Electric Arc Research Articles

Stress-strain behavior of electric arc furnace slag concrete under uniaxial compression: Short- and long-term evaluation

This work analyzes the experimental behavior of electric arc furnace slag (EAFS) concretes in terms of full stress-strain behavior under uniaxial compression. Tests are carried out on samples cured for 28 days and for more than 6 years, representing both short- and long-term conditions. Results are discussed in terms of main mechanical strength (compressive and indirect tensile strength), deformative properties in the axial and transverse direction, i.e., secant modulus and Poisson’s coefficient, stress-strain relations during the load history, damage evolution and critical stress. Furthermore, two models for predicting the stress-strain behavior of concrete under repeated cycles are shown, for both natural aggregate concrete (NAC) and EAFS concrete. Results indicate that EAFS concrete has higher compressive and tensile strength than the reference, as well as better deformative properties. The aggregates type influences the deformability of the concrete also beyond the elastic regime, both in the longitudinal and transverse direction, with a different extent depending on the applied stress. Specifically, EAFS concrete attained higher secant modulus particularly at low-stress levels, while such improvement is less pronounced at high stresses. Instead, no significant differences were recorded concerning Poisson’s coefficient between NAC and EAFS concrete. The analytical models proposed hereafter well predict the experimental behavior for both concrete types.

Recycling Perspectives of Electric Arc Furnace Slag in the United States: A Review

This article presents a comprehensive review of electric arc furnace (EAF) slag recycling in the United States, examining its classification and the associated challenges and opportunities of its industrial use. The study affirms EAF slag's nonhazardous status. The main challenges identified in EAF slag applications include substantial variations in composition and volume instability during/after hydration. Analysis of the U.S. recycling practices reveals that EAF slag is predominantly reused, with minimal landfill disposal. However, its prevalent use as a low value‐added aggregate in construction applications underscores the industry's ongoing challenge to get additional value from EAF slag recycling. Despite these challenges, the study highlights a great potential for increased value extraction from EAF slag recycling. Beyond conventional applications as a clinker material for the cement industry, the review explores modern technologies for steelmaking slag recycling, revealing options for recovering valuable metals such as Cr, V, Mo, and Fe through methods such as leaching, reduction, and oxidation.

An Interpretable Time Series Forecasting Model for Predicting NOx Emission Concentration in Ferroalloy Electric Arc Furnace Plants

Considering the pivotal role of ferroalloys in the steel industry and the escalating global emphasis on sustainability (e.g., zero emissions and carbon neutrality), the demand for ferroalloys is anticipated to increase. However, the electric arc furnace (EAF) of ferroalloy plants generates substantial amounts of nitrogen oxides (NOx) because of the high-temperature combustion processes. Despite the substantial contributions of many studies on NOx prediction from various industrial facilities, there is a lack of studies considering the environmental condition of the EAF in ferroalloy plants. Therefore, this study presents a deep learning model for predicting NOx emissions from ferroalloy plants and further can provide guidelines for predicting NOx in industrial sites equipped with electric furnaces. In this study, we collected various historical data from the manufacturing execution system of electric furnaces and exhaust gas systems to develop a prediction model. Additionally, an interpretable artificial intelligence method was employed to track the effects of each variable on the NOx emissions. The proposed prediction model can provide decision support to reduce NOx emissions. Furthermore, the interpretation of the model contributes to a better understanding of the factors influencing NOx emissions and the development of effective strategies for emission reduction in ferroalloys EAF plants.

Исследование изменения геометрических параметров образцов, наплавленных методом GMAW при воздействии на электрическую дугу продольного магнитного поля

