Refractory materials for the taphole of the converter are easily affected by many aspects in use. The main damages to the price of magnesia carbon bricks are as follows:

1. Oxidation of furnace gas

From the molten iron in the converter to the blowing process, the tapping port is in a high-temperature erbium atmosphere. The furnace gas generated during the blowing process contains a large amount of CO. When it is discharged from the tapping port, CO reaction occurs at the tapping port. A decarburization layer is formed on the surface of the inner wall, which directly causes damage to the tapping hole.

2. Friction damage and mechanical erosion damage of molten steel and slag

When tapping steel, the tap hole has to withstand the huge pressure of molten steel in the converter. At the same time, when molten steel and slag flow out of the tap hole, they will friction and scour the inner wall of the tap hole, directly causing mechanical damage to the inner wall of the tap hole.

3. High temperature melting of molten steel and slag

The tapping temperature is generally 1680~1710℃. Under the action of high temperature molten steel, the material of the tapping mouth will soften, the strength will be significantly reduced, and it will even melt, resulting in damage to the tapping mouth.

4. See Table 1 for the physical and chemical indicators of the chemical erosion of molten steel and slag.

When the converter smelting reaches the end point of tapping, molten steel generally has strong oxidizing properties, especially the slag has higher oxidizing properties. Under high temperature and high oxidizing conditions, the following chemical reactions will occur:

C+O→CO↑ (1)

MgO+ C→Mg↑+CO↑ (2)

In the process of chemical reaction, W(O) in molten steel or slag will deprive carbon from magnesium tapping material, which makes the structure of refractory material loose and its strength deteriorates. In addition, if the basicity of the slag is too low or the mass fraction of MgO in the slag is low, the following chemical reactions will occur:

SiO2+C→SiO + CO↑ (3)

will also aggravate the chemical erosion of the tap hole.