Physico-chemical characteristics of European pulverized coal combustion fly ashes

Fly ashes sourced from European pulverised coal burning power plants (from Spain, The Netherlands, Italy and Greece) were characterised in terms of their chemical composition, mineralogy and physical properties. The amount and composition of the glass present in the ashes were also determined. The materials analysed have very different compositions and were selected with a view to determining their suitability for different applications and for further studies on applications. The results were compared to the literature to determine their similarities to UK coal fly ashes. Chemical analysis has enabled the categorisation of the ashes based on their oxide contents. Devitrification of the glass phase has been effected using suitable heat treatments and crystal phases formed are used as an indicator of glass reactivity. Based on leaching tests, certain ashes were identified as having limitations for some further uses due to the relatively high levels of leachable trace elements. A wide range of physical properties such as density were observed and these are related to factors such as mineralogical content and particle morphology.