Research

Jump to: Review

11 pages, 2394 KiB

Open AccessArticle

Low-Temperature CO Oxidation over CuO-CeO₂/Fe₂O₃ Catalyst: Effect of KMnO₄ Modification

by Lu Feng, Xiangdong Xing, Yueli Du, Zhenghua Shen, Hui Zhang, Liu Yang and Ming Lv

Metals 2023, 13(2), 186; https://doi.org/10.3390/met13020186 - 17 Jan 2023

Viewed by 1158

In this paper, the effect of KMnO₄ modification on the performance of CO oxidation over a CuCeO_x/Fe₂O₃ catalyst in industrial flue gas was studied. X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature-programmed reduction by H₂ (H [...] Read more.

In this paper, the effect of KMnO₄ modification on the performance of CO oxidation over a CuCeO_x/Fe₂O₃ catalyst in industrial flue gas was studied. X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature-programmed reduction by H₂ (H₂-TPR), Fourier transform infrared spectroscope (FTIR), and Raman spectra were employed to reveal the relationship between the structural properties and the performance of the catalyst. The results show that the catalytic activity could be increased by KMnO₄ modification. CuCeO_x/Fe₂O₃ modified with 0.07 mol/L KMnO₄ exhibited high activity, with a CO conversion of 78.2% at 160 °C. The modification of KMnO₄ reduced the grain size and promoted the uniform dispersion of active particles. In addition, the number of oxygen-containing functional groups increased, which could anchor metal particles and provide active oxygen species for CO oxidation. Full article

(This article belongs to the Special Issue Clean Ironmaking and Steelmaking Processes)

► Show Figures

Figure 1

15 pages, 3807 KiB

Open AccessArticle

Supersonic Shrouding Methane Mixtures for Supersonic Combustion Coherent Jets

by Fei Zhao, Tianhao Di, Rong Zhu and Wenrui Wang

Metals 2023, 13(1), 123; https://doi.org/10.3390/met13010123 - 07 Jan 2023

Cited by 1 | Viewed by 1258

Abstract

A coherent jet oxygen supply plays a key role in the process of electric arc furnace steelmaking: it provides the necessary oxygen for the smelting of molten steel and promotes the flow of the molten pool. Compared with coherent jets in current use, [...] Read more.

A coherent jet oxygen supply plays a key role in the process of electric arc furnace steelmaking: it provides the necessary oxygen for the smelting of molten steel and promotes the flow of the molten pool. Compared with coherent jets in current use, the supersonic combustion coherent jet shrouded in supersonic methane gas could improve the impact capacity and stirring intensity of the molten pool. In order to reduce the smelting cost, the characteristics of the supersonic combustion coherent jet shrouding the supersonic methane and nitrogen mixtures must be studied. Computational fluid dynamics software is used to simulate the supersonic combustion coherent jet under various methane–nitrogen mixing conditions. The six-component combustion mechanism of methane and the Eddy Dissipation Concept combustion reaction model are selected. In agreement with thermal experiments, the simulation results show that the inclusion of a small amount of nitrogen has little effect on the combustion of supersonic shrouding methane gas. However, as the nitrogen content increases, the combustion region of supersonic shrouding gas becomes shorter in length, resulting in decreases in the lengths of the high-temperature, low-density region, and the high-turbulence-intensity region. These effects weaken the ability of the shrouding gas to envelop the main oxygen jet. The potential core length of the main oxygen jet decreases significantly; this decrease first accelerates and then decelerates. These results demonstrate the feasibility of including a small amount of nitrogen (about 10 wt%) in the supersonic shrouding methane gas without substantial negative impacts on the characteristics of the supersonic combustion coherent jet. Full article

(This article belongs to the Special Issue Clean Ironmaking and Steelmaking Processes)

► Show Figures

Figure 1

8 pages, 4149 KiB

Open AccessArticle

Development of a Moving-Bed Ironmaking Process for Direct Gaseous Reduction of Iron Ore Concentrate

by Hong Yong Sohn and Syamantak Roy

Metals 2022, 12(11), 1889; https://doi.org/10.3390/met12111889 - 04 Nov 2022

Cited by 4 | Viewed by 1053

Abstract

A novel horizontal moving-bed ironmaking process has been developed at the University of Utah. This process uses iron concentrate directly without sintering or pelletization and reduces it with hydrogen in the temperature range of 500–1000 °C. The work started with the determination of [...] Read more.

