The proximate and ultimate analyses of coals are commonly regarded as suffi
cient for a satisfactory description of their chemical composition. This is
no doubt true if coal is considered as a whole, but it has to be borne in
mind that coals are actually composed of fairly different materials (macera
ls), and that the corresponding chemical characterization data are average
values of the individual compositions of the macerals present in the coal.
As regards the determination of coal maturity, the volatile matter content
is widely used as a rank parameter, although this characteristic varies not
only with coalification but also with maceral composition. A full descript
ion of the chemistry of coals, for the prediction of their behavior during
industrial processing, requires that the characteristics of their maceral c
omponents is also known. This paper is an attempt to evaluate the relative
contributions of vitrinite, liptinite, and inertinite to the volatile matte
r content of coals, over the entire coalification scale. Proximate and petr
ographic analyses were carried out on 39 coals, and data from 992 more coal
s and 83 coal fractions were obtained from the literature and coal database
s. A best-fit strategy was run with these data, so that the volatile matter
contents of the three maceral groups and their variations with rank were d
etermined. The results showed qualitative trends similar to those reported
in the literature, but a substantial improvement in their predicting abilit
y was achieved, and the ranges of applicability were expanded to the entire
coalification scale.