Converter 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:

1. Mechanical impact erosion.

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

2. Physical effects.

During the smelting process, the airflow in the furnace scoured the furnace wall, 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 converter 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 converter 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, and it will be lost and eroded by the flue gas and fluid.

The main maintenance methods of the converter are:

1. Converter gunning

Converter gunning is the most important means of converter maintenance. By spraying refractory materials with a certain humidity to repair the corroded or falling off furnace lining, it can ensure normal and safe production and improve the life of the converter. The choice of gunning material needs to consider sinterability. Choose gunning material with good wettability, easy sintering and high refractoriness with the converter lining refractory material to improve the repair quality and reduce the gunning consumption and repair cost.

2. Protect the furnace by splashing slag

Slag splash protection is also an important means of converter maintenance. It uses oxygen lances to spray the slag with adjusted viscosity and properties on the furnace wall by using nitrogen after the converter is tapped to form a layer of protective lining. The erosion and melting loss of the furnace lining during the smelting process.

Under normal conditions, the economic life of large and medium-sized converters is generally in the range of 5000 to 8000 furnaces. Generally, new furnaces need to be protected by slag splashing and gunning repairs for about 500 furnaces. In the initial stage, the furnace is protected once for 2, 3 furnaces. After that, the frequency of furnace maintenance increases with the increase of furnace age. In the later period, slag splashing is required for each furnace. (Source: Iron and Steel United Network)