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Preparation of calcium ferrite by flue gas desulfurization gypsum

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Journal of Iron and Steel Research(International) 2021年第11期28卷 1357-1365页

作者： Lin-cheng Liu Hai-bin Zuo Wen-guo Liu Zhi-qiang Xu State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

At present,the continuous accumulation of the flue gas desulfurization(FGD)gypsum in steel plants leads to the serious environmental issues and resource waste.To achieve green and sustainable development for the steel industry,it is significant to improve the usage of by-product gypsum.Employing the sintering FGD gypsum,ferric oxide,and graphite carbon as raw materials,the effects of the carbon content,reaction time,and molar ratio of CaO to Fe_(2)O_(3)on the desulfurization rate of gypsum were studied based on the orthogonal experiment.The results show that the order of the three influencing factors on the desulfurization rate of FGD gypsum is:molar ratio of CaO to Fe_(2)O_(3)>reaction time>carbon content.Under the optimal conditions of 20 wt.%carbon content,4 h reaction time,and 1:1 molar ratio of CaO to Fe_(2)O_(3),the desulfurization rate of desulfurization gypsum is 95.79%,and 97.57 wt.%of calcium ferrite appears in the solid product,which can be used as sintering additive to increase the economic benefits of enterprises and realize the green ecological development mode of internal generation and internal digestion of solid waste in iron and steel enterprises.

关键词： Flue gas desulfurization gypsum Desulfurization rate calcium ferrite Sintered ore Green production

Formation Characteristics of calcium ferrite in Low Silicon Sinter

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Journal of Iron and Steel Research(International) 2011年第10期18卷 1-7页

作者： WANG Yi-ci ZHANG Jian-liang ZHANG Fang LUO Guo-ping College of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China College of Material and Metallurgy University of Science and Technology Inner Mongolia Baotou 014010 Inner Mongolia China

Influence of sintering temperature, basicity and MgO content on the formation characteristics of calcium ferrite in low silicon sinter of Baotou Iron and Steel Company was studied by means of mini-sintering test and mineralographic microscope analysis. In addition, the suitable sintering parameters such as temperature and basicity were explored. The results found that optimum temperature for the formation of calcium ferrite is 1 280℃, the basicity of 2.5-2.8 is helpful to the development of acicular or columnar calcium ferrite, and MgO content in the low silicon sintering raw materials should be lower than 2.8 % because MgO can intensively inhibit the formation of calcium ferrite. And calcium ferrite in the sinter belongs to calcium ferrite with low calcium, which is different from that in ordinary sinter at home and abroad. So, it provided theoretical basis for promoting formation of calcium ferrite in low silicon sinter and improving properties of sinter.

关键词： low silicon sinter formation characteristics calcium ferrite sintering temperature basicity

Production of phenolic compounds in catalytic pyrolysis of bagasse lignin in the presence of Ca_(0.5)Pr_(0.5)FeO_(3)

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Journal of Rare Earths 2022年第2期40卷 279-288,I0004页

作者： Hongjing Han Qin Ge Mei Zhang Yanguang Chen Haiying Wang Yanan Zhang Yizhen Wang Hua Song Chunlei Zhang College of Chemistry&Chemical Engineering Northeast Petroleum UniversityDaqing 163318China Heilongjiang Provincial Key Laboratory of Oil&Cos Chemical Technology Daqing 163318China

