LAUSR

The present work aims at investigating the impact of thermal pretreatment and acid leaching (HCl–HF) on the boron removal efficiency of metallurgical grade silicon (MG-Si). The impact of various parameters, involving oxidation temperature (700–1200 °C), oxidation time (1–5 h) and acid leaching (4 mol L−1 HCl–3 mol L−1 HF), on the removal of boron from MG-Si was thoroughly explored. It was found that thermal oxidation resulted in an enhanced removal efficiency of boron from MG-Si. By employing MG-Si particles in the range of 75–106 μm in conjunction with acid leaching at 65 °C for 6 h, the boron content was decreased from 19.60 to 14.10 ppmw, offering a removal efficiency of ca. 28%. When the MG-Si powder was subjected to thermal oxidation at 1100 °C for 5 h before leaching, the boron concentration in the purified Si was reduced from 19.60 to 8.90 ppmw, giving an extraction efficiency of 54.59%. An extended characterization study, regarding the microstructure, morphology and chemical composition of both un-treated and treated samples, was conducted to gain insight into the underlying mechanism of boron removal under different conditions.