Metals

Research

13 pages, 4355 KiB

Open AccessArticle

Effects of Al₂O₃/TiO₂/Na₂O on Lime Dissolution in Steelmaking Slag

by Kan Yu, Yanling Zhang, Shuai Zhang and Ming Gao

Metals 2023, 13(2), 209; https://doi.org/10.3390/met13020209 - 20 Jan 2023

Cited by 1 | Viewed by 1082

The mechanism of lime dissolution in steelmaking slag and the factors that influence the dissolution rate are highly significant in improving the efficiency of the steelmaking process; however, they are yet to be fully understood. Here, the effects of Al₂O₃ [...] Read more.

The mechanism of lime dissolution in steelmaking slag and the factors that influence the dissolution rate are highly significant in improving the efficiency of the steelmaking process; however, they are yet to be fully understood. Here, the effects of Al₂O₃/TiO₂/Na₂O additives on the dissolution rate of lime and the composition of molten slag were investigated using a rotating cylinder technique. The results indicate that the promotion coefficients at 1400 °C decrease in the order of Na₂O > TiO₂ > Al₂O₃. Furthermore, the CaO dissolution rate and kinetic parameters were calculated, and the lime dissolution mechanisms in the presence or absence of Al₂O₃, TiO₂, and Na₂O were compared. Additionally, the data show that ATN (a mixture with a mass ratio of Al₂O₃:TiO₂:Na₂O = 15:4:3) can be used as a suitable flux in the steelmaking process. Full article

(This article belongs to the Special Issue Thermodynamics and Kinetics in Metallurgical Processes)

► Show Figures

Figure 1

13 pages, 2687 KiB

Open AccessArticle

Analysis on Ancient Bloomery Ironmaking Technology: The Earliest Ironmaking Evidence in the Central Plains of China Was Taken as the Research Object

by Shuoyang Li, Yanxiang Li, Rong Zhu and Hongyang Wang

Metals 2022, 12(8), 1307; https://doi.org/10.3390/met12081307 - 3 Aug 2022

Cited by 3 | Viewed by 2404

Abstract

The slag found in Hengdong Jiangxian County, Shanxi Province has been recognized by archaeologists as the earliest evidence of bloomery ironmaking in China. The slag was characterized and analyzed by chemical titration, inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray diffraction (XRD), scanning [...] Read more.

The slag found in Hengdong Jiangxian County, Shanxi Province has been recognized by archaeologists as the earliest evidence of bloomery ironmaking in China. The slag was characterized and analyzed by chemical titration, inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive spectrometer (SEM-EDS), and tescan integrated mineral analysis (TIMA). The smelting technology in ancient China was explored, combined with thermodynamic theory. The results of chemical titration shown that the total Fe was as high as 64.18%, which means that it was very difficult to produce iron on a large scale with the ancient bloomery ironmaking technology, consuming a lot of iron ore while producing very little iron. The distribution of FeO was relatively dispersed, while that of Fe₂O₃ particles was concentrated and large. The source of Fe₂O₃ in the slag can be roughly identified as the oxidized metallic iron, which could not be separated in the slag in the past. Tescan integrated mineral analysis (TIMA) images show that Fayalite and Wustite are the main phase forms in smelting slag. The existence of fayalite proves that the temperature of a slag system should reach the condition of liquid phase formation during the smelting process. Based on the characterization results, the metallurgical conditions of the slag at that time are inferred by FactSage7.1. The theoretical smelting temperature was between 1150 °C and 1200 °C. The fayalite and aluminosilicate in the slag had obvious displacement and inhomogeneity, which pointed to the forging temperature ranging from 1050 °C to 1100 °C. Full article

(This article belongs to the Special Issue Thermodynamics and Kinetics in Metallurgical Processes)

► Show Figures

Figure 1

16 pages, 2771 KiB

Open AccessArticle

Investigation of the Reaction Kinetics of a Sinter-Reduction Process in the Thermal Reserve Zone of a Blast Furnace Using a Modified Sectioning Method

by Li Zhu, Wenlong Zhan, Yubo Su, Yi Liu and Keng Wu

Metals 2022, 12(8), 1259; https://doi.org/10.3390/met12081259 - 26 Jul 2022

Viewed by 1251

Abstract

With the development of large-scale and high-performing blast furnaces, it is necessary to extensively study the reaction characteristics and related kinetic parameters of sinters in their heat reserve area. Under reducing atmosphere conditions, the reduction of iron oxide in sinter is closely related [...] Read more.