A novel horizontal moving-bed ironmaking process has been developed at the University of Utah. This process uses iron concentrate directly without sintering or pelletization and reduces it with hydrogen in the temperature range of 500–1000 °C. The work started with the determination of the particle kinetics, which was then combined with diffusional effects to analyze the reduction rate of a particle bed. Based on the kinetics formulation, a mathematical model of the furnace for the proposed technology was developed for a modest industrial ironmaking operation designed to produce iron at a rate of 0.1 Mtpy. Full article

(This article belongs to the Special Issue Clean Ironmaking and Steelmaking Processes)

► Show Figures

Figure 1

12 pages, 4355 KiB

Open AccessArticle

Research on Magnesium Reduction Slag for Dephosphorization of Low-Silicon Hot Metal in Steelmaking Process

by Ming Lv, Kun Xie, Kui Xue and Zhaohui Zhang

Metals 2022, 12(10), 1617; https://doi.org/10.3390/met12101617 - 27 Sep 2022

Cited by 1 | Viewed by 1189

Abstract

The melting temperature and viscosity of magnesium reduction slag were calculated by using Factsage thermodynamic software. The composition range of the magnesium-slag-based dephosphorizing agent was analyzed by drawing a multiphase diagram of the slag system. The Box–Behnken high-temperature dephosphorization experiment was designed to [...] Read more.

The melting temperature and viscosity of magnesium reduction slag were calculated by using Factsage thermodynamic software. The composition range of the magnesium-slag-based dephosphorizing agent was analyzed by drawing a multiphase diagram of the slag system. The Box–Behnken high-temperature dephosphorization experiment was designed to study the effect of different composition of magnesium-slag-based dephosphorizers on the dephosphorization rate of the steelmaking process. The results show that magnesium slag can be used as a slag-forming agent for smelting low-silicon hot metal to promote slagging, and the effect of each factor on the phosphorus removal rate is ranked, and the results are ω(Fe₂O₃) > basicity > ω(Al₂O₃): ω(Al₂O₃) has no significant effect on the rate of phosphorus removal. When the basicity was 2.8, ω(Fe₂O₃) was 25.94%, ω(Al₂O₃) was 6.73%, and ω(MgO) was 6%, the dephosphorization rate reached a maximum of 96.7%, and the error was experimentally verified to be 2.6% from the predicted value, indicating that the model can be optimized to determine the best magnesium-slag-based dephosphorization agent and has a good prediction of dephosphorization effect. Full article

(This article belongs to the Special Issue Clean Ironmaking and Steelmaking Processes)

► Show Figures

Figure 1

18 pages, 3245 KiB

Open AccessArticle

Prediction Model of End-Point Phosphorus Content in EAF Steelmaking Based on BP Neural Network with Periodical Data Optimization

by Yuchi Zou, Lingzhi Yang, Bo Li, Zefan Yan, Zhihui Li, Shuai Wang and Yufeng Guo

Metals 2022, 12(9), 1519; https://doi.org/10.3390/met12091519 - 14 Sep 2022

Cited by 7 | Viewed by 1476

Abstract

The phosphorus (P) content of molten steel is of great importance for the quality of steel products in the electric arc furnace (EAF) steelmaking process. At present, the initial conditions of smelting process in the prediction of end-point P content are still the [...] Read more.

