There is a process of electric melting and re bonding (semi re bonding) magnesia chrome brick

3. Electric fusion and rebinding (semi rebinding) magnesia chrome brick:

Usually, the magnesia chrome bricks made of fused magnesia chrome sand are called rebonded magnesia chrome bricks, and the products with partially fused magnesia chrome sand are called semi rebonded magnesia chrome bricks.

Based on the characteristics of direct bonding of high-temperature crystalline phase of microstructure, the re bonded and semi re bonded magnesia chrome bricks are the direct bonding bricks with higher direct bonding rate.

Due to the characteristics of low impurity content and high temperature (ultra-high temperature) firing, both direct bonded magnesia chrome bricks and semi bonded (semi bonded) magnesia chrome bricks are also called high temperature fired (ultra-high temperature fired) magnesia chrome bricks.

The use of synthetic magnesia chrome sand is the technological basis for producing re bonded and semi re bonded magnesia chrome bricks.

Direct bonding and secondary spinelization are the theoretical basis for the production process of magnesia chrome refractories.

The so-called secondary spinel is the spinel formed by high temperature treatment or chemical reaction, which is different from the original chrome ore. There are three main types:

(1) Intercrystalline spinel - liquid-phase crystallization.

Silicate phase in magnesia chrome brick mainly comes from gangue in chrome ore.

The distribution of gangue in chrome ore is uneven, so the liquid phase formed after melting is difficult to be evenly distributed, and will be locally enriched. After the chromite surface dissolves in the liquid phase, most of the re precipitates are idiomorphic secondary spinels.

(2) The transition constitutes spinel.

Transition composition spinel refers to the reaction zone formed between chromite or spinel and periclase, which is the transition zone of gradual composition. Such reaction zone contributes the most to direct bonding. Some parts realize interphase "fusion", and some show microcracks.

(3) Desolved spinel.

Desolvation phase in periclase crystal is the third form of spinel, which has no effect on direct combination between phases, but plays an important role in changing the properties of periclase solid solution, and can improve the corrosion resistance of acid medium; Improved thermal shock resistance and toughness.