title: Multiple model approach to evaluation of accelerated carbonation for steelmaking slag in a slurry reactor.
abstract: Basic oxygen furnace slag (BOFS) exhibits highly alkaline properties due to its high calcium content, which is beneficial to carbonation reaction. In this study, accelerated carbonation of BOFS was evaluated under different reaction times, temperatures, and liquid-to-solid (L/S) ratios in a slurry reactor. CO2 mass balance within the slurry reactor was carried out to validate the technical feasibility of fixing gaseous CO2 into solid precipitates. After that, a multiple model approach, i.e., theoretical kinetics and empirical surface model, for carbonation reaction was presented to determine the maximal carbonation conversion of BOFS in a slurry reactor. On one hand, the reaction kinetics of BOFS carbonation was evaluated by the shrinking core model (SCM). Calcite (CaCO3) was identified as a reaction product through the scanning electronic microscopy and X-ray diffraction analyses, which provided the rationale of applying the SCM in this study. The rate-limiting step of carbonation was found to be ash-diffusion controlled, and the effective diffusivity for carbonation of BOFS in a slurry reactor were determined accordingly. On the other hand, the carbonation conversion of BOFS was predicted by the response surface methodology (RSM) via a nonlinear mathematical programming. According to the experimental data, the highest carbonation conversion of BOFS achieved was 57% under an L/S ratio of 20 mL g(-1), a CO2 flow rate of 0.1 L min(-1), and a pressure of 101.3 kPa at 50 °C for 120 min. Furthermore, the applications and limitations of SCM and RSM were examined and exemplified by the carbonation of steelmaking slags.
authors.affiliation: Graduate Institute of Environmental Engineering, National Taiwan University, Taiwan, ROC. Electronic address: d00541004@ntu.edu.tw.
authors.forename: Shu-Yuan
authors.initials: SY
authors.lastname: Pan
authors.affiliation: Graduate Institute of Environmental Engineering, National Taiwan University, Taiwan, ROC. Electronic address: r98541126@ntu.edu.tw.
authors.forename: Hsing-Lu
authors.initials: HL
authors.lastname: Liu
authors.affiliation: Department of Biochemistry, Taipei Medical University, Taiwan, ROC. Electronic address: eechang@tmu.edu.tw.
authors.forename: E-E
authors.initials: EE
authors.lastname: Chang
authors.affiliation: Department of Energy and Environmental System Engineering, University of Seoul, South Korea. Electronic address: h_kim@uos.ac.kr.
authors.forename: Hyunook
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, Taiwan, ROC. Electronic address: yhchen1@ntut.edu.tw.
authors.forename: Yi-Hung
authors.initials: YH
authors.lastname: Chen
authors.affiliation: Graduate Institute of Environmental Engineering, National Taiwan University, Taiwan, ROC; Carbon Cycle Research Center, National Taiwan University, Taiwan, ROC. Electronic address: pcchiang@ntu.edu.tw.
authors.forename: Pen-Chi
authors.initials: PC
authors.lastname: Chiang
mesh_terms: D002119:Calcium Carbonate / Q000737:chemistry; D002245:Carbon Dioxide / Q000737:chemistry*; D007220:Industrial Waste / Q000032:analysis; D007700:Kinetics; D008956:Models, Chemical; D010100:Oxygen / Q000737:chemistry; D013232:Steel / Q000737:chemistry*; D013696:Temperature
chemical_list: D007220:Industrial Waste; D013232:Steel; D002245:Carbon Dioxide; D002119:Calcium Carbonate; D010100:Oxygen
keywords: CO(2); Effective diffusivity; Mineralization; Nonlinear mathematical programming; Response surface methodology; Shrinking core model