Improvements in the Treatment of Iron and Basic Slag and in Extracting Silicon and Phosphorus.
Year: 1892

page_text: Date of Application, 3rd June, 1892
Complete Specification Left, 15th June, 1892-Accepted, 10th Sept., 1892
PROVISIONAL SPECIFICATION.
Improvements in the Treatment of Iron and Basic Slag and in
Extracting Silicon and Phosphorus.
A communication by BENJAMIN TALBOT, of 222, East Terrace Street,
Chattanooga, Tennessee, United States of America, Manager of Steel Works.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for
Foreign Patent Solicitors, 6 Lord Street, Liverpool and 6 Bank Street, Manchester,
both in the County of Lancaster, and 323 High Holborn in the County of Middlesex,
Civil Engineer, do hereby declare the nature of this invention to be as follows:-
This invention has for its object the obtaining of iron which has in it silicon
and phosphorus and in extracting the silicon and phosphorus therefrom, by an
operation carried on outside of the furnace and without the employinent of
additional fuel for the purpose.
To this end, the molten iron is subjected to a process of filtration through liquid
basic slag, the effect of which is to cause the union of the metalloids and other
impurities with the slag, leaving the iron in a condition of purity, in which condi-
tion it sinks below the slag so that it may be removed and separated either by
tapping it off through a hole at the bottom, tapping it out at the top from under
the slag, or by first removing the slag and thereafter pouring away the iron. The
operation may be carried on in a vessel or apparatus of any suitable character.
The re-action which occurs is very violent and results in the maintenance of a
suitable temperature without the employment of fuel or the application of heat
from an external source. The preferred practice is to draw the molten slag in a
deep body or column into a retaining vessel lined with highly refractory material
and thereafter to pour the molten iron into the slag through which it sinks. The
purified iron is then tapped away at the bottom of the vessel and additional iron
poured through the slag, the operation being carried on either continuously or
intermittingly until the slag becomes inert. The delivery of slag into and from
the vessel may be continuous or intermittent.
Good results may be obtained by pouring the molten metal and molten slag into
the vessel simultaneously, the effect of this action being to cause a thorough
agitation and commingling of the two materials, so that every portion of the iron
is brought into intimate contact with the slag. If complete purification be desired,
so that practically all the impurities will be removed, it is found that the best
results are obtained by subdividing or breaking up the fluid iron into a series of
small streams and allowing it to fall in this form into and through the slag, this
subdivision being attended with an increased exposure of surface to the slag and
resulting in the more rapid completion of the process, by bringing the liquid metal
and liquid slag into contact by a filtration process as herein described. With a
deep column or body of slag, Mr. Talbot is enabled to secure their thorough and
intimate contact in all their parts and thus to ensure a rapidity and uniformity of
purification which cannot be otherwise obtained.
The invention is also applicable in the manufacture of steel which shall contain
an exceedingly small percentage of phosphorus. Acid Bessemer steel is made as
follows
.
Molten pig iron so impure as to render it commercially useless is poured into a
Bessemer converter and the air-blast is forced through it at high pressure. The
oxygen of the blast turns some of the metallic iron to an oxide as it enters the
converter and this oxide eliminates the silicon and carbon from the metal. When
these metalloids have been expelled, the converter is turned down and the blast
ΓΙ

page_text: taken off. The metal is deoxidised by the addition of manganese in the form of
ferro-manganese or spiegel. As any considerable percentage of phosphorus in steel
renders it commercially useless on account of the brittleness which this metalloid
imparts to the metal, and as it is impossible to remove phosphorus from metal by
any acid process, it is therefore necessary that the molten pig iron should contain
less phosphorus than it is desired to have in the finished steel that is used for rail
and other common purposes which is required to have not more than a tenth of one
per cent. of phosphorus; if the steel should contain two tenths it would be worthless.
By this process, it is proposed to take the ordinary quality of steel and convert it
to a higher grade. That is, the metal is used which contains one per cent. of
phosphorus, and the phosphorus to three tenths of one per cent. is eliminated.
