Electromagnetic (EM) Purification of Metals

1. Accumulation Induced Current Electromagnetic Force High Frequency Magnetic Field Electromagnetic (EM) Purification of Metals Thermocouple Ar gas inlet Lucas Nana Wiredu Damoah, Department of Materials Science and Engineering Dr. Lifeng Zhang, Department of Materials Science and Engineering Insulation fiber SiO2 crucible 100 µm Top-cut Silicon Induction coil IR Pyrometer Discussion Project Objectives Graphite susceptor Distribution of Particles in Aluminum Insulation brick Quartz tube • High frequency EM field is effective to separate nonmetallic inclusions from metals. • Separation mechanism: induced fluid flow carries particles to the vicinity of the wall where EM Archimedes force traps them. • Higher coil current favors separation efficiency. • Having silicon with already dispersed particles and designing a continuous process are major challenges • Nonmetallic inclusion particles were successfully separated from aluminum and silicon by EM field. • Wall temperature should be lower than the melt in order to separate particles from aluminum. • Higher coil currents enhanced separation efficiency but particle concentration shows no clear effect. • Higher frequency appeared to give higher efficiency probably due to stronger induced fluid flow. • Investigate the particle distribution in Aluminum following high frequency EM field application • Investigate the effect of frequency, current and concentration on inclusions separation from silicon under EM field Background After Before Distribution of Particles in Silicon • Nonmetallic inclusions are detrimental to properties. EM field as a potential technology to effective recycle and refine these important materials. • Parametric studies for EM particles separation from aluminum. • Attempt will be made at a continuous process design. Concluding Remarks Before HSC’s Forecast, 2009 After • Recycling aluminum scraps saves over 90 %, 68 % SoG-Si feedstock is wasted [1]. Separation efficiency from Silicon vs. parameters Approach Nonconductive Particle Liquid Metal Future Work Induction Coil • Thanks to: • DOE Award No. DE-EE0000575 and the Intelligent Systems Center (ISC), Missouri S&T. D. Sarti and R. Einhaus, Silicon feedstock for the multi-crystalline photovoltaic industry.Solar Energy Materials and Solar Cells, 72(1-4): p. 27-40. (2002). • The induced Lorentz force acts on the electrically conductive melt toward the center and the nonmetallic inclusions experience the opposite EM Archimedes force. Acknowledgements References