Boron removal from molten silicon using sodium-based slags

Slag refining, as an important option for boron removal to produce solar grade silicon (SOG-Si) from metallurgical grade silicon (MG-Si), has attracted increasing attention. In this paper, Na2CO3-SiO2 systems were chosen as the sodium-based refining slag materials for boron removal from molten silicon. Furthermore, the effect of Al2O3 addition for boron removal was studied in detail, which showed that an appropriate amount of Al2O3 can help retention of the basicity of the slags, hence improving the boron removal rate.