Improvements in and Apparatus for Obtaining Metals by Electrolysis.
Year: 1892

page_text: Date of Application, 5th Sept., 1892
Complete Specification Left, 29th May, 1893-Accepted, 1st July, 1893
PROVISIONAL SPECIFICATION.
Improvements in and Apparatus for Obtaining Metals by
Electrolysis.
I, HANS HEINRICH FREI, of Hirzel, Bezirk, Horgen, Kanton Zurich, Switzerland,
Electrical Engineer do hereby declare the nature of this invention to be as
follows:-
Heretofore it has been usual to heat the vessels employed in the manufacture or
production of metals by electrolysis by heat produced by the combustion of solid
or gaseous fuel outside the vessel.
By this method of external firing, the vessel is exposed to the destructive action
of flame and hot gases with the result that it is quickly destroyed. The interior
of the vessel is also subject to the action of the electrolyte therein which is usually
a destructive one. Now this invention has for object to obviate these dis-
advantages. For this purpose the vessel and its contents are heated by bodies
hereafter called heaters, that are in the form of tubes, inuffles, retorts or the like
that are located in the lower portion of the vessel and are heated internally by the
combustion of solid, gascous or liquid fuel, heat being transmitted from these
heaters to the electrolyte by a molten metallic bath.
In the accompanying drawings,
Fig. 1 is a vertical section on the line c d of Fig. 2, and
Fig. 2 is a vertical section on the line ab Fig. 1 showing by way of example
electrolytical decomposing apparatus heated according to this invention.
A-B is the electrolytical decomposing vessel to contain the clectrolyte or fused
material C from which metal is to be separated by electrolysis. This vessel may
advantageously be made of iron and when in use be connected to the negative pole
of an electric generator so that it will also serve as the negative electrode, as well
understood. E represents metal for example aluminium, having a lower melting
point than the metal of the vessel A B, and which has been separated from the
electrolyte by electrolysis, or which may be placed in the vessel at the commence-
ment of the operation. FF are the heaters by which the vessel and its contents
are heated internally according to this invention. These heaters in the example shown,
consist each of a metal tube that extends through the lower part of the vessel A. B
and the metal therein and also through stuffing boxes G and is provided with
perforated conduits H and I of refractory material through which combustible gas
and air respectively can be supplied from suitably arranged gas generators and air-
heaters. These gases upon being burnt, heat the tubes F to a high temperature
and the heat is transmitted either directly to the electrolyte C, or through the
metal E when this is present. K K are positive electrodes.
By supplying heat in the manner described, the vessel A. B does not come in
contact with the flame and hot gases due to the combustion of the gaseous or other.
fuel and consequently it cannot become burnt through and allow the contents
thereof to flow away as frequently happens when the electrolytical decomposing
vessel is heated externally. Furthermore the heating bodies F when surrounded
by melten metal such as E are protected against any chemical action of the
electrolyte that might otherwise result. Thus it will be seen that fluxes which
attack material such as that of which the heating bodies are made, can in the
apparatus constructed as described, be entirely separated from the heating bodies
so that all liability of the latter being injuriously attacked is obviated. This
separation which is effected by reason of the molten metal sinking to the bottom of
the vessel, is obviously not possible when the walls of the vessel are heated
externally, because the molten metal runs off these walls. In the latter case the

