A Multi-analytical Approach to Understand the chemistry of Fe-minerals in Feed Coals and Ashes

Marcos Oliveira, Frans Waanders, Luis Silva, Andre Jasper, Carlos Sampaio, Dursman McHabe, Rachel Hatch, James Hower
2011 Coal Combustion and Gasification Products  
A B S T R A C T Seven feed coals used in the Brazilian power generation industry were obtained and subsequently analysed together with fly ash and bottom ash from a major Brazilian power plant. The samples were investigated by means of room temperature Fe-Mö ssbauer analyses, X-ray diffraction, Raman spectroscopy, scanning electron microscope and petrographic analysis. In addition, nanometer-sized crystalline phases in coals and ashes were characterised using an energy-dispersive X-ray
more » ... sive X-ray spectrometer and a high-resolution transmission electron microscope. The major identified Fe-bearing minerals in the coals were found to be actinolite, ankerite, chalcopyrite, chlorite, goethite, illite, ilmenite, magnesioferrite, natrojarosite, pyrite, pyrrhotite, and siderite; whilst in the fly ash and bottom ash, ankerite, chlorite, chromite, goethite, hematite, hercynite, jarosite, maghemite, magnesioferrite, and magnetite were identified. Most of the Fe in the ash samples was present as Fe 3+ resulting from the melting of Fe and silicates during combustion. The fraction of glassy Fe in those particles is high because of the high contact probability between Fe melt and silicates. The combination of the various methods offers a powerful analytical technique in the study of coal and coal ashes. This investigation can be regarded as an introductory and prospective study prior to further quantification.
doi:10.4177/ccgp-d-11-00006.1 fatcat:7sdlupd7ybeojmr7hrziann3by