Simple and Highly Effective Purification of Metallurgical-Grade Silicon Through Metal-Assisted Chemical Leaching

The present study proposed a simple and highly effective method for removal of impurities from large-sized particle metallurgical-grade silicon (MG-Si) powders based on metal-assisted chemical leaching (MACL). The various leaching approaches (MACL, HF + H₂O₂ leaching, HF leaching, HCl leaching) were investigated for leaching behaviors of the main impurities (Fe, Al, Ca, Ti, Ni, V, Mn, and Cu). The leaching results show that the order of impurities’ removal efficiency, from highest to lowest, is MACL > HF − H₂O₂ leaching > HF leaching > HCl leaching. After MACL, The numerous micro-scale “channels” introduced by MACL which are beneficial for the removal of impurities, especially for the non-dissolving metal impurities, such as copper, calcium, and aluminum. It should be noted that the small amount of Cu mainly come from residual Cu nanoparticle and can be removed by simple acid washing.