Electric Arc Furnace Steelmaking Research Articles

Effect of hot metal charging on economic and environmental indices of electric arc furnace steelmaking in China

Hot metal (HM) charging electric arc furnaces (EAF) with good production indices and economic benefits have been widely used in China. In this study, the economic and environmental indices of EAF were analyzed based on a mechanistic process model, and the energy consumption, carbon emissions, and production costs with different hot metal ratios (HMRs) were obtained. There are strong correlations between HMR and the energy consumption, carbon emissions, and production costs of EAF. The Pareto optimal solution for the current state is 50% HMR-EAF, which produces carbon emissions of 1402.68 kg-CO2/t and a production cost of 3609.40 CNY/t. Considering the current situation in China, this process is more in line with the need to coordinate the economic and environmental indices of steel plants compared to direct reduced iron (DRI)-EAF, scrap-EAF, and blast furnace-basic oxygen furnace (BF-BOF) processes. Moreover, it has the potential to be more easily realized and promoted.

Influence Factor Analysis and Prediction Model of End-Point Carbon Content Based on Artificial Neural Network in Electric Arc Furnace Steelmaking Process

In this manuscript, we consider the accuracy of end-point carbon content prediction affected by oxygen injection in multiple stages of electric arc furnace (EAF) melting process. Such a prediction would help to further evaluate process control strategies and optimize overall operation of the electric arc furnace. Principal component analysis (PCA) was used to normalize the 13 input variables affecting the endpoint carbon content. log-sigmoid and tan-sigmoid functions were used to verify the same sample, and it was found that the Mean squared error(MSE) of the model under logsig + logsig function was smaller, indicating that the model was more stable. At the same time, different hidden layer nodes were tried, and finally the structure of the model was determined as 13 × 10 × 8 × 1, and the activation function was logsig + logsig. Using historical smelting data to train and test the neural network model, the correlation coefficient (R) of the verified model is 0.7632, the model prediction is in the range of ±0.03%, the hit rate of the model is 64.5%, and the hit rate of the model is 42% in the range of ±0.02%. Combining the verification basis of the model with the metallurgical reaction principle of the EAF steelmaking process, a pretreatment method of phased input of total oxygen is proposed. The oxygen is divided into three stages, which are the oxygen consumption volume of 0–5 min, 5–30 min and more than 30 min and other variables are kept unchanged. The same neural network is used to train and verify the same data. After verification, the R of the oxygen staged model is 0.8274. The model prediction is in the range of ±0.03%, the hit rate of the model is 78.5%, and the hit rate of the model is 58% in the range of ±0.02%. Finally, an on-line carbon content prediction system based on artificial neural network model is developed and applied to actual production. Running results illustrated that the hit rate of end-point carbon content is 96.67%, 93.33% and 86.67%, respectively when the prediction errors are within ±0.05%, ±0.03% and ±0.01%, the improved neural network model can effectively predict the end-point carbon content, which provides a good basis for the carbon content at the end point of EAF steelmaking process.

Prediction Model of End-Point Phosphorus Content in EAF Steelmaking Based on BP Neural Network with Periodical Data Optimization

The phosphorus (P) content of molten steel is of great importance for the quality of steel products in the electric arc furnace (EAF) steelmaking process. At present, the initial conditions of smelting process in the prediction of end-point P content are still the core part. However, few studies focus on the influence between process data and end-point P content. In this research, the relationships between process data and end-point P content are explored by a BP neural network. Based on the theoretical analysis, influencing factors with high correlation were selected. The prediction model of P content coupled with process data and end-point P content is established. On this basis, the model is optimized with process data of oxygen supply and the time of the first addition of lime. Compared with the practical production data, the results indicate that the hit rate of the model optimized is 87.78% and 75.56% when prediction errors are within ±0.004 and ±0.003 of P content. The model established has achieved the effective prediction for end-point P content, and provided a reference for the control of P content in practical production.

