In this study, a laboratory-scale slag–steel reaction experiment was conducted to systematically evaluate the influence of the initial MgO content (3–7 wt.%) in LF refining slag on the cleanliness of GCr15 bearing steel. The assessment was performed from multiple perspectives by comparing the total oxygen content (T[O]) in molten steel, the inclusion area fraction, and the inclusion number density after 30 min of slag–steel interaction. To further elucidate the thermodynamic driving forces and kinetic mechanisms governing inclusion capture by slag, a predictive slag adsorption model was developed using an in-house computational code coupled with FactSage 8.1. Under conditions of slag basicity R (CaO/SiO2) ranging from 4.0 to 8.0, MgO content varying from 0 to 7 wt.%, and a constant Al2O3 content of 32 wt.%, the chemical driving force ΔC (the mass-fraction difference between slag components and inclusions), the slag viscosity η, and the combined parameter ΔC/η were calculated at 1600 °C for three representative inclusion types: Al2O3, MgO·Al2O3, and MgO. In addition, the model was employed to quantitatively characterize the adsorption capacity of slag toward Mg–Al binary inclusions under varying MgO levels. Both experimental observations and model calculations demonstrate that the slag–steel reaction markedly enhances inclusion removal, as evidenced by pronounced decreases in T[O], inclusion number density, and inclusion area fraction after reaction. With increasing MgO content in slag, T[O] and inclusion-related indices exhibit a consistent trend of first decreasing and then increasing, reaching minimum values at an MgO level of 5 wt.%. Further analysis reveals a positive correlation between the apparent inclusion-removal rate constant ko and ΔC/η corresponding to MgO·Al2O3 inclusions. Moreover, the slag’s adsorption capacity toward Mg–Al binary inclusions decreases overall as the MgO fraction in inclusions increases. Notably, when the MgO content in inclusions exceeds 29 wt.%, the adsorption capacity undergoes an abrupt drop, indicating a pronounced cliff-like attenuation behavior.

Numerical simulation of gas quenching process for molten steel slag based on VOF to DPM model

Numerical investigation of waste heat recovery and process safety enhancement in molten steel slag granulation by CO2 quenching: Mechanisms, optimization and industrial implications

Dependency of collision phenomenon of inclusions on surface of molten steel on intermolecular force

Based on the process parameters of bottom argon blowing in the steel ladles of a certain steel plant, a 1:1 full-scale numerical model was established. The evolution laws of the flow field structure, homogenisation characteristics, and fluctuation behaviours of the steel and slag interfaces under different blowing rates were analysed in detail. The mechanism of the effects of different blowing parameters on the flow characteristics of the molten material and metallurgical efficiency was clarified. Research indicates that a double plug, different flow bottom blowing model can effectively reconfigure the melt pool flow field structure by differentially regulating the gas supply parameters of the porous plug. The upward flow created by the high bottom blowing rate (800 L/min) has stronger penetration, driving the molten steel to form a high-level diffusion circulation; the low bottom blowing rate (400 L/min) forms a diffuse flow field near the bottom. Together, they create a three-dimensional circulation system that covers the entire area. Numerical simulations and water model experiments confirm that the 800_400 L/min mode exhibits optimal dynamic characteristics: the mixing time calculated numerically is controlled within 47 seconds, a 5% reduction compared to the original mode. Additionally, the overall fluctuation of slag in the 800_400 L/min mode is controlled within 0.25 m, a 17% reduction compared to the original mode. Notably, this mode achieves a 25% reduction in argon gas consumption while maintaining metallurgical effectiveness, demonstrating significant engineering and economic benefits, and also providing a theoretical basis for optimising the refining process.

High-performance Al2O3-MgAl2O4-C ceramic filters for molten steel filtration: A comparative study with Al2O3-C, ZrO2 and SiC ceramic filters

Mechanism and Effect of Carbon–Oxygen Reaction on Nitrogen Content in Molten Steel During BOF Process

Numerical Simulation of Molten Steel Flow and Ladle Filler Sand Removal in Tundish During Ladle Changeover Process

ABSTRACT Exploring the flow characteristics of the molten bath during the blowing process with oxygen lance nozzles at different wear levels can optimise the converter smelting operation. In this study, a nozzle jet impact molten bath model was established to represent molten bath behaviour throughout the nozzle’s service life (varying degrees of wear). The evolution of velocity distribution, dead zone volume, and turbulent kinetic energy in the molten bath under different nozzle wear conditions was systematically studied. Meanwhile, key indicators of the industrial smelting process were statistically analyzed. The results show that as the wear degree of the oxygen lance increases, the average dynamic pressure in the molten bath and the uniformity of the jet-stirred molten bath gradually decreases. While the volume of dead zones progressively increases – by up to 13.69%. Industrial smelting data indicate that with increasing heat numbers, key process parameters – such as oxygen consumption, FeO content in slag, and the carbon–oxygen product ([C]·[O]) in molten steel – exhibit an upward trend. By the end of the nozzle’s service life, oxygen consumption increased by 13.22%, FeO content by 1.2%, and [C]·[O] in 0.04 wt.%C molten steel by 12.61%.

