The speciation of elements in incinerator residues and their stabilized products

The speciation and solid phase-association of elements in combustion residues has implications for the leachability of residues, the solidification/stabilization (s/s) of residues, and the utilization of residues. In this paper, the authors use a variety of fractionation techniques, bulk analysis and surface microanalysis techniques, and geochemical modeling of leaching of residues to ascertain residue mineralogy, elemental speciation and bonding, and solid phase dissolution. The residues under investigation are a hazardous waste bottom ash (HWBA) and hazardous waste dry lime scrubber residue (HWSR) from a U.S. rotary kiln hazardous waste incinerator; MSW bottom ash (USBA) and MSW dry lime scrubber residue (USSR) from a U.S. mass burn combustor; and MSW ESP ash (CESP) and MSW dry lime scrubber residue (CSR) from a Canadian mass burn combustor. The residues are size reduced (< 300 um) and characterized for total composition using NAA. Fractionation schemes employing magnetic separation (gross and isodynamic separation), density gradient separation (1, 1, 2, 2-tetrabromoethane, < 2.95 g/cm3 or > 2.05 g/cm3), and acid etching are used to concentrate phases into various fractions. Specimens are analyzed in powder form, petrographic 30 μm thin sections, or thin foils