Affiliations: [a] University of Greenwich, Park Row, London, UK | [b] Universita degli Studi di Padova, Padua, Italy
Correspondence:
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Corresponding author: G. Djambazov, University of Greenwich, Park Row, London, SE10 9LS, UK. Tel.: +44 2083319589; Fax: +44 2083318925; E-mail:dg12@gre.ac
Abstract: 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.
Keywords: Silicon recycling, electromagnetic separation, dual frequency induction melting
