Alcan International Limited

Alcan Research and Development Limited

Meine Vandermeulen

Adam J Gesing

Edward L Cambridge

John McIntyre

Olivo G Sivilotti

Raman Radha Sood

David K Creber

George C Holywell

Junkichi Iseki

Jorgen Christensen

Pasquale Ficara

Charles J Rogers

Thomas P DeAngelis

An electrolysis cell ( ) for producing a molten metal having a density less than a density of a molten electrolyte used for producing the metal in the cell. The cell includes a section ( ) for the electrolysis of a salt of the the metal contained in a molten electrolyte to form droplets of the metal in molten form contained in the electroylte; electrodes ( ) within the electrolysis section for effecting the electrolysis; a metal recovery section ( ) for separation of the metal from the electrolyte to form a molten metal layer, having an upper suface, floating on an upper surface of the molten electrolyte; a tapping device for periodically removing molten metal from the cell; and a reservoir ( ) for withdrawal and temporary holding of molten metal separated from the electrolyte in the metal recovery section. The reservoir has a means to remove liquid from the reservoir without permanently removing the liquid from the cell. The reservoir has a top, sides and bottom and has one or more openings in the top or sides of the container communicating with the metal recovery section. At least part of the opening(s) is maintained below the upper surface ( ) of the metal layer during at least part of normal cell operations, and all of the opening(s) is kept above the upper surface of the electrolyte in the metal recovery section for at least part of the normal cell operation. The sides and bottom are otherwise closed to prevent metal or electrolyte from freely flowing between the metal recovery section and the reservoir. The cell containing such a reservoir may accommodate high rates of metal production without unduly increasing cell size or requiring high heating requirements.

Molten salt electrolytic cell having metal reservoir

Multi-polar cell for the recovery of a metal by electrolysis of a molten

In an electrolytic reduction cell in which molten metal is produced by electrolysis of a molten electrolyte, less dense than the molten metal product, the molten product metal collects at the bottom of the cell. A filter is provided at this location and is constructed from a material which is resistant to attack by both the molten metal and molten electrolyte, and which is wetted by the molten metal, but not by the electrolyte. By correcting sizing of the passage or passages in the filter molten metal product can be drawn out of the cell without simultaneous withdrawal of molten electrolyte. In the case of a cell for the production of aluminium the filter is preferably constructed from titanium diboride.

Electrolytic reduction cells

In an electrolytic reduction cell for the production of molten metal, particularly aluminium, by electrolysis of a less dense salt monolayer of ceramic shapes is located on the floor of the cell. Such shapes are formed of a ceramic material, wettable by molten aluminium, but not wettable by the cell electrolyte. The spacing between adjacent shapes and/or the apertures in individual shapes is selected such that interfaced surface forces prevent entry of electrolyte between the shapes. The shapes may be tiles, honeycombs, cylinders, tubes, balls etc. The product metal may be collected in a sump for periodic withdrawal from the cell or withdrawn continuously or at short intervals through a selective filter that permits passage of molten metal, but not of molten cell electrolyte, at low withdrawal rates.

In a process for production of aluminium metal described in U.S. Pat. No. 4,099,959 carbon monoxide gas is evolved at very high temperature through reaction of aluminium carbide and alumina in a high temperature zone of the system. This gas is cooled by contact with a molten alumina slag at a lower temperature to cause back reaction of contained aluminium suboxide and Al vapor and consequent heat transfer to the contacted molten alumina slag. A body of molten alumina slag is maintained in a pretreatment zone, to which carbon and alumina feed are introduced and the carbon monoxide gas is led into the pretreatment zone. Excess slag, resulting from such introduction of feed and from gaseous back reaction, spills over into a low temperature zone of the system to augment the circulating slag stream.

Carbothermic production of aluminium

Growing community of inventors

Kingston, Canada

Meine Vandermeulen