Abstract: The present invention concerns an electrolysis tank for the production of aluminum by means of the Hall-Heroult process, which operates at above 250,000 amperes, in particular from 270,000 to 320,000 amperes.The connection between each riser (7) and the anodic bus bar (5) is made by way of flexible electrical conductors (8); the central riser (7C) is disposed on the axis of the series, the two intermediate risers (7B, 7D) and the two equally spaced lateral risers (7A, 7E) through which substantially equal current strengths flow are connected to six upstream cathodic collectors (3), two central collectors (3A, 3B) two intermediate collectors (3C, 3D) and two lateral collectors (3E, 3F), and three downstream cathodic collectors (4), a central collector (4A) and two lateral collectors (4B, 4C).Equipotential connections provide for balancing of the current between the different sections of the upstream and downstream collectors.

Abstract: The invention relates to an electrolysis tank for production of aluminum by electrolysis of alumina dissolved in a molten cryolite bath, by the Hall-Heroult process, between at least a carbon anode and an aluminum sheet covering a carbon cathode substrate. At the interface of the aluminum sheet and molten cryolite bath it comprises a floating screen, which is conductive of electric current, not connected to the carbon cathode substrate and free to move at least in the vertical direction.The floating conductive screen can extend over the entire interface or be limited to being perpendicular to each anode.The distance between each anode and the floating conductive screen can be reduced to about 20 mm.

Abstract: The invention concerns floating cathode elements which are intended for the electrolytic production of aluminum using the Hall-Heroult process in an electrolysis tank comprising a molten cryolite-base bath, between a carbon anode, and a cathodic layer of molten aluminum, said elements comprising at least one active cathode element (30) formed of electrically conductive refractory material such as titanium diboride and supported by an intermediate support (31) which is inert with respect to the liquid aluminum and the electrolyte, the mean relative density of the assembly of the acitve cathode element and the inert intermediate support being lower than the relative density of the liquid aluminum under the normal conditions of operation of the electrolysis tank.

Abstract: A process and apparatus for controlling the rate of introduction and the content of alumina to a tank for the production of aluminium by the electrolysis of dissolved alumina in a cryolite-base bath, the upper part of which forms a solidified crust, and wherein the alumina content is maintained within a narrow range, of between 1% and 3.5%, wherein the alumina is introduced directly into the molten cryolite bath by way of at least one opening which is kept open in the solidified crust and the rate at which the alumina is introduced is modulated relative to variations in the internal resistance of the tank during predetermined periods of time, with alternation of the cycles of introducing alumina at a slower rate and at a faster rate than the rate corresponding to normal consumption within the tank.