Magnesia brick is an alkaline refractory material with magnesia content above 90% and periclase as the main crystal phase. Generally, it can be divided into two categories: sintered magnesia brick (also known as burnt magnesia brick) and chemically combined magnesia brick (also known as non-burned magnesia brick). Magnesia bricks with high purity and high firing temperature are called direct-bonded magnesia bricks because of the direct contact of the magnesite grains. The bricks made of fused magnesia are called fused and recombined magnesia bricks. Large and medium-sized lime kiln such as rotary kiln, sleeve kiln and shaft kiln. Magnesia brick has the advantages of strong resistance to alkaline corrosion, strong anti-scour ability, good thermal stability, high compressive strength and high load softening temperature. The burnt magnesia brick is made of high-quality sintered magnesia as the main raw material, and the pulp is used as the binder. After kneading and high pressure molding, it is fired in a high temperature tunnel kiln at 1550 ° C or higher. It has good thermal stability, erosion resistance and flaking resistance. It is widely used in industrial kiln such as converter and electric arc furnace as lining refractory material.