IMPROVEMENTS IN THE MANUFACTURE OF MALLEABLE IRON AND STEEL, AND IN THE APPARATUS EMPLOYED IN SUCH MANUFACTURE
Year: 1866

page_text: of Chester, Engineer, and William George Valentin, of the Royal
College of Chemistry, Chemist, for the Invention of "IMPROVEMENTS IN
THE MANUFACTURE OF MALLEABLE IRON AND STEEL, AND IN THE APPARATUS
EMPLOYED IN SUCH MANUFACTURE."
Sealed the 12th March 1867, and dated the 9th October 1866.
PROVISIONAL SPECIFICATION left by the said George Henry Benson and
William George Valentin at the Office of the Commissioners of Patents,
with their Petition, on the 9th October 1866.
We, GEORGE HENRY BENSON, of Staleybridge, in the County, of Chester,
Engineer, and WILLIAM GEORGE VALENTIN, of the Royal College of Chemistry,
Chemist, do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN THE MANUFACTURE OF MALLEABLE IRON AND STEEL, AND IN THE APPARATUS
EMPLOYED IN SUCH MANUFACTURE," to be as follows:-
Our Invention relates to certain improvements which we have made in the
process of converting pig iron into steel or malleable iron. Owing to the
uncertainty involved in the present modes of melting down the pig iron and
spiegeleisen in the air furnaces, previous to their introduction into the
converting apparatus used for the purpose of manufacturing steel by the
pneumatic process, and owing, to the exclusive employment of atmospheric
[Price 8d.]

page_text: air as the agent for producing a suflicient heat by the combustion of iron
itself and the silicon and carbon, the quality of the steel manufactured by
this process has hitherto not been as sufficiently uniform as could be desired.
We propose to employ an atmospheric blast, by preference in a highly heated
condition, properly mixed with hot combustible gases such as are readily
obtained from gas generators. These gases consist chiefly of carbonic oxide,
hydrogen, and hydrocarbon gases, together with. non-combustible but highly
heated nitrogen and some carbonic acid gas, and are capable of producing by
the proper admixture with atmospheric blast a great heat; gases obtained by
the distillation of coal in close vessels or retorts may likewise be employed
wherever they can be obtained cheaply, and produce on account of their
greater richness and the absence of nitrogen gas a much higher heat than the
gases drawn from a gas generator. In order to thoroughly mix combustible
gases safely and securely with atmospheric blast we make use of concentric
or other tuyeres, which enable us to burn the gases thoroughly by mixing the
right and proper amounts of atmospheric blast therewith, and thus to obtain a
perfectly neutral flame or to burn the gases only partially by not admitting or
mixing a sufficient amount of atmospheric blast, when we obtain a reducing
or deoxidizing flame containing such powerfully reducing gases as hydrogen
and carbonic oxide, capable of acting upon oxide of iron and to a certain
extent upon sulphur and phosphorus in the mass of molten iron, or lastly
to burn the gases with excess of atmospheric blast when the flame becomes
highly oxidizing or decarbonizing, capable of acting upon the manganese,
silicon, and carbon in the pig iron. We propose to employ these three
conditions of flame in any desired order of succession, in order to convert pig
iron into steel, and to conduct the heating and converting processes in as
economical a manner as possible; for this purpose we prefer to employ a
stationary furnace without a fire-grate. The furnace is made deepest opposite
the place where the flame issues from a tuyere or system of tnyeres, and its
bottom rises gradually towards the throat of the furnace. The pig iron to be
melted down may be placed on the bank of the furnace to get heated
and melted down by the waste heat previous to its being brought more
directly under the action of the flame at the lower part of the furnace.
This heating and melting effect which the waste heat exerts upon the pig
iron on the bank may also be assisted and accelerated by allowing the
neutral flame of one or more additional tuyeres placed in the side walls of
the furnace to play upon the iron. A tuyere or series of tuyeres arranged
in such a manner as to produce a continuous and uninterrupted sheet of
fame from the side next to the deepest or anterior part of the furnace, which

