The present study aims at building a road map‐model for the steel melt compositional variations during the electric arc furnace (EAF) refining stage. The model is based on real measurements and ...compared to thermodynamic predictions. The studied parameters are steel melt carbon content and temperature. Herein, high‐temperature investigations (1550–1700 °C) with different chemistry ranges (mainly carbon content, 0.02–0.20% C) are carried out during the refining stage operation. The work develops a detailed empirical model to simulate the industrial EAF refining stage, which can be used to implement different optimization and control strategies for the EAF refining process. Furthermore, the study investigates the refining stage metallurgical phenomenon and the different operating conditions used to produce different steel grades over a wide range of carbon content; from ultra‐low carbon steel “0.02% C” till medium carbon steel grades “0.20% C.” Moreover, the work controls the steel melt tapping parameters for best cost achievement of steel melt yield and electrical energy consumption using simple measurements. These measurements are fitted into simple regression equations and contour plots for best refining stage control of the desired steel grade to be produced.
This work presents an empirical model, based on real‐life measurements, showing the relationship between the steel melt chemistry O ppm, % C, slag composition % FeO, and specific electrical energy consumption and steel melt yield during electric arc furnace refining stage. The results emphasize the significance of fixing the proper oxidation time during the refining stage for the desired steel grade.
In this research work, deep machine learning-based methods together with a novel data augmentation are developed for predicting flicker, voltage dip, harmonics, and interharmonics originating from ...highly time-varying electric arc furnace (EAF) currents and voltage. The aim with the prediction is to counteract both the response and reaction time delays of active power filters (APFs) specifically designed for electric arc furnaces (EAF). Multiple synchronous reference frame (MSRF) analysis is used to decompose the frequency components of the EAF current and voltage waveforms into dqo components. Then using low-pass filters and prediction of the future values of these dqo components, reference signals for APFs are generated. Three different methods have been developed. In two of them, a low-pass Butterworth filter is used together with a linear finite impulse response (FIR)-based prediction or long short-term memory network (LSTM) for prediction. In the third method, a deep convolutional neural network (CNN) combined with a LSTM network is used to filter and predict at the same time. For a 40-ms prediction horizon, the proposed methods provide 2.06%, 0.31%, 0.99% prediction errors of the dqo components for the Butterworth and linear prediction, Butterworth and LSTM, and CNN with LSTM, respectively. The error of the predicted reconstructed waveforms of flicker, harmonics, and interharmonics resulted in 8.5%, 1.90%, and 3.2% reconstruction errors for the abovementioned methods. Finally, a Simulink and GPU-based implementation of predictive APF using Butterworth filter + LSTM and a trivial APF resulted 96% and 60% efficiency on compensation of EAF current interharmonics.
Utilizing Electric arc furnace slag (EAFS) as a precursor for alkali-activated mortar production reduces waste and supports alternative cement binders. Since the mix design includes multiple factors, ...the Taguchi DoE was employed by varying the modifier (fly ash) to precursor (EAFS) ratio (0–75% by mass), activator to precursor ratio (A/P) (0.52–0.66), sodium hydroxide (SH) concentration (8–14 M), and sodium silicate to sodium hydroxide ratio (SS/SH) (1.5–3.0). Analytic hierarchy process (AHP) weighted Grey relational analysis (GRA), and technique for order preference by similarity to ideal solution (TOPSIS), were utilized to achieve a high performing mix. Performance characteristics encompass flowability (flow%), final setting time (FST), compressive strength (f'cu), and flexural strength (f'cr). The optimized mix possessed 75% flowability, 575 min FST, 38 MPa f'cu, 16 MPa f'cr, and 3.75% water absorption. Precursor-to-modifier ratio dominates the mix design. The three mixes—optimized (M17), top-ranked (M8), and least-ranked (M1) were micro-structurally examined using powdered X-ray diffraction, X-ray fluorescence, scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy.
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•Development of sustainable alkali-activated EAF slag-based mortar.•DoE using Taguchi and optimization using hybrid AHP-GRA and TOPSIS.•Validation experiment on optimal mix confirming optimization results.•High f'cu ∼38 MPa, low Wabs 3.75%, good flow 75%, adequate setting time 575 min.•Development of geopolymeric gel substantiated through SEM-EDS, XRD, and FTIR.
