Method of Smelting or Heating Iron or other Metals by Means of Electricity, and Apparatus therefor.
Year: 1892

page_text: Date of Application (in United Kingdom), 2nd Sept., 1892
Complete Specification Left, 2nd June, 1893-Accepted, 12th Aug., 1893
LIONAIS
CIBUIFICATION.
Method of Smelting or Heating Iron or other Metals by Means of
Electricity, and Apparatus therefor.
I, CARL GUSTAF PATRIK DE LAVAL, Dr. Phil. of No. 16^ Handtverkaregatan,
Stockholm, Sweden, do hereby declare the nature of this invention to be as
follows:-
The present method of smelting iron or other metals by means of electricity
is characterized thereby, that the heat requisite for the smelting is produced by
conducting an electric current through a layer of molten material of small
conductivity an electrolyte-which owing to the resistance offered by it to the
electric current, is thereby heated so greatly, that the metal, which when for
instance iron, supplied from above and owing to its greater specific weight, sinks
through this layer, obtains the temperature wanted for the smelting. In order
that the current may pass a sufficiently long way and suitable dimensions may be
given to the furnace the current must pass above or beneath a bridge, the two
pole pieces being inserted at each side of said bridge and under the said electrolyte.
The two pole pieces can be made of the same metal as that which is to be molten,
or the one pole piece is made of carbon or the like and the other of metal. As
these pole pieces are situated under the molten layer of small conductivity they
(or it) will during the process become slightly fused, so as to be transformed in
the produced molten metal. As the pole usually is counted down to the transition
of the metallic conductor into the electrolyte, (here the layer of small conductivity)
the two pole pieces (or at least one of them) will thus consist of molten metal.
This is one of the characteristic features of the method in question. If it be
desired to make the process continuous the metal is supplied continuously, and the
produced metal as well as the layer of small conductivity are by suitable means
maintained automatically at a constant or practically constant height.
My method is carried out in this manner, that the molten electrolyte is introduced
into the furnace and heated still more by closing an electric current through the
same. It may be observed here, that it may be convenient to use alternating
currents for the purpose, in order that the electrolyte may not be decomposed.
When the temperature has become sufficiently high, the metal is added in some
form. If the metal is of a greater specific weight than the electrolyte it is
introduced at the top of the furnace and sinks down through the electrolyte,
during which passage it smelts and becomes fused at the bottom of the furnace,
from which it is removed in some manner. If on the contrary the metal is of less
specific weight than the electrolyte, the metal is introduced from below and ascends
through the electrolyte, so as to become fused at the top of the furnace from which
It is removed.
The said bridge, which holds the poles separated one from another, is in the first

page_text: mentioned case placed in the lower part of the furnace. In the latter case it is
situated in the upper part of the furnace, for instance suspended from the roof.
Dated this 2nd day of September 1892.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.
COMPLETE SPECIFICATION.
Method of Smelting or Heating Iron or other Metals by Means of
Electricity, and Apparatus therefor.
I, CARL GUSTAF PATRIK DE LAVAL, Dr. Phil, of No. 16* Handtverkaregatan,
Stockholm, Sweden, 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:―
The present method of smelting or heating iron or other materials by means of
electricity is characterized thereby that the heat requisite for the smelting
produced by conducting an electric current through a layer of molten material of
slight conductivity-an electrolyte-which owing to the resistance offered by it to
the electric current is thereby heated so greatly that the metal, which, when for
instance iron, is supplied from above, and owing to its greater specific weight,
sinks through said layer obtains the temperature required for the smelting during
its passage through this layer. The two pole pieces are inserted in the furnace at
each side of a transversal bridge, made of some refractory matter, and under the
said electrolyte so that the current must pass above or beneath this bridge and
through the electrolyte, in order to arrive from one pole to the other. As these
pole pieces. are situated under the molten layer of slight conductivity they will
during the process become slightly fused so as to be transformed in the molten
metal. As the pole usually is reckoned up to the point of contact between the
metallic conductor and the electrolyte (in this case the layer of slight conductivity)
the two poles will thus in the present method consist of molten metal. This is
one of the characteristic features of the method in question. If it be desired to
make the process continuous the metal is supplied continuously, and the produced
metal as well as the above situated layer of slight conductivity are maintained
automatically at a constant or practically constant height.
The smelting is carried out in this manner that the molten electrolyte is introduced
into the furnace and heated still more by closing an electric current through the
same. It may be observed here that it may be convenient to use alternating
currents for the purpose, in order that the electrolyte may not be decomposed.
When the temperature has been raised sufficiently high, the metal is added in some
form either as free metal or as a metallic combination which latter in the furnace
is reduced to free metal. If the metal or metal combination is of a greater specific
weight than the electrolyte it is introduced at the top of the furnace and sinks
down through the electrolyte, during which passage it smelts and gathers in fused
state at the bottom of the furnace, from which it is removed in some suitable
manner. If, on the contrary, the metal or metal combination is of less specific
weight than the electrolyte, it is introduced from below and ascends through the
electrolyte so as to gather in fused state at the top of the furnace from which it
is removed. The said bridge which holds the poles separated one from another is
in the first mentioned case placed in the lower part of the furnace. In the latter
case it is situated in the upper part of the furnace, for instance suspended from
the roof.
In the accompanying drawing Figs. 1-4 show in vertical and horizontal
sections as an example a furnace for carrying out the above indicated method of
smelting.