page_text: flame is made to play over and to impinge upon the surface of the melted
metal. The flame we prefer to employ at this stage of the melting down
of the iron is a neutral or slightly reducing flame. i.c.. containing slight excess
of carbonic oxide, hydrogen, and other reducing gases. We thus protect the
manganese and carbon in the iron as well as the iron itself. and produce
simultaneously a moderate purification from sulphur and phosphorus. The
pig iron will melt more rapidly in a neutral or slightly reducing flame owing
to more perfect combustion of the highly heated gaseous fuel than can be
produced.in an ordinary wind furnace. Another tuyere or series of tnyeres
are placed below the first tuyere or series or row of inyeres, and are capable
of alternately admitting the necessary amounts of combustible gases and
highly heated aimospheric blast below the level of the melied metal under a
pressure sufficient to overcome the resistance and weight of column of the
molien iron.
!
The fuel we at different times employ consists, first. of blast and com-
bustible gases mixed so as to prodnce a reducing flame; or. second, combustible
gases mixed with the necessary amount of atmospheric blast in produce as
nearly as possible a neutral flame: or. third, combustible gases, together with
more or less excess of atmospheric blast over that required to completely
burn the gases so as to produce an oxidizing flame. When the iron has
acquired a pasty semi-fluid condition at the commencement of the process we
prefer to use combustible gases as rich in hydrogen and hydrocarbons as
possible, and fo.allow these gases to issue from the lower tuyere or series of
inyeres with an insufficient admixture of atmospheric blast. When the metal
is quite liquid we prefer, with a view of removing principally silicon and
carbon from the iron, to change the action of the flame to an oxidizing or
decarbonizing one: and, lastly, we prefer to use a neutral flame, as may during
the latter stages of the converting process be judged most advantageous by
the workmen. An oxidizing flame will only he required for a sufficiently long
time to burn out or oxidize and remove the manganese, silicon, and carbon;
any oxide of iron, which may be formed by the action of the oxidizing flame
from the lower tuyere or series of inyeres will again be deoxidized as soon as
the "boiling up" or the diffusion of the graphitic carbon throughout-the
metal takes place. The carbon can either be removed entirely or nearly so,
in which case the metal becomes converted into wrought or malleable iron,
which may be worked and used for the purposes of which such metal is
generally applied, or a sufficient amount of carbon may be left in the metal
to make it into steel, hard or soft, as may be desired, which steel may be cast
into ingots or any other forms in which it may be found most useful by simply.

page_text: tapping the furnace.
If the carbon has been removed entirely from the
metal, and it be desired io produce steel, a proportionate charge of molten
pig iron, such as spiegeleisen, Weardale, or any other iron containing a
sufficient amount of carbon, and, by preference, a pig iron containing man-
ganese as well, or also an alloy of iron and manganese, may be run into the
furnace, and the flame caused to play for some time longer upon the metal to
give the carbon of the iron time to diffuse itself thoroughly through the molien
mass. We then prefer to substitute a neutral or a slightly deoxidizing flame
from both tuyeres or series or rows of tuyeres in place of the oxidizing flame
previously employed from the lower fuyere or series of tuyères. The quality
of the steel desired can thus be more easily determined, since by the proper
admixture and diffusion of a requisite and definite weight of spiegeleisen or
other good pig iron (by preference manganiferous) containing a known amount
of carbon to a definite weight of decarbonized or wrought iron, the per-
centage of carbon introduced into the steel can be readily controlled. In
order to safely burn the gases supplied to the lower tuyere or series of tnyeres
we propose to force the gases into the tuyere or layeres by means of a fan
blast or other suitable contrivance, and the atmospheric air by means of an
ordinary blast engine or fan. We prefer to equalize the pressure for both by
means of valves or other suitable machinery: and with a view of preventing
any mixture of combustibile gases and blast. in case of unequal pressure, from
ever accumulating and diffusing themselves in the gas mains we employ a
self-acting valve or valves. The amount of gas or air to be delivered through
the tuyeres may be regulated as near as possible by means of an appropriate
adjustment of the size of mains and layere pipes, and also by throttle valves,
such as are in general use for like purposes.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said George Henry Benson and William George Valentin- in the
Great Seal Patent Office on the 9th April 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, GEORGE
HENRY BENSON, of Staleybridge, in the County of Chester, Engineer, and
WILLIAM GEORGE VALENTIN, of the Royal College of Chemistry. Chemist,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Ninth day of October, in the year of our Lord One
thousand eight hundred and sixty-six, in the thirtieth year of Her reign, did,

