Boron removal from metallurgical grade silicon by oxidizing refining

A purification process was developed to remove impurity element boron from the metallurgical grade silicon by the electric arc furnace refining. The thermodynamic equilibria calculation and experiment to remove boron in the oxidizing atmosphere were performed and analyzed. Boron is removed as the gaseous species BxOy and BxHzOy in O2 and H2O-O2 atmosphere respectively. The equilibrium pressure of BxHzOy is 105–1010 times that of BxOy. Boron is removed and its content in silicon is reduced from 18× 10−6 to 2×10−6 in the Ar-H2O-O2 atmosphere in the electric arc furnace.