MgO-C brick is a kind of high melting point basic oxide MgO (melting point 2800 ℃) high melting point carbon material which is difficult to be infiltrated by slag. It is a kind of unburned composite refractory made of magnesia carbon brick carbon binder. Magnesia carbon brick is mainly used for lining of converter, AC arc furnace DC electric arc furnace, slag line of ladle, etc.

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

Its main characteristics are: 1. Good high temperature resistance; 2. Strong slag resistance; 3. Good thermal shock resistance; 4. Low high temperature creep

Effect of raw materials on properties of magnesia carbon brick

The quality of magnesia has a very important influence on the performance of magnesia carbon brick. How to choose magnesia reasonably is the key to produce magnesia carbon brick. Magnesia includes fused magnesia sintered magnesia, which have different characteristics. Fused magnesia: large grains, less impurities, less silicate phase, high degree of direct combination of grains, less grain boundaries.

Sintered magnesia: the grain size is fine, the impurity silicate phase are relatively more, the direct bonding degree is poor.

For magnesia raw materials, in addition to chemical composition, high density large crystallization are also required in microstructure. Therefore, as the quality index of magnesia raw materials for producing magnesia carbon bricks, the following contents should be investigated: 1. MgO content (purity) 2. Impurity types, especially. C / s B2O3 content 3. Density, pore size pore morphology of magnesia (sinterability).

The purity of magnesia has great influence on slag resistance of magnesia carbon brick. The higher the MgO content is, the less impurities are, the lower the degree of silicate phase separation is, the higher the direct binding degree of periclase is, the slag penetration resistance slag melting loss ability are improved. There are mainly calcium oxide, silicon dioxide iron oxide in magnesia. If the impurity content is high, especially the compound of boron oxide, the refractoriness high temperature performance of magnesia will be adversely affected.

The impurities in magnesia mainly have the following effects: 1. Reduce the direct binding degree of periclase; 2. Form low melting substance with magnesium oxide at high temperature; 3. Impurities such as iron oxide silicon dioxide react with carbon prior to magnesium oxide at 1500-1800 ℃, leaving pores, which makes the slag resistance of products worse.

For magnesia raw materials, in addition to the total amount of impurities, the type relative content of impurities also have a significant impact on the properties of magnesia. Cao / SiO2 ratio B2O3 content have the most obvious influence. CaO / SiO2 ≥ 2 is usually required to improve the high temperature stability of magnesia carbon brick

The main carbon material for preparing MgO-C brick is flake graphite