Enhancing the Degassing Efficiency of Molten Steel in Vacuum Casting via Vacuum Control

Electrochemical experiments were carried out to monitor the variations of open voltage with time during the aluminium (Al) deoxidation process for iron melt with additional Al amounts in the range of 0.01%–2.0% at the temperature of 1873 K. Thermodynamic parameters, Fick’s second law and a reaction kinetic model were used to calculate the equilibrium oxygen contents (EOCs) at the iron melt–solid electrolyte interface, reaction order and rate-limited step in the current conditions. The results show that the EOCs at the interface show a trend of decreasing first and then increasing with the increase of additional Al amounts. The turning point of the EOC change, that is, the lowest value of EOCs, corresponds to and addition Al amount of 0.5%. The reason for the appearance of the EOC turning point is that the activity coefficient of oxygen decreases with Al addition, increasing from 0.01% to 2.0%. Kinetic analysis indicates that the reaction order of an Al deoxidation reaction with 0.01% Al addition is 8. Orders 1 and 2 correspond to different stages of the Al deoxidation reaction with 0.50% Al addition. The reaction orders are all 1 for 1.0%–2.0% Al addition. The diffusion coefficient of oxygen fitted by Fick’s second law is 1.47 × 10 −6 –2.10 × 10 −5 cm 2 /s in molten steel with Al additions of 0.01%–2.0%. When the Al addition is 0.01%–0.50%, the rate-determining step of the Al deoxidation reaction is Al 2 O 3 formation and oxygen diffusion in the melt. When the Al addition is 1.0%–2.0%, the rate-determining step of the Al deoxidation reaction is the decomposition reaction of Al 2 O 3 and the diffusion of oxygen in the melt.

The flow and solidification inside the mould are crucial to the quality of the casting billet during continuous casting. In this work, a three-dimensional coupled model of flow and solidification was established, and the flow field and temperature distribution characteristics of molten steel were deeply explored. The results indicated that the molten steel streams out of the SEN at a defined degree and enters the mould in the form of an impact stream, and then impacts the narrow surface. The eddy core position in the upper recirculation region of the flow field is (0.565 m, −0.179 m), and eddy core position in the lower recirculation region is (0.524 m, −0.455 m). Within the range of 100–400 mm from the liquid surface, the main stream and upper ring flow of molten steel have a significant impact on the solidification of the casting billet, and the distribution and longitudinal variation in the liquid phase ratio at different height sections are very obvious. At the exit of the mould, the average thickness of the inner arc and outer arc shells is 15.2 mm and 14.5 mm, respectively. The model can provide guidance for enhancing and optimizing the quality of continuous casting billets.

Ladle furnace (LF) refining is one of the most widely used secondary refining processes for producing clean steel and constitutes a key process in the steelmaking–continuous casting section. The properties of slag play a decisive role in determining molten steel quality and refining efficiency. In this study, based on the composition of refining slag from a steelmaking plant in China, the properties of a CaO-SiO2-MgO-Al2O3 slag system were investigated with respect to five aspects, the liquid phase region, sulphide capacity, melting properties, slag viscosity, and mineralogical phase precipitation, at varying temperatures, basicity, w(MgO) and w(Al2O3) using FactSage and the KTH model. Analysis of the slag properties indicates that the CaO-SiO2-MgO-Al2O3 slag system performs better when basicity ranges from 3 to 4, w(MgO) is between 6% and 8%, and w(Al2O3) is 15%–25%. These findings provide theoretical support and guidance for optimizing the refining slag system in plant trials.

The flow and heat transfer inside the mold play an important role in the quality of the casting billet during continuous casting. In this work, a three-dimensional coupled model of flow and heat transfer was established, and the flow field and temperature distribution characteristics of molten steel were explored in depth. The results indicated that the narrow impact position is 315 mm away from the meniscus. The maximum turbulence kinetic energy of the centerline reached 0.00284 m2∙s−2, 108 mm from the narrow surface. The temperature of the steel liquid on the path of the two splitting strands located in the upper and lower circulation zones was above 1781 K. The temperature range from the center of the billet to the narrow 1/4 section, which was enclosed by the upper annular flow zone and 400 mm below the liquid level, was relatively low and lower than the liquidus temperature. The model can provide guidance for improving and optimizing the quality of continuous casting billets.

