Melting Furnace Research Articles

System Identification for Robust Control of an Electrode Positioning System of an Industrial Electric Arc Melting Furnace

Through system identification for robust control methods and utilizing real-time experimental field data, a comprehensive mathematical model is derived that represents the dynamic performance of a single electrode positioning system (EPS) in an industrial electric arc melting furnace (EAF). This EPS is characterized by large, time-varying dynamic parameters, which fluctuate based on operating conditions, specifically as the electrode weight changes within its operational range. The system identification methodology for robust control is developed in four main steps, progressing from experimental design to model validation. This approach yields a nominal model of the actual system and provides a trustworthy estimate of the region of uncertainty of the model, bounded by models of the real system under maximum and minimum electrode weight conditions (limit operating models). The methodology generates three fourth-order time-delay models using an ARMAX structure. The results are promising, as system identification for robust control enables the derivation of mathematical models specifically tailored for designing robust controllers. These controllers significantly enhance the EPS control system’s performance and substantially reduce energy consumption and environmental emissions.

Iron extraction from dust from scrap metal smelting in electric arc furnaces by magnetic separation

Iron extraction from dust from scrap metal smelting in electric arc furnaces by magnetic separation

Numerical Study of Hydrogen-Rich Fuel Coherent Jet in Blast Furnace Tuyere

Injecting hydrogen-rich fuel into blast furnaces is an effective strategy to reduce carbon dioxide (CO2) emissions. The present study established a three-dimensional (3D) model based on a coherent jet of hydrogen-rich fuel. The combustion characteristics and the flow, heat, and mass transfer behaviors in the reaction region were simulated by the Computational Fluid Dynamics (CFD) method. The effects of fuel jet velocity on the distributions of gas velocity, temperature, and species in the reaction region were systematically analyzed. The results show that hydrogen-rich fuel burned around the main jet, generating a high-temperature, low-density flame. As flame length increased, the main jet experienced less decay. The outward expansion of the jet caused continuous diffusion of gas temperature and its components. As the fuel jet velocity increased, the temperature along the main jet centerline rose sharply, while the length of the high-concentration gas region extended. Doubling the jet velocity increased its centerline velocity by 11% and raised the average reaction region temperature by 4.12%. The obtained highlighted results are of paramount importance for optimizing hydrogen-rich smelting in blast furnaces.

On the use of hydrogen in oxy-fuel glass melting furnaces: An extensive numerical study of the fuel switching effects based on coupled CFD simulations

The present study examined the potential of utilizing hydrogen as a fuel in an industrial cross-fired oxy-fuel glass melting furnace with a total energy input of 3.9 MW. To this end, comprehensive three-dimensional CFD simulations were performed in Ansys Fluent, employing a coupled numerical model from preceding works. A two-step validation process was presented, comprising the validation of both the numerical furnace setup and the modeling of industrial oxy-fuel combustion setups using hydrogen as a fuel gas. Assuming an equal thermal energy input for both combustion conditions, the fuel/oxidizer ratios of velocity and momentum of the six PrimeFire burners were found to be significantly affected. Consequently, the low-momentum flames with natural gas transformed into jet-type flames with a straighter trajectory when transitioning to hydrogen. This change led to an enhanced turbulent mixing and a reduction of flame lengths by over 25%, while the average flame temperature increased by up to 82 K due to the accelerated reaction kinetics. In addition, the elevated flame momentum in the cross-fired burner configuration resulted in a localized rise in maximum side wall temperatures by more than 20 K. With the exception of these local effects, the global temperature distribution and heat transfer mechanisms were not significantly impacted. This indicated a comparable melting process and furnace efficiency, while still allowing for a reduction of total CO2 emissions by 77.5%. Future research should concentrate on both the impact on glass quality and the evaluation of potential alternative burner configurations for hydrogen-fired oxy-fuel glass melting furnaces.

