Xingrong Wu

Growth of phosphorus concentrating phase in modified steelmaking slags

Abstract Recycling steel slag to metallurgical process requires removing phosphorus from slag. In this paper, solidification experiments of converter slag modified by SiO2 at three isothermal temperatures with several durations were performed at air conditions from superheating temperature (1520°C). Grain size evolution of P concentrating phase (C2S, dicalcium silicate) was investigated. Results show that crystal size distributions of C2S can be fitted by lognormal distributions, the average size of C2S increases with increasing dwelling time and grows faster at higher holding temperature, and the relationship between average size of C2S and holding time can be best described by equation D = ktm. It is concluded that the growth mechanism of C2S is diffusion controlled, and higher isothermal temperature promotes the growth of C2S. Le recyclage de la scorie de l’acier par un procédé métallurgique nécessite l’enlèvement du phosphore de la scorie. Dans cet article, on discute d’expériences de solidification de scorie de convertisseur modifiée par du SiO4 à trois températures isothermes avec durées variées, effectuées à l’air à partir d’une température de surchauffage (1520°C). On a examiné l’évolution de la taille de grain de la phase de concentration du P (C2S, silicate dicalcique). Les résultats montrent que l’on peut ajuster les distributions de la taille de cristal (CSD) du C2S à une distribution log-normale, que la taille moyenne du C2S augmente avec l’augmentation du temps de résidence et croît plus vite à une température plus élevée de rétention et que la relation entre la taille moyenne du C2S et la durée de rétention est bien décrite par l’équation D = ktm. On conclut que le mécanisme de croissance du C2S est contrôlé par la diffusion et que la température isotherme la plus élevée favorise la croissance du C2S.

A Novel Conversion of Ti-Bearing Blast-Furnace Slag into Water Splitting Photocatalyst with Visible-Light-Response

A novel visible-light-response photocatalyst was prepared through the heat treatment of Ti-bearing blast-furnace slag with sodium nitrate and subsequently leaching processes in which most of the SiO2, Al2O3, and MgO in Ti-slag (TS) have been separated. The photocatalytic activity of the TTS was studied by observing the evolution of H2 under the UV–Vis and visible light. Compared with the TS and commercial perovskite CaTiO3, the sample prepared exhibited an exclusive visible-light-response activity and enhanced H2 evolution.

Preparation of Eu3+-Y3+ Coactivating Na+ Based Red-Emitting Luminous Materials for Light-Emitting Diodes and Investigation of Its Characteristics

By solid-state reaction and doping, a series of red-emitting phosphors NaxY0.92–x/3(MoO4)y(WO4)1–yO0.5 : zEu3+ have been synthesized. Through optimization of the process conditions and photoluminescent analysis, one type of red emission is obtained that matches nicely with ultraviolet light-emitting diode (UV-LED) chips.

Infrared Emissivity of La0.8Sr0.2MnO3 with Three Different Structures

La0.8Sr0.2MnO3 samples with rhombohedral, orthohombic and monoclinic structures were prepared by solid state reaction, sol-gel and co-precipitation methods, respectively. Lattice parameters, grain size, morphology, infrared absorption and emissivity of samples were investigated. The results indicated that the average crystallite size calculated from XRD result and particle size of orthohombic sample were smaller than those of the other two samples, and honeycomb shape grains were observed in orthohombic sample. Due to lower crystal symmetry, Mn-O stretching vibration peaks of the three samples shifted to higher infrared wavenumber. According to the theory of wave optics and Kirchhoff law, bigger rhombohedral sample showed higher emissivity than monoclinic one. However, due to the honeycomb structure of orthohombic sample, repeated reflection and scattering led to the increase of absorption, and orthohombic sample exhibited the highest emissivity.

Polymerization behavior of silicic acid with Fe3+, Al3+, and Ca2+ coexisting ions

Silicic acid was prepared by acid hydrolysis of water-quenched calcium silicate, and Ca2+, Al3+, and Fe3+ were added to investigate the polymerization behavior. Effect order of the three ions on the polymerization was Fe3+ > Al3+ > Ca2+. Due to decreased polymerization rate caused by Fe3+ at pH < 3, average diameter of the colloidal particles at pH = 2 was larger than that at pH = 3. New infrared absorption peaks were found at 2360 cm−1 which may be attributed to Ca–OH, Al–O–Si, and Fe–O–Si, respectively, and it was especially obvious for Fe3+. For three ions coexisting system, the new peak showed a slight shift to 2370 cm−1. Preventing ability of Fe3+ on water binding is much stronger than promoting ability of Al3+. Dehydration process of bound water was hindered by adding the three ions, and due to higher bound water content, endothermic peak for Al3+ system was stronger. Crystallization process was hindered by Ca2+ and Fe3+.Graphical abstract

Co-precipitation behaviour of titanium-containing silicate solution

The co-precipitation behaviour of a simulated Al2(SO4)3-TiOSO4-Na2SiO3 solution that imitated the lixivium of Ti-bearing blast furnace slag (Ti-slag) leached by sulphuric acid was investigated in this study. Various chemical analyses were employed to study the selective precipitation of multiple target components. Based on the high-added-value applications of Ti-slag, a new method was developed to prepare aluminium titanate composites from titanium-containing silicates. The findings demonstrate that the onsets of Ti and Al precipitation occur at pH values of 3.5 and 5.0, respectively, followed by Si precipitation. The particle sizes of the co-precipitates were greatly influenced by the precipitants, pH and the initial Al/Ti mole ratio. The results also show that the precipitation ratio of Ti, Al and Si generally increases with the pH and temperature, regardless of the Al/Ti mole ratio. The Si-O-Al, Ti-O-Al, and Ti-O-Si bonds that were formed were dependent on the pH and the initial Al/Ti mole ratio. There was a synthesis path for β-Al2TiO5 (AT) from the solid-state reaction between rutile and α-Al2O3 at 1362.5°C. The AT composites were successfully prepared by sintering the co-precipitates at 1450°C, which exhibited good thermal stability as estimated by the XRD measurements of the sample annealed at 1200°C for 4 hours.