检索结果-南通市图书馆

direct reduction of carburized pre-reduced pellets by microwave heating

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2014年第1期21卷 351-357页

作者：胡兵黄柱成易凌云姜涛 School of Minerals Processing and Bioengineering Central South University Zhongye Changtian International Engineering Co. Ltd.

A new iron-making process using carburized pre-reduced iron ore pellets and microwave heating is investigated. The pre-reduced pellets, with a porous structure, and fine particles are carburized homogeneously at 400-650 ℃ in a CO atmosphere. The carburized carbon not only acts reaction as a reduction agent, but also absorbs microwave in the reduction process. Hence, the carburized pre-reduced pellets can be rapidly reduced by microwave heating. There are three procedures involved in the process, namely, gas-based pre-reduction, low-temperatttre carburization and deep reduction by microwave heating. Carburized pre-reduced iron ore pellets show a rapid temperature rise that is twice as fast as the results for pre-reduced pellets in the laboratory. This not only improves the efficiency of the microwave heating, but also accelerates the reduction of iron oxides. The temperature of the pre-reduced pellets rises to 1050 ℃ in 45 min when the carburization rate is 2.02%, and the metallization rate and compressive strength reach 94.24% and 1725 N/pellet, respectively.

关键词： oxidized pellets pre-reduction carburizing microwave heating direct reduction

Staged reaction kinetics and characteristics of iron oxide direct reduction by carbon

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2015年第10期22卷 1025-1032页

作者： Ru-fei Wei Da-qiang Cang Ling-ling Zhang Yuan-yuan Bai School of Metallurgical and Ecological Engineering University of Science and Technology Beijing State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing School of Civil and Environmental Engineering University of Science and Technology Beijing Key Laboratory of Electromagnetic Processing of Materials of the Ministry of Education Northeastern University

Staged reduction kinetics and characteristics of iron oxide direct reduction by carbon were studied in this work. The characteristics were investigated by simultaneous thermogravimetric analysis, X-ray diffraction（XRD）, and quadrupole mass spectrometry. The kinetics parameters of the reduction stages were obtained by isoconversional（model-free） methods. Three stages in the reduction are Fe2O3→Fe3O4, Fe3O4→Fe O, and Fe O→Fe, which start at 912 K, 1255 K, and 1397 K, respectively. The CO content in the evolved gas is lower than the CO2content in the Fe2O3→Fe3O4stage but is substantially greater than the CO2 contents in the Fe3O4→Fe O and Fe O→Fe stages, where gasification starts at approximately 1205 K. The activation energy（E） of the three stages are 126–309 k J/mol, 628 k J/mol, and 648 k J/mol, respectively. The restrictive step of the total reduction is Fe O→Fe. If the rate of the total reduction is to be improved, the rate of the Fe O→Fe reduction should be improved first. The activation energy of the first stage is much lower than those of the latter two stages because of carbon gasification. Carbon gasification and FexOy reduction by CO, which are the restrictive step in the last two stages, require further study.

关键词： iron oxides direct reduction reduction kinetics re

Particle agglomeration behavior in fluidized bed during direct reduction of iron oxide by CO/H_(2)mixtures

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2023年第4期30卷 626-634页

作者： Feng Lu Hong Zhong Bo Liu Jian Xu Sheng-fu Zhang Liang-ying Wen School of Materials Science and Engineering Chongqing UniversityChongqing 400044China Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and Advanced Materials Chongqing UniversityChongqing 400044China School of Mechanical and Materials Engineering Washington State UniversityPullmanWA 99163USA

The agglomeration behavior of particles significantly impacts on the defluidization occurring in a fluidized bed during the direct reduction *** influence of CO/H_(2)ratio on surface diffusion of iron atoms was proposed,and the solid bridge force between iron oxide particles was quantificationally ***,the solid bridge force was successfully added into a CFD–DEM(computational fluid dynamics–discrete element method)model combined with heat transfer and mass transport to investigate the detailed information of agglomeration in a fluidized bed,including the spatial distribution of temperature,velocity and metallization of iron oxide *** region of defluidization is sensitive to the reduction *** the same reduction temperature,the iron oxide powder will perform higher metallization and stable fluidization properties with molar fraction of H_(2)in the range of 0.6–0.8,when iron oxide is reduced by CO/H_(2)mixture.

