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The non-Newtonian behavior and its mechanism have not been clarified for the solid-bearing silicate melts, leading to difficulties and even errors in estimating silicate melt viscosity. In this study, a typical metallurgical slag was employed as a model system of solid-bearing silicate melt. The flow behavior of the slag was measured via a rotational type rheometer at various shear rates. The results demonstrate that the slags exhibit non-Newtonian behavior for solid fractions exceeding a critical value (Φ c , i.e. 0.33–0.40 for the investigated samples), at which an abrupt viscosity increase occurs. Shear thinning (the viscosity decreases with increasing shear rate), thixotropy (a time-dependent shear thinning) and an apparent yield stress of 0.2–74.4 Pa for the investigated samples are the non-Newtonian characteristics observed in this study. The higher the solid fraction, the more pronounced the shear thinning. The shear thinning is mainly attributed to the disruption of crystal clusters. Thixotropic behavior is found to be caused by the irreversible microstructural evolution within the experimental time scale. The apparent yield stress is mainly due to the formation of a solid network and is increased with increasing the solid fraction. [ABSTRACT FROM AUTHOR]

To investigate the densification of porous alumina plugs, hydrogen measurements, using the Hydris probe system, were performed in molten steel with different oxygen levels at around 1600 °C. The oxygen contents in molten steel were controlled by Al and Fe-Si alloy additions to 664, 296, 92, 51 and 2.5 ppm, respectively. High oxygen levels (> = 92 ppm) in molten steel were found to favor the infiltration of steel into porous alumina plug. The infiltrating steel interacts with SiO 2 -containing phases and Al 2 O 3 inside the plug, forming liquid FeO n -Al 2 O 3 -SiO 2 slag and FeAl 2 O 4 (hercynite). These newly formed phases, along with the infiltrating steel fill the porous structure of the alumina plugs. As a result, severe densification was observed inside the alumina plugs in contact with molten steel containing high oxygen levels. In comparison, no densification occurred in the plugs contacting with the steel having low oxygen contents of 51 and 2.5 ppm. [ABSTRACT FROM AUTHOR]

Recycling of Nd-Fe-B magnets is one of the few solutions to alleviate the supply risks of certain rare earth elements (REE) such as Nd and Dy. One of the most promising solutions with regards to extraction of end-of-life (EOL) magnets is to apply hydrogen decrepitation and to physically separate the Nd-Fe-B as a demagnetized hydrogenated powder. Such a powder can be directly recycled into new sintered magnets, or indirectly recycled by a conventional oxidation roasting and acid leaching flowsheet. The oxidation stability of powders, the microstructure after oxidation and the role of compositional variations can be of importance for the success of such subsequent direct or indirect recycling routes. In this study, magnets with varying compositions were subjected to different hydrogen treatments (e.g. hydrogenation, partial or full degassing and vacuum or conventional disproportionation) and subsequently studied for their comparative oxidation behavior and microstructural changes. While initial magnet composition was found to have little or no effect on oxidation behavior, the treatment type was found to have a direct impact on both the particle size distribution and the oxidation mechanism. The general oxidation rate was found to be the equally highest for hydrogenated and partially degassed samples followed by fully degassed and then disproportionated samples. After complete oxidation, complex REE-Fe-O compounds were formed more extensively in hydrogenated and fully degassed NdFeB samples than in the disproportionated samples. [ABSTRACT FROM AUTHOR]

Multi-phase field simulation of Al SB 3 sb Ni SB 2 sb intermetallic growth at liquid Al/solid Ni interface using MD computed interfacial energies. Author Correction: Modeling of surface phenomena of liquid Al-Ni alloys using molecular dynamics Kunwar, A. I et al. i Multi-phase field simulation of Al SB 3 sb Ni SB 2 sb intermetallic growth at liquid Al/solid Ni interface using MD computed interfacial energies. [Extracted from the article]

We study the evaporation of antimony trioxide from an antimony-rich slag by bubbling nitrogen gas through a submerged top lance at 1000–1300 °C. Experiments are carried out with 300 g slag at gas flow rates of 20–60 l/h with the lance height of 1.5 and 10 mm. Slag samples are taken and analyzed to identify changes in the antimony trioxide content during the evaporation. By fitting the antimony trioxide content evolution of the slag to the calculation according to the integrated rate law, the antimony trioxide evaporation under the present conditions is found to be a second-order reaction. The evaporation rate constants and Sb recovery are enhanced with increasing temperature and gas flow rate and decreasing lance height. The deposited antimony trioxide product is characterized to determine its impurity level and microstructure. The rate-limiting step of the antimony trioxide evaporation is discussed, and the residual slag is analyzed to understand the antimony trioxide evaporation limits. • Sb 2 O 3 evaporation from an antimony-rich slag by bubbling nitrogen gas through a submerged top lance is studied. • Kinetics of the evaporation process was discussed by obtaining Sb 2 O 3 content-time curves and fitting them with rate laws. • The operating conditions for high Sb recovery and high Sb 2 O 3 purity were optimized. • The residual slag after evaporation was comprehensively characterized to understand the limits of evaporation. [ABSTRACT FROM AUTHOR]

