The heterogeneity of the 125-212 mu m size cuts from four pulverized coal s
amples from the United Kingdom, United States, and South Africa has been ex
amined in detail by means of density separation and optical and scanning el
ectron microscopy. While average properties of the overall size cut samples
are similar to those of the parent coals, a high degree of heterogeneity e
xists between average compositions for the different density cuts within ea
ch sample, between different particles within the same density cuts, and, i
n many cases, within the particles themselves. Conventional analyses are un
suited for describing this heterogeneity and an alternative descriptive met
hod based on maceral associations has been used, together with illustrative
micrographs. The implications of coal heterogeneity for particle behavior
during grinding, pulverized coal combustion and coal characterization for m
odeling purposes are discussed.