MINERAL MATTER IN COALS OF DIFFERENT RANK FROM THE ASTURIAN CENTRAL BASIN

The mineralogy of three coals of different rank (from high volatile to low volatile bituminous coal) from the Asturian Central basin (NW Spain) was characterized. For this, low temperature ashing residues of coals were studied by X-ray diffraction. FT-i.r. spectroscopy and analytical electron microscopy. The main inorganic elements were analysed in high temperature ashes by both atomic absorption spectrometry and X-ray fluorescence spectrometry. The joint use of these techniques provided a detailed insight into the characteristics (nature, origin, morphology) of the various minerals found. The mineralogical composition of coals from the Asturian Central basin is very similar for the various samples despite differences in coal rank. Mineral species present are, in decreasing order of abundance, clay minerals (illite, kaolinite, mixed layer illite-smectite, chlorite), quartz, carbonates (calcite, siderite and ankerite), pyrite and feldspars.