It is preferred to instal the process as follows:-
The iron is blown in the usual acid converter, as is done when making ordinary
acid steel. The silicon is eliminated and practically all the carbon, and, as soon as
the flame is perceived to be dropping, which indicates that the metal is nearly
decarbonised, the converter is turned down and the blast taken off. If this metal
were now poured into the casting ladle and manganese added, a fair quality of
steel will be the result. Instead of doing this, a crane is arranged which commands
the Bessemer converter, and, on this crane, a cylindrical or other vessel is suspended,
into which a stated quantity of liquid basic slag has been put. The crane is placed
under the converter and the latter emptied of its metal into the filter which con-
tains the slag, care being taken that no silicious slag is emptied from the converter
into the basic slag. The metal descends through the body of liquid basic slag,
and the remaining traces of silicon and practically all the carbon and phosphorus
are expelled, and the metal is a bath of pure metallic iron. The crane of the
filter which contains the pure metal is swung over the casting ladle, and the metal
is tapped out preferably at the bottom. As the metal is running out, the ferro-
manganese or spiegel is introduced into the casting ladle so that it becomes
deoxidised and is then poured from the casting ladle into ingots. The manganese
is introduced after the filtering process, as the iron oxidising basic slag would have
a tendency to expel manganese from the metal. If Bessemer metal is taken which
contains a high percentage of phosphorus, the vessel is turned down a few seconds
earlier than is done when the metal contains a larger percentage of phosphorus.
This leaves a little more carbon in the metal, causing a much more active reaction
between the slag and molten metal and giving a better chance for the expulsion of
the phosphorus.
When acid steel is made in the Siemens open hearth furnace, the course of
procedure is exactly the same as when it is made in the converter. That is, the
metal is tapped from the furnace, filtered, the phosphorus reduced and then
deoxidised in the casting ladle.
Dated the 2nd day of June 1899
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Patent Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Treatment of Iron and Basic Slag and in 4
Extracting Silicon and Phosphorus.
A communication by BENJAMIN TALBOT, of 222, East Terrace Street,".
Chattanooga, Tennessee, United States of America, Manager of Steel Works.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency. for
Foreign Patent Solicitors, 6 Lord Street, Liverpool and 6 Bank Street, Manchester, 50
both in the County of Lancaster, and 323 High Holborn in the County of
Middlesex,,Civil Engineer, do hereby declare the nature of this invention and

page_text: in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
This invention has for its object the obtaining of iron which has in it silicon and
phosphorus and in extracting the silicon and phosphorus therefrom, by an operation
carried on outside of the furnace and without the employment of additional fuel
for the purpose.
To this end the molten iron is subjected to a process of filtration through liquid
basic slag, the effect of which is to cause the union of the metalloids and other
impurities with the slag, leaving the iron in a condition of purity, in which
condition it sinks below the slag so that it may be removed and separated either by
tapping it off through a hole at the bottom, tapping it out at the top from under
the slag, or by first removing the slag and thereafter pouring away the irou. The
operation may be carried on in a vessel or apparatus of any suitable character.
The re-action which occurs is very violent and results in the maintenance of a
suitable temperature without the employment of fuel or the application of heat
from an external source. The preferred practice is to draw the molten slag in a
deep body or column into a retaining vessel lined with highly refractory material
and thereafter to pour the molten iron into the slag through which it sinks. The
purified iron is then tapped away at the bottom of the vessel and additional iron
poured through the slag, the operation being carried on either continuously or
intermittingly until the slag becomes inert. The delivery of slag into and from
the vessel may be continuous or intermittent.
Good results may be obtained by pouring the molten metal and molten slag into
the vessel simultaneously, the effect of this action being to cause a thorough agita-
tion and commingling of the two materials, so that every portion of the iron is
brought into intimate contact with the slag. If complete purification be desired
so that practically all the impurities will be removed, it is found that the best
results are obtained by subdividing or breaking up the fluid iron into a series of
small streams and allowing it to fall in this form into and through the slag, this
subdivision being attended with an increased exposure of surface to the slag and
resulting in the more rapid completion of the process, by bringing the liquid metal
and liquid slag into contact by a filtration process as herein described.
