Graphite electrode for electrothermic reduction furnaces, electrode column, and method of producing graphite electrodes

Abstract

A graphite electrode for an electrothermic reduction furnace is formed from anode grade coke and graphitized at a graphitization temperature below 2700° C. The resulting electrode is particularly suited for carbothermal reduction of alumina. It has an iron content of about 0.05% by weight, a specific electrical resistivity of above 5 μOhm·m, and a thermal conductivity of less than 150 W/m·K. The graphite electrode is manufactured by first mixing calcined anode coke with a coal-tar pitch binder, and a green electrode is formed from the mixture at a temperature close to the softening point of the pitch binder. The green electrode is then baked to carbonize the pitch binder to solid coke. The resultant carbonized electrode, after further optional processing is then graphitized at a temperature below 2700° C. for a time sufficient to cause the carbon atoms in the carbonized electrode to organize into the crystalline structure of graphite.