Kiln Mouth Refractory Castables

Besides bearing high temperature, the kilneye Refractory Castable needs to bear the damage caused by mechanical stress, heat stress and chemical corrosion during the use. According to its actual working condition, our company has developed the special kilneye Refractory Castable . It is of behaviors of high mechanical strength,high refractoriness, good thermal shock resistance and alkali resistance, and of 10 to 12 months' life cycle, gaining high praise of users.

The refractory lining of the kiln mouth of the rotary kiln is the weak link of the kiln lining, especially the refractory lining of the front kiln mouth, which has a service temperature of about 1100℃ and needs to withstand the impact of rapid cooling and rapid hot air flow, high-temperature cement clinker wear and high-temperature harmful gas alkali corrosion, etc. The service conditions are very harsh. The damage of the lining is mainly: cracking, spalling and abrasion, so the refractory material must have good thermal shock resistance, wear resistance and alkali resistance.

 

When the kiln mouth cylinder of the rotary kiln is not deformed, it can generally be built with shaped products such as anti-stripping high-alumina bricks, spinel bricks and directly bonded magnesia-chrome bricks, and high-quality mud is used as the joint material to form a whole, prevent bricks from falling off, and increase life. However, cylinder deformation is common, so refractory castables are poured, rivets are welded on the steel shell, steel fiber reinforced refractory castables are added to the castables, and construction and baking are carried out according to regulations to meet the production needs of the kiln mouth cylinder lining.

In foreign countries, corundum and high-aluminum steel fiber reinforced refractory castables are widely used in the kiln mouth of cement kilns, and their service life can reach 2 to 8. The castable has a high aluminum content and high strength. Therefore, the thermal shock resistance is poor, it is easy to crack and peel off, and the service life is reduced. Production practice has proved that the use effect of steel fiber reinforced high-aluminum refractory castables is better than that of corundum castables.

The steel fiber reinforced corundum and high-aluminum refractory castables used in the kiln mouth of the rotary kiln are prone to cracking and peeling after many years of use, that is, the thermal shock resistance is poor and the service life is low. Our company has developed high-aluminum refractory castables, high-aluminum mullite castables and mullite refractory castables, etc., with a service life of more than one year, and has achieved good use results.

It is well known that clay bricks are better than high-aluminum bricks in thermal shock resistance and alkali resistance because of low aluminum content; high strength, good wear resistance and poor seismic resistance. In the kiln mouth castable, the Al2O3 content is 50% to 70%, the strength is moderate (taking into account both wear resistance and suitable thermal shock resistance), and the drying and compressive strength (1100℃) are about 40MPa and 70MPa respectively. It should be pointed out that the refractory castable is composed of aggregate, powder, binder and admixture (material). The phase composition in the matrix is ​​in a non-equilibrium state before use. When used under high temperature, the components in the matrix will follow the phase equilibrium relationship to re-form a new phase equilibrium (that is, obtain excellent performance and in-situ reaction). Therefore, suitable component materials should be selected and the batch design should be optimized to achieve good sintering, volume stability, corrosion resistance and high temperature mechanical properties.

The water demand of kiln mouth castable is generally relatively small, and it needs to be strictly controlled according to the instructions to prevent quality from being affected. Expansion joints are set during the pouring process. Remember not to miss them. One is set every 800mm in the circumferential direction and one is set in the middle when the longitudinal length exceeds 1m (size: L×120mm×5mm). Waterproof measures should be taken at the connection between the castable and the refractory bricks (separated by plywood or plastic paper) to prevent the refractory bricks from getting damp and the castable from losing water. The kiln must not be turned within 12 hours after the pouring is completed.

Chemical indexes of kiln mouth special pouring

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