The furnace age is a restrictive link to improve equipment operation quality and reduce costs. According to the situation of the steelmaking plant itself, finding the most suitable and economical furnace age and rationally using refractory materials in each part of the electric furnace can reduce the consumption of refractory materials to a certain extent and achieve the purpose of saving energy and reducing consumption; at the same time, the increase in furnace age is also To a certain extent, the production time is extended and the labor efficiency is improved. Due to the asynchronous service life of the large furnace bottom brick and the furnace lining brick during use, the life of the electric furnace is low, and sometimes it is extremely difficult to repair due to the serious damage of the large furnace bottom brick. In order to solve this problem, the use of bottom magnesium dry ramming materials has been popularized on electric furnaces.
1 Performance of dry ramming material
The ramming material used is a high-iron, high-calcium magnesia bulk material, which is characterized in that it can replace the large bricks at the bottom of the furnace and be directly laid on the permanent layer of the bottom of the furnace. After the construction is completed, the first furnace can be directly carried out without baking. smelting. The material starts to sinter at about 1100°C, and can be completely sintered when the temperature reaches above 1600°C, forming a solid dense body with good high-temperature strength. Its physical and chemical indicators are as follows: W (MgO) = 80%, W (CaO) = 7%-9%, bulk density (g cm-3) is 2.21 (1300°C 3h), 2.60 (1600°C 3h), obvious pores Rate is 38% (1300°C 3h), 29% (1600°C 3h), compressive strength (MPa) is 2.2 (1300°C 3h), 30.6 (1600°C 3h), flexural strength (MPa) is 1.2 (1300°C 3h), 13.5 (1600°C 3h), the maximum operating temperature is 1800°C.
2 Technical characteristics of dry ramming material
The dry ramming material is made of MgO-CaO-Fe2O3 series high-grade synthetic sand as the main raw material. The main function of Fe2O3 is to promote the sintering of the ramming material. It can react with CaO to form dicalcium ferrite with low melting point (C2F, melting point 1449°C) and tetracalcium aluminoferrite (C4AF, melting point 1415°C).
In the process of steelmaking, since the melting temperature of C2F decreases with the decrease of oxygen partial pressure, the liquid phase temperature of C2F and C4AF is about 1100℃ in the presence of molten iron. Since magnesia ramming materials usually contain a small amount of SiO2 and Al2O3, the temperature at which the liquid phase appears is usually lower than 1100 ° C, that is to say, magnesia dry ramming materials have begun to sinter when they are lower than 1100 ° C. After its rapid sintering, it forms a strong, high-temperature-strength sintered layer to resist the mechanical impact of adding scrap. The main components of magnesium dry ramming material are MgO and CaO, which have excellent resistance to slag penetration and erosion. When the ramming material meets the iron-rich slag, the MgO in the material reacts with Fe2O3 to form magnesium richite and magnesium ferrite with a high melting point, which protects the material; when the dry ramming material meets the high-SiO2 slag When they meet, the CaO in the material reacts with SiO2 to form a high-melting point dicalcium silicate (C2S) enrichment layer, and the excess components in the slag continue to infiltrate inward, and react with CaO to form a high-melting point tricalcium silicate (C3S) ) enrichment layer. So far, the erosion and penetration of SiO2 have stagnated. The formation of two high-melting-point silicate-enriched layers, C2S and C3S, moderates and retards the infiltration of high-SiO2 slag. The actual use is that the reaction zone has only a thin layer, and after the reaction zone is a transition layer dominated by high-melting point periclase, and then inside is the bulk material, which means that this dry ramming material can maintain a deep layer moderate dispersion.
