Abstract: Aluminum contaminated with at least one of the metals of the groups II b, III a, IV a and V a of the periodic table of elements is purified by means of sodium applied in liquid extraction in a separating column in the temperature range between the melting point of the aluminum or aluminum alloys and the boiling point of sodium. The pre-heated sodium is introduced into the separating column from a circuit having a heat exchanger, solids precipitator, pump and storage tank, in quantities at least 5 times greater than the mass of contaminating metal. The sodium flows countercurrent to the contaminated aluminum which is also introduced into the separating column. The purified aluminum containing a small residual amount of contaminating metal and a sodium content not exceeding 500 ppm is removed from the separating column. The sodium containing a low concentration of contaminating metal is returned to the circuit.

Abstract: The solid cathode comprises essentially a supporting element and, at least in the region of the cathode workface, an open-pore structure which is impregnated with or soaked in aluminum saturated with at least one of the transition metals from groups IV B, V B, and VI B of the periodic table of elements, This open-pore structure can be fed continuously from reserves of aluminide/aluminides. An open-pore structure which has shown itself to be particularly advantageous is one comprised of a carbon fiber felt pad a few millimeters thick. The solid cathodes are economical and can be made from material which is readily made into a variety of shapes.

Abstract: The mold features on its work face a thermally insulating protective layer of sub-micron metal oxide particles.The coating can be applied by spraying an aqueous sol of a metal oxide onto the mold work face which has been heated to at least 60.degree. C.The use of sub-micron sized metal oxide particles enables the formation of a protective coating of very low density and consequently very low thermal conductivity. The coating can furthermore be deposited very economically, and likewise removed again.

Abstract: An exchangeable, wettable solid cathode for a fused salt electrolytic cell for the production of aluminum is made out of at least one aluminide of the groups IV A, V A or VI A of the periodic system of elements. A titanium aluminide of the .gamma.-phase has been shown to be particularly favorable for this purpose.

Abstract: A solid cathode in a fused salt electrolytic cell for the production of aluminum is made up of individually exchangeable elements (10). These cathode elements are made up of two parts which are rigidly joined together and which are resistant to thermal shock. The upper part (12) which projects from the molten electrolyte (30) into the precipitated aluminum (26), or the coating on this part (12), is made of a material which, at working temperature, is a good electrical conductor, is chemically resistant and is wet by aluminum. The lower part (14,16), which is exclusively in the liquid aluminum (26), or the coating on this part (14,16) is on the other hand made of an insulating material which can withstand molten aluminum.

Abstract: A wettable cathode for an electrolytic cell for the electrolysis of a molten charge, in particular for the production of aluminum, where the said cathode comprises individual, exchangeable elements each with a component part for the supply of electrical power. The elements are connected electrically, via a supporting element, by molten metal which has separated out in the process. The interpolar distance between the anodes and the vertically movable cathode elements is at most 2 cm.

Abstract: A method of reshaping magnetically relatively weak ferrite particles of substantially arbitrary shape into substantially spherically-shaped globules including the steps of transporting the particles by a carrier gas stream within a conduit into the vicinity of a stream of warm gases, separating the particles from the carrier gas stream prior to contact with said warm gas stream, feeding the separated particles into the stream of warm gases, melting the particles therein, and subsequently allowing the particles to solidify into substantially spherically-shaped globules.

Abstract: A crucible, for use in heating and/or retaining melts at elevated temperatures, includes a hollow holding member composed of a heat resistant material, and a thin-walled insert composed of a substance chemically resistant to oxygen and oxidizing substances and being removably supported in the holding member.

Abstract: A conductor rail includes a load-bearing body of aluminum or an aluminum alloy, and a layer of steel metallically united to the body on the part of the rail to which electrical contact is to be made during use thereof, the steel layer conductively contacting the body.

Abstract: A method of applying to an anode for use in fusion electrolysis a coating for protection of the anode against surrounding influences, comprising delivering the material of the coating in finely dispersed form onto the anode with sufficient heat content and impact energy to cause adhesion between the material and the surface of the anode and consolidation of the material. Preferably the material is applied by means of a plasma burner and, for an anode to be used for the electrolytic production of aluminium, includes aluminium oxide and facultatively aluminium, the thickness of the coating beeing about 0.1 to 1.0 mm.