Performance and Use of Magnesia Brick
Performance and use of magnesia bricks
Magnesia bricks are an alkaline refractory material with magnesia content above 90% and periclase as the main crystal phase. Generally, it can be divided into two categories: sintered magnesia brick (burnt magnesia brick) and chemically combined magnesia brick (non-burned magnesia brick).
Magnesia bricks have high refractoriness, good resistance to alkaline slag, high starting temperature of load softening, but poor thermal shock resistance. The sintered magnesia brick is made of brick and magnesia bricks. After being crushed, compounded, kneaded and formed, it is fired at a high temperature of 1550~1600 °C. The firing temperature of high-purity products is above 1750 °C. The non-burned magnesia brick is prepared by adding a suitable chemical binder to the magnesia, mixing, forming and drying.
The linear expansion rate of magnesia bricks at 1000-1600 °C is generally 1.0%-2.0%, and is similar or linear. In refractory products, the thermal conductivity of magnesia bricks is second only to carbon-containing bricks, which increases with temperature. reduce. Under the condition of water cooling at 1100 ° C, the thermal shock of the magnesia brick is only 1 or 2 times. Magnesia bricks have strong resistance to CaO and ferric alkaline slag, but have weak resistance to acidic slags such as SiO2.
Therefore, it cannot be directly contacted with silica bricks during use, and is generally separated by neutral bricks. At normal temperature, the conductivity of magnesia bricks is very low, but at high temperatures, its conductivity cannot be ignored. The performance of magnesia bricks is greatly different due to the different raw materials, production equipment and process measures.
Magnesia bricks are widely used in steelmaking lining, iron alloy furnaces, mixed iron furnaces, non-ferrous metallurgical industrial furnaces, limestone kiln for building materials, and lattice storage of glass industrial regenerators due to their high temperature performance and strong resistance to alkaline slag. High temperature calcining kiln and tunnel kiln for heat exchanger and refractory industry.