METHOD OF OBTAINING FINELY-DISPERSE AMORPHOUS MICROSILICA Russian patent published in 2014 - IPC C01B33/18 C09C1/28 

FIELD: chemistry.

SUBSTANCE: method includes preliminary crushing and pounding in an agate mortar of dried and calcined in the muffle furnace diatomite with weight 5-8 g to the powder state, pounding in a porcelain mortar of 6-fold quantity of alkali flux, consisting of a mixture of water-free potassium and sodium carbonates, mixing diatomite and alkali flux in an alundum or corundum crucible, fusion of the obtained mixture in the muffle furnace in the crucible for 40-50 min with further pouring of the melt onto a silicate base, its transfer into a heat-resistant cup, separation of silicic acid first by leaching the melt with distilled water, and then, after carrying out pH control by titration with a 0.1 M solution of potassium hydroxide with methyl orange, its processing with 100-200 ml of distilled water to complete dehydration of silicic acid. Precipitation of silicic acid is carried out by an addition of 30-40 ml of a concentrated solution of hydrochloric acid and after the reaction slowing the solution is evaporated on a sand bath until carbon dioxide release stops. The sediment processing is carried out by addition of 10-20 ml doses of the concentrated solution of hydrochloric acid, after that, 100-200 ml of distilled water are added, after evaporation of the solution on a water bath for 5 min to complete dehydration of hydrated silicon (IV) oxide and control of the medium pH by titration with a 0.1 M solution of potassium hydroxide with methyl orange, separation of silicon (IV) oxide by filtration is performed with collection of filtrate through a non-compact ash-free filter into a cup and washing of the sediment with a 0.5% solution of hydrochloric acid to the negative reaction to ions of iron (III) with rhodanide. Control of the medium pH with titration with a 0.1 M solution of potassium hydroxide with methyl orange is carried out. The sediment drying is carried out on the filter, and then in the Petri dish in an exsiccator at a temperature of 90-120°C.

EFFECT: invention makes it possible to reduce labour consumption of the process of melt leaching from the crucible, which is an economical and energy-preserving factor, and increase the output of finely disperse amorphous microsilica.