Effects of smelting parameters on the slag/metal separation behaviors of Hongge vanadium-bearing titanomagnetite metallized pellets obtained from the gas-based direct reduction process

Smelting separations of Hongge vanadium-bearing titanomagnetite metallized pellets（HVTMP）prepared by gas-based direct reduction were investigated,and the effects of smelting parameters on the slag/metal separation behaviors were analyzed.Relevant mechanisms were elucidated using X-ray diffraction analysis,FACTSAGE 7.0 calculations,and scanning electron microscopy observations.The results show that,when the smelting temperature,time,and C/O ratio are increased,the recoveries of V and Cr of HVTMP in pig iron are improved,the recovery of Fe initially increases and subsequently decreases,and the recovery of Ti O_2 in slag decreases.When the smelting Ca O/Si O_2 ratio is increased,the recoveries of Fe,V,and Cr in pig iron increase and the recovery of Ti O_2 in slag initially increases and subsequently decreases.The appropriate smelting separation parameters for HVTMP are as follows：smelting temperature of 1873 K;smelting time of 30–50 min;C/O ratio of 1.25;and Ca O/Si O_2 ratio of 0.50.With these optimized parameters（smelting time：30 min）,the recoveries of Fe,V,Cr,and Ti O_2 are 99.5%,91.24%,92.41%,and 94.86%,respectively.

Metallic vanadium trioxide intercalated with phase transformation for advanced aqueous zinc-ion batteries

Aqueous zinc-ion batteries have broad application prospects due to the eco-friendliness,cost-economy and high safety.However,the scarcity of high-performance cathodes with outstanding rate capability and long lifespan has affected their development.Herein,we report a metallic vanadium trioxide material intercalated with phase transformation as cathode applied in aqueous zinc-ion batteries.It offers satisfactory electrochemical performances with a high specific capacity(435 mAh g^(-1) at 0.5 A g^(-1)),decent power density(5.23 kW kg^(-1))and desired energy density(331 Wh kg^(-1)),as well as good cyclability.The superior performance originates from the stable structure and fast Zn^(2+)diffusion,enabled by the pre-intercalation of Zn^(2+)and water molecules.

Thermodynamic analysis on the direct preparation of metallic vanadium from NaVO_3 by molten salt electrolysis

A novel and environmentally friendly route to directly prepare metallic vanadium from Na VO_3 by molten salt electrolysis is proposed.The feasibility about the direct electro-reduction of NaVO_3 to metallic vanadium is analyzed based on the thermodynamic calculations and experimental veri fications.The theoretical decomposition voltage of NaVO_3 to metallic vanadium is only 0.47 Vat 800°C and much lower than that of the alkali and alkali earth metal chloride salts.The value is slightly higher than that of low-valence vanadium oxides such as V_2O_3,V_3O_5 and VO.However,the low-valence vanadium oxides can be further electro-reduced to metallic vanadium thermodynamically.The thermodynamic analysis is veri fied by the experimental results.The direct preparation of metallic vanadium from NaVO_3 by molten salt electrolysis is feasible.

Fabrication and Analysis of Vanadium-Based Metal Powders for Selective Laser Melting

Vanadium Alloy is a type of advanced nuclear material with many ideal properties compared as traditional nuclear materials, which has very wide and important application in first-wall and blanket structural material for fusion power plant applications. So it has attracted increasing attentions, especially on new manufacturing methods, such as selective laser melting and so on. In this paper, the comparative study of the powders obtained by mechanical mixing method, dry grinding method and wet grinding method respectively was performed to evaluate the effect of ball milling process on the microstructure and degree of alloying of the vanadium-based powder mixtures with the nominal composition of V5Cr5Ti vanadium alloy. The powders prepared by dry grinding method exhibits better spherical-like morphology and degree of alloying than those prepared by mechanical mixing method and wet grinding method, which indicates that dry grinding method can be used to prepare the superfine vanadium alloy powders for selective laser melting. This work provides a new method as well as important insights into the preparation of superfine vanadium alloy powders for selective laser melting additive manufacturing technology.

