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Action rules of H_2 and CO in gas-based direct reduction of iron ore pellets

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Journal of Central South University 2012年第8期19卷 2291-2296页

作者：易凌云黄柱成彭虎姜涛 School of Minerals Processing and Bioengineering Central South University Changsha Syno-Therm Co. Ltd.

Alastraet： The gas-based direct reduction of iron ore pellets was carried out by simulating the typical gas composition in coal gasification process, Midrex and HyMII processes. The influences of gas composition and temperature on reduction were studied. Results show that the increasing of HE proportion is helpful to improve the reduction rate. However, when ~o（H2）：~o（CO）〉1.6：1, changes of HE content have little influence on it. Appropriate reduction temperature is about 950 ℃, and higher temperature （1 000 ℃） may unfavorably slow the reduction rate. From the kinetics analysis at 950 ℃, the most part of reduction course is likely controlled by interfacial chemical reaction mechanism and in the final stage controlled by a combined effect of gaseous diffusion and interfacial chemical reaction mechanisms. From the utilizations study of different reducing gases at 950 ℃, the key step in reduction course is the 3rd stage （FeO→Fe）, and the utilization of reducing gas increases with the rise of HE proportion.

关键词： iron ore pellets coal gas gas-based direct reduction reduction kinetics gas utilization

Utilization of waste polyethylene terephthalate as a reducing agent in the reduction of iron ore composite pellets

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International Journal of Minerals,Metallurgy and Materials 2014年第8期21卷 748-754页

作者： Gkhan Polat Burak Birol Muhlis Nezihi Saridede Department of Metallurgical and Materials Engineering Yildiz Technical University Istanbul Turkey

The increasing consumption of plastics inevitably results in increasing amounts of waste plastics. Because of their long degradation periods, these wastes negatively affect the natural environment. Numerous studies have been conducted to recycle and eliminate waste plastics. The potential for recycling waste plastics in the iron and steel industry has been underestimated; the high C and H contents of plastics may make them suitable as alternative reductants in the reduction process of iron ore. This study aims to substitute plastic wastes for coal in reduction melting process and to investigate their performance during reduction at high temperature. We used a common type of waste plastic, polyethylene terephthalate （PET）, because of its high carbon and hydrogen contents. Composite pellets containing PET wastes, coke, and magnetite iron ore were reduced at selected temperatures of 1400 and 1450℃ for reduction time from 2 to 10 min to investigate the reduction melting behavior of these pellets. The results showed that an increased temperature and reduction time increased the reduction ratio of the pellets. The optimum experimental conditions for obtaining metallic iron （iron nuggets） were reduction at 1450℃ for 10 min using composite pellets containing 60% PET and 40% coke.

关键词： polyethylene terephthalate (PET) waste recycling reducing agents iron ore pellets ore reduction

Experimental and numerical investigation of iron ore pellet firing using coupled CFD-DEM method

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PARTICUOLOGY 2024年第10期93卷 75-86页

作者： Amani, Hafez Alamdari, Eskandar Keshavarz Moraveji, Mostafa Keshavarz Peters, Bernhard Amirkabir Univ Technol Sch Mat Engn & Adv Proc 424 Hafez Ave Tehran 158754413 Iran Univ Luxembourg Fac Sci Technol & Med Campus Kirchberg 6Rue Coudenhove Kalergi L-1359 Kirchberg Luxembourg

iron ore pellets are the main feedstock in ironmaking processes. While extensive research has addressed numerical modeling of the iron ore pellet induration process, little effort has been made to describe the intricate thermochemical processes occurring within the reactor starting from the pellet and particularly at the intra-particle scale. In this regard, discrete-continuous methods like CFD-DEM can generate more realistic, irregular particle assemblies, which leads to significantly more accurate predictions of voidage variation, wall effects, temperature distribution, and associated mass transfer phenomena. This study presents a numerical model based on computational fluid dynamics (CFD) coupled with the discrete element method (DEM) to simulate the thermal induration process of iron ore pellets. The presented model solving heat, mass, and momentum conservation equations for both continuous and discrete phases, provides detailed information on the thermochemical aspects of the process. Pilot-scale induration experiment was conducted to validate model predictions in terms of thermal history and final conversion fraction. It was found that inlet charge specifications, such as particle and pellet size, significantly impact the productivity of pelletizing plants, highlighting the potential of the presented model to optimize the process and improve plant productivity. (c) 2024 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

关键词： CFD-DEM Heat and mass transfer iron ore pellets Powder and pellet size Modeling INDURATION PROCESS MATHEMATICAL-MODEL HEAT-TRANSFER FLOW BED MAGNETITE MECHANISMS SIMULATION OXIDATION KILN

Effect of magnesia on the compressive strength of pellets

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International Journal of Minerals,Metallurgy and Materials 2014年第5期21卷 431-437页

作者： Feng-man Shen Qiang-jian Gao Xin Jiang Guo Wei Hai-yan Zheng School of Materials and Metallurgy Northeastern University

The compressive strength of MgO-fluxed pellets was investigated before and after they were reduced. The porosity and pore size of green pellets, product pellets, and reduced pellets were analyzed to clarify how MgO affects the strength of the pellets. Experimental resuits show that when the MgO-bearing flux content in the pellets increases from 0.0wt% to 2.0wt%, the compressive strength of the pellets at ambient temperature decreases, but the compressive strength of the pellets after reduction increases. Therefore, the compressive strength of the pellets after reduction exhibits no certain positive correlation with that before reduction. The porosity and pore size of all the pellets （with different MgO contents） increase when the pellets are reduced. However, the increase in porosity of the MgO-fluxed pellets is relatively smaller than that of the traditional non-MgO-fluxed pellets, and the pore size range of the MgO-fluxed pellets is relatively narrower. The reduction swelling index （RSI） is a key factor for governing the compressive strength of the reduced pellets. An approximately reversed linear relation can be concluded that the lower the RSI, the greater the compressive strength of the reduced pellets is.

关键词： iron ore pellets compressive strength magnesia ore reduction swelling

Effect of carbon species on the reduction and melting behavior of boron-bearing iron concentrate/carbon composite pellets

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International Journal of Minerals,Metallurgy and Materials 2013年第6期20卷 522-528页

作者： Guang Wang Yin-gui Ding Jing-song Wang Xue-feng She Qing-guo Xue State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing

iron nugget and boron-rich slag can be obtained in a short time through high-temperature reduction of boron- bearing iron concentrate by carbonaceous material, both of which are agglomerated together as a carbon composite pellet. This is a novel flow sheet for the comprehensive utilization of boron-bearing iron concentrate to produce a new kind of man-made boron ore. The effect of reducing agent species （i.e., carbon species） on the reduction and melting process of the composite pellet was investigated at a laboratory scale in the present work. The results show that, the reduction rate of the composite pellet increases from bituminite, anthracite, to coke at temperatures ranging from 950 to 1300~C. Reduction temperature has an important effect on the microstructure of reduced pellets. Carbon species also affects the behavior of reduced metallic iron particles. The anthracite-bearing composite pellet melts faster than the bituminite- bearing composite pellet, and the coke-bearing composite pellet cannot melt due to the high fusion point of coke ash. With anthracite as the reducing agent, the recovery rates of iron and boron are 96.5% and 95.7%, respectively. This work can help us get a further understanding of the new process mechanism.

关键词： iron ore pellets iron ore reduction boron bituminite anthracite coke