Al2O3-MgO-C Bricks for the Secondary Refining Furnace
Al2O3-MgO-C refractories are developed on the basis of high-performance magnesia-carbon and alumina-carbon refractories. It is a substitute product for high alumina brick and dolomite brick ladle lining. In contrast, this kind of alumina magnesia carbon brick composed of two kinds of alkaline and acid-base refractory oxides not only has excellent chemical and thermodynamic stability, but also has excellent thermal and mechanical properties. Al2O3-MgO-C series refractory materials are divided into alumina-magnesia carbon bricks and alumina-magnesia spinel castables.
Alumina-magnesia-carbon bricks (https://rsrefractoryfirebrick.com/alumina-magnesia-carbon-bricks/) are non-burned bricks made of special grade bauxite clinker with an Al2O3 content of more than 85% as aggregate, adding fine magnesia powder and flake graphite, and using phenolic resin as a binder. Used as the inner lining of the refining ladle outside the furnace, its main components, Al2O3 and MgO, can react to form alumina-magnesia spinel with volume expansion. The slag resistance and thermal expansion rate of bricks increase with the increase of MgO content. Due to thermal expansion, the brick joints of the lining are reduced and the lining structure is dense. However, if the MgO content is too high, the expansion rate is too large, which can cause cracking and damage of the bricks. In order to adjust and control the formation and expansion effect of spinel during use, the pre-synthesized alumina-magnesia spinel clinker is used as raw material to replace part of bauxite clinker and magnesia when making bricks. Products manufactured by this method are also called alumina-magnesia spinel carbon bricks.
Alumina-magnesia spinel castables were developed in the mid-1990s, and there are two types. One is a castable that uses fused corundum, sintered corundum, high-purity fused magnesia, high-purity alumina-magnesia spinel as raw materials, and a combination of pure calcium aluminate cement, high-purity SiO2, and Al2O3 powder. It has excellent anti-erosion and anti-permeability properties and can be used on various large ladle. The other is bauxite clinker-based aluminum-magnesium spinel castable. It is a natural raw material based in my country, with bauxite clinker as aggregate, castable combined with fused magnesia, spinel powder, and calcium aluminate cement. Mainly used for lining of medium and small steel ladle.
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