IMPROVEMENTS IN FURNACES FOR METALLURGICAL PURPOSES
Year: 1870

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 FURNACES FOR METALLURGICAL PURPOSES."-A com-
munication from abroad by Auguste Ponsard, of Paris, in the
Empire of France.
Sealed the 29th November 1870, and dated the 4th June 1870.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition,
on the 4th June 1870.
66
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 FURNACES FOR METALLURGICAL PURPOSES,"
a communication from abroad by Auguste Ponsard, of Paris, in the
Empire of France, to be as follows:-
This Invention relates to various improvements in the mode of and
apparatus for the treatment of ores and metals, consisting firstly, in
various improved reducing and smelting furnaces; secondly, in a novel

page_text: mode of heating these furnaces by means of gas; thirdly, in various
kinds of regenerators applied to these apparatus; fourthly, in the appli-
cation to puddling and reheating furnaces of the improved method of
heating by gas and regenerators.
The first improvements are principally applicable to the smelting of
ores of lead, tin, antimony, zinc, mercury, and such like metals, and
consists principally of a gas generator for reducing solid fuel to a gaseous
form; secondly, of a reverberatory furnace provided with what the
Inventor terms crucible tubes; thirdly, of a roasting hearth provided
with crucible tubes and also with a chamber for heating such tubes;
and, fourthly, in the application to puddling and reheating furnaces of
a gas heating apparatus and regenerator. The gas generator, the front
face of which is inclined, is provided with an oblique grating for the
reception of the combustible, which is fed into the apparatus in the
ordinary manner. The gas is admitted into the combustion chamber by
a pipe furnished by a regulating valve and partition which divide the
gas into streams which come in contact with currents of air passing
from the regenerator. Cold air is supplied by a fan or blower at a low
pressure to the body of the gas generator where the attendant is placed
who attends to the heating, and a portion passes through the grating to
support combustion, the remainder being conducted into the regenerator
below and passing through perforated bricks which heat it as it ascends,
and this hot air passes into the combustion chamber and mixes with the
gases from the gas generator, and the flame after passing through the
upper chamber enters the regenerator, and there leaves the greater
portion of its heat, passing through the perforated bricks before entering
the chimney.
The body of the gas generator may be opened and the apparatus
worked with free access of air. Vertical pipes are set in the body of
the furnace and serve as retorts in which the substances to be smelted
are placed, and the upper extremities of which pass through the roof of
the furnace and are open to the air, their lower extremities resting upon
the bed of the furnace.
The operation is rendered continuous by continually charging the
upright pipes or retorts with ore flux and fuel.
For more refractory ores, such as those of copper, gold, silver, and
iron, the first bed is done away with. For smelting volatile metals
the upright tubular retorts are closed at the top by a removeable stopper,

page_text: thus avoiding loss by volatilization and oxidation. One regenerator may
be made to serve two furnaces, so that when one of them is stopped
working for repairs the other may be kept at work.
The apparatus may be variously modified according to the purpose for
which it is intended to be employed without departing from the nature
of the improvements, which consist principally in the employment in
apparatus for such purposes of tubes which act as retorts or crucibles
for containing the ore to be smelted, also of a reduction chamber
especially adapted for treating ores and smelting metals, also of the
application to such apparatus of a gas generator and regenerator con-
sisting of perforated or solid bricks.
In order to prevent the passage of dust and particles of metal from the
furnace to the regenerator, a bridge or screen is provided between them
above the regenerator.
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 3rd December 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Mid-
dlesex, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fourth day of June, in the year
of our Lord One thousand eight hundred and seventy, in the thirty-
third 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, administrators,
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 FURNACES FOR METALLURGICAL PURPOSES," a communication
to me from abroad by Auguste Ponsard, of Paris, in the Empire