Herein,sodium dodecylbenzene sulfonate(SDBS)was used as a template to control the synthesis of Ca_(0.5)Pr_(0.5)FeO_(3).Its microstructure,composition,and morphology were detected via X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),and scanning electron microscopy(SEM).The properties of catalyzing bagasse lignin(BL)pyrolysis were determined by thermogravimetric analysis(TG)test and evaluation of a fixed bed alumina microreactor.The results show that the sample Ca_(0.5)Pr_(0.5)FeO_(3)regulated by SDBS has a cubic crystal phase,and the addition of SDBS does not cause phase transition.Moreover,when the SDBS concentration is 0.10 mol/L,the particle size is 200-500 nm and the specific surface area is 11.26 m^(2)/g.The yields of gas,liquid,and solid products in the BL catalytic pyrolysis are 39.58 wt%,26.76 wt%and 32.36 wt%,respectively.The contents of CO_(2)and CO decrease from 54.07%and 4.98%to 45.29%and 3.23%,respectively.The liquid products are mainly guaiacol,syringol,and phenol,and the total selectivity of phenols is 83.67%,accompanied by a small amount of non-aromatic oxygen-containing compounds(five-membered ring(furan)or ester).Compared with the BL pyrolysis and Ca_(0.5)Pr_(0.5)FeO_(3)catalytic pyrolysis products,the selectivity of guaiacol compounds increases by43.26%,while those of syringol compounds and phenylketones decrease by 30.08%and 3.39%,respectively.The selectivity of 2,6-dimethoxyphenol is 28.37%.After five catalytic pyrolysis-regeneration cycles,the characteristic peaks of the catalyst do not change significantly and the particles are uniform,suggesting that the catalyst has good crystal phase stability and regeneration stability.

关键词： Bagasse lignin calcium ferrite Pr doping Catalytic pyrolysis Guaiacol Rare earths

Effect of FeO concentration in sinter iron ore on reduction behavior in a hydrogen-enriched blast furnace

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International Journal of Minerals,Metallurgy and Materials 2022年第10期29卷 1820-1829页

作者： Ko-ichiro Ohno Takayuki Maeda Kazuya Kunitomo Masashi Hara Department of Materials Faculty of EngineeringKyushu University744 MotookaNishi-kuFukuoka 819-0395Japan Kashima Area East Nippon WorksNippon Steel Corporation3 HikariKashima CityIbaraki 314-0014Japan

Japan started the national project“COURSE 50”for CO_(2) reduction in the 2000s.This project aimed to establish novel technologies to reduce CO_(2) emissions with partially utilization of hydrogen in blast furnace-based ironmaking by 30%by around 2030 and use it for practical applications by 2050.The idea is that instead of coke,hydrogen is used as the reducing agent,leading to lower fossil fuel consumption in the process.It has been reported that the reduction behavior of hematite,magnetite,calcium ferrite,and slag in the sinter is different,and it is also considerably influenced by the sinter morphology.This study aimed to investigate the reduction behavior of sinters in hydrogen enriched blast furnace with different mineral morphologies in CO-CO_(2)-H2 mixed gas.As an experimental sample,two sinter samples with significantly different hematite and magnetite ratios were prepared to compare their reduction behaviors.The reduction of wustite to iron was carried out at 1000,900,and 800℃ in a CO-CO_(2)-H2 atmosphere for the mineral morphology-controlled sinter,and the following findings were obtained.The reduction rate of smaller amount of FeO led to faster increase of the reduction rate curve at the initial stage of reduction.Macro-observations of reduced samples showed that the reaction proceeded from the outer periphery of the sample toward the inside,and a reaction interface was observed where reduced iron and wustite coexisted.Micro-observations revealed three layers,namely,wustite single phase in the center zone of the sample,iron single phase in the outer periphery zone of the sample,and iron oxide-derived wustite FeO and iron,or calcium ferritederived wustite'FeO'and iron in the reaction interface zone.A two-interface unreacted core model was successfully applied for the kinetic analysis of the reduction reaction,and obtained temperature dependent expressions of the chemical reaction coefficients from each mineral phases.

关键词： hydrogen reduction wustite hematite magnetite calcium ferrite two-interface unreacted core model COURSE50

Determination method of high-temperature characteristics of iron-ore sintering based on n(Fe2O3)/n(CaO)

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Journal of Iron and Steel Research(International) 2019年第12期26卷 1257-1264页

作者： Zheng-wei Yu Li-xin Qian Hong-ming Long Yi-fan Wang Qing-min Meng Tie-jun Chun School of Metallurgical Engineering Anhui University of TechnologyMa’anshan 243002AnhuiChina Key Laboratory of Metallurgical Emission Reduction and Resources Recycling(Anhui University of Technology) Ministry of EducationMa’anshan 243002AnhuiChina

