Production Of Fired Ceramic Materials From Fly Ash With Witherite Additive

Abstract

In this study, the effect of witherite (BaCO3) addition on the sintering of lignite coal fly ash taken from the Seyitomer power plant of Kutahya/Turkey was examined at temperatures of 1100, 1150 and 1200 0C in air atmosphere. Bloating of the fly ash samples sintered at 1150 0C was prevented by shifting the decomposition temperature of CaSO4 in the fly ash to a higher temperature, and their physico- mechanical properties (porosity, water absorption, bulk density and bending strength) were improved with BaCO3 addition owing to the phase transformation from CaSO4 (anhydrite) to BaSO4 (Barite) as supported by XRD analysis. Positive effects of BaCO3, however, were not seen on the fly ash samples sintered at 1100 0C. All the fly ash samples sintered at 1200 0C were bloated due to the gas evolving during the thermal decomposition metal sulphates, and also they melted.