| dc.description.abstract | This study investigated the sintering characteristics of sewage sludge incinerator ash (SSIA) for porous lightweight aggregates, by heating the SSIA (from two different-processed sewage plants) under controlled conditions of varifying temperature (1050-1150℃), time (10-30 min.), and sludge ash components (SiO2, Al2O3, and flux). SEM and XRD techniques were used to examine the thermal treatment properties, including the bloating mechanism, microstructure, and speciation variation.
The tested raw SSIA has considerably low contents and TCLP leaching concentrations for Pb, Zn, Cu, and Cr, all meeting the regulatory thresholds. The results indicate that the SSIA bloated well within 1060-1090℃, mainly characterized by its components, heating temperature and time. Properly controlled conditions could produce aggregates that meet CNS for common and lightweight standards. A lightweight density as low as 1.6 g/cm3 can be obtained.
With respect to the modification of SSIA compositions, it was found that the addition of cullet increased the SiO2 content, lowering the melting point, and further the bloating temperature of the ISSA.
On the other hand, the addition of Al2O3 delayed the bloating time but strengthened the compressive strength of the resultant aggregates.
Moreover, the addition of small amount (5%) of MSW incinerator fly ash could lower the bloating temperature, whereas excess amount resulted in a slow but increasing bloating temperature, suggesting the interaction between the flux species in the ISSA. | en_US |