Properties evaluation of electric smelting furnace slag: Viscosity and sulfide capacity under different FeO content

This study investigated the viscosity and sulfide capacity of electric smelting furnace (ESF) slag (CaO-SiO2-6wt.%MgO-10 wt%Al2O3-FeO) with a basicity of 0.8 through cylinder rotating method and gas-slag equilibrium experiments. Additionally, the high-temperature structure of the slag was analyzed using FTIR and Raman spectroscopy. The results showed that as the FeO content increased from 1 wt% to 9 wt%, the viscosity of the ESF slag gradually decreased, with a more pronounced reduction observed when the FeO content exceeded 5 wt%. The increase in FeO content led to a reduction in the initial liquidus temperature, resulting in the formation of a greater amount of liquid phase at lower temperatures. Furthermore, FeO released O2− ions at high temperatures, which depolymerized the silicate network structure, thereby reducing the viscous flow resistance. These dual effects of FeO contributed to the decrease in slag viscosity. In addition, the sulfide capacity of the slag increased with rising FeO content, and the activity order of sulfides in the slag was FeS > CaS > MgS. This was because Ca2+ ions were largely consumed for charge compensation within the silicate structure in the low-basicity slag. Based on these findings, during the ESF furnace smelting process, the desulfurization step should preferably be conducted at the front end of the reduction process.

Improvement of the efficiency of blast furnace smelting technology with pulverized coal fuel injection

Improvement of the efficiency of blast furnace smelting technology with pulverized coal fuel injection

Prediction model of permeability index for blast furnace based on WD-NL-transformer

The permeability index is an important variable to reflect the operating state of a blast furnace quickly, intuitively and comprehensively. Given the multi-scale, nonlinear and massive characteristics of the blast furnace smelting process data, a prediction model of permeability index based on the WD-NL-transformer (wavelet de-noising-nonlinear-transformer) method was proposed. The key variables affecting permeability index were selected from multiple perspectives by Pearson correlation coefficient and copula entropy. The extreme outliers were optimised using box plots and Lagrange linear interpolation. A data set was constructed after wavelet de-noising to build the prediction model with nonlinear processing capability, time-series prediction capability, and early stopping method. The results show that the MSE of WD-NL-transformer is 0.0093, with the RMSE of 0.0086. Meanwhile, the R2 is 0.9859, and the running time is 19.59 s, which means the model has great prediction accuracy and inference speed. The proposed model could provide theoretical support for advanced control of permeability index, which is of practical significance to ensure the stability of blast furnace smelting and accelerate the metallurgical process of intelligent automation.

The effect of complex extra-furnace treatment of metal melts on the formation of non-metallic inclusions in large-sized ingots

Abstract The article presents the results of studying non-metallic inclusions (NI) after extra-furnace treatment of the 13Cr9Mo2Co1NiVNbNB steel melt to produce large-sized ingots. The objects of the study were laboratory samples melted in a semi-industrial induction furnace with the capacity of 20 tons (the first batch), and samples obtained after melting in an electric arc furnace with the capacity of 120 tons, followed by modification and double vacuuming (the second batch).
Previously, using the Fact Sage software, modeling of the NI formation processes was carried out. The data were obtained on the possible NI composition and amount in this steel.
Studying NIs (the composition, the contamination index, inclusion parameters) was carried out on an ASPEX Explorer electron microscope using the method of automatic X-ray spectral analysis of particles (Automatic Features Analysis, AFA). It was established that in the samples of the first batch, the main part of the NIs consisted of chromium- and manganese-containing oxides: chromium-manganese spinels (Cr-Mn-O and Mn-Cr-Si-O groups), which occupy more than 94% of the total area of the NIs. In the samples of the second batch, the main part of the Nis was represented by Cr-Mn-O; Al-Cr-O; Cr-Al-Mn-O systems.
It was shown that the average size of non-ferrous substances in the samples of the laboratory batch and in industrial samples after extra-furnace treatment differs slightly (5-12%), however, the contamination index in industrial samples after vacuum treatment and especially after modification and repeated vacuum treatment was reduced by more than 10 times. The results obtained allow recommending vacuum treatment and complex modification with calcium and boron as measures to prevent the formation of non-ferrous metals and to improve metallurgical quality when smelting large ingots using complex alloy steels.

Study on the Characteristics of Molten Glass in a Float Glass Process with a New Structure.

Glass is one of the most common materials in society, and the float glass process is the main production method of glass used at present, which involves adopting a melting furnace with a single cooler. However, this structure has been difficult to fit to the requirements of modern glass production, such as producing multiple types of glass and large-scale production. Therefore, a large-tonnage float glass melting furnace with a double cooler is studied, which is rising in popularity in the glass sector. The aim of this paper is to clarify the characteristics of the new glass furnace. A numerical simulation technique is applied to analyze the thermal and flow characteristics of molten glass in the new structure so as to clarify the feasibility of production by checking the temperature distribution and flow field of the molten glass. The results show that the new structure also exhibits flow behavior similar to the original structure in the branch line. Due to the addition of the branch line, the stability of the temperature is improved, with a 60 K and 43 K difference between the surface and bottom in the main and branch lines, respectively. Similar stability is shown in the flow field, specifically low acceleration in the cooler (0.006 m/s2). The bubble clarification time is about 2700 s, less than the 3000 s required for flow. The parameters of the branch line meet the requirements of glass production. In theory, a glass-melting furnace with a double cooler has the capacity to produce two types of glass.

