METHOD OF PRODUCING STEEL WITH SPECIFIED LIMIT ON SULPHUR CONTENT Russian patent published in 2024 - IPC C21C5/28 C21C7/64 

FIELD: metallurgy.

SUBSTANCE: invention relates to ferrous metallurgy, particularly to production of steel grades with specified lower limit on sulphur content. Cast iron is devanadated by oxygen blowing and production of semi-finished metal, steel melting from semi-finished metal in oxygen converter, out-of-furnace treatment of liquid steel, vacuum treatment, modification of steel with calcium, purification blowing of steel, continuous casting of steel. Blowing of the metal product in the oxygen converter is performed with oxygen till carbon content is 0.05–0.30% lower than the lower limit of the specified grade content. Slag-forming mixture in the form of lime in amount of 300–700 kg/pl and silica-containing additives are added in the steel pouring course. During out-of-furnace treatment of liquid steel, thick and incompletely homogeneous slag is introduced using burnt lime and slag thinners in the form of fluorspar.

EFFECT: use of this technology provides guaranteed production of steel grades with specified lower limit on sulphur content, excluding production of melts with chemical composition that does not meet consumer requirements.

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