Spinel Refractory Materials

Spinel refractory materials are an important class of neutral or slightly alkaline refractory materials. They are widely used in high temperature industrial furnaces, open-hearth, electric furnace, ladle refining furnace, cement kiln, glass furnace regenerator and smelting furnace.

Spinel refers to a class of minerals with the same structure, expressed as AO·R2O3( or AR2O4). Wherein A presents divalent element ions such as Mg2+, Fe2+, etc.; R is a trivalent element, such as Al3+, Fe3+, Cr3+, etc.. They mostly exist in the form of isomorphous solid solution. All spinel forms a solid solution by expansion of lattices. According to the raw material and chemical composition, spinel refractory materials can be divided into chrome brick, chrome-magnesia brick, magnesia-chrome brick and magnesia-alumina spinel refractories. 

 

1) Chrome spinel refractories

These refractory materials include chrome brick, chrome magnesia brick and magnesia-chrome brick. It is composed of chrome spinel (or solid solution) and periclase as the main mineral composition. They are made of chromium ore, caustic magnesite or dunite. Chromite is directly used to make bricks. The ground chromite is mixed with 5% light burning magnesium powder. then the mixture is molded, dried and fired into chrome bricks at 1550℃. 

 

2) Magnesia-alumina spinel refractories

Magnesia-alumina spinel, also called spinel, is expressed as MgO·A12O3, containing 28.3% MgO and 71.7% A1203. Its melting point is 2135℃. Compared to magnesia-chrome bricks, magnesia-alumina spinel has advantages in excellent corrosion resistance to reducing atmosphere, free CO2, free SO2/SO3 and free K2O / Na2O and good thermal stability and wear resistance. 

 

Spinel refractory can be divided into three categories: periclase spinel refractories (A12O3<30%), spinel periclase refractories (A12O3 30%-68%) and spinel refractory materials (Al2O3 68%-73%).