Abstract：There are certain advantages in the dephosphorization of limestone powder slag by converter injection. Based on TG-DSC and basic experiments, the mechanism of rapid high-temperature calcination of small particle limestone and dephosphorization of slag was studied. The results show that small particle limestone begins to decompose at around 610 ℃, and the reaction ends at around 860 ℃. The higher the temperature, the more favorable it is for its decomposition. If converter adopts the method of injecting limestone powder for slag making and dephosphorization, the rapid temperature drop effect can be alleviated by batch injection. Local temperature drop is beneficial for the dephosphorization reaction, and it is necessary to find a temperature equilibrium point on slag melting and dephosphorization. As the particle size decreases, the decomposition rate of small limestone particles actually slows down. Limestone particles with average particle size of 0.440 mm and 0.840 mm exhibit porous active lime microstructure after rapid high-temperature calcination for 60 s. With the extension of calcination time, the conversion rate of limestone increases, but the activity after calcination shows a trend of first increasing and then decreasing. The activity of limestone particles with average particle size of 0.440 mm and 0.840 mm can reach more than 350 mL after calcined for 60 s. The dephosphorization experiment of molten iron was carried out by small particle limestone to prepare a dephosphorization agent, endpoint steel P mass fraction decreased to below 0.02%, and the dephosphorization rate was above 83%. Compared to lime slagging and dephosphorization, the speed of small particle limestone slagging and dephosphorization is faster. On the premise of ensuring the slagging effect, the heat consumption of limestone decomposition can reduce the local melting pool temperature, which is conducive to the dephosphorization reaction. The research results can lay a theoretical foundation for the development and application of small particle limestone slagging and dephosphorization technology
2023, Vol. 33 
