Properties of fluxes used in molten aluminium processing

Abstract

Molten salt fluxes play an important role in the processing of molten aluminum. Most salt fluxes are based on either the KCl-NaCl or the KCl-MgCl2 binary systems. Additives include other chlorides, fluorides, nitrates, carbonates or sulphates. They are used either in a passive role to cover the metal from oxidation or sometimes in an active role to remove inclusions, alkali metals and magnesium. Salt fluxes can also be used to imporve metal recovery from drosses as well as during melting of recycled scrap. The physical and chemical properties of these various molten salts are reviewed and analysed in terms of applications to the aluminum industry.