Magnesia alumina brick is an alkaline refractory material made of magnesia and industrial lead oxide or alumina, crushed, shaped, and fired at about 1600°C. The refractoriness of magnesia-aluminum bricks is greater than 2000℃, and its resistance to rapid cooling and heating is better than that of magnesia bricks, and it can withstand the erosion of alkaline slag. It is used to build the furnace roof of steelmaking alkaline open hearth furnace and electric furnace.