Effect of Mineral Phase Ratios on Reduction Behavior of Multi-component Calcium Ferrite Extracted from Iron Ore Sinter

• Published in: Tetsu to hagane Vol. 111; no. 12; pp. 737 - 750
• Main Authors: Maruoka, Daisuke, Kimura, Nanase, Kasai, Eiki, Murakami, Taichi
• Format: Journal Article
• Language: Japanese
• Published: The Iron and Steel Institute of Japan 15.08.2025; 一般社団法人 日本鉄鋼協会
• Subjects: in-situ XRD; iron ore sinter; Ironmaking; magnetic separation; reducibility; SFCA-I; SFCA-III
• ISSN: 0021-1575; 1883-2954; 1883-2954
• DOI: 10.2355/tetsutohagane.TETSU-2024-151

In this study, the method to extract multi-component calcium ferrite (CF) into actual iron ore sinter is proposed and its reducibility is investigated under N2–CO–CO2 atmosphere. Actual iron ore sinter are pre-reduced at 500°C for 3 h in N2–CO–CO2–H2–H2O atmosphere and then sample particles containing mainly multi-component CF are successfully obtained through crashing and wet magnetic separation.In the isothermal reduction at 700–800°C, the reduction rate shows positive correlation with compositions of SFCA-I and SFCA-III up to early stage of reduction, and the negative correlation is obtained with SFCA. However the relationship is reversed, for example at 750°C for approximately 90 s. After approximately 380 s, there is no longer any correlation between SFCA and the reduction rate. It indicates that SFCA-I and SFCA-III are already reduced to intermediate products up to 90 s and the reduction of SFCA affects the reduction rate up to 360 s at 750°C.In the heating reduction using in-situ XRD, the formation of wustite is identified along with the decrease in the intensity of multi-component CF from around 600°C. The intensity of SFCA-III decreases from around 550°C and disappears at 760°C, whereas the SFCA-I decreases more gradually. It is known as the multi-component CF consists of series of spinel and pyroxene structure. Since the proportion of S units is SFCA-III > SFCA-I > SFCA, it implies that the reduction of Fe ions advances in S units than in P units.