Numerical simulation for parameter optimization of silicon purification by electron beam melting

In this paper a mathematical model is developed to investigate the removal of volatile impurities in molten silicon by electron beam melting (EBM) with a high efficiency and low energy consumption. The temperature distribution of molten silicon is obtained using the commercial software FLUENT. Based on the temperature distribution, the vaporization behaviors of phosphorus and silicon are investigated by Langmiur's vaporization theory. The results show that the evaporation rate of silicon during EBM increases exponentially with the increase of beam power, while, it decreases with the increase of scanning radius. The optimal parameters are discussed from the aspect of efficiency and energy saving. The energy consumption decreases with the decrease of scanning radius and with the increase of the beam power. The optimum values are consider to be with a scanning radius of 0.0339 m and a beam power of 23.4 kW for 0.5 kg silicon when phosphorus is removed from 1.44 × 10−2 to 1 × 10−5 (wt.%).

► A model is developed for energy utilization optimization during Si purification by EBM.
► The surface temperature and area of the molten pool are calculated.
► The vaporization behaviors of Si and P are discussed.
► The relationship between energy consumption and melting parameters is obtained.
► The melting parameters are optimized from the aspect of efficiency and energy saving.