page_text: of France, 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 ascer-
tain 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 accom-
panying Drawings, and to the letters and figures marked thereon (that
is to say) :--
The said Invention relates, firstly, to various improved constructions
of reducing, melting, and smelting furnaces; secondly, to a novel mode
of heating these furnaces by means of gas; thirdly, to various kinds of
heat collectors or regenerators applied to this mode of heating; fourthly,
to the application to puddling and reheating furnaces of the improved
method of and regenerators for heating by gas.
The first improvements are principally applicable to the smelting
of orcs of lead, tin, antimony, zinc, mercury, and such like metals,
and consist principally of a gas generator for reducing solid fuel to a
gaseous form; secondly, of a reverberatory furnace provided with
what the Inventor terms "crucible tubes"; thirdly, of a roasting hearth
provided with crucible tubes, and also with a chamber for heating such
tubes; and fourthly, in the application to puddling and reheating
furnaces of a gas heating apparatus and regenerator.
The gas generator, the front face of which is inclined, is provided
with an oblique grating for the reception of the combustible, which is
fed into the apparatus in the ordinary manner. The gas is admitted
into the combustion chamber by a pipe furnished with a regulating
valve and partitions, which divide the gas into streams which come in
Cold air is
contact with currents of air passing from the regenerator.
supplied by a fan or blower at a low pressure to the body of the gas
generator, where the attendant is placed who attends to the heating,
and a portion passes through the grating to support combustion, the
remainder being conducted into the regenerator below and passing
This hot air
through perforated bricks, which heat it as it ascends.

page_text: passes into the combustion chamber and mixes with the gases from the
gas generator, and the flame after passing through the upper chamber
enters the regenerator and there leaves the greater portion of its heat,
passing through the perforated bricks before entering the chimney.
The body of the gas generator may be opened and the apparatus
worked with free access of air. Vertical pipes are set in the body of
the furnace and serve as retorts, in which the substances to be smelted
are placed, and the upper extremities of which pass through the roof of
the furnace and are open to the air, their lower extremities resting upon
the bed of the furnace.
The operation is rendered continuous by continually charging the
upright pipes or retorts with ore, flux, and fuel.
For more refractory ores, such as those of copper, gold, silver, and
iron, the first bed is dispensed with. For smelting volatile metals the
upright tubular retorts are closed at the top by a removeable stopper,
thus avoiding loss by volatilization and oxidation. One regenerator may
be made to serve two furnaces, so that when one of them is stopped
working for repairs the other may be kept in operation.
In order to prevent the passage of dust or particles of metal from the
furnace to the regenerator, a bridge or screen is provided between them
above the regenerator.
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 four Sheets of
Drawings, the same letters of reference indicating corresponding parts
in all the corresponding Figures.
The furnace represented on Sheet 1 of the Drawings is mainly.
applicable to the melting of the ores of lead, tin, antimony, zinc,
mercury, and the like. Figure 1 represents a longitudinal section of the
furnace taken along the line A-B; Figure 2 is a sectional plan along.
the line C-D; Figure 3 is a transverse section along the line E, F ;.
and Figure 4 is a transverse vertical section taken along the line G, H.
The essential features comprised in this furnace are:-
1. A gas generator for reducing the solid fuel to a gaseous condition.
2. A reverberatory furnace fitted with "crucible tubes."
3. A licat regenerator.

page_text: The gas generator A, of which the front face B is inclined to an
angle of from 40° to 50°, is provided with an inclined grating O for the
reception of the fuel, which is charged into the apparatus by an ordinary
valvular feeder D. The admission of the gas into the combustion
chamber F is accomplished through the conduit E, which is provided
with a regulating valve G, and is divided at its upright portion by a
number of partitions H, which break up the stream of gas into a number
of small currents at the point where it meets a series of hot air jets J
arriving from the heat regenerator by the conduit I. The cold air is
driven by a fan or otherwise under slight pressure into the closed ash-
pit of the gas generator, under the covering plate N of which is placed
the attendant who has charge of the gas generator. A portion of the
cold air passes through the grate to support combustion whilst the
remainder passes into the heat regenerator by the conduit and valve M.
The cold air thus entering the regenerator at its lower part, which is
the coolest, rises as it passes transversely several times amongst the
heated hollow bricks L, as shewn in Figure 4, and thus gradually takes
up caloric therefrom till it arrives at the combustion chamber F at a
temperature nearly approaching that of the fumes which pass off from
the crucible chamber K. This hot air directed into the combustion
chamber by the conduit I mixes with the gas arriving from the generator,
and the flame thus produced, after having traversed the crucible
chamber K, enters the heat regenerator L where it parts with the
greater portion of its caloric whilst passing through and amongst the
bricks on its way to the chimney. The construction of this kind of heat
regenerator is exceedingly simple, the bricks composing the body of the
same being maintained at uniform or nearly uniform distances apart
by walls which exactly cover the points of junction. When it is
desired to work the furnace under the sole draught of the chimney, it
is simply requisite to uncover the ash-pit when the free air will enter
the apparatus under the draught solely of the chimney, the amount
of supply being regulated as before by the valve M. The hearth O of
the furnace has a number of holes made therein into which are fitted
the lower ends of the "crucible tubes" P for the reception of the
materials to be melted, whilst the upper ends of the said tubes pass out
through the roof of the furnace into the free air, as shewn in Figures 1
and 3. Immediately beneath the lower ends of the tubes is the lower
hearth Q of fire-clay, the sides of which are inclined so as to form
a basin or reservoir wherein the melted materials collect and arrange

