In order to form the direct combination of crystalline phase to the greatest extent, the content of SiO2 in raw materials shall be as low as possible and the sintering temperature shall be as high as possible. The direct combination degree increases with the decrease of SiO2 content and the increase of sintering temperature. Generally, SiO2 is less than 2%, and the firing temperature is 1700-1800 ℃. The formation of direct bonding is a dissolution precipitation process. Increasing the content of fine powder of chromium concentrate is conducive to the formation of direct bonding magnesium chromium brick. In the presence of silicate, the bonding content between periclase and periclase is strengthened by Cr2O3 and reduced by Al2O3 and Fe2O3. Adding Al2O3 or Fe2O3 to the directly bonded magnesia chrome brick can reduce the silicate melting point, and adding Cr2O3 can improve the melting point. Therefore, the chrome ore with high Cr2O3 content has higher high-temperature strength than the chrome ore with low Cr2O3 content. The higher the Cr2O3 content, the more spinel in and between crystals, the higher the product strength and the stronger the slag resistance.
