Vanadium-titanium magnetite boasts a formidable storage capacity within China, particularly illustrated by the Hongge ore, amounting to an astounding 1.829 billion tons ripe for extraction. Nevertheless, the intricate mineral composition of the Hongge ore, which exhibits an extraordinary concentration of Cr₂O₃, presents significant challenges for its effective utilization. To date, only preliminary explorations have been undertaken on the Hongge ore, and investigations into its ore phase composition, as well as the processes of beneficiation and smelting, remain decidedly limited. This study undertakes a theoretical and experimental investigation of the viscous flow characteristics of the CaO–SiO₂–MgO–TiO₂–Al₂O₃–Cr₂O₃ slag system, seeking to elucidate the impact of basicity on the viscous properties of the slag derived from Hongge ore. As the basicity increases, the slag’s viscosity decreases, the activation energy for viscous flow initially increases and then decreases, while its melting temperature exhibits an upward trend. It is recommended that, when the Hongge ore is utilized as metallurgical raw material, the slag’s basicity should not surpass 1.10.

In a continuous casting process, the clogging of the immersion nozzle with inclusions occurs as a result of the adhesion, agglomeration, and coalescence of inclusions. The most effective way to understand the behavior of inclusions, i.e. oxide particles, in a liquid steel is the in-situ observation. To our knowledge, however, there is no research on the in-situ observation of the behavior of oxide particles in a liquid steel. In the present work, therefore, the in-situ observation method for sintering interface between Al₂O₃ particle/single crystalline Al₂O₃ plate by laser microscope through single crystalline Al₂O₃ plate is proposed. First, the in-situ observation of sintering interface between Al₂O₃ particle and single crystalline Al₂O₃ in Ar atmosphere is conducted to verify the observation method for the interface through single crystalline Al₂O₃ plate. Then, the in-situ observation of sintering interface between Al₂O₃ particle and single crystalline Al₂O₃ in a liquid Ag is challenged. The observations for sintering interface between Al₂O₃ particle and single crystalline Al₂O₃ plate in Ar gas atmosphere and a liquid Ag are achieved by our proposed method. It is verified that the growth of sintering interface in liquid Ag is faster than that in an Ar gas atmosphere. This finding indicates that the non-wetting by liquid Ag of alumina particles promotes the growth of sintering interface in liquid Ag.

In the course of industrial electroslag remelting (ESR), large-size Ca–Al–Mg–O nonmetallic inclusions were prone to form in 4Cr13 die steels and will deteriorate mechanical properties and service life seriously. In order to reveal the underlying mechanism, this work delves into the origins of Ca–Al–Mg–O inclusions in 4Cr13 die steel, establishing a correlation between inclusion characteristics and ESR slag composition. Utilizing molecular dynamics simulations, this work examines the CaO–Al₂O₃–CaF₂–SiO₂–MgO slag system, analyzing slag microstructure and the mean square displacement of Ca²⁺ ions. Combining the ion and molecule coexistence theory (IMCT), it was demonstrated that the key factor determining the total calcium (T.Ca) content and large-size Ca–Al–Mg–O inclusions in ESR steel is the concentration of free Ca²⁺ ions in the slag. In addition, a model for calculating free Ca²⁺ ions concentration in slag has been formulated based on IMCT. This model elucidates the influence of CaF₂ and CaO on the concentration of free Ca²⁺ ions in slag. The empirical data facilitated the development of a modified slag composition with reduced CaF₂ content, aiming to lower the T.Ca content in steel and reduce the quantity and size of Ca–Al–Mg–O inclusions. These hypotheses have been verified through a series of laboratory and industrial trials. This is crucial for optimizing the ESR slag composition and enhancing the metallurgical quality of ESR steels.

The three-dimensional pore structure and strength characteristics of two types of coke, Coke CC (produced from caking coal) and Coke LC (produced from low-quality coal), were assessed employing the maximal ball (MB) method and the finite element method (FEM). The MB analysis showed that Coke LC demonstrated larger and more connected pores, characterized by a higher coordination number, indicating greater pore connectivity. The FEM stress analysis showed that Coke LC displayed a less uniform matrix, leading to localized stress concentrations and increased anisotropy in the elastic modulus. These findings indicate that the lower drum strength of Coke LC is because of its nonuniform pore structure and higher susceptibility to stress concentration. Multiple regression analysis confirmed that pore connectivity, quantified by the coordination number, significantly impacts coke strength, with higher coordination numbers (greater than 8) being associated with increased elastic modulus. These results underscore the importance of a uniform, highly interconnected pore structure in enhancing coke strength, offering valuable insights for optimizing coke production to improve its mechanical properties.

