Kinetics of ${\text{SO}}_2$ Absorption with Fly Ash Slurry with Concomitant Production of a Useful Wastewater Coagulant

This research was aimed at recovering Fe and Al compounds to produce a useful complex coagulant from fly ash using ${\text{H}}_2{\text{SO}}_4$ and ${\text{SO}}_2$ from flue gas oxidized to ${\text{SO}}_3$ by ${\text{NaClO}}_3$ . The reaction kinetics of wet ${\text{SO}}_2$ scrubbing from simulated flue gas with fly ash slurry was studied. The ${\text{SO}}_2$ scrubbing experiments were carried out in a jacketed glass reactor system with a simulated flue gas containing ${\text{SO}}_2$ and ${\text{N}}_2$ in the gas phase and fly ash slurry in the liquid phase. Sodium chlorate was added to oxidize ${\text{SO}}_2$ to ${\text{SO}}_3$ , adding ${\text{H}}_2{\text{SO}}_4$ in the slurry. The reaction orders of both ${\text{Fe}}_2{\text{O}}_3$ and ${\text{Al}}_2{\text{O}}_3$ extraction from fly ash slurry were shown to be 1.5. The empirical Arrhenius expressions were also derived from the reaction rate constants obtained at each reaction temperature. The mass transfer process of ${\text{SO}}_2$ with ${\text{ClO}}_3^{-}$ was evaluated using a two-film theory model.