The main chemical components of magnesium-calcium refractories are MgO and CaO, and the main phases are periclase and calcite. It brings together the advantages of MgO and Ca0.
Compared with magnesia-chromium-based refractories, the technical advantages of magnesia-calcium refractories for the lining of AOD furnaces are:
(1) The raw material resources are abundant, the price is low, and it does not contain chromium, so it will not add chromium inclusions to the molten steel. It is very important not only for chromium-free molten steel, but also for the control of the chromium content of chromium-containing molten steel.
(2) The main components MgO and CaO have high melting points (2800°C and 2570°C, respectively), low vapor pressure, and stable thermodynamic properties.
(3) The combination of MgO-CaO has a larger dihedral angle than the combination of MgO-MgO, which is beneficial to improve the resistance to slag penetration and slag erosion. The thermal shock resistance of magnesium-calcium-based materials is better than that of magnesium-chromium-based materials.
(4) Magnesium-calcium-based materials have strong oxidation-reduction reactivity, even in the AOD furnace and its high temperature.
(5) Magnesium-calcium-based materials exhibit obvious creep properties at temperatures as low as 1260°C. It shows that this type of material has strong resistance to peeling on the hot surface, so it can become a dense material with the greatest corrosion resistance when in use.
(6) Magnesium-calcium refractories contain 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 high Anti-corrosion ability.
(7) The existence of f-CaO can purify molten steel, especially suitable for smelting pure steel.
In recent years, with the rapid development of steelmaking technology, as one of the important refractory materials used in the steel industry, magnesium-calcium refractories are used in steelmaking, continuous casting tundishes, and refining furnaces, especially in the smelting of special steel and pure steel. It is far superior to other refractory materials.
Magnesium-calcium refractory materials are mainly applied to the furnace bottom, the molten pool, and the front and back sides of the converter. Since the 1960s, my country has developed a variety of magnesia-based dolomite fired bricks and implemented a variety of magnesia-calcium refractory materials on the converter, which has achieved good results and improved the life of the converter. Increased steel production.
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