Spherical particles of anhydrous sodium metasilicate and method of manufacture thereof

Claim 1

A PROCESS FOR MANUFACTURING SUBSTANTIALLY ANHYDROUS CRYSTALLIZED SODIUM METASILICATE WICH COMPRISES CARRYING OUT THE FOLLOWING STEPS: (A) INTRODUCING A PLURALITY OF SMALL SOLID PARTICLES NO LARGER THAN 48 MESH OF CRYSTALLIZED ANHYDROUS SODIUM METASILICATE AT A TEMPERATURE ABOVE 130*C. INTO A COATING ZONE SO AS TO FORM A MOVING MASS OF SMALL CRYSTALLIZED PARTICLES, (B) ALSO SPRAYING INTO SAID COATING ZONE AQUEOUS SODIUM METASILICATE LIQUOR WHICH HAS A BOILING POINT ABOVE 105*C. AND THEREBY COATING A LIQUID FILM OF SAID AQUEOUS SODIUM METASILICATE LIQUOR ON AT LEAST A SUBSTANTIAL PORTION OF THE EXTERIOR SURFACE OF SAID MOVING MASS OF SMALL PARTICLES OF SOLID CRYSTALLINE ANHYDROUS SODIUM METASILICATE THUS CAUSING THE LIQUOR TO CRYSTALLIZE AS A LAYER OF ANHYDROUS SODIUM METASILICATE ON THE SMALL PARTICLES, (C) MAINTAINING SAID MOVING MASS OF FILM COVERED PARTICLES ABOVE THE BOILING POINT OF THE AQUEOUS SODIUM METASILICATE LIQUOR BY APPLYING ADDITIONAL HEAT IN THE FORM OF A HEATED GAS STREAM SO AS TO CAUSE EVAPORATION FROM SAID LIQUOR FILM OF WATER FREED BY SAID CRYSTALLIZATION, (D) REPEATING THE ABOVE COATING AND FILM CONVERSION STEPS UNTIL THE SIZE OF THE ANHYDROUS CRYSTALLINE SODIUM METALSILICATE PARTICLES HAS INCREASED TO THE DESIRED EXTENT.