Mineral and chemical composition and some trace element contents in coals and coal ashes from Huaibei coal field, China

The mineral and chemical compositions and some trace element contents (As, Ba, Cr, Mn, Mo, Sb, Th, U and V) in coal and coal ash samples from the Huaibei coal field in China were studied. This high volatility bituminous coal has low moisture and S contents, moderate ash yield and high calorific value. The coal ash is abundant in aluminosilicates as the contents of the Fe oxides are relatively similar to the sum of the alkaline earth oxides. The minerals identified in the coal are mainly quartz, kaolinite, pyrite and calcite and, to lesser extents, dolomite, ankerite, illite, chlorite, opal, feldspars, marcasite, gypsum, melanterite and hematite. Common minerals in the high temperature ash (815 °C) are original quartz and newly formed anhydrite, lime, hematite and Ca–Mg silicates. Some trace elements such as Cr > Th > V > Mo in the coal (in particular Cr and Th) and Cr > Th > V in the coal ash (in particular Cr) are enriched in comparison with the Clarke concentrations.