Electrolytic production of aluminum using a composite cathode
AssigneeAluminum Company of America
InventorsSubodh K. Das, Perry A. Foster, Jr., Gregory J. Hildeman
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Abstract
A metal such as aluminum is produced by electrolysis of a compound of the metal in a solvent or bath such as molten salt. Electrolysis is carried out by passing a current from an anode to a cathode between which the solvent bath is situated. The cathode is composed of a composite comprising graphite and a refractory hard metal such as titanium diboride. The properties and performance of the composite cathode are improved through careful manufacturing controls and selectivity with respect to electrode configuration and cell operating conditions.
Claims38
A method for the production of metal in an electrolytic cell comprising electrolyzing a bath comprising a compound of the metal dissolved in a molten solvent by passing electric current between one or more anode and one or more cathode surfaces to produce said metal which collects as a molten pool upon a base cathode surface, wherein the improvement comprises providing one or more cathode surfaces extending outwardly from said base cathode surface toward each anode, said cathode surfaces being provided as composite surface regions comprising graphite impregnated with refractory hard metal and by providing a composite mixture comprising carbonaceous binder and refractory hard metal and graphitizing said composite mixture at a temperature of at least 2350.degree. C. in a non-oxidizing atmosphere to convert carbonaceous material therein to the graphitic structure and produce a unitary continuous graphite structure impregnated with refractory hard metal at said cathode surface region.
A method for the production of aluminum in an electrolytic cell comprising electrolyzing a molten fluoroaluminate salt bath containing aluminum oxide dissolved therein by passing electric current between one or more anodic and one or more cathodic surfaces to electrolyze said bath therebetween to produce molten aluminum which collects beneath said salt bath as a molten pool, wherein the improvement comprises providing one or more cathodic surfaces protruding from a base cathode beneath said molten aluminum pool and into said molten aluminum pool, the surface regions of said protruding cathode surfaces being provided as a composite comprising graphite impregnated with a refractory hard metal selected from the group consisting of the borides of titanium and zirconium, and provided by providing a composite mixture containing said refractory hard metal in particulate form and a carbonaceous binder to form a compact, baking to drive off volatiles from said compact without changing its internal structure and thereafter graphitizing said composite to convert carbonaceous material therein into graphite, said graphitization being carried out at temperatures over 2350.degree. C. in a non-oxidizing atmosphere to produce at said cathode surface regions a substantially unitary continuous graphite structure impregnated with refractory hard metal.
Dependencies are inferred from the claim text.