Experimental Study on the Thermodynamics of the CaO-SiO2-Ce2O3 System at 1873 K
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The phase relations in the CaO-SiO2-Ce2O3 system under the reducing atmosphere at 1873 K were determined by the conventional equilibrium and quenching method combined with scanning electron microscopy-electron probe microanalysis (SEM-EPMA) and X-ray diffraction (XRD) measurements on the quenched samples. Based on these analyses, a large part of the isothermal phase diagram was constructed. Furthermore, the thermodynamic activities of Ce2O3 in the melts at 1873 K were measured by the chemical equilibrium method. Using the measured activity data, an empirical formula to estimate the activity coefficient of Ce2O3 was proposed based on the regular solution model. It was found that, for the melts with the same Ce2O3 contents, the thermodynamic activities of Ce2O3 increase gradually with the rise of basicity (the ratio of CaO to SiO2) of the melts. This implies that, from the thermodynamic point of view, the increase of basicity is favorable to the enrichment and precipitation of Ce-containing mineral phases.
The financial support of Projects 51464040, 51534001, and 51774025 from the National Natural Science Foundation of China and the open project for key basic research of the Inner Mongolia Autonomous Region (20140201) is gratefully acknowledged.
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