page_text: A is the furnace into which, when iron is to be molten spongy iron for instance
inay be introduced through the hole B. In the lower part of the furnace there
is located a bridge C of some refractory matter extending transversally across the
furnace on each side of which bridge the pole pieces D and E, which are connected
with a source of electricity, are secured. These pole pieces consist in this example
of iron bars which are inserted at the bottom of the furnace in the cavity between
the bridge C and the wall of the furnace as distinctly shown in the drawing.
F and Gare two outlets for the metal which are disposed as overflows so that
the metal flows out when it has risen to a certain height. H is a hole in the wall
of the furnace designed to maintain the molten layer of slight conductivity—the
electrolyte-at a constant height. As electrolyte may in the present example,
thus for smelting iron, be used magnetic iron ore. For smelting zinc or lead ores
sulphide of iron is used as electrolyte. The bridge C is represented hollow and a
flattened pipe C₁ passes through this cavity in order to effect the requisite
refrigeration of the bridge by conducting water or the like through the mouth
piece C. C³ is the outlet of the water or the refrigerating liquid.
When the furnace is to be put in action the molten electrolyte I is poured in
through the hole B, and the pole pieces DE are connected with the generator of
electricity. The current then passes through the electrolyte and over the bridge C
thus heating the electrolyte still more. The metal is now added in some form
sinks down through the electrolyte while being heated by the latter to the
temperature of smelting and gathers when fused on the bottom of the furnace.
The pole pieces D and E sinelt also a little so that the poles will consist of molten
metal. As metal is constantly supplied sinks down through the layer I and gathers
on the bottom of the furnace, this molten layer ascends at last so that metal flows
out through the outlets F and G. Their height above the bottom of the furnace
determines thus the distance between the two poles or the so called pole level and
consequently the way which the current must pass through the electrolyte from one
pole to the other. In the same way the height of the electrolyte layer I is
automatically regulated by the hole H.
If a metal is to be brought in fusion the specific weight of which is less than
that of the electrolyte a furnace similar to the one described may be employed, but
reversed; that is having the bridge suspended from the roof. The electric current
must then pass beneath the bridge and through the electrolyte in order to arrive
from one pole to another.
The above method and furnace can also be employed to overheat a metal. The
metal is in this case introduced in fusion and it obtains the overheat when
passing through the electrolyte layer which communicates its heat to the molten
metal.
Though only metals are mentioned here above which may be molten or heated
in the described manner, the method may also be employed for other materials
which are desired to be smelted or heated.
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 method of smelting or heating iron or other materials by means of
electricity, whereby the heat requisite to the smelting or heating is generated by
on electric current to pass above or beneath a bridge and through a molten layer of
slight conductivity-an electrolyte-while the material to be molten or heated is
introduced in some suitable form and sinks or ascends through the said layer
substantially as set forth.
2. In an electric smelting furnace for carrying out the method indicated in
Claim 1, a bridge of some refractory matter across the furnace in combination
with two pole pieces situated at each side of said bridge substantially as set
forth.

page_text: 3. In an electric smelting furnace of the kind indicated in Claim 2 the arrange-
ment of the outlets for the metal as overflows for regulating automatically the
distance between the two poles substantially as set forth.
4. In an electric smelting furnace of the kind indicated in Claim 2 the appli-
cation of a hole in the furnace wall for regulating automatically the height of 5
the molten layer of slight conductivity aboves the poles, substantially as
set forth.
Dated this 2nd day of June 1802
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.