Refined slag control method

Abstract

The invention provides a refined slag control method for improving castability of small square billet killed steel and belongs to steelmaking refinement control technologies. Aluminum wires are ensured not to be fed into a ladle furnace (LF) by adding sufficient aluminum alloy to perform deoxidization and adding an appropriate amount of synthesized slag to perform washing, simultaneously CaO, CaF2 and Al2O3 are adopted in the LF refining process to perform slag formation, slag charges are added in a batch mode, aluminum particles are scattered on the slag surface in the refining process according to the slag situations to ensure the slag reducibility, and finally final slag components are controlled as follows: CaO=45-55%, Al2O3=35-40%, MgO=5-10%, and SiO2<=5%. Therefore, the flowability of a slag system is good, steel slag interfacial reaction is facilitated, absorption of oxide inclusion in molten steel is facilitated, accordingly conversion and removal of aluminum deoxidized inclusion in the molten steel are promoted, the feeding amount of Ca wires can be decreased, even the Ca wires are not fed, the castability of the molten steel is good, and the liquid level of a crystallizer is stable.

Description

technical field

[0001] The invention belongs to the technical field of iron and steel smelting, and in particular relates to a refining slag control method for improving the pourability of billet aluminum-killed steel. Background technique

[0002] When using converter-CAS station-LF refining furnace-billet continuous casting process to produce aluminum-killed steel, the aluminum deoxidation product in molten steel has a high melting point and is difficult to remove, resulting in poor castability of molten steel, especially for small billets. Due to the small diameter of the pouring nozzle of the billet continuous casting machine, it often causes nozzle knots and crystallizer liquid level fluctuations due to poor castability, which often burns oxygen at the nozzle and frequently replaces the nozzle, and even causes the stoppage of casting, which seriously affects The quality of the cast slab is reduced, and the production cost is greatly increased.

[0003] Production plant...

Examples

Embodiment 1

[0016] Embodiment 1: Control method of refining slag. The process steps are as follows:

[0017] The molten iron is pretreated before entering the furnace. After the treatment, the sulfur content of the molten iron is S: 0.011%, and the temperature is 1296°C. The slag must be cleaned before the molten iron enters the converter. Converter smelting adds molten iron and scrap steel, 86 tons of molten iron and 12 tons of scrap steel. Converter end point control C=0.050%, P=0.015%, temperature 1635°C; strict slag blocking, slag thickness ≤ 50mm, tapping time 5min, 1 / 5 of the tapping Add aluminum deoxidizer to the ladle for deoxidation, and at the same time 550kg of synthetic slag was added to the ladle, the alloy and slag were added to 2 / 5 of the steel, and other alloys were added according to normal requirements; the CAS station carried out strong argon blowing and stirring on the molten steel, the content of acid-soluble aluminum in the steel was 0.081%, and the temperature was ...

Embodiment 2

[0020] Embodiment 2: Control method of refining slag. The process steps are as follows:

[0021] The molten iron is pretreated before entering the furnace. After the treatment, the sulfur content of the molten iron is S: 0.015%, and the temperature is 1289°C. The slag must be cleaned before the molten iron enters the converter. Converter smelting adds molten iron and scrap steel, 89 tons of molten iron and 10 tons of scrap steel. Converter end point control C=0.060%, P=0.015%, temperature 1630°C; strict slag blocking, slag thickness ≤ 50mm, tapping time 5min, tapping 1 / 5 Add aluminum deoxidizer to the ladle for deoxidation, and at the same time 550kg of synthetic slag was added to the ladle, alloy and slag were added to 2 / 5 of the steel, and other alloys were added according to normal requirements; the CAS station carried out strong argon blowing and stirring on the molten steel, the content of acid-soluble aluminum in the steel was 0.076%, and the temperature was 1558 ℃, fe...

technical field

[0001] The invention belongs to the technical field of iron and steel smelting, and in particular relates to a refining slag control method for improving the pourability of billet aluminum-killed steel. Background technique

[0002] When using converter-CAS station-LF refining furnace-billet continuous casting process to produce aluminum-killed steel, the aluminum deoxidation product in molten steel has a high melting point and is difficult to remove, resulting in poor castability of molten steel, especially for small billets. Due to the small diameter of the pouring nozzle of the billet continuous casting machine, it often causes nozzle knots and crystallizer liquid level fluctuations due to poor castability, which often burns oxygen at the nozzle and frequently replaces the nozzle, and even causes the stoppage of casting, which seriously affects The quality of the cast slab is reduced, and the production cost is greatly increased.

[0003] Production plant...

Examples

Embodiment 1

[0016] Embodiment 1: Control method of refining slag. The process steps are as follows:

[0017] The molten iron is pretreated before entering the furnace. After the treatment, the sulfur content of the molten iron is S: 0.011%, and the temperature is 1296°C. The slag must be cleaned before the molten iron enters the converter. Converter smelting adds molten iron and scrap steel, 86 tons of molten iron and 12 tons of scrap steel. Converter end point control C=0.050%, P=0.015%, temperature 1635°C; strict slag blocking, slag thickness ≤ 50mm, tapping time 5min, 1 / 5 of the tapping Add aluminum deoxidizer to the ladle for deoxidation, and at the same time 550kg of synthetic slag was added to the ladle, the alloy and slag were added to 2 / 5 of the steel, and other alloys were added according to normal requirements; the CAS station carried out strong argon blowing and stirring on the molten steel, the content of acid-soluble aluminum in the steel was 0.081%, and the temperature was ...

Embodiment 2

[0020] Embodiment 2: Control method of refining slag. The process steps are as follows:

[0021] The molten iron is pretreated before entering the furnace. After the treatment, the sulfur content of the molten iron is S: 0.015%, and the temperature is 1289°C. The slag must be cleaned before the molten iron enters the converter. Converter smelting adds molten iron and scrap steel, 89 tons of molten iron and 10 tons of scrap steel. Converter end point control C=0.060%, P=0.015%, temperature 1630°C; strict slag blocking, slag thickness ≤ 50mm, tapping time 5min, tapping 1 / 5 Add aluminum deoxidizer to the ladle for deoxidation, and at the same time 550kg of synthetic slag was added to the ladle, alloy and slag were added to 2 / 5 of the steel, and other alloys were added according to normal requirements; the CAS station carried out strong argon blowing and stirring on the molten steel, the content of acid-soluble aluminum in the steel was 0.076%, and the temperature was 1558 ℃, fe...

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