PROCEDURE FOR REFINING RAIL STEEL IN LADLE-FURNACE Russian patent published in 2011 - IPC C21C7/00 

FIELD: metallurgy.

SUBSTANCE: procedure consists in metal arc heating, in flushing melt with inert gas through porous bottom tuyeres and in treatment of metal with slag in aggregate furnace-ladle and vacuumiser. Metal is arc heated in the aggregate ladle-furnace to temperature 1600-1630°C with blowing with nitrogen through porous bottom tuyeres at flow rate 0.040-0.300 m³/t of liquid steel and intensity 5-30 m³/h during 30-70 min. Metal is de-oxidised with silicocalcium at flow rate to 60 kg of calcium per ton of liquid steel. Degassing is performed at steel flushing in ladle with nitrogen through porous bottom tuyeres at flow rate 5-40 m³/h during 10-40 min uner vacuum at pressure less 0.3 torr. Further, steel is flushed with nitrogen at flow rate 5-25 m³/h during 5-25 min to temperature 1515-1550°C.

EFFECT: raised physical-mechanical properties of steel due to reduced impurity with non-metallic inclusions; reduced consumption of calcium containing and nitrated ferro-alloys, reduced prime cost of melted steel.