| Summary: | 碩士 === 長庚大學 === 化工與材料工程學系 === 99 === Limestones (105 μm ~ 149 μm) from 7 different resources were calcined at 800 oC for 5 hours. The limes were sulfated at 850 oC for six hours in tubular reactor under the gases of the composition of 1% SO2、 9.6% CO2、 10.08% O2、 79.32% N2. The physical and chemical characteristics of the limes before and after the sulfation reaction were studied.
Experimental results show that the parts of the reactor calcined limestones were carbonated in the sulfation due to the presence of carbon dioxide. Because the molar volumes of calcium carbonates and calcium sulfates are larger than that of calcium oxides, the produced calcium carbonates and calcium sulfates crystals blocked the pores of calcium oxide during sulfation reaction. H, L and G limes with the largest specific surface areas and pore volumes carbonated more easily than other limes. Although T limes have the specific surface area and pore volume larger than these of G2, U and M limes, the carbonation reaction was not noticed. This is because T limes have the richest micropores, the formed calcium carbonates were easily decomposed at the micropores.
From the FE-SEM images, H, L and G limes the generation of calcium sulfate crystals was not obvious. On the contrary, the calcium sulfate crystals on T limes surface were easily observed. The results indicate that H, L and G limes prefer being carbonated than being sulfated, which T limes prefer being sulfated than being carbonated.
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