With the development of large-scale and high-performing blast furnaces, it is necessary to extensively study the reaction characteristics and related kinetic parameters of sinters in their heat reserve area. Under reducing atmosphere conditions, the reduction of iron oxide in sinter is closely related to the gasification reaction of coke. Based on a simulation experiment, the transition point from chemical reactions to diffusion and the related kinetic parameters were determined through a sectioning method. The results showed that increasing the proportion of low-grade coke increased the chemical-reaction rate, but it slightly decreased the mass-transfer and diffusion rates. An increase in the coke particle size increased the chemical-reaction, mass-transfer, and diffusion rates. However, an increase in the CO₂ volume fraction in gas reduced the chemical-reaction, diffusion, and mass-transfer rates. The mixing ratio of coke and sinters increased the chemical-reaction rate, but it decreased the mass-transfer and diffusion rates. The rate constant of the chemical reactions in the early stage was three orders of magnitude higher than that of the diffusion and mass-transfer coefficients, and the fitting degree was obviously better than that of the molecular diffusion in the later stage. Based on the thermodynamics of irreversible processes, the interference of the chemical reactions with the diffusion and mass transfer in the near-equilibrium region was tentatively established, the method of controlling coke diffusion and mass transfer in the later reaction stage was given and related kinetic parameters were corrected, and further improvement of the modified sectioning method was completed. Full article

(This article belongs to the Special Issue Thermodynamics and Kinetics in Metallurgical Processes)

► Show Figures

Figure 1

13 pages, 4292 KiB

Open AccessArticle

Study of Thermodynamic for Low-Reactive CaO-BaO-Al₂O₃-SiO₂-CaF₂-Li₂O Mold Flux Based on the Model of Ion and Molecular Coexistence Theory

by Maoguo Zhao, Gang Li, Zhirong Li, Qiangqiang Wang and Shengping He

Metals 2022, 12(7), 1099; https://doi.org/10.3390/met12071099 - 27 Jun 2022

Cited by 2 | Viewed by 1329

Abstract

A thermodynamic model was proposed to calculate the activity of components in low-reactive CaO-BaO-Al₂O₃-SiO₂-CaF₂-Li₂O mold flux, which was chosen to improve the castability of high Al steel, based on the ion and molecular [...] Read more.

A thermodynamic model was proposed to calculate the activity of components in low-reactive CaO-BaO-Al₂O₃-SiO₂-CaF₂-Li₂O mold flux, which was chosen to improve the castability of high Al steel, based on the ion and molecular coexistence theory. The model was indirectly validated, and the effects of the mass ratio of Al₂O₃/SiO₂, contents of CaF₂ and Li₂O on the reactivity of components were discussed. The results reveal that the reactivity of mold flux attenuated with the increase in the mass ratio of Al₂O₃/SiO₂. The decrease in reactivity was insignificant as the mass ratio was over 3.5. The steel–slag reaction experiment confirmed that the reactivity of mold flux is weakened when the content of SiO₂ below 8 wt%. The reactivity of mold flux increased nearly linearly with the increase in CaF₂ content, indicating that the proportion of CaF₂ should be kept to a minimum in the flux. In addition, the compositional regions involving around 6 wt% Li₂O should be avoided to develop low-reactive mold flux. Full article

(This article belongs to the Special Issue Thermodynamics and Kinetics in Metallurgical Processes)

► Show Figures

Graphical abstract

9 pages, 2176 KiB

Open AccessArticle

Titanium Removal from Metallurgical-Grade Silicon Melts Using High-Basicity Index Slag and Carbon Dioxide Injection

by Xiao Long, Wenbo Luo, Jun Lv, Falou Chen, Xiang Li and Shaolei Long

Metals 2022, 12(6), 1004; https://doi.org/10.3390/met12061004 - 11 Jun 2022

Cited by 1 | Viewed by 2973

Abstract

In this study, novel slags with a high basicity index were used to refine silicon melts with carbon dioxide injection to effectively remove Ti from metallurgical-grade silicon. Different compositions of the initial slag were used, and silicon samples were obtained during the refining. [...] Read more.

