US Patent 7455822 Method for production of silicon

A process for production of Si, characterized by adding an oxide, hydroxide, carbonate or fluoride of an alkali metal element, or an oxide, hydroxide, carbonate or fluoride of an alkaline earth metal element, or two or more of such compounds, to solid SiO in a total molar amount of from 1/20 to 1000 times with respect to the moles of solid SiO, heating the mixture at between the melting point of Si and 2000° C. to induce a chemical reaction which produces Si and separating and recovering the Si from the reaction by-product, for the purpose of inexpensively and efficiently producing Si from various forms of solid SiO with no industrial value produced from Si production steps and the like.