AN IMPROVED METHOD OR PROCESS FOR REMOVING SULPHUR, PHOSPHORUS, AND OTHER IMPURITIES FROM IRON, STEEL, AND OTHER METALS
Year: 1868

page_text: LETTERS PATENT to Charles Denton Abel, of No. 20, Southampton
Buildings, Chancery Lane, in the County of Middlesex, Patent
Agent, for the Invention of "AN IMPROVED METHOD OR PROCESS FOR
REMOVING SULPHUR, PHOSPHORUS, AND OTHER IMPURITIES FROM IRON, STEEL,
AND OTHER METALS."-A communication from abroad by John Francis
Bennett, of Pittsburgh, Pennsylvania, United States of America.
Sealed the 30th June 1868, and dated the 7th January 1868.
PROVISIONAL SPECIFICATION left by the said Charles Denton Abel
at the Office of the Commissioners of Patents, with his Petition,
on the 7th January 1868.
I, CHARLES DENTON ABEL, of No. 20, Southampton Buildings,
Chancery Lane, in the County of Middlesex, Patent Agent, do hereby
declare the nature of the said Invention for "AN IMPROVED METHOD OR
PROCESS FOR REMOVING SULPHUR, PHOSPHORUS, AND OTHER IMPURITIES FROM
IRON, STEEL, AND OTHER METALS," to be as follows:-
This Invention consists in an improvement in the manufacture of iron
and steel by what is known as the "pneumatic process" (by which is
meant the blowing of a stream or current of gas or combination of gases,
whether atmospheric air or other gaseous mixtures, into the 'molten
metal), the object being to carry off the sulphur, phosphorous, and other
impurities from the metal, which are not removed by that process as

page_text: ordinarily conducted, and the means by which it is effected being the
forcing of a current or stream of carbonic acid gas either with or
without atmospheric air through the molten metal, whereby the
impurities, such as silicon, carbon, sulphur, phosphorus, and manganese,
are eliminated by the successive combination of these substances
with the oxygen of the carbonic acid.
The present improvement may be used with apparatus such as is
employed by Bessemer and others who employ atmospheric air, and
when so used the desired result is effected while the metal remains in
the "converter," and without subjecting it to a process of reheating.
Pig metal or crude iron which results from the process of deoxydizing
the iron ore by means of a blast furnace is highly carbonized iron, with
which are mingled silicon, sulphur, phosphorus, and other impurities.
The "atmospheric" pneumatic process consists in the removal of the
excess of carbon from the metal by subjecting it while in a molten
condition to the direct action of an atmospheric blast for the purpose
of burning out the carbon without the use of separate fuel for sup-
porting combustion and producing the requisite heat. The melted crude
iron is poured into a receiver or converter at a temperature of about
3000° Fahrenheit, and a blast of atmospheric air at a pressure of about
20 lbs. to the square inch is forced through the melted metal, entering at
or near the bottom of the converter and permeating the mass of molten
metal therein. The mechanical effect of the passage of air through
the metal is to produce violent ebullition and commotion, and the
chemical effect is that the oxygen of the air unites with the carbon
in the iron, generating a great increase of heat and causing a vivid
combustion; the carbon of the iron serving, together with a portion of
the iron, as the fuel, and the carbon being thus burned out and thus
thereby removed. During this process, which ordinarily takes about
sixteen minutes, the heat of the metal rises rapidly to about 5000°
Fahrenheit, and as soon as the carbon is all consumed the blast of air
is stopped, as otherwise a rapid oxydation of the metal would ensue.
This process which is successfully employed in the manufacture of steel
from crude iron does not effect the removal of the sulphur and phos-
phorus which are eliminated, if at all, by a subsequent and distinct
operation.
:
By the present Invention it is proposed to effect the removal of the
sulphur and phosphorus from the iron while it is yet in the converter

