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Properties of magnesium calcium refractory for AOD furnace lining

The AOD furnace uses high-quality, high-purity, and hydration-resistant magnesium-calcium synthetic materials with controllable components. Its main components are MgO and CaO, so the properties of magnesium-calcium refractories are determined by the properties of these two substances. Both of these substances have a face-centered cubic structure: MgO has good melting resistance, and its melting point is as high as 2825 °C, but its thermal shock resistance is not good, and it is also easily damaged by slag. Infiltration, C reacts with MgO as follows at 1600 °C:

C+MgO→Mg+CO
This will lead to weightlessness and will also cause damage to the magnesia-carbon brick. The melting point of CaO is also very high, but its thermodynamic properties are stable, its vapor pressure is low at high temperature, its thermal expansion coefficient is small, and its resistance to peeling and slag erosion is strong. Because CaO also has strong chemical activity, it can purify molten steel and remove S, Al, P, etc. Therefore, MgO and CaO fired into magnesium-calcium refractories will have many excellent properties:

(1) Purify the molten steel composition.

Free CaO has strong activity and can chemically react with impurity elements such as S, P, and Al in molten steel, and the reaction product floats into the slag, which is not available in other materials.

(2) Hang the kiln skin tightly.

The CaO in this material can react chemically with C2S in the cement to form C3S. Both of these sulfide silicates have high melting points, which can make the kiln skin fast.

(3) High temperature resistance.

Both CaO and MgO have high melting points, and can also form preferential solid solutions under high temperature conditions. When these two substances exist at the same time, they will not form low-melting eutectic compounds, so their high temperature resistance will be very strong.

(4) Strong stability in vacuum high temperature environment.

The quality of high-purity magnesia dolomite brick is better than that of magnesia-chrome brick, its weight loss rate is low, and it can be very stable in high temperature vacuum environment.

(5) High cost performance.

The price of AOD magnesia-carbon bricks is twice as high as that of dolomite refractories, so many steel mills use inexpensive magnesia-calcium lining materials to reduce the cost of steel.

(6) Anti-slag performance.

As the alkalinity increases, the corrosion resistance of magnesia-calcium refractories to slag is significantly improved, and the slag infiltrated into the brick reacts with CaO to produce high melting point compounds C2S and C3S, and the wetting angle increases accordingly. , the viscosity of the slag increases, and it is difficult for the slag to continue to penetrate into the interior of the refractory brick.

(7) Environmental pollution is small.

Magnesium-calcium refractories are very environmentally friendly, and the environmental pollution is very small.

Wanhao is a manufacturer who is specialized in designing various kinds of furnace and making refractory products for electric furnace, ladle, tundish, blast furnace, AOD furnace, IF furnace, etc.


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