The whole process of ladle capping technology is adopted in some large domestic steelmaking enterprises such as Handan Iron and Steel, Tangshan Iron and Steel, Maanshan Iron and Steel, Xingshan Iron and Steel, Lianyuan Iron and Steel, etc. Tangshan Iron and Steel No. 2 Rolling Plant adopted technical measures such as ladle capping throughout the process, increasing ladle turnover rate, and low-temperature and high-speed casting. °C, 11.1 °C and 25.9 °C. Through the whole process of ladle capping, Xingshan Iron and Steel has lowered the tapping temperature of the converter by an average of 10 to 30 °C, which has increased the qualification rate of the middle ladle temperature of the continuous caster by 8%. Compared with the ladle baking for 8 hours after the ladle is covered, the ladle lining temperature is increased by 8 °C, which creates conditions for converter production and energy saving and consumption reduction.
However, for a long time, domestic design units and ladle cover manufacturers have been accustomed to adopt heavy castable structure, castable fiber blanket composite structure for thermal insulation, and fiber blanket structure. These methods solve the problem of molten steel temperature drop to a certain extent, but it is difficult to fundamentally solve the problem of light-weight and long-life ladle cover, which has brought obstacles to the promotion and innovation of ladle cover throughout the process. The main reasons are as follows:
1) The density of the heavy clad castable is heavier (2.8g/cm³). When it is lifted and unloaded at high temperature, the working face is subjected to tensile force and the back is affected. The metal frame has low mechanical properties at high temperature, and the heavy castable can withstand the tensile force. The capacity is low. When the cover is lifted and unloaded at high temperature, the outer cover is deformed, which makes the upper cover of the cover bulge, thus affecting the service life of the cover. In addition, the thermal shock resistance of heavy castables is poor, and the thermal conductivity is large. During the use process, the heat loss of the molten steel radiation and conduction is large, and the energy saving effect of the ladle covering the whole process is not very ideal, which limits the ladle. Capped development.
2) The energy-saving effect of the use of fiber folded blocks on the whole ladle cover is shown, and the density of fiber folded blocks is small, but under the high temperature state of molten steel radiation, the refractory fiber grain boundaries are continuously affected during the grain growth period. Similar atoms (particles) are filled and solid solution occurs, and the impurity enrichment at the sample boundary becomes more and more. However, the arrangement of impurities is irregular, the binding force is small, and the sensitivity to temperature changes is strong. Therefore, the strength at the grain boundaries is much weaker than the bond between the lattices, causing stress to penetrate the grain boundaries at the shrinking diameter, and the fiber rods are broken (ie, pulverized). Large pieces of fiber folded blocks fell off, and the high temperature radiated by the molten steel burned through the fallen fiber folded blocks to burn out the covered iron sheet, which also restricted the development of ladle covering throughout the process.
In view of the above domestic reality, combined with the development of functionalization of lightweight and high-strength castable products, the ladle cover lining was changed to a lightweight and high-strength castable structure, and the application practice was carried out in Sangang, and satisfactory results were obtained (greater than 550 The service life of the general ladle is 200-300 heats. Longevity and energy saving are the requirements for the use of refractory materials. Lightweight and high-strength castables have pushed the domestic ladle insulation work to a new level.