page_text: and before it has been allowed to cool, by means of carbonic acid gas,
either applied as a separate blast immediately on the the cessation of
the atmospheric blast in the pneumatic process, or by combining
carbonic acid gas with the atmospheric air in that operation.
When the improved process is applied as a part of the atmospheric
pneumatic (or so-called "Bessemer") process, this latter process is first
carried on as usual in the converter, which is arranged so as to be
capable of communicating both with an air blast and a vessel or gas
holder containing carbonic acid gas; when the process of decarboniza-
tion is about completed, or very nearly so, the blast of atmospheric air
is stopped, and a blast of carbonic acid gas is forced into the converter:
After this has continued a short time, say half a minute, the blast is
again changed, and atmospheric air is introduced for about fifteen
seconds, after which the operation is complete. The air and carbonic
acid gas being introduced through the same pump and inlet pipes to
the converter, the purity of each blast is insured by tilting the converter
just before changing the blast so as to allow the changed blast to pass
through the converter without entering the metal, until all traces of the
former blast have disappeared. The requisite carbonic acid gas for
this process may be produced either by the action of muriatic acid on
limestone, or in a less pure state by the perfect combustion of car-
bonaceous matter with air, and the gas be stored up in a gas holder.
The result which is accomplished by the improved process may be
briefly stated thus: -The blast of atmospheric air being continued
through the molten iron until nearly all trace of carbon has dis-
appeared, on the introduction of the carbonic acid gas a chemical
union is formed between the two equivalents of oxygen and the
sulphur present in the iron, forming sulphurous acid which passes
off as gas, depositing the carbon thereby set free, which may be
expressed thus: CO,+S=SO, + C. A similar result takes place
in respect to phosphorus, present as an impurity in the iron,
the oxygen of the carbonic acid combines with the phosphorus,
evolving acid gases of the phosphorus, and depositing carbon, thus
2 CO, + PPO, + 2 C, and carbon is deposited. This deposit of
free carbon may be left in the iron, if preferred, in the manufacture of
steel, or it may be burned out after the sulphur and phosphorus are
removed by a repetition of the atmospheric blast for a few seconds, as
before stated. The oxygen of the carbonic acid gas will also combine

page_text: with the iron forming ferrous acid, thus: C 0, + Fe = 2 Fe 0 + C, the
formation of the protoxide of iron setting free and depositing the carbon.
While the blast of carbonic acid gas is passing through the molten iron
the temperature of the metal will fall somewhat, losing about one-
fourth of the additional heat gained during the passage of the atmo-
spheric blast. This, however, is rather an advantage than otherwise, as
it is found that by the atmospheric pneumatic process the iron is
rendered almost too fluid by the extreme heat. If preferred the carbonic
acid gas may be heated before entering the converter.
A modification of the process described consists in allowing a small
proportion of carbonic acid gas to enter the blast cylinder together with
the air, and thus subjecting the molten crude iron to a combined blast
of atmospheric air and carbonic acid gas; by this means the impurities
are removed during the process of decarbonization.
Other gases or
fluids may also be introduced together with the carbonic acid gas, as
may be desired.
I do not wish to confine myself to the exact mode of introducing
the carbonic acid gas herein-before described, nor to the use of any
particular apparatus, as this may be modified. If the improvement is
applied to the purification of molten iron without the previous use of
an atmospheric blast passed through it, it will be necessary to apply
heat to the vessel containing the molten metal in order to keep it in
the necessary fluid condition, or the gas may be generated between
the blowing cylinder and the converter, and forced into the converter by
means of the atmospheric blast, or by a separate blowing cylinder.
The improved process of removing impurities from iron in a molten
condition by means of a stream or blast of carbonic acid gas is also
applicable to puddling and boiling furnaces, the stream of carbonic acid
gas in this case being introduced by dipping the tuyere which conducts
the blast into the hearth of the working chamber; it is also applicable
to blast furnaces by introducing a stream of carbonic acid into the
molten metal in the hearth, while at the same time the process of
deoxydation of the ore is carried on higher up by means of the ordinary
atmospheric blast in the usual way. Carbonic acid gas may also be
used with advantage in removing sulphur and other impurities from
tho sulphurets of copper, zinc, nickel, and other metals by passing it as
a blast or current through the metals when in a molten state.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Charles Denton Abel in the Great Seal Patent
Office on the 6th July 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
DENTON ABEL, of No. 20, Southampton Buildings, Chancery Lane, in
the County of Middlesex, Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Seventh day of January, in the year
of our Lord One thousand eight hundred and sixty-eight, in the thirty-
first year of Her reign, did for Herself, Her heirs and successors, give
and grant unto me, the said Charles Denton Abel, Her special licence,
that I, the said Charles Denton Abel, my executors, administrators,
and assigns, or such others as I, the said Charles Denton Abel, my.
executors, administrators, and assigns, should at any time agree with,.
and no others, from time to time and at all times thereafter during
the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for "AN
IMPROVED METHOD OR PROCESS FOR REMOVING SULPHUR, PHOSPHORUS, AND OTHER
IMPURITIES FROM IRON, STEEL, AND OTHER METALS," a communication to ne
from abroad by John Francis Bennett, of Pittsburgh, Pennsylvania,
United States of America, upon the condition (amongst others) that I,
the said Charles Denton Abel, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and
seals, should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Charles Denton Abel, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement thereof, reference being had to the accom-
panying Sheet of Drawings, and to the figures and letters marked
thereon, that is to say :-
This Invention consists in an improvement in the manufacture of iron
and steel by what is known as the pneumatic process, by which is meant

