Abstract The vanadium and chromium have an extremely high potential for application in ceramics. High‐chromium vanadium slag, a by‐product of the smelting of high‐chromium vanadium‐titanium magnetite, contains significant vanadium and chromium resources. However, the lack of thermodynamic studies on oxide systems containing VO x and CrO x has limited their efficient utilization. In this study, the phase equilibrium experiments of the “FeO”‐SiO 2 ‐CaO‐V 2 O 3 ‐VO 2 ‐Cr 2 O 3 system were carried out at 1400°C under P O2 = 10 −10 atm, and the corresponding isothermal section diagram was constructed. The results showed that vanadium and chromium were mainly crystallized as Fe(V,Cr) 2 O 4 and (Fe,V,Cr) 2 O 3 , and Fe(V,Cr) 2 O 4 had higher crystallization ability. Furthermore, the influence of basicity, “FeO” content, and temperature on the thermodynamic behavior of vanadium and chromium was further investigated in the coexistence region of Fe(V,Cr) 2 O 4 +Liquid. It was found that the crystallization of vanadium and chromium was inhibited with the decreasing “FeO” content; the increase in basicity inhibited the crystallization of vanadium but facilitated the crystallization of chromium; the decrease in temperature significantly enhanced the crystallization of vanadium but had a weaker effect on the crystallization of chromium. This study provides the basic thermodynamic data for the efficient utilization of high‐chromium vanadium slag.
A novel approach for quickly separating a metal copper phase and iron-rich phase from copper slag at low temperature is proposed based on a super-gravity m
The investigations of concentrating iron, slag and britholite-(Ce,La,Pr,Nd) from gaseous reduced Bayan Obo ore were conducted at 1473 K in a super gravitational field. The results showed that iron grains concentrated at the bottom area along super gravitational direction, whereas the gangue formed the slag in the upper area along the opposite direction, as well as the REEs enriched into britholite-(Ce,La,Pr,Nd) with a typical hexagonal structure and concentrated in the bottom slag. Moreover, the effects of gravity coefficient on both iron-slag separation and the concentration of REEs precipitates were investigated further.
Five new diarylheptanoids (1–5), along with nine known ones (6–14), were isolated from the rhizomes of Curcuma kwangsiensis. Their structures were established on the basis of spectroscopic analyses. Compounds 1–3 were cyclic diarylheptanoids rarely discovered from C. kwangsiensis. Of all the isolated compounds, compound 4 showed moderate antiproliferative activity on HH and HaCaT cells.
An entry from the Inorganic Crystal Structure Database, the world’s repository for inorganic crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the joint CCDC and FIZ Karlsruhe Access Structures service and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Mass transfer is a critical scrap melting step. Herein, mass transfer coefficients (k) during scrap melting were calculated using laboratory-scale experiments. Correlation analysis and the entropy weight method were used to determine the effect of variables on k. The evaluation model under natural and forced convection was established. It was consistent with the experimental results. Under forced convection, at 1573 and 1673 K, when the rotation speed was increased from 141 to 423 r/min, k increased from 7.50 × 10−5 to 1.54 × 10−4 m/s and from 8.42 × 10−5 to 1.72 × 10−4 m/s, respectively. Furthermore, as the bath temperature was increased from 1573 to 1723 K, the k value of a stationary specimen increased from 3.14 × 10−5 to 5.31 × 10−5 m/s, respectively. Correlation analysis and the entropy weight method indicated that the effects of variables on k decreased as follows: molten pool stirring rate > bath temperature > scrap type. Moreover, the explicit functional relationships between k and the factors affecting k under natural and forced convection conditions were established, and the results were consistent with the experimental data. Our results can be used to determine the quantitative relationships between k and the factors affecting k.
An entry from the Inorganic Crystal Structure Database, the world’s repository for inorganic crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the joint CCDC and FIZ Karlsruhe Access Structures service and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Re-concentrate is a complex multi-components Re-system consisting of Ce, La, Pr and Nd, which brings great difficulties for investigating the transformation and separation behaviors of REEs. The effect of super-gravity field on the mass transfer and phase separation behaviors of REEs was investigated in this paper, and the phenomenon of successive precipitation and separation of REEs was discovered. The Re3+ was firstly precipitated into Re-oxyfluoride phase with OF3-, which overcame the interface tension to be evidently separated into the bottom layer under the action of super gravity. Subsequently, the Re3+ were successively precipitated with FeO3 3-, SiO4 4- and PO4 3- into Re-ferrate phase and britholite phase, which were separated further into the middle and top layers along the super gravity direction. Moreover, various REEs were efficiently recovered into the different Re-phases, respectively. The theoretical and experimental results verified the significant enhancement of super gravity on the mass transfer and phase separation of REEs, and its efficient application in REEs recovery from multi-component Re-system.
It reports the selective crystallization and separation of Ti in Ti-bearing slag. The selective crystallization of Ti into perovskite, the phase transformation of Ti into rutile, the crystallization behavior of Ti into anosovite, and the carbothermal reduction of Ti into TiC in Ti-bearing slag are reported in Sects. 2.1, 2.2, 2.3, and 2.4, respectively. The study on selective separation of various Ti–rich phases of perovskite, rutile, anosovite, and TiC powders in molten Ti-bearing slag is included in the Sects. 2.1, 2.2, 2.3, and 2.4, respectively. The amplification study for selective separation of Ti in Ti-bearing slag is reported in Sect. 2.5.
