Special Issue "Ironmaking and Steelmaking"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: closed (31 December 2018)

Special Issue Editors

Guest Editor
Dr. Zushu Li

The University of Warwick, Coventry, United Kingdom
Website | E-Mail
Interests: high temperature reactions/phenomena of multi-component systems in metal manufacturing processes; sustainable steel manufacturing technologies; liquid metal processing; steel cleanness; mould powders for continuously casting new steel grades; energy and materials recovery in steelmaking; metal (steel and aluminum) recycling
Guest Editor
Prof. Claire Davis

The University of Warwick, Coventry, United Kingdom
Website | E-Mail
Interests: development of microstructure during processing from casting to product and the relationships between microstructure and properties (both physical and mechanical) in steels; non-destructive evaluation of microstructure and defects in metals using electromagnetic sensor techniques and modelling approaches

Special Issue Information

Dear Colleagues,

Steel is a critical material in our societies and will remain an important one for a long time into the future. In the last two decades, the world steel industry has gone through drastic changes and this is predicted to continue in the future. The Asian countries (e.g. China, India) have been dominant in the production of steel creating global over-capacity, while the steel industry in the developed countries have made tremendous efforts to reinforce its global leadership in process technology and product development, and remain  sustainable and competitive. The global steel industry is also facing various grand challenges in strict environmental regulation, new energy and materials sources, and ever increasing customer requirements for high quality steel products, which has been addressed accordingly by the global iron and steel community.

For this Special Issue, “Ironmaking and Steelmaking”, in Metals, we welcome reviews and articles from the international iron and steel community to cover the state-of-the-art of the ironmaking and steelmaking processes. This includes fundamental understanding, experimental investigation, pilot plant trials, industrial applications and big data utilization in the improvement and optimization of existing processes, and research and development in transformative technologies.

Dr. Zushu Li
Prof. Claire Davis
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Metals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Ironmaking
  • Steelmaking
  • Sustainability
  • Fundamental understanding
  • Process optimization
  • Transformative technology
  • Industrial application

Published Papers (34 papers)

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Editorial

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Open AccessEditorial
Ironmaking and Steelmaking
Metals 2019, 9(5), 525; https://doi.org/10.3390/met9050525
Received: 29 April 2019 / Accepted: 7 May 2019 / Published: 7 May 2019
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Abstract
Steel is a critical material in our society and will remain an important one for a long time into the future [...] Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)

Research

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Open AccessArticle
Modification of Non-Metallic Inclusions in Oil-Pipeline Steels by Ca-Treatment
Metals 2019, 9(4), 391; https://doi.org/10.3390/met9040391
Received: 18 January 2019 / Revised: 7 March 2019 / Accepted: 25 March 2019 / Published: 28 March 2019
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Abstract
Corrosion rate in different steel grades (including oilfield pipeline steels) is determined by the presence of non-metallic inclusions (NMI) in steels. Specifically, the effect of different inclusions on the quality of steels depends on their characteristics such as size, number, morphology, composition, and [...] Read more.
Corrosion rate in different steel grades (including oilfield pipeline steels) is determined by the presence of non-metallic inclusions (NMI) in steels. Specifically, the effect of different inclusions on the quality of steels depends on their characteristics such as size, number, morphology, composition, and physical properties, as well as their location in the steel matrix. Therefore, the optimization and control of NMI in steels are very important today to obtain an improvement of the material properties of the final steel products. It is well known that a Ca-treatment of liquid steels in ladle before casting is an effective method for modification of non-metallic inclusions for improvement of the steel properties. Therefore, the NMI characteristics were evaluated in industrial steel samples of low carbon Ca-treated steel used for production of oil-pipelines. An electrolytic extraction technique was used for extraction of NMI from the steel samples followed by three-dimensional investigations of different inclusions and clusters by using SEM in combination with EDS. Moreover, the number and compositions of corrosion active non-metallic inclusions were estimated in hot rolled steel samples from two different heats. Finally, the corrosion resistance of these steels can be discussed depending on the characteristics of non-metallic inclusions present in the steel. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Comparison of Energy Consumption and CO2 Emission for Three Steel Production Routes—Integrated Steel Plant Equipped with Blast Furnace, Oxygen Blast Furnace or COREX
Metals 2019, 9(3), 364; https://doi.org/10.3390/met9030364
Received: 31 December 2018 / Revised: 27 February 2019 / Accepted: 20 March 2019 / Published: 21 March 2019
Cited by 1 | PDF Full-text (3761 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
High CO2 emissions and energy consumption have greatly restricted the development of China’s iron and steel industry. Two alternative ironmaking processes, top gas recycling-oxygen blast furnace (TGR-OBF) and COREX®, can reduce CO2 emissions and coking coal consumption in the [...] Read more.
High CO2 emissions and energy consumption have greatly restricted the development of China’s iron and steel industry. Two alternative ironmaking processes, top gas recycling-oxygen blast furnace (TGR-OBF) and COREX®, can reduce CO2 emissions and coking coal consumption in the steel industry when compared with a conventional blast furnace (BF). To obtain parameters on the material flow of these processes, two static process models for TGR-OBF and COREX were established. Combining the operating data from the Jingtang steel plant with established static process models, this research presents a detailed analysis of the material flows, metallurgical gas generation and consumption, electricity consumption and generation, comprehensive energy consumption, and CO2 emissions of three integrated steel plants (ISP) equipped with the BF, TGR-OBF, and COREX, respectively. The results indicated that the energy consumption of an ISP with the TGR-OBF was 16% and 16.5% lower than that of a conventional ISP and an ISP with the COREX. Compared with a conventional ISP, the coking coal consumption in an ISP with the TGR-OBF and an ISP with the COREX were reduced by 39.7% and 100% respectively. With the International Energy Agency factor, the ISP with the TGR-OBF had the lowest net CO2 emissions, which were 10.8% and 35.0% lower than that of a conventional ISP and an ISP with the COREX. With the China Grid factor, the conventional ISP had the lowest net CO2 emissions—2.8% and 24.1% lower than that of an ISP with the TGR-OBF and an ISP with the COREX, respectively. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Model Development for Refining Rates in Oxygen Steelmaking: Impact and Slag-Metal Bulk Zones
Metals 2019, 9(3), 309; https://doi.org/10.3390/met9030309
Received: 22 December 2018 / Revised: 28 February 2019 / Accepted: 2 March 2019 / Published: 8 March 2019
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Abstract
A new approach has been adopted to predict the contribution of the impact and slag-metal bulk zones to the refining rates of impurities in a top blown oxygen steelmaking process. The knowledge pertaining to the behavior of top-jets and bottom stirring plumes (water [...] Read more.
