title: Quantitative, chemical, and mineralogical characterization of flue gas desulfurization by-products.
abstract: The objective of this study was to demonstrate that simple fractionation and selective dissolution techniques can be used to provide detailed chemical and mineralogical analyses of flue gas desulfurization by-products. The material studied was a mine grout prepared as a 1:1 mixture (wt./wt.) of fly ash (FA) and filter cake (FC) with hydrated lime (50 g kg(-1)) added to improve handling. The hydrated lime was composed mostly of calcite (CaCO3), portlandite [Ca(OH)2], lime (CaO), and brucite [Mg(OH)2] (515, 321, 55, and 35 g kg(-1), respectively) and had low (<6 g kg(-1)) concentrations of most trace elements. The FC contained hannebachite (CaSO3 x 0.5H2O) (786 g kg(-1)) with smaller quantities (<10 g kg(-1)) of calcite, quartz (SiO2), brucite, and gypsum (CaSO4 x 2H2O). Except for B and Cu, trace element concentrations were comparable to those in the hydrated lime. The FA contained both magnetic (222 g kg(-1)) and nonmagnetic (778 g kg(-1)) fractions. The former was composed mostly of hematite (Fe2O3), magnetite (Fe3O4), and glass (272, 293, and 287 g kg(-1), respectively), whereas the latter was enriched in glass, quartz, and mullite (Al6Si2O13) (515, 243, and 140 g kg(-1), respectively). Etching with 1% HF showed that 60 to 100% of trace elements were concentrated in the glass, although some metals (Co, Cr, and Mn) were clearly enriched in the magnetic phase. The aged grout contained 147 g kg(-1) ettringite [Ca6Al2(SO4)3(OH)12 x 26H2O] in addition to 314 g kg(-1) hannebachite and 537 g kg(-1) insoluble phases (mullite, quartz, hematite, magnetite, and glass).
authors.affiliation: CNRSSP, Douai, France. laperche@cnrssp.org
authors.forename: Valérie
authors.initials: V
authors.lastname: Laperche
authors.forename: Jerry M
authors.initials: JM
authors.lastname: Bigham
mesh_terms: D000393:Air Pollutants / Q000737:chemistry*; D005591:Chemical Fractionation; D005740:Gases / Q000737:chemistry; D006801:Humans; D017745:Incineration / Q000379:methods; D008903:Minerals / Q000032:analysis*; D012995:Solubility; D013458:Sulfur Dioxide / Q000737:chemistry*; D018505:Waste Management / Q000379:methods
chemical_list: D000393:Air Pollutants; D005740:Gases; D008903:Minerals; D013458:Sulfur Dioxide