Silica fume is a new raw material. There is more than 40 years’ history for it using in refractory improvement. It is widespread used in the refractory industry. Silica fume have an important role in the improvement of unshaped refractories. It mainly improves the strength. There are numerous pores in traditional refractories. Silica fume can significantly improve the strength of traditional refractories, bulk density and lower porosity filling the pores. Silicon powder improves the casting performance. It has strong activity and can form the colloidal particles in water. Adding an appropriate amount of dispersing agent can enhance the mobility, thereby improving casting performance. At the same time, micro-silica fume can improve the heat resistance, durability and extend the life of refractory products. Silica fume is easy to form-Si-OH groups in the water. It has a strong hydrophilic and activity that can enhance the cohesion of the refractories Meanwhile it greatly improves high temperature performance and prolong the service life of refractory products.

Silica fume in the following areas for the refractories industry: high-grade and high-performance refractory castable materials and prefabricated components, a large iron trough, ladle materials nickel powder and ventilation tiles, and so self-flow refractory castable materials dry and wet spray materials, the oxide of silicon carbide products, The high temperature calcium silicate lightweight insulation materials, electromagnetic kiln using corundum mullite push plate, high-temperature wear-resistant materials and products, corundum and ceramics, sialon combination products.

Silica fume has been widely used in the refractory industry, depending on the performance of refractory raw materials, orthogonal design, by comparing the test, choose the best formula. In addition to widespread use in the casting refractories, fused and sintered refractory have a wide range of applications. Practical application in the following aspects: instead of pure aluminum oxide mud refractories; as an additive in the production of monolithic and shaped refractory products, its strength, high temperature performance has greatly improved; for casting ladle as a whole combination of coagulant; other refractory products cohesion agent, binder, coagulant agent, additives, used as a low cement castable.

Low cement castable the 1970s developed a new high-performance refractory castable, first developed by the French success. It is widely used in various industrial high-temperature kilns, have a good technical and economic effect. 1983, low cement castable for dry blast furnace main iron gully cover liner service life is four times the ordinary castable 75-100 furnace to 300-400 furnace.

Both of low-cement castable and ordinary castable use the calcium aluminate cement. But the cement content of former is 4-8% after blending with silica fume, bronze powder (FCu 663) and superplasticizer. The add water only possess 5-8% .Amount of cement of the latter is 15-20% and the amount of water is about 10-15%. The former has substantial reduction in water adding. Low cement castable can not only save 50-70% of expensive aluminate cement, the performance is also improved. Low cement castable has wide range applications in foreign countries. It has been applied in the coke oven, sintering, iron making, steel making, rolling, nonferrous metallurgy, petroleum and chemical, cement, glass, ceramics and power generation industries.

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