Interregional Public Organization "Association of Steel Smelters" (Moscow, Russia):

G. N. Elansky, Dr. Eng., Prof., e-mail: elanskiy37@mail.ru

Steel Institute of the Union of German Metallurgists (Düsseldorf, Germany):
D. Ameling, Dr. Eng., Prof., e-mail: mud.ameling@t-online.de

National University of Science and Technology “MISiS” (Moscow, Russia):
D. G. Elansky, Cand. Eng., Associate Prof., e-mail: de-misis@inbox.ru
G. I. Kotelnikov, Cand. Eng., Associate Prof., e-mail: gikotelnikov@yandex.ru

The defi nition of the oxidation degree of elements is given, the calculation of the average oxidation degree of iron in the simultaneous presence of FeO and Fe₂O₃ is shown. Oxidation state and iron participation in redox processes are considered. Iron can have oxidation states ranging from zero (pure iron) to +8. The most important are oxidation states 0, +2 and +3. The structure of molten slag is considered. It can simultaneously contain products of dissociation of molecular components in the form of cations and anions, non-dissociated molecules and complex associations of molecules or cations with anions (clusters, complexes, associates). Iron is a major contributor to oxygen transport in steelmaking processes. Under the infl uence of oxygen, iron is oxidized to FeO and Fe₂O₃, forming a Fe⁺² cation and FeO₂^–1 anion in the slag. Аverage oxidation number of iron in ores, concentrates, wustite, in the slag of equilibrium distribution processes of phosphorus between molten iron and slags, in the slag of open-hearth furnace basic and acidic processes, in the slag BOF and EAF processes are calculated. Аverage gross formula of the iron oxide in the slag FeO_х, where 0 < x ≤ 1,5 is proposed. The average oxidation number of iron in equilibrium state of distribution of phosphorus between the molten iron and slag is equal to (of 2.03 to 2.47), in exfoliated slags of quaternary system CaO – FeO_n – P₂O₅ – SiO₂ — (2.11–2.37), and in system CaO – FeOn – P₂O₅ – MgO – M_nO_n — (2.12–2.41); in homogenous slag systems in average — (2.20 – of 2.27). The average degree of oxidation of iron in slag depends on the partial pressure of oxygen and slag composition and does not depend on the concentration of iron oxide.
The authors are grateful to Prof. Dr. Klaus Koch (01.09.1936–20.05.2019, Institute of Metallurgy of the Technical University of Clausthal, Germany), Dr. Eng. L. Ya. Levkov (NPO TsNIITMASH), Dr. Eng., Prof. A. A. Kozhukhov (Stary Oskol Technological Institute) and Dr. Eng., Associate Prof. S. P Burmasov (Ural Federal University named after the first President of Russia B. N. Yeltsin) for the source materials and fruitful discussion.

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