Characterization of coals by automated optical image analysis 2. Inertinite reflectance

Abstract

SUMMARYIt is now well established that the combustion and carbonization behaviour of the coal maceral group inertinite is correlated with its reflectance. Inertinite reflectance studies have shown that, whereas accurate measurement by conventional optical microscopy is a prohibitively time‐consuming operation, image analysis techniques are limited by their inability to distinguish vitrinite and inertinite with the same grey level. Nevertheless, automated inertinite reflectance measurement has been used to demonstrate a potential quantitative distinction between fusinite and semifusinite. Furthermore, the proportions of vitrinite and inertinite in a coal sample can be determined by image analysis as accurately as by conventional methods.Reflectance distributions including all components within a coal have also been investigated; this could provide a way of characterizing coals, in particular inertinite‐rich ones, without the need for maceral identification. This approach is almost free of subjective interpretation; however, there are some limitations due to erroneous measurements at inter‐maceral boundaries. The reproducibility of this procedure between different laboratories is sufficiently encouraging to consider its use in a quality control environment.