page_text: the blowing of a stream or current of gas or combination of gases,
whether atmospheric air or other gases or gaseous mixtures, into the
molten metal, the object being to carry off the sulphur, phosphorus,
and other impurities from the metal which are not removed by that
process as ordinarily conducted, and the means by which it is effected
being the forcing of a current or stream of carbonic acid gas either with
or without atmospheric air through the molten metal, whereby the
impurities, such as silicon, carbon, sulphur, phosphorus, and manganese
are eliminated by the successive combination of these substances with
the oxygen of the carbonic acid.
The present improvements may be used with apparatus such as is
employed by Bessemer and others who employ atmospheric air, and
when so used the desired result is effected while the metal remains in
the converter and without subjecting it to a process of reheating. Pig
metal or crude iron which results from the process of deoxydizing the
iron ore by means of a blast furnace is highly carbonized iron with which
are mingled silicon, sulphur, phosphorus, and other impurities.
The atmospheric pneumatic or "Bessemer process consists in the
removal of the excess of carbon from the metal by subjecting it while in
a molten condition to the direct action of an atmospheric blast for the
purpose of burning out the carbon without the use of separate fuel for
supporting combustion and producing the requisite heat. The melted
crude iron is poured into a receiver or converter at a temperature of
about 3000° Fahrenheit, and a blast of atmospheric air at a pressure of
about 20 lbs. to the square inch is forced through the melted metal,
entering at or near the bottom of the converter and permeating the mass
of molten metal therein. The mechanical effect of the passage of air
through the metal is to produce violent ebullition and commotion, and
the chemical effect is that the oxygen of the air unites with the carbon
in the iron, generating a great increase of heat and causing a vivid com-
bustion, the carbon of the iron serving together with a portion of the
iron as the fuel, and the carbon being thus burned out and thus thereby
removed. During this process which ordinarily takes about sixteen
minutes the heat of the metal rises rapidly to about 5000° Fahrenheit.
As soon as the carbon is all consumed the blast of air is stopped, as
otherwise a rapid oxydation of the metal would ensue.
This process
which is successfully employed in the manufacture of steel from crude
iron does not effect the removal of the sulphur and phosphorus, which
are eliminated if at all by a subsequent and distinct operation.

page_text: By the present Invention, which I term "the carbonic acid pneumatic
process," it is proposed to effect the removal of the sulphur and phos-
phorus from the iron while it is yet in the converter and before it has
been allowed to cool by means of carbonic acid gas either applied as
a separate blast immediately on the cessation of the atmospheric blast
in the pneumatic process or by combining carbonic acid gas with the
atmospheric air in that operation.
But in order that this Invention may be readily understood I will
proceed to describe the manner in which it is carried into operation
when applied as a part of the atmospheric pneumatic (or so called
Bessemer) process.
The accompanying Drawing represents the apparatus which it is
proposed to employ, which is similar in many of its details to that used
in the pneumatic process.
In the Drawing A is the converter, an egg-shaped iron vessel exactly
like that used in the atmospheric pneumatic process; it is supported on
pillar blocks a by trunnions placed above the centre of gravity of the
vessel so as to incline it to preserve a vertical position and yet not
prevent it from being tilted over in order to pour out the metal at the
close of the operation. One trunnion c is hollow and communicates
externally with the blast pipe d and internally with the interior of the.
converter by means of a passage b which conducts the blast to tuyere
holes in the bottom of the converter A. B is the blast cylinder of
ordinary construction by which a blast of air, or of carbonic acid gas,
or both as the case may be, is forced through the blast pipe d into the
converter A. The inlet pipe e admits atmospheric air into the blast.
cylinder B through the valve chest f, and the inlet pipe 9 connected-
with the gasholder D admits the carbonic acid gas. The cock or valve i
serves to regulate the supply of air or gas to the blast cylinder, and also
to shut off either or both, so that by turning it properly either gas or air.
alone or a mixture of the two may be admitted into the blast cylinder
and forced into the converter. The carbonic acid gas employed in this
process may be manufactured by the action of muriatic acid upon lime-
stone in a suitable apparatus when it is desired to use the gas pure;
but
where it is employed in combination with the nitrogen of the air it may
be conveniently procured by means of a generating oven E which con-
sists of a close arched chamber furnished with a grating forming a bed
for coke or charcoal, which being ignited a stream of atmospheric air is