page_text: themselves according to their relative densities. The fluid scoria is run
off by the orifice R and the metal is tapped off through a hole which
is kept closed during the melting process. By maintaining a constant
supply of ore, fluxes, and fuel in the several "crucible tubes," the
process may be carried on continuously. This arrangement of furnace
is specially adapted for treating ores of tin, lead, zinc, and antimony,
but for copper, gold, silver, and iron ore the first hearth is dispensed
with. When melting volatile metals the "crucible tubes" are closed
at their upper ends by tight-fitting moveable covers. This method of
fusing possesses the advantage when treating ores of lead, zinc, and
antimony of preventing all loss by volatilization, as it cannot be carried
off along with the flame and draught of the furnace, and may, if desired,
be readily passed into a condenser. Moreover, the ore being sheltered
by the crucible is protected from oxidation by contact with the flame;
whilst, if desired, a small quantity of powdered charcoal may be thrown
into the receiver in order to reduce the portions of metal which may
have become oxidised and to maintain such chamber or reservoir always
charged with a reducing gas.
Figures 5 and 6 (Sheet 1) represent two arrangements of furnaces
worked by one regenerator placed between the two, and disposed citler
horizontally, as in Figure 5, or vertically, as in Figure 6. By this
arrangement when one furnace is stopped for repairs the whole of the
heat accumulated in the regenerator is utilized by the second furnace.
The furnace represented at Figures 1, 2, 3, and 4, on Sheet 2 of the
Drawings is intended for the continuous melting in crucible tubes of
ores generally, but is more particularly suitable for ores of iron, copper,
lead, tin, gold, and silver, the ashes of gold, cast iron, wrought iron,
steel, and other metals. It consists like the one previously described of
a gas generator, a reverberatory furnace, and a heat regenerator or
collector. Figure 1 represents a longitudinal section of the furnace on
I, J; Figure 2 is a horizontal section on K, L; Figure 3 is a transverse
section on M, N; Figure 4 is a similar section on O, P; Figure 5 is
a vertical section on Q, R; and Figure 6 is a horizontal section on S, T.
The gas arrives at the furnace by the flue S and the air by the passage T.
The flame expands in the chamber of the furnace, across which pass the
crucible tubes U for the treatment of the ores or for the manufacture of
steel. The hearth V as well as the roof ✗ of the furnace are depressed
or sunk towards their centre, and carry a series of crucibles U situate

page_text: on each side on the inclined planes which form the basin wherein the
melted metals collect.
In order to apply this furnace to the puddling of iron or to the re-
heating of wrought iron the hearth should be constructed of the form
employed in furnaces for carrying out those processes. The current of
ignited gas and air issues from the chamber of the furnace to enter the
heat collector or regenerator by a series of vertical conduits, heating in
its passage a chamber W intended for the reduction and preliminary
roasting of the ore. In the roof of this chamber W there are supported
a series of tubes Y for the reception or the ore, which before being
melted requires to be reduced, and which is there thrown in after having
been broken and mixed with charcoal and the necessary fluxes. The cal-
cined products are withdrawn through the door Z, to be thence conveyed
to the crucible tubes U wherein the melting or fusion is effected.
Iron intended for the manufacture of steel may also undergo the
preliminary processes of cementation and heating in the same chamber W.
The current of ignited gas on leaving the furnace enters the reduction
chamber W by several openings and horizontal registers for controlling
the admission. The reduction takes place partly within the tubes, and
as fast as the reduced metal is withdrawn through the lower door that
which has accumulated in the tubes descends to the lower part of the
chamber. The reducing chamber may be replaced by a small chamber
serving for the preliminary heating of substances to be treated in the
furnace.
The heated products of combustion arising from the combustion of
the gas and air traverse the entire length of the horizontal spaces formed
by the series of hollow bricks a disposed in the chamber of the heat
collector, and from there they pass direct into the chimney b, at the
entrance to which there is fitted a damper c for controlling the draught.
The cold air from the ash-pit of the gas generator is admitted into the
heat collector by the valve d, it traverses the heated hollow bricks a, the
baffle walls e, e, compelling the air to pass alternately from one side to
the other of the apparatus, and to finally enter by the flue T into the
combustion chamber of the furnace.
Figures 5 and 6 (Sheet 2) represent a special construction of the roof
and hearth fof a melting furnace, also an arrangement of heat collector
composed of tubes of fire-clay. The roof of the furnace is composed of
curved or arched parts h of brickwork having the open spaces or intervals

