Institute of Geology and Nature Management of Far Eastern Department of Russian Academy of Sciences, Blagoveshchensk, Russia:

Demyanova L. P., Senior Researcher, Candidate of Engineering Sciences, e-mail: larisa-demyanova@ascnet.ru

Rimkevich V. S., Head of Department, Candidate of Geological and Mineralogical Sciences

Silica-based raw materials have high potentiality for preparing amorphous silica. The analysis of practically all geologicallygenerated types of quartz which are present on the territory of Russian Federation are investigated, including non-conventional sources. Experiments are carried out on an example of quartz sand which is obtained after enrichment from quartz-kaolinfeldspath raw minerals of the Chalgansky site (Amur region). The elaboration of pure amorphous silica is carried out by the fluoride technology, with the use of a fluorinating reagent: ammonium hydrodifluoride (NH₄НF₂). The purification of impurities of quartz sand is carried out through the formation of an intermediate product, that is ammonium hexafluorosilicate ((NH₄)₂SiF₆), which is then subjected to hydrolysis and finally yields pure SiO₂ and the regeneration of the fluorinating component.

According to the spectral analysis, the content of impurities in amorphous silica does not exceed 10–4 weight %. Also the electrolysis of aqueous solution of (NH₄)₂SiF₆ allows to get amorphous silicon.

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