Magnesia aluminum refractories of Basic Refractories:
Ladle steel industry is an important and indispensable equipment, as ladle lining, several major changes. Used to be traditional by sintering of clay
refractory brick and third class alumina brick, the
refractory material shows poor chipping resistance and corrosion resistance during use, low life, an average of only 10 times, dried treatment can only reach about 20 times. With the development of steelmaking technology, refining the molten steel to improve the outer retaining ladle lining
insulating castable requirements in the early years of the 20th century that is, once the application as a whole
Cast Mg-Al quality ladle lining material. This lining integrity, and significantly improve the service life, but there are baked ladle long time, there are more serious dregs phenomenon for medium and small mills no special equipment most circumstances, unpacking difficult. To compensate for this deficiency, then the successful application of aluminum-magnesia unfired brick. The lining brick building is easy to assemble, baking time is short and easy unpacking, but still easy to kill slag and chipping resistance is poor. On this basis, in order to overcome the problem of aluminum-magnesia unfired brick ladle lining easy cat slag around the corner late he has not developed the aluminum-magnesia carbon brick, replacing the aluminum-magnesia unfired brick. The material combines the properties of aluminum-magnesia material and carbonaceous material. The main advantages of aluminum-magnesia carbon brick does not have: no cracks between the blocks melt loss, has good resistance to thermal shock resistance and slag ability to overcome the structural steel and slag penetration flaking, significantly improved service life and so on. Because the article is not burning or low-temperature firing, save energy, reduce costs, economic efficiency is very obvious, it attracted people's attention.
China advised in the 20th century, it began with bauxite and magnesite (or light burned MgO) magnesia aluminate spinel raw materials research. In recent years, also carried out a series of studies preparation of magnesia spinel products combine technology, achieved a lot, but the performance has been excellent in high purity products suffer from a high degree of firing is very limited. Domestic activity spinel powder was used. The ultra-high temperature firing process overseas (1 850c) down to 1 660C. But for the average coal-fired furnace refractory general terms, it is still difficult to achieve. To this end, the domestic refractory experts and scholars made active magnesia aluminum gum as a binding agent, was studied with the active Mg-Al gum as binding agent and high-purity
magnesia carbon brick magnesia brick spinel combination of performance, the use of magnesia aluminum adhesive activity, both make excellent performance products fired at 1 550 ℃, such as the advanced products in firing ordinary refractory kiln plant in Shanghai possible.
Through active lime kiln back to actual production, research and development of magnesia aluminate spinel unfired brick. Use show, developed spinel unburned brick in the active lime kiln firing service life of more than one year. For a long time, directly from the dry combination of
MGO brick manufacturers with excellent slag resistance and corrosion resistance, it is used in large alkaline rotary kiln Pu left. Currently the most widely used range of the steel industry, most of the largest refractory Mg - Al system is unshaped refractory, accounting for about 85% of the unshaped refractories of total production, it is widely used in the converter, ladle, iron package, furnace and blast, virtually all metallurgical thermal equipment.
Spinel has a high melting point, small thermal expansion, low thermal stress, thermal vibration stability, and it has a more stable chemical properties of alkaline slag has a strong resistance, aluminum-magnesia do not burn brick core point to be used, is one of the key substances to improve life. Due to the gradual maturity in recent years, synthetic spinel technology, the use of synthetic spinel materials directly produce good ladle brick as possible, so that it can significantly improve the properties.
Quality spinel is one of the key issues related to the inter-spinel bricks can achieve the proper effect. By introducing the screening laboratory tests and related information, the magnesia-rich spinel 20% to 30% of its corrosion resistance, structural spalling resistance and thermal shock properties are better. But ladle conditions are more factors in the production operation, the amount of added spinel requirements should be 30% to 40% is more reasonable. Therefore, in brick-making process, in addition to producing a good artificial spinel added, we must also note the addition of fused magnesia powder and alumina powder, so that the secondary spinel regenerated during use. Thereby improving bricks tomb of quality performance parts for the control of harmful impurities in particular low-melting material was Na20 and K2O content, the choice of raw materials need special attention exhausted.
Spinel (also known as spinel) has the formula MgO-Al2O3, containing Mg0 was 28.3%, Al2O3 71.7%. Spinel is only Mg0-Al2O3 binary system phase diagram of an intermediate compound, melting at 2 135 C.
