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A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Sustainable Processes".

Deadline for manuscript submissions: closed (25 November 2023) | Viewed by 14026

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Special Issue Editors

Dr. Xin Yao

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Guest Editor

School of Metallurgy and Energy, North China University of Science and Technology, Tangshan 063210, China
Interests: CO₂ resource utilization; low-carbon smelting; high-nitrogen steel; metallurgical slag; waste heat recovery; energy conversion and clean utilization; electric furnace steelmaking
Special Issues, Collections and Topics in MDPI journals

Dr. Huaqing Xie

E-Mail Website
Guest Editor

School of Metallurgy, Northeastern University, Shenyang 110819, China
Interests: hydrogen smelting; CO₂ resource utilization; energy conversion and clean utilization; hydrogen-rich blast furnace injection; hydrogen base shaft furnace direct reduction; electric furnace steelmaking
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

With the development of the metallurgical industry, enormous challenges in energy and environment have come forth. Switching traditional industry into green metallurgical industry is of great value. The production process in traditional metallurgical industry uses large amounts of fossil fuels, which consume energy and emit CO₂ intensively. The industry is in urgent need of advanced techniques for replacing fossil fuels with renewable energy, and decreasing energy consumption and CO₂ emission. Renewable energy contains biomass energy, wind energy, solar energy, etc. Replacing fossil fuels with renewable energy is the trend in future energy utilization in the metallurgical industry. Furthermore, about 70% of the energy in the metallurgy process is discharged via slag, blast furnace gas, converter gas, etc. The efficient disposition of slag, blast furnace gas, and converter gas has played a critical role in emission reduction in the metallurgy industry. Additionally, advanced technology steers the upgrading of green metallurgical industry. Replacing fossil fuels with renewable energy, energy recovery, and advanced technology lead to the development of green metallurgical industry.

Recent advances in renewable energy, energy recovery, and advanced technology in the metallurgy industry have gained great attention, including the topics of the utilization of renewable energy replacing fossil fuels, resource utilization of metallurgical slag, low-carbon smelting technology in the steel industry, smelting mechanism and control process of non-modulated high-strength steel for automobiles, etc. This Special Issue targets researchers and technologists interested in all aspects of the science, technology, and applications of renewable energy and green metallurgy technology. It will feature original research papers and reviews about renewable energy replacing fossil fuels, energy recovery, and advanced technology of the metallurgy industry. We invite scientists working in the area of renewable energy and green metallurgy technology to contribute to this Special Issue.

This Special Issue on “Renewable energy and Green Metallurgy Technology” aims to curate novel advances to reduce fossil fuel consumption and CO₂ emission in the metallurgical industry. Topics include, but are not limited to:

Biomass energy and solar energy replacing fossil fuels;
Resource utilization of metallurgical slag;
Low-carbon smelting technology in steel;
CO₂ resource utilization;
Strengthening mechanisms and smelting processes of non-quenched and tempered steel for automobiles;
High-nitrogen steel smelting technology;

Dr. Xin Yao
Dr. Huaqing Xie
Guest Editors

Manuscript Submission Information

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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. Processes 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 2400 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

renewable energy
metallurgical slag
energy conversion and clean utilization
hydrogen energy
CO₂ resource utilization
low-carbon smelting
non-quenched and tempered steel
high-nitrogen steel

Published Papers (14 papers)

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Editorial

Jump to: Research

6 pages, 165 KiB

Open AccessEditorial

Renewable Energy and Green Metallurgy Technology

by Xin Yao and Huaqing Xie

Processes 2024, 12(2), 340; https://doi.org/10.3390/pr12020340 - 5 Feb 2024

Cited by 1 | Viewed by 778

Abstract

Iron and steel are regarded as the foundation for national development, but their processing consumes huge amounts of fossil fuel and produces large amounts of carbon dioxide gas, which is not conducive to the sustainable development of society [...] Full article