Regulation of Slag Mode of Steelmaking in Electric Arc Furnace by Controlling Electrical Parameters during Oxidation at Melting

Regulation of Slag Mode of Steelmaking in Electric Arc Furnace by Controlling Electrical Parameters during Oxidation at Melting

Numerical simulation on the melting kinetics of steel scrap in iron-carbon bath

Steel scrap melting kinetics is a key factor that affects the scrap ratio and temperature trajectory of Basic Oxygen Furnace steelmaking process and the productivity and energy utilization of Electric Arc Furnace steelmaking process. In this paper, the interface between steel scrap and melt is analyzed and a novel theoretical model of steel scrap melting in iron-carbon bath is established. Moreover, the effects of bath temperature, bath carbon content, preheating temperature and characteristic length of steel scrap on the melting rate of steel scrap, mass transfer coefficient of carbon, heat transfer coefficient and interface carbon concentration were investigated. The results show that the ultimate steady melting rate increases from −2.04 × 10 −4 to −3.32 × 10 −3 m/s with the increases of bath temperature from 1793 K to 1873 K, the ultimate steady heat and mass transfer coefficient first increase and subsequently decrease, are in the range of 1.04 × 10 5 to 2.86 × 10 5 W/m 2 /K and 0 to 2.89 × 10 −4 m/s, respectively. As the bath carbon content increase from 1.0 wt% to 4.0 wt%, the ultimate steady melting rate increases from −8.85 × 10 −5 to −3.23 × 10 −4 m/s, the ultimate steady heat transfer coefficient first increases and subsequently decreases, is in the range of 7.59 × 10 4 to 1.01 × 10 5 W/m 2 /K. Furthermore, the ultimate steady mass transfer coefficient and the ultimate steady interface carbon content gradually decreases from 1.40 × 10 −4 to 5.21 × 10 −5 m/s and from 0.73 to 0.69 wt%, respectively. With the increase of preheating temperature and characteristic length of steel scrap, the ultimate steady melting rate, heat transfer coefficient between steel scrap and melt, mass transfer coefficient and interface carbon concentration remain almost constant, about −8.85 × 10 −5 m/s, 8.40 × 10 4 W/m 2 /K, 1.40 × 10 −4 m/s and 0.70 wt%, respectively.

Effect of coherent jet burner on scrap melting in electric arc furnace

Modern electric arc furnace (EAF) steelmaking relies on the coherent jet burner to melt scrap at the cold spots inside the furnace, but the relevant computational fluid dynamics (CFD) modeling of this process has not been reported and systematically studied. The present work established an innovative comprehensive CFD model including a scrap melting model and a coherent jet model based on the detailed physical principles, which couples the solid–liquid-gas three-phase system with coherent jet and scrap melting/re-solidification for the investigations of key evaluation factors including burner efficiency, scrap heating rate, and scrap melting cavity. An experiment was designed and implemented specifically in an industrial-scale EAF for validating the proposed model. The model was employed to explore the impacts of burner power, scrap porosity, scrap preheat temperature, and scrap blockage on burner energy utilization. An understanding and guidance of coherent jet burner operations were provided based on the studies for more effective scrap melting.

Influence of different central nozzle diameters and powder injection rates on carbon powder mixed injection with shrouding supersonic oxygen jet (CMISSO) lance

ABSTRACT In order to improve the carbon powder utilization efficiency in electric arc furnace (EAF) steelmaking process, the carbon powder mixed injection with shrouding supersonic oxygen jet (CMISSO) lance was designed. In this study, the effects of different central nozzle diameters and powder injection rates on the dynamic characteristics of CMISSO lance are studied by numerical simulation, and the reliability of numerical simulation is verified by cold test. The results show that when the diameter of the central nozzle is 10, 15 and 20 mm, the mixing distance is 0.18, 0.28 and 0.30 m. Depicting that 10 mm centre nozzle diameter is the easiest to merge the central jet and the shrouding jet. The application of CMISSO injection lance can effectively make the powder get together. In addition, the larger the powder flow, the larger the powder distribution range and the lower the utilization efficiency.

Suitability of Self‐Reducing and Slag‐Forming Briquettes for Electric Arc Furnace Use Based on Laboratory Tests

The in-plant recycling routes of several side streams produced in Electric Arc Furnace (EAF) steelmaking remain under-explored. In article 2100472, Abdelrahim and co-workers characterize eight side streams and use them to produce seven different briquettes. Briquettes are assessed for their suitability to be used in EAF through a series of mechanical and high-temperature tests, reflecting their intended use.

