METHOD FOR PREPARING AMORPHOUS SILICON DIOXIDE Russian patent published in 2005 - IPC

FIELD: inorganic chemistry, chemical technology.

SUBSTANCE: invention relates to technology for processing mineral raw. Method for preparing amorphous silicon dioxide involves grinding silicon-containing raw, its treatment with alkaline reagent at 150-170°C, separation of formed precipitate, precipitation of silicon dioxide from prepared liquid phase with mineral acid, isolation of formed silicon dioxide by filtration followed by washing out and drying. The natural mountain rock marshalite is used as the parent silica-containing raw. Grinding silica-containing raw is carried out in centrifuge up to preparing fraction with the dispersity grinding index 10-15 mcm. Ground silica-containing is subjected for alkaline treatment under pressure 4.5-5.5 atm with 8-10% sodium hydroxide solution taken in the ratio liquid : solid = (4.5-5.5):1. Precipitation of silicon dioxide is carried out with 45-50% nitric acid in the ratio liquid : solid = (3-3.5):1 and product obtained after washing out is subjected for additional treatment with 10-12% nitric acid. Invention provides expanding assortment of used raw materials, simplifying technology and enhancing yield of highly dispersed silicon dioxide showing broad range of industrial properties.

EFFECT: improved preparing method.

4 cl, 1 tbl, 3 dwg