In this study, novel slags with a high basicity index were used to refine silicon melts with carbon dioxide injection to effectively remove Ti from metallurgical-grade silicon. Different compositions of the initial slag were used, and silicon samples were obtained during the refining. The results indicate that the Ti-removal rate initially increased with an increase in the basicity index, and it decreased after the basicity index exceeded 1.4. During the refining, silicon emulsification was observed at the slag–silicon interface, which was restricted by the increased basicity index of slags. Impurities that were concentrated in silicon droplets near the slag–silicon interfaces were oxidized, wetted by slags, and transferred to the slag phase. After 15 min of refining, up to 59 wt% of Ti in silicon could be removed and the Ti-concentrating phase in the slag contained 2.05 wt% of Ti. The results of this study provide a reference for low-cost Ti removal from metallurgical-grade silicon using a refining method. Full article

(This article belongs to the Special Issue Thermodynamics and Kinetics in Metallurgical Processes)

► Show Figures

Figure 1

10 pages, 7452 KiB

Open AccessArticle

Equilibrium Phase Relations for a SiO₂-Al₂O₃-FeO_x System at 1300 °C and 1400 °C in Air

by Song Li, Yuchao Qiu, Junjie Shi, Jianzhong Li and Changsheng Liu

Metals 2022, 12(6), 926; https://doi.org/10.3390/met12060926 - 27 May 2022

Cited by 2 | Viewed by 1847

Abstract

A long-term fundamental study for the construction of the thermodynamic database of a metallurgical slag system has been proposed. In the present work, the equilibrium phase relations for the key ternary SiO₂-Al₂O₃-FeO_x system at 1300 °C [...] Read more.

A long-term fundamental study for the construction of the thermodynamic database of a metallurgical slag system has been proposed. In the present work, the equilibrium phase relations for the key ternary SiO₂-Al₂O₃-FeO_x system at 1300 °C and 1400 °C in air were experimentally determined by the equilibrium-quenching technique, followed by X-ray Photoelectron Spectroscopy and Scanning Electron Microscope equipped with an Energy Dispersive X-ray Spectrometer analysis. The oxidation states of Fe₂O₃ and Fe₃O₄ were confirmed at 1300 °C and 1400 °C, respectively, from both XPS detection and FactSage calculation. Within the high-SiO₂ composition range, the solid phases of silica, mullite, magnetite and ferric oxide were confirmed as the equilibrium phases. Based on the equilibrium compositions, the 1300 °C and 1400 °C isotherms were projected onto a SiO₂-Al₂O₃-FeO_x quasi-ternary phase diagram; however, obvious discrepancies with about a 20 °C difference were confirmed from further comparison with the predictions given by FactSage, indicating that more efforts are needed for the updating of the current thermodynamic database relating to metallurgical slag oxide systems. Full article

(This article belongs to the Special Issue Thermodynamics and Kinetics in Metallurgical Processes)

► Show Figures

Figure 1

14 pages, 34850 KiB

Open AccessArticle

A Study of the Crystallization Properties of CaO-SiO₂-Al₂O₃ Glass Phase in Sinter

by Rui-Feng Xin and Xing-Min Guo

Metals 2022, 12(6), 915; https://doi.org/10.3390/met12060915 - 26 May 2022

Cited by 1 | Viewed by 1565

Abstract

The glass phase is one of the binding phases in high-basicity sinter, which is mainly formed during a high-temperature cooling process while cannot crystallize in time. The phase still involves the “structure” information of the binding phase’s liquid phase in the sinter. In [...] Read more.

