Purification of metallurgical grade silicon in an electron beam melting furnace

Purifying of metallurgical grade silicon through electron beam melting is a method used to provide high-purity material. In this research, the influence of refining temperature, refining time, electron beam power and feed rate on refining effectiveness are studied. With the improvement of refining temperature, saturated vapor pressure of each impurity element increase quickly, but at the same time the evaporation of the silicon increase. Refining temperature is 2773 K in order to improve the removal of the impurity. In order to make the impurity content decrease by one order of magnitude, the refining time should be 3 h. Through the calculation of electron beam energy, the relationship between melting temperature, electron beam melting power and refining time is calculated. According to the fitting equation of feed rate, silicon ingot coefficient and refining time, feed rate can be calculated from processing parameters. In this research, impurities can be removed effectively through electron beam melting and twice directional solidification. Most industrial silicon impurities can be removed below 10 ppmw, and the concentration of some impurities are even lower than 1 ppmw.

► Electron beam melting is a method used to provide high-purity material. ► Refining parameters are refining temperature, refining time, electron beam power and feed rate. ► Most impurities can be removed below 10 ppmw, some are even lower than 1 ppmw.