Swiss Aluminium Ltd.

Hanspeter Alder

Gerhard Zhuber-Okrog

Hans Boving

Hans P Mueller

Hans Wolfhart Rieger

Ernst Kowolik

Eugen Schalch

The durability of oxide-ceramic anodes can be increased, if the aluminum surface which lies opposite the active anode surface and is in direct contact with the molten electrolyte, is smaller than the active anode surface. The separated aluminum is collected on the floor of the carbon lining and is sub-divided by an insulating material into pools, which are connected together by means of tubes or channels. The total of all the aluminum surfaces exposed to the melt amounts to 10-90% of the active anode surface.

Electrode arrangement in a cell for manufacture of aluminum from molten

The invention relates to an anode of a fusion electrolysis furnace for the production of aluminum, which anode consists of a plurality of individual oxide-ceramic elements of stable dimensions. The individual elements have linear cross-sectional dimensions of 2-12 cm. on the current exit surface. These elements have a length which corresponds to 2-20 times the value of the mean linear cross-sectional dimension, they are arranged approximately parallel with a mean distance between outer surfaces of 1-20 mm. and are held together mechanically stably at the end facing the current entry with an electrically conductive device situated outside the molten electrolyte. The anode in bundle configuration, in comparison with oxide-ceramic anodes of large format, has a lower corrosion erosion, is simpler to produce ceramically and has a greater stability to temperature changes.

Anode of dimensionally stable oxide-ceramic individual elements

A device for producing solid aluminum chloride from gas containing gaseous aluminum chloride by means of a fluidized bed condenser. Between the inlet pipe for carrier gas and an outlet pipe for residual or waste gas there is a distributor plate with openings in the form of nozzles, at least one cooling facility, a feeding facility for the supply of gas containing gaseous aluminum chloride and a facility for drawing off the solid aluminum chloride. The outlet pipe for waste or residual gas is connected to the inlet pipe for carrier gas via a separator which separates out fine particulate aluminum chloride, which is then fed back to the bed to act as nuclei.

Device for the production of solid aluminum chloride

The efficiency of a given reactor for the conversion of aluminum oxide bearing starting material by means of reducing and chlorinating gases or of carbon coated aluminum oxide bearing starting material by means of chlorinating gases in a solid/gas fluidized bed to yield aluminum chloride is improved by the addition of an inert, solid dilution agent to the bed. Whereas, as a result of the chemical reaction, the average particle size and bulk density of the reagent decreases in a batch process, and in a continuous process an equilibrium value is reached, the average particle size and the bulk density of the inert material remains unchanged. An initial average particle size of 60-80 microns proved successful; quartz, corundum, magnesium oxide of similar particle size and bulk density was added as dilution agent, and a gas flow rate of 2 to 30 cm/sec was attained along with quantitative conversion of the gaseous reagent. The increase in the space-time-yield of a fluidized bed reactor, measured by the conversion achieved before onset of breakthrough in the fluidized bed, amounted to 58 to 65%.

Process for the production of aluminum chloride

The minute pores and discontinuities which are normally present in protective oxide coatings on carbon bodies can be closed and, if desired, filled by immersing the coated carbon body in a metal salt melt having a boiling point above 400.degree. C., and electrodepositing the melt on the coated carbon body. When the electrodeposition step is continued sufficiently long to fill the pores, the product when cool is a coated carbon body carrying an oxidation agent-resistant coating which is keyed into the surface of the carbon.

Oxygen-resistant electroconductive carbon bodies

A molten salt charge as used in the electrolysis of aluminum contains aluminum oxide in excess of the eutectic composition and is cooled at a surface colder than the melt in such a way that the aluminum oxide precipitates onto this surface in the form of corundum crystals. Such a layer of crystals provides chemical and electrical insulation to the cooling surface under the corrosive conditions produced by the charge.

Refractory article for electrolysis with a protective coating made of

A process for the continuous measurement of the electrolyte parameters during the electrolysis of metallic compounds in particular aluminium oxide, dissolved in a melt. A measuring current of current density of at least 0.01 A/cm.sup.2 with respect to the anodic measuring surface, is passed through an anodically polarized measuring probe which has a measuring surface whch is wet by the corrosive electrolyte and which is made of an inconsumable ceramic oxide material.

Continuous measurement of electrolyte parameters in a cell for the

Process for operating a cell for the electrolysis of a molten charge, in particular aluminum oxide, with one or more anodes the working surfaces of which are of ceramic oxide material, and anode for carrying out the process. In the process a current density above a minimum value is maintained over the whole anode surface which comes into contact with the molten electrolyte. An anode for carrying out the process is provided at least in the region of the interface between electrolyte and surrounding atmosphere, the three phase zone, with a protective ring of electrically insulating material which is resistant to attack by the electrolyte. The anode may be fitted with a current distributor for attaining a better current distribution.

Inconsumable electrodes

Protective material made of corundum crystals

A process for the electrolysis of a molten charge in particular of aluminum oxide, in a cell which is fitted with one or more anodes whose working surfaces are of ceramic oxide material. The parts of the anode surface which are not protected from corrosive attack by means of a sufficiently high current density are subjected to a stream of oxidizing gas.

Process for the electrolysis of a molten charge using inconsumable anodes

Process for operating a cell for the electrolysis of a molten charge, in particular aluminum oxide, with one or more anodes, the working surfaces of which are of ceramic oxide material, and anode for carrying out the process. In the process a current density above a minimum value is maintained over the whole anode surface which comes into contact with the molten electrolyte. An anode for carrying out the process is provided at least in the region of the interface between electrolyte and surrounding atmosphere, the three phase zone, with a protective ring of electrically insulating material which is resistant to attack by the electrolyte. The anode may be fitted with a current distributor for attaining a better current distribution.

Electrolysis of a molten charge using incomsumable electrodes

A process for the production of metals by the electrolysis of metal compounds dissolved in a molten electrolyte, in particular for the production of aluminum from aluminum oxide. The electric power is passed through a multi-cell furnace with at least one inconsumable bi-polar electrode, made of electrode materials which are compatible with one another. The anions, in particular, the oxygen ions of the dissolved metal compounds have their charges removed on the surface of the electron conductive ceramic oxide anode and the metal ions, in particular the aluminum ions on the surface of the cathode which is made of another material than that used for the anode surface.

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Flurlingen, Switzerland

Hanspeter Alder