This work analyses the environmental impact of using electric arc furnace slags as secondary raw material in pavement and its comparison with the traditional materials used in road construction. ...Chemical and technical evaluations of the main characteristics of the black slags as coarse aggregate were carefully developed.
The environmental analysis was carried out by using the Life Cycle Assessment methodology. The Life Cycle Inventory data was processed to obtain emissions grouped in terms of impact categories based on the Centre of Environmental Science of Leiden University baseline method at midpoint level. The results obtained revealed that some of the most relevant environmental impacts, such as carbon footprint, abiotic depletion, ozone layer depletion and photochemical oxidation, depend highly on the road construction processes, although, in the two scenarios analysed, the bitumen production was demonstrated to be the most contributing stage.
These indicators also concluded that important environmental benefits could be obtained from the use of black slag as course aggregate in road construction. Consequently, the results shown here could be added to the list of technical criteria for their inclusion into a multi-objective optimisation methodology.
•Use of electric arc furnace slag as a substitute of natural aggregates was analysed.•Technical and chemical characterisations of the slags were addressed.•These slags met the legal requirements to be used as aggregate in road construction.•Natural and slag derived aggregates were compared by using life cycle assessment.•The environmental impact of road construction can be reduced by using slags.
•EAFS provided around 85% fuel conversion during utilization as OC in CLC.•The reactivity of EAFS increased substantially at the beginning of the CLC tests.•This fact was defined as “activation” of ...the OC between 1st–15th RHCs.•After “activation”, the reactivity of EAFS became stable till the end of the tests.•EAFS is a viable OC candidate for CLC, but its iron content should be enriched.
The aim of this study was to assess the feasibility of an electric arc furnace slag (EAFS) sample from Turkey as oxygen carrier (OC) in syngas-fueled chemical-looping combustion (CLC) process. The CLC tests were performed at 800 °C fluidized bed conditions for 50 cycles using CO and H2 gases to constitute fuel atmospheres. EAFS exhibited an “activation behavior” which was characterized by a substantial increase on reactivity throughout the first 15 cycles of all tests. After that point, the reactivity of the OC became almost stable and more than 85% mean fuel gas conversion was obtained in all tests. Considering the abovementioned fuel conversion efficiency and the low cost of the EAFS it is concluded that, provided that the iron content can be increased by means of floating or magnetic separation techniques, the utilization of EAFS as OC may be both environmentally benign and favorable in terms of CLC technology.
•Fine and coarse EAF slag aggregates were incorporated into Roller-compacted concrete.•Incorporating coarse EAF slag led to promote mechanical and fracture properties.•Positive effect of coarse slag ...inclusion for mode II fracture toughness was more than that of mode I state.•Flexural strength exponentially is related to the broken aggregate fraction of fracture face.•Pull-off results demonstrated the negative effect of fine EAF on the splitting tensile strength.
The present study made an effort to investigate effect of partial and full replacement of natural aggregate with the Electric Arc Furance (EAF) steel slag on the mechanical and fracture properties of Roller Compacted Concrete (RCC). Various concrete mixtures containing fine and coarse EAF steel slag were prepared to find out the impact of each part on the performance of RCC mortar and concrete mixture. To investigate mechanical properties of the mixtures specimens of RCC, different tests were performed, including the splitting tensile, compressive, semi-circular bending and three-point bending tests. The Results showed that fine and coarse EAF steel slag had different impacts on the mechanical properties of the RCC. The results showed that for fine aggregate replacement, obtained mechanical responses decreased by increase in the amount of EAF steel slag, which have the high specific surface area. Besides, incorporating the coarse EAF steel slag increased aggregate interlock mostly due to its high angularity and roughness causing to promote the mechanical and fracture properties. The investigated broken aggregate fraction on the fracture face of beams by image processing and pull-off test results confirmed the mentioned findings.
•EAF slag as coarse aggregate substitution decreases compressive strength and sulfate resistance of RCCP.•Replacing natural aggregate by EAF slag increases water absorption and abrasion resistance of ...RCCP.•20% fly ash as cement alternative improves compressive strength and durability properties of slag-RCCP at long-term age.•The weathering treatment process reduces the expansive potential of EAF slag.•EAF slag is non-active aggregate by alkali-silica reaction.
