Advantages of Using Dolomite Bricks Extensively in the High-Temperature Zone of Cement Kilns

Dolomite bricks are primarily composed of 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 total amount of SiO2, Al2O3, and Fe2O3 is less than 3%. Based on its main components, this brick is prone to hydration. Without waterproofing treatment, dolomite bricks typically decompose into fragments within 2-3 weeks. This presents significant challenges to their use. However, thanks to advancements in packaging and impregnation technologies, finished dolomite bricks can be stored for up to a year before reuse.

Advantages of Using Dolomite Bricks

The biggest advantages of dolomite are its price advantage and good adhesion to kiln linings.

Due to their good resistance to chemical corrosion, dolomite bricks are widely used in the high-temperature zones of cement kilns.

The advantages of dolomite bricks are as follows:

(1) Excellent kiln coating performance:

At high temperatures, the liquid phase of cement clinker erodes the surface of dolomite bricks. When the temperature rises to 1450℃, the f-CaO in the brick reacts with the dicalcium sulfate in the cement clinker, forming a protective layer on the brick surface. Since C2S and C3S have relatively high melting points, the film does not easily disappear, resulting in a relatively stable kiln coating protective layer on the brick surface.

(2) Excellent corrosion resistance:

The presence of f-CaO in the brick allows for the formation of a strong film on the brick surface, protecting it from kiln corrosion. The newly formed kiln coating effectively prevents the liquid phase in the cement clinker from diffusing into the interior of the dolomite brick, reducing corrosion and spalling. Furthermore, the thicker newly formed kiln coating lowers the temperature of the refractory brick, reducing chemical corrosion and heat load, thus extending the service life of the dolomite bricks.

(3) Reduced heat loss in the cement kiln body:

A thick protective film forms on the surface of the bricks, lowering their temperature. Less heat dissipates through the inner wall of the rotary kiln, thus improving economic efficiency and reducing energy consumption.

Weak resistance to hydration is the most serious weakness of dolomite bricks. During preparation and output processes, they come into contact with air and react with water vapor, leading to severe hydration. Furthermore, poor thermal shock resistance often results in large-area cracks in the cement rotary kiln during intermittent use, causing damage.

The main solutions to improve thermal shock resistance include: improving the firing regime, selecting appropriate particle size distribution, and adding suitable additives.