Abstract: A lining to support the liquid contents of an aluminium electrolytic reduction cell includes an upper layer which is penetrated by electrolyte during operation of the cell, consisting essentially of unbonded alumina, including a substantially close-packed array of alumina shapes, the gaps between the shapes being substantially filled with particulate alumina in one or more fractions having discrete particle size ranges, including a fraction having an average particle diameter not more than 20% of the average diameter of the shapes, the layer having a bulk density of at least 2.0 g/cc.

Abstract: A cermet material comprises an intergrown network of a minor proportion of ceramic such as TiB.sub.2 in a metal matrix such as Al. The cermet is prepared by forming a minor proportion by weight of a ceramic phase in situ in a molten metal phase and holding the mixture of elevated temperature for a time to effect formation of an intergrown ceramic network.

Abstract: An aluminium reduction cell includes a potlining 16, which may be of alumina, with cathode current collectors 24, 32 embedded therein. The cell floor has an array of depressions 22 with at least one collector at the bottom of each depression. The depressions are filled with metal-wettable bodies 20, e.g. 5-20 mm diameter balls of titanium diboride, sized to prevent the entry of electrolyte or sludge. The depressions may be elongate in a direction perpendicular to the horizontal magnetic field in the cell.

Abstract: An aluminium reduction cell includes an anode 10, electrolyte 12, a cathode 14, a potlining 16 which may be of alumina and cathode current collectors embedded therein. The collectors include a section comprising a major proportion by volume of bodies 22, e.g. of titanium diboride or a TiB.sub.2 /Al cermet, joined or surrounded by aluminium, the section being so positioned that the aluminium is at least partly fluid when the cell is in operation. The bodies, which are preferably close-packed, may be cubic or cuboid or in the form of sheets or thin slabs arranged with their major faces parallel to one another and to the axis of the collector section. The collectors show good electrical conductivity together with satisfactory resistance to magnetic stirring and impact and transverse forces.

Abstract: A method of making a refractory material, e.g. suitable for use in lining Al electrolytic cells, comprises passing molten Al containing suspended particles of a transition metal diboride (e.g. TiB.sub.2) through a refractory filter, on and in which the particles are deposited. The filter can be used as it is, or compressed and sintered, or comminuted and formed into bodies. The concentration of the diboride may be at least 25% on the upstream surface of the filter but progressively reduced with increasing distance from that surface.

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: A shaped refractory article of titanium diboride or other metal has a microstructure with a weight average grain diameter of from 0.5 to 5 microns and substantially no grains larger than 10 microns diameter, from 10% to 45% by volume being made up of interconnected pores the majority having a diameter not substantially greater than 5 microns, porosity and grain size being substantially uniform throughout the microstructure, the article containing not more than about 0.2% by weight of oxygen and not more than about 0.5% by weight of carbon. The article may include inert particulate material in a matrix of the porous metal boride.The article may be formed by forming a uniformly mixed body of reactants into shaped compacts and heating the compacts to cause evolution of carbon monoxide and formation of a coherent reaction sintered product. Numerous reaction schemes are given, but the following are preferred:2TiO.sub.2 +B.sub.4 C+3C.fwdarw.2TiB.sub.2 +4CO (1)TiO.sub.2 +B.sub.2 O.sub.3 +5C.fwdarw.TiB.sub.

Abstract: In an electrolytic reduction cell for the production of a molten metal by electrolysis of a molten electrolyte, the product metal collects on a cathodic carbon floor having embedded steel current collector bars for leading out the cathodic current. In order to reduce the wave motion of the metal due to interaction of horizontal currents in the product metal with the magnetic fields due to currents in conductors associated with the cell, electrically non-conductive barrier members are arranged on the floor of the cell transversely of horizontal currents in the product metal. Such barrier members have at least a surface layer of material resistant to product metal and extend upwardly from the cell floor to a height approximating to the normal maximum operating level of product metal.

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 refining Al or Mg a stream of relatively impure molten metal is passed along one face of a grille separator having interstices of the order of 0.1-1 cm in width. The interstices are filled with a molten salt electrolyte adapted to transport ions of the selected metal (Al or Mg) to a body of refined metal on the opposite side of the separator. The relatively impure metal is made in the anode and the refined metal is the cathode. Refined metal is progressively withdrawn from the cathode. The grille separator may be arranged substantially vertical or substantially horizontal, usually with slight inclination. Passages are preferably provided in the separator to allow escape of gas generated at a metal/electrolyte interface.