CA1037897A

CA1037897A - Electrochemical refining of metals

Info

Publication number: CA1037897A
Application number: CA112,480A
Authority: CA
Inventors: Peter K. Everett
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-05-11
Filing date: 1971-05-07
Publication date: 1978-09-05
Also published as: GB1354577A; FR2088488A3; DE2123279A1; ZA712915B; FR2088488B3; BR7103037D0; SE382805B

Abstract

Abstract Manganese dioxide ore is converted to purified manganese dioxide in an electrolytic cell having inert electrodes disposed on opposite sides of a porous diaphragm, the ore being located in the electrolyte but physically not in contact with the cathode.

Description

--1037~97 This invention relates to the electrochemical purification of man-ganese dioxide ore.
According to the present invention, there is provided a process for the purification of manganese dioxide ore in an electrochemical cell having an inert anode and an inert cathode disposed on opposite sides of a horiz-ontal porous diaphragm and immersed in an aqueous electrolyte containing an oxidation-reduction catalyst system, wherein manganese dioxide ore is located in the electrolyte on the cathode side of the diaphragm but physically out of contact with the cathode, which comprises applying a direct current potential between the anode and the cathode so that manganese ions are released from said ore and ionic manganese diffuses through the diaphragm and is oxidized at the anode depositing purified manganese dioxide.
The reactions which take place in the process of the invention may ~ ~ -be illustrated by the equations:
cathode: 2catalyst +2e ~ 2catalyst ore: MnO2 + 4H +2catalyst ~ Mn + 2H20 and anode: Mn + 2H20 ~ MnO2 + 4H + 2e The process, in one preferred embodiment of this invention, may be carried out by introducing the manganese dioxide ore to be purified into the bottom compartment of a chamber which forms part of the electrochemical cell and which is divided in two by the porous diaphragm. On the bottom of this compartment but physically out of contact with the ore, is the inert cathode.
The compartment may also contain means for slowly agitating ore introduced into this bottom compartment.
In the process of this invention the anode may be a rotating drum or rotating vertical disc. The manganese dioxide deposited at the enode may be removed from the rotating anode by means of a scraper.
The catalyst, (iron or other variable valence ions, oxygen and hydrogen ion) undergoes alternate oxidation and reduction and transfers elec- `
trons between the cathode and the ore. :
Although the ferrous - ferric couple ~Fe /Fe ) is probably the most important catalyst other catalysts may also be used. Examples of these ~ : . :
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~0378g7 are Cu /Cu , Co /Co , Ni /Ni and 2' The metal catalyst couples ean be provided by adding to the electrolyte a water-soluble salt of the metal in question, e.g. a water-soluble salt of iron III.
An example of an electrochemical cell in which the process of this invention can be performed is shown in the accompanying drawings:
Figure 1 is a longitudinal section of the electrochemical cell;
Figure 2 is a transverse section of the electrochemical cell in Figure 1.
In this example a charge of manganese dioxide ore 1 (usually a 2"
to 20" layer) is placed in a lead lined steel or other corrosion resistant tank 2. The tank is filled with the electrolyte 3 ~with a cation composition similar to the material being processed and containing iron III ions) and is heated to over 80C and preferably as close to boiling as possible.
A direct current potential is applied between a high surface area lead or graphite cathode 4 at the bottom and a rotating lead, graphite or titanium drum or vertical disc anode 5 at the top. Iron III is reduced to iron II at the cathode and diffuses upwards to the ore where the iron II re-duces the manganese ~q~to manganese II and is itself oxidised to iron III.
The manganese ions diffuse through a porous diaphragm 6 and deposit as man-ganese dioxide 7 on the rotating drum 5 from which the oxide is recovered by `~
scraper 8. Electrolyte is allowed to leave the tank through a filter set in the bottom and it may be used for the next batch.
The manganese dioxide ore is physically separated from the negative electrode, for example by means of a mesh 10. The initially deposited man-ganese dioxide may be returned from the anode to the top of the diaphragm ~as shown in 9) to minimise thé diffusion of the ions of other metals to the anode depcsit.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the purification of manganese dioxide ore in an electrochemical cell having an inert anode and an inert cathode disposed on opposite sides of a horizontal porous diaphragm and immersed in an aqueous electrolyte containing an oxidation-reduction catalyst system, wherein man-ganese dioxide ore is located in the electrolyte on the cathode side of the diaphragm but physically out of contact with the cathode, which comprises applying a direct current potential between the anode and the cathode so that manganese ions are released from said ore and ionic manganese diffuses through the diaphragm and is oxidized at the anode depositing purified manganese di-oxide.

2. A process as claimed in claim 1 wherein the electrolyte is at a temperature of over 80°C.

3. A process as claimed in claim 1 or 2 wherein the oxidation-reduction catalyst system is a water-soluble salt of iron III.

4. A process as claimed in claim 1 or 2 wherein the manganese dioxide ore to be purified is located in the cathode compartment below the porous diaphragm.

5. A process as claimed in claim 1 or 2 wherein the manganese dioxide ore to be purified is located in the cathode compartment below the porous diaphragm and the oxidation-reduction catalyst system is a water-soluble salt of iron III.