Effect of Mineral Compositions on Volatilization of Pb during Coal Combustion

抄録

Coal-fired power plants are the main sources of atmospheric Pb. The mineral composition of coal is an important factor of the trace element distribution. The Pb volatilization characteristics of the anthracite, lignite and bitumite were examined in the horizontal tube furnace. SiO₂, Al₂O₃, CaO and Fe₂O₃ were chosen as the mineral compositions and PbO was chosen as Pb source to investigate the effect of minerals on Pb volatilization during coal combustion. The results indicated that the occurrence modes of Pb and mineral composition were major factors in Pb volatilization and the coal containing more silicon and aluminum had the lower Pb volatilization rate. The intrinsic minerals in coal immobilized the released Pb through both physisorption and chemisorption. The combustion and thermogravimetric investigation showed that the Pb capture efficiency of the four minerals ranked as SiO₂>Al₂O₃>CaO>Fe₂O₃. The formation of the non-volatile materials such as PbSiO₃, Ca₂PbO₄ and PbFe₁₂O₁₉ accounted for the capture mechanisms of SiO₂, CaO and Fe₂O₃, while Al₂O₃ stabilized Pb via the physisorption. The synergy of SiO₂ and Al₂O₃ exhibited the most superior capture efficiency on Pb, which provided references to the preparation of oriented Pb removal adsorbent.