A new approach has been adopted to predict the contribution of the impact and slag-metal bulk zones to the refining rates of impurities in a top blown oxygen steelmaking process. The knowledge pertaining to the behavior of top-jets and bottom stirring plumes (water model and industrial studies) was adapted. For the impact zone, the surface renewal generated by the top jet as well as bottom stirring plumes is incorporated in the current model, whereas in the case of slag-metal bulk zones the surface renewal is caused solely by the bottom stirring plumes. This approach helped in achieving a more explicit use of process parameters in quantifying the slag formation. The results suggest a minor contribution of these two zones to the overall refining of impurities throughout the oxygen blow. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessFeature PaperArticle
Inclusions Control and Refining Slag Optimization for Fork Flat Steel
Metals 2019, 9(2), 253; https://doi.org/10.3390/met9020253
Received: 20 December 2018 / Revised: 11 February 2019 / Accepted: 16 February 2019 / Published: 20 February 2019
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Abstract
In order to investigate the causes of the large number of cracks and porosities formed in 33MnCrTiB fork flat steel produced by a special steel plant, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) analysis, and large sample electrolysis of the obtained steel [...] Read more.
In order to investigate the causes of the large number of cracks and porosities formed in 33MnCrTiB fork flat steel produced by a special steel plant, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) analysis, and large sample electrolysis of the obtained steel samples were carried out in different steps of the steelmaking processes. The main micro-inclusions in the fork flat steel samples were Al2O3, CaO-MgO-Al2O3-SiO2, and TiN, and the macro-inclusions were mainly Al2O3, CaO-Al2O3, CaO-Al2O3-SiO2-TiO2, and CaO-MgO-Al2O3-SiO2-TiO2-(K2O) systems which originated from the ladle slag and mold flux in the production process. In order to reduce the number of micro-inclusions effectively, the control range of components in the refining slag was confirmed by the thermodynamic calculation, where the mass ratio of CaO/Al2O3 should be in the range of 1.85–1.92, and the mass fraction of SiO2 and MgO should be controlled to 7.5–20% and 6–8%, respectively. In addition, the numbers of macro-inclusions in the flat steel should be effectively reduced by optimizing the flow field of mold and preventing the secondary oxidation, and the flat steel quality problems caused by the inclusions can be improved by the optimization process above. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Desiliconisation and Dephosphorisation Behaviours of Various Oxygen Sources in Hot Metal Pre-Treatment
Metals 2019, 9(2), 251; https://doi.org/10.3390/met9020251
Received: 25 January 2019 / Revised: 15 February 2019 / Accepted: 17 February 2019 / Published: 20 February 2019
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Abstract
In order to obtain a better understanding of the efficiencies of desiliconisation and dephosphorisation reactions during hot metal pretreatment in an open ladle, a number of simulation experiments were carried out with various oxygen sources. Three types of solid oxygen materials (sintered return [...] Read more.
In order to obtain a better understanding of the efficiencies of desiliconisation and dephosphorisation reactions during hot metal pretreatment in an open ladle, a number of simulation experiments were carried out with various oxygen sources. Three types of solid oxygen materials (sintered return ore, scale briquette and fine mill scale) were carefully investigated as hot metal pre-treatment agents, evaluating their desiliconisation and dephosphorisation efficiencies. The method applied for supplying gaseous oxygen was also assessed. The comparison between top blowing and injection methods indicated that injected oxygen gas is more advantageous for desiliconisation, while top-blown oxygen gas is favourable for dephosphorisation. The obtained information on the characteristics of gaseous oxygen can be used for the optimisation of blowing patterns, in order to improve the efficiency of the hot metal pre-treatment. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Formation of Surface Depression during Continuous Casting of High-Al TRIP Steel
Metals 2019, 9(2), 204; https://doi.org/10.3390/met9020204
Received: 31 December 2018 / Revised: 26 January 2019 / Accepted: 5 February 2019 / Published: 9 February 2019
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Abstract
High aluminum transformation-induced plasticity (TRIP) steels offer a unique combination of high tensile strength and ductility, high impact energy absorption and good formability. The surface of the slab is prone to depressions and longitudinal cracks during continuous casting due to the high Al [...] Read more.
High aluminum transformation-induced plasticity (TRIP) steels offer a unique combination of high tensile strength and ductility, high impact energy absorption and good formability. The surface of the slab is prone to depressions and longitudinal cracks during continuous casting due to the high Al content in steels. Surface depressions of the 1.35 wt.% Al-TRIP steel slab in a steel works were investigated by scanning electronic microscopy (SEM) and mold fluxes with different Al2O3/SiO2 ratios were researched by thermodynamic calculations and high-temperature static balance experiments. The results show that some micro-cracks were distributed along the grain boundary in the surface depression of the slab. Inclusions containing K and Na, which were probably from mold flux, were found in the depression samples. Meanwhile, the components of reactive mold flux showed significant variation in their chemical composition during the continuous casting process of the Al-TRIP steel. A large number of depressions and irregular oscillation marks on the Al-TRIP steel slab surface were generated due to serious deterioration in the physical properties of the mold flux. Since the TRIP steel is a typical hypo-peritectic steel, the overly large thermal contraction and volume contraction during initial solidification is the intrinsic cause of surface depression. The change of mold flux properties during casting aggravates the formation of depressions. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Devolatilization Kinetics of Different Types of Bio-Coals Using Thermogravimetric Analysis
Metals 2019, 9(2), 168; https://doi.org/10.3390/met9020168
Received: 17 January 2019 / Revised: 28 January 2019 / Accepted: 29 January 2019 / Published: 1 February 2019
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Abstract
The interest of the steel industry in utilizing bio-coal (pre-treated biomass) as CO2-neutral carbon in iron-making is increasing due to the need to reduce fossil CO2 emission. In order to select a suitable bio-coal to be contained in agglomerates with [...] Read more.
The interest of the steel industry in utilizing bio-coal (pre-treated biomass) as CO2-neutral carbon in iron-making is increasing due to the need to reduce fossil CO2 emission. In order to select a suitable bio-coal to be contained in agglomerates with iron oxide, the current study aims at investigating the thermal devolatilization of different bio-coals. A thermogravimetric analyzer (TGA) equipped with a quadrupole mass spectrometer (QMS) was used to monitor the weight loss and off-gases during non-isothermal tests with bio-coals having different contents of volatile matter. The samples were heated in an inert atmosphere to 1200 °C at three different heating rates: 5, 10, and 15 °C/min. H2, CO, and hydrocarbons that may contribute to the reduction of iron oxide if contained in the self-reducing composite were detected by QMS. To explore the devolatilization behavior for different materials, the thermogravimetric data were evaluated by using the Kissinger– Akahira–Sonuse (KAS) iso-conversional model. The activation energy was determined as a function of the conversion degree. Bio-coals with both low and high volatile content could produce reducing gases that can contribute to the reduction of iron oxide in bio-agglomerates and hot metal quality in the sustained blast furnace process. However, bio-coals containing significant amounts of CaO and K2O enhanced the devolatilization and released the volatiles at lower temperature. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Occupational Exposure to Fine Particles and Ultrafine Particles in a Steelmaking Foundry
Metals 2019, 9(2), 163; https://doi.org/10.3390/met9020163
Received: 30 December 2018 / Revised: 27 January 2019 / Accepted: 28 January 2019 / Published: 1 February 2019
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Abstract
Several studies have shown an increased mortality rate for different types of tumors, respiratory disease and cardiovascular morbidity associated with foundry work. Airborne particles were investigated in a steelmaking foundry using an electric low-pressure impactor (ELPI+™), a Philips Aerasense Nanotracer and traditional sampling [...] Read more.
