THE ROLE OF SULFATE-SILICATE PHASE-SEPARATION IN THE SINTERING PROPENSITIES OF COAL FLY-ASH AT 800-1000-DEGREES-C

Sulphation of both Shoshone fly-ash and its amorphous form may occur u p to about 10% wt of SO3. Above that composition, sulphates are separa ted from silicates and may create necks between silicate particles. Th ere is evidence that sulphated ash may consist of species with sodalit e structures such as hauyne, with maximum sulphur content between 5 an d 8% wt. These may stabilise the sulphated silicate-sulphate interface below 1000 degrees C.