Alcan International Limited

Douglas N Reesor

Adam J Gesing

Ernest W Dewing

David N Mitchell

Douglas J Wheeler

Peter Alexander Wales

Joseph K Walker

Donald L De Respiris

In an aluminium reduction cell including a cell lining and embedded therein at least one cathode current collector including a high temperature section comprising an electrically conducting refractory material such as titanium diboride, generally in conjunction with molten aluminium metal, corrosion is a problem. The invention provides a substance to protect the collector section. The substance may be a liquid impermeable layer e.g. particulate material impregnated with a molten fluoride-or chloride-containing salt mixture; for a getter such as particulate aluminium to react chemically with gaseous corrosive species. Combinations of these substances may be used, optionally in conjunction with a solid layer such as an alumina or aluminium metal tube.

Aluminium reduction cell

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.

Linings for aluminium reduction cells

A method of purifying aluminum contaminated with cerium or other rare earth metal comprises bringing the molten metal into contact with a halogenating agent. Preferred halogenating agents are aluminum fluoride for reducing cerium levels to around 0.1% to 0.3%, and chlorine gas for reducing cerium levels still further, and these may advantageously be used in sequence. Particulate aluminum fluoride may be introduced into the vortex of a stirred body of the molten metal. The controlled addition of chlorine may be effected by bubbling a mixture of chlorine and an inert gas into a body of the molten metal. The cerium contamination may arise from the use of a dimensionally stable anode comprising cerium dioxide in an aluminum reduction cell.

Method of producing aluminum

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Kingston, Canada

Douglas N Reesor