What kind of refractory materials are mainly used in steelmaking

Steelmaking mainly uses semi-acidic raw materials (mainly fireclay) : in the previous classification, clay is listed in the acidic raw materials, which is actually not suitable. The acidity of refractory raw materials is based on free silica (SiO2) as the main body, for the following reasons:

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

2. Because there is 30% to 45% alumina in the general fireclay, and alumina is rarely free, it must be combined with silica to form kaolinite, even if there is little excess silica, the effect is very small.

3. Therefore, the acid property of fireclay is much weaker than that of siliceous raw materials. The fireclay is decomposed into free silicic acid and free alumina at high temperature, but it is not unchanged, and free silicic acid and free alumina will be combined into quartz when it is continued to be heated. Quartz has good acid resistance to alkaline slag, and due to the increase of alumina in the refractory clay, its acidic substances gradually weaken, when the alumina reaches 50%, there will be alkaline or neutral properties, especially the clay brick made under ultra-high pressure, high density, fine and compact, low porosity

4. The resistance to alkaline slag is stronger than silica under high temperature conditions. In terms of its erosion, quartz is also very slow, so it is more appropriate to classify fireclay as semi-acidic raw materials. Fireclay is a widely used raw material in the refractory industry.