Method for improving dephosphorization efficiency in duplex converter by using CO2

Abstract

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.

Description

technical field [0001] The invention belongs to the field of metallurgical technology and energy saving and emission reduction, in particular to a 2 A method for improving dephosphorization efficiency in a double converter. Background technique [0002] Metallurgical thermodynamics believes that the necessary conditions for dephosphorization are low temperature, high oxidation, high alkalinity slag and other technological factors. Metallurgical kinetics believes that it is necessary to strengthen the agitation of the molten pool during the dephosphorization period of steelmaking, increase the area of ​​the reaction interface, and ensure good fluidity of the process slag. At present, the traditional steelmaking process usually uses oxygen as the oxidant to complete the dephosphorization reaction. If the oxygen supply flow rate is too large, the dephosphorization reaction is easily limited by the thermodynamic conditions of the rapid temperature rise of the molten pool after...

AI Technical Summary

Problems solved by technology

However, the solid coolant is easy to cause partial cooling of the molten pool, so that the uniform cooling effect is not good and it is difficult to control. At the same time, the coolant contains a large amount of impurity elements, which increases the burden on the production of high-quality steel.

Some iron and steel enterprises, such as Japan's Nippon Steel, my country's Baosteel, Shougang Jingtang and other enterprises, adopt converter dual-smelting process. Phosphorus, but the stirring kinetics in the dephosphorization converter is poor, the molten steel peroxidation seriously leads to slag foaming, and the dephosphorization speed and efficiency are limited