Study of the chemical composition of coal and coal ash by X-ray fluorescence method: A review

Information about the elemental compositions of coal and coal ash is very important to solve some issues related to both technological processes and the control of environmental pollution. It is known that the coal and coal ash samples often contain significant amounts of valuable as well as toxic components (e.g., V, Cr, & Scy;& ocy;, Ni, Cu, Zn, As, Sr, Ba, Pb, Ga, and Ge) that can be successfully determined by X-ray fluorescence (XRF) spectrometry. This review briefly discusses the development of XRF equipment, elements of interest determined by XRF, and common sample preparation procedures. The calculation of relative intensities of analytical lines of some elements and scattered radiation is presented to demonstrate possible matrix effects in XRF analysis. Possibilities and drawbacks of total reflection XRF (TXRF) are described in detail as the coal and ash analysis is a relatively new area of application of TXRF method. The review also presents examples of the application of the XRF method for analysis of waste from coal preparation plants and thermal power plants to assess their prospects and to choose a method for extracting individual elements. Among the reviewed publications, several works are devoted to the study of the element distributions, especially rare earth elements, in coals, coal ash, and coal waste.