The technology of batch degassing for hydrogen removal from aluminium melts utilising different rotor designs

摘要

Rotary degassing of liquid aluminium alloys is a widely used commercial process to control levels of hydrogen, alkali metals and inclusions in the melt prior to casting. A comprehensive theoretical understanding of the kinetics of aluminium degassing has been established in the past twenty years. Whilst there have been some published experimental tests of degassing theory in molten aluminium, in many cases key pieces of information are not reported or determined, such that a critical assessment of the underlying theory is compromised. Similarly, practical implementation of such understanding in usable shop-floor process models has met with difficulties owing to lack of knowledge concerning some key parameters. These include the stirring intensity dissipated in the melt, and its relationship to the average gas bubble size, and the mass transfer coefficient at the free surface of the melt.