page_text: for Herself, Her heirs and successors, give and grant unions, the said George
Henry Benson and William George Valentin, Her special licence that we.
the said George Henry Benson and William George Valentin. our executors.
administrators, and assigns, or such others as we, the said George Henry
Benson and William George Valentin, our executors. administrators, and
assigns should at any time agree with, and no others. from time to time
and at all times thereaffer 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 Inven-
tion for "IMPROVEMENTS IN THE MANUFACTURE OF MALLEABLE IRON AND STEEL,
AND IN THE APPARATUS EMPLOYED IN SUCH MANUFACTURE," upon the condition
(amongst others) that we, the said George Henry Benson and William
George Valentin, our execuiors or administrators, by an instrument in writing
under our, or their. or one of our or 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; thai we. the said George Henry Benson and William
George Valentin, do hereby declare the nature of our said Invention, and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following thereof, statement reference being had
to the Drawings hereunto annexed, and to the letters and figures marked
thereon (that is to say):-
Owing to the
Our Invention relates to certain improvements which we have made in the
process of converting pig iron into steel or malleable iron.
uncertainty involved in the present mode of melting down the pig iron as
well as spiegeleisen, no matter whether performed in air furnaces, or in cupolas
previous to the introduction of such crude irons into the converting apparatus
now in use for the purpose of manufacturing steel by the pneumatic process,
and owing to the general if not exclusive employment of atmospheric air
as the agent for producing within such converting apparatus by the com-
bustion of the silicon and carbon, and to a large extent also by the combustion
or oxidation of the iron itself, a sufficient heat to keep the metal in a liquid
condition (whereby however much waste of the raw material is incurred),
the quality of the steel manufactured by this process has not hitherto been
as uniform as could be desired.-
The object of our Invention is to convert pig iron into steel or malleable
iron, by the employment. of gaseous fuel and atmospheric air in an apparatus

page_text: so arranged that the process may be controlled and regulated and be under
perfect command throughout. To this end we employ an atmospheric-blast,
(by preference in a highly heated condition) properly mixed with hot com
hustible gases, such as are readily obtained from gas generators.
These gases
consist chiefly of carbonic oxide, hydrogen, and hydrocarbon gases. together
with non-combustible bit highly heated nitrogen and 'some carbonic acid gas.
By proper admixture with atmospheric blast these gases are capable of
producing by their combustión a great heat. Gases obtained by heating coal
or other suitable carbonaceous matter in close vessels or retorts may, however.
likewise be advantageously employed wherever they can be obtained cheaply.
on account of the greater heating effect which they are capable of producing.
The combustible gases should for the purposes of our Invention be thoroughly
mixed with atmospheric blast. This may be safely and securely done in
various ways, but a convenient mode of so doing consists in the use of con;
centric or other tnyeres such as those shown in the -accompanying Drawings.
These layeres enable us to burn the gases thoroughly and to mix them in
the right proportions with the proper amount of aimospheric blast, so as to
produce as far as possible a neutral flame. or, also (by properly modifying
the amount of atmospheric blast) to obtain (as may be desired) either a
reducing or an oxidizing flame. By not admitting or mixing a sufficient
amount of atmospheric blast with the combustible gases so as only partially
to burn the latter, we obtain a reducing or deoxidizing flame containing such
powerfully reducing gases as hydrogen and carbonic oxide, which are capable
of acting upon oxide of iron, and to a certain extent upon sulphur and
phosphorus in the mass of molten iron. By admitting a larger proportion
of atmospheric blast than is necessary to completely burn the gases, the flame
becomes highly oxidizing or decarbonizing, and capable of acting upon the
manganese, silicon, and carbon in the pig iron, and ultimately upon the iron
itself. We further promote complete intermingling of the gases and blast
prior to their passing into the furnace by discharging the gaseous mixture
from the tuyeres into a mixing chamber or chambers constructed of fire-
proof material. We propose to employ these three conditions of flame in
any desired alternate order to convert crude iron into steel, and to conduct
the heating and converting process in as economical a manner as possible;
for this purpose we prefer to employ a stationary furnace without a fire-
grate.
In Sheet I. of the accompanying Drawings, Fig. 1 is a longitudinal vertical
section of a converting furnace constructed according to our improvements;
Fig. 2 is a sectional plan view of the same; and Fig. 3 is a cross section.

