Year: 1898

page_text: I, VICTOR ISIDORE FEENY, of 60, Queen Victoria Street, London, Chartered Patent
Agent, do hereby declare the nature of this invention, a communication to me from
Hermann Becker, of 5, Rue Guy Patin, Paris, France, Chemist, to be as follows:-
This invention relates to the cathodes used in electrolytical processes and has for
object to afford surfaces from which the deposits obtained by electrolysis may easily
be detached, either by breaking off or away if the deposit be thick enough, or by
brushing if it be too thin.
My arrangement of cathode may be used for both the refining of metals and the
precipitation of metals in solution which have served to lixiviate minerals, and for
the manufacture, by electrolytic deposition, of articles of, various shapes.
These cathodes are of metal covered with a layer of sulphur. This latter body or
composition is formed by direct combination of the metal of the cathode with sulphur.
This combination may be produced in any manner whatever. The metal chosen for
the cathodes should be able to form by combination with the sulphur, a sulphide in-
soluble in the electrolytic bath in which the cathodes are to be employed. It is not
necessary that the said sulphide should be indecomposable.
The cathodes in question may also be of any suitable substance and be coated with
a suitable metal, or may be of any convenient metal coated by any of the known
processes, with a layer of a metal conforming to the desired conditions. The super-
ficial sulphuretting of the metal of the cathodes or of the metallic coating of these
latter, may be formed or caused either by rubbing them with sulphur moistened with
water, or by immersing them in or coating them with a solution of sulphuretted
hydrogen, with an alkaline sulphide or with a sulphide of an alkaline earth, or by any
other suitable means using either heat or cold. The layer of sulphur thus produced
by the reaction between the metal of the cathode and the element sulphur, is very
adhesive to the metal.
A layer or coating of the desired thickness may be obtained by varying the dura-
tion and strength of the reaction.
If the resulting surface is polished and bright, the metal deposited thereon by the
action of the electric current is similarly polished and bright upon its face in contact
therewith. Accordingly by selecting for cathodes, metallic moulds or cores super-
ficially sulphuretted and polished, I may obtain articles having a polished and bright
surface, and made of gold, silver, nickel, or any other metal deposited by the electric
current. I can also obtain objects or articles of different alloys or metals or even
articles formed of several layers or superposed thicknesses of different metals. To
produce objects formed of several layers of metals, a series of electrolytic baths must
be used. To impart a polished and bright surface to the cathodes, the metal of the
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page_text: cathodes may be first polished and then sulphuretted, or I may first strongly or
thickly sulphuret the cathode and then polish this sulphur coating.
When the electrolytic bath in which the cathodes are to be used, can decompose
the sulphur with which the latter are covered, they are connected to the negative
pole or the source of electricity before being placed in the bath. In heavy work
electro-metallurgy, the cathodes will be placed in the electrolyzers and be connected
to the negative pole of the source of electricity before admitting the electrolyte into
the baths.
Cathodes prepared according to my process can serve for a great number of opera-
tions before it is necessary to coat them with a new layer of sulphur.
The metals which may be used for the preparation of the cathodes are, all those
capable of forming a sulphide insoluble in the electrolytic bath and not offering too
great resistance to the electric current.
In certain cases, and according to the metals used, the sulphuretting may be re-
placed by an oxidation, a chloridation, bromidation, iodation, etc.
That is to say I may form, on the surface of certain metals and by reaction between
the metal and a suitable element, a layer or coating conforming to the requisite
conditions; that is to say the said layer should strongly adhere to the metal of the
cathode, but the metals electrolytically precipitated thereon should not adhere
thereto; this layer should also be a good conductor and be insoluble in the
electrolyte.
In heavy electro-metallurgy it is preferable to make use of ordinary metals, iron,
copper, lead etc. etc.
The metal selected should be as near as possible the same as the metal to be
precipitated.
1
In the treatment of cyanide and argentiferous solutions the cathodes are preferably
made of sheets of iron, copper or lead, superficially sulphuretted as above described,
or of sheet-iron, tinned, coppered or coated with lead by any suitable process and
afterwards superficially sulphuretted. Having regard to the large surface of cathodes
used in the electrolytic treatment of cyanide auriferous or argentiferous solutions
or in any other chemical solution which has served for the lixiviation of gold- or
silver-bearing minerals, it may so happen that the layer of precious metal is much
too thin to be broken off or away and should then be removed by energetic
brushing.
A coating of another metal (e.g. copper) may also be electrolytically deposited on
the layer of precious metal so that there may be formed upon the cathode a layer of
metals sufficiently thick to be broken off. Also I may first deposit a coating of
ordinary metal on the sulphuretted cathodes before proceeding with the electro
deposition of the gold or of the silver. In this latter case, the coating of
precious metal will be above the layer of ordinary metal instead of being under-
neath.
By adding for example a salt of mercury to the solution to be electrolysed, gold or
silver will be deposited in the form of amalgams of a more friable nature than pure
gold or silver, so that the coating can be more easily removed by brushing. By
adding to the solution to be electrolysed a salt of copper I obtain upon the cathodes
a layer of gold or of silver alloyed or mixed with copper; so that if the quantity of
copper deposited be fairly heavy, the layer of metal will be thick enough to be broken
off or away.

