The invention provides a method for improving the dephosphorization efficiency in a duplex converter by using CO2 and belongs to the field of
metallurgy technologies and
energy conservation and emission reduction. According to the method for improving the dephosphorization efficiency in the duplex converter by using the CO2, top-blowing of the
mixed gas of the CO2 and
oxygen is conducted in a dephosphorization furnace, bottom-blowing of the CO2 and
nitrogen in are conducted in a time-dividing-section switching mode, the CO2 is adopted in blowing, and the
nitrogen is adopted for keeping the smoothness of a bottom blow gun when converter reversing and gun lifting are conducted until
smelting blowing is started (the non-blowing period). When the
phosphorus content is reduced to be lower than 0.030%, molten iron after dephosphorization is added into a
decarburization furnace, the top-blowing of the
mixed gas of the CO2 and
oxygen is conducted for deep dephosphorization in the
smelting earlier stage of the
decarburization furnace, the gas is switched into
pure oxygen for
decarburization warming in the middle and later period, the bottom-blowing of the
nitrogen or the CO2 or
argon is conducted, and the end point
phosphorus can be reduced to be lower than 0.010%. According to the method for improving the dephosphorization efficiency in the duplex converter by using the CO2, through the adjustment of the blown gas types and the proportion, the concentration of the
oxidizing agent is reasonably controlled to reach the effects of improving converter dephosphorization reaction
thermodynamics and dynamic conditions, the dephosphorization efficiency and the
molten steel quality are improved, the
resource utilization of the CO2 in steel-making processes is achieved, and the
sustainable development of the iron and steel industry is promoted.