Removal of aluminum from metallurgical grade silicon using electron beam melting

Small amounts of metallurgical grade silicon were melted in an electron beam furnace in different experimental conditions in order to investigate the aluminum (Al) evaporation behavior during the electron beam melting (EBM) process. Impurity was significantly decreased in the early periods of melting at 9, 15, and 21 kW. These changes slowed down with the extension of the melting time. Moreover, the removal reaction of Al by evaporation from molten silicon during the EBM process occurred in accordance with the first order kinetics. The calculated mass transfer coefficients of Al at 1941, 1964, and 2051 K increased with the increase of melting temperature. The removal rate of Al was controlled by the transportation of Al from the bulk of silicon metal to the molten/vacuum interface within the range of the experimental temperature.

► Discussed the kinetic behavior of Al evaporation from molten silicon during EBM process.
► Calculated the evaporation coefficient of Al at different temperature.
► Used three kinds of mass transfer coefficients to judge the rate-controlling step of Al evaporation from molten silicon.