The phosphorus (P) content of molten steel is of great importance for the quality of steel products in the electric arc furnace (EAF) steelmaking process. At present, the initial conditions of smelting process in the prediction of end-point P content are still the core part. However, few studies focus on the influence between process data and end-point P content. In this research, the relationships between process data and end-point P content are explored by a BP neural network. Based on the theoretical analysis, influencing factors with high correlation were selected. The prediction model of P content coupled with process data and end-point P content is established. On this basis, the model is optimized with process data of oxygen supply and the time of the first addition of lime. Compared with the practical production data, the results indicate that the hit rate of the model optimized is 87.78% and 75.56% when prediction errors are within

\pm 0.004

and

\pm 0.003

of P content. The model established has achieved the effective prediction for end-point P content, and provided a reference for the control of P content in practical production. Full article

(This article belongs to the Special Issue Clean Ironmaking and Steelmaking Processes)

► Show Figures

Figure 1

13 pages, 4801 KiB

Open AccessFeature PaperArticle

Optimization of the Liquid Steel Flow Behavior in the Tundish through Water Model Experiment, Numerical Simulation and Industrial Trial

by Junda Liu, Ping Zhou, Xiaotan Zuo, Di Wu and Dongling Wu

Metals 2022, 12(9), 1480; https://doi.org/10.3390/met12091480 - 06 Sep 2022

Cited by 5 | Viewed by 1348

Abstract

A reasonable tundish flow behavior could improve liquid steel cleanliness by promoting floating and removal of the inclusions. The flow behaviors of the tundish could be obtained by water model experiments and numerical simulations, respectively. However, the difference in density between the tracer [...] Read more.

A reasonable tundish flow behavior could improve liquid steel cleanliness by promoting floating and removal of the inclusions. The flow behaviors of the tundish could be obtained by water model experiments and numerical simulations, respectively. However, the difference in density between the tracer and water in the experiment can contribute to notable errors. A new type of tracer, which is a mixture of potassium chloride (KCl) and ethanol, was proposed in this study to reduce the errors. The numerical simulation model was validated by the experimental data and its error was below 2%. By comparing the flow behaviors in seven tundishes with different inner structures obtained by simulation, it is found that the C1 can significantly reduce the dead volume ratio and C4 can improve the uniformity of liquid steel charged though each outlet. The structural strength of the baffle in C1 scheme was not considered, resulting in a crack of the baffle in the industrial trial. Industrial trials of the molten steel flow in the C4-based tundish were conducted and reported a reduction of 43.81% in the inclusions over the prototype. Full article

(This article belongs to the Special Issue Clean Ironmaking and Steelmaking Processes)

► Show Figures

Figure 1

16 pages, 5019 KiB

Open AccessArticle

Research on the Jet Characteristics and Dephosphorization Efficiency of Converter Oxygen Lance Blowing CO₂-O₂ Mixed Gas

by Guoli Wei, Changli Zhou, Shaoyan Hu, Jun Tian, Rong Zhu, Deyong Wang and Qingde Zhu

Metals 2022, 12(9), 1457; https://doi.org/10.3390/met12091457 - 30 Aug 2022

Cited by 2 | Viewed by 1332

Abstract

Utilization of CO₂ in steelmaking process has attracted extensive attention in recent years, not only because of its social benefits, but also its better metallurgical performance. Mixing CO₂ with O₂ blown by converter oxygen lance is gradually being adopted by [...] Read more.

