PROCEDURE FOR REFINING RAIL STEEL IN LADLE Russian patent published in 2010 - IPC C21C7/00 

FIELD: metallurgy.

SUBSTANCE: procedure consists in metal arc heating, in melt inert-gas flashing through porous bottom tuyeres and in treatment of metal with slag in furnace-ladle aggregate and in vacuumiser. Metal is arc-heated in the furnace-ladle aggregate to temperature 1585-1610°C and is flashed with combined nitrogen and argon through porous bottom tuyeres. When common amount of introduced nitrogen reaches 0.30 m³/t of liquid steel, flashing is switched to argon. Flashing with argon is carried out at rate 3-30 m³/h; further metal is deoxidised with silica-calcium at consumption rate of 110-150 g of calcium per ton of liquid steel and is vacuumised when steel is flashed in the ladle with nitrogen through porous bottom tuyeres at rate of consumption 4-36 m³/h during 8-65 min under vacuum and at pressure less, than 34 MPa. Steel is subjected to combined flashing with nitrogen at consumption rate 3-50 m³/h to concentration of nitrogen in steel not more, than 25 ppm and successive flushing with argon to temperature 1520-1545°C.

EFFECT: reduced prime cost of melted steel, upgraded physical-mechanical properties of steel due to reduced impurity with non-metallic inclusions, also reduced consumption of nitrated and calcium containing ferroalloys.