Magnesium aluminum spinel has high melting point, low thermal expansion coefficient and thermal conductivity, and is widely used in high temperature industries such as large cement rotary kiln and ladle lining because of its good thermal shock resistance and alkaline slag erosion resistance.

Aluminum magnesia refractory castable is the main component of magnesium oxide castable, magnesium oxide can be added in the form of aluminum magnesia spinel, can also be added in the form of magnesia. In the process of using magnesia, the in-situ magnesia alumina spinel generated by high temperature reaction has the characteristics of low cost, high melting point, good strength, excellent corrosion resistance of high temperature melt and so on. It is widely used in the secondary refining and cement firing process. The formation process of spinel is accompanied by a certain expansion. In order to promote the density of aluminum magnesium spinel refractory castable, also add a trace of water reducing agent and a few additives, and select a quantitative water tank, strict control of castable water, to ensure sufficient molding oscillation time, promote the gas in the castable and the contact of each component, is conducive to baking and use of the matrix response to each other. The production of magnesia Al spinel by electromelting is a typical intermittent operation, and the cooling time of large casting block needs to be extended. The cooling of casting block leads to the uneven microstructure. Due to the faster cooling, the external spinel crystal is smaller than the inner one, and the impurities with low melting point are concentrated in the center. Refractory materials produced by aluminum-rich magnesium spinel are used more in iron and steel production. Two main characteristics increase the application of aluminum-rich magnesium spinel: it can improve the material's high temperature strength and thermal shock resistance and steel slag erosion resistance. The content of spinel in aluminum-magnesia spinel refractories is generally 15%-30% (corresponding to 4%-10% MgO). Recent studies suggest that the life of ladle in aluminum-magnesia spinel refractories fired for ladle is reduced by 60% compared with that of high silicon aluminum-magnesia spinel bricks, which proves that the ideal performance can only be expected from high purity synthetic materials.

Generating spinel in situ of castable can reduce the production cost, but this method also has some shortcomings. When alumina and magnesium oxide react to generate spinel, there is obvious volume expansion. According to the theoretical calculation of relatively dense structure, the volume expansion can reach 13%, but the actual volume expansion is about 5%, which is still too high to avoid the generation of structural cracks. Silica powder additives are often used to promote liquid phase sintering and allow some local deformation to inhibit volume expansion, however, the residual glass relative high temperature strength will have a large impact.