The converter plays the functions of decarbonization, dephosphorization, desulfurization, alloying, heating, removal of inclusions and so on in steelmaking. The converter does not need additional heat during smelting, and relies on the oxidation reaction in molten steel to release heat. In the converter, the lining, steel outlet and breathable brick are all composed of refractory materials. Since the development of magnesia carbon brick in the 1970s, because of its comprehensive performance is obviously better than dolomite carbon brick, so it has been widely used. Magnesia carbon brick is composed of magnesia aggregate, graphite, antioxidant, binder, etc. It has the advantages of high corrosion resistance, anti-spalling, anti-slag, anti-thermal shock and so on. By changing the particle size composition of magnesia aggregate and graphite, or changing the amount of antioxidants added, the strength, erosion resistance and oxidation resistance of magnesia carbon brick can be significantly changed. In actual production, the composition of magnesia carbon brick can be fine-tuned according to the melting characteristics of each part of the converter, which can increase the life of the converter and reduce the comprehensive cost.

With the implementation of China's "double carbon" policy, the carbon consumption of refractory materials cannot be ignored. Under the new smelting technology of converter, the application of refractory materials used in various parts of converter also faces new challenges. Traditional magnesium-carbon refractories have high carbon content and high thermal conductivity, which will increase energy consumption and refractory erosion. Especially in the smelting of low carbon steel and ultra-low carbon steel, it will carburize the molten steel and reduce the quality of steel products. Therefore, magnesium carbon refractory low carbonization and related technology innovation will become a new direction of development.

In the smelting cycle of the converter, the following two kinds of melting losses mainly occur in the converter lining. First, the impurity components SiO2 and CaO in magnesia react with magnesia to produce low-melting point substances. Second, FeO in the converter slag reacts with MgO in the refractory to form MGO-FeO solid solution, which reduces the melting point. These two melting phenomena occur simultaneously, resulting in melting loss of magnesia-carbon brick. The dissolution of magnesia has a great influence on the melting loss of magnesia carbon bricks. Therefore, applying high purity raw materials and less magnesia raw materials with grain boundaries to magnesia carbon bricks in serious melting loss areas, and appropriately increasing the content of MgO in slag can improve the melting loss of magnesia carbon bricks.

The oxidation of magnesium-carbon bricks is inevitable during smelting, and the carbon in magnesium-carbon bricks (graphite and carbonaceous binder) is oxidized by oxides in oxidizing gases and slag. The oxidation of magnesia-carbon brick is divided into direct oxidation of carbon and oxygen and indirect oxidation of carbon and oxide. The oxidation of steel outlet, furnace mouth, furnace cap and slag line is obvious, in which the steel outlet and slag line are mainly oxidized by slag, and the furnace mouth and furnace cap are mainly oxidized by gas. After oxidation, the structure of magnesia-carbon brick decreases in loose strength and is gradually eroded under the erosion of air flow and molten steel.

The main damage causes are the bottom of converter, gas supply element and steel outlet. For example, when the converter is drawing steel, the outlet is subject to intermittent thermal shock shock and the wash of molten steel and part of steel slag, resulting in the wear of refractory aggregate. This part is characterized by the coexistence of steel slag and molten steel flow, it is difficult to form a stable slag adhesion layer, graphite and magnesia due to the flow of molten steel washed off. Based on the above problems, the high temperature creep resistance of MG-carbon brick can be improved by adjusting the particle gradation of raw materials to increase the bulk density and adding metal fiber.