PROCEDURE FOR MELTING AND DEGASSING RAIL STEEL Russian patent published in 2010 - IPC C21C7/00 

FIELD: metallurgy.

SUBSTANCE: procedure consists in melting metal in arc electric furnaces, in tapping steel from furnace and cutting furnace slag off, in adding slag forming mixture and ferroalloys into ladle, and in processing steel in aggregate "ladle-furnace" and in vacuum installation. During tapping from the furnace, steel in the ladle is blasted with nitrogen through porous tuyeres at consumption rate 0.004-0.014 m³/t and intensity 5-15 m³/h. Also lime at amount of 4-8 kg/per t of steel, silicon and manganese containing ferroalloys in terms of average contents in finished steel are added into the ladle. Further, steel is processed at the aggregate "ladle-furnace" to temperature 1600-1630°C. While processing, steel in the ladle is blasted with nitrogen through bottom porous tuyeres at consumption rate 8-20 m³/h, upon which it is treated in the vacuum installation of a chamber type at pressure below 0.3 torr. Steel is processed at continuous blasting with nitrogen with intensity 5-25 m³/h and consumption rate 0.01-0.30 m³/t through porous tuyeres and at total duration of treatment 15-60 minutes.

EFFECT: reduced expenditures and duration of steel processing at carbonic-nitride hardening, reduced concentration of oxygen in steel and level of steel impurity with non-metallic inclusions, upgraded mechanical properties of rails.