Characteristics of unburned magnesia chrome bricks

In order to obtain magnesia chrome bricks with high direct binding rate, the content of CaO in raw materials should also be reduced, because it is also the main source of increasing the content of silicate phase in magnesia chrome bricks. Fortunately, the content of CaO in most chromites is not very high.

Even if the content of SiO2 and CaO in chromite is the same, the effect of different types of chromite (i.e. different Al2O3/Cr2O3 ratio and Fe2O3/Cr2O3 ratio) on the properties of magnesia chrome brick is very obvious. The study on the influence of Cr2O3, Al2O3 and Fe2O3 in magnesia chrome bricks on dihedral angle between adjacent periclase grains shows that the bond between periclase and periclase will be strengthened by Cr2O3, but weakened by Fe2O3 and Al2O3; The increase of Fe2O3 and Al2O3 decreased the melting point of silicate phase. Using chromite with high content of Cr2O3 (Al2O3 and iron are reduced correspondingly) can obtain lower content than using Cr2O3

Chromite has higher high temperature strength. However, the price of chromite with high Cr2O3 content is expensive. In actual production, a compromise scheme can be adopted according to the requirements for brick performance. The typical physical and chemical properties of burnt magnesia chrome bricks are: MgO 52.73%, Cr203 18.08%, SiO2 5.0%, apparent porosity 10.9%, bulk density 3.08g/cm3, compressive strength 58MPa, load softening temperature 1520~1530 ℃.