converting it into malleable
iron or steel.
My invention consists in subjecting such ores or the resulting crude or pig iron to
the action of the salts of barium whereby the phosphorus or phosphorus and sulphur is
eliminated therefrom.
In treating the ores 1 make use of an ordinary blast furnace and I add to the
molten mass of metal in the furnace salts of barium, preferably the carbonate of barium
in the form termed Witherite, in the proportion of at least two parts by weight of
barium carbonate to each part of phosphorus and sulphur contained in the molten
mass, such being the equivalent proportions in which the barium carbonate combines
with the phosphorus and sulphur. The amounts of barium carbonate to be added
are easily determined by knowing the analysis of the iron ore and coke used. The
barium carbonate can be distributed in lumps throughout the ore, coke, and limestone
in the furnace, or preferably it may be placed in pulverized form in the tuyeres through
which the air will force it into the mass of molten metal which accumulates in the
lower part of the furnace; or it may be introduced in any other manner which will
bring the requisite proportion of barium carbonate into complete contact with the
melted mass.
In the molten mass the phosphorus and sulphur are in the form of phosphide of
iron and sulphide of iron which readily combine with the barium carbonate forming
barium phosphide and barium sulphide, and these are carried off in the slag, the
purified metal being drawn off as usual. For instance, an iron containing 0.03.
per cent. of phosphorus and a quantity of sulphur, when reduced by the ordinary
process, contains in the pig iron 0.75 per cent. of phosphorus and a corresponding
amount of sulphur and. is unfit for making steel by the ordinary Bessemer process.
But when this metal is subjected to the action of barium carbonate, substantially in
the manner herein set forth, such ore produces pig iron containing only 0.068 per cent.
of phosphorus and a mere trace of sulphur, and it is fit for many uses to which pig
iron containing a larger percentage of phosphorus cannot be applied.
Instead of treating the ore in the process of smelting, the pig or the crude iron
can be refined and converted into malleable iron or steel in any of the usual processes,
as in the cupola, ladle, crucible or converter used in what is generally known as the
Bessemer process. To do this I have found it most convenient and practicable to add.
the salts of barium to the molten metal in the form of powder which may be
supplied to the cupola, ladle, crucible, or converter in any convenient manner, though
it may otherwise be supplied as in the form of lumps. The salts of barium are
added in amount shown by analysis of the iron, to be sufficient at least to com-
pletely combine with all the phosphorous and sulphur; or, if it is desired to retain
some of the phosphorus, the desired proportion of phosphorus can be eliminated by
adding the proper amount of the salts of barium to combine with that proportion of
Price

page_text: phosphorus. The salts of barium combine with the phosphorus and with any sulphur
contained in the molten mass and pass off as a volatile product or in the slag.
While 1 can make use of different salts of barium, as the oxides, nitrate, and
other oxy-salts of barium, I have found that for many reasons the carbonate of barium
is the best. This substance, which is found in nature in the form termed Witherite,
is cheap and easily attainable, and moreover its chemical properties are such that it is
peculiarly adapted to accomplish the desired result.
At the melting point of iron the contained phosphorus and sulphur have a greater
chemical affinity for the barium carbonate than for the iron, and they completely
unite with the barium carbonate as rapidly as contact is effected, not again uniting
with the iron at any temperature ordinarily required in the treatment of the iron.
The other salts of barium do not unite with the phosphorus as readily as the barium
carbonate does, except the oxides of barium, which however are not obtained as readily
as the barium carbonate.
My invention is based on the reaction that when barium carbonate is heated in
contact with carbon and atmospheric or equivalent nitrogen at a temperature of at
least 2200° F. 40 per cent. of the barium is converted into cyanide of barium which
immediately reacts upon the phosphide of iron eliminating the phosphorus, which
unites with the resulting baryta as phosphide of barium, while in this reaction
ferrocyanide of iron is produced and is immediately converted into a refractory
carbide of iron which mixes with the slag.
By the use of my invention I am therefore enabled to produce or refine what is
known as ore or iron high in phosphorus and convert it into iron and steel having
the qualities of iron and steel low in phosphorus.
I have found that if the iron contains a high percentage of silicon, it is sometimes
advantageous to use a certain percentage of barium nitrate in place of a part of
and together with the barium carbonate, and in this way the silicon is also
eliminated.
In some cases the cyanide of barium may be used in place of the carbonate, and
this combines with the phosphorus and sulphur in the molten mass without the prior
reaction of changing the carbonate into the cyanide, but as this form of barium is
more expensive than the carbonate I generally prefer to use the latter.
The results above described may be accomplished to a certain extent by using the
salts of strontium instead of the salts of barium, but not as completely and perfectly
as by thesalts of barium, and I therefore prefer to use these latter salts.
While I have thus described, what I consider to be the most successful ways of
carrying out my invention, I do not wish to limit it to the particular process or
applications of the process herein set forth, as it may be carried out in other ways by
those skilled in the art without materially departing from the principles
thereof.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is ;-
.
The method substantially as herein described of smelting or refining iron ore or
crude or pig iron, which consists in treating it in the presence of the salts of barium.
Dated this Eighth day of October 1889
W. P. THOMPSON & BOULT,
Agents for the Applicant.