CO2 Capture via Carbonation of Steelmaking Slag in A High-gravity Rotating Packed Bed
Date Issued
2011
Date
2011
Author(s)
Pan, Shu-Yuan
Abstract
Carbon dioxide (CO2) sequestration using producing carbonates from steelmaking slags was performed in a rotating packed bed (RPB). The effects of reaction time, rotating speed, temperature, and slurry flow rate on the performance on the CO2 sequestration process were evaluated. One type of steelmaking slags provided by China Steel Company, namely basic oxygen furnace (BOF) slag, was selected as feedstock. The sequestration experiments were performed at a liquid-to-solid ratio of 20 mL/g with a flow rate of 2.5 L/min of a pure CO2 stream under atmospheric temperature and pressure. The carbonation products were analyzed quantitatively with thermogravimetric analysis (TGA) and atomic absorption spectrometer (AAS) and qualitatively with scanning electron microscope with energy dispersive X-ray spectroscope (SEM-EDX) and X-ray diffractometry (XRD). The results reveal that a maximum conversion of BOF slag was found to be 93.5% operated at a reaction time of 30 min and a rotating speed of 750 rpm at 65 ℃, 14.7 psig of CO2 partial pressure and a particle size of 63 μm. The major factors that affected the conversion were reaction time (1 min to 20 min), rotating speed (500 rpm to 1250 rpm), and temperature (25 oC to 65 oC). In addition, the experimental data also were utilized to determine the rate-limiting mechanism based on the shrinking core model (SCM) and the reaction kinetics based on the surface coverage model which could be validated by the observations of SEM-EDX and XRD. Furthermore, the carbon footprint of the developed technology in this investigation was calculated by a life cycle assessment (LCA). A comparison of the results with other studies suggests that accelerated carbonation in a RPB is viable due to its higher conversion, shorter reaction time, and relatively milder conditions.
Subjects
alkaline solid wastes
basic oxygen furnace slag
CO2 sequestration
calcium carbonate
shrinking core model
surface coverage model
life cycle assessment
Type
thesis
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