The competitive crystallization, in situ separation, and solidification mechanism of Cr-spinel crystals were studied and the occupancy of Cr in the Cr-spinel lattice remained constant with the substitution of Fe and Mn.
Super gravity technology was used to separate the phosphorus- and iron-enriched phase from CaO-SiO2-FeO-MgO-P2O5 melt. The microstructure and X-ray diffrac
Ultrafine TiC powders possess excellent physicochemical properties, which are mainly synthesized by using high-purity ultrafine Ti or TiO2 powders. In this study, a sustainable method for recovery of ultrafine TiC powders from molten Ti-bearing slag under super-gravity field was proposed. Firstly, the solid-liquid coexistence condition for single TiC powders in molten Ti-bearing slag was acquired. On this basis, the motion mechanism and separation behavior of TiC powders in the molten slag was studied. Under the force of super-gravity, all of TiC powders were efficiently separated from the molten slag along the super-gravity direction, and the Ti recovery ratio reached 96.69%. Moreover, the recovered TiC powders were confirmed to be high purity (w (Ti) = 79.49%) and ultrafine particles (particle size 2.75 μm on average). Compared with synthetic methods, this study provides a sustainable way to produce ultrafine TiC powders for clean utilization of massive Ti-bearing slag.
As an environmentally hazardous waste, silica fume was considered as a potential alternative for cement and SiO2 production. The structure of Si–O was highly relevant to the reactivity of Si conversion for efficient utilization. In this study, the characteristic and chemical structure of Si–O in silica fume were characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR). Deconvolution of XPS and FTIR spectra into elementary profiles was carried out to analyze the structural components. As a result, the valence state, bonding structure and elementary unit in the Si–O network of silica fume were determined. Then, the reactivity silica fume with alkali solution was studied involving the effects of NaOH concentration and temperature. The staged kinetics behavior was associated with the structure of Si–O bonds, and the activation energies were determined. The results thus provided fundamental information for the utilization of silica fume for SiO2 production and geopolymer.
A new approach of removing the phosphorus-rich phase from high-phosphorous iron ore by melt separation at 1573 K in a super- gravity field was investigated
The effects of super-gravity field on metal–slag separation at different gravity coefficients were investigated in this study. In a super-gravity field, the liquid metal concentrated along the direction of super-gravity, while the molten slag migrated and aggregated along the opposite direction thereafter separated from the metal. Moreover, a straight interface between the metal and slag appeared in the perpendicular direction to the super-gravity. Consequently, increasing the gravity coefficient could definitely increase the driving force of phase separation between metal and slag, and so enhance the removal of oxide and the purity of metal significantly.
Reports the selective crystallization and separation of REEs in RE-concentrate. The mineral evolution and mineral reconstruction behaviors of RE-concentrate are reported, and the study on selective concentration and selective separation of cerium oxyfluoride in RE-concentrate is included in Sects. 5.1 and 5.2, respectively. The study on stepwise crystallization, stepwise concentration, and stepwise separation of REEs (Ce, La, Pr, Nd) in RE-concentrate is included in Sect. 5.3.
Sustainable utilization of rare earth elements (REEs) in REE-bearing slag has recently attracted significant interest in industries and research community. However, few thermodynamic and kinetic data have been reported for REEs systems, which greatly limits the sustainable utilization of REE-bearing slag in ceramics and other fields. Therefore, the isothermal phase diagram of CaO–SiO2–CaF2–Ce2O3 system was constructed, and the phase equlibria data of REEs in REE-bearing slag were provided in this study. On this basis, the phase equilibria of the RE-phase in CaO–SiO2–CaF2–Ce2O3 system was investigated, the exact initial crystallization temperature of cefluosil (Ce9.33-xCax(SiO4)4O5-0.5xF2) in the system was 1450 K and the cefluosil crystals were in a hollow hexagonal prism shape. The isothermal crystallization and growth kinetics of cefluosil were further studied. The crystallization kinetics of cefluosil were found to be described by the Johnson-Mehl-Avrami-Kolmogoro (JMAK) equation (when χ < 1), and the growth of cefluosil in the non-equilibrium stage is controlled by the coarsening energy. In this research, the thermodynamic and kinetic data of REEs in CaO–SiO2–CaF2–Ce2O3 system are supplied, which providing the theoretical basis for sustainable utilization of REEs in REE-bearing slag.
With the massive consumption of rare earth resources, the recovery of rare earth elements (REEs) from secondary resources has become a focus of attention. It is economically necessary to recover REEs from Bayan Obo RE-containing blast furnace slag (RE-BFS), which contains considerable REEs. However, due to the lack of relevant thermodynamic data, it is difficult to effectively recover REEs from RE-BFS. Therefore, the isothermal phase diagram of CaO–SiO2–Al2O3–Ce2O3 at 1100 °C was constructed in this work, according to the principle of phase diagram construction combined with the method of equilibrium experiments. The optimal rare earth equilibrium phase in this system was defined as Ce4.667-xCax(SiO4)3O1-0.5x. According to the actual composition of the RE-BFS, a dominant separation region of L + Ce4.667-xCax(SiO4)3O1-0.5x was obtained in the phase diagram. Subsequently, the extraction of REEs in the RE-BFS could be completed by solid–liquid separation, which allowed economic benefits without affecting the environment. The data reported in this work provide a theoretical basis for solving the problem of recovery from RE-containing secondary resources and developing high value-added materials.
