Some information about magnesia aluminum bricks

January 18, 2019

Magnesia aluminum brick is a spinel-type alkaline refractory product containing about 85% MgO. The replacement of magnesia-chrome bricks in glass furnace regenerators as lattices has good corrosion resistance. In general, magnesia aluminum bricks are divided into two types, one is MA as the binding phase, MA is formed during firing, and dispersed between large particles of magnesia; the other is pre-synthesized MA particles, added to the ingredients. 

magnesia aluminum bricks

(1) MA combined magnesia aluminum bricks

The content of Al2O3 has an important influence on the microstructure and properties of magnesia aluminum bricks with magnesium-aluminum spinel as the main binding phase. When the content of Al2O3 is 15%~20%, a continuous combination of magnesia aluminum spinel is formed in the bricks. When the content of Al2O3 is less than 10%, MA is distributed in the shape of an island of periclase.

(2) Pre-synthesized MA magnesia aluminum bricks

The synthesis reaction mechanism of MA is ion diffusion and can be carried out at a relatively low temperature (1050℃~ 1300℃). As the temperature increases, the reaction is intensified. At about 1500℃, the synthesis of MA is quite complete, forming a sufficiently complete MA crystal. However, to obtain a highly dense MA composition, sintering at a higher temperature is required.

For the production of pre-synthesized magnesia-aluminum bricks, MA can be used to synthesize coarse particles, magnesia clinker is used as fine powder, or two kinds of raw materials can be used in equal amounts. Usually high-purity fused magnesite is used. If more SiO2 is brought into the bricks, the high temperature performance will be affected, thus losing the meaning of pre-synthesized MA.