In recent years, with the rapid development of steelmaking technology, magnesia-calcium refractory castables are one of the important castables used in the iron and steel industry. Magnesium-calcium refractory castables are used in steelmaking, continuous casting tundishes, and refining furnaces, especially It is far superior to other refractory castables in smelting special steel and pure steel.
Magnesia-calcium refractory castables are mainly applied to the converter at the bottom of the furnace, the molten pool, and the front and rear two large surfaces. Especially in the converter, a variety of magnesia-calcium refractory castables have been comprehensively built and achieved good results. The effect is to improve the furnace age of the converter and increase the output of steel. So what are the reasons for choosing magnesia-calcium refractory castables for steelmaking furnaces?
Lightweight refractory castable
Reasons for choosing magnesium-calcium refractory castable for steelmaking furnace:
1. The main chemical components of magnesia-calcium refractory castables are MgO and CaO, and the main phases are periclase and calcite, which brings together the advantages of MgO and Ca0.
2. Abundant raw material resources, low price, no chromium, so it will not add chromium inclusions to the molten steel. It is very important not only for the chromium-free molten steel, but also for the control of the chromium content of the chromium-containing molten steel.
3. The main components of MgO and CaO have high melting points, 2800°C and 2570°C, respectively, with low vapor pressure and stable thermodynamic properties.
4. The combination of MgO-CaO has a larger dihedral angle than that of MgO-MgO, which is beneficial to improve the resistance to slag penetration and slag erosion. The thermal shock resistance of magnesia-calcium materials is better than that of magnesia-chromium materials.
5. Magnesium-calcium materials exhibit obvious creep properties at temperatures as low as 1260°C. It shows that this type of material has strong resistance to peeling off on the hot surface, so it can become a dense material with high corrosion resistance during use.
6. Magnesia-calcium refractory castable contains highly reactive f-CaO (free calcium oxide can repair the cracks of this type of material and form a very dense and impermeable working surface, so it has a very high Anti-corrosion ability.
7. The price of magnesia-calcium refractory castables is low, generally 1/3~1/2 of magnesia carbon bricks. The CaO in this material reacts with SiO2 in the slag to produce high melting point minerals 2CaO SiO2 and 3CaO SiO2, so that The slag thickens, and it is easy to form a slag layer on the furnace lining, thereby protecting the furnace lining, and at the same time making it easier for the lining working surface to bond with the repairing material, which improves the repairing effect.
8. Magnesia-calcium refractory castables have a series of excellent properties, especially with the function of purifying molten steel. Magnesium-calcium refractory castables with high CaO content have better purification effects on molten steel than those with low CaO content.
9. Selecting high-quality magnesia-calcium raw materials with high purity density, through appropriate additives, optimizing production processes and other links, can improve the high-temperature corrosion resistance, mechanical abrasion resistance and thermal shock stability of magnesia-calcium bricks. Further expand its scope of application and commonality.
Through the above sharing of the reasons why magnesia-calcium refractory castables are selected for steelmaking furnaces, it is not difficult to know that as the performance of magnesia-calcium refractory castables continues to improve, the application field will gradually expand. However, magnesia-calcium refractory castables still have some problems, such as excessive shrinkage during use and easy penetration by slag. Therefore, for a long period of time, magnesium-calcium materials are still used in certain parts of the converter, such as the bottom of some converters, the front and rear two large surfaces, and other parts that are lightly corroded and easy to repair. Now, although the magnesia-calcium refractory castables are basically not used on the furnace lining, the use of CaO-containing gunning materials and front and rear large-surface repair materials are gradually expanding.
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