Improvements in the Production of Aluminium and in Apparatus Employed for that Purpose.
Year: 1889

page_text: Date of Application 29th July, 1889
Complete Specification Left, 23rd May, 1890-Accepted, 19th July, 1890
PROVISIONAL SPECIFICATION.
Improvements in the Production of Aluminium and in Apparatus
Employed for that Purpose.
I, HENRY BESSEMER the younger of Townhill Park Westend near Southampton in
the County of Hants, Gentleman, do hereby declare the nature of this invention to he
as follows:-
My Invention consists in the reduction of the oxides, and other ores of aluminium,
to the metallic state, by the action of carbon and carbonaceous gases thereon, while
retained under a pressure greatly in excess of the surrounding atmosphere, and also,
the simultaneous vaporization and condensation of the reduced metal, in apparatus
specially adapted for carrying on the triple operation of reduction, vaporization and
condensation, of the metal.
In carrying my invention into practical operation, I construct a furnace, preferably
of the reverberatory type, in which the products of combustion enter the furnace
body at one end, and escape at the other, and in doing so pass over and are deflected
down upon the charge of material to be reduced, which lies on the hearth or bottom
of the said furnace. I prefer to use highly heated gaseous fuel for the purpose of
my invention, and from its cheapness and other qualities I prefer that description of
gaseous fuel known as water gas, although I desire it to be understood that liquid
fuel in the form of jets or spray may be employed. The atmospheric air employed to
support combustion is also to be highly heated by passing through red hot tubes, or
through highly heated bricks, in a manner well understood. The liquid or gaseous
fuel employed, and also the atmospheric air are forced into the furnace under a high
pressure and this high pressure is constantly maintained throughout the process,
whereby the excessive high temperature necessary to reduce the metal is obtained.
In order that the furnace employed for this purpose may be able to sustain this
high internal pressure, I construct it of iron or steel plates, giving it by preference
an elliptical form in cross section, the ends of the furnace being movable, and retained
in place by bolts, passing through flanges attached to the main body of the furnace
which is jacketted, leaving a space of a few inches between the jacket and the shell
of the furnace for the circulation of water, to keep the metal shell cool. The inside
of the furnace is protected throughout by a refractory lining. The lower part or
hearth may be formed either of plumbago or coke dust rendered coherent by admixture
with gas tar in which case a reducing flame will be maintained within the furnace.
The cold iron shell of the furnace by abstracting heat from the lining prevents its
rapid destruction when exposed to these high temperatures. It will be understood
that the orifice through which the flame and gaseous products of the furnace escape
(laden with the volatilised metal) is extremely small otherwise this pressure within the
furnace could not be maintained, and which pressure may be regulated and determined,
both by altering the speed of the compression pumps, and also by the enlargement or
contraction of the small escape aperture, which leads direct into an expansion
chamber, from which a number of condensing pipes lead to a distaut exit under a
slightly loaded valve; the said expansion chamber and the pipes are jacketed and
water circulates therein for the purpose of lowering the temperature of the gaseous
products, and condensing the vaporised aluminium. It will be understood that the
escape of the uncondensed portion of the vapors pass out of the condenser pipes at an
opening of a size very greatly in excess of the escape orifice from the furnace, hence
by reason of their reduced temperature and bulk, and the increased size of the outlet
into the atmosphere there will be very little gaseous pressure in the condenser. In
preparing the oxides or other ores of aluminium for this process, reduce them when
necessary to a finely divided state, and then mix them with a sufficient quantity of

page_text: solid carbonaceous matter such as anthracite coal, coke dust, or wood charcoal, and I
consolidate these mixed materials in suitable moulds by pressure, when in the form of
dry powder, or 1 mix therewith coal tar, or other suitable adhesive, and preferably
carbonaceous matter. These moulded lumps are to be fed into the furnace through a
suitable trap or hopper, or put in at an opening in the end of the furnace which is
closed by a luted stopper, and secured by an iron plate and screws.
Dated this 29th day of July 1980
CARPMAEL & Co.,
Agents.
COMPLETE SPECIFICATION.
Improvements in the Production of Aluminium and in Apparatus
Employed for that Purpose.
