EFFECT OF ALKALINE ADDITIVES ON THE SINTERING PROCESS OF SILICEOUS FLY ASHES

摘要

Fly ashes are captured in the standard dedusting systems in three sections of the electrofilter located in series behind the combustion chamber. Fly ashes captured by the last, third section of the elecrofilter can be used as a raw material in the production of ceramic materials with sintered body such as stoneware and clinker bricks. The grain size distribution and phase composition of fly ashes captured by the third section of the electrofiiter intensify sintering processes and accelerate the appearance of liquid phase. The purpose of this research was to modify the physical and chemical properties of those fly ashes in order to further intensify the sintering processes in ceramic mixtures doped with them. The studied fly ashes were modified by means of milling or by incorporation of alkaline or alkaline earths carbonates. The milling increased slightly densification ability of the ashes and therefore the properties of the sintered materials. The chemically modified ashes enriched with Na2O, K2O or CaO did not show the improved densification ability when compared to the unmodified ones.