The "magnesia chrome brick" of new building materials

Magnesia chrome bricks are made of magnesia carbon bricks (melting point 2800 ℃) for high melting point alkaline oxide magnesium oxide ladles and high melting point carbon materials that are difficult to be wetted by slag as raw materials for electric furnaces, with various non oxide additives added. The unburned carbon composite refractory is made by combining the carbon binder. Magnesia carbon bricks are mainly used for lining of converter, AC arc furnace and DC arc furnace, slag line of ladle, etc.

As a composite refractory, magnesia chrome brick effectively utilizes the strong slag corrosion resistance of magnesia and the high thermal conductivity and low expansion of carbon, and compensates for the poor spalling resistance of magnesia.

There are four main characteristics of magnesia chrome bricks, namely, good high temperature resistance; Strong slag resistance; Good thermal shock resistance; High temperature creep is low.

Effect of raw materials on properties of magnesia chrome bricks

The quality of magnesia, the main raw material for producing magnesia chrome bricks, has a very important influence on the performance of magnesia carbon bricks. How to reasonably select magnesia is the key to producing magnesia carbon bricks. Magnesia includes fused magnesia and sintered magnesia, which have different characteristics.

Fused magnesia: large grains, few impurities, few silicate phases, high degree of direct grain bonding, and few grain boundaries.

Sintered magnesia: fine grains, relatively more impurities and silicate phases, poor direct bonding.

In addition to chemical composition, magnesia raw materials also require high density and large crystallization in terms of structure. Therefore, as the quality index of magnesia raw materials for production of magnesia carbon bricks, the following contents should be investigated:

1. Magnesium oxide content (purity)

2. Type of impurities, especially C/S and B2O3 content

3. Density, pore diameter and pore morphology of magnesia (sintering property)