Fused magnesia is a general term for the products of magnesia raw materials such as magnesite that have been treated at high temperature to the degree of sintering. Using high temperature equipment such as shaft kiln and rotary kiln, one-step calcination or two-step calcination process, magnesia fired with natural magnesite as raw material is called sintered magnesia; fused magnesia manufacturers use magnesite as raw material to pass through electric arc furnace The fused magnesia formed by smelting to a molten state and cooled is called seawater magnesia; the magnesia extracted from seawater is called seawater magnesia. Magnesia is one of the important raw materials of refractory materials, which is used to manufacture various magnesia bricks, magnesia-alumina bricks, ramming materials, and charging materials. Those containing more impurities are used for laying steelmaking furnace bottoms, etc.