Efficient extraction and separation of zinc and iron from electric arc furnace dust by roasting with FeSO4·7H2O followed by water leaching

Electric arc furnace dust (EAFD) formed during steelmaking in electric arc furnace is rich in iron and zinc. Due to the negative effects of zinc, directly recycling as raw materials for ironmaking does not work so that it is still mostly accumulated. In this study, a novel process was proposed, wherein EAFD was roasted with FeSO4·7H2O followed by water leaching for the effective and selective extraction and separation of zinc and iron from EAFD. The optimal roasting conditions were determined as mass ratio of FeSO4·7H2O/EAFD of 1.5, roasting temperature of 675 °C, holding time of 3 h. The transfer mechanism of elements in EAFD was analyzed. 98.79% of zinc and only 0.11% of iron were dissolved in the leaching solution, respectively, avoiding the iron-removing step before the subsequent zinc electrodeposition. Meanwhile, most of Ca, Mg and Mn ions transformed into corresponding sulfates during roasting experiments and then entered leaching solution after water leaching. Thus, the leaching residue with 91.36% mass ratio of Fe2O3 could be applied as raw material for ironmaking industry. In addition, the majority of heavy metals (Pb and Cr) were remained and immobilized in the leaching residue, meeting the requirement of leaching toxicity standard. Results from this work provide a new insight into selective recovery of valuable metals from EAFD while at the same time exploiting the solid waste of Copperas.

Study on oxygen blowing optimisation of reducing (FeO) content in slag in EAF steelmaking process with high ratio of hot metal to scrap

ABSTRACT The aim of the study was to address the challenge – in a particular plant – of the high (FeO) content in slag in Electric Arc furnace (EAF) steelmaking, adopting a high ratio of hot metal to scrap, which uses the operation mode of adding hot metal and smelting simultaneously, the oxygen blowing process was optimised through a combination of industrial practice and theoretical calculation. Specifically, the start time of oxygen blowing was delayed, and the [C] content of the molten steel at the smelting endpoint was increased; furthermore, an oxygen blowing method was performed with a [C] content of 0.6–0.8% for the molten bath during the smelting process. After the oxygen blowing method was optimised, the oxygen consumption per ton of steel decreased by 7.96 Nm3, and the (FeO) content of slag decreased by 11.85% on average.

РОЗВИТОК КОНЦЕПЦІЇ ПІДВИЩЕННЯ ЕНЕРГОЕФЕКТИВНОСТІ ДУГОВОЇ СТАЛЕПЛАВИЛЬНОЇ ПЕЧІ ШЛЯХОМ УТИЛІЗАЦІЇ ТЕПЛОТИ ДИМОВИХ ГАЗІВ ДЛЯ ПОПЕРЕДНЬОГО НАГРІВУ СКРАПУ

An important factor in improving the energy efficiency of the electric arc steelmaking furnace (EAF) is utilization of the flue gas energy to preheat the initial charge. Implementation of the process in existing EAF requires the measures to synchronize with the carbon monoxide post combustion and to prevent of the toxic PCDD/F formation when conventional scrap heating, which is significantly complicated in a traditional scheme of CO afterburning with a single-stage air inflow through a temperature and concentration factors. The technological basics of medium-temperature scrap preheating by EAF flue gas have been developed and substantiated. Numerical study of carbon monoxide burning thermodynamics and kinetics shown that implementation of two-stage inflow of air into postcombustion chamber for stoichiometric combustion of CO and cooling the heat carrier provides a comprehensive solution of mentioned problems. The ratio of primary and secondary flows 1 to 3.5 provides allowable concentration of carbon monoxide in the ducts; obtaining gas mixture with a temperature of up to 500 °C, which prevents PCDD/F formation; acceptable temperature operating conditions of bag fabric filters of the gas cleaning system within 100 °C regardless of scrap preheating. Numerical simulation of the heat exchange process between the charge layer and the gaseous heat carrier reveal that shredder scrap of standard bulk density 0.9 t/m3 and mass of half EAF capacity can be preheated up to temperature of 450 °C in 18-20 minutes. Given value corresponds to the duration of technological period in the EAF heat cycle, characterizing by comparatively stable emission and maximal temperature of the flue gas flow. Reduction of the scrap fragments bulk density and the average size, as well as increasing the ratio of the heating chamber height to its diameter in the range from 0.7 to 2.0, promotes the heating rate magnification. The technology provides specific energy savings within 20-30 kW.h per ton of steel and can be implemented in existing electric steelmaking shop of the mini-mill without additional CO2 emissions. The payback period for a 50-ton EAF with annual productivity of 400-450 thousand tons of steel is 14-18 months.

