Aluminum Fluxing Salts: a Critical Review of the Chemistry and Structures of Alkali Aluminum Halides

摘要

The publication reviews the structural characteristics of crystalline phases and phase equilibria data for the system NaCl-KCl-AlCl3-NaF-KF-AlF3, which encompasses a large number of molten salt fluxes currently used in aluminum recycling. Its purpose is to provide guidelines for research into the relationships between molten salt compositions and their physical properties, notably vapor pressures, densities, surface tensions, and viscosities, knowledge of which is essential to minimizing fluxing efficiencies and metal recovery and minimizing hazardous emissions and disposal problems. In addition, the report describes experimental determinations of sub solidus compatibility relationships in the system, which is of the quaternary reciprocal type, containing 12 different stable 4-phase assemblages in the solid state. The compatibility diagram serves to define the important compositional planes across which important changes in properties are likely to occur.