IMPROVEMENTS IN THE MANUFACTURE OF STEEL AND IN THE APParatus EMPLOYED THEREIN
Year: 1874

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn
Fields, in the County of Middlesex, Gentleman, for the Invention
of "IMPROVEMENTS IN THE MANUFACTURE OF STEEL AND IN THE APParatus
EMPLOYED THEREIN."-A communication from abroad by Charles
Pernot of Paris. in the Republic of France, Manager.
Sealed the 2nd June 1874, and dated the 16th April 1874.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition, on
the 16th April 1874.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County
of Middlesex, Gentleman, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE MANUFACTURE OF STEEL AND IN THE
APPARATUS EMPLOYED THEREIN, a communication to me from abroad by
Charles Pernot, of Paris, in the Republic of France, Manager, to be as
follows:-
"
This Invention relates partly to the system of mechanical puddling
for which Letters Patent were granted to me August 27th, 1873, No.

page_text: 2819, and December 31st, 1873, No. 4291, and consists chiefly in the
application of the improved furnace with a removeable inclined rotatory
hearth to the manufacture of cast steel, but it also embraces improve-
ments in the manufacture of steel which may be carried out by the use
of either the said improved furnace or any other description of rotatory
puddling furnace.
By means of this Invention the following results are obtained,
namely:-
First. The production of cast steel from cast iron alone.
In all the experiments hitherto made with a view to obtain steel from
cast iron alone the cast iron has been decarbonized or reduced to the
required proportion of carbon in a furnace having a stationary hearth
under the action of oxidizing gases or scorice, but the steel produced is
deficient in homogeneity, and the process is long and burdensome. By
the use however of the inclined rotatory hearth the metal is conducted
up the hearth to its summit by the act of rotation, and descends again
in the form of undulating streamlets, so that the gases and scorice are
rendered more effective, the oxidation is accelerated, and the period
required for the production of the necessary reactions is considerably
reduced.
Secondly. The production of cast steel from a mixture of cast iron
and steel or cast iron and wrought iron by introducing the whole of the
substances into the furnace simultaneously.
According to the ordinary method the operation is performed by
successive charges, whereby the time required is increased in the ratio of
the period necessary for the fusion of the whole of the charges. By the
use however of this Invention the entire charge may be inserted at once,
as the cast iron being more fusible than the other substances serves when
melted as a primary bath, and the other substances not yet melted are
caused by the rotation of the inclined hearth to pass into the bath of
cast iron and impart thereto a portion of the oxygen they contain, and
relieve the cast iron of a portion of its carbon, and after a relatively
short period the equilibrium is established between the oxygen and the
carbon, and the whole bath is melted and homogeneous. The malleability
and hardness of the metal may then be tested, and should it not be of
the requisite quality a sufficient quantity of wrought iron, steel, or cast
iron may be added according to circumstances.

page_text: Thirdly. The conversion of cast iron into steel direct by the addition
after the decarbonization of spiegel eisen or any other recarburizing
metal in any description of rotatory puddling furnace. This operation
has not hitherto been performed in any furnace of this class, all previous
efforts having been directed to the conversion of cast iron into wrought
iron exclusively and not into steel.
Fourth. A metal of a homogeneous quality is obtained by the rotation
of the movable. inclined hearth, as the heat is uniform and an intimate
mixture is constantly effected, the position of every portion of the metal
being successively changed and exposed to the heat and immersed again
in the bath, thereby preventing burning, which is a most essential
condition in the manufacture of steel.
Fifth. Repairs are facilitated, as the hearth may be moved away and
operations proceeded with without waiting for the furnace to cool,
whereby a considerable saving in time is effected.
Sixth. A perfectly tight joint of the movable hearth with the
stationary portion of the furnace is not required, but on the contrary a
considerable degree of play may be allowed. The gases and air arrive
in the furnace at a temperature considerably below that which is attained
when they are mixed and burnt; by combining together their volume is
increased, and an internal pressure is produced which prevents the
admission of the external atmosphere through the joint.
'
In carrying out this Invention it is proposed to form in the lower part
of the inclined rotatory hearth a tapping hole through which the molten
metal is discharged. A carriage mounted on wheels is employed, which
carriage is provided with a suitable gutter, along which the metal is
conducted into the casting ladle and thence into the moulds. This
carriage also serves for the charging of the furnace, and carries a
platform for the workmen employed in performing that operation.
Motion is transmitted to the rotatory hearth from any convenient prime
mover by means of bevel gearing through the intervention of a shaft
arranged at an angle to the vertical plane or otherwise.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Henry Johnson in the Great Seal Patent
Office on the 9th October 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixteenth day of April, in the year
of our Lord One thousand cight hundred and seventy-four, in the
37th year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Henry Johnson, Her special
license that I, the said John Henry Johnson, my executors, admini-
strators, and assigns, or such others as I, the said John Henry
Johnson, my executors, administrators, or 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 "IM-
PROVEMENTS IN THE MANUFACTURE OF STEEL AND IN THE APPARATUS EMPLOYED
THEREIN," a communication to me from abroad by Charles Pernot,
of Paris, in the Republic of France, Manager, upon the condition
(amongst others) that I, the said John Henry Johnson, my executors
or administrators, by an instrument in writing under my hand and
seal, 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 John Henry Johnson, 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, reference being had to the accompanying
Drawings and to the letters and figures marked thereon, that is to
say: -
The said Invention relates more particularly to the system of
mechanical puddling furnace having a removable inclined rotatory