With a
deep column or body of slag Mr. Talbot is enabled to secure their thorough and
intimate contact in all their parts and thus to ensure a rapidity and umformity of
purification which cannot be otherwise obtained.
The invention is also applicable in the manufacture of steel which shall contain
an exceedingly small percentage of phosphorus. Acid Bessemer steel is made as
follows; molten pig iron so impure as to render it commercially useless is poured
into a Bessemer converter and the air-blast is forced through it at high pressure.
The oxygen of the blast turns some of the metallic iron to an oxide as it enters the
converter and this oxide eliminates the silicon and carbon from the metal. When
these metalloids have been expelled, the converter is turned down and the blast
taken off. The metal is deoxidised by the addition of manganese in the form of
ferro-manganese or spiegel. As any considerable percentage of phosphorus in
steel renders it commercially useless on account of the brittleness which this
metalloid imparts to the metal, and as it is impossible to remove phosphorus from
metal by any acid process, it is therefore necessary that the molten pig iron should
contain less phosphorus than it is desired to have in the finished steel that is used
for rail and other common purposes which is required to have not more than a
tenth of one per cent. of phosphorus; if the steel should contain two tenths it
would be worthless. By this process it is proposed to take the ordinary quality of
steel and convert it to a higher grade. That is, the metal is used which contains
one per cent. of phosphorus, and the phosphorus to three tenths of one per cent. is
eliminated. It is preferred to instal the process as follows: The iron is blown in
the usual acid converter as is done when making ordinary acid steel. The silicon
is eliminated and practically all the carbon, and as soon as the flame is perceived to
be dropping, which indicates that the metal is nearly decarbonised, the converter is

page_text: turned down and the blast taken off. If this metal were now poured into the
casting ladle and manganese added, a fair quality of steel will be the result.
Instead of doing this, a crane is arranged which commands the Bessemer converter,
and on this crane a cylindrical or other vessel is suspended into which a stated
quantity of liquid basic slag has been put. The crane is placed under the converter
and the latter emptied of its metal into the filter which contains the slag, care
being taken that no silicious slag is emptied from the converter into the basic slag.
The metal descends through the body of liquid basic slag and the remaining traces
of silicon and practically all the carbon and phosphorus are expelled, and the
metal is a bath of pure metallic iron. The crane of the filter which contains the
pure metal is swung over the casting ladle, and the metal is tapped out preferably
at the bottom. As the metal is running out, the ferro-manganese or spiegel is
introduced into the casting ladle so that it becomes deoxidised and is then poured
from the casting ladle into ingots. The manganese is introduced after the filtering
process, as the iron oxidising basic slag would have a tendency to expel manganese
from the metal. If Bessemer metal is taken which contains a high percentage of
phosphorus, the vessel is turned down a few seconds earlier than is done when the
metal contains a larger percentage of phosphorus. This leaves a little more carbon
in the metal, causing a much more active reaction between the slag and molten
metal and giving a better chance for the expulsion of the phosphorus.
When acid steel is made in the Siemens open hearth furnace, the course of
procedure is exactly the same as when it is made in the converter. That is, the
metal is tapped from the furnance, filtered, the phosphorus reduced and then
deoxidised in the casting ladle.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondent, I declare that what I claim is-
1. The process of purifying iron which consists in placing in a suitable vessel
a deep column of liquid basic slag, pouring the molten iron downward through the
slag, thereby causing the metalloids and other impurities to combine with the
basic elements of the slag, the reaction liberating heat whereby the slag is
maintained in the fluid state, and finally separating the purified metal from
the slag.
2. The method of purifying iron consisting in bringing liquid molten iron into
contact with liquid basic slag outside of a furnace, the temperature being maintained
by the reaction which occurs, and finalling separating the purified metal and the
slag after the metal has sunk beneath the slag.
Dated this 14th day of June 1892.
WM. P. THOMPSON & Co.,
Agents for the Applicant.