Fast hard refractory coating and its application

Refractory coatings are pasty materials used as working lining or protective lining or protective lining on the surface of refractory lining. Its solid/liquid mass ratio or volume ratio of refractory mud is similar, is a kind of small yield value of Bingham fluid mud, with good spreadability, dry materials can be used in the artificial coating (brush) or mechanical spraying construction.

Generally, phosphate or low cement are used as binders for refractory coatings used in high-temperature kilns. However, due to the properties of binders, these binders must be used under specific conditions, and there are corresponding shortcomings.

Phosphate as binder refractory coating has better bonding performance, it can be used for smearing furnace side wall and top, but construction conditions (such as air temperature), adding a certain accelerator to adjust the hardening performance, such as cement as accelerator, need more than 16 hours of curing to harden, but also after 500 C above. The baking side has good performance. If the baking temperature is lower than 450 C, the phosphate bonded refractories may be destroyed due to the absence of orthophosphate bonding phase. If the baking temperature is too high (such as 1000 C), the phosphate bonded refractories may lose wear resistance due to the softening of the aluminum phosphate and calcium phosphate bonding phase.

Low cement as binder has poor adhesion and slow hardening. It takes at least 24 hours for cement to be used as binder to harden. Because of its poor cohesion, it is difficult to smear the side wall of the kiln, and it can not be used in the top coating construction.

2 technical properties of fast hard wear-resistant castable

Quick-hardening refractory coating is composed of brown corundum, electric porcelain, bauxite, alumina powder, silica powder, calcium aluminate cement, heat-resistant steel fiber and chemical additives. It has the advantages of good construction performance, fast hardening speed and excellent wear resistance. It can meet the requirements of rapid construction of kiln pipes and related equipment. Urgent maintenance, wear and tear, and many other requirements.

Fast hardening refractory spraying coating is made of brown corundum as the main aggregate. Because of its high hardness and wear resistance, and the toughening effect of heat resistant steel fiber, the spalling resistance of the material is effectively improved, so that the wear resistance and erosion resistance of the material surface are significantly improved.

Refractory coating is calcium aluminate cement with polyacrylic acid latex as a composite binder, the use of polyacrylic acid latex in construction to obtain excellent adhesion, the coating can not only be applied to the side wall, but also very convenient to apply the top. During curing, the reaction of Ca+ released by cement hydration with COOH gene in polyacrylic acid latex can make polypropylene polymer cross-linked and obtain strength quickly (about 7 h). At elevated temperature, CaO, Al2O3 and SiO2 from cement powder were reacted to form albite CaO, Al2O3, 2SiO2 and ceramsite to obtain intermediate temperature strength. In summary, the fast hardening and wear resistant refractory coating has good coating performance, hardening performance, strength performance and wear resistance, as shown in Table 1.

Table 1 performance of fast hardening refractory coating

3 application effect

Many equipment and pipelines in the contemporary cement industry have been scoured by materials and high concentration of dust gas for a long time. The downtime caused by wear and tear accounts for 50%~55% of the total downtime. For example, the use of fast-hardening refractory coating material at the outlet of vertical mill separator, outlet air duct of mill, separator, chute of ball mill, hopper, inner cavity of various valves, gate and conveying pipeline will certainly improve the wear resistance of cement equipment related parts, reduce the consumption of wear-resistant materials, and greatly increase the service life of wear-resistant parts. Improve equipment operation efficiency, reduce cost, save resources and energy.