IMPROVEMENTS IN REFINING CAST IRON FOR FOUNDRY. PURPOSES, AND IN THE PRODUCTION OF WROUGHT IRON AND STEEL
Year: 1870

page_text: LETTERS PATENT to James Henderson, of New York, in the United
States of America, Engineer, for the Invention of "IMPROVEMENTS IN
REFINING CAST IRON FOR FOUNDRY. PURPOSES, AND IN THE PRODUCTION OF
WROUGHT IRON AND STEEL."
Sealed the 5th of May 1871, and dated the 8th November 1870.

page_text: unto me, my executors, administrators, and assigns, Her Royal Letters
Patent for the same, and have made solemn Declaration that I am
the true and first Inventor thereof.
NOW KNOW YE, that I, the said James Henderson, do hereby
declare that the following Complete Specification, under my hand and
seal, fully describes and ascertains the nature of the said Invention, and
in what manner the same is to be performed, in and by the following
statement:—
This Invention of improvements in refining cast iron for foundry
purposes, and in the production of wrought iron and steel, relates to the
removing of the silicon, sulphur, phosphorus, and carbon from crude
cast iron by means of the application to the iron, substantially in the
modes herein-after set forth, of substances containing or capable of
evolving fluorine in combination with other substances. The fluorine in
the form of fluor spar or of any other fluoride may be employed, either
in combination with volatile or liquid substances containing or capable
of evolving oxygen, or in combination with such substances, and also
with nitrates or other salts of the alkalies, or any other solid substances
containing or capable of evolving oxygen, or containing or capable of
evolving acids which will liberate fluorine from the fluorides, so that it
may act upon the silicon in the crude iron. When applying the fluor
spar or other fluoride in combination with the volatile substances referred
to, I inject the fluor spar into and among the liquid crude iron in
connection with the volatile substances, which latter I also prefer to
introduce in blasts or currents. This I usually do during the first three
to five minutes of the operation, and in such a manner as will insure a
constant and regular supply of the fluorspar or other fluoride with the
blast of the volatile agents.
""
The operation may be performed in any vessel, furnace, apparatus, or
converter, whether fuel be or be not used therein. I, however, prefer to
employ the kind of converter generally used in the "Bessemer process,'
in which the blast is applied at the bottom or sides of the apparatus, or
in any other manner in which the purifying gases or agents may be
caused to act from the bottom or lower portion of the metal upwards;
but any other apparatus in which the same results can be obtained will
answer the purpose. The fluor spar or other fluoride should be reduced
to a finely divided state, and in applying it in combination with air or

page_text: other volatile agent I generally prefer to introduce it into the blast pipe
or passage leading into the converter or other apparatus from the blast
machine or other reservoir of the air or of such other volatile agent as
may be employed, the object being, to cause it to be conveyed into the
converter. or vessel with the air or other agent; but it may be introduced
into the converter in any other suitable manner, provided it be introduced
with the air, or other agent.. The proportions of the fluor spar or other
fluoride should be such as will suffice to remove the silicon from the
crude iron, that is to say, about 39 to 45 parts by weight of fluor spar to.
every 14 parts by weight of the silicon contained in the crude iron..
When the fluor spar or other fluoride is introduced in the manner.
described into the converter or other receptacle of, the molten iron and
comes into contact with the latter it instantly melts and evolves gases,
which combine with the silicon and remove it from the iron, while the
phosphorus is eliminated, by combining with the metallic base of the
fluoride, which becomes oxidized by the oxygen of the air or other
volatile agent. At the same time the oxygen of these agents combines
with and removes the carbon. Any desired proportion of the carbon
may be taken from the crude iron, so that the product may be adapted
either to form refined iron for castings, or to form steel; or all the
carbon may be removed, so as to make the product wrought iron. The
character of the product, will be, determined by the amount of oxygen
introduced into the converter, and also by the amount of carbon con-
tained in the iron, and it will of course vary according to the proportion
of the carbon which the operator wishes to remove. The volatile agents
which are generally to be employed are air, steam, superheated, or
otherwise,, and oxygen, or hydrogen gas, and they may be employed
singly or together, and either with or without nitrates or other alkaline
salts, the latter being used to effect the removal of sulphur from the
iron when it is in excess, and when thus employed they should be in
the proportion of about two parts by weight to every one part of the
sulphur, and should be injected into the converter with the blasts of air
or other volatile agent after the fluoride has been introduced. Oxide of
manganese may also be employed to remove sulphur. When used it
should preferably be in the proportion of two parts by weight to one of
sulphur, and should be introduced into the converter after the fluoride
has been injected. If manganese be not present in the iron treated the
oxide of manganese may be employed to remove, silicates from the iron.
.

