refractory coating is a mud paste-like material used as a working lining or protective lining or protective lining on the surface of the refractory lining. Its solid/liquid mass ratio or volume ratio is similar to refractory mud. It is a kind of Bingham-type fluid mud with small yield value. It has good spreadability and can be applied manually (brush) or mechanical spraying method.
Generally, the refractory coating materials used in high-temperature kilns are made of phosphate or low-cement binder, but these binding methods must be used under specific conditions of use due to the performance of the binder, and there are corresponding shortcomings.
The refractory smear with phosphate as binder has good bonding performance. It can be used to coat the side wall and top of the kiln. However, according to the use conditions (such as air temperature), a certain coagulant should be added to adjust the hardening during construction. For example, if cement is used as a coagulant, it needs more than 16 hours of curing to harden, and it has to be baked at more than 500 ℃ to have good performance. If the baking temperature is lower than 450°C, the phosphate-bonded refractory may be damaged because the orthophosphate bond phase is not formed. If the temperature is too high (such as 1000°C), the phosphate-bonded refractory may be damaged by the aluminum phosphate and calcium phosphate bond phases. softening and loss of wear resistance.
The spread with low cement as binder has poor adhesion and slow hardening. Using cement as a binder requires at least 24 hours of curing to harden. Because of its poor adhesion, it is difficult to coat the side walls of the kiln, and it cannot be used for the top coating.
2 Technical properties of fast-hardening wear-resistant refractory castables
The quick-hardening refractory coating material is composed of brown corundum, electric ceramic material, high alumina bauxite, alumina micropowder, silica micropowder, calcium aluminate cement, heat-resistant steel fiber and chemical additives. It has good construction performance, fast hardening speed, With excellent wear resistance, it can meet many requirements such as rapid construction, emergency maintenance and wear resistance of kiln pipes and related equipment.
The quick-hardening refractory spray coating is based on brown corundum as the main aggregate. Because of its high hardness and wear resistance, it is supplemented by the toughening effect of heat-resistant steel fibers, which effectively improves the anti-peeling performance of the material, so that the material can be The surface wear resistance and erosion resistance are significantly improved.
The refractory smear is made of calcium aluminate cement plus polyacrylic acid latex as a composite binder. During construction, polyacrylic acid latex is used to obtain excellent adhesion. The smear can not only be applied to the side walls, but also to the top. It is also extremely convenient.
3 Application effects
Many equipment and pipelines in the contemporary cement industry have been scoured by materials and high-concentration dust-containing gases for a long time, and the downtime caused by wear and tear accounts for 50% to 55% of the total downtime. Such as the outlet of the vertical mill separator, the outlet air duct of the mill, the separator, the chute of the ball mill, the hopper, the inner cavity of various valves, the gate and the conveying pipeline, etc., the use of fast-hardening refractory coating will definitely improve the cement equipment. Wear resistance of related parts, reduce the consumption of wear-resistant materials, greatly improve the service life of wear-resistant parts, improve equipment operation efficiency, reduce costs, and save resources and energy.
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