Abstract
To develop highly efficient hydrated lime for the treatment of flue gas from the municipal waste incineration plants, the authors employed the hydrated lime production process in which water was used for slaking quicklime. Then, we prepared the hydrated lime by slaking quicklime with water of 0.65 to 10 times the mass of quicklime and investigated the relation between pore structure characteristics and dry SO2 adsorption capacity. The mass ratio of water to quicklime was termed SWR (slaking water ratio). From the results, the hydrated lime obtained by slaking with SWR = 0.9 possessed the highest pore volume and SO2 adsorptivity. The hydrated lime prepared by slaking with SWR lesser or larger than 0.9 showed lower pore volume and SO2 adsorptivity.
Based on the average crystallite size of the hydrated lime calculated from the half-width of characteristic XRD peak, it was found that the crystallite size increased with SWR and that the pore volume increased with the crystallite size and reached a maximum at 35 nm and then decreased with the increase in crystallite size. To explain this finding, the pore volume was estimated by a simple model using the crystallite size obtained. As the result, it was found that the calculated pore volume was in good agreement with the pore volume measured by N2 adsorption/desorption method.