(This article belongs to the Special Issue Renewable Energy and Green Metallurgy Technology)

Research

Jump to: Editorial

17 pages, 4350 KiB

Open AccessArticle

Numerical Simulation of Mold Slag Entrapment Behavior in Nonoriented Silicon Steel Production Process

by Wenjie Huo, Caijun Zhang, Yanchao Zhang and Xuekai Li

Processes 2024, 12(1), 167; https://doi.org/10.3390/pr12010167 - 10 Jan 2024

Viewed by 647

Abstract

This paper is based on the surface defects of casting billets in the production process of nonoriented silicon steel plates at a steel plant in North China. Taking the parameters of a slab mold in the nonoriented silicon steel production process as a prototype, the flow field characteristics of the mold under the same section, different drawing speed and immersion depth were systematically studied by using a LES (large eddy simulation) and VOF (volume of fluid) coupling algorithm. The results show that under the current conditions, when the critical slag entrapment speed increases from 1.0 m/min to 1.2 m/min, the nozzle insertion depth increases linearly with the critical slag entrapment speed, while when the nozzle insertion depth exceeds 130 mm, the increasing effect of further increasing the nozzle insertion depth on the critical slag entrapment speed begins to decrease. When the drawing speed of continuous casting is kept constant at 1.4 m/min, the abnormal fluctuation height of the steel slag interface is significantly improved when the angle of the water nozzle is increased from 15° to 20°, and the proportion of slag entrapment is also reduced from 0.376% to 0.015%. When the nozzle angle is 25°, the slag entrapment ratio is reduced to 0%, and the steel slag interface also ensures a certain activity. The numerical simulation results were applied to the industrial site, and the slag inclusion rate and crack rate of the billet in the continuous casting process of nonoriented silicon steel were obviously improved after the optimization process. Full article

(This article belongs to the Special Issue Renewable Energy and Green Metallurgy Technology)

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15 pages, 6915 KiB

Open AccessArticle

Numerical Simulation of Heat Transfer of Roller Slag in Centrifugal Preparation of Inorganic Fiber

by Chunyu Liu, Weixing Wang, Xiwei Qi, Baoxiang Wang, Wei Chen, Kai Zhao, Jie Zhen and Qiaorong Zhang

Processes 2023, 11(11), 3225; https://doi.org/10.3390/pr11113225 - 14 Nov 2023

Viewed by 831

Abstract

The synergistic preparation of aluminum silicate ceramic fibers from dust removal ash and fly ash is a newly developed process that achieves green and high added value treatment of solid waste. In this process, the centrifugal fiber forming method is used to treat molten slag to obtain aluminum silicate ceramic fibers. During the production process, the centrifugal roller, as a key component in fiber forming, is in long-term contact with high-temperature slag. The heat transfer between the two causes a huge temperature gradient inside the roller material, causing significant thermal stress inside the material, which has a significant impact on the stability of the centrifugal roller structure and its working condition. This article mainly conducts numerical simulation research on the heat transfer between the roller and the slag during the centrifugal fiber forming process, providing theoretical support for ensuring the structural stability of the roller and improving its service life. The research was carried out using the FLUENT module of the ANSYS software (V2021R1), and the heat transfer model of the slag and roller was established. The effects of the internal circulating water, different slag temperatures, different slag film widths, and different boundary layer thicknesses on the heat transfer of the roller were analyzed. The results show that the water temperature at the outlet is about 6 °C higher than that at the inlet on average; when the temperature of the slag increases by 1 °C, the temperature of the roller surface in contact with the slag increases by 0.91 °C; when the width of the slag on the roll surface is 11–17 mm and the slag thickness (boundary layer thickness) is less than 1 mm, it is beneficial for fiber production. Full article

(This article belongs to the Special Issue Renewable Energy and Green Metallurgy Technology)

