The cause of slagging in ladle slag line

 1. For a long time to be poured, the top slag of molten steel cools and crusts, causing slagging on the ladle slag line.

(1) The cold heading steel process of Shaoguan Steel Plant requires bottom blowing of argon after the calcium treatment, weak blowing for 12-20 minutes. During the weak blowing process, the edge of the slag layer on the surface of the molten steel is basically in a static state. After a long period of temperature loss, the slag temperature continues decrease, the slag layer close to the ladle wall will solidify at the position of the ladle slag line, causing slagging on the ladle wall.
(2) The smelting cycle of the converter is shorter than the smelting cycle of the LF refining furnace, the pouring order is inadequate, the smelting speed of the previous process is too fast, the backlog of molten steel in the refining area is serious, and the waiting time is too long after the refining and smelting is completed until the continuous casting and casting. This is the main cause of slagging in the ladle slag line.

2. The Al2O3 content in the cold heading steel slag system is high, and the molten steel slag is sticky. After the refining is completed, the molten steel will solidify and condense at the position of the ladle slag line as the temperature of the slag surface decreases during the process of quenching.
According to field observations, when smelting aluminum killed steel, the ladle slag line is prone to slagging, while when smelting silico-manganese killed steel, the ladle slag line is slightly sticky.
The content of Al2O3 in aluminum killed steel slag is high [2]. In order to ensure the purity of molten steel, the amount of lime added is also large, forming a thicker and denser slag crust; silico-manganese killed steel does not contain Als, which produces Al?O? is also very small, so the amount of lime added is small and the slag layer formed is thin. It can be inferred that ladle slagging is greatly affected by the content of Al?O? in the slag.

3. The ladle slag line bricks are eroded seriously, causing depressions and slagging easily. Ladle slag line bricks refer to refractory bricks built from the third to the eighth layer of bricks from the bottom of the ladle mouth. After the ladle is filled with steel, the molten steel level fluctuates up and down with the amount of molten steel. When the converter smelting is finished, the partial oxide slag in the furnace is poured into the ladle along with the molten steel, commonly known as "slag". Sub-refining and slagging are used to remove excess oxygen in molten steel, that is, "deoxidation". The deoxidized slag is reduced slag.
As the alkalinity in the slag changes, the refractory bricks on the ladle wall that contact the slag are gradually dissolved and fall off, forming a depression in the ladle wall. When the alkalinity in the slag stabilizes, the slag and the ladle slag line bricks are mutually dissolved and combined to form slagging. The recessed wall of the slag will hang support points for the slagging, making slagging more and more easier.
In order to save costs and increase the turnover rate of the ladle, the ladle slag line bricks are not repaired in time after being etched, or the standard use is reduced, which greatly increases the probability of ladle slagging. Ladle slag line bricks have poor quality, poor corrosion resistance, poor permeability resistance, and quality problems such as cracks, which accelerate the erosion of the ladle slag line bricks and accelerate the slagging of the ladle slag line.

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Article Source:The cause of slagging in ladle slag line
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