Abstract:
The occurrence and distribution of mineral matter in 35 coal products samples was determined by means of radio-frequency ashing and X-ray diffraction. The association of illite with high rank coals in contrast with that of kaolinite with low rank coals is thought to be due to neoformation during late diagenesis coincident with the intrusion of dolerites. The distribution of non-crystalline material in the coal products may perhaps also be due to metamorphism. The impoverishment Si02, MgO, Na20 and K2O in coal ash, and the enrichment of Al2O3 and TiO2 relative to the earth's crust is thought to be due to acid leaching and the activities of plants. The calculated argillaceous norm from the ash analysis differs from the determined mineral composition but can serve as an estimate of the total mineral matter content of the coal. The few trace element determinations show a strong enrichment of tungsten in coal ash and underline the need for further trace element determinations.