The influences of raw material on magnesia carbon brick performance

Magnesia carbon brick series used for the electric furnace are made by adoption of fused magnetite, high-purity magnesium sand and graphite as principal raw material, through high-pressure molding and low-temperature treatment. 

 magnesia carbon brick refractory alkaline oxide is magnesium oxide (melting point 2800 ℃) and difficult to infiltrate a high melting point slag carbon material as a raw material, adding a variety of non-oxide additives. Made in conjunction with carbonaceous binding agent is not charcoal refractory composites. MgO-C is mainly used for the converter, AC arc furnace, DC arc furnace lining, ladle slag lines and other parts.

MgO-C brick composite as a refractory material, the effective use of high thermal conductivity and strong resistance to slag erosion ability of magnesia and carbon and low expansion, the biggest drawback is compensated magnesia poor chipping resistance.

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

MgO-C material impact on performance

The main raw material for the production of magnesia carbon bricks properties, magnesia quality will have a crucial impact on the performance of MgO-C, magnesia how reasonable choice is the key to the production of MgO-C. There magnesia and fused magnesia sinter magnesia, which have different characteristics. Fused magnesia: grains, less impurities, less silicate phase, a high degree of direct bonding grain, less grain boundaries.

Sintered magnesia: fine grain impurities silicate phase relative called more directly the degree of integration is poor.

For magnesia raw materials, in addition to the chemical composition, in terms of organizational structure, also called high density and large crystal, therefore, as magnesia magnesia carbon bricks manufacturers
 produced raw material quality indicators used, the following should be investigated:

1, magnesium oxide content (purity)
2, the type of impurity, particularly .C / S and B2O3 content
3, magnesia density, pore size, pore morphology (sinterability).

Purity magnesia has a major influence on slag resistance of MgO-C. Magnesium oxide content is higher, relatively fewer impurities and reduce the degree of segmentation silicate phase, periclase directly bonded to improve the degree of melting loss resistance to slag penetration and slag increased. Magnesia in the juice mainly calcium oxide, silica, iron oxide, if the impurity content is high, especially compounds of boron oxide, magnesia refractoriness and high temperature will adversely affect the performance.

Magnesia of impurities separated at mainly affect several aspects of a periclase reduce the degree of direct bonding at a high temperature of magnesium oxide 2 forming a low-melting material 3 iron, silica and other impurities in the 1500-1800 ℃, the first magnesium oxide react with carbon, leaving pores so that slag resistance of the article deteriorates.

For magnesia raw materials, in addition to the total amount of impurities, the type of impurity and magnesia performance relative content team also have a significant impact. Which affect the CaO / SiO2 ratio and B2O3 content in the most obvious, the general magnesia refractories usually require CaO / SiO2≥2 MgO-C in order to improve the high temperature stability
Preparation of MgO-C materials mainly carbon flake graphite