This study investigates the interfacial reaction between high-Mn high-Al steel and refining slag in gas-stirred ladles. An uncoupled model was established by integrating computational fluid dynamics (CFD) with the effective equilibrium reaction zone (EERZ) theory. By analyzing the transient characteristics of the slag–steel interface under varying argon blowing conditions, the effects of initial Al content, plug configuration, and slag composition on desulfurization efficiency and steel cleanliness were elucidated. The results indicate that the slag eye area expands with increasing argon flow rates. However, a single-plug configuration exhibits an inflection point at 250 NL/min, where the expansion rate drops to 41 pct of its initial value. A critical flow rate exists between 250 and 500 NL/min: a single-plug setup yields a larger slag eye at low flow rates, whereas the dual-plug configuration dominates at high flow rates. While dual-plug operation markedly promotes interfacial mass transfer, flow rates above 500 NL/min induce severe interfacial instability. N pickup via the slag eye is the primary mechanism at 1 wt pct Al, whereas AlN precipitates when Al exceeds 5 wt pct. Higher Al content reduces Al2O3 formation and promotes MgO reduction, leading to a transition of inclusions toward AlN and MgAl2O4 spinel. The total amount of MgAl2O4 is optimized under low flow single-plug (100 NL/min) or high flow dual-plug (≥ 500 NL/min) conditions, whereas AlN suppression demands an opposing strategy. Higher CaO/Al2O3 or lower Al2O3/SiO2 ratios enhance desulfurization and accelerate the transition of Al2O3 into MgAl2O4, CaMg2Al16O27 and CaAl4O7. This effect tends to stabilize beyond a CaO/Al2O3 ratio of 1.0 or an Al2O3/SiO2 ratio of 3.8.
A 1:3-scale water model was established to investigate mold slag emulsification and entrainment in a continuous casting mold. Mold-level fluctuation, internal flow field evolution, and slag-phase morphology were characterized using wave height measurements, particle image velocimetry, and image-based quantitative analysis. The results show that slag emulsification proceeds through initial, stable, and complete stages, driven mainly by argon bubble motion and gas–water–slag interaction. Four entrainment modes were identified: shear-induced, vortex-induced, bubble breakup-induced, and emulsified suction-induced entrainment. Casting speed mainly intensified the submerged entry nozzle (SEN) jet, mold-level fluctuation, and shear near the slag layer, thereby markedly promoting slag entrainment; the number of entrainment events increased from 1 to 36, and the cumulative entrainment area increased from 0.65 to 47.51 cm2. Increasing gas flow rate significantly increased the emulsified slag layer thickness, while the entrainment area first increased and then decreased, peaking at 1.64 L/min. Increasing SEN immersion depth weakened near-surface turbulence and reduced mold-level fluctuation, causing the entrainment area to decrease continuously from 57.35 to 0.329 cm2, while the emulsified slag layer thickness increased and then stabilized. These findings clarify the coupled effects of operating parameters on slag emulsification and entrainment.
Oxide inclusions strongly influenced the deformation compatibility of tire cord steel during hot working. In this study, the composition, size, number, spatial distribution, and deformation (morphology and aspect ratio) of oxide inclusions were quantitatively characterized across the full thickness of the billet and the full diameter of the first-pass (1st) hot-rolled rod using an automated microscopy system. The spatial distribution of inclusions changed after hot rolling: the average SiO2 content of the detected inclusions increased from 56.8 to 65.7 wt pct, with SiO2-rich inclusions becoming more prevalent in the near-surface region of the 1st hot-rolled rod. The maximum number densities of SiO2-rich and SiO2–MnO–Al2O3 inclusions were 5.10 mm−2 in the near-surface region and 4.76 mm−2 in the central region of the hot-rolled rod, respectively. The rolling process elongated the inclusions along the rolling direction. The average equivalent-area diameter decreased from 3.07 to 2.70 μm, whereas the average aspect ratio increased from 1.56 to 8.71. Moreover, the highest average diameter and aspect ratio were consistently observed in the central region. The deformation behavior of inclusions was strongly associated with their high-temperature deformability, which depends on their melting temperature (Tm), viscosity (η940), flow stress, and internal phase constitution. Multicomponent silicate inclusions with low Tm (< 1550 °C) and low η940 (< 16.12 ln(Pa·s)) exhibited excellent deformability, with aspect ratios exceeding 10 in the center. In contrast, S-type inclusions, with high Tm (> 1670 °C), underwent almost no deformation and restricted the final deformation of SiO2–MnO inclusions, resulting in an average aspect ratio of only 6.82 in the center.
The high-value utilization of silicon wafer cutting waste (SWCW) as a ferroalloy is a key way to balance resource recycling and environmental management. However, the oxide layer (SiOx) of SWCW hinders direct Si recovery and can form non-metallic inclusions in Fe–Si–Ce alloy. To address this, we developed an integrated-melting route using composite CaO–Al2O3–MgO sintering aids, coupled with an alloying treatment that employs the Si core of SWCW as the Si source for the Fe–Si–Ce alloy. During low-temperature melting, the sintering aids react with SiOx to form a low-melting-point CaO–Al2O3–MgO–SiO2 melt that effectively dissolves the oxide layer of SWCW. MgO helps dissolve the oxide layer and reduces its aggregation, thereby enhancing fluidity and mass transfer. CeO2 further disrupts the slag structure, enhancing Si diffusion into molten iron, significantly improving Si recovery, decreasing Ce retention in slag, and promoting inclusion migration. Experimentally, MgO increases the Si recovery rate from 47.67 to 73.78 pct, while CeO2 further increases it to 86.52 pct. The utilization rate of Ce increases from 63.12 to 89.2 pct. This integrated-melting route improves on the traditional two-step process, enabling efficient Fe–Si–Ce alloy production and providing a new approach for high-value, high-quality SWCW utilization.
Promoting dispersion of desulfurization flux within the hot metal bath in a Kanbara Reactor (KR) is of paramount significance to refining processes in steelmaking industries, as it dramatically enlarges the reactive interfacial area and thereby accelerates the rate phenomena governing slag-metal interactions, such as sulfur transfer from hot metal to slag. Exploring spatial distribution and dispersion mechanism of desulfurization flux driven by mechanical agitation are key points to essentially optimize operation parameters and reactor design of KRs, which are still challenging and not completely understood. The study focuses include visualizing the dispersion processes, evaluating dispersion degree and spatial distribution uniformity of desulfurization flux, and optimizing operating parameters and agitation regime. In this work, a 1/15-scale water model was established based on the modified Froude number similarity criterion to systematically investigate the dispersion of desulfurization flux in KRs under varying agitation conditions. Three typical dispersion characteristics were identified based on the relative contributions of impeller shear and vortex suction effects controlled by impeller immersion depth. In order to quantitatively evaluate the dispersion features, a novel post-treatment approach of observed image results through the water model experiments based on a developed Otsu’s threshold selection method was developed, which made it possible to effectively capture the particles regions in layer or of dispersed structures, and quantitatively evaluate effects of operation parameters. Three important indicators- dispersion rate, particle number density and particle uniformity index-were proposed for quantitatively evaluating dispersion degree, spatial distribution features and uniformity of desulfurization flux, respectively. The optimal impeller immersion depth was determined through quantitative analysis of the particle dispersion rate, and a novel agitation regime conducive to the dispersion of desulfurization flux with phased immersion depth setting was further proposed. The research offers systematic optimization strategies and reactor design recommendations for improving desulfurization performance in industrial KR operations.
