METHOD OF PREPARING FINE HIGH-POROUS SILICA Russian patent published in 2004 - IPC

FIELD: inorganic compounds technology.

SUBSTANCE: fine precipitated silica with great pore volume, high moisture and oil capacity, useful as filler for various materials is prepared as follows. Sodium or potassium silicate with 3 to 35 wt % SiO₂ equivalent is added to 5-40% ammonium sulfate, carbonate, bicarbonate, chloride, nitrate, format, or acetate solution, ratio of total amount of SiO₂ added with silicate to amount of ammonium salt being not higher than 2. Silica hydrogel precipitates at 35-95^оС is subjected to additional treatment with 5-15% solution of above-defined ammonium salt to form fine high-porous silica. Precipitation rate is chosen above 300 g SiO₂ in 1 l of suspension during 1 h in order to eliminate zones of local supersaturation of reaction mixture when sodium silicate is added to reaction zone.

EFFECT: reduced loose density and increased moisture and oil capacity.

3 cl, 1 tbl