The cement kiln has high working temperature, large heat load, easy change of raw material composition, and harmful gas in the evaporation place, so the selection of refractory materials is relatively strict.
The refractory lining of the cement rotary kiln is the weakest link of the kiln lining, especially the refractory lining of the front kiln. The use temperature is about 1100. It needs to withstand the sudden change of the temperature difference between the rapid heat and the quenching, plus the high temperature cement clinker wear. And high temperature harmful gas alkali corrosion. It is also the reason that the lining body is easily cracked, peeled off and abraded, so that the refractory castable is required to have thermal shock resistance, wear resistance and alkali resistance. If the deformation of the kiln mouth of the rotary kiln can be poured with refractory castables, the steel shells are welded with anchoring nails, and the cultivator is reinforced with steel fiber refractory castables, which are constructed and baked according to the regulations to improve the high temperature resistance and resistance of the kiln mouth lining. Abrasive performance. Generally, refractory castables of corundum and high-aluminum steel fibers are used in the past, but the aluminum content is high and the strength is high, which reduces the heat resistance and reduces the service life. Therefore, the replacement of corundum and high-aluminum refractory castables with steel fiber refractory castables can improve the service life of the kiln mouth.
The refractory aggregate is made of second-grade alumina clinker, coke gemstone and mullite. The critical diameter is enlarged, and the particle gradation should be reasoned to achieve densification, which is beneficial to improve the thermal shock resistance and strength of the material.
Materials such as refractory powders, binders and admixtures are the matrix materials for refractory castables and must be properly graded to improve their performance. At normal temperature, the construction strength can be obtained, and under the action of high temperature, phase transformation and sintering are likely to occur. At the same time, in-situ reaction occurs between the materials, and the micro-expansion can offset the sintering shrinkage and improve the thermal shock resistance and strength of the castable.
The refractory powder is made of corundum, bauxite clinker, mullite and silicon carbide, and is broken into various grades for assembly. At the same time, ultra-fine powder should be added to fill the voids, and the activity is large, and it is easy to generate in-situ reaction and improve matrix performance.
The binder is selected from calcium aluminate cement, ultrafine powder and phosphate, and is generally used in combination; the amount thereof should ensure the strength of demoulding, and the drying compressive strength reaches about 40 MPa.