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16 pages, 9713 KiB

Open AccessArticle

Diffusion Behavior of Carbon and Silicon in the Process of Preparing Silicon Steel Using Solid-State Decarburization

by Li Wen, Liqun Ai, Lukuo Hong, Yuqing Zhou, Guangpeng Zhu and Caijiao Sun

Processes 2023, 11(11), 3176; https://doi.org/10.3390/pr11113176 - 7 Nov 2023

Cited by 1 | Viewed by 934

Abstract

In this study, we investigated the relationship between the decarburization effect of the solid-state decarburization method for preparing silicon steel and the atomic diffusion behavior in the matrix, focusing on 1 mm thick Fe-0.18 wt% C-Si (1.5, 3.5 wt%) alloy strips as the research object. Solid-state decarburization experiments were carried out in an Ar-H₂O-H₂ atmosphere, and the self-diffusion behavior of C and Si in Fe-C-Si alloy system was simulated by molecular dynamics. The results show that the molecular dynamics simulation results are consistent with the decarburization experimental results. When the temperature is lower than 800 °C, the atoms maintain a compact bcc structure, so the migration rate of carbon is low. When the temperature rises, the atoms move violently, resulting in the destruction of the crystal structure. Because the atomic arrangement tends towards a disordered structure, the migration rate of C is high and the diffusion coefficient increases. The experimental results showed that the decarburization rate was accelerated. At the same temperature, the diffusion activation energy Q = 48.7 kJ·mol⁻¹ of carbon in an Fe-3.5 wt% Si-C alloy matrix can be calculated. The diffusion activation energy of carbon Q = 47.3 kJ·mol⁻¹ was calculated using a molecular dynamics simulation. When the content of Si is 3.5 wt% and 1.5 wt%, the diffusion series of Si can be expressed as D_{3.5Si, Si} = 8.54 × 10⁻¹⁰ exp(−33,089.7/RT) m²/s and D_{1.5Si, Si} = 2.06 × 10⁻⁹ exp(−46,641.5/RT) m²/s, respectively. When the Si content is 3.5 wt%, the diffusion coefficient of Si is larger. After diffusion to the near surface, it combines with the remaining O to form a continuous strip of SiO₂. When the Si content is 1.5 wt%, the diffusion coefficient of Si is small. The remaining O diffuses in the matrix and will oxidize when encountering Si; it cannot aggregate in a highly-dispersed distribution. The lattice transition from face centered cubic lattice austenite to body centered cubic lattice ferrite occurred in the matrix of the thin strip. The diffusion coefficient of C in ferrite is much larger than that in austenite. Therefore, the decarburization rate suddenly increases before decarburization stagnation. With the increase in Si content, the diffusion activation energy of C decreases, which promotes the decarburization effect. Full article

(This article belongs to the Special Issue Renewable Energy and Green Metallurgy Technology)

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12 pages, 3874 KiB

Open AccessArticle

Study on Mushy Zone Coefficient in Solidification Heat Transfer Mathematical Model of Thin Slab with High Casting Speed

by Zhijun Ding, Yuekai Xue, Limin Zhang, Chenxiao Li, Shuhuan Wang and Guolong Ni

Processes 2023, 11(11), 3108; https://doi.org/10.3390/pr11113108 - 30 Oct 2023

Cited by 1 | Viewed by 791

Abstract

When the casting speed of the thin slab continuous caster is increased, the ratios of the solid and liquid phases in the solidification front of the molten steel in the mold change, which affects the thickness of the solidified shell. In order to accurately calculate the thickness of the solidified shell and determine the value range of the mushy zone coefficient suitable for the mathematical model of solidification heat transfer at high casting speed, this paper established the solidification heat transfer mathematical model in thin slab funnel mold, and the influence of different mushy zone coefficients on the accuracy of solidification heat transfer mathematical model was analyzed and compared with the actual solidified shell thickness. The results showed that, when the casting speed was increased to 4~6 m/min and the coefficient of the mush zone coefficient was 3 × 10⁸~9 × 10⁸ kg/(m³⋅s), the thickness of solidified shell calculated by the solidification heat transfer model was in good agreement with that measured in practice. The research in this paper provides an important reference for the establishment of the solidification heat transfer mathematical model at high casting speed in the future. Full article

