Rhombohedral calcite precipitation from CO2-H2O-Ca(OH)2 slurry under supercritical and gas CO2 media
2007
Montes-Hernandez, German | Renard, François | Geoffroy, Nicolas | Charlet, Laurent | Pironon, Jacques | Laboratoire de Géophysique Interne et Tectonophysique (LGIT) ; Observatoire des Sciences de l'Univers de Grenoble (OSUG) ; Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS) | Physics of Geological Processes [Oslo] (PGP) ; Department of Physics [Oslo] ; Faculty of Mathematics and Natural Sciences [Oslo] ; University of Oslo (UiO)-University of Oslo (UiO)-Faculty of Mathematics and Natural Sciences [Oslo] ; University of Oslo (UiO)-University of Oslo (UiO)-Department of Geosciences [Oslo] ; Faculty of Mathematics and Natural Sciences [Oslo] ; University of Oslo (UiO)-University of Oslo (UiO) | Géologie et gestion des ressources minérales et énergétiques (G2R) ; Université Henri Poincaré - Nancy 1 (UHP)-Institut National Polytechnique de Lorraine (INPL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Centre National de la Recherche Scientifique (CNRS) | ANR Géocarbone - Carbonatation
International audience
显示更多 [+] 显示较少 [-]英语. The formation of solid calcium carbonate (CaCO3) from aqueous solutions or slurries containing calcium and carbon dioxide (CO2) is a complex process of considerable importance in the ecological, geochemical and biological areas. Moreover, the demand for powdered CaCO3 has increased considerably recently in various fields of industry. The aim of this study was therefore to synthesize fine particles of calcite with controlled morphology by hydrothermal carbonation of calcium hydroxide at high CO2 pressure (initial PCO2=55 bar) and at moderate and high temperature (30 and 90°C). The morphology of precipitated particles was identified by transmission electron microscopy (TEM/EDS) and scanning electron microscopy (SEM/EDS). In addition, an X-ray diffraction analysis was performed to investigate the carbonation efficiency and purity of the solid product. Carbonation of dispersed calcium hydroxide ( ) in the presence of supercritical (PT=90 bar, T=90°C) or gaseous (PT=55 bar, T=30°C) CO2 led to the precipitation of sub-micrometric isolated particles (<1µm) and micrometric agglomerates (<5µm) of calcite. For this study, the carbonation efficiency (Ca(OH)2-CaCO3 conversion) was not significantly affected by PT conditions after 24 h of reaction. In contrast, the initial rate of calcium carbonate precipitation increased from 4.3 mol/h in the "90bar-90°C" system to 15.9 mol/h in the "55bar-30°C" system. The use of high CO2 pressure may therefore be desirable for increasing the production rate of CaCO3, carbonation efficiency and purity, to approximately 48 kg/m3h, 95% and 96.3%, respectively in this study. The dissipated heat for this exothermic reaction was estimated by calorimetry to be -32 kJ/mol in the "90bar-90°C" system and -42 kJ/mol in the "55bar-30°C" system.
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