Process for the electrolytic deposition of aluminum using a composite

Abstract

A process for the electrolytic deposition of aluminum at low temperatures and low electrical potential in which the anode is the sole source of aluminum and comprises a composite mixture of an aluminous material such as aluminum oxide and a reducing agent. The composite anode is positioned in the electrolyte with at least one active surface of the anode in opposed relationship to but spaced from the surface of the cathode. The greatly increased electrical resistance of the mixture of aluminum oxide and the reducing agent is minimized by passing the anodic current through one or more conductors of low electrical resistivity which extend through the mixture to or approximately to the active reaction face of the mixture in the electrolyte. The position of the ends of said conductors is maintained relative to the reaction face as the mixture is consumed in the electrolysis. These arrangements provide a minimal length of current path through the high resistant mixture and thus result in a low voltage drop of anodic current in its passage to the reaction face. A bipolar electrode arrangement may be employed with the mixture of aluminum oxide and reducing agent covering one face of the electrode with the opposite face of the electrode providing a cathode surface.