WANG Yunfei, SONG Shengqiang, LIU Hang, HUANG Ao, WEN Quhua
The chromium-containing refractory castables are widely utilized in high-temperature waste incineration gasification furnaces, ultra-high-temperature electric furnaces, and similar applications due to their exceptional performance characteristics. However, during service, these materials may produce toxic, carcinogenic hexavalent chromium (Cr(Ⅵ)), complicating the disposal of spent refractories and posing a serious environmental threat. Thus, the compositional design of these materials must consider both their service performance and the transformation of chromium phases to control Cr(Ⅵ) formation. Given the many deficiencies in the current oxide phase diagrams of chromium-containing castables, a new thermodynamic database was developed for chromium-containing oxides (WustCr). This chromium-specific database was successfully integrated into the thermodynamic calculation software FactSage and effectively utilized for conducting comprehensive phase diagram analyses in chromium-containing oxide systems. Using WustCr database, phase transformations and Cr(Ⅵ) formation in the ternary system Al2O3-CaO-Cr2O3, quaternary systems Al2O3-CaO-Cr2O3-Fe2O3, Al2O3-CaO-Cr2O3-MgO and Al2O3-CaO-Cr2O3-SiO2, as well as in chromium-containing castables for electric furnace lids were simulated. The calculation results were compared with experimental data, revealing a strong correlation, especially in predicting the evolutions of chromium phases and Cr(Ⅵ) formation. These findings demonstrate that the WustCr thermodynamic database serves as a starting point for thermodynamic modeling of the relevant phase diagrams, providing guidance for designing eco-friendly, high-performance chromium-containing refractory castables.