METHOD OF PRODUCING SYNTHETIC SILICON DIOXIDE Russian patent published in 2016 - IPC C01B33/18 

FIELD: chemistry.

SUBSTANCE: invention relates to production of synthetic silicon dioxide (SiO₂) of ash from burning organic fuel (black or brown coal, peat, lignite, combustible shale, wood, wastes from livestock sector, poultry farming, agriculture), containing SiO₂, Al₂O₃, Fe₂O₃, K₂O, CaO, MgO, rare and rare-earth elements. Method involves mixing ashes with ammonium fluoride, heating mixture, holding in a heated condition before fluorination with formation of ammonium hexafluorosilicate, raising temperature of mixture to 290-300 °C, holding for 35-45 minutes, leaching with water at temperature +20-100 °C, dissolving in water and reacting obtained solution with ammonia water for precipitation of synthetic SiO₂, separated by filtration. Mixing ashes with ammonium fluoride is primarily performed by mechanical activation.

EFFECT: technical result consists in reduction of duration of step of separating ammonium hexafluorosilicate from mixture, use of low temperatures, low cost of equipment and power consumption.

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