Thermodynamic assessment of the phase diagrams of calcite and CaO–CaCO3 system

Abstract

The study of phase equilibria in the Ca–C–O system is complicated by the decomposition of one of the intermediate compounds, calcite. Experimental studies present an ambiguous interpretation of the results, which contain conflicting information about the phase diagrams of calcite and the CaO–CaCO3 system at pressures up to 100 MPa. Thermodynamic modelling has been used in this study for the determination of phase equilibria in these systems. Using reliable experimental phase diagram data, the thermodynamic properties of calcite and CaCO3(liq) were corrected to take into account the pressure influence. This resulted in an accurate reproduction of the experimental data on calcite phase equilibria and made it possible to construct a model of the CaO–CaCO3 system phase diagram taking into account the calcite decomposition. It will allow to further modelling of more complex processes involving calcite in the pressures range up to 30 MPa and temperatures up to 1800 K.