Production of an ultrafine silicon dioxide powder comprises heat treating a raw material mixture containing silicon dioxide powder, a reductant and water, cooling and collecting the fine particles

摘要

Production of an ultrafine silicon dioxide powder comprises heat treating a raw material mixture containing a silicon dioxide powder, a reductant made of a metallic silicon powder and/or carbon powder, and water at a high temperature in a reducing atmosphere having an oxygen concentration of less than 1 wt.% to produce a SiO2-containing gas, directly cooling the gas in an oxygen-containing atmosphere and collecting fine particles.