Converter tapping dephosphorization method of interstitial free steel

Abstract

The invention provides a converter tapping dephosphorization method of an interstitial free steel. The method comprises steps of: at a converting endpoint, controlling oxygen value and carbon content in steel at 600-900 ppm and 0.030-0.050wt%; plugging a tapping port before tapping, and stopping the slag with slag stopping dart during tapping for no less than 5 min; at the same time, controlling hanging tank temperature according to different tank batches: at 1 / 3 of converter tapping, adding lime, converter slag, fluorite and iron oxide according to a certain amount to realize a rapid dephosphorization reaction. According to the invention, converter tapping dephosphorization rate of the IF steel can reach 30-50%; and pressure in the converter is significantly reduced; and one-time successful rate and the yield of liquid steel are improved. Compared with prior art, the invention has the characteristics of small usage amount of dephosphorization agent, low cost, small tapping temperature drop and little energy consumption.

Description

technical field [0001] The invention belongs to the field of steelmaking technology, and in particular relates to a method for dephosphorizing molten steel during the tapping process of converter smelting interstitial atom-free steel (IF steel). Background technique [0002] The finished P content of IF steel is relatively high, and the P content of some IF steel products is required to be below 0.012 wt%, and the P content of individual IF steel products is even required to be below 0.010 wt%, which puts forward very high requirements for converter smelting . At the end of blowing, the furnace director often continues to dephosphorize by point blowing, but this often causes overoxidation of molten steel, reduces the yield of molten steel, increases the amount of deoxidizer, especially increases the inclusion of oxides in molten steel, directly Affect the pourability of molten steel. [0003] At present, steel mills generally adopt the method of adding dephosphorization ag...

AI Technical Summary

Problems solved by technology

At the end of blowing, the furnace director often continues to dephosphorize by point blowing, but this often causes overoxidation of molten steel, reduces the yield of molten steel, increases the amount of deoxidizer, especially increases the inclusion of oxides in molten steel, directly Affects the pourability of molten steel

[0003] At present, steel mills generally adopt the method of adding dephosphorization agent into the converter furnace or adding dephosphorization agent and argon blowing and stirring when tapping the converter. The former method uses a large amount of dephosphorization agent and is expensive. ; while the latter method leads to a large drop in tapping temperature, which requires the converter to increase the tapping temperature or compensate the temperature in the refining furnace, resulting in relatively prolonged smelting time and increased energy consumption