page_text: filled in with pieces of fire-clay placed close together, and perforated
for the reception of the crucible tubes. This simple arrangement may
also be employed for keeping in position the fire-clay tubes j of the heat
regenerator. These tubes are maintained in position at their upper ends
by a series of perforated pieces of fire-clay k filling the spaces between
the arches of the roof of the regenerator. At their lower ends they
rest in recesses or shoulders formed inside perforations made in the
blocks m which fill the spaces between the arches u forming the lower
floor of the apparatus. The heated gases from the furnace enter by the
flue o into the regenerator and surround the tubes; which they heat
before reaching the chimney p. The cold air on the contrary enters the
apparatus by the flue g and passes through the interior of the groups of
tubes j by traversing successively the spaces r and 8 formed at the upper
and lower part of the apparatus, and finally enters the chimney of the
furnace through the flue g.
The furnace represented by Figures 1, 2, 3, and 4 (Sheet 3), is specially
adapted for the reduction and roasting of ores requiring to be thus treated
before being melted. Figure 1 is a longitudinal section on the line
U, V; Figure 2 is a horizontal section on the line X, Y; Figure 3 is a
transverse vertical section on Z, W; and Figure 4 is a similar section
on the line A, B. This furnace, like those herein-before described, is
heated by means of a gas generator of my improved system, and also by
means of a heat collector, it is in addition provided with a chamber for
drying and heating the fire-clay tubes. The ores are in this system
charged from the upper part of the furnace into a series of "crucible
tubes" t wherein they are acted upon by the heated gases passing along
the flue ; from the gas generator the roasted substances fall into a
lower chamber, whence they pass through a series of hoppers v into
wagons which convey them to the melting furnaces herein-before
described and illustrated on Sheets 1 and 2.
The heat collector which is combined with this furnace is composed
simply of solid bricks y set openly and so as to break joint and separated
by a series of parallel walls z, between which circulate the flames from
the roasting furnace which enter the chimney by the flue W. The
cold air arriving by the flue a traverses the free spaces between
the bricks and enters the combustion chamber of the furnace by the
conduit B.

page_text: The chamber C which serves for the drying and heating of the
crucible tubes is disposed as shown in Figure 1 above the regenerator so
that it shall only receive a moderate heat sufficient for the purpose
required.
The tubes to be baked or kept hot are placed in a species of muffle of
fire-clay, as shewn in Figure 1, for the purpose of protecting them from
immediate contact with the flame.
The system of melting furnace shewn at Figures 5 and 6 is very
similar to the furnace shown on Sheets 1 and 2; it is like them
provided with a gas generator working under pressure and with a
regenerator. The hearth a is formed upon a horizontal metal plate and
is sunk towards the middle to form a receptacle for the melted products
which fall from the crucible tubes, b which are held in the roof by the
perforated slabs of fire-clay, as before described, in reference to Figures
5 and 6 on Sheet 2. This furnace is further provided with a chamber c
for the heating of the tubes.
The heat collector is composed of a series of solid bricks d placed
horizontally in the same manner as they are placed vertically in the
heat collector shown in Figures 1, 2, and 4 (Sheet 3), that is to say, the
products of combustion traverse the partitions which divide or separate
them before they reach the chimney; whilst the cold air before entering
the combustion chamber encounters the heated bricks and takes up a
portion of the caloric which they contain.
Figures 1, 2, 3, 4, (Sheet 4), represent a steel furnace constructed
according to this Invention heated by gas and provided with a heat
collector. Figure 1 represents a longitudinal vertical section along the
line A, B; Figure 2 is a plan and horizontal section along the line
C, D; Figure 3 is a transverse vertical section along the line E, F;
and Figure 4 is a similar section along the line G, H.
In this system of furnace the chamber a in front of the gas generator
is constructed of metal plates and is closed air-tight by means of two
doors b, b, having a sufficient space between them to enable the
attendant to enter without permitting of any escape of air or reduction of
pressure inside the said chamber, which pressure is maintained by means
of a fan or other suitable blower, or by a steam injector x, the workman
first entering the outer door and closing it behind him before he opens
the inner door. The combustible gases are burnt in the combustion

