METHOD FOR PRODUCING OF SILICON DIOXIDE WITH LOW CONTENT OF INORGANIC IMPURITIES OF RICE HUSKS

摘要

The invention relates to producing of powdered silicon dioxide from rice husks, which is used in the chemical industry, electronics and for the production of optical and glass-ceramic materials with high thermal stability and hardness. The method provides the production of silicon dioxide with size of the particles of 10 to 20 nm and a total content of inorganic impurities from 100 to 50 microg.g-1 at less energy consumption. The method consists of burning of the rice husks in oxidizing atmosphere and dissolving of the ash residue in alkaline base. The alkaline solution is passed trough a system of ion exchange columns. The resulting sol comprises various forms of the silica acid, which are dehydrated by heating, when passing in nanostructured silicon dioxide with high purity.