I, HENRY BESSEMER the younger of Townhill Park, Westend near Southampton in
the County of Hants, Gentleman, do hereby declare the nature of this invention and
in what manner the same is to be performed to be particularly described and ascertained
in and by the following statement :-
My invention consists in the reduction of the oxides and other ores of aluminium,
to the metallic state, by the action of carbon and carbonaceous gases thereon, while
retained under a pressure greatly in excess of the surrounding atmosphere, and also,
the simultaneous vaporization and condensation of the reduced metal, in apparatus
specially adapted for carrying on the triple operation of reduction, vaporization and
condensation of the metal.
Having now briefly described the nature of my said invention I will proceed to
describe the drawings hereunto annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a side elevation showing the general arrangement. Figure 2 is a
section to a larger scale and shows a portion of the condenser and of the nozzle by
which the heated products of combustion enter the condenser. Figure 3 is an
.clevation partly in section of the furnace or reducing chamber.
دو
A is a cylindrical vessel constructed of wrought iron or steel plates sufficiently
strong to withstand air under pressure of 3-4 or more atmospheres this vessel is
lined internally with fire brick so as to protect the iron plates from the action of the
fire to which it is subjected this vessel is also stacked with fire bricks internally in the
same way as in the "Siemens regenerator (as is well understood). This vessel or
heater as it may be termed is heated either by a portable furnace blown up by a fan
or other blast which is brought up to it and applied to the opening (a) the cover of
which has been previously removed for, that purpose, or a compound nozzle or jot
may in lieu thereof be inserted into (a) and a stream of gas either common coal gas
or what is known as water gas, or producer gas passed into the vessel with a stream
of atmospheric air for its combustion, an outlet or chimney (2) is used when heating
the heater which is afterwards removed and closed by a strong door or plate. The
mass of bricks stacked in A are by this means highly heated, when the whole contents
of A are brought to a good red heat the furnace or nozzle previously described is
withdrawn and the aperture (a) closed with a suitable plate or door securely fastened
with bolts or some other means so as to withstand the internal pressure to which it
will be subjected during the operation. Leading from the vessel A is a tube 6 which
connects it with the cylindrical or elliptical vessel B the tube b is lined with fire clay
or plumbago to prevent the overheating of the metal of which it is constructed, the
front portion of the tube b terminates in a compound nozzle through which the gaseous
or liquid fuel is introduced into the furnace B along with the requisite quantity of
air for combustion both being forced in under pressure. The tube is adapted to the
vessel A with an asbestos packed stuffing box; and the tube also has a flange at its
end which is brought to abut against a faced surface at the end of the vessel B. The

page_text: joint is luted and secured by the aid of trunnion bolts. This vessel B is constructed
of thick iron or steel plates in order to withstand the pressure to which during the
operation it is subjected the vessel B and its covers are constructed with a double
shell or skin forming a water jacket as shewn at d d in drawings into which space
water is made to circulate. The water for circulation in the water jacket may be
most conveniently arranged to enter by the trunnion or support on one side of the
vessel leaving it by the trunnion on the other side thus enabling the vessel to be
turned on its axis without breaking the water joints, the inside of the vessel or
furnace B is lined with a thinish coating of fire clay-ganister or other refractory
material, the water jacket before alluded to enables the thin gannister or other lining
to withstand the excessive temperature to which it is subjected during the smelting
operation, by reason of its absorbing a certain amount of heat from the outside portion
thereof and thus preventing the fusion or destruction of the lining. The vessel B is
preferably, mounted on trunnions shewn at e to facilitate the lining of same, if
ganister is used, the lining requires ramming in round a suitable mould of the exact
shape and dimensions of the interior portions of the furnace. The trunnions e are
supported on suitable frames f. g is a tubular outlet from the furnace B lined with
a fire clay or plumbago tube having only a small orifice as shewn so as to retard the
escape of the products of combustion and other matters issuing from the furnace.
This orifice is still further reduced in size by advancing the fire clay plug i fixed to
the end of the tube h. The products of combustion coming from the furnace B may
by this means be checked in their flow and thus any pressure required may be main-
tained in the furnace B which for this reason I will designate the high pressure
furnace. The third vessel in the series C is also constructed of plate iron and water
jacketed as shewn, a portion of the same near where the gases escape from the
furnace B being lined with fire brick, to protect the iron plates of the vessel where
the issuing intensely heated gases coming from the pressure furnace would otherwise
impinge this vessel I call the condenser and it is used as will be afterwards explained.
