The present state of the methods commonly used for characterization of the phase, mineral,
and chemical composition of fly ashes from coal-fired power stations is described and summarized.
The application of various methods is briefly discussed; these methods include macroscopic
observations, ashing procedures (high-temperature and low-temperature), physical separations
(density, magnetic, particle size, froth flotation, and electrostatic), chemical leaching, sequential
physical and chemical treatments, as well as optical microscopy (reflected and transmitted),
electron microscopy (scanning and transmission), X-ray diffractometry, differential thermal and
thermogravimetric analyses, Mössbauer and infrared spectroscopy, and different chemical
analyses. A short critical overview on the advantages and limitations is given, as well as certain
recommendations during application of the above-listed methods. Some considerations about the
practical use of data for fly ash composition are also present.