Anodic overvoltage in cryolite-alumina melts

Influence of additives was studied aluminum, potassium and lithium fluorides in the industrial composition of the electrolyte (CR 2.2 and 4 %. CaF 2 ) on the anodic overvoltage while maintaining a constant electrolyte superheat of 15 °С (relative to liquidus). Studies were carried out switching method (method of interrupt current). Polarization dependences were received for the studied electrolyte compositions, described polarizing Tafel equation. The mechanism of the influence of electrolyte composition on the anodic overvoltage was proposed. It is obtained that cryolite ratio (CR) decrease with the 2.2 to 2.1 reduces the anodic overvoltage significantly, introduction of lithium fluoride causes rise it in the industrial range of current densities. Adding in the melt of potassium fluoride reduces the anodic overvoltage significantly.