Year: 1895

page_text: Date of Application (in United Kingdom), 12th Sept., 1895
Complete Specification Left, 11th June, 1896-Accepted, 8th Aug., 1596
I, THOMAS LEOPOLD WILLSON of Plaza Hotel, Fifth Avenue, corner
Fifty-ninth Street, New York City in the United States of America, Electrical
Engineer, do hereby declare the nature of this invention to be as follows:-
This invention relates to the treatment of refractory materials for their
reduction by means of electrically generated heat. Heretofore electric smelting
has been performed by subjecting the material to be reduced, tegether with the
reducing agent, to the heat generated by the passage of a continuous electric
current of uniform direction through a resisting medium, either by employing an
electric are between refractory electrodes or by forcing the current through the
resistance of a body of granulated carbon.
My present invention is based upon the discovery which I have made that by
employing an alternating current instead of a continuous current, not only is the
feeding of the material into the electric furnace greatly facilitated, but the output
of material reduced in proportion to the power expended, is nearly doubled. My
invention accordingly consists in feeding the material to be reduced in a suitably
pulverized or comminuted condition, together with the reducing agent in similar
pulverulent condition, into an electric are formed by an alternating current. When
for example aluminium is to be produced by the reduction of alumina, the powdered
alumina is fed with a powdered carbonaceous material as the reducing agent into
the vicinity of the electric arc.
In practising my invention for the production of aluminium bronze for example,
I provide preferably a Siemens are furnace with a vertical carbon pencil, and I
employ an alternating current dynamo with or without the intervention of a trans-
former, one terminal of the circuit being connected to the carbon pencil and the
other terminal to the crucible or carbon hearth of the furnace. I then take
powdered alumina and powdered or crushed carbon (which may be coal dust or
coal slack) and mix them intimately together in the necessary proportions for
reduction. I also supply a suitable amount of copper to form the base metal of
the alloy, which may be initially placed in the furnace, or it may be granulated
and mixed with the alumina and carbon. The electric furnace having been set in
operation, this mixture is then fed into the furnace so as to be introduced in the
neighbourhood of the arc, whereupon it is immediately drawn into the are by the
action of the latter, whereby the furnace becomes self-stoking so long as the supply
of the material to the furnace is maintained. This effect is believed to be due to
the alternate expansion and contraction of the gases produced by the are whereby
the mass is kept in constant and rapid vibration. The intense heat generated
by the are dissociates the oxygen from the alumina, and this oxygen is taken up

page_text: by the incandescent carbon, forming carbon monoxide or dioxide which escapes
from the furnace, while the aluminium which is set free becomes alloyed with the
molten copper, and the resulting alloy or bronze is or may be tapped off from the
furnace either continuously or at suitable intervals.
While my invention is not limited to any particular proportions as to the electro-
motive force or quantity or rapidity of alternation of the electric current yet,
I would state as one practicable example of the application of my invention,
that I have successfully produced it with a current of about 1,500 amperes at
55 volts with 120 alternations per second. Under these conditions I have produced
an output nearly double that obtained by the best practice in smelting with
continuous currents.
My invention is applicable to the electric reduction of various metals from their
ores, and to other electric smelting or electro-metallurgical operations, and is not
by any means limited to the one example that I have suggested. A further
specific application of my invention is the reduction of calcium oxide with carbon
for producing calcium carbide. For this purpose I take powdered or crushed lime
and powdered or crushed carbon and mix them in the proportions of 35 per cent. by
weight of carbon to 65 per cent. of lime, and feed them into the furnace, wherein
the heat that is generated dissociates the oxygen from the calcium, and both
combine with the carbon, forming on the one hand carbon monoxide or dioxide
which escapes from the furnace, and on the other hand calcium carbide which is
tapped off at intervals. This process so far as it relates to producing calcium
carbide I do not specifically claim in my present application for patent, as it is
specifically the subject of another application which I have already filed No. 15360
of 1895.
My present invention, by reason of the greatly increased output for a given
expenditure of energy, results in a very marked economy in the conduct of
electric smelting operations, and also by reason of the self-feeding or automatic
stoking due to the alternating current, is found practically to greatly facilitate the
conduct of the electric smelting operation.
Dated this 12th day of September 1895.
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Chartered Patent Agents.
Improvements in Electric Sm
I, THOMAS LEOPOLD WILLSON, of Plaza Hotel, Fifth Avenue, corner
Fifty-ninth Street, New York City in the United States of America, Electrical
Engineer, 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 :-
This invention relates to the treatment of refractory materials for their
reduction by means of heat generated by the electric arc. Heretofore electric
smelting has been performed by subjecting the material to be reduced, together
with the reducing agent, to the heat generated by the passage of a continuous
electric current of uniform direction through a resisting medium, either by
employing an electric are between refractory electrodes or by forcing the current
through the resistance of a body of granulated carbon. In the case of electric
are smelting, the one electrode has commonly been beneath the mass under
treatment, and the other electrode has been above. Commonly the upper electrode
is in the form of a carbon pencil, and the lower one is constituted at the outset by
the carbon hearth or bottom of the crucible, and later in the process by the pool
or bath of molten reduced materjal.

