Mainly siliceous raw materials, such as: quartz, tridymite, cristobalite, chalcedony, flint, opal, quartzite, white silica sand, diatomite, ramming material, these siliceous raw materials contain silicon oxide (SiO2) at least 90, the pure raw material is silicon oxide 99. Siliceous raw materials are acidic in the high-temperature chemical dynamics. When metal oxides are present in contact with them, they play a chemical role combine to form fusible silicates. Therefore, if the silicon material contains a small amount of metal oxide, its heat resistance will be seriously affected.
Uses functions of five types of natural refractory raw materials
2. Semi-acidic raw materials (mainly refractory clay)
In the past classification, clay was listed in acidic raw materials, which is actually inappropriate. The acidity basis of refractory raw materials is based on free silica (SiO2), because according to the chemical composition of refractory clay siliceous raw materials, the free silica in refractory clay is much less than that of siliceous raw materials. Because there is 30%-45% alumina in general refractory clay, alumina is rarely in a free state, it combines with silica to form kaolinite (Al2O3·2SiO2·2H2O), even if there is excess silica The effect is very small. Therefore, the acidic nature of refractory clay is much weaker than that of siliceous raw materials. Some people believe that refractory clay decomposes into free silicic acid free alumina at high temperature, but it does remain the same. Free silicic acid free alumina will combine to form enlite (3Al2O3·2SiO2) when heated. Ying Laite 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 alumina reaches 50%, it will appear alkaline neutral. Clay bricks made under pressure have high density, compactness, low porosity, are more resistant to alkaline slag under high temperature conditions than silica. In terms of its corrosivity, Ying Lai stone is also very slow, so we think it is more appropriate to list refractory clay as a semi-acid raw material. Refractory clay is a basic versatile raw material in the refractory industry.