The high-temperature characteristics of iron ores play important roles in optimizing ore proportion of sintering,which are tested by using iron-ore fines and analytical reagent CaO as raw materials.Two calculation methods of CaO addition amount based on binary basicity(basicity method)and n(Fe2O3)/n(CaO)(mole ratio method),respectively,were employed to evaluate the liquid phase fluidity(LPF)and the capability of calcium ferrite formation(CCFF)of iron ores.The results show that the rule of LPF of iron ores under the mole ratio method is different from that with basicity method.The LPF measured by basicity method has a linear positive correlation with the SiO2 content,and there is no linear relationship between LPF and Al2O3 content or mass loss on ignition,which are inconsistent with the results of the previous study.And the results of CCFF with low SiO2 content(7 wt.%)based on basicity method cannot reflect the true CCFF.The mole ratio method could successfully solve this problem by reducing the effect of CaO addition amount changes caused by SiO2 content of iron ores.

关键词： Iron-ore sintering High-temperature characteristics Liquid phase fluidity calcium ferrite CaO addition amount

Reduction kinetics of MgO-doped calcium ferrites under CO-N2 atmosphere

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Journal of Iron and Steel Research(International) 2019年第12期26卷 1265-1272页

作者： Tian-xiong Wang Cheng-yi Ding Xue-wei Lv Sen-wei Xuan Gang Li Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and New Materials Chongqing UniversityChongqing 400044China School of Materials Science and Engineering Chongqing UniversityChongqing 400044China

The effect of magnesia on calcium ferrite(CaO.Fe2O3)reduction by CO was examined by isothermal thermogravimetry.Samples of calcium ferrite added with 0,2,4,and 8 wt.%magnesia(abbreviated as CF,CF2M,CF4M,and CF8M)were prepared.Phase composition was analyzed by X-ray diffraction,and the results indicated that CF2M and CF4M are reduced to lower reduction degree and with lower apparent activation energy than CF;and CF8M with more MgO.Fe2O3 is reduced to a lower degree and with more difficulty compared with CF.Reduction rate analysis revealed that CF,CF2M,CF4M,and CF8M reductions are all typical two-step reactions with the order of CF→CWF(CaO.FeO.Fe2O3)→Fe.The apparent reduction activation energies of CF,CF2M,CF4M,and CF8M are 46.89,37.30,17.30,and 29.20 kJ/mol,respectively.Sharp analysis depicted that CF2M,CF4M,and CF8M reductions are all described by 2D Avrami–Erofeev(A–E)equation(A2)in the whole process,while CF reduction is first expressed by A2 and then by 3D A–E equation(A3).Different from shrinking core model,a new kinetic model for powdery samples reduction was proposed to illustrate the relationship among reduction rates,reduction routes,and model functions.

关键词： calcium ferrite Magnesia Reduction kinetics Reduction model

Amelioration of the mineral compositions and microstructures of the special ore sinters

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Journal of Central South University of Technology 2001年第1期8卷 29-33页

作者： FU Ju ying, WANG Li guang (Department of Mineral Engineering, Central South University, Changsha 410083, China) Department of Mineral Engineering Central South University Changsha China

Mineral compositions and microstructures of fluorine bearing magnetite concentrate and vanadium titanomagnetite concentrate are studied. The results show that a boride and a catalytic oxidation agent have great effects on ameliorating the mineral compositions and microstructures of these sinters, and the catalytic agent is more effective. Comparing these two kinds of ores, the performance of fluorine bearing magnetite concentrate is better. Addition of 0.01% catalyst into fluorine bearing magnetite concentrate can increase calcium ferrite content from 15% 20% up to 34% 39%, and its microstructure changes from large cavities and thin framework into intermediate cavities and thick framework, and the microcracks disappear.

关键词： calcium ferrite catalyst vanadium titanomagnetite concentrate fluorine bearing magnetite concentrate sinter

Effect of MgO on Melting and Crystallization of CaO-Fe2O3 System

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Effect of MgO on Melting and Crystallization of CaO-Fe2O3 Sy...