Basic refractories are primarily composed of basic oxides such as magnesium oxide and calcium oxide, and offer excellent resistance to alkaline slag attack. The following are some common basic refractories:
Magnesia bricks: These are primarily composed of magnesium oxide, typically exceeding 80%-85%. They have high refractoriness, generally exceeding 2000°C, and offer excellent resistance to alkaline and iron slag. They also possess strong chemical stability and high high-temperature strength. They are primarily used in steelmaking equipment such as open-hearth furnaces, oxygen-blown converters, and electric furnaces, as well as in high-temperature equipment such as non-ferrous metal smelting equipment.
Magnesia-chrome bricks: These are composed of magnesium oxide and chromium oxide, typically containing 30%-40% magnesium oxide and 10%-20% chromium oxide. They offer excellent resistance to thermal shock and slag attack, particularly against slag containing metals such as chromium and nickel. They also possess excellent high-temperature strength and wear resistance. They are commonly used in areas such as the regenerator of glass kilns and the transition zone of cement rotary kilns.
Magnesia-alumina bricks: These are primarily composed of magnesium oxide and aluminum oxide, with a typical magnesium oxide content of 40%-60% and an aluminum oxide content of 20%-40%. They offer excellent thermal shock resistance, a certain degree of resistance to slag erosion, and good structural stability at high temperatures. They are commonly used in linings for industrial furnaces such as heating furnaces and soaking pits.
Dolomite bricks: These are primarily composed of magnesium carbonate. After calcination, they form a refractory material primarily composed of magnesium oxide and calcium oxide. The magnesium oxide content is typically 30%-40% and the calcium oxide content is 40%-50%. They are highly resistant to alkaline slag and exhibit good high-temperature performance and corrosion resistance, but they are susceptible to hydration and require moisture-proofing during storage and use. They can be used in areas such as the bottom and walls of alkaline open-hearth and electric furnaces.
Magnesia-spinel bricks: These are primarily composed of magnesium oxide and spinel, with a magnesium oxide content of 70%-90% and a spinel content of 10%-30%. It has excellent thermal shock resistance, slag erosion resistance, and high-temperature mechanical properties, a low thermal expansion coefficient, and good volume stability at high temperatures. It is commonly used in thermal equipment such as converters, electric furnaces, and ladles in the steel industry, as well as rotary kilns in the cement industry.
