Fusibility Assessment for Coal

The aim of the project was to calibrate the CSIRO scanning fluorescence laser microprobe (SLFMP) against the results of coal-to-coke mass balance calculations to provide a rapid and inexpensive method of assessing the proportion of fusible macerals in single seam coals and blends. In the course of the project, calibration has been carried out using a suite of Australian and German coals, optimum instrumental conditions have been defined, and methods of data collection and processing have been developed so that a routine-determination-of fusibility by the SLFMP can be completed in a commercially realistic time of two hours. Results from the SLFMP technique, however, are only valid over the main range Ro(max) = 0.8 - 1.5% of coking coals. The SLMFP technique has been shown to have some industrially important applications in coal oxidation and blending studies. In a study of the sequential oxidation of an Australian coking coal at ambient temperature, the fusible maceral content was found to decrease by a few percent absolute over a period of four months. Such observations, which are otherwise very difficult to quanta, could be the basis of a test to evaluate oxidation effects on coking coals in transport and storage. The technique has also been applied to the assessment of fusible macerals content in blends. For two blends there was excellent agreement between the SLFMP and coal-to-coke mass balance calculations results. For another two blends which contained a high volatile component outside the working range of rank of the SLFMP, the fusible macerals values given_, by the two techniques did not agree well, apparently due to the comparatively large reduction in mass of this component during carbonisation. Where out of . range components are used in blends, corrections to the SLFMP fusibility values would have to be made.