What should be Paid Attention to when Using Magnesia Refractory Bricks for Rotary Kiln?

Magnesia Refractory Bricks for Rotary Kiln

Magnesia refractory bricks are the most commonly used refractory bricks for rotary kiln linings, such as magnesia-alumina spinel bricks, magnesia-iron spinel bricks, magnesia-chrome bricks, etc. Enterprises should pay attention to the following six aspects when choosing magnesia refractory materials:

① Pay attention to moisture-proof: Magnesia bricks have poor moisture resistance and will deteriorate and crack due to moisture. Magnesium bricks should be placed in a dry place and covered with tarpaulin when entering the factory. Try not to store them before expiration. Unfired magnesia bricks should not exceed 3 months in the rainy season in the south and not exceed half a year in the north. Sintered magnesia bricks can be slightly longer. Prevent throwing and collision during transportation.

② It is best to use magnesia bricks that are consistent with the expansion of the cylinder for the firing zone to avoid large stress in the magnesia bricks and bursting.

③ Because the thermal expansion rate of magnesia bricks is about twice that of clay bricks and high-alumina bricks, leave appropriate brick joints when laying bricks to prevent expansion and cracking when the temperature rises. The seam width between bricks is 2~3mm, and the seam width between rings is 5~6mm.

④ When baking and igniting the kiln, the thermal shock stability of magnesia bricks is poor, and the thermal expansion coefficient and thermal conductivity coefficient are both large. In order to prevent the temperature from rising too fast and the fire bricks from bursting, a corresponding kiln baking system should be in place. That is, the kiln heating speed is slow, preferably 120℃/h, and the fastest is no more than 200~250℃/h. Wait until the moisture attached to the kiln lining is completely dried, and then spray coal to gradually heat up.

⑤ Hang the kiln skin and protect the "kiln skin" to avoid exposed bricks and red kilns.

⑥ Do a good job of insulation when the kiln is temporarily stopped. Magnesium bricks have poor thermal shock stability. When the kiln is temporarily stopped to repair equipment or to repair refractory bricks in other parts, the two-end wind must be turned off to gradually reduce the temperature in the kiln, especially when the "kiln skin" is not good or there are exposed bricks. Insulation is more important. If you plan to stop the kiln, you can hang the "kiln skin" in advance to protect the magnesia bricks.