The use of rotating-impeller gas injection in aluminum processing

The three major characteristics of liquid aluminum quality are hydrogen content, alkaline content, and inclusion content. The past 20 years have seen considerable development in rotating gas injectors processes, at different steps of liquid metal processing in the casthouses, designed to address these three quality factors. Simultaneously, a great deal of academic work has been done to understand and model these processes, using knowledge from the fields of chemical engineering, thermodynamics, and fluid dynamics. This article shows how very simple efficiency models can be used to represent the processes, combining first-order kinetics for batch treatment and residence time distribution for in-line systems, leading to realistic efficiency laws. These laws are valid for all quality factors under the same form and involve very few parameters.