Hydrometallurgical Purification of Magnesium-Doped Silicon by Different Acids

The purification of commercial metallurgical grade silicon through alloying and then acid leaching is studied. Magnesium is added into molten silicon and then acid leaching of the solidified Si-Mg alloy by HCl, H2SO4 and HNO3 acids is done. The main parameters that are studied are acid concentration on leaching of particles with a specific size range. Chemical analysis of the samples before and dafter leaching are determined by high resolution Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS). It is shown that the impurity removal from silicon is depending on the type of acid. Moreover, the applied method is efficient for the removal of particular impurities such as P, Fe, Ti, Al, Ca, …. In addition, it is indicated that HCl is more effective than the other types of acids for given process conditions. Moreover, the best silicon purification, and in particular P removal is obtained when HCl with 10% and 15% concentrations is used.