Abstract The interaction between fayalitic slags and nonferrous metals during smelting presents a multifaceted challenge that necessitates comprehensive investigation to enhance metallurgical processes toward the recovery of valuable metals. This study builds on the literature review of the composition and mineralogy of fayalitic slags (Part I), examining the effect of these composition on thermodynamic and physical properties, which were generated through thermochemical simulations using available databases and known studies. The findings and models created have shown that small changes in composition have significant effects on properties. For each property studied an equation was derived from the model to summarize and simplify complex calculations. Differences between predicted values and experimental results were also commented. Melting temperature, for example, increases mainly with the CaO content increase, reaching up to 1600 °C. On the other hand, SiO 2 content increase plays a more significant role in the increase of viscosity, where values of up to 3 Pa·s were observed. Meanwhile, the FeO content increase has shown significant effect on density, up to 3.4 g·cm −3 . The addition of secondary compounds (fluxes) such as Al 2 O 3 , MgO, and Fe 2 O 3 have also influenced the melting temperature, viscosity, and density of fayalitic slags, with 9 mass% Al 2 O 3 notably expanding the low-viscosity area between 0.1 and 1 Pa·s and altering density ranges, while Fe 2 O 3 effectively reduces viscosity more than CaO. The combination of these compounds further modify the properties, enhancing the potential for targeted mineral enrichment in fayalitic slags. The study demonstrates how slag composition adjustments can lower melting temperatures and viscosity, while reducing the heat input and energy needs. Regression models enable efficient fayalitic slags designs aligned with sustainable goals, thereby reducing overall carbon footprint, facilitating slag reprocessing for metal extraction, minimizing waste, and environmental impact. Graphical Abstract
Weiss et al. (Mon,) studied this question.