Numerical Simulation of Vanadium–Titanium Blast Furnace under Different Smelting Intensities

The blast furnace smelting of vanadium–titanium ore plays a crucial role in the efficient utilization of vanadium-titanium resources. In this research, a detailed numerical simulation study of the temperature, velocity, and concentration fields during the smelting process in a vanadium–titanium blast furnace was conducted. The actual production data from a 1750 m3 vanadium–titanium blast furnace was utilized, combined with softening and dripping parameters and material balance calculations, to develop a two-dimensional blast furnace model. This model was employed to analyze the effects of varying smelting intensities on the internal operating conditions of the furnace. The study found that as smelting intensity increased, significant changes occurred in the temperature fields and CO concentration fields within the furnace, thereby affecting the reduction efficiency of the burdens. Additionally, this research also shows that increasing the proportion of Baima pellets in the furnace will lead to the expansion of the soft melting zone and the upward movement of the soft melting zone. This investigation not only revealed the variations in the internal physical fields of the blast furnace under different operating conditions but also provided theoretical foundations and references for optimizing the design and operation of vanadium–titanium blast furnaces. By comparing the velocity field under different smelting intensities, it was found that the difference was small, which was mainly related to the expansion behavior of the pellets. These findings provide an important scientific basis for further improving the efficiency of blast furnace smelting and reducing costs.

Study on the effect of temperature on the microstructure and mechanical properties of as-cast CoCr2Ni3.5VAl1.5Ti high-entropy alloy

This study investigates the microstructure and mechanical properties of a CoCr2Ni3.5VAl1.5Ti high entropy alloy (HEA) annealed at 500 °C, 700 °C, 900 °C and 1100 °C for 6 h. The alloy was prepared using a vacuum induction melting furnace and annealed at the specified temperatures for 6 h. It was then characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron backscatter diffraction (EBSD). The results indicate that with increasing annealing temperature, the alloy's phase structure transitions gradually from multiphase (fcc, bcc, hcp) to predominantly fcc phase, with relatively stable elemental distributions. Annealing at 500 °C–900 °C mainly strengthens the alloy through precipitates and dislocation strengthening, whereas at 1100 °C, strengthening occurs through grain boundary strengthening and precipitate growth, enhancing the material's strength and ductility. The alloy exhibits optimal comprehensive performance after annealing at 1100 °C. This study provides important insights for optimizing the heat treatment process of HEAs.

Effects of Pressure on Nitrogen Content and Solidification Structure during Pressurized Electroslag Remelting Process with Composite Electrode

The nitrogen content and solidification structure of the 1Mn18Cr18N ingots produced by the customized laboratory‐scale vacuum induction melting furnace and the pressure electroslag remelting furnace (PESR) with novel composite electrode under different pressure and the same power consumption are compared and studied. The results show that there are perfectly uniform radial chromium and nitrogen profiles during the PESR process. The nitrogen uptake reaction in the PESR process with composite electrode takes place on the liquid metal film on the electrode. Nitrogen uptake could be improved by increasing the nitrogen partial pressure. In addition, the basin depth at a pressure of 0.1 and 1.22 MPa is about 41 and 38 mm, the angle of the grains with respect to the vertical axis is 35° and 31°, respectively. The flat metal basin profile resulted from the thermal resistance at the slag–mold interface decreasing with increasing pressure. Primary and secondary dendritic arm spacing (PDAS and SDAS) variations exhibit an increasing and subsequently decreasing the trend as they move further away from the center in a horizontal direction. Both PDAS and SDAS decrease with increasing pressure from 0.1 to 1.22 MPa.