Several studies have shown an increased mortality rate for different types of tumors, respiratory disease and cardiovascular morbidity associated with foundry work. Airborne particles were investigated in a steelmaking foundry using an electric low-pressure impactor (ELPI+™), a Philips Aerasense Nanotracer and traditional sampling equipment. Determination of metallic elements in the collected particles was carried out by inductively coupled plasma mass spectrometry. The median of ultrafine particle (UFP) concentration was between 4.91 × 103 and 2.33 × 105 part/cm3 (max. 9.48 × 106 part/cm3). Background levels ranged from 1.97 × 104 to 3.83 × 104 part/cm3. Alveolar and deposited tracheobronchial surface area doses ranged from 1.3 × 102 to 8.7 × 103 mm2, and 2.6 × 101 to 1.3 × 103 mm2, respectively. Resulting inhalable and respirable fraction and metallic elements were below limit values set by Italian legislation. A variable concentration of metallic elements was detected in the different fractions of UFPs in relation to the sampling site, the emission source and the size range. This data could be useful in order to increase the knowledge about occupational exposure to fine and ultrafine particles and to design studies aimed to investigate early biological effects associated with the exposure to particulate matter in the foundry industries. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Effect of Substituting CaO with BaO and CaO/Al2O3 Ratio on the Viscosity of CaO–BaO–Al2O3–CaF2–Li2O Mold Flux System
Metals 2019, 9(2), 142; https://doi.org/10.3390/met9020142
Received: 20 December 2018 / Revised: 25 January 2019 / Accepted: 26 January 2019 / Published: 28 January 2019
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Abstract
The effect of substituting CaO with BaO and CaO/Al2O3 ratio on the viscosity of CaO–BaO–Al2O3–CaF2–Li2O mold flux system was studied by rotational viscosity method. The results showed that the viscosity increased with [...] Read more.
The effect of substituting CaO with BaO and CaO/Al2O3 ratio on the viscosity of CaO–BaO–Al2O3–CaF2–Li2O mold flux system was studied by rotational viscosity method. The results showed that the viscosity increased with increasing BaO as a substitute for CaO, while the viscosity decreased with the increase in CaO/Al2O3 ratio. The viscous activation energy of the slags is from 92.1 kJ·mol−1 to 133.4 kJ·mol−1. Either the Arhenius or the Weymann–Frenkel equation can be applied to establish the viscosity prediction model. In this paper, the Weymann–Frenkel equation and a new optical basicity with regard to Al2O3 as an acidic oxide were applied to the modified NPL model for predicting the viscosity of CaO–BaO–Al2O3–CaF2–Li2O mold flux system. The estimated viscosity is in good agreement with the measured viscosity. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Vertical Section Observation of the Solid Flow in a Blast Furnace with a Cutting Method
Metals 2019, 9(2), 127; https://doi.org/10.3390/met9020127
Received: 6 December 2018 / Revised: 17 January 2019 / Accepted: 21 January 2019 / Published: 25 January 2019
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Abstract
The solid flow plays an important role in blast furnace (BF) ironmaking. In the paper, the descending behavior of solid flow in BFs was investigated by a cold experimental BF model and numerical simulation via the discrete element method (DEM). To eliminate the [...] Read more.
The solid flow plays an important role in blast furnace (BF) ironmaking. In the paper, the descending behavior of solid flow in BFs was investigated by a cold experimental BF model and numerical simulation via the discrete element method (DEM). To eliminate the flat wall effect on the structure of solid flow in lab observations, a cutting method was developed to observe the vertical section of the solid flow by inserting a transparent plate into the experimental BF model. Both the experimental and numerical results indicated that plug flow is the main solid flow pattern in the upper and middle zones of BFs during burden descending. Meanwhile, a slight convergence flow and a deadman zone form at the lower part of the bosh. In addition, the boundary between the plug flow and convergence flow in BFs was determined by analyzing the velocity of the burden in vertical directions and the Wilcox–Swailes coefficient (Uws). The results indicated that the Uws can be defined as a critical value to determine the solid flow patterns. When Uws ≥ 0.65, the plug flow is dominant. When Uws < 0.65, the convergence flow is dominant. The findings may have important implications to understand the structure of the solid flow in BFs. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessFeature PaperArticle
Characterisation of the Solidification of a Molten Steel Surface Using Infrared Thermography
Metals 2019, 9(2), 126; https://doi.org/10.3390/met9020126
Received: 10 December 2018 / Revised: 15 January 2019 / Accepted: 23 January 2019 / Published: 24 January 2019
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Abstract
Infrared thermography provides an option for characterising surface reactions and their effects on the solidification of steel under different gas atmospheres. In this work, infrared thermography has been used during solidification of Twin Induced Plasticity (TWIP) steel in argon, carbon dioxide and nitrogen [...] Read more.
Infrared thermography provides an option for characterising surface reactions and their effects on the solidification of steel under different gas atmospheres. In this work, infrared thermography has been used during solidification of Twin Induced Plasticity (TWIP) steel in argon, carbon dioxide and nitrogen atmospheres using a confocal scanning laser microscope (CSLM). It was found that surface reactions resulted in a solid oxide film (in carbon dioxide) and decarburisation, along with surface graphite formation (in nitrogen). In both cases the emissivity and, hence, the cooling rate of the steel was affected in distinct ways. Differences in nucleation conditions (free surface in argon compared to surface oxide/graphite in carbon dioxide/nitrogen) as well as chemical composition changes (decarburisation) affected the liquidus and solidus temperatures, which were detected by thermal imaging from the thermal profile measured. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Kinetic Studies on Gas-Based Reduction of Vanadium Titano-Magnetite Pellet
Metals 2019, 9(1), 95; https://doi.org/10.3390/met9010095
Received: 5 January 2019 / Revised: 13 January 2019 / Accepted: 14 January 2019 / Published: 16 January 2019
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Abstract
Vanadium titano-magnetite (VTM) is a significant resource in China—analysis shows that China possesses approximately 10 billion tons of VTM. In this study, we characterize VTM’s isothermal reduction mechanisms in the mixture of H2, CO, and N2 where the variables considered [...] Read more.