Considering its application in developing Raney-type Ni catalysts and in metal surface coatings, the study on the growth behavior of Al 3 Ni 2 intermetallic compound (IMC) at the Al/Ni material interface is of utmost importance. The present work integrates nanoscale molecular dynamics (MD) calculation with mesoscale phase field model for studying the interfacial phenomena associated with Al 3 Ni 2 growth in Al/Ni interface at 1173.15 K. The interfacial energies computed from MD are in the range 0.9–1.2 J/m 2 with FCC/IMC featuring as the interface with the largest value and IMC/LIQUID as the one with the lowest value. Phase field model parameters characterizing a varying interface energy formulation are established to simulate the 2D growth of interfacial IMC grains. With the help of an atomistically informed phase field model, it has been revealed that the phase areas and morphology are obviously sensitive to the interfacial properties. The methodologies and results of these multiscale simulations for IMC interfaced between Al and Ni microstructures offer the complementary and accelerated design route of in-silico studies for materials systems experimented at high temperature. [Display omitted] • Interfacial energies computed using molecular dynamics. • Atomistically informed phase field simulation of growing IMC grains. • Comparison made between varying interface energy (VIE) and constant interface energy (CIE) models. • IMC area and morphology affected by interfacial properties. [ABSTRACT FROM AUTHOR]

• Arsenic is selectively removed from crude Sb 2 O 3 by leaching with HNO 3. • Conversion of Sb 2 O 3 to Sb(III)OHN releases As 2 O 3 from (As, Sb) 2 O 3 and contributes to the As removal. • The leaching residue can decompose to Sb 4 O 6 (g) and condense to Sb 2 O 3 (s). • A novel process for As removal and Sb recovery is proposed. The presence of arsenic (As) in crude antimony trioxide (Sb 2 O 3) impedes the Sb recovery and results in an environmental issue. Selective As removal from crude antimony trioxide would therefore enable using this residue in commercial Sb 2 O 3 production. This work uses a nitric acid leaching method to remove As from crude antimony trioxide. Arsenic oxide and antimony oxide are respectively converted to soluble H 3 AsO 4 and insoluble antimony(III) oxide hydroxide nitrate Sb(III)OHN during HNO 3 leaching. The As content in the crude antimony trioxide decreases from 3.0 wt% to 0.4 wt%. The As removal ratio reaches 86%, while the Sb leaching ratio is limited to 0.3%, confirming the high selectivity of HNO 3 leaching. The leaching residue is composed of cervantite (Sb 2 O 4) and Sb(III)OHN. By calcining the leaching residue in the air at 200 °C, it can be converted to a mixture of cervantite and valentinite (Sb 2 O 3). Finally, cervantite is decomposed above 1070 °C in N 2 into Sb 4 O 6 that can be condensed as Sb 2 O 3. A novel flowsheet is proposed for both As removal and Sb recovery from the crude antimony trioxide. [ABSTRACT FROM AUTHOR]

[Display omitted] • The spreading of liquid Al on solid Ni was studied by a combined sessile/pendant drop method between 750 °C and 950 °C. • Al 3 Ni was the first phase to form at the liquid/solid interface and it affected the final wetting properties. • Spreading dynamics conformed to the reaction-limited model. • The Al 3 Ni layer spread ahead of the liquid front at higher temperatures. Despite the importance in high-temperature processing, wettability studies focusing on liquid aluminum (Al) on solid nickel (Ni) at high temperatures are scarce due to the difficulty of performing experiments and the complexity of interfacial physical and chemical activities. The effects of interrelated multi-factors, including intermetallic compounds (IMCs) formation and diffusion on wetting dynamics is still debatable. Therefore, in this study, we investigated the reactive spreading of liquid Al on solid Ni by using the combined pendant/sessile drop method between 750 and 950 °C. The effects of Ni dissolution into Al on the spreading dynamics were limited due to the low Ni solubility below 950 °C. Two continuous Al-rich IMC layers, Al 3 Ni and Al 3 Ni 2 layers formed at the Al/Ni interface during the isothermal holding stage and affect the final wetting behavior. Additional capillary quenching experiments confirmed that the Al 3 Ni phase was the first formed phase. At equilibrium, the Al 3 Ni layer was pinned at the triple-phase line at 750 °C while it can spread ahead of the liquid front at higher temperatures. This process may be the main reason why at higher temperatures a better spreading is observed as the Al 3 Ni layer has a larger affinity to Al than the pure Ni substrate. [ABSTRACT FROM AUTHOR]