page_text: forced by a fan h into the closed space under the grating or fire bed,
and the air passing through the ignited carbon combines with it and
is converted into carbonic acid mingled with nitrogen, which thence
passes through the pipe k into the gas holder D which is of ordinary
construction. The inlet pipe g of the blast cylinder B opens into the
gas, holder D.
The operation of this improvement is as follows:-The atmospheric
pneumatic process, as ordinarily practised, is carried on substantially as
before described, the valve i being set so as to force atmospheric air
through the melted metal in the converter. This is continued until
the carbon is nearly all removed, which will be usually in about sixteen
minutes, the time varying in practice with each charge of metal
according to its heat when poured into the converter, the quantity of
carbon which it contains, the pressure of blast, and other variable
causes. As soon as the process of decarbonization is about completed,
or very nearly so, the blast of atmospheric air is stopped, and by means
of the valve i a blast of carbonic acid gas is forced from the gas holder D
through the melted metal in the converter A; this blast is continued
for half a minute, more or less; the blast is then again changed and
atmospheric air admitted, which is continued for about fifteen seconds,
when the blast is stopped, the operation being complete. In order to
preserve the distinctness and purity of each kind of blast, both the air
and carbonic acid gas being introduced through the same pipe d and
trunnion c into the converter, the converter is tilted over on its trunnions
just before changing the blast, until the tuyere holes are no longer covered
by the melted metal, and the changed blast is allowed to pass through
the converter without entering the metal until all traces of the former
blast have disappeared, when the converter is restored to its upright
position and the process is continued.
The result which is accomplished by the improved process may be
briefly stated thus:-The blast of atmospheric air being continued
through the molten iron until nearly all trace of carbon has dis-
appeared, on the introduction of the carbonic acid gas a chemical union
is formed between the two equivalents of oxygen and the sulphur
present in the iron, forming sulphurous acid which passes off as gas,
depositing the carbon thereby set free, which may be expressed thus:
CO,+S SO,+C. A similar result takes place in respect to. phos-
phorus present as an impurity in the iron, the oxygen of the carbonic

page_text: acid combines with the phosphorus evolving acid gases of the phosphorus,
and depositing carbon, thus, 2CO,+P=PO,+2C, and carbon is deposited.
This deposit of free carbon may be left in the iron if preferred in the
manufacture of steel, or it may be burned out after the sulphur and
phosphorus are removed, by a repitition of the atmospheric blast for
a few seconds, as before stated. The oxygen of the carbonic acid gas
will also combine with the iron, forming ferrous acid, thus: CO₂+Fe=
2 Fe O+C, the formation of the protoxide of iron setting free and de-
positing the carbon. While the blast of carbonic acid gas is passing
through the molten iron the temperature of the metal will fall somewhat,
losing about one-fourth of the additional heat gained during the passage
of the atmospheric blast. This however is rather an advantage than
otherwise, as it is found that by the atmospheric pneumatic process
the iron is rendered almost too fluid by the extreme heat. If preferred
the carbonic acid gas may be heated before entering the converter.
A modification of the process described consists in allowing a small
proportion of carbonic acid gas to enter the blast cylinder together with
the air, and thus subjecting the molten crude iron to a combined blast
of atmospheric air and carbonic acid gas; by this means the impurities
are removed during the process of decarbonization. Other gases or
fluids may also be introduced, together with the carbonic acid gas, as
may be desired.
I do not wish to confine myself to the exact mode of introducing the
carbonic acid gas herein-before described, nor to the use of the apparatus
shown on the Drawing, as this may be modified. If the improvement
is applied to the purification of molten iron without the previous use of
an atmospheric blast passed through it, it will be necessary to apply
heat to the vessel containing the molten metal in order to keep it in
the necessary fluid condition; or the gas may be generated between
the blowing cylinder and the converter and forced into the converter by
means of the atmospheric blast, or by a separate blowing cylinder.
This improved process of removing impurities from iron in a molten
condition by means of a stream or blast of carbonic acid gas is also
applicable to puddling and boiling furnaces; the stream of carbonic acid
gas in this case being introduced by dipping the tnyere which conducts
the blast into the hearth of the working chamber; it is also applicable
to blast furnaces by introducing a stream of carbonic acid into the
molten metal in the hearth, while at the same time the process of

page_text: deoxydation of the ore is carried on higher up by means of the ordinary
atmospheric blast in the usual way. Carbonic acid gas may also be
used with advantage in removing sulphur and other impurities from
the sulphurets of copper, zinc, nickel, and other metals by passing it
as a blast or current through the metals when in a molten state.
Having thus described the nature of this Invention and in what
manner the same is to be performed, as communicated to me by my
foreign correspondent, what I claim is, the use of carbonic acid gas,
either alone or mixed with atmospheric air, or with other gases or
vapours when introduced into the body of molten iron or other metal
for the purpose of removing sulphur, phosphorus, and any other
impurities which will form chemical combinations with the oxygen of
the carbonic acid and deposit the carbon, substantially as herein-before
described.
In witness whereof, I, the said Charles Denton Abel, have hereunto
set my hand and seal, this Third day of July, in the year of our
Lord One thousand eight hundred and sixty-eight.