Abstract: An electrolysis cell (10) 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 (14) 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 (18) within the electrolysis section for effecting the electrolysis; a metal recovery section (15) 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 (25) 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.

Abstract: An electrolytic cell for the recovery of metal from a molten electrolyte and an electrode assembly for use in such a cell. The cell (10) comprises an electrode assembly consisting of an anode (17), a cathode (19) and one or more bipolar electrodes (18) disposed between the anode and the cathode so as to form interpolar spaces (16) in which electrolysis occurs. In the electrode assembly, the bipolar electrode (if there is only one) or the innermost bipolar electrode (if there are more than one) substantially surrounds the anode and forms a single mechanical and electrical entity. The cathode in turn preferably substantially surrounds the one or more bipolar electrodes. The electrode assembly comprising the cathode and bipolar electrode(s) is preferably unitary, forming an electrode cassette that can be assembled outside a cell and then introduced into, or withdrawn from, the cell as a single self-supporting unit.

Abstract: 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.

Abstract: 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.

Abstract: 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.