The effective management and utilization of bauxite residue poses a significant challenge for the alumina industry, especially given the escalating demand for aluminum. This investigation focuses on utilization of bauxite residue to produce high-purity iron and the creation of leachable calcium aluminate slag through processes involving hydrogen reduction and smelting. Bauxite residue was pelletized and then underwent reduction at 1000°C in the presence of hydrogen. The resulting reduced bauxite residue was subsequently milled and blended with varying percentages of CaO, followed by smelting at 1500°C to recover iron and a leachable calcium aluminate slag. Analytical techniques such as X-ray diffraction, Electron Probe Microanalysis, scanning electron microscopy, and X-ray fluorescence were employed to assess the phases, microstructure, and chemical compositions. The hydrogen reduction process successfully transformed iron oxide in the bauxite residue into metallic iron. The increasing amounts of CaO in smelting led to the dominance of the calcium aluminate (CaO·Al₂O₃) phase in the slag products, with the phase composition remaining relatively stable after reaching a 40% CaO content. Key phases identified in the smelted slag included CaO·Al₂O₃, Ca₂Al₂SiO₇, and CaTiO₃. Notably, the iron produced during smelting exhibited a purity exceeding 99.5%, comparable to electrolytic iron. Experimental analysis revealed a positive correlation between the purity of iron and the concentration of CaO in the slag melt. Only a minimal amount of iron, primarily in the form of FeO, was observed in the slag, a phenomenon corroborated by FactSage analysis.

This study investigates the effects of varying Al₂O₃ content in sinter on the softening-melting behavior, permeability, and slag characteristics of blast furnaces under hydrogen-injection conditions. Through softening-melting experiments of burden, viscosity and wetting testing of the slag. The results indicate that the increase in Al₂O₃ content first expands and then narrows both the softening and melting intervals. The addition of hydrogen significantly improves the permeability of the burden, attributed to the small molecular size of hydrogen and its influence on the slag composition. As Al₂O₃ content increases, the permeability of burden is improved due to liquid phase of the slag increases, the viscosity of the solid-liquid mixture decreases, and the wettability of the slag with coke decreases. When Al₂O₃ content of 2.48 wt% in sinter exhibits optimal permeability due to its low melting temperature and good fluidity of the slag. Overall, in gas-injection blast furnaces, high Al₂O₃ content in the burden results in a larger slag volume at elevated temperatures, lower viscosity of the solid-liquid mixture, and poor wettability with coke, which stabilizing the deterioration of permeability.

To reduce the production costs of ultra-low carbon steel, an oxygen lance has been employed in a 150 t decarburization ladle furnace. This study conducted both water experiments and numerical simulations to examine the flow field characteristics and stirring effects of the top-blowing lance at various inclination angles of 4°, 6°, 8°, and 10°. The results indicated that a smaller inclination angle enhanced the mixing effect and impaction depth of the molten bath, whereas the impaction diameter exhibited a contrasting trend. The behavior of the oxygen multi-jets suggested that a smaller inclination angle mitigated the loss of kinetic energy, thereby improving impaction ability. As the depth of the molten bath increased, the average velocity of the molten bath section displayed a trend characterized by an initial rapid decrease, followed by a gradual decline, and culminating in a subsequent rapid drop. In industrial application research, the 4° oxygen lance resulted in a shorter decarburization time compared to the 8° oxygen lance. This reduction in decarburization time led to decreased heat energy loss due to the heat-absorbing effect of ambient gas, which further enhanced the end-point temperature of the molten bath.

A two-dimensional bubble coalescence model of the desulfurization bubble group in the magnesium injection method during the rising process was established in this study. The Volume of Fluid (VOF) method accurately captures topological changes at the gas-liquid interface and the behavior of bubble jets. Additionally, it represents the splash behavior of molten iron through the gas-liquid flow field structure, bubble jet phenomena, liquid level fluctuation differences (h_f), and splash heights (h_S). The findings reveal that vertical, horizontal-vertical, and Z-shaped bubble groups exhibit two, one, and two coalescence events, respectively. The coalescence process is driven by the butterfly wake vortex. The liquid level fluctuation difference for the vertical bubble group reaches 8.53 mm, while the splash height measures 0.062 m. For the horizontal-vertical and Z types, these values are 9.11 mm, 0.059 m and 15.28 mm, 0.06 m, separately. The disturbance caused by bubbles after coalescence significantly affects the liquid surface more than bubbles that do not coalesce. Furthermore, bubble breakup at the interface exacerbates the splashing behavior of molten iron. Ultimately, the results confirm that altering the spray gun’s position and injection frequency can change the rising behavior of bubble groups, thereby reducing the splashing of molten iron.

The main function of the tundish is to constantly provide molten steel to each strand, for which it is important to determine the uniformity of residence times, particularly in multiple-strand tundishes. In this study, the residence time distribution, minimum and maximum concentrations, and active and dead volume fractions were determined in a 5-strands asymmetric tundish equipped with turbulence inhibitors and argon curtains. Physical modelling was used as a tool, for which a 1:3 reduced-scale analogous water model of the prototype tundish was designed and constructed. For the experimental analysis four cases were studied, the stimulus-response technique was used, in which an inert tracer (HCl) was injected as a pulse at the ladle shroud, the change in the water conductivity was measured at each of the strands, the minimum residence times and the times at which the concentration was maximum were measured and recorded, and the residence time distribution (RTD) curves were plotted; a mixed model was used to characterize the active flow volume fractions (piston and mixed) and dead volume fraction. From the analysis and discussion of the results, no uniformity was observed in any of the four cases studied for the maximum concentration time. The hexagonal turbulence inhibitor alone achieved a result very similar to that of the arrangements with argon diffuser in their characteristics and flow distribution. The use of argon diffusers is recommended to improve the cleanliness of steel.