page_text: vessel could of course be protected by a lining of material not liable to be
attacked by the fluxes, but such a lining must be of solid material that will not melt
at the temperature of the bath, and can therefore in most cases not be a metal, since
this would be liable to melt and sink, to the bottom of the vessel, and the use of a
solid non-metallic protective lining would be accompanied by a great loss in the
transfer of heat to the bath. Furthermore the molten metal E in addition to
separating the heating body from the electrolyte, has the great advantage of being
a good conductor of heat. This use of the molten metal as a transmitter of heat is
also so much the more important, as there are some electrolytes, as for instance
cryolite, which at a red heat attack all other materials both metallic and non-
metallic. When however as in the above construction of apparatus the separating
metal itself constitutes the transmitter of heat, the electrolytical action of the
current opposes the chemical action of the electrolyte because the said metal
then forms the negative electrode upon which fresh metal is continually being
deposited.
Dated this 5th day of September 189
H. H. FREI,
By L. W., per F. B.
COMPLETE SPECIFICATION.
Improvements in and Apparatus for Obtaining Metals by
Electrolysis.
I, HANS HEINRICH FREI, of Hirzel, Bezirk, Horgen, Kanton Zurich, Switzer-
land, Electrical Engineer 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 :-
Heretofore it has been usual to heat the vessels employed in the manufacture or
production of metals by electrolysis, by heat produced by the combustion of solid
or gaseous fuel outside the vessel.
By this method of external firing, the vessel is exposed to the destructive action
of flame and hot gases with the result that it is quickly destroyed. The interior of
the vessel is also subject to the action of the electrolyte therein which is usually a
destructive one. Now this invention has for object to obviate these disadvantages.
For this purpose the vessel and its contents are heated by bodies hereafter called
heaters, that are in the form of tubes, muffles, retorts or the like that are located in
the lower portion of the vessel and are heated internally by the combustion of
solid, gaseous or liquid fuel, heat being transmitted from these heaters to the
electrolyte by molten metal.
In the drawings filed with my Provisional Specification,
Fig. 1 is a vertical section on the line c d of Fig. 2, and
Fig. 2 is a vertical section on the line ab Fig. 1 showing by way of example
electrolytical decomposing apparatus heated according to this invention.
A-B is the electrolytical decomposing vessel to contain the electrolyte or fused
material C from which metal is to be separated by electrolysis. This vessel may
advantageously be made of iron and when in use be connected to the negative pole
of an electric generator so that it will also serve as the negative electrode, as well
understood. E represents metal for example aluminium, having a lower melting
point than the metal of the vessel A. B, and which has been separated from the
electrolyte by electrolysis, or which may be placed in the vessel at the com-
mencement of the operation. F F are the heaters by which the vessel and its
contents are heated internally according to this invention. These heaters in the
example shown, consist each of a metal tube that extends through the lower part
of the vessel A B and the metal therein, and also through stuffing boxes G, and is
provided with perforated conduits H and I of refractory material through which
combustible gas and air respectively can be supplied from suitably arranged gas

page_text: generators and air-heaters. These gases upon being burnt, heat the tubes F to a
high temperature and the heat is transmitted either directly to the electrolyte C
as at starting, or through the metal E when this has been added or has accumulated
and the level of which should then he maintained sufficiently high to cover the
heaters during the electrolytical process. K K are positive electrodes.
By supplying heat in the manner described, the vessel A B does not come in
contact with the flame and hot gases due to the combustion of the gaseous or other
fuel, and consequently it cannot become burnt through and allow the contents
thereof to flow away as frequently happens when the electrolytical decomposing
vessel is heated externally. Furthermore the heating bodies F when surrounded
by molten metal such as E are protected against any chemical action of the
electrolyte that might otherwise result. Thus it will be seen that fluxes which
attack material such as that of which the heating bodies are made, can in apparatus
constructed as described, be entirely separated from the heating bodies so that all
liability of the latter being injuriously attacked is obviated. This separation,
which is effected by reason, of the molten metal sinking to the bottom of
the vessel, is obviously not possible when the walls of the vessel are heated
externally, because the molten metal runs off these walls to the bottom of the
vessel. In the latter case the vessel could of course be protected by a lining
of material not liable to be attacked by the fluxes but such a lining must be of
solid material that will not melt at the temperature of the bath, and in most cases-
cannot be a metal, since this would be liable to melt and sink to the bottom of the
vessel, and the use of a solid non-metallic protective lining would be accompanied
by a great loss in the transfer of heat to the bath. Furthermore the molten
metal E in addition to separating the heating body from the electrolyte, has the
great advantage of being a good conductor of heat. This use of the molten metal
as a transmitter of heat is also so much the more important, as there are some
electrolytes, as for instance cryolite, which at a red heat attack all other materials
both metallic and non-metallic. When however as in the above construction of
apparatus the separating metal itself constitutes the transmitter of heat, the
electrolytical action of the current opposes the chemical action of the electrolyte
because the said metal then forms the negative electrode upon which fresh metal is
continually being deposited.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. Apparatus for the production of metals by electrolysis in which the electrolyte
is melted by heaters such as described located within the electrolytical decomposing
vessel and heated internally by the combustion of gaseous or other fuel as set
forth.
2. In the production of metals by electrolysis within a vessel constructed with
heaters such as referred to in the preceding claim, the employment of the separated
molten metal as a transmitter of the heat due to the combustion of gaseous or other
fuel within the heaters to the electrolyte above the same the molten metal being for
this purpose maintained at a sufficiently high level to cover the said heaters as set
forth.
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1
20010
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.