In the refractory industry, refractory bricks with MgO as the main component and periclase as the main crystal phase are collectively referred to as basic refractory bricks. Basic refractory bricks are mainly used in thermal kilns used in cement, glass, ferroalloy and other industries.
Taking the glass melting furnace as an example, basic refractory bricks are mainly used for heat storage chamber checker bricks. They have high thermal conductivity, long service life, and high volume density, which increases the heat storage capacity of the heat storage chamber. The porosity of basic refractory bricks is low; the thermal expansion coefficient increases linearly with the increase of temperature, which is the largest among various refractory materials. During use, attention should be paid to leaving enough expansion joints.
Basic refractory bricks are non-insulators above 900℃, have good conductivity, and cannot be used as high-temperature insulating materials.
Basic refractory bricks must not be used in gas regenerators, and hydration will occur when in contact with water vapor for a long time at 40~160℃, which will make the brick structure loose and damaged, so they should be kept dry during storage. Before stacking the checker bricks, the regenerator should be dried.
At present, the main varieties of magnesia refractory materials are
01 Ordinary magnesia brick: Made of sintered magnesia as raw material, it is sintered and contains about 91% MgO. It is a magnesia refractory product directly bonded with silicate and is widely produced and used.
02 Directly bonded magnesia brick: Made of high-purity sintered magnesia sand as raw material, it is sintered. It contains more than 95% MgO and is a magnesia refractory product directly bonded between periclase grains.
03 Magnesia silica brick: Made of high-silicon sintered magnesia as raw material, it is sintered and contains 25% to 11% SiO. It is a magnesia refractory product bonded with forsterite.
04 Magnesia chrome brick: Made of sintered magnesia as the main raw material, adding an appropriate amount of chrome ore, and sintered, it contains 8% to 20% Cr2O3. The composition and properties of typical magnesia chrome bricks are shown in Table 2.
05 Forsterite brick: Forsterite refractory material is a refractory material with forsterite as the main crystal phase. It is mostly made of peridotite and dunite as the main raw materials, and the formed products are called forsterite bricks.
06 Magnesia-alumina brick: It is made of sintered magnesia as the main raw material, and an appropriate amount of Al2O3-rich materials are added and sintered.
07 Magnesia-calcium brick: It is made of high-calcium sintered magnesia as the raw material, and contains CaO6%~10%.
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