ABSTRACT
This article outlines the findings in the comparison of the influence of mechanical and electromagnetic stirring (EMS) on ingot long-term purity and uniformity during Ohno continuous casting (OCC). The magnitude of the average optimum velocity flow field and stirring parameters required to effectively purify aluminum ingots using mechanical stirring of the melt was determined and analyzed. Basing on the determined optimum mechanical flow field, electromagnetic parameters producing almost the same flow field near the interface were obtained through careful adjustments of parameters. Optimum parameters of the mechanical and EMS were obtained by numerically solving the solidification model coupled with either the multi-reference frame model (for mechanical stirring) or the magnetohydrodynamic model (for EMS) in CFD Fluent 6.3.26 software. For mechanical stirring, an optimum stirring intensity of 2 mm/min was determined whilst for EMS, the optimum magnetic field with an amplitude of 20 mT and a frequency of 2.7 Hz was determined, and these produced same magnitude optimum flow fields resulting in high-purity aluminum ingots. Comparison of the two methods showed that EMS is good in covering all the regions near the solid–liquid interface and is more effective in bulk melt mixing; thus it produces more uniform and purer ingots for longer casting times.