Introduction. The paper presents the results of research of additive manufacturing process by electric arc with axial feeding of steel filler wire in protective gas environment (GMAW technology) with additional influence of external longitudinal magnetic field on electric arc. Purpose of work: an experimental study of the effect of a longitudinal magnetic field during additive manufacturing by an electric arc with axial feed of filler wire made of structural steels in a protective gas environment on the change in the geometrical characteristics of the layers being surfaced. Research Methods. The manufacturing of specimens was carried out on a 5-axis additive machine based on a CNC machine. Surfacing was carried out in the following modes: voltage 17.5 V; current 55–65 A; wire diameter 1.2 mm; wire material Sv-08G2S; wire feed rate 2,267 mm/min; approximate roll diameter 3.0 mm; roll length 50 mm; number of wires per one roll 312.5 mm; number of layers when surfacing the wall 5; magnet operation mode: alternating current with frequency 50 Hz, voltage 30 V; measured magnetic induction 5.7 mTl; initial height of the magnet above the substrate 10 mm; electrode stickout 10 mm; shielding gas: welding mixture CO2-Ar; gas pressure (flow rate) 0.15 MPa. Results and discussion. The conducted experimental study showed that the effect of longitudinal magnetic field had a statistically significant effect on the change in the dimensions of the singular, namely an increase in the width of the layers being surfaced by 34.1 %, with a calculated significance index close to zero, and a decrease in height by 20.2 %, with a calculated significance index equal to 2.7105. The effect of longitudinal magnetic field had a statistically significant effect on the change of the overall dimensions of the specimens consisting of five layers, namely, the width of the specimens increased by 11.2 % with a calculated significance index of 4.3103, and the height of the specimens decreased by 10.3 % with a calculated significance index of 6.3105. The effect of longitudinal magnetic field had no statistically significant effect on the change of the vertical deviation from straightness for the side walls of the specimens, with a calculated significance index of 0.3277, and had no statistically significant effect on the change of the error of the width of the walls of the specimens, with a significance index of 0.098.

Arc Quality Index Based on Three-Phase Cassie–Mayr Electric Arc Model of Electric Arc Furnace

In steel recycling, the optimization of Electric Arc Furnaces (EAFs) is of central importance in order to increase efficiency and reduce costs. This study focuses on the optimization of electric arcs, which make a significant contribution to the energy consumption of EAFs. A three-phase equivalent circuit integrated with the Cassie–Mayr arc model is used to capture the nonlinear and dynamic characteristics of arcs, including arc breakage and ignition process. A particle swarm optimization technique is applied to real EAF data containing current and voltage measurements to estimate the parameters of the Cassie–Mayr model. Based on the Cassie–Mayr arc parameters, a novel Arc Quality Index (AQI) is introduced in the study, which can be used to evaluate arc quality based on deviations from optimal conditions. The AQI provides a qualitative assessment of arc quality, analogous to indices such as arc coverage and arc stability. The study concludes that the AQI serves as an effective operational tool for EAF operators to optimize production and increase the efficiency and sustainability of steel production. The results underline the importance of understanding electric arc dynamics for the development of EAF technology.

Use of steel slag to improve the mechanical properties of subgrades in clayey soils

Large quantities of steel slag are generated annually throughout the world. Some slag from steel manufacturing is reused in the generation of other materials, such as hot mix asphalt aggregate, pipe filling, concrete, among others. The research aims to enrich the mechanical characteristics of soils and minimize road construction costs. The objective of this research is to find a material that increases the mechanical properties of the subgrade in clay soils with different plasticity indices using Electric Arc Furnace Slag (EAF) in percentages: 5%, 15% and 25% of the weight of the soil. From the tests carried out on the soil samples using parameters, it was possible to classify them by the Unified Soil Classification System (USCS) and also by the American Association of Highway Transportation (AASHTO) as low and high clays. plasticity. When testing the samples in their natural state and the samples with EAF, results were obtained that showed an improvement in the physical and mechanical properties of the clay soils with the addition of EAF, increasing the values of the Bearing Capacity Ratio (CBR) and the maximum dry density. of the clay soil as the percentage of HAE in the mixture increased. The optimal HAE addition content corresponds to 25% of the weight of the soil.

Blending electric arc furnace slag and municipal incineration bottom ash to make ceramic tiles

Blending electric arc furnace slag and municipal incineration bottom ash to make ceramic tiles

Waste to Resource: Surface Modification of Electric Arc Furnace Flue Dust by Ball Milling and In Situ Carbonization

