Corrosion mechanism and protection of BOF lining

 BOF smelting is a series of physical and chemical reaction processes under high temperature conditions. In this process, the furnace lining is corroded by a series of strong mechanical, physical and chemical effects. The main mechanism is as following,

1. Mechanical impact erosion.

The operations such as adding scrap steel and mixing molten iron directly face the large-surface furnace lining of the BOF, which produces strong impact, wear and erosion on the large-surface furnace lining, which are the main factors for the corrosion of the refractory lining of the furnace.

2. Physical effects.

During the smelting process, the airflow in the furnace scoured the furnace wall, the furnace cap and other refractory materials, the molten steel and slag melted and washed the furnace lining, and the high temperature reaction during the smelting process caused physical erosion of the furnace lining.

3. Chemical action.

The working layer of the BOF lining is generally made of magnesia-carbon bricks. The magnesia-carbon bricks contain a certain amount of graphitic carbon, which has poor wettability with the slag and can hinder the penetration of the slag into the brick body; the thermal conductivity is good and can greatly improve the thermal vibration resistance of the lining brick, so that the magnesia carbon brick lining life is longer. However, there is a strong oxidizing atmosphere in the BOF furnace. During the smelting process, high-temperature oxidizing gas will oxidize and remove part of the carbon in the brick, causing the brick structure to become loose and brittle, which will be lost and eroded by the flue gas and fluid.

Article Source: Corrosion mechanism and protection of BOF lining
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