Papers by Keyword: Vanadium

Abstract: The catalyst with magnesium chloride supported vanadium/titanium bimetallic Ziegler-Natta catalysts has been prepared. The effects of V/Ti molar ratio and dosage of α-olefin on catalytic activity of ethylene polymerization were investigated. Gel permeation chromatography (GPC), ¹³C-NMR spectra and differential scanning calorimetry (DSC) analysis were performed to characterize the polymers. The results indicated that the bimetallic catalyst system produced PE with broad and bimodal MWD.

Abstract: Vanadium metal powder was successfully synthesized by combination reduction process with hydrogen gas and liquid magnesium. V₂O₅ as a raw material was first reduced by hydrogen gas to produce V₂O₃ at 873K for 3 hours and then it was reduced by liquid magnesium at 1,073K for 48 hours to become final vanadium powder. The microstructure and chemical composition of pure vanadium powder fabricated were examined by SEM(Scanning Electron Microscopy) and EDX(energy dispersive spectroscopy), respectively. The oxygen content of vanadium powder was finally found to be 0.5 wt.% showing the structure loosely agglomerated with fine particles of about 1~2μm.

Abstract: As one of the important strategic metals, Vanadium is applied widely to various fields, 85% of them are used in steel production. In this paper, the properties and the resource distribution of Vanadium are made a rough introduction, and introduced the present application situation of Vanadium in steel ,on-ferrous metals, alloys, batteries, chemical industry, ect.

Abstract: In this work, the physical and optical properties of soda-lime-borate glasses doped with V₂O₅ concentration of 0.0 to 2.5 in mol% have been investigated. The glass samples were prepared by the normal melt-quench technique. The results show that the density and refractive index decreased with additional 0.5 mol% content of V₂O₅. Then both results increased with increasing V₂O₅ content from 1.0-2.5 mol%. The optical absorption spectra of glass samples were measured by UV-visible spectrophotometer in the wavelength range 300-1100 nm and color coordinate in CIEL*a*b* system. The absorption peaks locate around 605 and 960 nm for all V₂O₅ concentration that are associated to V⁴⁺ ions and produce the brown color.

Abstract: An oxide film was prepared on AZ91D magnesium alloy by anodizing in solution containing sodium metavanadate (NaVO₃). The corrosion resistance of the AZ91D magnesium alloy was investigated at fixed current density 10 mA/cm² for 5 min with different concentration of solution in the range of 0 1.0 g/l. The surface morphology, cross section morphology, phase structure, and surface roughness of oxide film were studied by optical microscope, scanning electron microscope (SEM) and energy dispersive spectrometry (EDS), atomic force microscope (AFM) and potentiodynamic polarization technique and corrosion test, respectively.

Abstract: Based on the analysis of the properties of spent catalyst, extract vanadium and molybdenum from spent catalyst by roasting alkaline leaching. Sodium carbonate was leaching agent. The effects of roasting temperature, roasting time, the concentration of sodium carbonate and the number of leaching times on the leaching rate of vanadium and molybdenum were studied. Roasting temperature of 650°C, roasting time of 3h, the concentration of sodium carbonate of 50g/L and once counter-current leaching, under this condition, the leaching of vanadium is 83% and the leaching of molybdenum is 93%.Roasting alkaline leaching has good effect on extracting vanadium and molybdenum from spent catalyst.

Abstract: The effect of V contents (0, 0.03, 0.08 and 0.14%) on microstructure and mechanical properties was investigated in a Fe-Cr-Ni-Mo high-strength steel. Optical microscope (OM), electron back scattered diffraction (EBSD), transmission electron microscopy (TEM) and electron probe micro-analyzer (EPMA) were used to observe the microstructure varying in this paper. The results show that the prior austenite grain was refined obviously as increasing V content. Simultaneously, the amount of acicular ferrite (AF) increased and the size of that decreased. In addition, the size of carbide gradually decreased with increasing V content, and there appeared M₂C, M₆C and MC types of carbide after addition of V in the steel, while it is mainly M₂₃C₆ in the 0V steel (M is any combination of Cr, Mo, V or Mn). The strength and elongation increased gradually as increasing V content, meanwhile the impact toughness decreased gradually. The excellent combination of mechanical properties can be obtained in the steel with about 0.03% V content.

Abstract: Through the scanning electron microscope and energy spectrum analysis of vanadium slag after calcination at different temperatures of Panzhihua Iron and steel in industrial production, analyzed the change of morphology and composition of the various main phase, Focuses on the change process of two main vanadium containing phase which are vanadium spinels and calcium vanadate. The vanadium spinels into calcium vanadate optimal temperature range is 800 ~ 900 °C, and provides a theoretical basis for the extraction process of vanadium, which can further improve the industrial production of vanadium.

Abstract: In this paper, the extraction of vanadium from Chinese black shale by roasting with mixture salt addition was studied. The effect of salt additions, temperature and time on the recovery of vanadium were investigated by mixture salt roasting and 2% H₂SO₄ leaching. The mixture additions of Na₂CO₃-BaSO₄ was used in the roasting process. The optimal roasting conditions for black shale were determined to be 2.5 hours roasting at 760 °C with the mixture additive SB of 10-15%. After being leached with 2% sulphuric acid, the leaching efficiency of vanadium was obtained in 85%. The pollution of waste gas was decreased in the presence of BaSO₄-Fe₂O₃.

Abstract: The tri-n-octylmethyl-ammonium methyl carbonate was synthesized via a high pressure process with tri-n-octylamine(tri-C₈) and dimethyl carbonate(DMC) in the catalysis of tri-n-octylmethyl-ammonium bromine, and its chemical structure was confirmed using FTIR spectroscopic analysis. The influence of reactants molar ratio, reaction temperature, solvent, catalyst and reaction time on the quaternization reaction were examined, and the optimal conditions were that dimethyl carbonate(DMC):tri-n-octylamine(tri-C₈)=5.6:1(molar:molar), methanol:tri-n-octylamine (tri-C₈)=1:2 (volume:volume), catalysts 5% of the weight of reactant mixtures(materials fraction), reaction temperature 110°C and reaction time 8 h. Under the optimum conditions, the highest conversion rate of tri-n-octylamine(tri-C₈) could reach 99.57%. A type of SO₄^2- quaternary ammonium salt was prepared by the reaction between the product and H₂SO₄, and its properties on extracting vanadium in the feed solution from autoclave-soda leach solution of stone coal was researched, demonstrating that with 8% the type of SO₄^2- quaternary ammonium salt(QAS) and 5% sec-octyl alcohols dissolved in 87% sulphonated kerosene as extractant (volume fraction), the saturated loading capacity for V₂O₅ reaches 14.32 g/L.