Morphology and chemical composition of mineral matter present in fly ashes of bituminous coal and lignite
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ORIGINAL PAPER
Morphology and chemical composition of mineral matter present in fly ashes of bituminous coal and lignite E. Strzałkowska1 Received: 2 August 2020 / Revised: 8 October 2020 / Accepted: 31 October 2020 © The Author(s) 2020
Abstract The changing properties of energy waste force us to look for alternative directions of their use. The aim of the research presented in this paper was to indicate the possibilities of managing fly ashes from bituminous coal and lignite based on the observation of individual particles of these ashes. Innovative research techniques were used, among others: SEM with EDS detector and Image Analysis. Microscopic observations have shown that fly ashes are a heterogeneous material composed of particles occurring in three basic morphological forms: spherical, irregular and fine-detritic. A high proportion of spherical particles was found in bituminous coal ashes (rich in SiO2 and Al2O3), which gives them high pozzolanic activity. This kind of morphology and chemical composition make these ashes a potential material for zeolites synthesis. The amorphic phase of ash from lignite coal has aluminium–silicate-calcium chemical composition, which is what determines pozzolanic and hydraulic properties of these ashes. Magnetic separation of iron-rich particles may be a way to manage the researched ashes. One of the valuable components of hard coal ash are microspheres, which are characterized by high variability in chemical composition, so further utilization will require prior refining. The main component of irregular particles found in ashes is unburned coal and, to a lesser extent, a mineral substance. The separation of all useful components from the tested ashes before their further management will allow the full use of their raw material potential. Keywords Ferrospinels · Fly ash · Mineral matter · Microspheres · Morphology Abbreviations AR Aspect ratio EDS Energy dispersive spectroscopy LOI Loss on ignition SEM Scanning electron microscope WB WB Fly ash from lignite combustion WK Fly ash from bituminous coal combustion
Introduction Fly ashes, created as a result of burning coal in power plants, have some specific properties, which that allow their various uses. Attempts of using these side products of burning in diverse ways have been made for years and Editorial responsibility: Shahid Hussain. * E. Strzałkowska [email protected] 1
Department of Applied Geology, Faculty of Mining, Silesian University of Technology, Safety Engineering and Industrial Automation, Akademicka 2, Gliwice, Poland
are ecologically beneficial as well as economically. One of the most significant recipients of fly ashes is building materials industry, where they are used as mineral additive in the production of cement, multi-component binders or concrete. (Galos, Uliasz-Bocheńczyk 2005; Giergiczny 2013; Uliasz-Bocheńczyk et al. 2015). To a slightly lesser extent, ashes are used in the production of special ceramics or thermal insulation materials (Erol et al. 2008b; Stoch 2015). Expansio
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