CHEMICAL-COMPOSITION AND SIZE DISTRIBUTIONS FOR FLY ASHES

Inter-particle variations in particle diameter and chemical compositio n in coal fly ashes are significant, and can be quantitatively studied using currently available microanalytical techniques, One such techni que, computer controlled scanning electron microscopy (CCSEM), is now routinely used to determine chemical compositions and diameters of ind ividual fly ash particles, using statistically significant sample size s. This paper proposes simple mathematical formulae for expressing the inter-particle variations. Additionally, these formulae can be used f or economically storing the large amount of data generated by CCSEM. T wo apparent limitations of the CCSEM technique are discussed - one rel ating to the measurement of size distribution, and the other to determ ining the iron oxide distribution in the ash. These limitations are im posed by statistical considerations, and by artifacts of sample prepar ation techniques.