As a representative of high-speed wire, cord steel has the advantages of high strength, high toughness and so on, and is widely used in transportation and other industries. Decarburization layer is one of the key factors affecting the quality of cord steel products. Excessive thickness of decarburized layer leads to the decrease of fatigue strength and wear resistance of the material, which affects the service life and performance stability of the product. The decarburization process is affected by many factors such as heating temperature, holding time, and the interaction between the factors makes the thickness of the decarburization layer difficult to be accurately controlled. In this paper, an online prediction model of decarburization layer based on functional kernel Fisher discriminant analysis (FKFDA) method is constructed, and an extended Morris screening method is proposed. First, scalar data and multivariable time series data are combined, and then a nonlinear classification model is constructed using FKFDA to establish the corresponding relationship between heterogeneous production data and actual decarburization layer. Then, the proposed FKFDA method is applied to the actual cord steel production dataset. The accuracy of the proposed method is 75.6%, and the G-mean value is 0.722 on the cord steel production dataset, which has higher prediction accuracy than other methods. Finally, the extended Morris method based on the curve shape change is proposed to get the key factors affecting the decarburization layer, and the results are consistent with the actual situation.

The development of ultrafine grained microstructures under severe plastic deformation by burnishing process was investigated using spherical cementite-ferrite (SA) steel and pearlite (P) steel of AISI 52100. Microstructures were analyzed using FE-SEM, FE-TEM and EBSD observations. In the SA steel, equiaxed ultrafine ferrite grains were formed at the burnished surface where the equivalent strain was about 3.9. These ultrafine grains were formed by continuous dynamic recrystallization because they consisted of high angle grain boundaries. On the other hand, in the P steel, the initial lamellar structure was maintained even at the equivalent strain about 4.3, and ferrite grains with a large aspect ratio were formed. These ferrite grains were considered to be non-recrystallized grains because the KAM value within these grains was high. In addition, many dislocation contrasts in the same direction were observed within a ferrite grain by FE-TEM observation. These results suggested that active dislocation slip system in these ferrite grains is limited by lamellar structure. As the strain increased by repeated burnishing process, these ferrite grains of P steel became coarse and the KAM value within these grains decreased. In addition, several dislocation contrasts in multiple directions were observed within a ferrite grain. It can be concluded that the limitation of active dislocation slip system in these ferrite grains were relaxed, and dynamic recovery was occurred in these ferrite grains.

We systematically investigated changes in crystal orientation due to the cold rolling of a {110}<110> single crystal, which had not been researched to date, in a reduction range of 10–70%. The results allowed for a classification of the changes into the following three reduction cases. The first was a 10–20% reduction. For this reduction, there was almost no change in the matrix orientation, and a shear band slightly appeared near the surface layer. The second was a 30–50% reduction, at which many shear bands were introduced, and the crystal orientation inside the shear bands was rotated from the initial {110}<110> orientation to the {100}<001> orientation around the TD axis. There are cells in the shear band. And {100}<001> orientation cells are considered having lower strain than around cells to having lower GAM. Additionally, the {111}<211> orientation was also confirmed in a small area that was thought to be surrounded by shear bands. The third was a 60–70% reduction, at which the matrix rotated to {111}<110>, but there were some areas with a {111}<211> orientation. Furthermore, the shear bands increased with increasing reduction, and more inner orientations were observed for {111}<211> than for {100}<001>. {111}<211> bands and {100}<001> bands are considered different origins to change discontinuously.

Titanium-bearing blast furnace slag (TBFS), a byproduct of ironmaking processes, has long been discarded as waste, resulting in the squandering of valuable resources such as titanium. The recovery and effective utilization of TBFS hold immense significance and importance. This study reports a direct electrolysis method for synthesizing Ti₅Si₃ alloy from a TBFS/SiO₂ mixture in molten CaCl₂ at 950°C. A comprehensive investigation was conducted into the phase and morphological evolution during the electrolysis process, along with an analysis of the migration behavior of impurities such as Ca and Al present in TBFS. The synthesized Ti₅Si₃ alloy powder was systematically characterized and analyzed using scanning electron microscopy, transmission electron microscopy, and other techniques. The results reveal that the electrolysis process encompasses electrochemical deoxidation, in-situ alloying, and self-purification. Furthermore, this study achieved further purification of the Ti₅Si₃ alloy through vacuum laser rapid melting, effectively volatilizing and removing the residual impurity elements, resulting in an increase in the purity of Ti₅Si₃ alloy from 96.8% to 98.6%. The resultant Ti₅Si₃ alloy exhibits excellent corrosion resistance in phosphate buffer solution. In summary, this work provides a crucial technical paradigm and scientific theoretical foundation for the resourceful and value-added utilization of ironmaking solid waste, specifically TBFS.