Unshaped refractory materials commonly used in the cement industry are mainly composed of refractory castables, refractory ramming materials and refractory spray coatings. The most widely used is refractory castable.
Light alkali resistant castable
In cement and decomposition kilns, lightweight alkali-resistant castables are mainly used as alkali-resistant thermal insulation linings in areas subject to alkali corrosion, such as preheater decomposition furnace piping systems and ordinary dry-process rotary kiln preheating decomposition zones. It is suitable for parts that require both alkali resistance and high strength and wear resistance.
Alkali-resistant castable
Compared with the lightweight alkali-resistant castables, the alkali-resistant castables have higher strength and refractoriness, while the thermal conductivity is relatively large, which is different in use.
High-strength refractory castable
High-strength refractory castables are mainly used for parts that are easy to wear in thermal kilns, such as kiln mouths and coal injection pipes. It is formulated with corundum as aggregate, high-quality high-alumina cement as binder, and a small amount of additives. However, this kind of castable is prone to porosity during the pouring process, and it is prone to peeling during the pouring process, and the strength growth is relatively slow.
Steel fiber reinforced refractory castable
Refractory injection prepared by using high alumina bauxite clinker or corundum as aggregate and powder, adding binding agent and appropriate amount of heat-resistant stainless steel fiber, or adding appropriate additives. The proportion of steel fiber in the clinker should be 4% (weight ratio). Steel fiber in the refractory castable greatly improves the anti-stripping performance of the refractory castable. The distribution of steel fibers has a great influence on the quality of concrete, and random distribution is better. Therefore, the time of vibrating should not be too long. The steel fiber castable must be poured at one time, otherwise, the possibility of peeling between the two layers is very high.
High-strength mullite refractory castable for cement kiln
High-strength mullite refractory castables for cement kilns use mullite as the main raw material, and the alumina content index is required to be ≥65%. In addition, other auxiliary materials such as cement, silica fume, and high wear-resistant materials must be added. The main impurity of high-strength mullite refractory castable for cement kiln is iron oxide. The content of iron oxide is controlled within a certain range (≤1.5%), which is beneficial to the stability of the material and improves the high-strength mullite refractory castable for cement kiln Performance.
Other refractory castables
Low-cement refractory castables can effectively avoid the regret of high-temperature performance. Refractory castables with a cement content of less than 8% are called low cement refractory castables, and those with a cement content of less than 4% are called ultra-low cement refractory castables. Compared with ordinary refractory castables, its structure is dense, the apparent porosity is low, the refractoriness is high, the high temperature strength is high, the load softening temperature is high, and the thermal shock performance is good. However, due to the low cement content, the setting time is long and the early strength is low, which is particularly disadvantageous for construction in winter and low temperature conditions.
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