Mullite insulation brick is a high-alumina refractory material with mullite as the main crystal phase. Generally, the alumina content is between 40% and 70%. The working temperature ranges from 1300°C to 1600°C. The advantage of mullite lightweight insulation bricks is that they can be exposed to flames and can be directly used as the lining of high-temperature kilns. Mullite lightweight insulation brick is a refractory insulation material widely used in new industrial kilns and high-temperature equipment.