Formation and characterization of metallic iron grains in coal-based reduction of oolitic iron ore

• Published in: International journal of minerals, metallurgy and materials metallurgy and materials, 2017-02, Vol.24 (2), p.123-129
• Main Authors: Sun, Yong-sheng, Han, Yue-xin, Li, Yan-feng, Li, Yan-jun
• Format: Article
• Language: English
• Subjects: Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Corrosion and Coatings; Glass; Grain growth; Grain size; Growth models; Iron compounds; Iron ores; Materials Science; Metallic Materials; Mineralogy; Natural Materials; Parameters; Particle size; Protuberances; Slag; Surfaces and Interfaces; Thin Films; Tribology; X-ray spectroscopy
• ISSN: 1674-4799; 1869-103X
• DOI: 10.1007/s12613-017-1386-5

To reveal the formation and characteristics of metallic iron grains in coal-based reduction,oolitic iron ore was isothermally reduced in various reduction times at various reduction temperatures. The microstructure and size of the metallic iron phase were investigated by scanning electron microscopy,energy-dispersive X-ray spectroscopy,and a Bgrimm process mineralogy analyzer. In the results,the reduced Fe separates from the ore and forms metallic iron protuberances,and then the subsequent reduced Fe diffuses to the protuberances and grows into metallic iron grains. Most of the metallic iron grains exist in the quasi-spherical shape and inlaid in the slag matrix. The cumulative frequency of metallic iron grain size is markedly influenced by both reduction time and temperature. With increasing reduction temperature and time,the grain size of metallic iron obviously increases. According to the classical grain growth equation,the growth kinetic parameters,i.e.,time exponent,growth activation energy,and pre-exponential constant,are estimated to be 1.3759 ± 0.0374,103.18 k J·mol-1,and 922.05,respectively. Using these calculated parameters,a growth model is established to describe the growth behavior of metallic iron grains.