page_text: When used for this purpose a proportion equal to about two parts by
weight of oxide of manganese to one part by weight of the silicates will
generally answer, and the oxide should be introduced after the fluoride.
If both sulphur and silicates are present in the iron the proportion of the
oxide of manganesc may be increased in the ratio of four parts of the
oxide of manganese to every two parts in the aggregate of sulphur and
silicates. Or orcs of chromium or titanic iron ores may be employed in
similar proportions, and in the same manner as the oxide of manganesc
to remove silicates from the crude iron, but crude iron which contains
chromium will not requiro the use of agents to remove silicates. The
fluor spar or other fluoride may also be applied to the crude iron by using
it in the form of a lining for the converter or other vessel. In this case
also the air or other volatile agent is employed, and I generally prefer
to introduce the latter around the bottom and sides of the vessel where
the blasts or currents of air enter, in order that the fluor spar or other
fluoride may be instantly acted upon by the ox-oxidizing agents contained
in the blast, and may then react upon the silicon of the iron. When
applying the fluor spar or other fluoride in this manner I find it pre-
ferable to first place in the converter over the ordinary silicious lining a
thin supplemental lining of oxides, or of cast iron to protect the silicious
lining from any injurious effects from the fluor spar. For this supple-
mental lining I prefer desiliconized cast iron produced by my hercin
described process, or spiegel eisen, the latter being specially preferable
for the purpose of removing silicates when the iron to be treated does
not contain chromium or manganese. For removing silicates I also
sometimes in forming the lining of fluor spar or other fluoride mix with
the fluor spar, oxides of manganese, or of chromium, or titanium in the
same proportions as before stated.
Crude iron in which chromium, tungsten, or manganese are present
may be freed from silicon for foundry purposes or to be adapted for
recarburizing agents by being run into reverberatory furnaces or other
apparatus in which fuel is used when such furnaces are provided with
such a lining of fluor spar, as described, inasmuch as chromium, tungsten,
or manganese in the crude iron will react with the fluorspar or other
fluoride upon the silicon, and remove it in the same manner and with
the same results as when oxygen is employed with the fluorspar. When
thus used with chromium, tungsten, or manganese the fluor spar lining

page_text: should be of sufficient thickness to serve not only as a lining, but also
to react upon the chromium, tungsten, or manganese in the iron, or it
may be of only sufficient thickness to remove the silicon. If it be
desired to remove- more of the carbon, chromium, tungsten, or manga-
nese than an equal weight of the silicon in the iron oxidizing agents;
preferably the oxide of iron, should also be applied to the iron in vessels
which are provided with the fluor spar lining, or the metal may be
partially treated in such vessels, and the operation may then be com-
pleted in any of the processes used for the production of wrought iron
or steel. Instead of employing the fluor spar or other fluoride as a lining
it may be applied in furnaces or vessels in which fuel is used for the
treatment of metal containing chromium, tungsten, or manganese, by
granulating the metal and mixing the fluor spar in a powdered state
with it. When the granulated metal melts the fluorine of the fluor spar
will react with the chromium, tungsten, or manganese upon the silicon
and remove it. Or when iron is melted in a cupola furnace with ores
containing chromium, tungsten, manganesc, or titanium, the fluor spar
may be applied at the tuyeres, or as a lining or covering for the hearth
or bottom of the furnace, for the purpose of producing a refined iron for
castings.
If steel is desired, so that more carbon needs to be removed, oxides
may be mixed with the fluor spar and applied to the bottom of the hearth
of the cupola or other furnace or receptacle.
This last-mentioned method of application of the fluor spar or other
fluoride and the oxides is also adapted to iron in which chromium,
tungsten, manganese, or titanium are not present when the product
desired is steel or cast iron freed from silicon. The proportion of fluor
spar for these purposes should be sufficient to eliminate the silicon in
the form of fluoride of silicon, and may be about as herein-before
given, that is to say, about 39 to 45 parts by weight to every 14 parts
by weight of the silicon. The oxides also if used should be in about
the proportions above stated, namely, two parts by weight of oxides to
one part by weight of the fluoride used. But when it is desired to
remove sulphur, phosphorus, or carbon from the crude metal, so as to
form steel, the quantity of the oxides should be increased until they
cqual about eight parts by weight to every six parts by weight of the
sulphur, phosphorus, or carbon sought to be removed, assuming per-

page_text: oxide of iron to give off, say, thirty per cent. of oxygen when in presence
of molten crude iron, and the fluoride should preferably be increased to
about half by weight the quantity of the oxides..
Still another mode in which the fluor spar or other fluoride may be
used with great benefit is as a lining, covering, or coating for vessels or
receptacles for melted crude iron in which fuel is not present, and in
which no decarbonization of the iron is effected by volatile agents, as,
for example, in pig beds, moulds, or chills into which melted iron is run-
from blast, cupola, or melting furnaces. In thus employing the fluoride
I prefer to mix with it water or crude or refined petroleum, or other
hydrocarbon, so that the fluoride shall be moistened, and to apply it in
this condition to the bottom or sides of the pig bed, mould, or chill, and
then immediately run it into the mould or other receptacle, where-
upon gases will at once be generated, which will purify the iron from
silicon. In this method of application oxide of iron or other suitable
substance containing or capable of evolving oxygen may be used under-
neath the fluor spar, the oxide being preferably moistened with water,
and the fluor spar with some hydrocarbon. As soon as the melted iron
comes in contact with the fluoride and hydrocarbon an intense heat
will be produced, which will cause the water mixed with the oxide to
evaporate and form vapor. This vapor will mingle with the vapor from
the hydrocarbon and the fluorine from the fluoride, and will act upon
the iron and eliminate from it its impurities. When thus employing the
fluoride I usually line the vessel or mould with it to a thickness of from
one-eighth to one-quarter of an inch, and when the oxides are also used
they should be applied in a thickness of one-half inch to one inch.
In reference to the employment of fluor spar for treating in the modes
herein mentioned iron which contains chromium, tungsten, or manga-
nese, I desire it to be understood that I make no claim to the use of
fluor spar or other fluoride alone when applied in a furnace as a "fettling"
for the treatment of irons which do not contain these elements.
My Invention, so far as relates to the application of fluor spar alone,
consists in the use of it with irons containing chromium, tungsten, or
manganese, as these elements, as I have herein-above stated, in their
reactions with the fluorido upon the iron will take the place entirely or
to a great extent of oxygen, and produce the same results. It is also
proper to mention that in place of using the fluorspar or other fluoride

page_text: as a lining for furnaces, I may apply it by simply throwing it in,
preferably in a state of powder, upon the bottom of the furnace, or
into a mould, chill, or other receptacle for molten iron, but when thus
used the fluorspar or other fluoride should be permitted to become viscid
before the melted iron is run into the furnace or mould.