Recovery of carbonaceous solid residue (char) from coal ash to use as possible substitute graphite-based materials in green energy applications.

ANA CLAUDIA SANTOS; BADENHORST CHARLOTTE; BARBARA BIALECKA; CALUS-MOSZKO JOANNA; LUMINITA POPESCU; MIHAI CRUCERU; GEORGETA PREDEANU; JUAN MANUEL LÁZARO MARTÍNEZ; TRAIAN ABAGIU

St Louis

Conferencia; World of Coal Ash Conference (WOCA) 2019; 2019

American Coal Ash Association (ACAA)

Results from an ERA-MIN funded collaborative project (?Charphite?) between Portugal, Poland, Romania, South Africa, and Argentina are presented. The char found in coal ash is evaluated as a precursor for synthetic graphite (and subsequent application in green energy technologies). The initial coal ash samples were characterized in detail. The extraction process of char from a South African fly ash is discussed as a case study. Final characterization results on the char concentrates from four countries are presented in terms of potential graphitizability.All initial coal ash samples were characterized using proximate, carbon forms, X-ray fluorescence, X-ray diffraction, petrography, solid-state Nuclear Magnetic Resonance, and particles size distribution analyses.A combination of size, electrostatic, magnetic, and density extraction techniques were used to concentrate the char. It was found that the carbon grade increased from 7.04 wt. % to 82.91 wt. % LOI (loss in ignition) for the South African fly ash sample. The overall carbon recovery was 18.92 %.All final char concentrates were characterized using proximate, ultimate, carbon forms, petrography (char form and reflectance), and Micro Raman Spectroscopy.The Romanian char concentrate showed a disordered nature and high percentages of volatile matter, organic carbon, unreacted coal, and isotropic char were encountered. Micro Raman Spectroscopy classified this material as ?amorphous? with the presence of a broad G band. The char concentrates from Portugal, Poland, and South Africa were classified as transitional carbon material with the possibility of graphitization. Elemental carbon and anisotropic percentages in these three samples were high.