Abstract
Fly ash from coal-fired electric power plants contains much unburned carbon recently. This causes problems in its utilization as a raw material for fly ash cement and as a cement admixture because of the need to lower the combustion temperature to reduce air pollution.
This study on the basic properties of fly ash suggests that it is possible to remove unburned carbon from fly ash on the basis of both the variation in carbon content with particle size and the difference in shape between unburned carbon particles and ash.
Classifying raw fly ash at a certain cut size by means of a sifter without the fracture of particles of a larger size rich in unburned carbon, the fly ash with low unburned carbon content was undersized. Subsequently, by processing most of the oversize fly ash on an inclined vibrating plate, the relatively round fly ash having a low unburned carbon content was separated from unburned carbon particles having an irregular shape.
Thus, it is concluded that fly ash with low unburned carbon content can be recovered using both of the above-mentioned methods.
