Characterization and alternative use study of fly ash

Adeoti, Ibraheem Adetunji (2011) Characterization and alternative use study of fly ash. Masters thesis, Memorial University of Newfoundland.

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Abstract

In the generation of power from fossil fuels and biomass, fly ash (FA) is produced and represents both an environmental and economic cost with respect to disposal. However, it also represents a re-use opportunity. Increasing solid waste disposal costs and a focus on sustainable processing necessitates research in alternative uses for fly ash. In this thesis, two ash samples, hog-boiler precipitate ash sample (HBP) and mixed ash pond sample (MAP) from the AV-cell pulp and paper plant were examined for their chemical, physical, thermal, and mineralogical properties. Other physio-chemical properties like density, pH and buffering power were also determined. -- Characterization results were used to determine and test alternative uses for FA. Result shows that the samples are rich source of alum inosilicate, SiO₂, CaO, and Al₂O₃ which are feedstock for adsorption and zeolite synthesis. The concentration of SiO₂ to Al₂O₃ is greater than 1.5 therefore indicating good potential for zeolite synthesis. The FAs pH was between 10.0 and 13.0 with buffering power ranges from 0.5 to 4.9 mmol/pH, as such, were tested for acid mine drainage (AMD) neutralization. Treated effluent water final pH was between 9.0 and 12.2 with contaminant removal efficiency of 85%. Neutralization residue was treated hydrothermally and resulted in an increased adsorption properties zeolite, tested for AMD treatment and yielded above 90% contaminant removal efficiency. The total chemical species (SiO₂ + Al₂O₃ + CaCO₃ + CaO + Na₂O + K₂O + MgO Fe₂O₃) is greater than 90 wt.% hence, the FAs were tested for permeable reactive barriers (PRB) application and its contaminant removal efficiency was also greater than 90% with final treated effluent water pH ranges between 8.4 and 12.2. -- Overall, AMD treatment with FA provides a low cost, environmentally safe and beneficial use of what would be considered a waste.

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