fugacity and chemical conditions for our feed materials. Perple_X enables construction of phase diagrams (P-T, T-Log fO2, chemistry, etc.) for multi-component systems by minimizing Gibbs free energy for given bulk compositions. Direct H2 reduction experiments are currently being conducted to evaluate the phase transformation and metal recovery potential of the BR. The tests are performed using 4 g of BR per experiment at temperatures ranging from 700 to 1100 °C, with treatment durations between 15 and 180 minutes. A controlled gas flow of 100 to 500 L/h is applied using a gas mixture consisting of 10 vol.% hydrogen balanced with nitrogen, under atmospheric pressure. These conditions are designed to systematically assess the influence of temperature, residence time, and gas flow rate on reduction kinetics, phase evolution, and the formation of recoverable iron- and titanium-bearing phases. After reduction, the phases present were identified by X-ray diffraction (XRD). The experimentally observed phase assemblages and recoveries were compared against the model predictions. This validation step was crucial to confirm that the thermodynamic models captured the essential chemistry of the real system, and to calibrate any differences (for instance, due to kinetic effects or minor components not in the model). XRF analyses of the BR sample were utilised for setting up the calculations. Major oxide components (Al₂O₃, SiO₂, Fe₂O₃/FeO, TiO₂, CaO, Na₂O, etc.). The pseudosection has been calculated using Perple_X_7.1.13 (Connolly, 2009) in the system NCFMASHTO. We used the internally consistent thermodynamic database of Holland and Powell (1998, revised version of 2002) and the following solid solution models: Ppv(stx8), O(stx8), FeSi(BCC), Opx(stx8), Neph(FB), Cpx(stx8), Pl(stx8), Kf, Gt(stx8), Crd(HGP), Sapp(HP), Sp(stx8), Mt(W), Ilm(WPH), Wus, Fper(H), Cor(H), ZrRu. The CORK equation of state for H2O-CO2 fluids (Holland & Powell, 1998) was used, although fluids have been considered pure H2O. The pressure was fixed at 1 bar for simulating atmospheric and furnace conditions (a reasonable approximation for open reactors). Oxygen fugacity (Log fO₂) was adjusted to represent different redox conditions (-29 to -5). PyWerami, a visualization and analysis tool for the Perple_X software package, was used to extract and display the stability fields and modal abundances of individual mineral phases from the calculated thermodynamic datasets. The thermodynamic modelling was performed using a publicly available dataset originally developed for metamorphic and geological systems. While this dataset provides a robust framework for evaluating phase stability trends, it is not specifically optimized for highly alkaline industrial environments, hydrogen-rich atmospheres, or synthetic phases commonly encountered in cementitious and metallurgical systems, such as larnite or gehlenite. Therefore, the results are interpreted as indicative stability trends rather than
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