page_text: hearth, for which Letters Patent were granted to me on behalf of the
said Charles Pernot, August Twenty-seventh, One thousand eight
hundred and seventy-three (No. 2819), and December Thirty-first, One
thousand eight hundred and seventy-three (No. 4291), but it also
embraces improvements which may be carried out by the use either of
the said improved furnace or any other description of rotatory puddling
furnace.
In the Specification of the last-mentioned Letters Patent the possi-
bility is stated of producing cast steel in the improved furnace. Now
the present Invention consists in the application of the said improved
furnace to the manufacture of cast steel, whereby the following results
are obtained, videlicet :-
First. The production of cast steel from cast iron alone.
Second. The production of cast steel from a mixture of cast iron and
steel or of cast iron and wrought iron by introducing the whole of the
materials simultaneously.
Third. The conversion of cast iron into steel directly by the addition
after the decarbonisation of such cast iron of spiegel eisen or its equiva-
lent, as herein-after mentioned.
Fourth. The constant production of a homogenous mixture by the
rotation of the inclined hearth.
Fifth. Repairs may be effected more expeditiously than is the case
with other furnaces employed in the production of steel, such for
example as those known as the Martin-Siemens' furnaces.
Sixth. The furnace may be heated without the necessity for a perfect
joint of the rotatory hearth with the fixed part of the furnace, and it is
capable of operating even with a joint having a considerable amount of
play.
And in order that the said Invention may be fully understood I
shall now proceed more particularly to describe the same, and for that
purpose shall refer to the several Figures on the annexed Sheet of
Drawings, the same letters of reference indicating corresponding parts
in all the Figures.
Figure 1 represents a vertical transverse section of the furnace erected
above regenerators, as shewn; Figure 2 is a vertical section (taken at
right angles to Figure 1); and Figure 3 is a horizontal section of same.

page_text: A is the rotatory hearth of the furnace mounted on the carriage B,
which may be withdrawn to the outside of the furnace, as shewn by the
blue lines in Figure 1; C is the non-hermetical joint of the rotatorý
hearth with the fixed portion of the furnace; D is a tapping hole;
beneath which is brought the conducting channel or gutter D¹, which is
supported on a carriage E. This carriage serves for the charging of the
furnace, and it is provided with a platform E' for the workmen employed
in performing that and other necessary operations.
Underneath the
conducting channel or gutter D' there is disposed the casting ladle F,
which is itself situate above the mould G. The apparatus for trans-
mitting the rotatory motion to the hearth is shewn at H, Figure 3.
First. Production of Steel from Cast Iron alone.-In all the experi-
ments hitherto made for the production of steel from cast iron alone,
that is to say, for the decarbonisation in a furnace having a stationary
hearth of the cast iron so as to reduce the carbon to the proportion
necessary for steel of every known description, the cast iron has been
melted on a stationary hearth, as for example in the furnaces constructed
on the system known as Martin and Siemens', and after the lapse of a long
period under the action of oxidizing gases or of cinder or scorice steel is
produced, but such steel is found to be deficient in homogeneity, and the
process is morcover slow and burdensome. By the means employed
however in accordance with this Invention, videlicet, the inclined
rotatory hearth, the molten metal is conducted up the inclined hearth
by the act of rotation, and on arriving at the summit descends again in
the form of undulating streamlets. The action of the gases and of the
cinder or scorice is thus rendered much more effective, and the oxidation
is accelerated so that the reactions necessary for obtaining steel are
produced in one third of the time required by the ordinary system. The
process therefore becomes exceedingly practicable and economical, and
is rendered capable of being commercially applied.
Second. Production of Cast Steel from a Mixture of Cast Iron and
Steel or of Cast Iron and Wrought Iron by inserting the Entire Charge
into the Furnace at One Time.-The whole of the charge may be inserted
at one time since as the cast iron is more fusible than the remainder of
the charge when it is melted it serves as the primary bath, and the other
materials not yet melted are caused by the rotatory motion of the
inclined hearth to pass into the bath of cast iron and impart thereto a
portion of the oxygen which they contain, and at the same time relievo

