METHOD FOR PRODUCING SYNTHETIC SILICON DIOXIDE

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The invention relates to a method for producing synthetic silicon dioxide (SiO2) from ash formed as a result of combustion of organic fuel (black coal or brown coal, peat, lignites, oil shale, timber, or animal, poultry or agricultural waste) containing SiO2, Al2O3, Fe2O3, K2O, CaO, MgO, rare and rare earth elements. A method is proposed for producing synthetic silicon dioxide, which involves mixing a silicon-containing material with ammonium fluoride; heating the mixture; holding it in a heated state until fluorination is completed; dissolution in water; interaction of the produced solution with ammonia water to form a precipitate of synthetic SiO2, which can be separated by filtering. A distinguishing feature of the proposed method is the fact that after fluorination, the temperature of the mixture is increased to +290-300 °С , it is held for a period of 35-45 minutes, and the mixture is then leached with water at a temperature of +20-100 °С.