ALUMINIUM FLOTATION IN STIRRED REACTOR: A MATHEMATICAL MODEL AND A COMPUTER SIMULATION COUPLING CFD AND POPULATION BALANCE

摘要

Removing inclusions from molten aluminium by flotation in stirred reactors is widely used in liquid aluminium treatments. This process consists of gas injection into the liquid bulk using an impeller: inclusions are attached to the bubbles during their ascension in the liquid bulk and are released in the dross layer. With the aim both of a better understanding of the physical phenomena acting during flotation and of the optimization of the refining process, a mathematical model of the behaviour of the inclusions population has been built up. Transport phenomena, agglomeration of inclusions, sedimentation and flotation are investigated and modelled. The simulation couples Population Balance with convective transport of the inclusions, in the diphasic flow field, in order to predict the evolution of the size distribution of inclusions as a function of time. A laboratory scaled flotation vessel has been modelled and results of a 2D simulation are presented.