Kinetic Study on Thermal Decomposition Behavior of Hematite Ore Fines at High Temperature
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alternatives to ironmaking, novel processes, such as FINEX, HIsarna, and Suspension ironmaking,[1–9] have been attracting greater attention. The main reason is that these novel ironmaking technologies can use iron ore fines directly instead of pellet and sinter. In addition, coke consumption can be significantly reduced or completely eliminated. In the FINEX process, the iron ore fines are preheated and pre-reduced in fluidized bed reactors. However, in order to avoid agglomeration of particles, the reduction temperature in the fluidized bed
LIYONG XING and CHUNSONG WANG are with the Key Laboratory of Ecological Utilization of Multi-Metallic Mineral of Education Ministry, Northeastern University, Shenyang 110819, Liaoning, China, and with the School of Metallurgy, Northeastern University, Shenyang 110819, Liaoning, China. YINGXIA QU, LEI SHAO, and ZONGSHU ZOU are with the Key Laboratory of Ecological Utilization of Multi-Metallic Mineral of Education Ministry, Northeastern University, and with the State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, Liaoning, China, and also with the School of Metallurgy, Northeastern University. Contact email: [email protected] WENJUN SONG is with the Heavy Section Plant of Angang Steel Company Limited, Anshan 114000, Liaoning, China. Manuscript submitted July 12, 2019.
METALLURGICAL AND MATERIALS TRANSACTIONS B
reactors is usually below 1173 K.[10] In the cyclone melting reactor of HIsarna and the flash shaft reactor of Suspension ironmaking technology, the iron ore fines are directly in contact with high-temperature reducing gas during the in-flight process and then fall into the molten bath to complete the final reduction. Therefore, there is no need to worry about the agglomeration problem of iron ore fines. The temperature of reducing gas ranges between 1473 K and 1873 K, which is much higher than that in a fluidized bed reactor. The iron ore fines experience a series of rapid physical and chemical changes, including heating, gaseous reduction, and thermal decomposition at high temperature, during the in-flight process. Both reactions are extremely fast, taking place in a few seconds. It is difficult to distinguish between the thermal decomposition and the gaseous reductions. From a thermodynamic point of view, the essence of both reactions of thermal decomposition and gaseous reduction is the same, which is the process of oxygen removal from iron oxides. However, from a kinetic point of view, the reaction rates and the factors that influence the reaction rates are different. As to the investigation on thermal decomposition of iron ores, many previous studies have been conducted with iron ores, such as goethite, siderite, and limonite, at low temperature,[11–13] since these iron ores can produce high-grade magnetite by using magnetizing roasting-magnetic separation technology. Hematite is a
common ironmaking raw material used in traditional ironmaking processes. Due to the fact that the thermal decomposition of hematite requires a much higher temperat
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