二氧化钒发射率的调控方法与实践

二氧化钒(VO_(2))是一种常用的相变材料,它能在68℃附近可逆地改变光学、电学特性以响应外部温度刺激。自20世纪90年代以来,人们对VO_(2)光学特性进行了广泛的研究,并在紫外、可见和近红外区域的调制方面取得了重大进展,而室温黑体辐射所处的中远红外区能量只相当于太阳辐射的15%,因而获得的关注较少。然而随着研究的深入,研究者发现中远红外光区的长波辐射对热调控也具有至关重要的作用,甚至在太阳辐射较强的白天也是不容忽视的,因此有关VO_(2)发射率调控的研究受到越来越多的关注。文章聚焦VO2发射率调控的最新研究进展,着重介绍VO_(2)发射率的调控手段以及常温热辐射调控性能,并对其应用前景进行了展望。文章指出,VO_(2)发射率可以有效调控室温黑体辐射能量,通过新型结构如Fabry-Pérot谐振腔、超材料等与VO_(2)的有机结合,极大丰富了VO_(2)发射率的调控手段,展现出显著的调控效果,这对于实现具有更高节能效率的智能建筑、空间热管理以及红外伪装具有很大的潜力。

VO_(2)薄膜材料的变温光学性质及1550 nm激光防护性能研究

具有半导体-金属态相变性质的二氧化钒材料可用于光电探测器的激光致盲防护。本文报道了基于磁控溅射法制备二氧化钒薄膜材料的结构、形貌特性,以及在不同温度下的光学性质。使用椭偏光谱法测量了20~100℃下可见-近红外波段二氧化钒材料的椭偏参数,利用Gaussian、Lorentz模型获取了薄膜在相变前的光学性质,结合Drude模型拟合获取了材料在相变后的光学特性,获取了材料在300~1700 nm之间的变温折射率和消光系数等参数。变功率下1550 nm红外激光透射率的实验测试研究表明,VO_(2)薄膜样品的相变阈值功率为12 W/cm^(2),相变前后透射率由51%减小到15%~17%,开关率为69%。

钒氧化物及金属钒酸盐在化学储能中的应用

钒氧化物具有多变的配位数和氧化态、较低的成本、丰富的资源等优点,作为典型的过渡金属氧化物,其应用于锂离子电池电极材料时具有良好的锂离子存储能力和较强的循环能力。钒氧化物在超级电容器中表现出高功率密度、快速充放电率和优良的循环周期等特性,是一种理想的储能材料,而金属钒酸盐显示出良好的可逆性和循环性。构筑合理纳米结构是获得电化学性能优异钒氧化物电极材料的有效途径,是提高电极材料放电/充电效率的最有效方法之一。综述了钒氧化物和金属钒酸盐在锂离子电池中应用以及钒氧化物在超级电容器中应用的研究进展,讨论了结构、制备条件对钒氧化物及金属钒酸盐性能的影响,展望了钒氧化物及金属钒酸盐的应用前景。

四硫化钒复合石墨烯材料的制备及其锂离子电池性能研究

四硫化钒(VS_(4))作为具有高硫含量三明治结构的一维(1D)链状钒硫化合物,S_(2)二聚体与两个相邻的V原子配位,每个单链通过弱范德华力相互作用,松散堆叠的链有利于Li^(+)的快速扩散,因而被认为是有前途的锂离子电池负极候选者。通过水热法设计并合成了四硫化钒复合还原氧化石墨烯(VS_(4)@rGO)负极材料,VS_(4)纳米棒紧密地固定在氧化石墨烯薄片上,氧化石墨烯的加入一方面保证了良好的导电性,另一方面也抑制了VS_(4)纳米棒团聚成球以释放更多活性位点,从而有效提高锂离子电池的性能。作为锂离子电池负极,VS_(4)@rGO电池的充放电性能出色,进行倍率测试时,在0.2,0.5,1.0,2.0和5.0 A·g^(-1)的电流密度下,平均放电比容量分别为983,797,666,547和397 mAh·g^(-1)。在5 A·g^(-1)的高电流密度下可保持循环3000次,比容量稳定在141.6 mAh·g^(-1),平均每圈的容量衰减率仅为0.019%。这项工作为其他过渡金属硫化物的结构设计提供了新的思路。

