PROCESS FOR PREPARING CRYSTALLINE SODIUM SILICATE HAVING LAMINATED STRUCTURE Russian patent published in 1995 - IPC

FIELD: process for preparing crystalline sodium silicate having a laminated structure at a SiO₂:Na₂O = (1,9-2,1):1 molar ratio and a moisture content of less than 0.3 wt % from liquid glass having the minimum solid content of 20 wt % . SUBSTANCE: glass is produced by reacting quartz sand with a sodium hydroxide solution at a SiO₂:Na₂O = (1,9-2,1):1 molar ratio at 180-240 C and at a pressure of 10-30 bar. The resulting liquid glass is treated in a spraying drying zone first with air at 200-295 C for 10-25 s and then st 90-127 C with the gas that is leaving the spraying drying zone till an amorphous powdery sodium silicate is formed having a moisture content (established as losses during the calcination process at 700 C) of 15.8-22.8 wt % and a bulk weight of more than 30 g/dm³. The liquid glass is then placed into a rotary tubular furnace provided with an inclined device for the travel of a solid. The liquid glass is then treated in a countercurrent of flue gas at 500-800 C till crystalline silicate is formed. In this case the rotary tubular furnace is insulated so that its exterior wall may have a temperature of less than 60 C. The crystalline silicate is thereafter ground to a particle size of form 0.1 to less than 6 mm by means of a mechanical crusher. EFFECT: improved properties of crystalline silicate. 4 cl, 1 tbl