Process for the production of crystalline sodium disilicate in a

Details Process for the production of crystalline sodium disilicate in a Process for the production of crystalline sodium disilicate in a

1992-12-08

1994-05-03

Chaudhuri, Olik

Chemistry of inorganic compounds

Silicon or compound thereof

Oxygen containing

423334, 252135, C01B 3332

Patent

active

053085965

ABSTRACT:
To prepare crystalline sodium disilicates having a laminar structure, a molar ratio of SiO.sub.2 to Na.sub.2 O of (1.9 to 2.1) 1 and a water content of less than 0.3% by weight, a water glass solution is first obtained by reacting sand with sodium hydroxide solution in a molar ratio of SiO.sub.2 to Na.sub.2 O of (2.0 to 2.3) : 1 at temperatures of 180.degree. to 240.degree. C. and pressures of 10 to 30 bar. This water glass solution having at least 20% by weight of solids is treated in a spray drier with hot air at 200.degree. to 300.degree. C. with the formation of a pulverulent amorphous sodium disilicate having a water content (determined as loss on heating at 700.degree. C.) of 15 to 23% by weight and a bulk density of at least 300 g/l. The spray-dried pulverulent, amorphous sodium disilicate is ground. The ground sodium disilicate is introduced into a rotary kiln equipped with devices for moving solids, externally heated via the wall and having in its interior a plurality of different temperature zones, and is treated therein at temperatures of 400.degree. to 800.degree. C. for 1 to 60 minutes with formation of crystalline sodium disilicate.

REFERENCES:
patent: 3838192 (1974-09-01), Bertorelli et al.
patent: 3956467 (1976-05-01), Bertorelli
patent: 4806327 (1989-02-01), Rieck et al.
patent: 5183651 (1993-02-01), Schimmel et al.
patent: 5211930 (1993-05-01), Schimmel et al.
Perry's Chemical Engineers' Handbook (6th Ed.), Green & Maloney (ed), 1984, pp. 20-29 to 29-38.

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