Phosphorus Migration Behavior of Medium-Phosphorus Magnetite Ore during Carbothermic Reduction

• Published in: ISIJ International Vol. 60; no. 3; pp. 442 - 450
• Main Authors: Zhang, Jing, Luo, Guoping, Chen, Yanbiao, Xin, Wenbin, Zhu, Jianguo
• Format: Journal Article
• Language: English
• Published: The Iron and Steel Institute of Japan 15.03.2020
• Subjects: carbothermic reduction; crystal structure; mineral evolution; phosphorus migration
• ISSN: 0915-1559; 1347-5460
• DOI: 10.2355/isijinternational.ISIJINT-2019-214

Time-dependent phosphorus migration characteristics during the carbothermic reduction process have been investigated based on the iron and phosphorus status in medium-phosphorus magnetite ore. The results show that the iron metallization enhanced from 84.38% to 96.49% with the reduction time varying from 10 min to 60 min. However, gasificating dephosphorization first increased from 21.03% to 33.07% and then decreased to 31.61% as a result of the large absorption of reduced phosphorus gas into metallic iron. Optimal phosphorous gasification was achieved at a reduction time of 50 min. Moreover, SEM-EDS and EPMA analyses indicated that the ratio of phosphorus content distributed between the iron phase and gangue minerals evidently increased from 0.12 to 1.01 and 1.18, as the reduction continued from 10 min to 30 min and 50 min. Meanwhile, the phosphorus content in the iron phase increased along with an increase in the carbon and Fe3C contents. Furthermore, the aggravated phosphorus migration into the iron phase is inherently attributed to the smaller lattice discrepancy between FexP and Fe3C in contrast with that between FexP and γ-Fe, which accelerated the entrance of phosphorus into the lattice of Fe3C and the formation of FexP.