Prediction of stable structure and unique charge transfer in Li–Pt intermetallic compounds under pressure

The exploration of new intermetallic compounds is of great significance for basic research and practical application. There is a huge electronegativity difference between Li and Pt, and the metals exhibit interesting and diverse properties; however, the structural behavior of Li–Pt intermetallics with different ratios under high pressure has not been systematically studied. In this study, an intelligent structure search method based on a particle swarm optimization algorithm combined with first-principles calculations was used to extensively explore the stable structures and unique conditions governing charge transfer in Li–Pt intermetallic compounds under different pressures. In addition to reproducing the known LiPt (P6‾m2) and Li2Pt (P6/mmm), the simulation was consistent with the experimental results. New phases were also found by calculation: LiPt3(Cmmm), Li2Pt (P3‾m1), and Li4Pt (I4/m) at ambient pressure; Li3Pt (Fm3‾m), Li4Pt (R3‾m), and Li5Pt (P6/mmm) at 10 GPa; and Li5Pt (P3‾m1) at 20 GPa. Bader charge analysis and electron localization function (ELF) mapping showed that the transition metal (Pt) atoms exhibit unusual oxidation states both under ambient and high pressure, and more electrons were localized on Pt as the Li content increased. The highest negative valence state was approximately −4. Intermetallic compounds LiPt3 (Cmmm) and Li2Pt (P6/mmm) were prepared successfully by arc melting furnace. The reliability of structure prediction method and pseudo potential selection was verified. This work demonstrates that tuning the pressure and stoichiometry is an effective means of forming novel, stable intermetallic compounds.

Quality Assessment of Aluminum Alloys for Automotive Rims

Abstract This paper presents experimental research conducted at a factory specializing in the development of aluminum alloys and the semi-continuous production of bars intended for rim manufacturing. The semi-finished products are made of 6082 aluminum alloy and undergo forging processes to obtain rims. The charge load consists of various types of aluminum waste and primary aluminum in different proportions, depending on the quality of the waste in the experimental recipes. The elaboration of the aluminum alloy takes place in melting furnaces with a capacity of 80 tons, equipped with two chambers. The casting is performed using a semi-continuous casting installation, and the cast semi-finished products undergo further heat treatment. The casting process involves the addition of alloying elements, in the form of wire, which serve to refine the structure. Experimental data were processed, and correlations between the qualitative characteristics of the alloy and the elements in the chemical composition, as well as grain size, were analyzed. From the obtained correlation analysis, it is observed that the alloying elements refine the grain size, while the grain size and quality of the resulting product are of interest for industrial practice.

Thermodynamic analysis of interactions between the components of the charge during the production of metallurgical silicon

The theoretical foundations of the recovery process and the technology of silicon smelting in electric arc furnaces are considered. The results of a study of thermodynamics, reaction kinetics, and mechanisms of the melting process are presented. Production issues are covered: charge preparation, smelting, refining, gas purification. Physicochemical models of the carbothermal process were developed, proposed and tested under industrial conditions (Tau-Ken-Temir LLP), which made it possible to assess the influence of the specified technological parameters of the smelting (chemical composition and loading coefficients of charge components, temperature) on silicon recovery and grade. To obtain the base material, metallurgical grade silicon is used, obtained by melting in ore-thermal furnaces (RTP). In this regard, the research goal is determined, which consists in studying ways to improve the quality (chemical purity) of silicon, and methods for achieving it at this stage of the study - modeling the carbothermal process for producing silicon.The article describes the main mechanism for the recovery of silica in the furnace, presents one of the designs of the furnace and the technological scheme for the production of silicon. The author suggested studying the process of producing metallurgical silicon in RTP using the HSC Chemistry software package. A model of silicon smelting in RTP was formed, which adequately describes the technological process for producing metallurgical silicon.

Addressing multi-step inverse heat transfer problems via reduced order models in a cooling process for polymer pipes with sparse measurements

In modern polymer pipe extrusion processes with connected post-processing steps, the intermediate cooling and conditioning process is essential for the resulting product quality. In such cases, computationally efficient models are required for real-time process control and optimization. Unfortunately, heat transfer coefficients are rarely known for actual production processes, leading to an inverse heat transfer problem. Existing methods mainly rely on computationally intensive numerical models or on data intensive neural networks. Both are not suitable, if only sparse measurements are available and a fast execution time is required. In contrast to that, we propose to use a proper orthogonal decomposition and project the governing heat equation onto extracted basis functions via the Galerkin method. This leads to an efficient and accurate reduced order model, which can be used for parameter identification and subsequent process control. Regarding the identification, we address the ill-posed problem with well-known relative constraints, l2 regularization and decomposition of coefficients based on the Nusselt number. Simulation and experimental results show that the heat transfer coefficients are consistently identified and robust against initial parameter guesses despite sparse and noisy temperature measurements. Consequently, the proposed method can be efficiently applied in cooling and conditioning processes in polymer extrusion and related applications such as identifying the heat transfer coefficients and thermal resistance in pressurized surge lines of nuclear power plants and brick walls in melting furnaces respectively.

