Effect of Slag Basicity on Dephosphorization at Lower Basicity and Lower Temperature Based on Industrial Experiments and Ion-Molecular Coexistence Theory
Abstract
In the present work, the effect of dephosphorization slag basicity on the dephosphorization of hot metal has been studied in the lower temperature range of 1370 °C to 1420 °C and the lower basicity of 1.26 to 2.20 with new double slag converter steelmaking process (NDSP). Based on the ion-molecule coexistence theory (IMCT), the thermodynamic model IMCT-Ni of dephosphorization slag is established. With increasing basicity from 1.26 to 2.20, the phosphorus distribution ratio LP between hot metal and slag increases. The dephosphorization ratio and the decarbonization ratio both increase, while the demanganization ratio decreases. The morphologies of P-rich phase change from long strip shape (B = 1.26-1.37) to dendritic shape (B = 1.50) and to massive shape (B = 1.71-2.20). The area of P-rich phase increases from about 4 μm2 to about 8000 μm2. The content of P2O5 in the P-rich phase increases and the value of the coefficient n in nC2S-C3P of the P-rich phase decreases from 6-20 to 1-2. The phosphorus-enrichment contribution ratio of calcium silicate is in the order of RC2S>RCS>RC3S>RC3S2. The phosphorus-enrichment degree in dephosphorization slag is enhanced mainly by C2S-C3P. With increasing basicity, the calculated results of IMCT-(pct C2S-CjP) and RC2S are well consistent with the measurement results of AP-rich phase and (pct P2O5)P-rich phase of industrial experiment, indicating that the IMCT calculated results can correctly express the phosphorus-enrichment degree of dephosphorization slag.
- Publication:
-
Metallurgical and Materials Transactions B
- Pub Date:
- October 2021
- DOI:
- 10.1007/s11663-021-02270-y
- Bibcode:
- 2021MMTB...52.3403S