89Coal Combustion Waste Materials
reacting with Al
3+
, thus removing it from the soil solution and greatly reducing its
toxic effects (Shainberg et al., 1989; Smyth and Cravo, 1992).
3.2.3 Dry fgD
Dry scrubbing is a process where an atomized alkaline sorbent (lime or soda ash)
slurry is mixed concurrently with ue gas and reacted in an absorber, thus the name
spray dryer absorber (SDA). Sorbent droplets react with SO
2
in the ue gas and
the desulfurized gas, along with reaction products and unreacted sorbent, exit the
absorber where they are collected in a baghouse. Dry scrubbers can be used on
ue gas prior to y ash collection, so the existing particulate collection system can
often be used to collect y ash and absorber products. A specic ...