page_text: Improvements in Electrolysis and Cathodes therefor.
I, VICTOR ISIDORE FEENY, of 60, Queen Victoria Street, London, Chartered Patent
Agent, do hereby declare the nature of this invention, which is a communication
to me from Hermann Becker, of 5, Rue Guy-Patin, Paris, France, Chemist, and in
what manner the same is to be perforined, to be particularly described and
ascertained in and by the following statement :-
The invention hereinafter described relates to the preparation and use of cathodes
enabling the layer of metal deposited under the action of the electrolytic current to
be easily detached therefrom. These cathodes are capable of being used both for
refining metals and for precipitating metals from solutions which have served for
the lixiviation of ores and also for the manufacture by electro-deposition of articles
of various forms.
These cathodes are of metal covered with a polished layer of sulphide of the same
metal formed by the combination of the metal of the cathode with sulphur. The
cathodes may be of any suitable metal coated by one of the ordinary processes with a
layer of another metal capable of forming by combination with sulphur a sulphide
insoluble in the electrolytic bath. The sulphuration of the metal of the cathode may
be produced in any suitable manner either by rubbing it with powdered sulphur or
by exposing it to the vapour of sulphuretted hydrogen, or by immersing it for some
time in a solution of alkaline sulphides or alkaline earth sulphides.
Whatever method of sulphuration is employed the layer of sulphide obtained must
be polished; the more it is polished, the more the metal electrolytically deposited
thereon will be capable of being freely detached. In order to render the surface of
the sulphuretted cathodes polished and brilliant the metal may be first polished and
then slightly sulphuretted by rubbing it with powdered sulphur or it may be first
sulphuretted strongly in any suitable manner and then the sulphide coating polished.
The first method of operation is principally employed for galvano-plastics, the second
only for the larger electro-metallurgy, that is to say for refining inetals and treating
ores. The polish of the layer of metal deposited by electrolysis is precisely the same
as that of the cathode on which this deposit has been formed. These cathodes, when
they are intended for the preparation of polished articles, are preferably of polished
silver or silvered metal. In this case the sulphuration of the cathodes is produced
mechanically by rubbing them with flower of sulphur or precipitated sulphur. This
method of producing the sulphuration preserves the polish of the silver and gives a
layer of sulphide excessively thin and even. Silver sulphuretted in this way has a
slight golden tinge. A skin or coating of sulphur so thin as to be imperceptible to
the eye and not to modify the colour of the silver suffices, however to prevent the
adherence of metals deposited. I have selected silver as the metal of which to make
these cathodes, as being the metal which is capable of taking the finest polish, the
least oxidisable and the best conductor of electricity. It also furnishes a sulphide of
high conductivity and which does not oxidise in the air. Silver is also the most
electropositive metal which can be made use of and the easiest to coat regularly with
sulphide whilst preserving its polish. By means of these cathodes objects having
the polish of silver may thus be obtained in metals difficult to polish and the said
objects may be of pure metal or of alloys or be formed by the superdeposition of
several layers of different metals.
In large electro-metallurgy where it is not sought to obtain the polish of the metal
deposited, but simply to recover the latter and to re-utilise the cathodes, these latter
are formed of ordinary metals instead of silver or silvered metal, but it is essential to
obtain as polished a layer of sulphide as possible so as to be able to freely detach

page_text: therefrom the metal deposited. The sulphuration may be produced in various ways
but the mechanical operation with flower of sulphur or precipitated sulphur gives the
best results and is the most convenient to use because there is no release of
sulphuretted hydrogen. In the electrolytic treatment of cyanide auriferous and
argentiferous solutions arising from the lixiviation of gold and silver ore, these
cathodes are preferably formed of sheets of iron, copper, lead, nickel or the like or
sheets of iron, tinned, coppered, nickeled or the like, the said sheets being
sulphuretted and polished as has been herein before described. It may happen in the
electrolytic treatment of solutions having served for the lixiviation of gold and silver
ores, that the layer of precious metal is too thin to be pulled off and must be
removed by vigorous brushing. This drawback only arises in the treatment of gold
ore and not in that of silver ore where the quantity of metal is always sufficiently
great to yield deposits thick enough to be stripped off. In the case of gold ore,
in order to collect the ore deposited on the cathodes, a layer of another metal,
such as copper for instance, may be deposited electrolytically on this gold, in order
to have a sufficiently thick metal layer to be stripped off. It is needless to state
that a layer of an ordinary metal may also be deposited first on the cathodes
before proceeding to the electro-deposition of the gold. In this case the layer of
precious metal will be above the layer of ordinary metal instead of being below
A salt of quicksilver, copper or silver may also be added to the auriferous
solution before its passage into the electrolysing apparatus so that the gold is
deposited in the form of an alloy and forms consequently a thicker layer.
it.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is
1. Metallic cathodes of various shapes coated with a layer of sulphide produced by
superficial sulphuration of the cathode, said sulphuretted layer being such that it
forms a polished surface, substantially as and for the purpose hereinbefore set
forth.
2. Silver or silvered cathodes of various shapes coated with a layer of sulphide
produced by superficial sulphuration of the cathode, said sulphuretted layer being
such that it forms a polished surface, substantially as and for the purpose hereinbefore
set forth.
3. Silver or silvered cathodes of various shapes coated with a polished layer of
sulphide of silver, said polished layer being obtained by rubbing the surface
of the cathodes with powdered sulphur, substantially as and for the purpose
hereinbefore set forth.
000