Occurrence of chlorinated and brominated polycyclic aromatic hydrocarbons from electric arc furnace for steelmaking

Chlorinated and brominated polycyclic aromatic hydrocarbons (Cl/Br-PAHs) are persistent organic pollutants with potential carcinogenic toxicities that are even higher than those of their parent PAH congeners. Current knowledge of Cl/Br-PAH sources and emission characteristics is lacking. Electric arc furnace (EAF) steelmaking is a potential source for Cl/Br-PAHs, considering that preheating of raw materials before they enter the EAF could produce suitable conditions for Cl/Br-PAHs formation. In this field study, we identified EAFs as an important source of Cl/Br-PAHs and clarified their emission concentrations, fingerprints by gas chromatography coupled with high-resolution magnetic mass spectrometry. Potential formation mechanisms of Cl/Br-PAHs were also proposed. The mass concentration ranges for Σ18Cl-PAHs and Σ18Br-PAHs in stack gas were 25.85–4191 ng Nm−3 and 1.02–341 ng Nm−3, respectively. The variation of concentration indicated that the steel scrap composition greatly affected the production of Cl/Br-PAHs. The congener ratios including 6-chlorobenzo [a]pyrene/3-chlorofluoranthene and 1-chloroanthracene/1-chloropyrene could be used to estimate the influence of industrial sources on Cl-PAH occurrences in the air. Ring structure growth was the dominant formation pathway for Cl/Br-PAHs, distinctly different from dioxin formation mechanisms dominated by precursor dimerization and chlorination.

A combined hydro-pyrometallurgical process for zinc oxide and iron oxide extraction from electric arc furnace dust waste

Electric arc furnace (EAF) dust waste is generated during EAF steelmaking process. Zinc and iron which comprise the highest composition in EAF dust are secondary resources for making steel products. They mainly present in the form of stable zinc ferrite (ZnFe2O4), leading to the extraction process difficult. In this study, a combined hydro-pyrometallurgical process was developed to extract both zinc oxide and iron oxide from EAF dust. Initially, hydrometallurgical leaching was used to leach zinc and iron from EAF dust. Results show that 10 M of hydrochloric acid (HCl) at 25°C can achieve zinc and iron leaching of 92% and 91%, respectively. The liquid solution post leaching was subjected to pyrometallurgical process to form Fe2O3 mixture at 250°C while retaining zinc chloride (ZnCl2) as solid residue. Then, the obtained ZnCl2 was treated with sodium hydroxide (NaOH) and nitric acid (HNO3) to form ZnO. The Fe2O3 and ZnO extraction were 2.5 g and 1.5 g, respectively out of 10 g of EAF dust with their respective purity of 87% and 98%. The developed process can provide new insight into recovering zinc oxide and iron oxide simultaneously from EAF dust, thereby paving the way to circular economy development and sustainable steel dust waste management for steel industries.

Suitability of Self‐Reducing and Slag‐Forming Briquettes for Electric Arc Furnace Use Based on Laboratory Tests

The in‐plant recycling routes of side streams produced in electric arc furnace (EAF) steelmaking remain underexplored. Briquetting is an attractive technique to enable their recycle. Briquettes introduced into EAF must possess certain mechanical and chemical properties. However, no standard is available to determine the suitability of briquettes used in the EAF process. Herein, eight side streams are characterized, and used to produce seven different briquettes to be used in EAF. Briquettes tested consist of four self‐reducing briquettes and three slag‐forming briquettes produced using different recipes. The briquettes are subjected to several mechanical and thermal tests which reflect their intended use in EAF. The mechanical tests include compression and drop tests, and the thermal tests include optical dilatometry, thermogravimetric analysis (TGA)–derivative thermogravimetry (DTG)–mass spectrometry (MS), and full‐scale briquette reduction tests. Moreover, melting trials are performed to assess the melting behavior of selected briquettes and their interaction with slag. Suitability of briquettes characteristics is assessed based on values from the literature and against reference ferroalloys and lime stones used in one of the steel plants. Two briquettes are deemed suitable for EAF use, while three briquettes are deemed unsuitable, and two briquettes are considered of limited use.