page_text: The furnace is made in the form of a basin as at a, which is opposite to
the place where the flame issues from a tuyere or system of tuyeres b. b. b'. b',
and the bank of the furnace rises gradually as at c, c, towards the throat d.
The pig iron to be melted down is placed in the furnace basin a, and a portion
may also be placed on the bank or inclined part c, c, of the furnace, where it
becomes heated short of being melted down; or if desired it may be melted
down on the bank by the flame which has to pass over it to reach the throat
of the furnace previous to its being brought more directly under the action of
the flame from the tuyeres b, '; this heating and melting effect which the
waste heat exerts upon the pig iron on the bank or inclined part e may also
be assisted and accelerated by allowing the neutral flame of one or more
additional tnyeres placed in the side walls of the furnace as at . b², to play
upon the iron.
The series of tuyeres b. b, and the mixing chamber or
chambers are arranged as shown in the sectional plan view, Fig. 2. in such a
manner as to be capable of producing a continuous and as much as possible'
undivided sheet of flame from the side next to the deepest or anterior part of
the furnace. The flame is made to play over and to impinge upon the metal
in the basin . We prefer to employ at this stage of the melting down of the
iron a neutral or slightly reducing flame: by this means we protect the
carbon contained in the iron as well as the iron itself. The pig iron will melt
rapidly and less wastefully in a neutral or slightly reducing flame owing to
the more perfect combustion of the highly heated gaseous fuel than can be
effected in an ordinary wind furnace or cupola. Another series of tuyeres b, b,
are placed below the first series or row of tugeres. and are capable of admitting
the necessary amounts of combustible gases and highly heated atmospheric
blast below the level of the melted metal under a pressure suflicient to over-
come the resistance and weight of the column of the molten iron which it is
desired to operate upon. As long as the iron is not melted, but is merely in a
pasty semi-fluid condition, at the commencement of the process we prefer to
nse from the lower series of tuyeres combustible gases as rich in hydrogen
and hydrocarbons as possible with a view of acting upon sulphur or phosphorus,
and to allow these gases to issue mixed with a small proportion of atmospheric
blast. When the metal is quite liquid we prefer (with a view of removing
principally silicon and carbon from the iron) to change the action of the
flame to an oxidizing or decarbonizing one by admitting a larger proportion
of atmospheric blast. Lastly, we prefer to use such a neutral flame as may
during the latter stages of the converting process be judged most advantageous
by the workmen to keep up the heat and yet prevent the burning of the metal.
The oxidizing flame will only be required for a-sufliciently long time to burn out.

