Process for Reducing Certain Metallic Oxides by Means of Amalgams of Alkaline Metals.
Year: 1895

page_text: Date of Application, 20th June, 1895
omplete Specification Left, 20th Mar., 1896-Accepted, 16th May, 1896
PROVISIONAL SPECIFICATION.
A Process for Reducing Certain Metallic Oxides by Means of
Amalgams of Alkaline Metals.
I, LUDWIG MOND, of 20 Avenue Road, Regent's Park, in the County of
London, Manufacturing Chemist, do hereby declare the nature of this invention
to be as follows:-
It is well known that alkaline chlorides, such for instance as sodium chloride,
can be electrolytically decomposed in a cell containing mercury, the chlorine
being given off and the alkaline metal being collected in the mercury with which
it forms an amalgam.
My invention relates to the application of such amalgams, produced in this way
or otherwise, for the reduction of such inetallic oxides as are soluble in caustic
alkali. For this purpose, into a cell containing an alkali solution of the metallic
oxide, such for instance as zinc oxide in caustic soda solution, I introduce the
amalgam, and also a piece of metal such as iron or zinc, which I connect to the
amalgam either directly or by a conductor external to the solution. An electrical
action ensues, the sodium becoming oxidised and the zinc oxide becoming reduced,
its zinc being deposited on the piece of metal, which, in order that the deposit may
be sound and pure, is preferably kept in motion during the action. A convenient
arrangement for this purpose is to make the metal which receives the deposit in
the form of a cylinder, or the like, and to cause it to revolve in the cell. The
sodium oxidised adds to the caustic soda solution in the cell, and this solution, when
the zinc is more or less eliminated, may be concentrated or otherwise treated, or
may be used for solution of zinc oxide to be operated on as described.
In the conductor, which may be arranged to connect the amalgam with the metal
that receives the deposit, there may be introduced an electric motor or other
consumer of the excess of electric energy developed in the cell.
In operating as above described for the oxidation of the sodium and the
reduction of the zinc, there is no evolution of hydrogen, and consequently there is
no loss of mercury, nor noxious effects such as cccur when vapour of the mercury
is carried off by the hydrogen.
There may be a number of reducing cells such as I have described, operating
simultaneously or in rotation, and they may be connected to electrolytic cells in
which the chloride is decomposed and the amalgam is formed, the mercury which
is cleared from the alkaline metal in the reducing cells being returned to the
decomposing cells to receive a fresh supply and then to be treated in the reducing
cells.
Although I have mentioned sodium and zinc as the metals dealt with, obviously
instead of sodium, potassium may be employed, and instead of zinc, other metals
the oxides of which are soluble in caustic alkali, may be treated.
Dated this 20th day of June 1895.
ABEL & IMRAY,
Agents for the Applicant.

page_text: A Process for Reducing Certain Metallic Oxides by Means of
Amalgams of Alkaline Metals.
I, LUDWIG MOND, of 20 Avenue Road, Regent's Park, in the County of
London, Manufacturing 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:-
It is well known that alkaline chlorides, such for instance as sodium chloride,
can be electrolytically decomposed in a cell containing mercury, the chlorine being
given off and the alkaline metal being collected in the mercury with which it forms
an amalgam.
My invention relates to the application of such amalgams, produced in this way
or otherwise, for the reduction of such metallic oxides as are soluble in caustic
alkalies. For this purpose, into a cell containing an alkaline solution of the
inetallic oxide, such for instance as zinc oxide in caustic soda solution, I introduce
the amalgam, and also a piece of metal such as iron or zinc which is electronegative
relatively to the amalgam. I connect this piece of metal to the amalgam either
directly or by a conductor external to the solution. An electrical action ensues,
the sodium becoming oxidised and the zinc oxide becoming reduced, its zinc being
deposited on the piece of metal which acts as a cathode, and which, in order that
the deposit may be sound and pure, is preferably kept in motion during the
action.
A convenient arrangement for this purpose is to make the metal which
receives the depozit in the form of a cylinder, or the like, and to cause it to
revolve in the cell. The oxidation of the sodium and reduction of the zinc oxide
can be promoted by reinforcing the current produced in the cell by a current from
a convenient external source of electricity. The sodium oxidised adds to the
caustic soda solution in the cell.
After the zine has been more or less eliminated from this solution, part of it may
be concentrated to obtain solid caustic soda, or may be otherwise utilised, while
the rest may be used for solution of zinc oxide to be operated on as described. In
the conductor which may be arranged to connect the amalgam with the piece of
metal that receives the deposit there may be introduced an electric motor or other
consumer of the excess of electric energy developed in the cell.
In operating as described for the oxidation of the sodium and the reduction of
the zinc, there is no evolution of hydrogen, and consequently there is no loss of
mercury, nor any noxious effects such as occur when vapour of mercury is carried
off with hydrogen.
There may be a number of reducing cells such as I have described, operating
simultaneously or in rotation, and they may be connected to electrolytic cells in
which the chloride is decomposed and the amalgam is formed, the mercury which
is cleared from the alkaline metal in the reducing cells being returned to the
decomposing cells to receive a fresh supply of the alkaline metal and then to be
treated again in the reducing cells.
Although I have mentioned sodium and zinc as the metals dealt with, obviously
instead of sodium, potassium may be employed, and instead of zinc, other metals
the oxides of which are soluble in caustic alkali, may be treated.
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 :-
The herein described process for reducing a metallic oxide which is soluble in a
caustic alkali, by introducing into its solution in the caustic alkali an amalgam of

page_text: the same alkaline metal as that in the caustic alkali with mercury, and a piece
of suitable metal as cathode electrically connected to the amalgam, whereby the
alkaline metal of the amalgam is oxidised producing caustic alkali and the dissolved
oxide is reduced, its metallic base being deposited on the cathode.
Dated this 19th day of March 1896.
ABEL & IMRAY,
Agents for the Applicant.