钒基储氢合金的特点和应用前景

钒基储氢合金具有储氢密度高、储放氢反应条件温和、储氢动力学性能优越、抗粉化性能好等优点,是一种优良的储氢材料。但是钒基储氢合金存在放氢平台压低、可逆储氢量低、储放氢滞后现象明显、循环稳定性差、原料价格高、金属成本高等缺点,制约着钒基储氢合金进一步推广应用。迄今为止,研究者们从元素组成和晶相结构等多种途径对其进行改性,以优化钒基储氢材料性能。基于此,以降低氢化物的放氢平台压和提高材料可逆储氢量为出发点,简述了掺杂Ti,Cr,Mn,Zr等化学元素和对于储氢合金进行特定条件优化改善的研究进展,着重阐述了元素置换、材料热处理和合金活化预处理对钒基储氢合金储氢性能的影响,展望了钒基储氢合金未来发展前景。

储能电池建模与状态估计研究进展

储能电池具有能够平滑可再生能源输出,提高电力系统灵活性和应对电力需求峰谷等优势,有助于推动可再生能源发展,从而应对环境污染和能源紧缺的双重压力。目前市场主流的储能电池为锂离子电池,具有高比能特性,同时新型储能电池也在蓬勃发展,其中全钒液流电池具有高安全性的优势,液态金属电池具有超长循环寿命,在电力储能领域具有重要应用前景。储能电池的建模和状态估计对提高储能电池系统性能,确保其安全性以及优化维护效率至关重要,因此文中对锂离子电池、全钒液流电池和液态金属电池的建模和状态估计进行综述。首先,介绍了储能电池状态估计的整体框架,对基于实验的方法、基于模型的方法和基于数据驱动的方法进行整体介绍,并对荷电状态(state of charge,SOC)、健康状态(state of health,SOH)和剩余使用寿命(remaining useful life,RUL)进行概括;然后,从原理出发,分别总结了不同储能电池体系的内部工作过程、模型构建、状态估计与电池管理过程;最后,对不同储能电池体系的主要工作特性进行横向对比和总结,旨在为储能电池选择和发展提供启示。

Chemical Treatment to Recover Molybdenum and Vanadium from Spent Heavy Gasoil Hydrodesulfurization Catalyst

Large quantities of spent hydrodesulfurization (HDS) catalysts are available from petrochemical industry. Disposal of spent catalyst is a problem as it falls under the category of hazardous industrial waste due to its vanadium concentration. Most of these catalysts are usually supported on alumina containing a variable percentage of elements such as nickel or molybdenum. Hence these catalysts contain environmentally critical, and economically valuable metals such as molyb denum, vanadium, and, nickel. In this paper, a spent HDS catalyst was treated with caustic soda solution. Parameters such as temperature, time, and NaOH solution concentration have been studied thoroughly, in order to settle the appropriate conditions for the maximum recovery of molybdenum and vanadium. Under the best leaching conditions (20 %w NaOH, room temperature, 2 h) about 95% recovery of Mo and V was achieved, and the recovery of nickel obtained was of 99% in the form of NiAlO4.

Review of Vanadium Processing in China

There are abundant resources of vanadium in China distributed over 10 provinces. Vanadium is an important by product that can is used almost exclusively in ferrous and non-ferrous alloys due to its physical properties such as high tensile strength, hardness, and fatique resistance. Vanadium consumption in the iron and steel industry represents about 85% of the vanadium -bearing products produced worldwide. The ubiquitous vanadium is used in a wide range of alloys in combination with iron, titanium, aluminum, chromium, and other metals for a diverse range of commercial applications extending from train rails, tool steels, catalysts, to aerospace. This paper introduces information about vanadium in China, its main producers and main applications.

Molecular Simulation Study on Interaction of Thiophene Sulfides with Transition Metals

The computer molecular simulation technique was applied to study the chemisorption of thiophene and tetramethylthiophene as the model sulfides on the simple oxides and complex oxides of some transition metals as the catalytic materials. The study disclosed that the thiophene sulfides could enter into chemisorption with metal oxides such as VO, ZnO, NiO and Zn-Al-spinel. This interaction could lead to thiophene molecular structure deformation to be in an activated adsorption state, which could help to promote the conversion of thiophene sulfides in the course of catalytic cracking. The VO with a valence of 2 could provide relatively strong selective adsorption sites for the conversion of thiophene sulfides to apparently transform the molecular structures and electron cloud states of such heterocyclic sulfur compounds such as thiophene and tetramethylthiophene into an activated adsorption state. The effect of this interaction was more pronounced with respect to tetramethylthiophene.