(This article belongs to the Special Issue Renewable Energy and Green Metallurgy Technology)

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15 pages, 1721 KiB

Open AccessArticle

The Kinetic Mechanism of the Thermal Decomposition Reaction of Small Particles of Limestone at Steelmaking Temperatures

by Chenxiao Li, Yun Zhang, Yuekai Xue, Kaixuan Zhang, Shuhuan Wang, Huakang Sun and Huaqing Xie

Processes 2023, 11(9), 2712; https://doi.org/10.3390/pr11092712 - 11 Sep 2023

Cited by 1 | Viewed by 1235

Abstract

Converter blowing limestone powder making slag steelmaking process has the advantages of low carbon and high efficiency, and can realize the resource utilization of CO₂ in the metallurgical process, which is in line with the development direction of green metallurgy. Based on a thermogravimetric-differential thermal analyzer, the kinetic mechanism of decomposition of small limestone at steelmaking temperatures was investigated by a modified double extrapolation method. The results showed that with a higher rate of heating, limestone decomposition lagged, and decomposition temperature increased. Furthermore, the smaller the limestone particle size, the lower the activation energy of decomposition. Compared with N₂, air, and O₂, small limestone powder used for converter blowing could complete more rapid decomposition, and the time required for decomposition shortened by about 1/3, although the decomposition temperature increased in the CO₂. The limestone decomposition rate increased and then decreased at low to high CO₂ partial pressures. With a limiting link, the inhibition was more significant under high CO₂ partial pressure, but the reaction can be fully completed by 1000 °C. The decomposition type modeled was stochastic nucleation and subsequent growth. As the partial pressure of CO₂ increased from 25% to 100%, the number of reaction stages, n, increased. Full article

(This article belongs to the Special Issue Renewable Energy and Green Metallurgy Technology)

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16 pages, 8721 KiB

Open AccessArticle

Promoting Effect of Microwave Field on Gas Phase Diffusion Limited Magnetite Reduction in Carbon Monoxide

by Meijie Zhou, Liqun Ai, Lukuo Hong, Caijiao Sun and Shuai Tong

Processes 2023, 11(9), 2709; https://doi.org/10.3390/pr11092709 - 11 Sep 2023

Viewed by 728

Abstract

To investigate the effect of microwave irradiation on the rate of magnetite reduction while increasing the gas phase diffusion rate limit, the microstructure and kinetics of CO reduction of magnetite powder were studied. The investigation was conducted through microwave irradiation and conventional heating at 900~1100 °C. Under the two heating methods, the iron crystal is selectively reduced and gradually expanded along the direction normal to the length of the ore powder, forming a strip of iron crystal that penetrates the powder and expands outward across the width. The microwave field can effectively improve the sintering of minerals. The changes in Avrami exponents m and k in the reduction process were determined by combining the Johnson–Mehl–Avrami (JMA) model with the lnln method. The microwave field did not change the limiting step. Microwave irradiation proves to be the most effective means to enhance both the initial reduction rate and the rate during the primary iron crystal precipitation phase. The morphology of the iron crystal takes on a dense punctate shape, influenced by the rate of diffusion control. Full article

(This article belongs to the Special Issue Renewable Energy and Green Metallurgy Technology)

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12 pages, 5198 KiB

Open AccessArticle

Study on Efficient Removal Method of Fine Particulate Dust in Green Metallurgy Process

by Haiying Li, Hairui Xue, Junya Zhang and Guijie Zhang

Processes 2023, 11(9), 2573; https://doi.org/10.3390/pr11092573 - 28 Aug 2023

Cited by 1 | Viewed by 804

Abstract

In order to solve the problem of the low removal efficiency of fine particles in the flue gases of the metallurgy process, a chemical agglomeration pretreatment method was studied. The coagulant solution of xanthan gum, konjac gum, and their mixtures was selected to research the reunion effects of and the efficiency of gravitational dust removal of fine dust in the gas of the converter flue using a self-built experimental platform. Moreover, the effects of wetting agent type, dust concentration, pressure, and flue gas velocity on the fine grain removal efficiency were investigated. The results showed that the mixed solution of 1 g/L mixed gum and 0.5 g/L SDS had the most obvious effect on the particle size increasing of fine dust particles and the best removal effect when the flue gas velocity was 10 m/s. There was a peak particle size of 85.32 μm increased about eight times larger, and the removal efficiencies reached 51.46% for PM₂.₅ and 53.13% for PM₁₀. The Box–Behnken experimental design combined with a response surface analysis method was used to optimize the parameters of the mixed gum concentration, pressure, and flue gas velocity. The optimal removal conditions were 1 g/L, 0.4 MPa, and 10 m/s. The results of this study can provide efficient methods and technical support for pre-processing and efficient removal of fine particles in heavy-polluting industries such as steel making. This will promote the green development of the metallurgical industry. Full article

(This article belongs to the Special Issue Renewable Energy and Green Metallurgy Technology)

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17 pages, 23938 KiB

Open AccessArticle

Research on Metallurgical Saw Blade Surface Defect Detection Algorithm Based on SC-YOLOv5

by Lili Meng, Xi Cui, Ran Liu, Zhi Zheng, Hongli Shao, Jinxiang Liu, Yao Peng and Lei Zheng

Processes 2023, 11(9), 2564; https://doi.org/10.3390/pr11092564 - 27 Aug 2023

Viewed by 922

Abstract

Under the background of intelligent manufacturing, in order to solve the complex problems of manual detection of metallurgical saw blade defects in enterprises, such as real-time detection, false detection, and the detection model being too large to deploy, a study on a metallurgical saw blade surface defect detection algorithm based on SC-YOLOv5 is proposed. Firstly, the SC network is built by integrating coordinate attention (CA) into the Shufflenet-V2 network, and the backbone network of YOLOv5 is replaced by the SC network to improve detection accuracy. Then, the SIOU loss function is used in the YOLOv5 prediction layer to solve the angle problem between the prediction frame and the real frame. Finally, in order to ensure both accuracy and speed, lightweight convolution (GSConv) is used to replace the ordinary convolution module. The experimental results show that the [email protected] of the improved YOLOv5 model is 88.5%, and the parameter is 31.1M. Compared with the original YOLOv5 model, the calculation amount is reduced by 56.36%, and the map value is increased by 0.021. In addition, the overall performance of the improved SC-YOLOv5 model is better than that of the SSD and YOLOv3 target detection models. This method not only ensures the high detection rate of the model, but also significantly reduces the complexity of the model and the amount of parameter calculation. It meets the needs of deploying mobile terminals and provides an effective reference direction for applications in enterprises. Full article

(This article belongs to the Special Issue Renewable Energy and Green Metallurgy Technology)

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13 pages, 2403 KiB

Open AccessArticle

Dynamic Characteristics Analysis of Metallurgical Waste Heat Radiative Drying of Thin Layers of Sewage Sludge

by Hongyan Guo, Zhiwei Tan, Haiying Li, Yue Long, Aimin Ji and Liangxu Liu

Processes 2023, 11(9), 2535; https://doi.org/10.3390/pr11092535 - 24 Aug 2023

Cited by 1 | Viewed by 806

Abstract

The utilization of metallurgical waste heat for urban sludge drying and dewatering not only affects the subsequent cost of sludge treatment but also provides a pathway for the rational utilization of metallurgical waste heat. The influence of different experimental conditions on sludge drying characteristics, such as drying temperature and thickness, was analyzed based on metallurgical waste heat. Based on the analysis and evaluation of the drying kinetics parameters of commonly used drying mathematical models, a modified Midilli drying kinetic model is proposed. The kinetic parameters and effective diffusivity of sludge drying were analyzed in three stages of sludge drying: rising rate, constant rate, and falling rate. By utilizing the Arrhenius equation, the relationship between the effective diffusion coefficient and thermodynamic temperature is established, revealing the apparent activation energies for the three stages of urban sludge drying as 29.772 kJ·mol⁻¹, 37.129 kJ·mol⁻¹, and 39.202 kJ·mol⁻¹, respectively. This is closely related to the migration, diffusion, and mass transfer resistance of sludge moisture, indicating that the thickness of sludge accumulation affects the drying time of sludge during the treatment of municipal sludge. Full article

(This article belongs to the Special Issue Renewable Energy and Green Metallurgy Technology)

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14 pages, 4726 KiB

Open AccessArticle

Thermodynamic Analysis of Hydrogen Production from Bio-Oil Steam Reforming Utilizing Waste Heat of Steel Slag

by Zhijun Ding, Yang Liu, Xin Yao, Yuekai Xue, Chenxiao Li, Zhihui Li, Shuhuan Wang and Jianwei Wu

Processes 2023, 11(8), 2342; https://doi.org/10.3390/pr11082342 - 3 Aug 2023

Cited by 1 | Viewed by 735

Abstract

(1) Background: The discharged temperature of steel slag is up to 1450 °C, representing heat having a high calorific value. (2) Motivation: A novel technology, integrating bio-oil steam reforming with waste heat recovery from steel slag for hydrogen production, is proposed, and it is demonstrated to be an outstanding method via thermodynamic calculation. (3) Methods: The equilibrium productions of bio-oil steam reforming in steel slag under different temperatures and S/C ratios (the mole ratio of steam to carbon) are obtained by the method of minimizing the Gibbs free energy using HSC 6.0. (4) Conclusions: The hydrogen yield increases first and then decreases with the increasing temperature, but it increases with the increasing S/C. Considering equilibrium calculation and actual application, the optimal temperature and S/C are 706 °C and 6, respectively. The hydrogen yield and hydrogen component are 109.13 mol/kg and 70.21%, respectively, and the carbon yield is only 0.08 mol/kg under optimal conditions. Compared with CaO in steel slag, iron oxides have less effect on hydrogen production from bio-oil steam reforming in steel slag. The higher the basicity of steel slag, the higher the obtained hydrogen yield and hydrogen component of bio-oil steam reforming in steel slag. It is demonstrated that appropriately decreasing iron oxides and increasing basicity could promote the hydrogen yield and hydrogen component of bio-oil steam reforming that utilizes steel slag as a heat carrier during the industrial application. Full article

(This article belongs to the Special Issue Renewable Energy and Green Metallurgy Technology)

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22 pages, 5092 KiB

Open AccessArticle

A Comprehensive Model for Evaluating Titanium Industry Security in China

by Xiangwei Hui, Ming Qi, Wenhao Wang, Sen Yang and Chengqi Zhang

Processes 2023, 11(8), 2286; https://doi.org/10.3390/pr11082286 - 30 Jul 2023

Viewed by 1049

Abstract

Currently, China is the largest consumer of titanium (Ti), yet the development of its Ti industry is limited by numerous factors, such as industrial structure imbalance. This study aimed to evaluate the security of China’s Ti industry from 2010 to 2020, seeking to identify relevant issues and propose policy strategies. Firstly, a comprehensive evaluation system for Ti industry security was established, encompassing aspects of availability, economics, and sustainability. Secondly, the entropy weight technique for order preference by similarity to an ideal solution (TOPSIS) combination method and gray correlation method were employed to assess the safety level of China’s Ti industry chain in each year from 2010 to 2020. Additionally, the coupling degree and sensitivity were used to analyze the dimension layers and index system to determine those that negatively impact the safety level of the Ti industry chain. The analysis results reveal that the economic level exerts a significant influence on the development of the Ti industry. Accordingly, under the same level of change, while considering availability, equal attention should be provided to economic considerations for a well-rounded evaluation of the industry’s safety level. Full article

(This article belongs to the Special Issue Renewable Energy and Green Metallurgy Technology)

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12 pages, 4240 KiB

Open AccessArticle

Behavior of Carbothermal Dephosphorization of Phosphorus-Containing Converter Slag and Its Resource Utilization

by Shuai Tong, Chenxiao Li, Liqun Ai, Shuhuan Wang and Shuai Zhang

Processes 2023, 11(7), 1943; https://doi.org/10.3390/pr11071943 - 27 Jun 2023

Viewed by 881

Abstract

Phosphorus-containing converter slag is a common waste in the iron and steel industry, and has the characteristics of high generation and low secondary-utilization values; however, the high-phosphorus content in converter slag limits its ability to be recycled during the steelmaking process. In this study, the dephosphorization behavior of converter slag by carbothermal reduction was studied through experiments and thermodynamic calculations. The results showed that the gas product of the converter slag produced by carbothermal reduction was mainly P₂, and that part of P₂ entered the iron phase to generate iron phosphate compounds. With the increase in Fe content, the amount of P₂ also increased, which may provide a suitable new direction for the production of ferrophosphorus. Based on the carbothermal reduction theory, a new “circulating steelmaking process of converter steel slag gasification” was proposed and applied to Chengde Iron and Steel Group Co., Ltd. (Chengde, China). The industrial production practice showed that the process did not affect the dephosphorization effect of the next furnace, and that the average iron, steel, and slagging-material consumption per furnace was reduced by 4.74 kg and 608 kg, respectively. CO₂ emissions were reduced by 4.86 kg, thus achieving the goals of energy saving, environmental protection, and efficient dephosphorization. Full article

(This article belongs to the Special Issue Renewable Energy and Green Metallurgy Technology)

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14 pages, 4434 KiB

Open AccessArticle

Effect of Powder Formulation and Energy Density on the Nitrogen Content, Microstructure, and Mechanical Properties of SLMed High-Nitrogen Steel

by Xin Sun, Jianbiao Ren, Shuhuan Wang and Dingguo Zhao

Processes 2023, 11(7), 1937; https://doi.org/10.3390/pr11071937 - 27 Jun 2023

Cited by 2 | Viewed by 890

Abstract

The effects of powder formulation, including elemental mixed powder (EMP) and alloy mixed powder (AMP), and energy density on the nitrogen content and microstructural characteristics of high-nitrogen steel prepared by selective laser melting were investigated. The results reveal that the samples prepared with EMP had more nonfusion flaws and a relatively low density, with a maximum of only 92.36%, while samples prepared with AMP had fewer defects and a relative density of up to 97.21%. The nitrogen content and microstructural characteristics were significantly influenced by the laser energy density. The relative density of the EMP samples increased from 88.29% to 92.36% as the laser energy density increased from 83.3 J/mm³ to 125 J/mm³, while the relative density of the AMP samples rose from 93.31% to 97.21%, and the number of defects and the nitrogen content decreased. The mechanical properties of the AMP samples were superior to those of the EMP samples when the energy density rose, and the strength of the high-nitrogen steel first rose and then fell. The AMP samples showed the best mechanical properties when the energy density was 104.2 J/mm³, which corresponds to a laser power of 250 W, a scanning speed of 1000 mm/s, and a layer thickness of 30 μm. The corresponding values of yield strength, ultimate tensile strength, and elongation were 958.8 MPa, 1189.2 MPa, and 30.66%, respectively. Full article

(This article belongs to the Special Issue Renewable Energy and Green Metallurgy Technology)

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