Characterization of biomass and high carbon content coal ash for productive reuse applications

Alkali-activation potential of biomass-coal co-fired fly ash

“…B-CA-4 and C-CA-15 also have a lower amorphous glassy content compared to A-FA-0, after subtracting the amorphous phase associated with organic carbon in these ashes. Previous work in characterization of these ashes found that the major M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 6 differences observed here (especially with regard to the alumina, silica and carbon content) are more a function of production variables (e.g., pulverization process, oxygen levels and furnace temperature) and the raw coal properties, rather than the biomass properties [13,14]. The carbon content is also the main parameter controlling surface area in these ashes, because the residual carbon has a very high specific surface area.…”

“…combustion temperature, but which normally contain calcium, potassium and other trace elements such as phosphates [13,30,33]. No calcium, potassium or phosphate-containing crystalline phases were detected in these co-fired fly ashes, which may indicate that the quantity of crystalline phases potentially derived from the wood ash was too low to be detected by XRD.…”

“…12 ashes used in this study [13,14]. The co-fired fly ashes used in this study are primarily comprised of ash derived from the coal combustion with a much smaller quantity of ash derived from the secondary wood fuel source.…”

“…Furthermore, wood ash can have a much lower amorphous content than coal fly ash [13], which is a more important characteristic regarding the usefulness of co-fired fly ash as a precursor material given that wood ash is a component. Still, all three ashes have an amorphous hump at around 15-35° 2θ and centered around 25° 2θ.…”

“…A-FA-0 has mainly spherical particles, which is the characteristic morphology of the largely glassy fraction of coal fly ash. Biomass ash produced from pure wood combustion has a significantly different morphology compared to coal fly ash; it is mostly composed of fibrous particles with intact cell wall structures and high aspect ratios in addition to agglomerated fused woody particles [13]. In the B-CA-4 co-fired fly ash, an elongated particle can be seen intermixed with spherical particles that are more typically observed in coal fly ash.…”