page_text: or oxidize and remove the manganese, silicon, and that portion of the carbon
which it is desired to eliminate in order to produce steel. Any oxide of iron
which may be formed by the action of the oxidizing flame from the lower series
of tuyores will again be deoxidized as soon as the boiling up" or the diffusion
of the graphitic carbon throughout the metal takes place. The carbon can
either be removed entirely, or nearly so, by the oxidizing flame, in which
case the metal becomes converted into wrought or malleable iron, which may
be worked and used for the purposes for which such metal is generally
applied, or a sufficient amount of carbon may be left in the metal to convert it
into either hard or soft steel, as may be desired. This steel may be cast into
ingots or any other forms (in which it may be found most useful) by tapping
the furnace. If preferred the carbon may be removed entirely from the
metal, and if it be desired to produce steel a proportionate charge of molten
pig iron, such as spiegeleisen, Weardale, or any other iron containing a
sufficient amount of carbon, and by preference a pig iron containing
manganese, as well or also an alloy of iron or manganese, may be added,
and the flame caused to play for some time longer in order to give the carbon
of the iron time to diffuse itself thoroughly through the molten mass. We
then substitute a neutral or a slightly deoxydizing flame from both series or
rows of tnyeres b. b'. The desired quality of the steel can thus be more
easily determined and obtained and the process more readily controlled, and
by the diffusion of a proportionate amount of spiegeleisen or other good pig
iron (by preference manganiferous) containing a known amount of carbon
throughout a known weight of decarbonized or wrought iron, the proper
per-centage of carbon to be introduced into the metal can be more readily
determined. In order to obtain combustible gases under a pressure sufficient
to force them into a conveniently deep column of molten metal we prefer that
they should be generated in a separate furnace, retort, or generating apparatus
charged with fuel, through which an atmospheric blast of sufficient pressure
together with a small amount of steam may be forced. The form of apparatus
whereby this object (vizt.. producing combustible gases under considerable
pressure) may be effected admits of variation, but the arrangement of apparatus
which we prefer for the purposes of our Invention is shewn in Sheet II. 'of the
Drawing, in which Fig. 4 is a vertical section of a close furnace or retort for
generating gas for the lower series of tuyeres. and Fig. 5 is a plan view of the
same. m, m, is a close vessel or chamber constructed of fire-brick and encased
with sheet iron in order to render it air-tight and strong enough to withstand
the internal pressure to which it will be subjected. The fuel is fed in at top
through an opening which is closed by an air-tight stopper n; the fuel is

page_text: first ignited, and then a blast of atmospheric air is forced in under considerable
pressure from a blast engine through tuyeres o. o, arranged as shewn in the
plan view, Fig. 5, so as to cause the blast to circulate as much as possible
throughout the whole mass of fuel in the retort or furnace. The depth of the
fuel in the retort or furnace should be sufficient for the carbonic acid (first
generated by the air coming in contact with the ignited fnel) to be reduced
to carbonic oxide gas. This depth of fuel will vary according in the more or
less porous nature of the fuel employed, as is well undersinod. The furnace
shewn in the Drawing is intended for common coal or coke. but if charcoal
be used a lesser depth of fuel will be required. The exit aperture for the
combustible gases generated in the chamber m is at the lower part of the
chamber at p. and to it is adapted a pipe which conducts the gases to the
lower series of tuyeres. When the ashes or cinders accumulate at the bottom
of the chamber m they may he tapped through the opening a. or they may be
blown out by allowing the binst to pass down the pipe r and out at the tuyere
or nozzle below.
Fig. 6 is a longitudinal vertical section and Fig. 7 a plan view of a
furnace or apparatus for generating combustible gases for the upper set of
tuyeres. It will be seen that the general features of this apparatus very much
resemble those of the apparatus already described and used for generating gas
for the lower set of tuyeres, the principal difference being that the apparatus
is more capacious and that two or more rows or sets of blast tuyeres o, o, and
o', ', are to be employed; in this instance also a low pressure blast such as a
fan blast will be sufficient, as the combustible gases will have to be delivered
into the converting furnace from the upper tuyeres at a gentle pressure only.
As the atmospheric air is forced at the desired pressure through the generating
apparatus, shewn at Figures 4 and 5, by means of a blast engine or other
apparatus capable of supplying a blast under sufficient pressure, it follows that
the combustible gases generated in the apparatus will be carried along. the
pipes and through the lower series of tuyeres into the mixing chamber or
mixing chambers and through the perforated bricks or perforated clay.nozzles
into the molten metal in the converting apparatus of a considerable pressure.
A small amount of steam may also beneficially be employed, as well as
atmospheric blast, and will on coming into contact with the ignited fuel be
decomposed -into hydrogen and oxygen,, the latter combining with carbon to
form carbonic oxide; owing to the absence of nitrogen gas this gaseous
mixture will be capable of producing by its combustion a considerably higher
heating effect. The amount of gas or air to be delivered through the inyeres
must be regulated as near as possible by means of an appropriate adjustment