关键词： direct reduction Computational fluid dynamics Discrete element method Particle agglomeration CO/H_(2)mixture Micro morphology

Kinetics and mechanism of coal-based direct reduction of highchromium vanadium-titanium magnetite

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2022年第11期29卷 1723-1733页

作者： Jian Yang Tao Jiang Shi-hong Ma Song-tao Yang Mi Zhou School of Information Science and Engineering Northeastern UniversityShenyang 110819LiaoningChina School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina School of Materials and Metallurgy University of Science and Technology LiaoningAnshan 114051LiaoningChina

High-chromium vanadium-titanium magnetite(HCVTM)is a valuable resource containing metal elements such as iron,vanadium,titanium,and *** recycle these elements,direct reduction is an efficient *** mechanism and reaction kinetic parameters for the direct reduction of HCVTM were *** results show that the reduction degree increases obviously when the C/O ratio and temperature *** analysis showed a dramatic mass loss in the direct reduction of HCVTM in the temperature range of 985-1160℃.From 1200 to 1350℃,the reduction curves for the isothermal reduction of HCVTM followed the same trend,with a sharp increase in the initial reaction zone and a slight increase in the reduction rate with increasing time,and finally,the isothermal reduction process of HCVTM was divided into several limiting stages with varying degrees,with inconsistent limiting factors for the reaction rate at different *** results also show that the activation energy decreases slightly at larger degrees of ***,the apparent rate constant k(T)increased with increasing reduction temperature,with lnk(T)showing a good linear relationship with temperature.

关键词： High-chromium vanadium-titanium magnetite direct reduction reduction rate Kinetic Thermodynamic Analysis

Factor analysis on the purity of magnesium titanate directly prepared from seashore titanomagnetite concentrate through direct reduction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2020年第11期27卷 1462-1470页

作者： Xiao-ping Wang Zhao-chun Li Ti-chang Sun Jue Kou Xiao-hui Li School of Mining and Coal Inner Mongolia University of Science and TechnologyBaotou 014010China China Sinda Intellectual Property Limited Beijing 100033China School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China

Magnesium titanate was prepared directly through external coal reduction of seashore titanomagnetite concentrate and magnesium oxide(MgO).The effects of roasting temperature and the type and dosage of reductants on the purity of generated magnesium titanate particles were systematically *** electron microscopy and energy-dispersive spectroscopy analyses were performed to characterize the magnesium titanate particles and observe their purity under different *** showed that the roasting temperature remarkably influenced the purity of magnesium *** 1200,1300,and 1400℃,some magnesium ferrite and magnesium aluminate spinel were dissolved in magnesium ***,as the roasting temperature increased to 1500℃,relatively pure magnesium titanate particles were generated because no magnesium ferrite was dissolved in *** type and dosage of the reductants also remarkably affected the purity of magnesium *** amount of fine metallic iron disseminated in the magnesium titanate particles obviously decreased when lignite was used as a reductant at a dosage of 70wt%.Thus,high-purity magnesium titanate particles *** a roasting temperature of 1500℃and with 70wt%lignite,the magnesium titanate product with a yield of 30.63%and an iron content of 3.01wt%was obtained through magnetic separation.

关键词： seashore titanomagnetite magnesium oxide direct reduction magnesium titanate

Influence of Na_2CO_3 as Additive on direct reduction of Boron-bearing Magnetite Concentrate

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2016年第2期23卷 103-108页

作者： Yong-li LI Jing-kui QU Guang-ye WEI Tao QI National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology Institute of Process EngineeringChinese Academy of Sciences Key Laboratory of Green Process and Engineering Institute of Process EngineeringChinese Academy of Sciences

Boron-bearing magnetite concentrate is typically characterized by low grade of iron and boron （wTFe = 51%- 54%, WB2O3 =6%-8%）, as well as the close intergrowth of ascharite phase and magnetite phase. A promising technology was proposed to separate iron and boron by coupling the direct reduction of iron oxides and Na activation of boron minerals together. The influence of Na2CO3 as additive on the direct reduction of boron-bearing magnetite was studied by chemical analysis, kinetic analysis, XRD analysis and SEM analysis. The results showed that the ad- dition of Na2CO3 not only activated boron minerals, but also reduced the activation energy of the reaction and pro- moted the reduction of iron oxides. Besides, the addition of Na2CO3 changed the composition and melting point of non-ferrous phase, and then promoted the growth and aggregation of iron grains, which was conducive to the subse- quent magnetic separation. Thus, the coupling of the two processes is advantageous,

关键词： ludwigite kinetic analysis direct reduction magnetic separation sodium carbonate

Recovery of iron from copper tailings via low-temperature direct reduction and magnetic separation: process optimization and mineralogical study

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2017年第9期24卷 974-982页

作者： Rui-min Jiao Peng Xing Cheng-yan Wang Bao-zhong Ma Yong-Qiang Chen School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China

