High Efficient Impeller for Rotary Gas Injection in Aluminum Melt

In rotary gas injection (RGI), which is widely used in aluminum industry, impurities are removed by reaction with halide-containing chemicals injected into the melt. However, the constantly increasing concern on environmental protection obliges aluminum makers to eliminate or significantly reduce their usage. In this study, aiming at enhancing the efficiency of chlorine gas treatment for impurities removal from the melt, we investigated the effect of impeller design on the impurity mass transfer by performing physical model experiments on CO 2 absorption, particle image velocimetry (PIV) measurements and numerical simulation. It is shown that a newly designed impeller intensifies the discharged flow as compared to the conventional impeller case that forces the formed bubbles to move to the fragmentation zone near the impeller blade tip. This results in an enhancement of the mass transfer. From the numerical results, it was found that these phenomena could be explained by the trailing vortex structure near the impeller blades.