Process for preparing sodium carbonate

Claim 1

A PROCESS FOR PREPARIANG DENSE ANHYDROUS SODA ASH WHICH COMPRISES FORMING A SLURRY BY ADDING LIGHT SODA ASH TO AN AQUEOUS SOLUTION MAINTAINED AT ABOUT 95* TO 110* C. SATURATED AT THAT TEMPERATURE WITH DISSOLVED SODADA ASH AND CONTAINING FROM ABOUT 5 TO 15 PERCENT OF CAUSTIC SODA BASED ON THE WEIGHT OF THE WATER AND DISSOLVED SODA ASH, COOLING THE SLURRY TO ABOUT 88 TO 104*C. BUTT NOT LESS THAN 2*C. AND NOT MORE THAN 7*C. BELOW THETHE TEMPERATURE OF TRANSITION OF ANHYDROUS SODA ASH TO ITS MONOHYDRATE IN THE PRESENCE OF THE CAUSTIC,HOLDING THE SLURRY AT THE REDUCED TEMPERATURE UNTIL THE TRANSITION OFF ANHYDROUS SODA ASH TO ITS MONOHYDRATE IS ESSENTIALLY COMPLETE, SEPARATING THE SODIUM CARBONATE MONOHYDRATE FROM THE SLURRY AT THE REDUCED TEMPERATURE, DRYING AND CALCINING THE MONOHYDRATE TO ANHYDROUS, DENSE SODA ASH.