Slags play an important role in melting processes (dephosphorization,
desulfurization and deoxidation) and during tapping of steel in the ladle. During
melting of steel in basic EAF, the slags change the chemical composition in each melt.
These aspects govern the quality of molten steel for castings and in consequence – the
properties of each grade of cast steel. The structure of multicomponent systems, the
structure of slags according to molecular or ionic theories, composition of slags during
oxidation and reduction periods of melting and calculation of their basicity are shown.
Keywords: Basicity of slags, EAF slags, Multicomponent systems, Slag
properties, Synthetic slags.