VERFAHREN ZUR HERSTELLUNG VON NATRIUMSILIKATEN

For the preparation of amorphous sodium silicates having a water content from 0.3 to 6% by weight and an SiO2/Na2O molar ratio of (1.9 to 2.8):1 from a waterglass solution obtained by reacting sand with sodium hydroxide solution in an SiO2/Na2O molar ratio of (2.0 to 2.8):1 and having a solids content of at least 20% by weight, the waterglass solution is treated in a spray-drying zone with hot air at 200 to 300 DEG C to form a pulverulent, amorphous sodium silicate having a water content (determined as loss on ignition at 700 DEG C) of 15 to 23% by weight. The spray-dried, pulverulent, amorphous sodium silicate is first ground, preferably to grain sizes of 1 to 50 mu m, before it is introduced into a rotary kiln in an inclined arrangement and treated therein with flue gas in countercurrent at temperatures of 250 to 500 DEG C to form pulverulent, amorphous sodium silicate. The sodium silicate emerging from the rotary kiln is comminuted to grain sizes of 0.1 to 12 mm and finally ground to grain sizes of 2 to 400 mu m.