Which Refractory Material is Mainly Used in Steelmaking

Steelmaking mainly uses semi-acid raw materials (mainly refractory clay): In the previous classification, clay was listed as acidic raw materials, which is inappropriate. The acidity of refractory raw materials is based on free silica (SiO2). The reasons are as follows:

1. Because according to the chemical composition of refractory clay and siliceous raw materials, the free silica in refractory clay is much less than that of siliceous raw materials.

2. Because there are 30% to 45% alumina in general refractory clay, alumina is seldom in a free state, and it must be combined with silica to form kaolinite. Even if there is a small amount of excess silica, the effect is also Very small.

3. Therefore, the acidic properties of refractory clay are much weaker than those of siliceous raw materials. Refractory clay decomposes into free silicic acid and free alumina at high temperatures, but it does not remain unchanged. Free silicic acid and free alumina will combine to form Yinglai stone when it continues to be heated. Yinglai stone has good acid resistance to alkaline slag. At the same time, due to the increase of alumina content in refractory clay, its acidity gradually weakens. When the alumina reaches 50%, it will appear alkaline or neutral, especially if It is a clay brick made under ultra-high pressure, with high density, fineness and tightness, and low porosity.

4. It is more resistant to alkaline slag than silica under high-temperature conditions. In terms of its corrosiveness, Yinglai stone is also very slow, so it is more appropriate to classify refractory clay as a semi-acidic raw material. Refractory clay is a widely used raw material in the refractory industry.