Vanadium titano-magnetite (VTM) is a significant resource in China—analysis shows that China possesses approximately 10 billion tons of VTM. In this study, we characterize VTM’s isothermal reduction mechanisms in the mixture of H2, CO, and N2 where the variables considered include reduction time, reduction temperature, gas composition, and pellet size. The kinetics of the reduction process were studied following a shrinking core model. The results indicate that the reduction degree of oxidized VTM pellets increases with increases of reduction time and reduction temperature but decreases with increasing pellet size. Moreover, we found that an increase of H2/(H2 + CO) ratio induced an increase of the reduction degree. We discuss the transformation of main Ti-bearing mineral phases, and we consider the most probable reaction mechanism. For the entire reduction process, the kinetic results confirm the existence of an early and later stages that are controlled by interface chemical reaction and diffusion, respectively. Furthermore, the results show that the diffusion-control step can be observably shortened via decreased pellet size because a thinner product layer is formed during the reduction process. Our study thus provides a valuable technical basis for industrial applications of VTM. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Structure of Solidified Films of CaO-SiO2-Na2O Based Low-Fluorine Mold Flux
Metals 2019, 9(1), 93; https://doi.org/10.3390/met9010093
Received: 4 December 2018 / Revised: 8 January 2019 / Accepted: 11 January 2019 / Published: 16 January 2019
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Abstract
As an essential synthetic material used in the continuous casting of steels, mold fluxes improve the surface quality of steel slabs. In this study, a CaO-SiO2-Na2O-based low-fluorine mold flux was solidified by an improved water-cooled copper probe with different [...] Read more.
As an essential synthetic material used in the continuous casting of steels, mold fluxes improve the surface quality of steel slabs. In this study, a CaO-SiO2-Na2O-based low-fluorine mold flux was solidified by an improved water-cooled copper probe with different temperatures of molten flux and different probe immersion times. The heat flux through solid films and the film structures were calculated and inspected, respectively. Internal cracks (formed in the glassy layer of films during solidification) were observed. The formation and evolution of those cracks contributed to the unstable heat flux density. The roughness of the surface in contact with the water-cooled copper probe formed as films were still glassy and the roughness had no causal relationship with crystallization or devitrification. Combeite with columnar and faceted dendritic shapes were the main crystal in the film. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Effects of Fe2O3 on Reduction Process of Cr-Containing Solid Waste Self-Reduction Briquette and Relevant Mechanism
Metals 2019, 9(1), 51; https://doi.org/10.3390/met9010051
Received: 21 November 2018 / Revised: 24 December 2018 / Accepted: 29 December 2018 / Published: 7 January 2019
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Abstract
High-temperature quench method, scanning electron microscope-energy dispersive spectroscopy (SEM-EDS), and thermodynamic analysis were adopted to study the effects of Fe2O3 on reduction process of Cr-containing solid waste self-reduction briquette (Cr-RB). Moreover, the relevant mechanism was also studied. The results clearly [...] Read more.
High-temperature quench method, scanning electron microscope-energy dispersive spectroscopy (SEM-EDS), and thermodynamic analysis were adopted to study the effects of Fe2O3 on reduction process of Cr-containing solid waste self-reduction briquette (Cr-RB). Moreover, the relevant mechanism was also studied. The results clearly showed that the addition of Fe2O3 decreased the chromium-iron ratio (Cr/(Fe + Cr)) of Cr-RB itself and promoted the reduction of chrome oxide in the Cr-containing solid wastes such as stainless steel slag and dust. A large number of Fe-C alloy droplets generated in the lower temperature could decrease the activity of reduced chromium by in situ dissolution and the reduction of Cr-oxide was accelerated. Rapid separation of metal and slag could be achieved at a relatively lower temperature, which was very beneficial to the efficient recovery of Cr. Finally, the corresponding mechanism diagram was presented. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Measurement of Molten Steel Velocity near the Surface and Modeling for Transient Fluid Flow in the Continuous Casting Mold
Metals 2019, 9(1), 36; https://doi.org/10.3390/met9010036
Received: 11 December 2018 / Revised: 23 December 2018 / Accepted: 29 December 2018 / Published: 4 January 2019
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Abstract
In the current work, a rod deflection method (RDM) is conducted to measure the velocity of molten steel near the surface in continuous casting (CC) mold. With the experimental measurement, the flow velocity and direction of molten steel can be obtained. In addition, [...] Read more.
In the current work, a rod deflection method (RDM) is conducted to measure the velocity of molten steel near the surface in continuous casting (CC) mold. With the experimental measurement, the flow velocity and direction of molten steel can be obtained. In addition, a mathematical model combining the computational fluid dynamics (CFD) and discrete phase method (DPM) has been developed to calculate the transient flow field in a CC mold. The simulation results are compared and validated with the plant measurement results. Reasonable agreements between the measured and simulated results are obtained, both in the trends and magnitudes for the flow velocities of molten steel near the mold surface. Based on the measured and calculated results, the velocity of molten steel near the surface in the mold increases with increasing casting speed and the casting speed can change the flow pattern in the mold. Furthermore, three different types of flow patterns of molten steel in the mold can be obtained. The pattern A is the single-roll-flow (SRF) and the pattern C is the double-roll-flow (DRF). The pattern B is a transition state between DRF and SRF, which is neither cause the vortices nor excessive surface velocity on the meniscus, so the slag entrainment rarely occurs. Argon gas injection can slow down the molten steel velocity and uplift the jet zone, due to the buoyancy of bubbles. Combination of the measurement and numerical simulation is an effective tool to investigate the transient flow behavior in the CC mold and optimize the actual operation parameters of continuous casting to avoid the surface defects of the automobile outer panels. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Enhancing the Reduction of High-Aluminum Iron Ore by Synergistic Reducing with High-Manganese Iron Ore
Metals 2019, 9(1), 15; https://doi.org/10.3390/met9010015
Received: 29 November 2018 / Revised: 19 December 2018 / Accepted: 19 December 2018 / Published: 22 December 2018
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Abstract
How to utilize low grade complex iron resources is an issue that has attracted much attention due to the continuous and huge consumption of iron ores in China. High-aluminum iron ore is a refractory resource and is difficult to upgrade by separating iron [...] Read more.
How to utilize low grade complex iron resources is an issue that has attracted much attention due to the continuous and huge consumption of iron ores in China. High-aluminum iron ore is a refractory resource and is difficult to upgrade by separating iron and alumina. An innovative technology involving synergistic reducing and synergistic smelting a high-aluminum iron ore containing 41.92% Fetotal, 13.74% Al2O3, and 13.96% SiO2 with a high-manganese iron ore assaying 9.24% Mntotal is proposed. The synergistic reduction process is presented and its enhancing mechanism is discussed. The results show that the generation of hercynite (FeAl2O4) and fayalite (Fe2SiO4) leads to a low metallization degree of 66.49% of the high-aluminum iron ore. Over 90% of the metallization degree is obtained by synergistic reducing with 60% of the high-manganese iron ore. The mechanism of synergistic reduction can be described as follows: MnO from the high-manganese ore chemically combines with Fe2SiO4 and FeAl2O4 to generate Mn2SiO4, MnAl2O4 and FeO, resulting in higher activity of FeO, which can be reduced to Fe in a CO atmosphere. The main products of the synergistic reduction process consist of Fe, Mn2SiO4, and MnAl2O4. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Thermal Behavior of Hydrated Iron Sulfate in Various Atmospheres
Metals 2018, 8(12), 1084; https://doi.org/10.3390/met8121084
Received: 19 November 2018 / Revised: 12 December 2018 / Accepted: 13 December 2018 / Published: 19 December 2018
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Abstract
Iron sulfate, in particular FeSO4·7H2O, is derived from titanium dioxide production and the steel pickling process. Regarding TiO2 manufacturing, the amount of the resultant FeSO4·7H2O can be as high as 6 tons per ton [...] Read more.
Iron sulfate, in particular FeSO4·7H2O, is derived from titanium dioxide production and the steel pickling process. Regarding TiO2 manufacturing, the amount of the resultant FeSO4·7H2O can be as high as 6 tons per ton of produced TiO2, leading to a huge amount of ferrous sulfate heptahydrate, which is considered an environmental and economic concern for the titanium dioxide industry in European countries. The present paper focuses on the thermal treatment of ferrous sulfate (heptahydrate and monohydrate) samples under different conditions. Nonisothermal thermogravimetric (TG) analysis was used to study the behavior of iron sulfate samples at temperatures of up to 1000 °C in Cl2 + O2, O2, and N2 atmospheres. Results showed that the dehydration of iron sulfate heptahydrate in nitrogen started at room temperature and resulted in iron sulfate tetrahydrate (FeSO4·4H2O). The ferrous sulfate monohydrate (FeSO4·H2O) was formed at temperatures close to 150 °C, while the anhydrous ferrous sulfate (FeSO4) was obtained when the samples were heated in nitrogen at over 225 °C. The kinetic features of FeSO4 decomposition into Fe2O3 were revealed under isothermal conditions at temperatures ranging from 500 to 575 °C. The decomposition of iron sulfate was characterized by an apparent activation energy of around 250 kJ/mol, indicating a significant temperature effect on the decomposition process. The obtained powder iron oxide could be directed to the agglomeration unit of iron and the steelmaking process. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
A Further Evaluation of the Coupling Relationship between Dephosphorization and Desulfurization Abilities or Potentials for CaO-based Slags: Influence of Slag Chemical Composition
Metals 2018, 8(12), 1083; https://doi.org/10.3390/met8121083
Received: 20 November 2018 / Revised: 16 December 2018 / Accepted: 17 December 2018 / Published: 19 December 2018
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Abstract
The coupling relationships between dephosphorization and desulfurization abilities or potentials for CaO–FeO–Fe2O3–Al2O3–P2O5 slags over a large variation range of slag oxidization ability during the secondary refining process of molten steel have been [...] Read more.
The coupling relationships between dephosphorization and desulfurization abilities or potentials for CaO–FeO–Fe2O3–Al2O3–P2O5 slags over a large variation range of slag oxidization ability during the secondary refining process of molten steel have been proposed by the present authors as log L P + 5 log L S or log C PO 4 3 + log C S 2 in the reducing zone and as log L P + log L S 5 log N Fe t O or log C PO 4 3 + log C S 2 log N FeO in the oxidizing zone based on the ion and molecule coexistence theory (IMCT). In order to further verify the validation and feasibility of the proposed coupling relationships, the effects of chemical composition of the CaO-based slags are provided. The chemical composition of slags was described by three group parameters including reaction abilities of components represented by the mass action concentrations N i , two kinds of slag basicity as simplified complex basicity ( %   CaO ) / [ ( %   P 2 O 5 ) + ( %   Al 2 O 3 ) ] and optical basicity Λ , and the comprehensive effect of iron oxides FetO and basic oxide CaO. Comparing with the strong effects of chemical composition of the CaO-based slags on dephosphorization and desulfurization abilities or potentials, the proposed coupling relationships have been confirmed to not only be independent of slag oxidization ability as expected but also irrelevant to the aforementioned three groups of parameters for representing the chemical composition of the CaO-based slags. Increasing temperature from 1811 to 1927 K (1538 to 1654 °C) can result in a decreasing tendency of the proposed coupling relationships. In terms of the proposed coupling relationships, chemical composition of slags or fluxes with assigned dephosphorization ability or potential can be theoretically designed or optimized from its desulfurization ability or potential, and vice versa. Considering the large difference of magnitude between phosphate capacity C PO 4 3 and sulfide capacity C S 2 , the proposed coupling relationships between dephosphorization and desulfurization abilities for CaO-based slags are recommended to design or optimize chemical composition of slags. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Distribution Ratio of Sulfur between CaO-SiO2-Al2O3-Na2O-TiO2 Slag and Carbon-Saturated Iron
Metals 2018, 8(12), 1068; https://doi.org/10.3390/met8121068
Received: 28 November 2018 / Revised: 11 December 2018 / Accepted: 12 December 2018 / Published: 15 December 2018
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Abstract
To explore the feasibility of hot metal desulfurization using red mud, the sulfur distribution ratio (LS) between CaO-SiO2-Al2O3-Na2O-TiO2 slag and carbon-saturated iron is evaluated in this paper. First, the theoretical liquid [...] Read more.
To explore the feasibility of hot metal desulfurization using red mud, the sulfur distribution ratio (LS) between CaO-SiO2-Al2O3-Na2O-TiO2 slag and carbon-saturated iron is evaluated in this paper. First, the theoretical liquid areas of the CaO-SiO2-Al2O3 (-Na2O-TiO2) slag are discussed and the fluxing effects of Al2O3, Na2O, and TiO2 are confirmed. Then, LS is measured via slag-metal equilibrium experiments. The experimental results show that LS significantly increases with the increase of temperature, basicity, and Na2O content, whereas it decreases with the increase of Al2O3 and TiO2 content. Na2O in the slag will volatilize with high temperatures and reducing conditions. Furthermore, based on experimental data for the sulfur distribution ratio between CaO-SiO2-Al2O3-Na2O-TiO2 slag and the carbon-saturated iron, the following fitting formula is obtained: log L S = 45.584 Λ + 10568.406 17184.041 Λ T 8.529 Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Thermodynamic of Liquid Iron Ore Reduction by Hydrogen Thermal Plasma
Metals 2018, 8(12), 1051; https://doi.org/10.3390/met8121051
Received: 9 November 2018 / Revised: 3 December 2018 / Accepted: 4 December 2018 / Published: 11 December 2018
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Abstract
The production of iron using hydrogen as a reducing agent is an alternative to conventional iron- and steel-making processes, with an associated decrease in CO2 emissions. Hydrogen plasma smelting reduction (HPSR) of iron ore is the process of using hydrogen in a [...] Read more.
The production of iron using hydrogen as a reducing agent is an alternative to conventional iron- and steel-making processes, with an associated decrease in CO2 emissions. Hydrogen plasma smelting reduction (HPSR) of iron ore is the process of using hydrogen in a plasma state to reduce iron oxides. A hydrogen plasma arc is generated between a hollow graphite electrode and liquid iron oxide. In the present study, the thermodynamics of hydrogen thermal plasma and the reduction of iron oxide using hydrogen at plasma temperatures were studied. Thermodynamics calculations show that hydrogen at high temperatures is atomized, ionized, or excited. The Gibbs free energy changes of iron oxide reductions indicate that activated hydrogen particles are stronger reducing agents than molecular hydrogen. Temperature is the main influencing parameter on the atomization and ionization degree of hydrogen particles. Therefore, to increase the hydrogen ionization degree and, consequently, increase of the reduction rate of iron ore particles, the reduction reactions should take place in the plasma arc zone due to the high temperature of the plasma arc in HPSR. Moreover, the solubility of hydrogen in slag and molten metal are studied and the sequence of hematite reduction reactions is presented. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Kinetics of the Volume Shrinkage of a Magnetite/Carbon Composite Pellet during Solid-State Carbothermic Reduction
Metals 2018, 8(12), 1050; https://doi.org/10.3390/met8121050
Received: 21 October 2018 / Revised: 5 November 2018 / Accepted: 1 December 2018 / Published: 11 December 2018
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Abstract
The volume shrinkage evolution of a magnetite iron ore/carbon composite pellet during solid-state isothermal reduction was investigated. For the shrinkage, the apparent activation energy and mechanism were obtained based on the experimental results. It was found that the volume shrinkage highly depended on [...] Read more.
The volume shrinkage evolution of a magnetite iron ore/carbon composite pellet during solid-state isothermal reduction was investigated. For the shrinkage, the apparent activation energy and mechanism were obtained based on the experimental results. It was found that the volume shrinkage highly depended on the reduction temperature and on dwell time. The volume shrinkage of the pellet increased with the increasing reduction temperature, and the rate of increment was fast during the first 20 min of reduction. The shrinkage of the composite pellet was mainly due to the weight loss of carbon and oxygen, the sintering growth of gangue oxides and metallic iron particles, and the partial melting of the gangue phase at high temperature. The shrinkage apparent activation energy was different depending on the time range. During the first 20 min, the shrinkage apparent activation energy was 51,313 J/mol. After the first 20 min, the apparent activation energy for the volume shrinkage was only 19,697 J/mol. The change of the reduction rate-controlling step and the automatic sintering and reconstruction of the metallic iron particles and gangue oxides in the later reduction stage were the main reasons for the aforementioned time-dependent phenomena. The present work could provide a unique scientific index for the illustration of iron ore/carbon composite pellet behavior during solid-state carbothermic reduction. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Non-Destructive Evaluation of Steel Surfaces after Severe Plastic Deformation via the Barkhausen Noise Technique
Metals 2018, 8(12), 1029; https://doi.org/10.3390/met8121029
Received: 18 November 2018 / Revised: 30 November 2018 / Accepted: 4 December 2018 / Published: 6 December 2018
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Abstract
This paper reports about the non-destructive evaluation of surfaces after severe shot peening via the Barkhausen noise technique. Residuals stresses and the corresponding Almen intensity, as well as microstructure alterations, are correlated with the Barkhausen noise signal and its extracted features. It was [...] Read more.
This paper reports about the non-destructive evaluation of surfaces after severe shot peening via the Barkhausen noise technique. Residuals stresses and the corresponding Almen intensity, as well as microstructure alterations, are correlated with the Barkhausen noise signal and its extracted features. It was found that residual stresses as well as the Barkhausen noise exhibit a valuable anisotropy. For this reason, the relationship between the Barkhausen noise and stress state is more complicated. On the other hand, the near-the-surface layer exhibits a remarkable deformation induced softening, expressed in terms of the microhardness and the corresponding crystalline size. Such an effect explains the progressive increase of the Barkhausen noise emission along with the shot-peening time. Therefore, the Barkhausen noise can be considered as a promising technique capable of distinguishing between the variable regimes of severe shoot peening. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Influence of Al Content on the Inclusion-Microstructure Relationship in the Heat-Affected Zone of a Steel Plate with Mg Deoxidation after High-Heat-Input Welding
Metals 2018, 8(12), 1027; https://doi.org/10.3390/met8121027
Received: 21 November 2018 / Revised: 2 December 2018 / Accepted: 3 December 2018 / Published: 6 December 2018
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Abstract
The effects of Al content on inclusions, microstructures, and heat-affected zone (HAZ) toughness in a steel plate with Mg deoxidation have been investigated by using simulated high-heat-input welding and an automated feature system. The studies indicated that the main kind of oxysulfide complex [...] Read more.
The effects of Al content on inclusions, microstructures, and heat-affected zone (HAZ) toughness in a steel plate with Mg deoxidation have been investigated by using simulated high-heat-input welding and an automated feature system. The studies indicated that the main kind of oxysulfide complex inclusions in two steels without and with Al addition were both MgO-MnS. The number densities and mean sizes of inclusions were 96.65 mm−2 and 3.47 μm, 95.03 mm−2 and 2.03 μm, respectively. The morphologies of MgO-MnS complex inclusions in steel were changed obviously with the addition of Al. When containing 0.001 wt.% Al, they consisted of a central single MgO particle and outside, the MnS phase. When containing 0.020 wt.% Al, they comprised several small MgO particles entrapped by the MnS phase. Because the former could nucleate intragranular acicular ferrites (IAFs) and the latter was non-nucleant, the main intragranular microstructures in HAZs were ductile IAFs and brittle ferrite side plates (FSPs), respectively. Therefore, HAZ toughness of the steel plate without Al addition after high-heat-input welding of 400 kJ/cm was significantly better than that of the steel plate with Al addition. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
The Effect of Concentrate/Iron Ore Ratio Change on Agglomerate Phase Composition
Metals 2018, 8(11), 973; https://doi.org/10.3390/met8110973
Received: 17 October 2018 / Revised: 16 November 2018 / Accepted: 19 November 2018 / Published: 21 November 2018
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Abstract
The work is focused on studying the influence of the ratio of concentrate to iron ore on the phase composition of the iron ore agglomerate. The concentrate has significantly higher iron content than used iron ore, and is a determining factor, which influences [...] Read more.
The work is focused on studying the influence of the ratio of concentrate to iron ore on the phase composition of the iron ore agglomerate. The concentrate has significantly higher iron content than used iron ore, and is a determining factor, which influences the richness of the batch and consequently, the richness of the agglomerate. The increased iron content in the agglomerate can be achieved by adjusting the raw material ratio in which iron ore materials are added to the agglomeration mixture. If the ratio is in favor of iron ore this reflects in lower iron content in the resulting agglomeration mixture. If the ratio is in favor of a concentrate, which is finer, the fraction share of less than 0.5 mm will be increased, the permeability of the batch will be reduced, the performance of the sintering belt will decrease and the presence of solid pollutants will increase. The possibility of concentrate replacement by iron-rich iron ore with granulometry similar to that of concentrate was experimentally verified. The effect of the concentrate replacement by the finer iron-rich ore was tested in a laboratory sintering pan. There were performed six sinterings, with gradually changing ratio concentrate/iron ore (C/O). The change in the ratio of concentrate to iron ore, does not cause the occurrence of new phases, only the change in their prevalence, which does not bring a significant change of the qualitative indicators of the compared agglomerates. Concentrate replacement by iron ore up to 50% was optimal from technological, quality, and environmental aspects. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Improvement of Heat-Affected Zone Toughness of Steel Plates for High Heat Input Welding by Inclusion Control with Ca Deoxidation
Metals 2018, 8(11), 946; https://doi.org/10.3390/met8110946
Received: 22 October 2018 / Revised: 13 November 2018 / Accepted: 13 November 2018 / Published: 14 November 2018
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Abstract
The characteristics of inclusions and microstructure in heat-affected zones (HAZs) of steel plates with Ca deoxidation after high heat input welding of 400 kJ·cm−1 were investigated through simulated welding experiments and inclusions automatic analyzer systems. Typical inclusions in HAZs of steels containing [...] Read more.
