METHOD OF DESULPHURISING STEEL Russian patent published in 2017 - IPC C21C7/00 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy and can be used during off-furnace treatment of steel to produce steel with carbon content less than 0.05 wt%. Method involves steps of forming slag on molten steel, bringing vacuum above combination of slag and molten steel to a value less than 5 mm Hg, mixing molten steel and slag and deoxidation and desulphurization of molten steel and slag for degassing steel, reducing content of at least sulphur, nitrogen, oxygen and hydrogen and oxygen activity in molten metal to a value less than 30 ppm and formation of slag composition after degassing steel, wt%: CaO 50–70, SiO₂ 20–28, CaF₂ 5–15, MgO not more than 8, Al₂O₃ not more than 1, and a combination of FeO+MnO not more than 2, where total amount of CaO+CaF₂+SiO₂+MgO is at least 85 % by weight.

EFFECT: invention enables to avoid need for aluminium additives, reduces wear of refractory materials and increases efficiency of melting.

21 cl, 6 dwg