METHOD OF MANUFACTURING SILICON USING COAL ASH AS RAW MATERIAL

摘要

PROBLEM TO BE SOLVED: To provide a method of manufacturing high purity silicon using coal ash as a raw material source without necessitating a large quantity of energy.

SOLUTION: The method of manufacturing high purity silicon using coal ash as a raw material comprises treatment processes (a)-(d) mentioned below, that is (a) a process for taking out a produced gas containing silicon fluoride by a chemical reaction treatment in which fluorite (CaF2) is blended with coal ash and concentrated sulfuric acid is dropped thereinto under heating, (b) a process for dehydrating the produced gas to be converted into a silicon fluoride-containing gas, (c) a process for separating a hydrogen fluoride-containing liquid and a silicon fluoride-containing liquid from other component-containing gases by condensing and liquefying the silicon fluoride-containing gas in a cooling process of at least 2 stages which have different cooling temperature from each other and (d) a process for obtaining high purity silicon by evaporating the silicon fluoride-containing liquid separated by the condensation and liquefaction, mixing with gaseous hydrogen and reducing under heating.

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