Cell operation and metal purity challenges for the use of inert anodes

Abstract

Inert anodes demand a fairly high alumina content (>50% saturation) in the electrolyte, requiring a new way to control the alumina concentration. Probably the greatest challenge is how to tackle anode corrosion, which gives rise to metal contamination. All candidate oxide materials that can be used as components of inert anodes have a finite solubility in the electrolyte. Consequently, the anode materials will corrode slowly, and the corrosion products will be reduced into the aluminum produced. Even if the anode corrosion rate is slow (10–20 mm/year), an unacceptable contamination of the aluminum may result. Possible ways to reduce the contamination are discussed.