Abstract: In conventional electrolytic cells for aluminium production, heat loss through the side walls is necessary to cause the formation of a protective layer of solid electrolyte. In this invention, the side walls are lined with a ceramic material, e.g. titanium diboride, resistant to the electrolyte and to molten aluminium. Thermal insulation is provided such that a layer of solid electrolyte is not present during normal operation of the cell. A cathode current collection system is provided such that the horizontal lateral currents in the cathode are insignificant compared with the vertical current.

Abstract: In an electrolytic reduction cell for aluminium production, the cathode is constituted by an array of upwardly open tubular elements (5) filled with molten metal and extending upwards from the molten metal pool (8) into the molten electrolyte (9). The metal within each tube is in open communication with the molten metal in the pool. The elements are of a material such as titanium diboride which is wetted by molten aluminium but not by molten electrolyte. The vertical tubes in the elements have an internal diameter, preferably of 0.5-2.5 cms, chosen so that the molten metal level therein is maintained at or close to the top of the tube by capillary action. Preferably the tubular elements extend about 1-4 cms up into the molten electrolyte layer and are positioned at a center-to-center spacing of 1.2 to 3 times their external diameter.