Baosteel once put forward the concept of “continuous treatment of molten iron”, which continuously carries out “three desulphurization”, desulfurization, dephosphorization and desiliconization in the tap ditch, thus making the molten iron pretreatment process more efficient, simple and energy-saving. However, the materials used in the “triple removal” and the slag formed after the reaction have a strong erosive effect on the refractory material, causing the material to be damaged too quickly and seriously affecting the service life of the material. Therefore, it is particularly important to improve the corrosion resistance of Al₂O₃-SiC materials used in the casting system.
Compared with cement-bonded castables, silica sol-bonded castables have better physical properties and high-temperature properties, especially good volume stability, anti-cracking and spalling resistance, and can be constructed at relatively high temperatures. Quickly bake and put into use, shorten the construction period and improve the production efficiency. This is mainly because there are pores in the silica sol binder, which improves the air permeability of the material, so it can be applied at a higher temperature and dried quickly. Compared with the cement-bonded Al₂O₃-SiC castable, its curing, drying and baking time can be shortened by more than half.
The use of silica sol in Al₂O₃-SiC castables can significantly improve the slag corrosion resistance of refractories. The use of silica sol instead of pure calcium aluminate cement as a binder can enhance the flexural strength and compressive strength of Al₂O₃-SiC castables after heat treatment, and the addition of silica sol is beneficial to reduce the formation temperature of SiAION phase and form a good performance. β-SiAION phase, thereby increasing the strength of the castable.
From the perspective of the use effect of castables, Al₂O₃-SiC castables combined with silica sol have been used in high-temperature furnaces in the field of ironmaking such as blast furnace tap ditch, torpedo pot, iron mixing furnace, and molten iron ladle. Durability is better than non-sol-bonded similar castables. In 2014, silica sol combined with Al₂O₃-SiC-C castables was applied in the tapping trench of a 5250m³ blast furnace in a steel plant, and the iron throughput exceeded 250,000 t at a time, which is more than the original use of non-silica sol combined with Al₂O₃-SiC-C castables. Compared with the 200,000 t flux, the iron volume has increased by 25%.