AbstractIn this article, instead of synthesizing the electrode active material using expensive precursors that lead to high carbon emissions to the atmosphere during fabrication, an alternative engineering approach is presented for the utilization of the electric arc furnace flue dust, which is an industrial waste, as anode material in lithium-ion batteries. In this scope, firstly ball milling of the flue dust with citric acid is applied and then in situ carbonization conditions are optimized by pyrolyzing the mixture at different temperatures (600 °C and 750 °C) and times (4 h and 6 h). Every sample delivers capacities greater than graphite. Structural, morphological, and chemical characterization results demonstrate that the designed method not only promotes the formation of a nanometer-thick carbon layer formation over the particles but also induces partial phase transformation in the structure. The best performance is achieved when citric acid is used as the carbon source and the ball-milled powder is treated at 600 °C for 4 h in nitrogen (C6004): It delivers 714 mAh g−1 capacity under a current load of 50 mA g−1 after 100 cycles. This research is expected to set an example for the utilization of different industrial wastes in high value-added applications, such as energy storage. Graphical Abstract

Low-Cost System with Transient Reduction for Automatic Power Factor Controller in Three-Phase Low-Voltage Installations

In power engineering, the importance of maintaining a high power factor in low-voltage electrical installations is known. In power substations for industry, the usual method of coupling is to use an automatic power factor controller which connects capacitors banks (with electromagnetic contactors). Sometimes, AC reactors are connected to the phases of the capacitors banks (to reduce transient phenomena and the deforming regime), depending on the desired value of the power factor. This paper presents an analysis (more focused on experimentation) of a low-cost system for automatic regulation of the power factor with a reduction in transients and an increase in the life of contactors (eliminating the electric arc during switching on), with capacitors banks for low-voltage three-phase installations that connect the capacitors banks by means of one three-phase solid-state relay (an expensive device for a quality device; one is used for all capacitors banks) and using several electromagnetic contactors. The automatic power factor adjustment system has a controller with a microprocessor with six outputs, controlled by the phase shift between the current (measured with a current transformer proportional to the current in a bar) and the phase voltage, which is part of a system of distribution bars (L1,2,3, N) from which electrical consumers (e.g., induction motors) are supplied. To reduce transients when connecting capacitors banks, a three-phase solid-state relay and two related electromagnetic contactors are used for each capacitors bank. The automatic power factor controller is connected to two low-capacity PLCs that control the logic of connecting the capacitors banks to reduce transients. By using the proposed regulation system, a cheaper control solution is obtained compared to the use of one solid-state relay for each capacitors banks, under the conditions in which the power factor adjustment is made as in the classic solution. If twelve capacitors banks are used, the proposed installation is 22.57% cheaper than the classical power factor regulation installation.

Metallurgical, mechanical, and corrosion behavior of AISI 304L joints welded using variable arc energy inputs and subjected to thermal aging

The effect of three levels of welding arc energy input on the metallurgical, mechanical, and corrosion behavior of AISI 304L stainless steel was studied with the aim of investigating and recommending the most useful range of process parameters for improved performance of engineering structures made from this industrially important alloy. The gas tungsten arc welding process was employed, and all the joints were butt-welded using a single-V groove design. With an increase in heat input, the δ-ferrite phase changed from lathy to vermicular, besides the heat-affected zones of all the welds exhibiting grain coarsening effects. Postweld thermal aging led to the preferential occurrence of carbides in the interdendritic regions, which degraded their corrosion performance. Thermal aging did not affect the tensile strength of these welds, but their ductility was significantly impacted. The extent of segregation of Cr and C, especially, was observed to be the least in the case of low heat input welds. This study establishes that while designing welding procedures for AISI 304L structures, low welding arc energy should be used as it promotes better mechanical as well as corrosion properties.

One-step synthesis of TiO2/Fe3O4/C hydrophilic magnetic nanocomposites using the magnetized submerged arc discharge method

This study investigates the production of TiO2/Fe3O4/C hydrophilic magnetic nanocomposites produced via a one-step novel method using the submerged arc discharge method applied in liquid media of ethanol and ethanol–ammonia under the influence of external magnetic field. The magnetized submerged arc discharge forms a longer-lasting plasma arc, thereby affecting the growth of spherical and tubular carbon nanocomposites. More reactive species enrolled in the carbon growth in the magnetized submerged arc discharge, resulting in the ordered crystalline structure. The nanocomposites synthesized in ethanol–ammonia show hydrophilic characteristics, indicated by their dispersion improvement in the water and the presence of the vibrations of hydroxyl, amine, and –CN functional groups in Fourier transfer infrared (FTIR) spectra. The preparation technique described in this study using magnetized submerged arc discharge is supposed to be a simple and less costly preparation method that can potentially be further applied to produce numerous other nanocomposites.

