Improve the thermal stability of magnesia bricks. Magnesium bricks with magnesia-aluminum spinel as the main mineral are produced by adding alumina to the ingredients. The advantage of magnesia-spinel bricks is that they have good thermal stability. They will react with clinker during use, and then in the bricks A very thin calcium aluminate protective layer is formed on the surface, making it difficult for the night body to penetrate, and its anti-flaking performance is better than that of directly bonded magnesia-chromium bricks.