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The aim of the work is a theoretical and experimental study of the behavior of oxygen, hydrogen and nitrogen in iron during desulfurization with its granulated magnesium. A computational and analytical assessment of the formation and floating of gas bubbles during the introduction of dispersed magnesium into a metal melt in an argon jet is performed. It has been established by calculation that when dispersed magnesium is introduced into the cast iron in an argon jet, through a lance with a nozzle diameter of 7 mm to a depth of 3 m, argon bubbles with a diameter of 25 mm are formed. The thermodynamic probability of the processes of interaction of magnesium with oxygen, nitrogen and hydrogen during desulfurization of cast iron has been established. It has been established that the processes of desulfurization and deoxidation of iron occur throughout the entire range of pressures under study, and the formation of magnesium nitride is possible only with an excess pressure in the gas-metal system at a depth of molten iron more than 1.4 meters. Experiments in industrial conditions revealed the features of the removal of oxygen, nitrogen and hydrogen from cast iron during desulfurization of the melt with dispersed magnesium in a stream of various carrier gases. It was established experimentally that the type of carrier gas has a decisive influence on the by-pass degassing of the iron during its desulfurization by injecting granular magnesium. When using nitrogen or argon as a carrier gas, the hydrogen content in cast iron is reduced by 50-70%.

This phenomenon is undesirable, as it is accompanied by a sharp decrease in the active surface of the introduced reagent. In the case of mono-injection of magnesium, it is necessary to ensure a granular composition of the reagent and a high (more than 50 m/s) flow rate into the molten iron. When granular reagents with particle diameters of more than 0.4 mm are blown in, the velocity parameter is decisive, since it provides the possibility of introducing reagent particles into the hot metal to a depth of up to 20-25 mm. In accordance with the recommended parameters for the injection of granular magnesium in most hot metal treatments, the magnesium content in cast iron after refining exceeds the equilibrium values of the equilibrium system [Mg]-[S]. The latter provides stability and reliability of the process of hot metal desulfurization by mono-injection of granular magnesium. The degree of desulfurization is up to 95-99 %. Theoretical provisions are confirmed experimentally.

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