page_text: of the size of mains and tuyere pipes, the dimensions of which are indicated on
the Drawings; this may also to some extent be effected by throttle valves,
shch as are in general use for like purposes.
We desire it to be understood, however, that although we prefer to use the
system of concentric tuyeres, as described, for mixing combustible gases and
atmospheric blast, we do not confine ourselves thereto, but we wish to state
distinctly that such mixing effect may be attained in various other ways, and
that we make no claim to the use of concentric tuyeres over other modes of
effecting the same mixing operation.
We also wish it to be understood that we do not make any claim for the
generators we employ, since many different forms of apparatus for generating
combustible gases are known to be in use, but we give the preference to the
apparatus described as most suitable for the purposes we have in view and
being most readily under control.
In constructing the apparatus in which the gases are to be generated, as
well as the means for finally burning the same, the chemical character of the
gases to be employed, as well as their temperature and the pressure al which
they are to be used must be taken into account, as is well understood by any
practical engineer. It will be seen that the nozzles of the concentric tuyeres
are firmly fixed into a fire-brick mixing chamber or chambers, and that they
are flattened at their ends in order the more effectually to spread out the
flame. and to cause the gases and blast more thoroughly to commingle before
they enter the converting furnace. The dimensions given for the several
parts have been carefully calculated and proportioned, and we have found that
when the parts are made of the dimensions and proportions indicated they
give satisfactory results; we do not bind ourselves, however, to any invariably
fixed dimensions, as the proportions of gases and blast must vary with the fuel
employed, and as it is not possible to rigidly adhere to any given proportion
without taking into account the chemical composition of the gaseous fuel, the
temperature of the gases and blast. and the amount of pressure at which either
are delivered.
The sectional plan view, Fig. 2. shews the arrangement of pipes for
supplying the atmospheric blast and combustible gases to the two series of
tuyeres b and b¹, and also the means of heating the air blast by the waste heat
from the converting furnace; these heating pipes are seen at Fig. 1 in end
elevation.
Having now described our Invention of "Improvements in the Manu-
facture of Malleable Iron and Steel, and in the Apparatus employed in such
Manufacture," and having explained the manner of carrying the same into

page_text: effect, we claim as the Invention secured to us by Letters Patent as
aforesaid.-
First. the conversion of crude or pig iron into steel or malleable iron by
the combined action of two blasts consisting of the highly heated gaseous
products of combustion. together with more or less highly heated atmospheric
air or combustible gases, as herein set forth. one of such blasts being made to
impinge or act on the surface of the crude iron and the other to enter into and
pass through the molten metal. We claim the use of these combined blasts
in the manner herein set forth in contradistinction to the employment of a
single blast.
Second, we claim the use, in the manner herein set forth. of gaseous
fuel mixed with heated atmospheric blast. whereby a greatly concentrated
henting effect is produced, and whereby we are also enabled the better to
control the process of converting iron into steel or malleable iron, and also the
purifying action of the gases and atmospheric blast on the molten mass of
crude metal.
Third, we claim the general construction and arrangement of apparatus for
operating upon crude pig iron with combustible gases and atmospheric blast,
as herein set forth..
In witness whereof, we, the said George Henry Benson and William
George Valentin. have hereunto set our hands and seals, the Twenty-
eighth day of March. in the year of our Lord One thousand eight
hundred and sixty-seven.