Magnesia carbon brick is a high melting point basic oxide magnesium oxide (melting point 2800 ° C) and a high melting point carbon material which is difficult to be infiltrated by slag as a raw material, and various non-oxide additives are added. A fused magnesia brick, a non-burned carbon composite refractory material combined with a carbon binder. Magnesia carbon brick is mainly used for the lining of converter, AC arc furnace, DC arc furnace, slag line of ladle and so on.

As a composite refractory material, magnesia carbon brick effectively utilizes the strong slag corrosion resistance of magnesia and the high thermal conductivity and low expansion of carbon, which compensates for the most disadvantageous and poor defects of magnesia.

Its main features are: 1 has good high temperature resistance 2 strong slag resistance 3 good thermal shock resistance 4 low temperature creep low

Effect of raw materials on properties of magnesia carbon brick

The main raw materials for the production of magnesia carbon bricks, the quality of magnesia has a very important impact on the performance of magnesia carbon bricks. How to reasonably choose magnesia is the key to producing magnesia carbon bricks. Magnesia has fused magnesia and sintered magnesia, which have different characteristics. Fused magnesia: large crystal grains, less impurities, less silicate phase, high degree of direct grain bonding, and less grain boundaries.

Sintered magnesia: The grain is fine, the impurity is relatively more than the silicate phase, and the direct bonding degree is poor.

For the magnesia raw material, in addition to the chemical composition, high density and large crystallization are required in terms of the structure. Therefore, as the quality index of the magnesia raw material for the production of magnesia carbon brick, the following contents should be examined: 1, magnesium oxide content (purity) 2 The types of impurities are, in particular, the C/S and B2O3 contents, the density of 3 magnesia, the pore diameter, the pore morphology, etc. (sinterability).

The purity of magnesia has a significant impact on the slag resistance of magnesia carbon bricks. The higher the content of magnesium oxide, the less the impurities, the lower the degree of silicate phase division, the higher the degree of direct binding of periclase, the penetration resistance of slag and the melting loss of slag. The juice in magnesia is mainly composed of calcium oxide, silicon dioxide and iron oxide. [1] If the content of impurities is high, especially the compound of boron oxide, it will adversely affect the refractoriness and high temperature performance of magnesia.

The impurities in the magnesia are mainly affected by the following aspects. 1 The direct bonding degree of the reduced magnesite is reduced. 2 The low-melting iron oxide and the magnesium oxide are formed at a high temperature, and the impurities such as silica are at 1500-1800 ° C. The reaction of magnesium oxide with carbon leaves pores to deteriorate the slag resistance of the product.

For the magnesia raw material, in addition to the total amount of impurities, the type of impurities and the relative content of the group of magnesia also have a significant impact. Among them, CaO/SiO2 ratio and B2O3 content have the most obvious influence. Generally, magnesia refractories usually require CaO/SiO2≥2 to improve the high temperature stability of magnesia carbon brick.

The carbon material for preparing magnesia carbon brick is mainly flake graphite.