Mineralogy and Geochemistry of Feed Coals and Combustion Residues from Tunbilek and Seyitmer Coal-Fired Power Plants in Western Turkey

Abstract

This study focuses on the enrichment of elements in feed coal (FC) and combustion residues, namely, fly ash (FA) and bottom ash (BA) samples, picked up from the Tuncbilek and Seyitomer coal-fired power plants in western Turkey. The FCs in both plants have generally similar mineralogical compositions, although siderite and dolomite are more prominent in Tuncbilek and feldspar and pyrite are more abundant in Seyitomer. Minerals in the FA from both power plants are mainly quartz, hematite, magnetite, anhydrite, and mullite. Along with quartz, the Fe-oxides are dominant phases in the BA samples. Accessory minerals in the FCs, FAs, and BAs, such as chromite and pentlandite, were identified by combined scanning electron microscopy-energy dispersive X-ray analysis. Significant enrichments of Cr and Ni were detected in FCs, FAs, and BAs from both power plants. These enrichments are probably associated with pyrite, chromite, and pentlandite. Mercury was also significantly enriched in the Seyitomer FA, owing to Hg retention by chars and anhydrite. The Hg and Cl concentrations of char samples from FAs of both power plants indicate that Hg and especially Cl concentrations are much higher than those in the FCs.