page_text: chamber c by the hot air from the heat collector d, and impart a high
temperature to the working chamber e, and afterwards to a chamber f,
wherein are placed the blocks of wrought and cast iron intended to be
made into steel. The products of combustion finally enter the vertical
heat collector d, whence they pass through the chimney into the
atmosphere. The cold air from the chamber a enters the heat collector
by the pipe g, traverses the heated hollow bricks of the collector, and
passes by the flue h into the combustion chamber c.
Figures 5, 6, and 7 represent the application of the improved system
of heating by gas and the use of a heat collector to an ordinary puddling
furnace.
The heat collector represented in the Drawings consists of a series of
vertical parallel walls or partitions i, between which circulate in opposite
directions the heated gases from the furnace and the cold air intended to
burn the gas issuing from the gas generator. The spaces between the
partition walls are traversed by a series of hollow bricks k disposed so
as to break joint and thereby form baffle surfaces for the circulation on
the one part of the heated gases and on the other of the cold air. This
arrangement which is exceedingly simple and economical in construction,
admits of a very powerful regenerator being constructed in a small space
whilst presenting at the same time a considerable extent of heating
surface. I may here further point out the application to a puddling
furnace of baffle surfaces or walls intended for arresting the passage of
metallic dust or particles along with the draught, which without this
arrangement would soon obstruct the passages of the heat collector.
It is also to be understood that the same arrangements may be applied
to ordinary reheating furnaces and other furnaces of a like character.
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 construction and use of a melting furnace provided with
crucibles in the form of tubes for the treatment of ores of lead, tin,
antimony, zinc, mercury, and other like ores, substantially as herein-
before described.

page_text: Second. The construction and use of a melting furnace provided with
crucibles in the form of tubes, and with a reduction chamber for the
treatment of ores of iron, copper, lead, tin, gold, and silver, also gold
ash, and for the melting of cast and wrought iron, steel, and other
metals, substantially as herein-before described.
Third. The construction and use of a reducing and roasting furnace
provided with crucibles in the form of tubes and with a heating chamber
for heating the said crucibles, substantially as herein-before described.
Fourth. The construction and use of a melting furnace for ores and
metals provided with crucibles in the form of tubes, and having a 1
reduction chamber for heating the said crucibles, as herein-before
described.
Fifth. The construction and use of a steel melting furnace provided
with a gas generator and heat collector, arranged and combined together
substantially as herein-before described.
Sixth. The peculiar constructions and arrangements of heat collectors,
as and for the purposes herein-before described and illustrated by the
Drawings.
E
1
Seventh. The application and use to and in the herein-before described
improved and other metallurgical furnaces of the system of heating by 2
gas by the aid of a gas generator provided with a working chamber and
disposed so as to be capable of being worked by the draught alone of a
chimney or by any suitable air forcing apparatus, substantially in the
manner hercin-before described.
Eighth. The application and use to and in the herein-before described 2
improved and other metallurgical furnaces of the various heat collectors
composed entirely of hollow or solid bricks, substantially as and for the
purposes herein-before described.
Ninth. The application and use to and in the various forms of
furnaces herein referred to of roasting chambers and chambers for 3
the heating of the tubular crucibles, substantially as herein-before
described.
Tenth. The application and use to and in puddling and reheating
furnaces of walls or obstructions so disposed as to arrest any fragments

page_text: of material carried along by the draught before reaching the chimney,
substantially as herein-before described.
In witness whereof, I, the said John Henry Johnson, have to this
my Specification set my hand and seal, this Second day of
December One thousand eight hundred and seventy.
J. HENRY JOHNSON. (L.S.)