The glass phase is one of the binding phases in high-basicity sinter, which is mainly formed during a high-temperature cooling process while cannot crystallize in time. The phase still involves the “structure” information of the binding phase’s liquid phase in the sinter. In addition, the generation of glassy phases can seriously deteriorate the metallurgical properties of sintered ore. However, the formation mechanism and crystallization process of glass phases are still unclear. In this work, the glass phase and the crystallized samples of the CaO-SiO₂-Al₂O₃ system were characterized using X-ray diffraction, optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy and Raman spectroscopy. The effect of alkalinity (R) and Al₂O₃ on crystallization and the relationship between crystallization and structure are discussed. The results showed that the chemical composition significantly influences the crystallization of the CaO-SiO₂-Al₂O₃ glass. Decreasing basicity (R = 0.8–1.2, the mass ratio of CaO and SiO₂) favors the crystallization of the glass phase, while increasing the content of Al₂O₃ (9–12%) can inhibit the crystallization of the glass phase. In addition, the crystallization order of the 45mass%CaO-45mass%SiO₂-10mass%Al₂O₃ sample is CaSiO₃ → CaAl₂O₄. Raman spectroscopic analysis showed that increase of slag basicity promoted the aggregation degree (Q₃/Q₂), resulting in deterioration of the glass phase crystallization. and that the glass phase crystallization deteriorated as the aggregation degree increased. However, increasing the Al₂O₃ content has little effect on the agglomeration degree but does promote the formation of SiO₄ tetrahedra (Q₀), which results in the deterioration of glass-phase crystallization. Full article

(This article belongs to the Special Issue Thermodynamics and Kinetics in Metallurgical Processes)

► Show Figures

Figure 1

11 pages, 3048 KiB

Open AccessArticle

Effect of Sulfur Content on Copper Recovery in the Reduction Smelting Process

by Long Wu, Hongyang Wang and Kai Dong

Metals 2022, 12(5), 857; https://doi.org/10.3390/met12050857 - 17 May 2022

Viewed by 2383

Abstract

This work discussed the advantages of reducing copper in molten copper slag with low S content. FactSage calculated the distribution of copper at equilibrium under different sulfur contents. The effect of sulfur content on copper recovery under different oxygen partial pressures in 1400 [...] Read more.

This work discussed the advantages of reducing copper in molten copper slag with low S content. FactSage calculated the distribution of copper at equilibrium under different sulfur contents. The effect of sulfur content on copper recovery under different oxygen partial pressures in 1400 °C was pointed out. The effect of sulfur content on copper recovery in the actual reduction process was explored through experimental research. Under the condition of low sulfur, the recovery ratio of copper and the stability of the experiment have an ideal result in fixed C/O in the experiment. Full article

(This article belongs to the Special Issue Thermodynamics and Kinetics in Metallurgical Processes)

► Show Figures

Figure 1

8 pages, 1115 KiB

Open AccessArticle

Dynamic Study on Vanadium Extraction Process in Basic Oxygen Furnance: Modeling Based on Gibbs’ Free Energy Minimization

by Zhenyu Zhou and Cong Luo

Metals 2022, 12(4), 612; https://doi.org/10.3390/met12040612 - 2 Apr 2022

Cited by 1 | Viewed by 1547

Abstract

Vanadium extraction process demands low residual vanadium and carbon loss, and variations of dissolved elements in hot metal must be determined to achieve it. A three parts dynamic model that applies the concept of Gibbs’ free energy minimization at the slag–metal interface is [...] Read more.

