PROCESS FOR THE PREPARATION OF CALCIUM SULPHATE ANHYDRITE AND CURABLE CALCIUM SULPHATES

摘要

1. A process for preparing calcium sulfate anhydrite and calcium sulfates capable of setting by the reaction of calcium sulfate dihydrate with acids at elevated temperatures, characterized in that a finely divided calcium sulfate dihydrate is heated with from 0.5 to 7% by weight, and preferably from 1 to 3%, of sulfuric acid, phosphoric acid or mixtures thereof with a total liquid content of the mixture of less than 20% by weight, and preferably of between 5 and 14% by weight, at a temperature from 50 degrees C to 130 degrees C, and preferably from 70 degrees C to 100 degrees C, for a definite period of time and optionally is neutralized with the equivalent amount of calcium hydroxide.