Utilization of CO₂ in steelmaking process has attracted extensive attention in recent years, not only because of its social benefits, but also its better metallurgical performance. Mixing CO₂ with O₂ blown by converter oxygen lance is gradually being adopted by steelmaking plants, due to its potential of reducing consumption and improving steel quality. In the present research, effect of mixing CO₂ on the jet characteristics of a four-nozzle oxygen lance was studied in detail by numerical simulation, taking the combustion behavior between supersonic jets and ambient atmosphere into consideration innovatively. The simulated results showed that the combustion flame is mainly distributed in the region between multiple jets, and the high temperature flame has a noticeable influence on the low-velocity region of the jet. Due to the dilution effect of CO₂, mixing CO₂ into the oxygen jets will reduce the maximum temperature of the flame and slow down the combustion rate. With the increase of CO₂ mixing ratio, the high-temperature zone of combustion flame moves away from the lance tip significantly. At the same distance from the nozzle, although mixing CO₂ can hardly increase the velocity magnitude of the jet, but it can achieve higher dynamic pressure, indicating stronger impacting power. Then the industrial experiment of top blowing O₂-CO₂ was carried out in a 120-ton converter. During the blowing time of 120~300 s, the mixing ratio of CO₂ was 15 vol.% for better dephosphorization, and no CO₂ was mixed in the rest time of blowing. Due to the stronger stirring and better thermodynamics, the average [P] content in the final molten steel was decreased from 0.0155 wt.% to 0.0129 wt.%, achieving higher dephosphorization efficiency. Full article

(This article belongs to the Special Issue Clean Ironmaking and Steelmaking Processes)

► Show Figures

Figure 1

13 pages, 4611 KiB

Open AccessArticle

The Isolated Austenite Forming during High-Temperature Cooling and Its Influence on Pitting Corrosion Resistance in S32750 Duplex Stainless Steel

by Xiaohan Wu, Zhigang Song, Jianguo He, Zhiyi Bao, Han Feng, Wenjie Zheng and Yuliang Zhu

Metals 2022, 12(8), 1316; https://doi.org/10.3390/met12081316 - 05 Aug 2022

Viewed by 1029

Abstract

The formation mode of isolated austenite (IA) formed during high-temperature cooling and its effect on pitting corrosion resistance of S32750 DSS were investigated. As the structure formed during the high-temperature cooling process after hot rolling in S32750 duplex stainless steel (DSS), the precipitation [...] Read more.

The formation mode of isolated austenite (IA) formed during high-temperature cooling and its effect on pitting corrosion resistance of S32750 DSS were investigated. As the structure formed during the high-temperature cooling process after hot rolling in S32750 duplex stainless steel (DSS), the precipitation of isolated austenite (IA) can be considered as the combined production of temperature and cooling rates. IA generated at the ferrite (α) grain boundaries or internal α and performed the K-S crystallographic relation with the α N element enriched in IA. The redistribution of elements not only increased the concentration gradient between α/IA, but also reduced the pitting resistance equivalent number (PREN) of original austenite (γ). Scanning Kelvin probe (SKP) and Gaussian fitting proved that with prolonged corrosion time, the potential difference enlarged and local corrosion aggravated. Measured by the weight loss method, pitting resistance decreased to one-third of the solid solution state due to the existence of IA; following, the quantities, sizes, and depth of corrosion pits increased significantly. In addition to α/γ boundaries and α/α boundaries, corrosion pits preferred to initiate around IA. The IA that appeared at α grain boundaries deteriorated the pitting corrosion resistance severely. Furthermore, original austenite with decreased PREN tended to be corroded. In general, the order of pitting occurrence is displayed as follows: α-γ-IA. Full article

(This article belongs to the Special Issue Clean Ironmaking and Steelmaking Processes)

► Show Figures

Figure 1

24 pages, 5224 KiB

Open AccessArticle

Thermodynamic and Experimental Study on Migration Characteristics of Heavy Metals during the Melting Process of Incineration Fly Ash

by Yufeng Guo, Chen Gong, Lingzhi Yang, Ming Hu and Xun Hu

Metals 2022, 12(6), 1036; https://doi.org/10.3390/met12061036 - 17 Jun 2022

Cited by 1 | Viewed by 1265

Abstract

The migration characteristics of heavy metals during the melting process were one of the key factors for safe treatment and resource utilization of incineration fly ash (IFA). In this paper, the material variation of heavy metal elements of Pb, Zn, Cu, and Fe [...] Read more.