The characteristics of inclusions and microstructure in heat-affected zones (HAZs) of steel plates with Ca deoxidation after high heat input welding of 400 kJ·cm−1 were investigated through simulated welding experiments and inclusions automatic analyzer systems. Typical inclusions in HAZs of steels containing 11 ppm and 27 ppm Ca were recognized as complex inclusions with the size in the range of 1~3 μm. They consisted of central Al2O3 and peripheral CaS + MnS with TiN distributing at the edge (Al2O3 + CaS + MnS + TiN). With increasing Ca content in steel, the average size of inclusions decreased from 2.23 to 1.46 μm, and the number density increased steadily from 33.7 to 45.0 mm−2. Al2O3 + CaS + MnS + TiN complex inclusions were potent to induce the formation of intragranular acicular ferrite (IAF). Therefore, the HAZ toughness of steel plates after high heat input welding was improved significantly by utilizing oxide metallurgy technology with Ca deoxidation. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Damage Mechanism of Copper Staves in a 3200 m3 Blast Furnace
Metals 2018, 8(11), 943; https://doi.org/10.3390/met8110943
Received: 24 October 2018 / Revised: 7 November 2018 / Accepted: 8 November 2018 / Published: 13 November 2018
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Abstract
Copper staves have been widely applied in large blast furnaces especially those whose inner volumes exceed 2000 m3 due to high cooling capacity. In the past decade, copper staves suffered severe damages in some blast furnaces, which not only shortened their campaign [...] Read more.
Copper staves have been widely applied in large blast furnaces especially those whose inner volumes exceed 2000 m3 due to high cooling capacity. In the past decade, copper staves suffered severe damages in some blast furnaces, which not only shortened their campaign lives, but also caused huge economic losses. In order to make out this phenomenon, the damage mechanism of copper staves was investigated via analyzing the chemical composition, thermal conductivity, metallographic aspects and microstructure in this paper. As a result, the working state was more likely to damage copper staves instead of their materials. At the beginning, the poor quality of the coke and the large bosh angle promoted the development of edge airflow, which intensified the erosion of refractory materials, resulting in the fall-off of slag crusts and damage of cooling water pipes. After repair, the cooling capacity of copper staves still declined, causing the temperature to rise easily; consequently, hydrogen attack happened when the temperature reached 370 °C, which degraded the performance of copper staves. Therefore, copper staves were worn too quickly to form slag crusts, which finally failed under the hydrogen attack and the scouring of the edge airflow at high temperatures. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Crystallization Behaviors of Anosovite and Silicate Crystals in High CaO and MgO Titanium Slag
Metals 2018, 8(10), 754; https://doi.org/10.3390/met8100754
Received: 31 August 2018 / Revised: 12 September 2018 / Accepted: 21 September 2018 / Published: 24 September 2018
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Abstract
Electric-furnace smelting has become the dominant process for the production of the titanium slag from ilmenite in China. The crystallization behaviors of anosovite and silicate crystals in the high CaO and MgO titanium slag were studied to insure smooth operation of the smelting [...] Read more.
Electric-furnace smelting has become the dominant process for the production of the titanium slag from ilmenite in China. The crystallization behaviors of anosovite and silicate crystals in the high CaO and MgO titanium slag were studied to insure smooth operation of the smelting process and the efficient separation of titanium slag and metallic iron. The crystallization behaviors were studied by a mathematical model established in this work. Results show that the crystallization order of anosovite and silicate crystals in high CaO and MgO titanium slag during cooling is: Al2TiO5 > Ti3O5 > MgTi2O5 > MgSiO3 > CaSiO3 > FeTi2O5 > Mn2SiO4 > Fe2SiO4. Al2TiO5 and Ti3O5 have higher crystallization priority and should be responsible for the sharp increase in viscosity of titanium slag during cooling. The total crystallization rates of anosovite and silicate crystals are mainly controlled by Al2TiO5 and MgSiO3, respectively. The mass ratio of Ti2O3/ΣTiO2 has a prominent influence on the total crystallization rate of anosovite crystals while the mass ratio of MgO/FeO has a slight influence on the total crystallization rate of anosovite crystals. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Prediction Model of Iron Ore Pellet Ambient Strength and Sensitivity Analysis on the Influence Factors
Metals 2018, 8(8), 593; https://doi.org/10.3390/met8080593
Received: 2 July 2018 / Revised: 23 July 2018 / Accepted: 25 July 2018 / Published: 30 July 2018
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Abstract
The Ambient Compressive Strength (CS) of pellets, influenced by several factors, is regarded as a criterion to assess pellets during metallurgical processes. A prediction model based on Artificial Neural Network (ANN) was proposed in order to provide a reliable and economic control strategy [...] Read more.
The Ambient Compressive Strength (CS) of pellets, influenced by several factors, is regarded as a criterion to assess pellets during metallurgical processes. A prediction model based on Artificial Neural Network (ANN) was proposed in order to provide a reliable and economic control strategy for CS in pellet production and to forecast and control pellet CS. The dimensionality of 19 influence factors of CS was considered and reduced by Principal Component Analysis (PCA). The PCA variables were then used as the input variables for the Back Propagation (BP) neural network, which was upgraded by Genetic Algorithm (GA), with CS as the output variable. After training and testing with production data, the PCA-GA-BP neural network was established. Additionally, the sensitivity analysis of input variables was calculated to obtain a detailed influence on pellet CS. It has been found that prediction accuracy of the PCA-GA-BP network mentioned here is 96.4%, indicating that the ANN network is effective to predict CS in the pelletizing process. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Phosphorus-Containing Mineral Evolution and Thermodynamics of Phosphorus Vaporization during Carbothermal Reduction of High-Phosphorus Iron Ore
Metals 2018, 8(6), 451; https://doi.org/10.3390/met8060451
Received: 29 May 2018 / Revised: 11 June 2018 / Accepted: 11 June 2018 / Published: 13 June 2018
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Abstract
High-phosphorus iron ore is not used because of its high phosphorus content. Phosphorus is mainly present in fluorapatite. In this work, the phosphorus vaporization that occurs during the carbothermal reduction of fluorapatite was investigated. The thermodynamic principle of vaporization, which removes phosphorus during [...] Read more.