Influence of initial electric arc root position on electric arc behavior with spark plugs in large lean burn spark ignited gas engines

Increasing efficiency while reducing emissions leads to high mean effective pressures, high compression ratios and increasingly lean operation for spark ignited large gas engines. Despite these boundary conditions, gas engines must be operated between knocking and misfiring at low cycle-to-cycle fluctuations. The excess air ratio and the ignition process of the lean mixture greatly influence the stability of the combustion process. To enable sufficiently low cycle-to-cycle fluctuation of the combustion process despite the ever increasing excess air ratio levels, it is necessary to understand and investigate the sub-areas of the engine process, for example, ignition, flow condition and mixture formation. This paper focuses on one sub-area of conventional spark ignition, the influence of the electric arc root position on the origin and stretching of the electric arc, because electric arc behavior is considered important in the subsequent combustion process. The results show that electric arc roots on the downstream end of the electrodes tend to enable a longer electric arc length at the first electric arc short circuit (i.e. the first abrupt shortening of the electric arc during its spark duration) than electric arcs with electric arc roots on the upstream ends of the electrodes.

Tackling Uncertainty: Forecasting the Energy Consumption and Demand of an Electric Arc Furnace with Limited Knowledge on Process Parameters

The iron and steel industry significantly contributes to global energy use and greenhouse gas emissions. The rising deployment of volatile renewables and the resultant need for flexibility, coupled with specific challenges in electric steelmaking (e.g., operation optimization, optimized power purchasing, effective grid capacity monitoring), require accurate energy consumption and demand forecasts for electric steel mills to align with the energy transition. This study investigates diverse approaches to forecast the energy consumption and demand of an electric arc furnace—one of the largest consumers on the grid—considering various forecast horizons and objectives with limited knowledge on process parameters. The results are evaluated for accuracy, robustness, and costs. Two grid connection capacity monitoring approaches—a one-step and a multi-step Long Short-Term Memory neural network—are assessed for intra-hour energy demand forecasts. The one-step approach effectively models energy demand, while the multi-step approach encounters challenges in representing different operational phases of the furnace. By employing a combined statistic–stochastic model integrating a Seasonal Auto-Regressive Moving Average model and Markov chains, the study extends the forecast horizon for optimized day-ahead electricity procurement. However, the accuracy decreases as the forecast horizon lengthens. Nevertheless, the day-ahead forecast provides substantial benefits, including reduced energy balancing needs and potential cost savings.

Numerical Simulation of the Hydrogen-Based Directly Reduced Iron Melting Process

In the context of carbon reduction and emission reduction, the new process of electric arc furnace (EAF) steelmaking based on direct hydrogen reduction is an important potential method for the green and sustainable development of the steel industry. Within an electric furnace for the hydrogen-based direct reduction of iron, after hydrogen-based directly reduced iron (HDRI) is produced through a shaft furnace, HDRI is melted or smelted in an EAF to form final products such as high-purity iron or high-end special steel. As smelting proceeds in the electric furnace, it is easy for pieces of HDRI to bond to each other and become larger pieces; they may even form an “iceberg”, and this phenomenon may then worsen the smelting working conditions. Therefore, the melting of HDRI is the key to affecting the smelting cycle and energy consumption of EAFs. In this study, based on the basic characteristics of HDRI, we established an HDRI melting model using COMSOL Multiphysics 6.0 and studied the HDRI melting process, utilizing pellets with a radius of 8 mm. The results of our simulation show that the HDRI melting process can be divided into three different stages: generating a solidified steel layer, melting the solidified steel layer, and melting HDRI bodies. Moreover, multiple HDRI processes are prone to bonding in the melting process. Increasing the spacing between pieces of HDRI and increasing the preheating temperature used on the HDRI can effectively reduce the aforementioned bonding phenomenon. When the melting pool temperature is 1873 K, increasing the spacing of HDRI to 10 mm and increasing the initial HDRI temperature to 973 K was shown to effectively reduce or eliminate the bonding phenomenon among pieces of HDRI. In addition, with the increase in the melting pool temperature, the time required for melting within the three stages of the HDRI melting process shortened, and the melting speed was accelerated. With the increase in the temperature used to preheat the HDRI, the duration of the solidified steel layer’s existence was also shortened, but this had no significant impact on the time required for the complete melting of HDRI. This study provides a theoretical basis for the optimization of the HDRI process within EAFs.

