Material requirements for refractory materials for refining outside the furnace

Furnace refining is an important part of obtaining high quality continuous casting molten steel. Now, “there is a continuous casting of a converter outside the furnace” or “alternative refining of the electric furnace” has become a more common mode.

Since the refractory material for refining outside the furnace is in a very harsh working environment, it is required to have the following properties:

(1) The refractory material itself has a low volatility under high temperature and vacuum.

(2) Erosion and erosion of boiling resistant steel under vacuum.

(3) It has high thermomechanical properties.

(4) It has good thermal shock resistance.

At present, the common refining devices commonly used in China are: RH, DH vacuum degassing devices, LF, VAD, AOD and ASEA— SKF refining bags. The refractory materials used in them mainly include: high alumina bricks, magnesia chrome bricks, corundum castables, magnesia carbon bricks and dolomite bricks.

The stability order of several refractory oxides under high temperature and vacuum is as follows:

A1203>CaO>MgO>Cr203

It can be seen that the high alumina brick is characterized by low evaporation and dissociation under high temperature and vacuum, and has good stability, but its corrosion resistance is not as good as other bricks, so it can be used for low corrosion in the refining device outside the furnace. Damaged areas, this is also more economical.

Magnesia-chrome bricks are characterized by better slag resistance, but they are inferior to magnesia bricks and dolomite bricks when the slag basicity is greater than 1.2. The thermal shock resistance is worse than that of high alumina bricks and magnesium bricks, but not as good as dolomite bricks. High temperature stability is not as good as high alumina bricks and dolomite bricks.