Refining of Silicon Using an Induction Furnace in the Fractional Melting Process

Abstract

A new fractional melting process using an induction furnace and a centrifugal system has been developed for metallurgical-grade silicon (MG-Si) refining. An induction furnace enables rapid heating and therefore reduces the total refining process time. Impurity-rich liquids can be ejected effectively from the MG-Si by the centrifugal force induced by a motor. The impurity behaviors of the refined samples are observed by scanning electron microscope (SEM). The refining efficiency, which depends on sample size and centrifugal force, is evaluated using inductively coupled plasma atomic emission spectroscopy (ICP-AES) and inductively coupled plasma mass spectroscopy (ICP-MS). The purity of the refined silicon increases with the centrifugal force. The correlation between the centrifugal force and silicon purity is rationalized using the surface tension of impurity-rich liquids. In spite of the rapid heating rate by induction furnace, the MG-Si is refined and 96.7% of the impurities are removed at rotation speeds of 3000 rpm.