A soft blowing method and control device for argon blowing at the bottom of a continuous casting ladle rotary table

Abstract

The present invention provides a method and a control device for blowing argon at the bottom of a continuous casting ladle turret, which transfers part or all of the soft blowing in the late stage of LF refining in the prior art from the LF refining treatment position to the continuous casting ladle turret. The position to be poured on the ladle turret is left still for manual ventilating brick blowing and soft blowing. During the pouring process at the pouring position, the automatic soft blowing mode and automatic blowing plugging are selected, and different automatic soft blowing modes are selected according to the different requirements for the control of inclusions in the steel. Blowing mode, in different automatic soft blowing modes, the proportion of molten steel pouring to the total molten steel in the ladle is different, and the types of breathable bricks selected are different. Compared with the soft blowing method in the later stage of LF refining in the prior art, the soft blowing time of the LF refining treatment position is saved by 3 to 8 minutes, and the average temperature drop of molten steel in the ladle is reduced by more than 0.12°C / min compared with the same period last year. The weight of electrolytic inclusions in continuous casting slab samples decreased by 7% to 20% year-on-year, and the qualified rate of casting slab quality increased by 0.01% year-on-year.

Description

technical field [0001] The invention relates to a control device and a soft blowing method for blowing argon at the bottom of a rotary table of a continuous casting ladle, and belongs to the technical field of steelmaking process in iron and steel metallurgy. Background technique [0002] In the prior art, after the ladle is refined from the LF refining position, it is hoisted to the pouring position of the continuous casting ladle turret, and then enters the pouring position for casting. Bottom blowing argon in the LF refining ladle is a simple and efficient refining technology outside the furnace. It is generally divided into two stages: large flow argon blowing, stirring and mixing in the early stage and soft blowing with low flow rate to remove inclusions in the later stage. At present, domestic LF refining ladles of more than 100 tons generally use two bottom-blowing permeable bricks. The processing time of high-quality steel is generally more than 40 minutes, and the s...

AI Technical Summary

Problems solved by technology

At present, domestic LF refining ladles of more than 100 tons generally use two bottom-blowing permeable bricks. The processing time of high-quality steel is generally more than 40 minutes, and the soft blowing time is generally 8-12 minutes. At present, the following problems or deficiencies exist in production practice: (1) Restricted by the production rhythm of steelmaking and continuous casting, the soft blowing time is insufficient, which affects the removal effect of inclusions; (2) The excessively long LF refining time causes the furnace machine to not match, which becomes a restrictive link for increasing production and efficiency ;(3) The air brick is easy to block, resulting in small flow rate in the early stage or the bottom blowing cannot be opened, which affects the metallurgical effect of the bottom blowing; (4) The flow control of the soft blowing is not accurate, and the flow rate is too small to affect the effect of the soft blowing to remove inclusions, and the flow rate is too large It also causes problems such as exposed steel surface, slag rolling and large temperature drop of molten steel.

[0003] Chinese patent document CN101586177A (200810011559.9) discloses a method for reducing titanium inclusions in molten steel. The control method makes the metallurgical effect of argon blowing in large-capacity ladles poor, and the amount of poured molten steel X in this invention is a calculated value. In actual production The casting speed of ladle pouring is changing, and the argon blowing flow value calculated from this is inaccurate, resulting in inaccurate control of the real-time argon blowing flow rate. Too large or too small argon blowing flow rate will directly affect the removal rate of inclusions, and because The argon blowing flow rate is large, the argon blowing time is long, and the molten steel temperature drop is large during the argon blowing process, so it is difficult to ensure the qualified continuous casting pouring temperature

Chinese patent document CN109719290A (201910126742.1) discloses an argon-blowing metallurgical method for ladle annular seam type breathable upper nozzle block. service life, thereby increasing the refractory cost of the ladle lining

[0004] And in production, different steel types have different requirements for inclusions. The argon blowing method in the prior art has unreasonable adjustment of argon flow rate, and poor air permeability of the permeable bricks, which cannot meet the control requirements of different steel types. lack of

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