| 摘要 |
FIELD: mining industry. ^ SUBSTANCE: invention relates to technology of processing mineral raw materials and can be used to produce amorphous silica from various types of silica-containing raw materials: quartz sands, kaolin clays, concentrates, man-caused wastes, and the like. Processing method comprises mixing silica-containing raw material with ammonium hydrodifluoride or fluoride at weight ratio 1:(2.3-2.8). Mix is heated to 170-220°C and kept in hot state until powderlike cake is formed, from which volatile ammonium-containing fluorides are sublimed in oxidative medium while simultaneously blowing with water steam or under reductive or inert conditions at temperature at least 350°C to form volatile ammonium hexafluorosilicate. The latter is dissolved in water to concentration 10-25% and brought into reaction with aqueous ammonia at 30-90°C to form suspension, which is kept in hot state until amorphous silica is formed. This product is then recovered in the form of solid precipitate. ^ EFFECT: increased yield of high-quality improved quality amorphous silica at lower usage of starting materials and power consumption. ^ 3 ex |
