Influence of particle composition on the ceramic behaviour of flyash

Typical run-of-station PFA existing the power station boiler, entrained in the flue gases, is a complex mixture of particle types and sizes, each, with its own distinctive ceramic characteristics. This pre-fused material, needing less 'heat work' to achieve vitrification in a body, plus the calorific value of associated carbonaceous matter, offers a potential in energy saving, when introduced as admixtures in the production of ceramic building products. To provide consistent PFA suitable for incorporation into commercial clay-ware bodies to promote the energy saving benefits available, the options are selective take-off and blending, or beneficiation. The latter route, with air classification of the variable material from power station disposal silos to yield products of predictable size and selected ceramic properties, appears to be the more viable.