Revealing interfacial properties and agglomeration characteristic of rare earth aluminate inclusion in molten steel

Effect of microporous Al2O3–MgAl2O4 content on the thermal shock resistance and molten steel purification performance of β-SiC whisker-reinforced Al2O3–MgAl2O4–C ceramic filters

Discarded NdFeB permanent magnets will become a significant source of rare earth elements (REEs) in the future. Electric vehicle (EV) motors utilize 2–5 kg of NdFeB magnets, and researchers are prioritizing the development of suitable extraction technologies. The objective of our research is to separate metal materials (Al, Cu, Fe and FEEs) from EV motors, based on their melting temperatures. REE magnets that pose the greatest challenge are melted together with the electrical steel of the motor, and the potential for extracting REEs in a selective manner from the molten steel was examined based on their significant oxidation potential using FeO–SiO2 compounds, which act as an oxidizing slag-forming agent, to test the extraction method. Fayalite (2FeO·SiO2) is the most easily created and ideal eutectic compound for carrying oxygen (FeO) and forming slag (SiO44−), typically generated during copper smelting. In this experiment, copper slag was used and the results were compared to a smelting test, which had previously used a synthesized fayalite flux as a model. The smelting test, utilizing synthesized fayalite flux, yielded a 91% Nd recovery rate. The Nd recovery rate in the smelting test with copper slag hit a high of 64.81%, influenced by the smelting’s holding time. The steel contained 0.08% Nd. Iron was recovered from the copper slag at a rate of 73%. During the smelting test, it was observed that the reaction between Nd2O3 and the Al2O3 crucible resulted in the formation of a layer on the surface of the crucible, diffusion into the crucible itself, and a subsequent reduction in the efficiency of Nd recovery.

ABSTRACT Saw wire steel, a high-cost, quality-determining solar wafer consumable, has seen surging demand with China’s booming photovoltaic industry. However, its ultra-fine diameter and higher strength than tire cord steel greatly increases inclusion sensitivity and subsequent wire breakage, creating an urgent need for better inclusion control. This study investigated the evolution mechanisms of inclusions during its refining and the effects of top slag composition on molten steel and inclusions, using simulated top slag experiments and FactSage thermodynamic calculations. It shows that only Al2O3 content in inclusions remains stable while other components vary significantly, which makes simulated steel-slag experiments only applicable for guiding Al2O3 control in industry production. Increasing basicity or Al2O3 in slag raises [Al]s content in steel, which in turn leads to an augmentation in the Al2O3 content within inclusions. As the Al2O3 content in the inclusions increases, the proportion of low-melting-point inclusions first rises and then falls. Additionally, the deformability of the inclusions shows a distinct positive correlation with the proportion of low-melting-point inclusions. Under laboratory conditions, maintaining a slag basicity of 1 and an Al2O3 content of approximately 2% results in refined inclusions that exhibit the lowest melting points and optimal deformability.

Herein, a coupled three‐dimensional large eddy simulation model and volume of fluid model is established to systematically investigate the effect of the argon injection through single‐channel and multi‐channel stopper rods, casting speed, and argon flow rate on the molten steel flow, spatial distribution of bubbles, and jet characteristics of a bifurcated submerged entry nozzle (SEN). The comparison with the water model shows that the current model can accurately predict the bubble distribution in the SEN. The multi‐channel argon blowing makes the argon distribution more uniform and generates bubbles with smaller diameters and larger quantities. The average diameter of bubbles is 16.72 mm in the single‐channel blowing, while the average diameter of bubbles is 12.03 mm in the multi‐channel blowing. The dispersion degree of argon bubbles increases with the increase of casting speed. The jet speed and backflow speed increase with the increase of the casting speed, while the jet vertical angle and the proportion of the backflow zone decrease gradually. With the increase of the argon flow rate, the fluctuation of the backflow speed at the outport will also increase. The injection of argon has a significant impact on the jet characteristics at the outport.

The steel industry is responsible for 7–9% of global CO2 emissions. Shifting from primary iron ore to recycled scrap in electric arc furnace (EAF) steelmaking offers significant decarbonization potential, reducing carbon intensity by 60–70%. However, increased scrap use in EAF operations leads to higher nitrogen absorption, which can degrade mechanical properties. Nitrogen dissolves into molten steel, where it forms Cottrell atmospheres at dislocations in the following processing steps, intensifying strain aging and reducing ductility. This study establishes a precipitation criterion based on the TiN solubility product to prevent harmful liquid TiN formation, enabling effective nitrogen fixation via fine TiN precipitates (5–20 nm). Multiscale characterization techniques, such as TEM and EBSD, show that Ti reduces the number of mobile N atoms by 60–70%, evidenced by a 50–65% decrease in Snoek/SKK peak intensities. Excessive titanium can refine ferrite grain size and prevents harmful TiN inclusions. Titanium microalloying presents a cost-effective, sustainable strategy to reduce strain aging in scrap-rich EAF steels, enabling more sustainable steel production without sacrificing material properties.