High-phosphorus iron ore is not used because of its high phosphorus content. Phosphorus is mainly present in fluorapatite. In this work, the phosphorus vaporization that occurs during the carbothermal reduction of fluorapatite was investigated. The thermodynamic principle of vaporization, which removes phosphorus during carbothermal reduction, was elucidated, and the mineral evolution of high-phosphorus iron ore was summarized. The results demonstrate that it was difficult to reduce fluorapatite when only carbon was added. When Al2O3, SiO2, and Fe2O3 were added, the dephosphorization of fluorapatite was stimulated, and the dephosphorization temperature decreased. A phosphorus-containing gas was generated during this process. SiO2 had the strongest effect on the dephosphorization of fluorapatite. The carbothermal reduction rate of fluorapatite accelerated when SiO2, Al2O3, and Fe2O3 were concurrently added. These oxides were advantageous for vaporization dephosphorization. The gas-phase volatiles were detected through gas-phase mass spectrometry. The volatiles were primarily P2 or PO. The temperature range of 1000–1100 °C was the optimum for vaporization dephosphorization. This article provides a theoretical and experimental basis for the development and utilization of high-phosphorus iron ore through vaporization dephosphorization. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Research on the Bonding Interface of High Speed Steel/Ductile Cast Iron Composite Roll Manufactured by an Improved Electroslag Cladding Method
Metals 2018, 8(6), 390; https://doi.org/10.3390/met8060390
Received: 17 April 2018 / Revised: 25 May 2018 / Accepted: 25 May 2018 / Published: 28 May 2018
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Abstract
In the present study, a new electroslag cladding method by using of the advanced current supplying mold technology was used for manufacturing the high speed steel (HSS)/ductile cast iron (DCI) composite roll. The graphite morphology, matrix microstructure, elements distribution, carbides morphology, and carbides [...] Read more.
In the present study, a new electroslag cladding method by using of the advanced current supplying mold technology was used for manufacturing the high speed steel (HSS)/ductile cast iron (DCI) composite roll. The graphite morphology, matrix microstructure, elements distribution, carbides morphology, and carbides composition have been investigated by means of optical microscope (OM), scanning electron microscope (SEM), and energy dispersive spectroscopy (EDS). With increasing distance from the HSS side, a transition of graphite morphology from naught to existence and from small and dispersed to large and nonuniform was obtained at the interface. It was closely related to the fact that graphite in DCI participated in the phase change and the roll core surface and its nearby positions was heated to a high temperature by the liquid slag during the whole electroslag cladding process. Due to the combined effects of melting and elements diffusion, a significant migration of the alloying elements have occurred through the line scan analysis. Based on this, different types of carbides with the morphology and composition were found at the bonding interface. In addition, no obvious slag inclusions, porosity, shrinkage and other defects at the bonding interface were found. Results of the tensile test also illustrated that the bonding interface had a good quality and it could fully meet the requirements of the roll. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
Modeling and Experimental Study of Ore-Carbon Briquette Reduction under CO–CO2 Atmosphere
Metals 2018, 8(4), 205; https://doi.org/10.3390/met8040205
Received: 26 February 2018 / Revised: 14 March 2018 / Accepted: 21 March 2018 / Published: 23 March 2018
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Abstract
Iron ore-carbon briquette is often used as the feed material in the production of sponge iron via coal-based direct reduction processes. In this article, an experimental and simulation study on the reduction behavior of a briquette that is made by hematite and devolatilized [...] Read more.
Iron ore-carbon briquette is often used as the feed material in the production of sponge iron via coal-based direct reduction processes. In this article, an experimental and simulation study on the reduction behavior of a briquette that is made by hematite and devolatilized biochar fines under CO–CO2 atmosphere was carried out. The reaction model was validated against the corresponding experimental measurements and observations. Modeling predictions and experimental results indicated that the CO–CO2 atmosphere significantly influences the final reduction degree of the briquette. Increasing the reduction temperature did not increase the final reduction degree but was shown to increase the carbon that was consumed by the oxidative atmosphere. The influence of the CO–CO2 atmosphere on the briquette reduction behavior was found to be insignificant in the early stage but became considerable in the later stage; near the time of the briquette reaching its maximum reduction degree, both iron oxide reduction and metallic iron re-oxidation were able to occur. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessArticle
In Situ Spectroscopic Analysis of the Carbothermal Reduction Process of Iron Oxides during Microwave Irradiation
Metals 2018, 8(1), 49; https://doi.org/10.3390/met8010049
Received: 25 December 2017 / Revised: 9 January 2018 / Accepted: 9 January 2018 / Published: 11 January 2018
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Abstract
The effects of microwave plasma induction and reduction on the promotion of the carbothermal reduction of iron oxides (α-Fe2O3, γ-Fe2O3, and Fe3O4) are investigated using in situ emission spectroscopy measurements during [...] Read more.
The effects of microwave plasma induction and reduction on the promotion of the carbothermal reduction of iron oxides (α-Fe2O3, γ-Fe2O3, and Fe3O4) are investigated using in situ emission spectroscopy measurements during 2.45 GHz microwave processing, and the plasma discharge (such as CN and N2) is measured during microwave E-field irradiation. It is shown that CN gas or excited CN molecules contribute to the iron oxide reduction reactions, as well as to the thermal reduction. On the other hand, no plasma is generated during microwave H-field irradiation, resulting in thermal reduction. Magnetite strongly interacts with the microwave H-field, and the reduction reaction is clearly promoted by microwave H-field irradiation, as well as thermal reduction reaction. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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Open AccessReview
CO2 Utilization in the Ironmaking and Steelmaking Process
Metals 2019, 9(3), 273; https://doi.org/10.3390/met9030273
Received: 11 December 2018 / Revised: 17 February 2019 / Accepted: 18 February 2019 / Published: 28 February 2019
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Abstract
Study on the resource utilization of CO2 is important for the reduction of CO2 emissions to cope with global warming and bring a beneficial metallurgical effect. In this paper, research on CO2 utilization in the sintering, blast furnace, converter, secondary [...] Read more.
Study on the resource utilization of CO2 is important for the reduction of CO2 emissions to cope with global warming and bring a beneficial metallurgical effect. In this paper, research on CO2 utilization in the sintering, blast furnace, converter, secondary refining, continuous casting, and smelting processes of stainless steel in recent years in China is carried out. Based on the foreign and domestic research and application status, the feasibility and metallurgical effects of CO2 utilization in the ferrous metallurgy process are analyzed. New techniques are shown, such as (1) flue gas circulating sintering, (2) blowing CO2 through a blast furnace tuyere and using CO2 as a pulverized coal carrier gas, (3) top and bottom blowing of CO2 in the converter, (4) ladle furnace and electric arc furnace bottom blowing of CO2, (5) CO2 as a continuous casting shielding gas, (6) CO2 for stainless steel smelting, and (7) CO2 circulation combustion. The prospects of CO2 application in the ferrous metallurgy process are widespread, and the quantity of CO2 utilization is expected to be more than 100 kg per ton of steel, although the large-scale industrial utilization of CO2 emissions is just beginning. It will facilitate the progress of metallurgical technology effectively and promote the energy conservation of the metallurgical industry strongly. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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