Sintered magnesia brick, magnesium aluminum spinel brick

The raw material of magnesia brick is mainly magnesite, and its basic component is MgCO3. After high temperature calcination, it is crushed to a certain particle size to become sintered magnesia. Electric furnace magnesia carbon brick magnesia is widely used as a material for repairing furnaces, beating materials, and containing less magnesia (ω(CaO)<2.5%, ω(SiO2)<3.5%) as a raw material for the production of magnesia bricks. China's magnesium reserves and production are among the highest in the world.

Magnesia bricks are divided into sintered magnesium bricks and chemically combined magnesium bricks according to their different production processes. The sintered magnesia brick is made of calcined magnesia with appropriate particle size ratio, added with brine (MgCl2 aqueous solution) and sulfite pulp waste liquid as a binder, and is formed by pressure molding at a high temperature of 1550~1650 °C. The chemically-bonded magnesia brick is not subjected to the calcination process. After the sintered magnesia is proportioned according to the particle size ratio, an appropriate amount of mineralizer and binder are added, and the mixture is pressed and formed, and after drying, it is a finished product. The chemically bonded magnesia bricks have lower strength and are not as good as sintered magnesia bricks, but they are cheaper than half the price of sintered magnesia bricks. It is used in areas where performance requirements are not too high, such as furnaces and soaking furnace bottoms.

Magnesia brick is an alkaline refractory material. It has strong resistance to alkaline slag, but it can not resist the erosion of acid slag. It can react with silica brick, clay brick and even high alumina brick at 1600 °C. The refractoriness of magnesia bricks is above 2000 °C, but its load softening point is only 1500~1550 °C. Moreover, the temperature interval from the beginning of softening to 40% deformation is very small, and the thermal stability of only 30~50 °C magnesia bricks is also poor, which is an important reason for the damage of magnesia bricks.

On the heating furnace and the soaking furnace, the magnesia brick is mainly used for paving the surface layer of the bottom of the furnace and the lower part of the furnace wall of the soaking furnace, which can resist the erosion of the scale.