Effects of calcium compounds on the carbothermic reduction of vanadium titanomagnetite concentrate

Effects of calcium compounds on the carbothermic reduction of vanadium titanomagnetite concentrate(VTC) were investigated. It was found that calcium compounds had great effects on the metallization rate of the reduction product, the order of the metallization rate of reduction product being CaCO3 > no additive > CaSO4 > CaCl2, which indicated that the addition of CaCO3 was more conducive to promoting the reduction of iron than other calcium compounds. Gas analysis showed that there were mainly two processes in the carbothermic reduction of VTC, a solid–solid and a solid–gas reaction. The concentrations of CO and CO2 were highest when CaCO3 was added, while that in a roasting system decreased the most when CaCl2 was added. X-ray diffraction(XRD) analysis showed that calcium compounds could change the reduction process of ilmenite in VTC. The phase compositions of the reduction products were changed from metallic iron(Fe) and anosovite(FeTi2O5) to metallic iron(Fe) and perovekite(CaTiO3) when calcium compounds were added. Additionally, CaSO4 and CaCl2 could significantly promote the growth of metallic iron particles, though the existence of Fe-bearing Mg2TiO4 in reduction products was not conducive to the reduction of iron. The formation of FeS would further hinder the reduction of iron after adding CaSO4.

Effects of Vanadium Oxidation Number on Light Olefins Selectivity of FCC Catalyst

Effects of vanadium on light olefins selectivity of FCC catalysts were investigated with vanadium having different oxidation numbers(hereinafter abbreviated as Oxnum).Molecular modeling studies showed that vanadium with low Oxnum could affect the chemical conversion of large-size hydrocarbon molecules.However,the vanadium deposited on equilibrium catalyst had high Oxnum because of the oxidation reaction taking place in the regenerator,so an activation method to reduce vanadium Oxnum named "selective activation" was introduced.It was proved by means of Electron Paramagnetic Resonance(EPR) and Temperature-Programmed Reduction(TPR) methods that the vanadium Oxnum was decreased,when the catalyst was activated.The molecular modeling studies are consistent well with the lab evaluation results.The light olefins selectivity of activated equilibrium catalysts was better than that achieved by the inactivated catalysts.Similar results were observed with the lab vanadium-contaminated catalyst.The light olefins selectivity of the catalyst was optimized when the vanadium Oxnum was close to 2(VO).

Fabrication of VO_2 thin film by rapid thermal annealing in oxygen atmosphere and its metal–insulator phase transition properties

Vanadium dioxide thin films have been fabricated through sputtering vanadium thin films and rapid thermal annealing in oxygen. The microstructure and the metal-insulator transition properties of the vanadium dioxide thin films were inves- tigated by X-ray diffraction, X-ray photoelectron spectroscopy, and a spectrometer. It is found that the preferred orientation of the vanadium dioxide changes from （111） to （011 ） with increasing thickness of the vanadium thin film after rapid thermal annealing. The vanadium dioxide thin films exhibit an obvious metal-insulator transition with increasing temperature, and the phase transition temperature decreases as the film thickness increases. The transition shows hysteretic behaviors, and the hysteresis width decreases as the film thickness increases due to the higher concentration carriers resulted from the uncompleted lattice. The fabrication of vanadium dioxide thin films with higher concentration carriers will facilitate the nature study of the metal-insulator transition.

In situ electronic structural study of VO_2 thin film across the metal–insulator transition

The in situ valence band photoemission spectrum （PES） and X-ray absorption spectrum （XAS） at V LⅡ-LⅢ edges of the VO2 thin film, which is prepared by pulsed laser deposition, are measured across the metal–insulator transition （MIT） temperature （TMIT=67 ℃）. The spectra show evidence for changes in the electronic structure depending on temperature. Across the TMIT, pure V 3d characteristic d‖ and O 2p-V 3d hybridization characteristic πpd, σpd bands vary in binding energy position and density of state distributions. The XAS reveals a temperature-dependent reversible energy shift at the V LⅢ-edge. The PES and XAS results imply a synergetic energy position shift of occupied valence bands and unoccupied conduction band states across the phase transition. A joint inspection of the PES and XAS results shows that the MIT is not a one-step process, instead it is a process in which a semiconductor phase appears as an intermediate state. The final metallic phase from insulating state is reached through insulator–semiconductor, semiconductor–metal processes, and vice versa. The conventional MIT at around the TMIT=67 ℃ is actually a semiconductor–insulator transformation point.