Interaction Behavior of Biogenic Material with Electric Arc Furnace Slag

Electric arc furnaces (EAFs) are used for steel production, particularly when recycling scrap material. In EAFs, carbonaceous material is charged with other raw materials or injected into molten slag to generate foam on top of liquid metal to increase energy efficiency. However, the consumption of fossil carbon leads to greenhouse gas emissions (GHGs). To reduce net GHG emissions from EAF steelmaking, the substitution of fossil carbon with sustainable biogenic carbon can be applied. This study explores the possibility of the substitution of fossil material with biogenic material produced by different pyrolysis methods and from various raw materials in EAF steelmaking processes. Experimental work was performed to study the effect of biogenic material utilization on steel and slag composition using an induction melting furnace with 50 kg of steel capacity. The interaction of biogenic material derived from different raw materials and pyrolysis processes with molten synthetic slag was also investigated using a tensiometer. Relative to other biogenic materials tested, a composite produced with densified softwood had higher intensity interfacial reactions with slag, which may be attributed to the rougher surface morphology of the densified biogenic material.

Effect of Slag Composition on Dephosphorization and Foamability in the Electric Arc Furnace Steelmaking Process: Improvement of Plant Operation

Effect of Slag Composition on Dephosphorization and Foamability in the Electric Arc Furnace Steelmaking Process: Improvement of Plant Operation

Melting characteristics of alternative charging materials in an electric arc furnace steelmaking

ABSTRACT The data obtained on 220-T ultra-high power electric arc furnace (EAF) were analysed in order to study the impact of DRI quality on the steelmaking process parameters and consumption of lime, coke, oxygen, natural gas, electrical energy and electrodes. In addition, the effects of charging methods and proportions of DRI in an EAF were studied. It was found that by increasing the proportion of non-high quality reduced pellets and/or HBI to 45% of the metallic charge, the steel yield decreased to 85.32% and increased to 87.57% when between 75 and 100% continuous feeding of high quality reduced pellets. This resulted in saving 21 min in tap-to-tap time and 7% of the electrode consumption. Charging high proportion of non-high quality DRI from 45% to 100% in EAF, leads to a loss of 4 tons/heat in liquid steel, and an increase in lime consumption from 4 to 6 kg/ton liquid steel.

Emissions of polychlorinated naphthalenes during electric arc furnace steelmaking and their influencing factors

Emissions of polychlorinated naphthalenes during electric arc furnace steelmaking and their influencing factors

Investigation of composition and properties of EAF dust for metal reduction

In this work, we investigated the composition and structure of the dust of electric arc steelmaking furnaces. We considered the process of direct reduction of metals (mainly Zn and Fe) with biochar from EAF dust. For better control over chemical transformations, it is proposed to use microwave heating of a mixture of EAF dust and biochar. Possible chemical and phase transformations for complex oxides in the composition of EAF dust have been determined.

Energy system requirements of fossil-free steelmaking using hydrogen direct reduction

The iron and steel industry is one of the world's largest industrial emitters of greenhouse gases. One promising option for decarbonising the industry is hydrogen direct reduction of iron (H-DR) with electric arc furnace (EAF) steelmaking, powered by zero carbon electricity. However, to date, little attention has been given to the energy system requirements of adopting such a highly energy-intensive process. This study integrates a newly developed long-term energy system planning tool, with a thermodynamic process model of H-DR/EAF steelmaking developed by Vogl et al. (2018), to assess the optimal combination of generation and storage technologies needed to provide a reliable supply of electricity and hydrogen. The modelling tools can be applied to any country or region and their use is demonstrated here by application to the UK iron and steel industry as a case study. It is found that the optimal energy system comprises 1.3 GW of electrolysers, 3 GW of wind power, 2.5 GW of solar, 60 MW of combined cycle gas with carbon capture, 600 GWh/600 MW of hydrogen storage, and 30 GWh/130 MW of compressed air energy storage. The hydrogen storage requirements of the industry can be significantly reduced by maintaining some dispatchable generation, for example from 600 GWh with no restriction on dispatchable generation to 140 GWh if 20% of electricity demand is met using dispatchable generation. The marginal abatement costs of a switch to hydrogen-based steelmaking are projected to be less than carbon price forecasts within 5–10 years.