Understanding the slag composition-structure-property relationship remains challenging due to the
amorphous nature of slag melts and the difficulty of high-temperature experimental investigations.
Since the CaO-Al2O3-SiO2 slag system is maybe the most important slag system for various hightemperature
metallurgical process, the present research employed high-throughput molecular
dynamics (MD) simulations on the entire composition region of the CaO-Al2O3-SiO2 slag system to
determine physical properties like molar volume, density and diffusivity, structural properties such
as distribution of different oxygen types for each simulated slag melt. The obtained slag properties
result from the simulations displayed good consistency with experimental data, underscoring the
reliability of the MD simulation as a novel tool to predict reasonable slag properties and to study slag
behaviour from atomistic insight. The simulated results demonstrate a near-linear relationship
between molar volume changes and composition, highlighting the predominant role of oxygen
atoms, which is attributed to the significantly larger size of oxygen compared to other cations in the
slag melts. This disparity in size leads to oxygen ions occupying most of the space in slags, thereby
playing a major role in determining the overall molar volume. The simulation results of slag density
revealed a decreasing trend with increased SiO2 content and identified a local minimum at constant
SiO2 when Al2O3 content increases, also consistent with established slag density models.
Furthermore, the simulated oxygen self-diffusion coefficients reveal a strong composition-structureproperty
relationship, where an increase in CaO content enhances slag diffusivity, while a minimum
in diffusivity is observed near a CaO/Al2O3 ratio of unity. The diffusivity minimum also corresponding
to the local viscosity maxima, indicating effective simulation of charge compensation effects and
dynamic characteristics of slag melts. The simulated distribution of oxygen types in slag — bridging
oxygen (BOs), non-bridging oxygen (NBOs), free oxygen (FOs) and tricluster oxygen (TOs) —
reveals a composition-dependent pattern: BOs peak near CaO/Al2O3 = 1, NBOs and FOs are
abundant in CaO-rich areas with NBOs peaking near the Ca3SiO5 composition, FOs in the CaO
corner, and TOs predominantly in the Al2O3 corner, highlighting the complex interplay of network
formers and modifiers for the charge compensation effects on the slag’s structural properties. The
successful application of MD simulations in this study paves the way for a powerful approach to
explore the complex relationships in multicomponent slag systems and bridges the gap between
mathematics modelling and experimental observations in high-temperature metallurgical processes.