The migration characteristics of heavy metals during the melting process were one of the key factors for safe treatment and resource utilization of incineration fly ash (IFA). In this paper, the material variation of heavy metal elements of Pb, Zn, Cu, and Fe during the IFA melting process was simulated by HSC 6.0 chemistry software. The effects of melting temperature, alkalinity, atmosphere, chlorine content of raw materials, and an iron bath added to the migration characteristics, and phase transformation of selected heavy metal elements was investigated. The simulation results were also verified by experimental results. The results showed that, with the increase in temperature, the gas phase proportion of Pb, Zn, Cu, and Fe gradually increased. The alkalinity had little effect on the proportion of elements Fe and Cu in the liquid slag (LS) phase and the element Pb in the gas phase, but the increase in alkalinity could inhibit the proportion of element Zn in the gas phase. Zn mainly existed in the gas phase, and the atmosphere had little influence on the distribution of Zn. In reducing atmosphere (RA), elements Fe and Cu, which entered the liquid metal (LM) phase, were promoted, while the volatilization of Pb was restrained, which was conducive to the recovery of heavy metals. The melting process of IFA with water-washing and dechlorination had an inhibitory effect on the volatilization of Zn and Pb, but had little effect on Fe and Cu. The proportion of element Zn in the gas phase reduced from 85.84% to 9.89%. With the iron bath added in the IFA melting process, 98.42% of Cu and 82.28% of Pb entered the LM phase as metal simple substances, and 76.3% of Zn entered the gas phase as Zn (g) and ZnCl₂ (g). In the experimental verification, the distribution proportions of the four heavy metals in the gas phase, LS phase, and LM phase were consistent with the simulation results. Full article

(This article belongs to the Special Issue Clean Ironmaking and Steelmaking Processes)

► Show Figures

Figure 1

12 pages, 3332 KiB

Open AccessArticle

Evolution of Non-Metallic Inclusions in 27SiMn Steel

by Xinliang Lu, Zhaohui Zhang, Ming Lv, Xintao Li, Baomin Song and Ming Fang

Metals 2022, 12(5), 718; https://doi.org/10.3390/met12050718 - 23 Apr 2022

Cited by 3 | Viewed by 1417

Abstract

To study the evolution of non-metallic inclusions in 27SiMn steel, the 27SiMn steel produced using the LD-LF-CCM process was sampled in various stages in a steel factory. The evolutionary behavior of inclusion in various processes was systematically analyzed by scanning electron microscopy (SEM-EDS), [...] Read more.

To study the evolution of non-metallic inclusions in 27SiMn steel, the 27SiMn steel produced using the LD-LF-CCM process was sampled in various stages in a steel factory. The evolutionary behavior of inclusion in various processes was systematically analyzed by scanning electron microscopy (SEM-EDS), and the total oxygen content and nitrogen content in 27SiMn steel were measured at various production steps. On the basis of the calcium treatment for 27SiMn steel, the equilibrium reactions for Ca-Al were calculated according to the thermodynamic equilibrium model. The results showed that the types of inclusions at the start of LF stations are mainly Al₂O₃-FeO and MnS-Al₂O₃. Before calcium treatment, the inclusions are mostly calcium aluminate and CaO-MgO-Al₂O₃. Compared with the process after soft blowing, the number density of inclusions in tundish increased by 77.88%, possibly due to secondary oxidation. From the soft blowing process to the continuous casting round billet, the inclusions translate into spherical CaO-MgO-Al₂O₃-SiO₂, and a large number of CaS were observed. One part of the CaS precipitated separately, the other part was semi-wrapped with the composite inclusions. At the same time, calcium treatment increases the number density, mean diameter, and the area fraction of inclusions. The mass fraction of T.O. (total oxygen content) increased significantly after soft blowing, and the N content increased greatly from station to tundish. The change trend of N content in steel was basically consistent with that of T.O. content. It was necessary to prevent the secondary oxidation of molten steel during calcium treatment and the casting process. When the liquidus temperature of liquid steel is 1873 K, w[Al] = 0.022%, and w[Ca] in steel is controlled between 1.085 × 10⁻⁶ and 4.986 × 10⁻⁶, the Al₂O₃ inclusion degeneration effect is good. Full article