Measurement of medium-voltage AC air arc temperature and particle number density based on dual-wavelength Moiré deflection technology

AC air arcs are generated in medium-voltage (MV) power systems under the effect of harsh weather conditions, equipment aging, and high penetration of distributed generation, threatening equipment and public safety. The arc current and temperature are low due to the wide application of arc suppression devices. In this scenario, the MV AC air arc does not satisfy the local thermodynamic equilibrium (LTE) condition. In addition, the repeated arcing and extinguishing processes further complicate the arc discharge mechanism, which bring challenges in the modeling and detection of MV AC air arcs. Experimental methods are a direct and efficient approach to determine the properties of arc plasmas. In this study, a dual-wavelength Moiré deflection diagnostic system was established to determine the time evolution of the particle density and radial distribution of the temperature in an MV AC air arc without relying on the LTE assumption. The electron number density and heavy particle number density change transiently during the arc discharge process and change gradient along the radial direction. The heavy particle temperature and electron temperature were then calculated based on the measured particle number density. During the arcing stage, the temperature of the electrons exceeded that of the heavy particles significantly, and the arc deviated from LTE. Finally, the limitations of the traditional single-wavelength Moiré deflection method are analyzed. The classic single-wavelength Moiré deflection method, while capable of estimating heavy particle temperature in plasma, exhibits a significant error in electron density estimation compared to the dual-wavelength Moiré deflection method.

Development of Fire Resistant Composite Material Using Fire Retardant Filler for Electrical Application

Safety is paramount across diverse sectors, with a growing emphasis on dependability. Preventing fires in electrical contexts and employing fire-resistant techniques using additives have become crucial. This involves the development of composite materials, typically incorporating substances like Alumina Rehydrate (ATH), metal hydroxides, or specialized additives such as epoxies, polyester, or polyurethane resins within polymer matrices. These formulations include fire-retardant fillers, underscoring their significance in enhancing safety and reliability. Increasing the fire resistance of the composite can be achieved through various methods such as delaying ignition, reducing flame spread, mitigating smoke emissions when exposed to high temperatures, and employing fire-resistant compounds to quench potential electrical arcs, especially in electrical applications where combustible materials pose significant hazards. These items consist of electrical casings, wire pathways, insulation, and other crucial components for ensuring fire safety within various systems. These components are chosen based on their electrical characteristics, strength, and the necessity for fire resistance, all of which contribute to achieving a harmonious balance. Careful consideration is given to adhesive matrices during the selection and optimization process as part of the development procedure. Advanced manufacturing methods such as Compression Melding, Resin Transfer Melding, or filament winding are utilized to produce composite components with standardized properties, enhancing overall efficiency.

Finite element method for sustainable and resilient structures made with bar and fiber -reinforced EAFS concrete

Structural engineers have to address the climate change challenge by designing sustainable and resilient structures. At this juncture, Electric Arc Furnace Slags (EAFS), a steel-industry waste, are used in replacement of natural aggregates to enhance concrete properties. Moreover, steel and synthetic fibers are added to improve the postcracking behavior while the traditional bar reinforcement enhances the tensile performance. This makes EAFS concrete substantially ductile compared to normal concrete, which contributes to a higher structural resiliency, and hence minimizes functionality disruptions. However the use of fiber and bar -reinforced EAFS concrete in structures is still limited due to the uncertainties introduced by EAFS and fibers. This justify the development of advanced modeling techniques (ie. Finite element Analysis, FEA), which can be used to predict the behavior of EAFS concrete structures at the designing stage. This work build up from the extensive work of the coauthors in the testing of EAFS concrete and, more recently, in the developed FEA of fiber-reinforced EAFS concrete. In this paper the modeling of bar reinforcement is added to the FEA to study the behavior of structural elements made with fiber-reinforced EAFS concrete. The presented FEA is validated through full-scale experiments (four-point flexural test), which shows that the presented FEA is appropriate. The presented numerical model enables to study phenomena difficult to study from experiments or in-situ such as the cracking. It is worth noting that the addition of steel fibers reduced the crack mouth opening displacement in 29.3% and the depth of the cracks in 12.7% in the presented EAFS concrete.

Comparative Technical and Economic Analyses of Hydrogen-Based Steel and Power Sectors

Decarbonizing the current steel and power sectors through the development of the hydrogen direct-reduction iron ore–electric arc furnace route and the 100% hydrogen-fired gas turbine cycle is crucial. The current study focuses on three clusters of research works. The first cluster covers the investigation of the mass and energy balance of the route and the subsequent application of these values in experiments to optimize the reduction yield of iron ore. In the second cluster, the existing gas turbine unit was selected for the complete replacement of natural gas with hydrogen and for finding the most optimal mass and energy balance in the cycle through an Aspen HYSYS model. In addition, the chemical kinetics in the hydrogen combustion process were simulated using Ansys Chemkin Pro to research the emissions. In the last cluster, a comparative economic analysis was conducted to identify the levelized cost of production of the route and the levelized cost of electricity of the cycle. The findings in the economic analysis provided good insight into the details of the capital and operational expenditures of each industrial sector in understanding the impact of each kg of hydrogen consumed in the plants. These findings provide a good basis for future research on reducing the cost of hydrogen-based steel and power sectors. Moreover, the outcomes of this study can also assist ongoing, large-scale hydrogen and ammonia projects in Uzbekistan in terms of designing novel hydrogen-based industries with cost-effective solutions.

The Influence of Voltage on Gliding Arc Discharge Characteristics, the Composition of Air Plasma, and the Properties of BG-11 Medium

A gliding arc discharge (GAD) plasma device has been developed and tested. Possible applications areas for GAD plasma could be microalgae suspension treatments and the creation of plasma-activated water. To understand its behavior, the influence of the input power on the electrical characteristics of the generated GAD plasma was investigated using an oscilloscope. The waveforms of the voltage and current of GAD plasma are presented. The duration of the discharge time and the evolution of the arc during discharge were determined and investigated. It was revealed that the increase in the output voltage prolonged the duration of the arc discharge. The composition of the air plasma was investigated using a flame-emission spectrometer and acousto-optic emission spectrometer. It was revealed that the main species in the emission spectra of the GAD air plasma were N2, N2+, N+, NO, and O species. Furthermore, the increase in the input power enhanced the ionization degree of the air plasma and increased the intensities of the emission lines associated with N2+, NO, and O species. An increase in the conductivity of the BG-11 medium was observed. Physicochemical analyses of the plasma-activated BG-11 medium indicated an increase in the concentration of nitrite and nitrate ions and hydrogen peroxide with an enhancement of the voltage.

Potent biological activity of newly fabricated silver nanoparticles coated by a carbon shell synthesized by electrical arc

Highly effective AgNPs@C was efficiently synthesized by electrical arc powered by single spark unit which was sufficient to ionize the dielectric media (deionized water) through applying strong electric field between the electrodes (silver and carbon). The AgNPs@C shell was characterized in terms of stability, morphology and phase structure. All characterizations showed that the prepared silver nanoparticles were spherical with average size reached 17 nm coated with carbon shell. The antibacterial effect of the synthesized nanoparticles was tested against Pseudomonas aeruginosa in comparison to Ceftazidime (commonly used antibiotic against P. aeruginosa infections). It was revealed that AgNPs@C shell has superior activity with inhibition zone diameter reached 15 mm and minimum inhibitory concentration reached 2 µg/mL. The observed activity was further confirmed by confocal microscope which showed an increased red region, representing the dead cells, correlated with the presence of AgNPs@C. Moreover, transmission electron microscope studies implied the possible AgNPs@C antibacterial mechanism of action was the nanoparticles adherence to the bacterial membrane causing cell lysis. The molecular studies against fimH (virulence adhesion gene), rmpA (mucoid factor encoding gene), and mrkA (biofilm forming gene) proved the inhibition of their genetic expression. The cytotoxic effect of the synthesized AgNPs@C showed CC50 reached 235.5 μg/mL against normal lung cells (L929 cell line).