Particulate matter emission during MSW/RDF/WW combustion: Inorganic minerals distribution, transformation and agglomeration

In this study, experimental results on size distribution, inorganic element distribution, and inorganic minerals composition/transformation of particulate matter generated from solid waste combustion are revealed. The results showed that the PM10 generated from solid waste combustion exhibited a trimodal distribution. The yields of PM1 and PM10 shows a linear correlation with the (Na2O + K2O)/(SiO2 + Al2O3) ratio of solid waste ash. As the ratio of (Na2O + K2O)/(SiO2 + Al2O3) increases, the yields of PM1 and the proportion of PM1/PM10 increases. Among all solid wastes, the migration tendency of Si to PM10 is the smallest. The K in MSW and RDF has the highest migration tendency to PM10, and the migration tendency of heavy metal elements (Fe, Mg) in WW to PM10 was higher than that of alkali elements. The PM2.5–10 generated from MSW combustion were composed of a molten inorganic salt components (Na/K/Mg-Al-Si, Na/K/Ca-Cl and Na/K-S-O) and refractory spherical/irregular mineral components (Ca-Al-Si, Fe2O3, SiO2, Ca-Si, etc.). The difference in the relative content of CaO, SiO2, and Al2O3 in the solid waste ash led to different existence forms of Ca-Al-Si species in the ash particles generated during combustion. The agglomeration and coalescence mechanism of refractory coarse particles in PM10 were also revealed.