Advantages of Dolomite Bricks in Large-Scale Use in High-Temperature Zones of Cement Kilns

Dolomite bricks are primarily made from dolomite. They are made from a single raw material: sintered dolomite (MgO·CaO). The theoretical composition of the pure raw material is 42% MgO and 58% CaO; the combined content of SiO₂, Al₂O₃, and Fe₂O₃ is less than 3%. Based on its main components, the bricks are easily digestible. Unwaterproofed bricks typically break down into fragments within two to three weeks, creating significant challenges for their use. However, advancements in packaging and impregnation technology mean that manufactured dolomite bricks can be stored for up to a year and reused without issue.

Dolomite Bricks for Cement Kilns

Dolomite's greatest advantages are its price advantage and excellent adhesion to kiln linings. Due to its excellent chemical resistance, dolomite bricks are widely used in the high-temperature zones of cement kilns.

Advantages of Using Dolomite Bricks in Cement Kilns

(1) Excellent kiln lining performance.

Because dolomite bricks are in a high-temperature state, the liquid phase of cement clinker will corrode the surface of the brick body. When the temperature rises to 1450℃, the f-CaO in the brick will react with the calcium sulfate in the cement clinker, thereby forming a protective layer on the surface of the brick. Because the melting points of C2S and C3S are relatively high, the film is not easy to disappear, so the kiln lining protective layer formed on the surface of the brick is relatively stable.

(2) Excellent corrosion resistance.

Because the bricks contain f-CaO, a relatively strong protective film kiln lining can be formed on the surface of the brick. The newly formed kiln lining can effectively prevent the liquid phase in the cement clinker from diffusing into the brick body of the dolomite brick, reducing the corrosion and spalling of the refractory bricks. Moreover, because the newly formed kiln lining is thick, the temperature of the refractory bricks is reduced. As a result, the chemical corrosion and heat load of the refractory bricks are reduced, thereby increasing the application time of the dolomite bricks.

(3) The heat loss of the cement kiln body is reduced.

Because a thick protective film forms on the brick surface, its temperature is lowered. Less heat is dissipated through the inner walls of the rotary kiln, improving economic efficiency and reducing energy consumption. However, weak hydration resistance is the most serious weakness of dolomite bricks. During the preparation and delivery processes, they come into contact with air, reacting with water vapor and causing severe hydration. Furthermore, their poor thermal shock resistance often causes large cracks in cement rotary kilns during intermittent use, leading to damage. Key solutions for improving thermal shock resistance include improving the firing system, selecting an appropriate particle size distribution, and adding appropriate additives.