Currently, the majority of copper tailings are not effectively developed. Worldwide, large amounts of copper tailings generated from copper production are continuously dumped, posing a potential environmental threat. Herein, the recovery of iron from copper tailings via low-temperature direct reduction and magnetic separation was conducted; process optimization was carried out, and the corresponding mineralogy was investigated. The reduction time, reduction temperature, reducing agent (coal), calcium chloride additive, grinding time, and magnetic field intensity were examined for process optimization. Mineralogical analyses of the sample, reduced pellets, and magnetic concentrate under various conditions were performed by X-ray diffraction, optical microscopy, and scanning electron microscopy-energy-dispersive X-ray spectrometry to elucidate the iron reduction and growth mechanisms. The results indicated that the optimum parameters of iron recovery include a reduction temperature of 1150A degrees C, a reduction time of 120 min, a coal dosage of 25%, a calcium chloride dosage of 2.5%, a magnetic field intensity of 100 mT, and a grinding time of 1 min. Under these conditions, the iron grade in the magnetic concentrate was greater than 90%, with an iron recovery ratio greater than 95%.

关键词： copper tailings iron direct reduction magnetic separation recovery process optimization

Upgrade of nickel and iron from low-grade nickel laterite by improving direct reduction-magnetic separation process

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2022年第8期29卷 1164-1175页

作者： Hong-yu Tian Zheng-qi Guo Ruo-ning Zhan Jian Pan De-qing Zhu Cong-cong Yang Liao-ting Pan Xue-zhong Huang School of Minerals Processing and Bioengineering Central South UniversityChangsha 410083HunanChina Beibu Gulf New Materials Co. Ltd.Beihai 536000GuangxiChina

Low-grade saprolite nickel laterite,characterized by complicated minerals composition and fine-grained and complex dissemination,was commonly treated with a low recovery efficiency of Ni and Fe by conventional ***,an improved direct reduction and magnetic separation process was ***,the mechanisms on the enhanced growth of the Ni-Fe particles and the phase transformation in the nickel laterite pellets were *** low-nickel concentrates as a nucleating agent can obviously decrease the activation energy for growth of Ni-Fe alloy particles during the improved direct reduction process from 197.10 to 154.81 kJ/mol when the low-nickel concentrates were added from 0 to 20%.Hence,it is able to decrease nucleation barrier,induce the growth of Fe-Ni alloy particles and increase their average *** a result,the size of Ni-Fe particles in the pellets from less than 10 lm grew to more than 20 lm,which is beneficial for the full liberation and recovery of Ni and Fe in subsequent magnetic separation ***,the preferable Ni-Fe alloy concentrates with 6.44%Ni and 82.48%Fe can be prepared with corresponding recovery rates of 96.90%and 95.92%,respectively,when adding 20%low-nickel concentrates.

关键词： Nickel laterite Low-nickel concentrate Nucleating agent Growth kinetics Ni-Fe alloy direct reduction Magnetic separation

A high-efficiency separation process of Fe and Zn from zinc-bearing dust by direct reduction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2022年第10期29卷 1559-1572页

作者： Ding-zheng Wang De-qing Zhu Jian Pan Zheng-qi Guo Hong-yu Tian Yu-xiao Xue School of Minerals Processing and Bioengineering Central South UniversityChangsha410083HunanChina

It is urgent to dispose of zinc-bearing dust from steel plants,and direct reduction process is an effective method to remove hazardous metals and recycle iron from the *** reduction behavior of carbon-containing pellets which were made from three kinds of zinc-bearing dust was *** the pellets were reduced at 1200℃ for 50 min,the reduced pellets with cold compressive strength of 1164 N pellet−1 and Zn contentdirectly used as burden for improving the blast furnace operation without further *** results of isothermal kinetic study showed that the iron oxide reduction rate was controlled by the chemical *** strengthening mechanism of reduced pellets and iron oxide reduction mechanism was investigated by thermodynamic calculation besides X-ray diffraction,scanning electron microscopy combined with energy dispersive spectrometry,and optical microscopy *** was found that higher temperatures are required for the reduction of spinel phase(zinc ferrite)and olivine phase(hedenbergite).The generation and growth of metallic iron bridges could significantly increase the compressive strength of reduced *** iron oxide reduction in the carbon-containing pellets followed the uniform internal reduction model and possessed a high apparent reaction rate,which can improve energy utilization rate and production efficiency.

关键词： Zinc-bearing dust reduction mechanism Kinetics High efficiency direct reduction