Analysis, origin and significance of mineral matter in coal: An updated review

Processes responsible for mineral matter formation include detrital input, biogenic activity, and authigenic precipitation at different stages of the coal's depositional and post-depositional history. Differential migration of non-mineral inorganic elements may also occur in lower-rank coals, and expulsion of non-mineral inorganics may take place with rank advance. Knowledge of the mineral matter may be of assistance in understanding the modes of trace element occurrence, with implications for assessing possible environmental impacts and also the potential for recovery of economic products from coal. The behaviour of different mineral matter components at high temperatures is also discussed, as well as methods for mineralogical analysis of ashes and other coal utilization products. Information from mineral matter studies may provide an improved basis for understanding coal formation, and for evaluating the response of particular coals to different combustion, gasification and coking processes.