This study investigates the effects of electric arc furnace (EAF) slag aggregate and fly ash on compressive strength and durability properties (i.e. water absorption, abrasion resistance, and sulfate resistance) of roller-compacted concrete pavement (RCCP). The EAF slag aggregate as natural aggregate substitution was used at three levels (i.e. 0%, 50%, and 100%) and cement was replaced by fly ash at three ratios (i.e. 0%, 20%, and 40%). The EAF slag aggregate used in this study was exposed to outdoor condition for several months to reduce the volume instability. The RCCP mixing proportions were determined by soil compaction method. The compressive strength of RCCP was examined at 3-, 7-, 28-, and 91-day age. Meanwhile, the water absorption, abrasion resistance, and sulfate resistance of RCCP at 91-day age were used to study the durability properties. Furthermore, the length change of mortar bars made with EAF slag aggregate was measured to evaluate the expansive potential of EAF slag caused by autoclave condition and alkali-silica reaction (ASR) condition. Additionally, X-ray diffraction analysis was offered to identify the crystalline phases of mortar patterns under autoclave and ASR testing condition. The results presented that the compressive strength and sulfate resistance of RCCP containing EAF slag aggregate declined slightly, whereas the water absorption and abrasion resistance increased in comparison to those of traditional RCCP. Besides, the use of fly ash as cement substitution improved the compressive strength of slag-RCCP at long-term age. A replacement of 20% fly ash provided the slag-RCCP fulfilling the strength and durability requirements for pavement. In addition, the expansion in terms of length change of mortar bars indicated that EAF slag aggregate after the proper treatment performed the volume stability under the autoclave condition and ASR test.
•The characterization, applications, and performance of steel slag are addressed.•An approach of hardness and grindability is presented.•Expansive characteristics of steel slag and mitigation ...mechanisms are discussed.•Presence of toxic elements (Cr, Ni, V) is treated in environmental classification.•Durability parameters of cement-based composites with steel slag are portrayed.
Steel slags are by-products generated in high volumes in the steel industry. Their main constituents are calcium, silicon, ferric, aluminum, and magnesium oxides. Larnite, alite, brownmillerite, and ferrite are also found. The presence of expansive compounds cause concern when used in cement-based composites; however, mitigating routes have been proposed. Activation techniques improve the binding properties of steel slag powder, potentiating its use as a supplementary cementitious material (SCM). As an aggregate, steel slag presents good morphological and mechanical properties. Promising mechanical and durability performances in cement-based composites encourage further research to promote the use of steel slag.
A strategy of the power-electronics-based emulation of the electric arc furnace (EAF) in the laboratory has been developed. The generalized predictive power control strategy is used in the emulation. ...The EAF emulation is capable faithfully emulate the operation of the EAF using measured data from a real EAF operation. Thus, the developed strategy enables the real-time emulation of the EAF with its under-scaled control components in various modes of operation in laboratory conditions. As an example, a small-scale active power filter (APF) and static var compensator (SVC) used for flicker mitigation were included as parts of the laboratory system. Selected results of simulation and experimental tests in the laboratory using the data collected from the real 60 t EAF are presented and discussed.
In this article, a new approach to compensate both the response and reaction times of active power filters (APF) for special cases of highly time-varying harmonics and interharmonics of electric arc ...furnace (EAF) currents is proposed. Instead of using the classical approach of taking a window of past current samples and analyzing the data, future samples of EAF currents are predetected using a deep learning (DL)-based method and then analyzed, which provides the opportunity to make real-time analysis. This can also serve the needs of other possible APF applications. Two different methods for prediction of future samples of harmonics and interharmonics have been proposed: predetection of harmonics and interharmonics in the time domain (TD) and in the frequency domain (FD). To obtain the best possible accuracy for both methods, grid search has been employed for parameter optimization of the DL structure. Both TD and FD approaches have been tested on field data, which had been obtained from transformer substations supplying EAF plants. It is shown that the response time of the APF algorithms can be compensated using the TD-based approach, while it is possible to compensate both the response and reaction times of APFs using the proposed FD-based approach. The developed method can be considered to be a feasible candidate solution for generating reference signals for the controllers of new generation of compensation devices, which can be referred to as predictive APFs.
