Mineral matter and trace elements in Miocene coals of the Tuncbilek-Domanic basin, Kutahya, Turkey

Abstract

The Tuncbilek-Domanic basin, which is one of the most productive coal basins of western Anatolia-Turkey, contains a thick and lateral extensive coal bed at the base of the Miocene Tuncbilek Formation. The coal bed sampled in this study has a thickness of 3-10 m. The coals are produced both by underground and mainly open-cast mining methods. Eight channel samples, which represent the full thickness of the coal bed, were collected from different coal mines and evaluated in this study. The samples show that the coal bed, on an air-dried basis, has high ash yields (29.8-55.5%), a large range of total sulfur contents (0.61-4.48%), and calorific values (2,433 4,834 kcal/kg). The mean values of random reflectance, in oil, of ulminite, which are between 0.42 and 0.51%Rr (av. 0.46%), and nonagglomerating character imply that the coals are in a subbituminous coal rank. The mineral matter of the whole-coal samples was identified by X-ray powder diffraction. This study shows that the samples are mainly made up of clay minerals (smectite, illite, and kaolinite/chlorite) and quartz and minor/trace amounts of siderite, dolomite, and pyrite. Moreover, some samples contain appreciable contents of feldspar, calcite, gypsum and opal-CT, and jarosite. Petrographic studies show that some massive pyrites, calcites, and dolomites were detected in cleat and fracture infillings. Elemental results were determined using an energy dispersive, polarized X-ray spectrometer (EDP-XRF) on a whole-coal dry basis. Ten trace elements (As, Co, Cr, Mn, Ni, Pb, Sb, Se, Th, and U), considered as potentially hazardous air pollutants, are present in low to moderate concentrations. The Cr and Ni concentrations in all of the samples and As, Co, Mn, Se, Th, and U concentrations in some samples display relative enrichments in comparison to other coals in the world.