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The phase diagrams of FeO–SiO2–V2O3 systems as the main components of vanadium slag are assessed on the basis of the existing literature models and experimental studies to modify partial parameters by FactSage thermodynamic software. The results show that the eutectic and peritectic reactions for the FeO–V2O3 system happen at about 1626 and 1985 K, respectively. The eutectic and monotectic reactions for the V2O3–SiO2 system happen at about 1935 and 1963 K, respectively. According to the actual blowing temperature of the vanadium‐extraction converter, the isothermal section at 1573, 1623, and 1672 K of the FeO–SiO2–V2O3 ternary system is calculated, and the isothermal section at 1573 and 1623 K has seven phase regions, which are the liquid + spinel + tridymite, liquid + wustite + spinel, spinel + tridymite + karelianite, liquid + tridymite, liquid + spinel, liquid + wustite, and liquid, respectively. But liquid + wustite and liquid + wustite + spinel regions disappear at 1673 K. Meanwhile, two ternary eutectic points are determined to be at 1470 and 1476 K, respectively. Peritectic reaction of phase wustite, karelianite, and silica (tridymite and cristobalite) occurs at 1702 and 1750 K, respectively.

In BOF steelmaking process, high-activity lime has been widely used to form an appropriate slag as a medium for the removal of non-volatile impurities from the hot metal treated. In recent years, however, great attention has been paid to the possibility of directly using limestone instead of lime in the furnace. Despite laboratory experiments and industrial trials have proven the feasibility of the technique, a list of underlying issues still require more considerations, e.g., thermodynamics and kinetics of steelmaking reactions and limestone evolution during blowing under the new condition. The main motivation behind this paper is to establish a kinetic model for limestone decomposition under BOF steelmaking condition on the basis of shrinking core hypothesis. The Kozeny-Carman equation that correlates pressure gradient with the corresponding velocity is integrated into the model in order to account for the CO 2 flow through the lime layer packed with small grains. The model is demonstrated using a set of experimental data and is finally verified by comparing the obtained thermal conductivity and grain size with available values in the literature.

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