Ramming Material on the Requirements of Silica Sand

1. Purity The purity of silica sand and its refractoriness are closely linked, as the lining material, silicon dioxide silica should be greater than 98%. Silica sand harmful impurities in the lower the better, especially alkali metal oxides should be less than 0.2%, iron oxide should be less than 0.2% to 0.5%.
2. Crystallization conditions for the induction furnace lining material silica sand, are generally made of natural vein quartz processing. Natural quartz microstructure can be divided into two types of crystalline and cemented. Crystalline quartz crystal grain size is small, large to more than 1 ~ 2mm, medium of about 0.2 ~ 0.5mm, small only 0.01 ~ 0.08mm.Crystalline quartz crystal grain size is only 0.001 ~ 0.003mm. The crystals with coarse and lattice regularity and less defects are in a lower energy position. In the process of crystal transformation, more energy is absorbed, that is, crystalline transformation takes place at higher temperature. It is generally desirable for this type of conversion to take place at higher temperatures since the fine powder surrounding the quartz particles has a sufficient amount of liquid phase to buffer the larger volume of quartz particles that are produced during the crystal transition Expansion, and filling the crack due to particle cracks and cracks, thereby enhancing the density of the lining sintering. The temperature of the liquid phase in the fine powder has little to do with the crystallization state of the ore, mainly depending on the specific surface area of ​​the fine powder and the type and quantity of the binder added.
From the above, the silica sand in addition to the requirements of purity, but also requires the crystallization of coarse, less lattice defects, which is to ensure a satisfactory sintering furnace lining one of the factors.

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