Numerical modelling of silicon melt purification in induction directional solidification system

Solar grade silicon production is an energy intensive and harmful to the environment process. Yet 40% of this valuable product material is lost into sawdust (kerf loss) during wafering. The kerf waste from Fixed Abrasive Sawing of PV silicon wafers is pelletized and then remelted in an induction fur...

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Published inInternational journal of applied electromagnetics and mechanics Vol. 53; no. 1_suppl; pp. S95 - S102
Main Authors Djambazov, G., Bojarevics, V., Pericleous, K., Forzan, M.
Format Journal Article
LanguageEnglish
Published London, England SAGE Publications 01.01.2017
Sage Publications Ltd
Subjects
Crucible furnaces
Directional solidification
Electromagnetic induction
Flow control
Impurities
Induction coils
Kerf
Mathematical models
Particulates
Sawdust
Sawing
Silicon carbide
Silicon oxides
Temperature control
Three dimensional models
electromagnetic separation
Silicon recycling
dual frequency induction melting
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Summary:Solar grade silicon production is an energy intensive and harmful to the environment process. Yet 40% of this valuable product material is lost into sawdust (kerf loss) during wafering. The kerf waste from Fixed Abrasive Sawing of PV silicon wafers is pelletized and then remelted in an induction furnace. The furnace has a square cross-section quartz crucible, surrounded by graphite susceptors and heated by an induction coil that enables directional solidification of the new ingot. Top and bottom `pancake' coils provide additional temperature control. Once melted, silicon becomes electrically conductive and subject to stirring by induction. To recycle the silicon, particulate impurities (due to the sawing, condensed silicon oxides or carbides) need to be removed. Flow control and the electromagnetic Leenov-Kolin force are used to expel particulates, through a novel dual frequency induction scheme. Three-dimensional, multi-physics numerical modelling captures the electromagnetic, fluid-flow and heat-transfer effects in this process. The presented results show it is possible to retain the impurity particles on the sides of the solidified ingot where they can be sliced off and removed.
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ISSN:1383-5416
1875-8800
DOI:10.3233/JAE-162248