Promising areas of slag processing in ferrous metallurgy

The characteristics of promising areas of slag processing in ferrous metallurgy are given. An increase in requirements for environmental protection was noted. Modern slag processing includes primary and secondary processing, which differ in the physical state of the slag. The technological foundations of mass processing of slag have been formed at the Ural Institute of Metals. An assessment of the state of slag processing shows that the capacity of crushing and screening plants, mainly due to complexes purchased abroad, exceeds the yield of slag of current production and leads to a decrease in dumps. Modern areas of economics and environmental protection require the creation and implementation of new technologies and equipment for the processing of slag in liquid and solid form, improving the quality of products at all stages of processing. Processing of slag in liquid form at furnace (or located near melting furnaces) plants will make it possible to organize the technological process in highly economical environmentally friendly small-sized units, to adjust the composition and properties of slag, to expand the range and quality of the resulting products, to create conditions for the utilization of melt heat and the recycling of slag processing products. These processes reduce the environmental burden on the environment, reduce material, energy and operational costs, and expand the range and quality of the products obtained

Sensor self-diagnosis method for a nickel top-blowing furnace based on graph interactive dynamic fusion

Abstract As modern industry gradually advances towards greater automation and intelligence, the scale of nickel top-blowing furnace smelting systems is continuously expanding, leading to an increasing need for sensor maintenance. Traditional periodic evaluations and manual maintenance methods are no longer sufficient to meet the development needs of intelligent sensors. To address this issue, this paper proposes a sensor self-diagnosis method based on graph interactive dynamic fusion, called DLGCN-GIDF. First, a combination of knowledge-driven and data-driven approaches is introduced. By constructing a dual-layer architecture based on a functional module graph network and a sensor graph network, a sensor correlation graph model for the nickel top-blowing furnace system is established. Next, with the aid of a GIDF module, the relative weights between functional modules and sensors are integrated to perform spatiotemporal correlation-based graph fusion. This enables the prediction of spatiotemporal data for sensors from a system perspective. Finally, the goal of sensor self-diagnosis is achieved using a standardised residual testing algorithm. Taking a nickel top-blowing furnace smelting system as an example, the feasibility and effectiveness of our method of sensor fault self-diagnosis are verified.

Comparison of corrosion behavior of primary/modified nickel slag with semi‐rebonded periclase‐chromite refractory

AbstractSemi‐rebonded periclase‐chromite refractories are commonly utilized in the working lining section of the molten pool in oxygen‐enriched top‐blowing furnaces for nickel production. Its resistance to nickel slag corrosion determines the safety and service life of the melting furnace. The composition of nickel slag influences the corrosion resistance of semi‐rebonded periclase‐chromite refractories. By comparing and analyzing specimens corroded by primary and modified nickel slag, the influence mechanism of w(CaO)/w(SiO2) variations on corrosion resistance of semi‐rebonded periclase‐chromite refractories was clarified. The results show that a spinel isolation layer is preferred to form at a lower w(CaO)/w(SiO2) ratio (< 0.576) and enhance the corrosion resistance of semi‐rebonded periclase‐chromite refractories. As the ratio increases, the slag viscosity falls and the corrosion products contain larger levels of Ca3Cr2Si3O12 and Ca3MgSi2O8, which prevent the creation of the isolation layer and establish a conduit for Ca2+ and Si4+ transport and reaction into the interior of the refractory.

CFD–DEM modeling of particle segregation behavior in a simulated flash smelting furnace

Particle behavior plays a crucial role in flash smelting furnaces, but limited understanding is hindering further development of this modern pyrometallurgical process. This study presents a two-way coupled CFD–DEM approach to investigate particle distribution, collision, and segregation behaviors within a furnace. The simulation results are validated against experimental data, demonstrating good agreement. The effects of the particle mass–flow rate and size distribution are then analyzed. The results indicate that small particles are carried by airflows to the center of the particle-dense region, whereas large particles remain at the outer part, worsening segregation. Increasing the mass–flow rate significantly increases the particle number density and number of particle collisions but barely influences size-induced segregation. In contrast, enlarging the size of fed particles reduces particle number density and broadens dense distribution within a safe range. This ensures the necessary space and high mixing index of the particles, which benefits high-rate smelting processes.