The mechanism of boron removal in the CaO–SiO2–Al2O3 slag system for SoG-Si

The dissolution behavior of boron in a molten slag was evaluated at 1773 K to establish the boron removal mechanism from silicon refining for preparing higher purity solar-grade silicon. From the experimental results, a mechanism of boron removal from silicon into the CaO–SiO2–Al2O3 slag system was confirmed to proceed via BO33− and B62− following a linear relationship with oxygen partial pressure in the slag system. In addition, the distribution ratio of boron was seen to increase with increasing slag basicity.