(This article belongs to the Special Issue Clean Ironmaking and Steelmaking Processes)

► Show Figures

Figure 1

Review

Jump to: Research

16 pages, 2274 KiB

Open AccessReview

Research Progress on Injection Technology in Converter Steelmaking Process

by Ming Lv, Shuangping Chen, Lingzhi Yang and Guangsheng Wei

Metals 2022, 12(11), 1918; https://doi.org/10.3390/met12111918 - 09 Nov 2022

Cited by 6 | Viewed by 1911

Abstract

During the converter steelmaking process, gas-slag-metal three-phase emulsification is realized by injecting gas to complete metallurgical tasks such as slagging, dephosphorization, decarburization, and heating. As green and intelligent development of the steel industry progresses, converter steelmaking injection technology is also constantly innovating. In [...] Read more.

During the converter steelmaking process, gas-slag-metal three-phase emulsification is realized by injecting gas to complete metallurgical tasks such as slagging, dephosphorization, decarburization, and heating. As green and intelligent development of the steel industry progresses, converter steelmaking injection technology is also constantly innovating. In this review, the types and applications of top blowing injection elements, bottom blowing injection elements, and injection the medium are reviewed. Three different types of combined blowing processes are compared. At the same time, the advantages and disadvantages of different bottom blowing elements and injection media are respectively discussed. Finally, based on the research and application status of converter injection technology, the development direction of converter steelmaking injection technology is discussed. Accelerating the innovation of converter steelmaking injection technology, especially the improvement and breakthrough of high efficiency, reductions the environmental burden, and long life technology, will play an important role in promoting the transformation and improvement of the steel industry. Full article

(This article belongs to the Special Issue Clean Ironmaking and Steelmaking Processes)

► Show Figures

Figure 1

21 pages, 4255 KiB

Open AccessReview

Study on the Characteristics of Coherent Supersonic Jet with Superheated Steam

by Xin Li, Guangsheng Wei, Rong Zhu, Bohan Tian, Ruimin Zhao and Xinyi Lan

Metals 2022, 12(5), 835; https://doi.org/10.3390/met12050835 - 13 May 2022

Cited by 3 | Viewed by 1860

Abstract

By establishing a mathematical model to simulate a mixed jet of oxygen and superheated steam from a coherent supersonic jet oxygen lance, we studied the effect of superheated steam on the fluid characteristics of the mixed jet. The model was initially verified through [...] Read more.

By establishing a mathematical model to simulate a mixed jet of oxygen and superheated steam from a coherent supersonic jet oxygen lance, we studied the effect of superheated steam on the fluid characteristics of the mixed jet. The model was initially verified through laboratory experiments prior to analyzing the fluid characteristics of the mixed jet in detail. These characteristics included the jet velocity, the temperature, the turbulent kinetic energy (TKE), and the mass distribution. The results showed that, at an ambient temperature of 1700 K, the jet velocity measured in the laboratory experiment was consistent with the fluid velocity obtained by numerical simulations, with an error of only 2.7%. In a high-temperature environment, the jet velocity of the mixed oxygen and superheated steam jet was increased, the TKE around the center jet was enhanced, the superheated steam exhibited an inhibitory effect on the combustion reaction of annular methane, and the potential core length of the coherent supersonic jet was reduced, which was conducive to methane combustion and delayed the reduction in the central jet velocity. Full article

(This article belongs to the Special Issue Clean Ironmaking and Steelmaking Processes)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Clean Ironmaking and Steelmaking Processes

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (12 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI