Loading patent…
AssigneeRio Tinto Alcan International Limited
InventorsThinh Nguyen, Frank Schnyder, Vittorio De Nora
Estimating the term…
A cell for electrowinning a metal, in particular aluminium, from a compound thereof dissolved in an electrolyte (30) comprises an anode (40) and a cathode (10,11) that contact the electrolyte (30), the cathode (10,11) being during use at a cathodic potential for reducing thereon species of the metal to be produced from the dissolved compound. The electrolyte (30) further contains species of at least one element that is liable to contaminate the product metal (20) and that has a cathodic reduction potential which is less negative than the cathodic potential of the metal to be produced. The cell further comprises a collector (50) for removing species of such element (s) from the electrolyte (30). During use the collector (50) is at a potential that is: less negative than the cathodic potential of the produced metal (20) to inhibit reduction thereon of species of the metal to be produced; and at or more negative than the reduction potential of the species of said element(s) to allow reduction thereof on the collector (50). The cell is so arranged that species of said element(s) are reduced on the collector (50) rather than on the cathode (10,11) so as to inhibit contamination of the product metal (20) by said element(s).
A cell for electrowinning a metal from a compound thereof dissolved in a molten salt electrolyte, in particular aluminium from dissolved alumina, said cell comprising an anode and a cathode that contact the molten electrolyte, the cathode being during use at a cathodic potential for reducing thereon species of the metal to be produced from the dissolved compound, the electrolyte further containing species of at least one element that is liable to contaminate the product metal and that has a cathodic reduction potential which is less negative than the cathodic potential of the metal to be produced,
The cell of any preceding claim, comprising a means for supplying to the conductive collector surface a current for reducing species of said element(s) on the conductive collector surface during use.
The cell of any preceding claim, wherein the electrolyte contains dissolved product metal and/or another metal that during use is/are oxidised on the conductive collector surface to pass an electric charge that reduces species of said element(s) on the conductive surface.
The cell of any preceding claim, wherein the conductive surface of the collector is made of carbon.
The cell of any preceding claim, wherein the species of said element(s) comprise species of at least one metal selected from nickel, iron, copper, cobalt, titanium, chromium, manganese, yttrium, cadmium, tin, antimony, gold, platinum, silver, cerium, palladium, ruthenium, tungsten, bismuth and lead.
The cell of any preceding claim, wherein the species of said element(s) comprise species of at least one metalloid or non metal such as sulphur.
The cell of any preceding claim, wherein the conductive collector surface is formed by one or more elongated members.
A method of electrowinning a metal in a cell as defined in any preceding claim, comprising:
A cell for electrowinning aluminium from alumina dissolved in a molten electrolyte, comprising an anode and a cathode that contact the molten electrolyte, the cathode being during use at a cathodic potential for reducing thereon aluminium species from the dissolved alumina, the electrolyte further containing species of at least one element that is liable to contaminate the product aluminium, wherein the cell further comprises a collector for removing species of said element(s) from the electrolyte, said collector having a surface in contact with the molten electrolyte, the cell being so arranged that species of said element(s) dissolved in the molten electrolyte are collected on the collector surface rather than on the cathode so as to inhibit contamination of the product aluminium by said element(s).
A cell for electrowinning a metal from a compound thereof dissolved in a molten electrolyte, said cell comprising an anode and a cathode that contact the molten electrolyte, the cathode being during use at a cathodic potential for reducing thereon species of the metal to be produced from the dissolved compound, the electrolyte further containing species of at least one element that is liable to contaminate the product metal and that has a cathodic reduction potential which is less negative than the cathodic potential of the metal to be produced,
Dependencies are inferred from the claim text.