Open Access

ARTICLE

Comparison Between the Influence of Mechanical and Electromagnetic Stirring on Aluminum Ingot Purity During Ohno Continuous Casting

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1 Department of Materials Science and Technology, Harare Institute of Technology, Harare, Zimbabwe.
2 Department of Physics, Abdul Wali Khan University, Mardan, 23200 KPK Pakistan.
* Corresponding author: Tel./fax: +263-4-741430, E-mail address: sfashu04@gmail.com

Fluid Dynamics & Materials Processing 2016, 12(4), 173-192. https://doi.org/10.3970/fdmp.2016.012.173

Abstract

This paper outlines the findings in the comparison of the influence of mechanical and electromagnetic stirring on ingot long term purity and uniformity during Ohno Continuous Casting. 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 electromagnetic stirring were obtained by numerically solving the solidification model coupled with either the multi-reference frame model (for mechanical stirring) or the magnetohydrodynamic model (for electromagnetic stirring) in CFD Fluent 6.3.26 software. For mechanical stirring, an optimum stirring intensity of 2mm/min was determined whilst for electromagnetic stirring, the optimum magnetic field with an amplitude of 20mT and a frequency of 2.7Hz was determined and these produced same magnitude optimum flow fields resulting in high purity aluminum ingots. Comparison of the two methods showed that electromagnetic stirring is good in covering all the regions near the solid-liquid interface and is more effective in bulk melt mixing; thus produces more uniform and purer ingots for longer casting times.

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