A novel process for the recovery of iron,titanium,and vanadium from vanadium-bearing titanomagnetite:sodium modification–direct reduction coupled process

A sodium modification–direct reduction coupled process was proposed for the simultaneous extraction of V and Fe from vanadium- bearing titanomagnetite. The sodium oxidation of vanadium oxides to water-soluble sodium vanadate and the transformation of iron oxides to metallic iron were accomplished in a single-step high-temperature process. The increase in roasting temperature favors the reduction of iron oxides but disfavors the oxidation of vanadium oxides. The recoveries of vanadium, iron, and titanium reached 84.52%, 89.37%, and 95.59%, respectively. Moreover, the acid decomposition efficiency of titanium slag reached 96.45%. Compared with traditional processes, the novel process provides several advantages, including a shorter flow, a lower energy consumption, and a higher utilization efficiency of vanadium-bearing titanomagnetite resources. © 2017, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

金属有机骨架衍生的钒碳催化剂催化氧化乳酸乙酯制备丙酮酸乙酯

化石能源的过度开发利用造成的能源危机和环境问题促使研究人员尝试利用可再生能源来生产增值化学品。生物质作为一种来源丰富的可再生有机碳源,可用于转化制备许多有价值的化工产品。其中可通过乳酸氧化制备的丙酮酸备受关注,可用于制备各种工业产品,如香水、食品添加剂、药品等。金属有机框架材料(MOF)由于其高度多样化的结构、高比表面积和可调节的孔径而成为近10年来备受关注的材料,可用于制备活性催化剂或载体。在本工作中,MOF衍生的钒基碳材料被用于催化乳酸乙酯有氧氧化为丙酮酸乙酯。在最佳条件下,MOF-5衍生的钒催化剂的乳酸乙酯转化率为95.72%,丙酮酸乙酯选择性为67.10%。经过多次循环,该催化剂具有良好的稳定性。实验及表征结果表明:V^(5+)/V^(4+)物种的比例,而非孔道结构,是决定催化性能的关键。

球囊霉素相关土壤蛋白对钒钛磁铁尾矿生态环境的修复效果研究

为探讨丛枝菌根真菌(Arbuscular mycorrhizal fungi,AMF)释放的球囊霉素相关土壤蛋白(Glomalin related soil protein,GRSP)对钒钛磁铁尾矿生态环境的修复作用,开展了紫花苜蓿室内培养实验,通过外源施加不同形态及不同剂量的球囊霉素相关土壤蛋白,研究了其对钒钛磁铁尾矿养分环境、团聚结构、重金属活性及紫花苜蓿生长的影响。结果表明:施加GRSP后钒钛磁铁尾矿养分环境得到明显改善,EEG使钒钛磁铁尾矿中速效磷含量增加了19.7%~60.1%;TG效果则更加显著,碱解氮含量和速效磷含量分别增加了12.2%~58.9%和44.7%~111.3%;此外,外源施加TG后钒钛磁铁尾矿团聚结构的稳定性会显著增加,大团聚体占比、平均重量直径和几何重量直径分别增加了29.36%~114.63%、4.76%~15.87%和9.26%~16.67%,提高了钒钛磁铁尾矿对重金属及养分的固持能力;两种形态GRSP对钒钛磁铁尾矿中不同重金属作用有所差异,EEG能显著降低Cu有效性,DTPA提取态Cu含量降低16.7%,TG主要钝化Cr,DTPA提取态Cr含量减少了72.6%。此外,柠檬酸钠的加入在一定程度上抑制了紫花苜蓿的生长。综合分析表明,球囊霉素相关土壤蛋白可以改变钒钛磁铁尾矿重金属活性、提高团聚体稳定性并改善养分环境,为尾矿矿区生态修复提供了理论依据。