The influence of mechanical activation on the process of thermal reduction of Silica by Magnesium powder

摘要

Thermal behavior and phase composition of mechanically activated SiO_2-Mg stoichiometric mixtures have been investigated, depending on the time of mixture's preliminary mechanical processing and activation. SiO_2 used in experiments was in the form of aqua silica gel extracted from serpentinites using a new thermo-chemical method of the treatment of serpentinous ultra basic rocks. Different thermal analysis (DTA) and X-ray diffraction (XRD) methods have shown that the displacement reaction in the mixture starts at the range of temperatures 350-400℃ and the products are mainly nanocrystalline magnesium oxide (MgO) and silicon (Si). Along with those main products, a little quantity of nanocrystalline forsterite (Mg_2SiO_4) has been observed at several experiments too. Magnesium oxide and forsterite could be easily removed from the products by decantation and subsequently nanocrystalline Si could be separated and produced. The yield of reaction's products depends on the parameters of mechanical processing. Optimal parameters have been found in order to provide occurring reaction.