The classification and production process of mullite refractory

The chemical formula of mullite is 3AlO3 2SiO2, and the theoretical composition is Al2O3 71.8%, SiO2 28.2%, which is AI2O3-SiO2.

The only stable compound in the binary system and the most widely studied crystal phase. Its melting point is (1890±90) °C, and it is crystallized with an orthorhombic crystal structure. The crystal structure is developed in the direction of the aluminum-oxygen octahedron sharing AlO6 parallel to the C axis, and the lateral direction is (Si, Al)O4 tetrahedron and AlO6 octahedron. A chain-like silicate mineral phase is connected by a shared edge. With the increase of Al3+ content, more oxygen vacancies will be generated in the crystal lattice, its structure has large voids and is relatively loose.

The mullite raw materials used in the refractory industry are generally artificially synthesized, and there are few valuable natural mullite ores. Mullite refractories refer to refractories with synthetic mullite as the main raw material and mullite as the main crystal phase. The classification and production process is as follows:

1. Sintered mullite products 2. Cast mullite products

The production process of refractory materials is similar to that of high aluminum products. The process points that need to be paid attention to are: accurate batching (particle gradation, ratio of aggregate and fine powder), uniform mixing, high-pressure molding, and full sintering. Firing temperature: when sintered mullite is used as aggregate1550 ~ 1600 ℃; >1700 ℃ when using fused mullite as aggregate.