생활폐기물 소각시설 비산재의 안정화 전후의 XRF 및 XRD 분석 특성

Abstract

Ministry of Environment has regulated fly ash from municipal solid waste (MSW) incineration plant as a designated waste by Waste Management Act because of its hazardous components such as heavy metals and dioxins. By this reason, fly ash has been stabilized using either metallic or chemical agents prior to final land disposal. In this study, fly ash was stabilized using chemical agents and portland cement in order to know the compositional and characteristic variation of heavy metals in fly ash before and after stabilization. Raw and stabilized fly ashes were analyzed by X-ray fluorescence spectrometer (XRF), X-ray diffractometer (XRD). The results were summarized as follows. Mass spectrometer's result showed that the major components in stabilizing agents was methyl N-dimethyl thiocarbamate (C4H49ONS), dimethyl carbamodithioic acid (C3H6NS2) and tetramethyl thiourea (C5H12N2S). Also, XRD's result showed that raw fly ash largely contained CaClOH, Ca(OH)2 and CaCO3, which were considered to be resulted from the spray of lime for controlling acidic pollutants at spray dryer absorber (SDA). When adding 2% to 5% (w/w) of chemical agents into fly ashes there were almost no compositional variations of heavy-metal components in stabilized fly ashes, but the compositional percentiles of Na2O and SiO2 were somewhat decreasing while that of CaO was slightly increasing. When adding 5% of chemical agents and 10% to 30% (w/w) of portland cement into fly ashes, the compositional percentiles of SiO2, Al2O3, CaO and SO3 were considerably increased while those of Na2O, Cl, K2O were relatively decreased. Accordingly, the basicity (CaO/SiO2) of stabilized fly ashes were decreased to a level of 7.53±12.57 from 16.35 of raw fly ash. Key words : Fly Ash, MSW, Incineration Plant, XRF, XRD, Stabilizing Agent