The condenser C is also furnished with an outlet to which an iron funnel k is attached
to carry off all the products from the pressure furnace B which are not condensed in
their passage through the condenser C. The funnel k if necessary may be provided
with a flap valve which allows the products of combustion to escape under a pressure
slightly in excess of that of the atmosphere and prevents the entrance of
atmospheric air.
Having now briefly described the nature of the apparatus, I will endeavour to
shew how it is to be employed in the production of aluminium. In commencing the
operation the heater A is by means of the portable furnace or compound gas jet as
previously explained brought to a bright red heat, the portable furnace, or gas nozzle
withdrawn and the aperture closed with a door or plate. The chimney & is also
removed and the opening closed with a door or plate. Whilst the heater A is being
heated, the pressure furnace B is also lighted, which may be conveniently done by
introducing through the feeding door y a small quantity of shavings and wood, or
some cotton waste steeped in petroleum, when this is lighted, gas and air under
pressure produced by a pumping engine or otherwise are forced in through the com-
pound nozzle in b. The gas immediately takes fire and being intimately mixed with
the hot air which is pumped through the heater vivid combustion ensues and the heat
is still further greatly augmented in intensity by reason of the restricted aperture
through which the products are allowed to escape which produces a considerable
pressure in the interior of the furnace. Thus the gas for combustion and also the
atmospheric air for supporting combustion are in a much more concentrated state than
in any furnace hitherto employed for the manufacture of aluminium.
The result of this concentration of the gas and air, is to bring the particles of gas to
be burnt into more intimate mixture with the air for supporting combustion, they
thus act upon one another with much greater intensity than in any ordinary furnace,
where combustion really takes place with gases, greatly under the atmospheric density
by reason of the expansion of the mixed gases contained in the furnace due to the
heat of the interior of the furnace itself. As most chemical reactions and combinations

page_text: .
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take place with greater energy when the solutions or materials are in a concentrated
form, than when much diluted, so we find it in this case and we are thus enabled to
obtain a temperature sufficient for the reduction of aluminium from its oxide or
other ores.
The pressure furnace B having been in operation for some time and thus brought
to an intense heat, is ready for charging. The charging door y is opened and the
materials to be operated upon inserted. In preparing the oxides or other ores of
aluminium for this process I reduce them when necessary to a finely divided state,
and then mix them with a sufficient quantity of solid carbonaceous matter such as
anthracite coal, coke dust or powdered wood charcoal, and I consolidate these mixed
materials in suitable moulds by pressure. Coal tar or other suitable adhesive matter
preferably carbonaceous may be added if found necessary as may also fluxes such as
carbonate of soda carbonate of potash borax or limestone may be added if found
desirable or the materials may be made into blocks by a machine similar to those now
used in the manufacture of compressed coal. A number of blocks or briquettes of the
material prepared somewhat as above are inserted in the pressure furnace and the
charging door y is closed a fire clay plug or stopper having been previously inserted.
The furnace is now urged to its maximum heat, the carbonaceous material mixed with
the ore or oxide, and the excess of carbonaceous gas in the furnace aided by the
excessive temperature of the pressure furnace-react upon the oxide or ore the carbon
combines with the oxygen of the ore and the aluminium is set free.
At the great
heat necessary for this operation aluminium cannot exist in a fluid form but assumes
a gaseous form, and passes with the products of combustion through the small
aperture g into the condenser C where the gases finding they are no longer restricted
expand and the temperature is thus greatly lowered so much so that the aluminium
vapour can no longer exist as such and the aluminium is deposited in the same way as
zinc and other metal when distilled.
I
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The production of aluminium by the reduction of its oxide or ore by the aid
of heat and carbon or carbonaceous matters whilst retained under pressure greatly
in excess of the surrounding atmosphere and the vaporization and condensation of
the metal as herein set forth.
2. Apparatus for the production of aluminium and consisting of an air heater, a
high pressure furnace and a condenser substantially as described.
Dated this 22nd day of May 1890.