Electrolytic Process for Extracting Metals from their Halogen Combinations.
Year: 1898

page_text: Date of Application, 30th July, 1898-Accepted, 22nd Oct., 1898
COMPLETE SPECIFICATION.
Electrolytic Process for Extracting Metals from their Halogen
Combinations.
I, DR. EMIL HILBERG, of Schellingstrasse 16, Berlin, Germany, Chemist, 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 object of this invention, is an improved electrolytic process for extracting
metals from their halogen combinations.
The invention consists, substantially, in, that during the electrolysis and the
heating carried on therewith, the molten mass, is covered with a material that is
capable of resisting the temperature applied, and at the same time allows of com-
munication between the gas evolved by the molten mass and the space above the
same. If a large number of electrodes be employed, a covering material should
be selected which is, moreover, non-conducting in regard to electricity.
A modification of the invention consists in that the decomposition is effected
with simultaneous production of a vacuum above the molten material or with
introduction above the same of a gas having no affinity for (indifferent to) the
products of decomposition. As material for the covering layer, asbestos is specially
to be recommended.
The covering of the molten mass by means of a covering layer of the kind
indicated secures a considerable number of new technical effects and increases
the productiveness of the electrolytic process considerably.
In a physical-mechanical view, the object of the comparatively rigid and gas-
permeable covering layer is to secure complete homogeneity and calm (or rest)
for the molten mass, by entirely preventing any foaming or fluctuating. It is
clear that in such a condition of the material, the electrolytic process proceeds
all the more uniformly and effectively, whilst at the same time, the electrodes
immersed in the molten mass are protected against any physical (mechanical)
damage from shocks or concussions. In consequence of the incombustible nature
of the covering layer, these advantages are retained during the whole period of
decomposition.
As regards the consumption of current, a non-conducting layer secures the
advantage of the greatest and most effective use of the current, particularly when
a large number of electrodes is employed. For, were the layer composed of con-
ducting material, there would with the large number of electrodes, be a large
quantity of current flowing uselessly through the covering layer, and the electrodes
be worn out to no purpose, whilst in the present case, the current from the anodes
to the cathodes merely passes through the molten material, fully used up, and
the electrodes are not needlessly (ineffectually) worn out.
In a chemical point of view, finally, the indicated covering layer effectually
prevents oxydation during the electrolysis, as it forms a porous partition, through
which the gases arising from the molten mass can escape without hindrance,
whilst the air above the covering layer is kept out of contact with the molten

page_text: mass, and prevented by the gas escaping from the same from passing through
the covering layer. By simultaneously producing a vacuum or expelling the
air with the aid of a gas indifferent to (having no affinity for) the products of
decomposition, this effect of the covering layer can, if necessary, be increased.
In order that the process may be made continuous, it is desirable that the
celting and the decomposition be carried out in separate vessels in such a
manner that, whilst the melting is proceeding in the one vessel, the decomposition
of the previously melted material is effected in the other vessel.
As an example of the carrying out of the new process, it may be applied to the
production of magnesium from carnallite. The carnallite is melted and the
iuolten material brought into the decomposing vessel, covered up with a covering
layer of asbestos. Hereupon, the vessel is closed air-tight, and current conducted
through the material, the heating being simultaneously carried on. As soon as
the appearance of chlorine vapours indicates that the electrolysis has commenced,
a vacuum is created in the vessel and thus a formation of magnesium oxide
effectually prevented during the decomposition which is then proceeding.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
1. An electrolytic process for extracting metals from their halogen combina-
tions, which substantially consists in that the molten material is kept covered up,
during the period of decomposition, with a material that resists the temperature
applied.
2. A method of carrying out the process mentioned under Claim 1, consisting
in that the molten mass is exposed to the action of a large number of electrodes
and a refractory and electrically non-conducting material, preferably asbestos,
is used as covering layer.
3. A modification of the process mentioned under Claims 1 and 2, consisting
in that the decomposition is effected with simultaneous production of a vacuum
above the molten material or with introduction above the same of a gas having
no affinity for (indifferent to) the products of decomposition.
4. Carrying out the process according to Claims 1, 2, 3 in separate vessels for the
melting and for the decomposition.
Dated this 30th day of July 1898.