Corundum-Mullite Burner Brick

Corundum-Mullite Burner Brick

Improvement of burner brick material The choice of corundum-mullite refractory castables to make burner brick prefabricated parts has the following advantages:

• 1: The main crystal phases of corundum-mullite refractory castables are corundum and mullite. The former has a high melting point of 2050℃, hardness and strength, can resist high temperature and airflow erosion, and has excellent high temperature wear resistance. The melting point of mullite is also relatively high at 1840℃, and its characteristic is a small thermal expansion coefficient. The crystal has a needle-column mosaic structure and has good thermal shock resistance. The composite refractory castable of corundum phase and mullite phase has the advantages of both, which can effectively resist the erosion of burner bricks by flame hot air flow. It can withstand harsh thermal shock environments and prevent burner bricks from breaking.
• 2: There is no hydration problem with corundum mullite refractory castables, and the construction is less affected by the environment. The construction conditions are not demanding, and the pouring, curing and heat treatment can be carried out at the material supplier, so the quality is easy to be guaranteed. It will not hydrate and crack during construction and baking.
• 3: The burner brick is a special-shaped brick, which is not easy to be machine-pressed. The pouring method is easy to achieve integral or split forming, and realize precise control of shape and size. The critical particle size of machine-pressed bricks is limited, generally 5 mm, while the critical particle size of castables can be as large as about 20 mm, which is conducive to the stability of the structure and improves the resistance to thermal shock.
• 4: When the burner brick is in use, the gas (or fuel oil) is sprayed into the furnace, and the CaO dust in the furnace is not easy to adhere to the burner cavity, and the reaction of CaO and Al2O3-SiO2 materials will not occur. Even if a small amount of CaO adheres to the burner brick, the Al2O3 content in the burner brick is high (greater than 75%), while the content of SiO2 and CaO is relatively low. According to the A12O3-SiO2-CaO ternary phase diagram, the temperature of the reaction is about 1500℃. It can be considered that the solid phase reaction of Al2O3-SiO2-CaO is not easy to occur at the working temperature of the lime kiln.

The magnesia refractory bricks used in the burners of general sleeve lime kilns are prone to fracture after more than a year of use, which makes the service life of the burner bricks out of sync with the life of the kiln body. That is, the burner of the sleeve kiln is prone to fracture. By analyzing the cause and reproducing the prefabricated burner bricks made of corundum mullite refractory castables suitable for the burner of the sleeve kiln according to the combustion process of the lime kiln calcining zone and the structure of the lining refractory material, the problem of burner brick fracture is effectively solved. And practice shows that the service life of the corundum mullite burner bricks is synchronized with the life of the kiln body.