ALUMINIUM EXTRACTION.

The Hall-Heroult process is likely to be the dominant method of aluminum production for the remainder of the century. The characteristics of the operation of a modern smelter are described and attention drawn to their disabilities which are due chiefly to the small production capacity of individual cells. The principal components of the Hall-Heroult cell - the electrolyte, the anode and the cathode - are discussed in order to identify the problems of scale-up. The factors influencing current efficiency and energy consumption are analyzed and lead to the conclusion that the greatest potential for energy saving lies in reducing the anode to cathode distance (ACD). The most promising direction for major change is in the application of a new titanium diboride-carbon composite for coating of the surface of the cathode carbon. It improves the wetting of the carbon by aluminum and should permit the use of sloping cathodes and anodes. The deep metal pad would thereby be eliminated and, in the absence of magnetic perturbations, the ACD could be decreased.