PROCESS FOR PREPARING HIGHLY DISPERSIVE SILICON DIOXIDE Russian patent published in 1994 - IPC

FIELD: tire industry. SUBSTANCE: a 15-28% hexafluorosilicic acid solution is sprayed in 55-80% of the total amount of ammonia water in a stream at a Weber criterion value of (0,005-2)·10⁴. The resultant suspension is kept under stirring for 20-30 min, cooled to 25-30 C and delivered to the 2nd deposition step by spraying to the remaining amount of ammonia water. The suspension is then kept under stirring for 20-30 min, filtered under rarefaction, washed and the resulting deposit is dried. The filtration coefficient (1,35-2,72)·10⁵ cm/s; the specific area 179-250 m²/g; the bulk density 114.0-217 g/l. EFFECT: improved properties of the title product. 2 cl, 1 tbl