Vanadium extraction process demands low residual vanadium and carbon loss, and variations of dissolved elements in hot metal must be determined to achieve it. A three parts dynamic model that applies the concept of Gibbs’ free energy minimization at the slag–metal interface is proposed. Modeling simulation results shows good uniformity with plant experimental data, and the presented model can describe the vanadium extraction process in BOF qualitatively well. The effects of coolant addition and oxygen flow rate have been studied by modeling. The lack of coolant will reduce (FeO) content and elevate the molten bath temperature, which are harmful to deep vanadium removal with less carbon loss in semi-steel. The excessive oxygen flow rate has little effect on residual [V], and there is more carbon loss because of higher (FeO) content and molten bath temperature. Full article

(This article belongs to the Special Issue Thermodynamics and Kinetics in Metallurgical Processes)

► Show Figures

Figure 1

20 pages, 35662 KiB

Open AccessFeature PaperArticle

Numerical Investigation of Flow Characteristics of Molten Steel in the Tundish with Channel Induction Heating

by Bin Yang, Hong Lei, Yingshi Xu, Kun Liu and Peng Han

Metals 2021, 11(12), 1937; https://doi.org/10.3390/met11121937 - 30 Nov 2021

Cited by 6 | Viewed by 1611

Abstract

In the continuous process, fluid flow is an important physical phenomena in the tundish, as it affects the process of heat transfer, bubble motion and inclusion collision-coalescence and grow up. This paper undertakes a detailed numerical investigation of fluid flow characteristics in the [...] Read more.

In the continuous process, fluid flow is an important physical phenomena in the tundish, as it affects the process of heat transfer, bubble motion and inclusion collision-coalescence and grow up. This paper undertakes a detailed numerical investigation of fluid flow characteristics in the tundish with and without induction heating. The individual unit method and the volume subtraction model are applied to analyze the flow characteristics. A quantitative evaluation method of flow characteristics is proposed to investigate the flow characteristics. In the tundish with and without induction heating, firstly, the main flow behavior of molten steel is mixed flow in the receiving chamber; secondly, the main flow behavior of molten steel is plug flow in the channel; lastly, the main flow pattern is mixed flow, and the minor flow pattern is plug flow in the discharging chamber. The method of the volume subtraction model is an effective way to analyze the flow characteristics in the tundish with channel induction heating. Full article

(This article belongs to the Special Issue Thermodynamics and Kinetics in Metallurgical Processes)

► Show Figures

Figure 1

12 pages, 466 KiB

Open AccessFeature PaperArticle

New Analyzing Approaches for In Situ Interdiffusion Experiments to Determine Concentration-Dependent Diffusion Coefficients in Liquid Al–Au

by Toni Schiller, Elke Sondermann and Andreas Meyer

Metals 2021, 11(11), 1772; https://doi.org/10.3390/met11111772 - 4 Nov 2021

Cited by 5 | Viewed by 1776

Abstract

Interdiffusion coefficients are key parameters for the solidification process of liquid alloys. However, the determination of interdiffusion coefficients in liquid metals at high temperatures is a challenging and extensive task, due to a variety of potential systematic errors. In recent years we have [...] Read more.

Interdiffusion coefficients are key parameters for the solidification process of liquid alloys. However, the determination of interdiffusion coefficients in liquid metals at high temperatures is a challenging and extensive task, due to a variety of potential systematic errors. In recent years we have developed an X-ray in situ shear cell method for the measurement of interdiffusion coefficients in binary metallic melts. This technique enables the monitoring of the experiment in order to exclude fatal errors. Utilizing X-ray contrast, the method also provides a time-resolved concentration distribution. Such an in situ data set contains significantly more information than ex situ evaluated experiments. Available analyzing strategies do not fully exploit this potential yet. We present three new analyzing approaches that are able to retrieve a concentration-dependent interdiffusion coefficient from only one in situ data set. In that way, larger concentration differences become accessible for an experiment, which considerably decreases efforts. Using simulations, the approaches are checked for robustness. Furthermore, the approaches are run on real in situ data from a binary (0 to 9 at% Au-content) Al–Au alloy at 1000

^{°}

C which results in a concentration-dependent interdiffusion coefficient within the measured concentration range. Full article

(This article belongs to the Special Issue Thermodynamics and Kinetics in Metallurgical Processes)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Thermodynamics and Kinetics in Metallurgical Processes

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (11 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI