GB668612A - Method of producing coarsely crystalline sodium carbonate monohydrate - Google Patents

Abstract

Coarsely crystalline sodium carbonate monohydrate is produced by mixing sodium carbonate from the ammonia soda process, preferably immediately after calcination and while still hot, with the water required for the formation of the monohydrate, e.g. 20-50 per cent preferably in the form of steam, the mass being kept in motion at 70 DEG C. while maintaining the water content, suitably by working in a closed apparatus. Excess water is preferably used which may be removed by passing a current of warm air over the mass at completion. The resulting coarse grained monohydrate may be calcined at about 130 DEG C. to give coarse grained sodium carbonate. An example relates to the treatment of calcined ammonia-soda with steam in a closed rotating drum until 20 per cent of water has been absorbed. The temperature rises to 105 DEG C., the steam is cut off and the temperature maintained between 90 DEG -100 DEG C. for 50 minutes. Air is passed over at 40 DEG -60 DEG C. to remove excess water. A further example relates to treatment with water at 80 DEG C. It is stated in the Specification to be known that granulated dense soda may be produced by mixing soda of low bulk density with 16 per cent of water in a screw mixer and subsequently drying at 135 DEG -190 DEG C., the steam from the drier being condensed and recycled to provide the 16 per cent of water required for hydration.