Abstract:

The transport of oxygen through slag can greatly affect different metallurgical processes such as desulfurization, dephosphorization, and electroslag remelting where efficient mass transfer is essential for impurity removal. Oxygen transport is strongly influenced by both ionic and electronic conductivity of the slag, but many studies have overlooked this by describing oxygen transport in terms of diffusion of reducible oxides such as FeO. Although this approach generally works in narrow composition ranges, it does not fully account for all important factors.

In this work, an experimental study was carried out on oxygen transport in Fe₂O₃–CaO–SiO₂ slags, focusing on the effects of basicity, iron oxide content, and temperature. During each experiment, molten slag was exposed to a controlled CO₂-CO atmosphere. After quenching, samples were sectioned, and the Fe³⁺/Feₜ ratio was measured by titration at different depths to capture the composition profile. The resulting data was then analyzed using a model that considers the combined influence of ionic and electronic conductivity. For each parameter, the resulting changes in the conductivities were used to understand how they influence the overall oxygen transport and to identify which type of conductivity dominates under different conditions.

The agreement between the experiments and the model provides further confirmation of the validity and applicability of the proposed transport framework.

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Mr. Parsa Khanmohammadi Hazaveh