coal mill fineness astm Pochiraju Industries Ltd
Fly ash Wikipedia, the free encyclopedia. Depending upon the source and makeup of the coal being burned, the. Two classes of fly ash are defined by ASTM C618: Class F fly ash and Class C fly ash. 75% of the ash must have a fineness of 45 #181;m or less, and have a carbon content, due to changing performance of the coal mills and the boiler performance.