BLAST FURNACE STEELMAKING METHOD Russian patent published in 2001 - IPC

FIELD: metallurgy. SUBSTANCE: method involves charging blast furnace with metal burden; heating and melting; working molten metal to required characteristics and purging it with neutral or inert gas supplied through multiple-nozzle purgers embedded in hearth porous refractory layer. Bath is purged with neutral or inert gas supplied through bath hearth with intensity variable in the course of melting process from 1.3 •10^-2 cu.m/t to 15 •10^-2 cu. m/t of molten metal. At the initial melting period, gas flow rate is 1.3 •10^-2-3.0 •10^-2 cu.m/t of molten metal. As weight of molten metal increases, gas flow rate is increased to 15.0 •10^-2 cu.m/t of molten metal. Molten metal is purged in zones distributed along longitudinal axis of furnace. Gas is supplied to each zone from purger with at least 20 nozzles having diameter of 0.70-3.2 mm at gas pressure of 1-6 atm. Gas is supplied through layer of refractory material of 2-10 mm fraction for providing specific purging density in each zone within the range of 2.0-11.5 cu.m hour per 1 sq.m of its surface. Total gas flow rate of at least 0.40 cu.m/t is maintained for the entire melting cycle, and it is increased in case of reduced carbon content in melt at time before metal finishing period. EFFECT: intensified heat-mass exchange processes under basic extent of liquid metal loss and dusting conditions. 3 cl, 1 ex