page_text: the cast iron of a portion of its carbon. After the lapse then of a
relatively short period an equilibrium is established between the oxygen
and the carbon, and the whole mass becomes melted and homogenous,
each portion having passed into the bath. By testing now the metal
contained in the furnace the operator may ascertain whether it possesses
the desired quality of malleability and hardness, and if otherwise a
certain quantity of wrought iron, steel, or cast iron is to be added,
according to circumstances. On the contrary, in furnaces constructed
on the Martin-Siemens system, for example, the process is carried out
by successive charges, which lengthens the operation in the ratio of the
period necessary for the fusion of the whole of the separate charges.
More than double the quantity of steel may therefore be manufactured
in the improved furnace having a movable hearth than in the existing
Martin-Siemens. furnace.
Third. The Conversion of Cast Iron into Steel directly by the addition
after the Decarbonisation of such Cast Iron of Spiegel Eisen or any other
Recarburizing Metal either in the Improved Furnace or in any other
Description of Rotatory Puddling Furnace.-This operation has not yet
been performed in any furnace of this class, the cast iron having been
converted into wrought iron exclusively and not into steel.
Fourth. A Homogenous Metal is Produced by the Rotation of the
Movable Inclined Hearth.-It will be readily observed on reference to
the Drawing that a uniform heat and an intimate mixture are necessarily
obtained as the position of every portion of the metal is successively
changed so as to be exposed to the heat and thon reimmersed in tho bath,
whereby burning is prevented, which is a most essential condition in the
manufacture of steel.
Fifth. Repairs are Facilitated.-Assume that it is required to repair
the roof or any other part of the furnace. The carriago bearing the
hearth is drawn back and the portions to be repaired are broken down;
the furnace thus becomes completely open and the workmen are enabled
to proceed with their operations immediately, the causes of heat having
been removed. As soon as the repairs are completed the carriage is
brought back to its place and the furnace is heated; only the time
actually requisite for the repairs is thus lost, the necessity for leaving
the furnace for say from twenty-four to thirty-six hours to cool down, as
in the ordinary system, being obviated. With this improved system
repairs to any extent may be effected in less than six hours.

page_text: Sixth. A Perfectly Tight Joint is not Required.-The gases and air
enter the furnace at a temperature considerably below that which is
attained when they become mixed and are burnt; by combining together
their volume is increased, and an internal pressure is then produced
which prevents the admission of the external air through the joint.
In the improved furnace with an inclined rotatory hearth an increased
amount of work may thus be performed and a superior quality of steel is
produced, whilst repairs are facilitated and rendered less costly, which
advantages are of high commercial value.
Having now described and particularly ascertained the nature of the
said Invention, and the manner in which the same is or may be used
or carried into effect, I would observe in conclusion that what I consider
to be novel and original, and therefore claim as the Invention secured to
me by the herein-before in part recited Letters Patent is,-
First. The application and use to and in the manufacture of cast steel
of the puddling furnace having a removable inclined rotatory hearth, as
herein-before described.
Second. The conversion of cast iron into stecl directly by the addition
after the decarbonisation of such cast iron of spiegel cisen or other re-
carburizing metal in a rotatory puddling furnace, as herein-before
described.
In witness whereof, I, the said John Henry Johnson, have to
this my Specification set my hand and seal, the Ninth day of
wht handand and