Abstract: A composite material comprises a body, e.g., a slab, of a fused refractory oxycompound (3) having a multiplicity of discrete inclusions such as lumps (1) of an aluminum-wettable RHM in its surface. These bodies are especially useful as aluminum-wettable but non-current carrying components of aluminum reduction cells.

Abstract: A cell for the electrowinning of aluminum from molten salts has a cell bottom lining consisting partly of a refractory mass (4 ) and partly of carbon bodies (5). At least 30% and preferably 50% or more of the cell bottom area is occupied by the refractory mass (4). The carbon bodies (5) are level with the refractory mass (4) or are recessed therein.

Abstract: A cell for the electrowinning of aluminum from molten salts has a cell bottom lining consisting partly of a refractory mass (4) and partly of carbon bodies (5). At least 30% and preferably 50% or more of the cell bottom area is occupied by the refractory mass (4). The carbon bodies (5) are level with the refractory mass (4) or are recessed therein.

Abstract: An aluminum production cell with a non-conductive cell bottom composed predominantly of alumina (1) has a plurality of vertical current collector plates or posts (3), e.g., of steel protected at their upper ends by a carbon body (4), e.g., a plate, slab or cap which contacts the cathodic pool of molten aluminum (10).

Abstract: A bipolar electrode for electrowinning aluminum or other metals by electrolysis of a molten salt electrolyte containing a dissolved compound of the metal to be won comprises an anodic and a cathodic surface which are both preserved during operation by dissolution of small amounts of a substance in the electrolyte which is capable of being deposited on either surface at a rate compensating the corrosion thereof during electrolysis. The anodic surface is for example cerium oxyfluoride and the cathodic surface cerium hexaboride, both surfaces being preserved by addition of cerium compounds, such as oxides, fluorides, hydrides etc. to the melt. The cathodic surface may also include titanium diboride on top of or together with cerium hexaboride.

Abstract: A composite material comprises a body, e.g., a slab, of a fused refractory oxycompound (3) having a multiplicity of discrete inclusions such as lumps (1) of an aluminum-wettable RHM in its surface. These bodies are especially useful as aluminum-wettable but non-current carrying components of aluminum reduction cells.

Abstract: The present invention provides a ceramic/metal composite material comprising cerium/aluminum mixed oxides as the ceramic phase and an alloy or intermetallic compond of cerium and at least one of aluminum, nickel, iron and cobalt as the metal phase. The ceramic phase may comprise interengaged crystal lattices of ceria and alumina. The material may be a self-sustaining body which may be used as substrate for a dimensionally stable anode in molten sale aluminum electrowinning cells, coated with a protective layer of cerium oxyfluoride in situ during electrolysis in molten cryolite containing cerium ions.

Abstract: A method of producing aluminum by electrolysis of alumina dissolved in molten cryolite at temperature between 680.degree.-690.degree. C. is disclosed. The method comprises the employment of permanent anodes the total surface of which is increased up to 5 times compared to the total surface of anodes in a classical Hall-Heroult cell of comparable production rate. By this means the anodic current density is lowered to a degree which permits the discharge of oxide ions preferentially to fluoride ions at an acceptable rate. Additionally, the electrolyte is circulated by suitable means whereby it passes from an enrichment zone where it is saturated with alumina to an electrolysis zone and back.

Abstract: A method of producing aluminum by electrolysis of alumina which is dissolved in a molten cryolite bath is described which uses a dimensionally stable anode comprising a substrate composed of a conductive ceramic, a cermet, a metal, an alloy, an intermetallic compound and/or carbon and a coating thereon comprising a rare earth metal oxide or a rare earth metal oxyfluoride which is preserved by maintaining a concentration of the rare earth metal in the electrolyte. By adding to the bath a contamination inhibiting agent the contamination of the aluminum by substrate components due to corrosion of the substrate by the electrolyte contacting the substrate at imperfections of the coating may be inhibited. The contamination inhibiting agent may be a compound of an alkali or an alkaline earth metal, such as a fluoride, in particular LiF or MgF.sub.2.