An Improved Method of Producing Zino from Blende by Means of Electrolysis.
Year: 1892

page_text: Date of Application, 22nd Nov., 1892-Accepted, 4th Mar., 1893
An Improved Method of Producing Zino from Blende by Means of
Electrolysis.
We, GUNNAR ELIAS CASSEL, of 49 Norrtullsgatan and FREDRIK ADOLF
KJELLIN, of 43-45 Sibyllegatan, both in Stockholm, Sweden, Engineers, 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 :-
This invention relates to a method of producing zinc from blende (sulphuret of
zinc) by means of electrolysis.
For this purpose an electrolytic vessel of the usual construction is employed.
The cathode consists of a plate of zinc or other suitable material not corroded
by the process, and the anode is made of iron or other analogous metal but not of
zinc. The electrodes are separated by a porous partition of clay or similar material.
The cathode is surrounded by a solution of a salt of zinc (for instance sulphate of
zinc), which has been produced from the blende by some chemical or metallurgical
operation preferably of such a nature as to convert the zinc contained in the blende
into a soluble salt. Thus the blende can be calcined in a furnace in such a manner
that the zinc becomes transformed into oxide or sulphate. In the former case, the
oxide is dissolved in sulphuric acid, and in the latter case, the sulphate of zinc is
dissolved in water. Or the blende may be dissolved in a strong acid, but this
method would be too costly for general adoption. The anode on the other hand
is surrounded by a solution of a salt, the positive component of which consists of
the same metal as the anode, the negative component being the same acid as that
which is contained in the salt of zinc to be electrolyzed.
On the passage of the current through the electrolyte, the zinc is precipitated
upon the cathode, an equivalent quantity of the anode becoming simultaneously
dissolved. The purpose of the metallic anode, soluble by the acid set free, is a
twofold one, viz.-partly to bind or take up the acid set free during the electro-
lysis of the salt of zinc, which otherwise would cause a development of oxygen
and hydrogen gas, and partly to diminish the potential difference between the
electrodes, which otherwise would be necessary for the decomposition of the salt.
If the acid set free during the electrolysis, is of such a nature as to form
insoluble salts with the anode, as, for instance, when the anode consists of iron and
the zinc is combined with sulphuric acid (so that a basic iron salt is formed), the
above-mentioned porous partition can be dispensed with, as the electrolyte remains
unaltered, the salts which are formed at the anode being insoluble and falling to
the bottom of the vessel without entering into solution. In such cases only one
solution, namely the solution of the salt of zinc intended to be electrolyzed is used,
into which both electrodes are then introduced.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
First. The production of zinc from blende or sulphuret of zinc by means of
electrolysis by first converting the ore into a soluble salt of zinc and then electro-
lyzing this salt in a bath wherein the cathode consists of zinc or other suitable
metal not corrodible by the process, and is separated from the anode by a porous
partition, and the auode consists of iron or analogous metal but not of zinc, and
wherein the electrolyte around the cathode consists of the soluble salt of zinc and
that around the anode of a solution of a salt, the positive component of which

page_text: consists of the metal used as anode, and the negative component of which consists
of the same acid as that contained in the salt of zinc to be electrolyzed.
Second. A modification of the method above claimed, which is intended to be
used in cases where the acid set free during the operation forms insoluble salts
with the anode, and wherein the porous partition is dispensed with and the cathode
, and the anode are both surrounded by the salt of zinc to be electrolyzed.
Dated the Twenty-second day of November 1892.
D. YOUNG & Co.,
11 & 12, Southampton Buildings, London, W.C.,
Agents for the Applicants.