Despite the fact that aluminum is one of the most commonly-used elements, experimental results on the value of its surface tension are largely scattered due to the high sensitivity of aluminum to the atmospheric conditions, leading to huge experimental challenges. In this study, the surface tension of pure Al and Al-O systems was studied thoroughly using Molecular Dynamics (MD) simulations. A force field that includes embedded atoms method and charge transfer ionic potential was applied to account for interatomic interactions. To complement and validate the numerical approach, the surface tension of pure aluminum at two different temperatures was also measured. A good agreement was obtained between the measured and predicted surface tension. Simulations were then performed at different temperatures (1000–2200 K) with different initial oxygen contents to elucidate the effects of well-controlled atmospheric conditions on surface tension. Our results also show that the surface tension of aluminum is sensitive to the amount of oxygen content at the surface, which depends on the total oxygen content and the temperature. At various temperatures, different amounts of oxygen atoms are needed to saturate the aluminum surface (X O Sat.). A relationship between X O Sat. and temperature was derived. We believe that this study can shed light on the underlying mechanisms controlling surface tension of aluminum and could offer routes to better engineer the surface properties of this liquid metal. [Display omitted] [ABSTRACT FROM AUTHOR]

• The VOF-LES-DSL model predicts the turbulent top-submerged lance flow well. • 3D simulation is indispensable for capturing flow fluctuations. • The flow characteristics are quantitatively described under industrial conditions. The hydrodynamics of a gas-viscous liquid flow is numerically studied by coupling the Volume of Fluid (VOF) method with the Renormalization Group (RNG) k-ɛ model or Large Eddy Simulation (LES) (VOF-RNG or VOF-LES). The simulations are validated by Particle Imaging Velocimetry (PIV) measurements. Averaged flow features are predicted by 2D and 3D VOF-RNG/LES models. Only the 3D VOF-LES model predicts the velocity fluctuation well. The Dynamic Smagorinsky-Lilly (DSL) Subgrid-scale model slightly outperforms the Wall-Adapting Local Eddy-Viscosity (WALE) subgrid-scale model. Subsequently, flow characteristics of a gas-viscous liquid flow are studied by the validated 3D VOF-LES-DSL model under industrially relevant conditions. Gas penetration depth, flow velocity attenuation, surface sloshing and slag splashing are quantitatively described. The flow regime is identified through the pressure data monitored in the lance and its Fast Fourier Transform (FFT) results. The study of the coherent structures shows strong vortices in the top part of the slag pot. [ABSTRACT FROM AUTHOR]

The title compound is prepared by solid state reaction of Nd2O3, CaO, and SiO2 (sealed Pt-20%Rh tube, 1873 K, 1 d). [ABSTRACT FROM AUTHOR]

The application of plasma fuming technology opens up new horizons for the treatment of zinc-bearing residues. The present work uses a lab-scale Inductively Coupled Plasma (ICP) setup to investigate the hydrogen plasma reduction of ZnO and PbO from the CaO-FeO-SiO 2 based slags. Slag particles were melted when passing through the ICP torch, and the ZnO and PbO were reduced into Zn and Pb metal vapor by H 2 molecules and H radicals in the thermal hydrogen plasma. The metal vapor condensed on the particle surface when the particles passed through the plasma torch tail due to the high cooling rate. The PbO and ZnO content increased toward the particle core, implying the PbO and ZnO reduction from the slag particle surface. The increase in H 2 to Ar ratio or H 2 flow rate, power input and S content of the slags accelerated the process., Competing Interests: Conflict of interest The authors declare no conflicts of interest related to this work., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The dissolution of rare earth oxides in molten fluorides is a critical step in the preparation of the corresponding rare earth metals by oxide-fluoride electrolysis. However, quantitatively understanding the nature of dissolution, especially in the case of molten salts, is usually difficult to be achieved by postmortem characterization. In this paper, the dissolution behavior of Nd 2 O 3 particles in molten fluorides was studied via in situ observation with confocal scanning laser microscopy. Combining direct observation with thermodynamic analyses on the oxide dissolution, the rate-limiting step(s) and the effects of parameters like temperature, salt type, and composition on the dissolution rate are identified. This study provides a methodology to estimate the dissolution kinetics of rare earth oxides in molten fluorides during their primary and secondary processing., Competing Interests: The authors declare no competing financial interest.