page_text: My present invention is based upon the discovery which I have made that by
employing the arc generated by a suitable alternating current instead of a con-
tinuous current, not only is the feeding of the material into the electric furnace
greatly facilitated, but the output of material reduced in proportion to the power
expended, is largely increased. My invention accordingly consists in feeding the
material to be reduced in a suitably pulverized or comminuted condition, together
with the reducing agent in similar pulverulent condition, into an electric are
formed between the electrodes, the one above the material and the other beneath,
by an alternating current of appropriate volume and frequency. When for
example aluminium is to be produced by the reduction of alumina, the powdered
alumina is fed with a powdered carbonaceous material as the reducing agent into
the vicinity of the electric arc.
In practising my invention for the production of aluminium bronze for example,
I provide preferably a Siemens are furnace with a vertical carbon pencil, and
I employ an alternating current dynamo of suitable frequency with or without the
intervention of a transformer, one terminal of the circuit being connected to the
carbon pencil and the other terminal to the crucible or furnace walls or carbon
hearth of the furnace. I then take powdered alumina and powdered or crushed
carbon (which may be coal dust or coal slack or coke) and mix them intimately
together in the necessary proportions for reduction. I also supply a suitable
amount of copper to form the base metal of the alloy, which may be initially placed
in the furnace, or it may be granulated and mixed with the alumina and carbon.
The electric furnace having been set in operation, this mixture is then fed into the
furnace so as to be introduced around the carbon pencil and in the neighborhood of
the are, whereupon it is immediately set into vibration and progressively drawn
into the arc by the pulsations of the latter, whereby the furnace becomes self-
stoking so long as the supply of the material to the furnace is maintained. This
effect is believed to be due to the alternate expansion and contraction of the gases
produced by the arc whereby the mass is kept in constant and rapid vibration.
The intense heat generated by the arc dissociates the oxygen from the alumina,
and this oxygen is taken up by the incandescent carbon, forming carbon monoxide
or dioxide which escapes from the furnace, while the aluminium which is set free
becomes alloyed with the molten copper, and the resulting alloy or bronze
is or may be tapped off from the furnace either continuously or at suitable
intervals.
While my invention is not limited to any particular proportions as to the
electro-motive force or quantity or rapidity of alternation of the electric current
yet, I would state as one practicable example of the application of my invention,
that I have successfully operated with a current of about 1,500 amperes at 55 volts
with 120 alternations (60 cycles) per second. Under these conditions I have
produced an output nearly double that obtained by the best practice in smelting
with continuous currents.
My invention is applicable to the electric reduction of various metals from
their ores, and to other electric smelting or electro-metallurgical operations, and is
not by any means limited to the one example that I have suggested. A further
specific application of my invention is the reduction of calcium oxide with carbon
for producing calcium carbide. For this purpose I take powdered or crushed lime
and powdered or crushed carbon and mix them in the proportions of 35 per cent. by
weight of carbon to 65 per cent. of lime, and feed them into the furnace, wherein
the heat that is generated dissociates the oxygen from the calcium, and both
combine with the carbon, forming on the one hand carbon monoxide or dioxide
which escapes from the furnace, and on the other hand calcium carbide which
remains in the furnace and may be removed at the end of the run. This process so
far as it relates to producing calcium carbide I do not specifically claim in my
present application for patent, as it is specifically the subject of another application
which I have already filed No. 15360 of 1895.
My present invention, by reason of the greatly increased output for a given

page_text: expenditure of energy, results in a very marked economy in the conduct of electric
smelting operations, and also by reason of the self-feeding or automatic stoking due
to the alternating current, is found practically to greatly facilitate the conduct of
the electric smelting operation.
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 I do not
claim the process herein before described so far as it relates to the production of
calcium carbide, because such production is specifically the subject of another
application for Patent No. 15360 of 1895, but what I do claim subject to this
disclaiming note is :-
1. The process of electric smelting which consists in subjecting the material to
be treated in pulverulent condition to the continued action of an electric are formed
between separated electrodes, by feeding such material into the immediate
neighborhood of the arc, and maintaining the arc by an alternating current of
a frequency adapted to set the mass of material into vibration, whereby by the
pulsations of the are the material is progressively drawn within its influence.
2. The process of electric smelting which consists in subjecting the material to
be treated in pulverulent condition to the continued action of an electric are formed
between separated electrodes, consisting the one of a pool of molten material
beneath and the other of a carbon electrode above, so that the inter-polar space is
approximately horizontal, by feeding such material upon such pool, around the
carbon electrode and into the immediate neighborhood of the arc, and maintaining
the arc by an alternating current of a frequency adapted to set the mass of material
into vibration, whereby by the pulsations of the arc the material is progressively
drawn within its influence.
3. The process of recovering aluminium from its ores or compounds, which
consists in feeding the aluminous material and carbonaceous material in a pulverulent
condition into the neighborhood of an electric are formed between separated
electrodes by an alternating current of appropriate volume and frequency adapted
to set the mass of material into vibration, whereby by the pulsations of the arc the
materials are progressively drawn within its influence.
4. The process of producing an aluminium alloy, which consists in feeding
alumina and carbon in pulverulent condition into the neighborhood of an electric arc
formed by an alternating current between a molten bath of base metal and a carbon
electrode above and out of contact with said bath, the alternating current being of
appropriate volume and frequency adapted to set the mass of material into
vibration, whereby by the pulsations of the are the materials are progressively
drawn within its influence.
Dated this 11th day of Lun 1802
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Chartered Patent Agents.