Ash composition of the main Albanian coals

Coal ashes from 17 mines were analysed in terms of ash yield and percentages of SiO2, Al2O3, Fe2O3, CaO, MgO, K2O, Na2O, TiO2, P2O5, MnO, NiO. The composition has been analysed in terms of: (1) contribution to ash contents; (2) acidic, amphoteric and basic oxides; (3) co-ordination number in solid state; (4) fluxing components; (5) cement-constituting minerals; (6) periodical table. Significant correlations were observed on expressing the percentage in mol% or ion% and not in wt%. The decrease in basic oxides was associated with an increase in acidic ones.