钒钛物料中钒钛化学物相分析现状及最新进展

主要概述了钒钛炉渣原料中价态钒(V2+,V3+,V4+,V5+),低价钛(Ti 2+,Ti 3+),金属钒(MV),氮化钒(VN),碳化钒(VC),碳化钛(TiC),氮化钛(TiN)及钢铁材料里固溶钒(Vsol),氮化钒(VN),碳化钒(VC),固溶钛(Tisol),碳化钛(TiC),氮化钛(TiN)等的化学物相分析的现状流程及最新进展,为从事钒钛化学物相分析方法研究者提供了参考依据。     

贵州三穗县钒矿石及矿渣微量元素综合利用评价

目的：探讨钒矿及矿渣中的微量元素含量,以便为钒矿石和矿渣的有效利用提供重要参考。方法采用ICP-MS对钒矿石中的微量元素进行分析,并对钒矿石和矿渣中的微量元素利用进行了评价。结果钒矿中的钒利用率仅为64.9％,矿渣中的V、 Cr、 Zn、 Mo、 Cd和U的含量很高。结论分析认为, V、 Cr、 Zn、 Mo、 Cd和U可能会对环境造成一定的影响。     

电热蒸发进样—等离子体原子发射光谱中钒和钛的蒸发机理研究

自1974年Nixon报道钽丝电热蒸发作为ICP-AES进样技术以来,这一技术已引起了人们的极大兴趣,受到越来越广泛的重视。电热蒸发(ETV)-ICP-AES是一种将蒸发和激发分步进行的联用技术。石墨是目前普遍使用的蒸发器材料。然而,在高温下某些元素和石墨材料可以发生碳化反应,形成热稳定的碳化物,使分析物蒸发不完全或根本不蒸发,从而影响分析结果的灵敏度和准确性。为了解决这一问题,我们曾提出了以聚四氟乙烯(PTFE)悬浮体为氟化剂,氟化辅助ETV-ICP-AES直接测定粉煤标样中钒和钛的新方法,其检出限     

Asymmetric cyanohydrin synthesis using heterobimetallic catalysts obtained from titanium and vanadium complexes of chiral and achiral salen ligands

Titanium(IV)(salen) and vanadium(V)(salen) complexes are both known to form catalysts for asymmetric cyanohydrin synthesis. When a mixture of titanium and vanadium complexes derived from the same or different salen ligands is used for the asymmetric addition of trimethylsilyl cyanide to benzaldehyde, the absolute configuration of the product and level of asymmetric induction can only be explained by in situ formation of a catalytically active heterobimetallic complex, and is not consistent with two monometallic species acting cooperatively. Combined use of complexes containing chiral and achiral salen ligands demonstrates that during the asymmetry inducing step of the mechanism, the aldehyde is coordinated to the vanadium rather than the titanium ion. The titanium complexes also catalyse the asymmetric addition of ethyl cyanoformate to aldehydes, a reaction in which vanadium(V)(salen) complexes are not active. For this reaction, use of a mixture of titanium and vanadium(salen) complexes results in a complete loss of catalytic activity, a result which again can only be explained by in situ formation of a heterometallic complex. Both the titanium and vanadium based catalysts also induce the asymmetric addition of potassium cyanide/acetic anhydride to aldehydes. For this reaction, combined use of chiral and achiral complexes indicates that during the asymmetry inducing step of the mechanism, the aldehyde is coordinated to titanium rather than vanadium, a result which contrasts with the observed results when trimethylsilyl cyanide is used as the cyanide source.     

Determination of small amounts of titanium in pure molybdenum,tungsten, vanadium and their oxides after separation on silica gel

A new method for the separation of titanium from molybdenum, tungsten and vanadium is described, based on sorption of the titanium complex with hydrogen peroxide on silica gel under dynamic conditions. The eluted titanium is determined spectrophotometrically with diantipyrylmethane. The method can be applied to the determination of small amounts of titanium in tungsten, molybdenum and vanadium metals and in their oxides.     

NH3 TPD study and thermal behaviour of vanadium-exchanged titanium phosphates as catalysts

The ion exchange technique was employed for the preparation of VO²⁺ modified titanium phosphates as catalysts for the selective reduction of NO with NH₃. The samples were prepared by contacting with a vanadyl sulphate solution different precursor materials, amorphous, crystalline or sodium half exchanged titanium phosphate. The vanadium contents of modified phosphates were in the range 0.08–2.3 wt%. XRD and thermal analysis TG/DTA showed that vanadium loading does not cause structural modification in hydrogen titanium phosphate. A vanadyl containing phase was obtained when half sodium titanium phosphate was employed. The NH₃ TPD measurements indicated the presence of a wide distribution of NH₃ adsorbing sites with medium-high strength. Catalytic activity measurements were performed under dilute conditions. It was found that the presence of vanadium even in low amounts strongly promote the catalytic activity.     

Separation of vanadium-48 from a deuteron-irradiated TiO2 target

The influence of perchloric acid and hydrogen peroxide concentrations on the elution rates of vanadium and titanium from Dowex-50W X 8 resin was studied. The amounts of perchloric acid and of hydrogen peroxide were adjusted to provide an optimum eluent for the separation of vanadium from the irradiated titanium (TiO₂) target.     

ICP-OES测定钒矿石中五氧化二钒的测量不确定度评定

介绍了电感耦合等离子体发射光谱法(ICP-OES)测定钒矿石中五氧化二钒测重不确定度的评定万法.建立了测量过程中各不确定度分量的数学模型,对不确定度来源进行了分析,并对不确定度分量进行量化.当钒矿石中五氧化二钒含量为0.419％时,其扩展不确定度为0.0070％(k=2).     

用混合熔剂熔融制样-XRFS法分析铁矿石方法改进的探讨

针对XRFS法分析铁矿石时存在的总铁量及硫量测定结果的不准确问题,作了进一步试验并对方法提出了修改。其要点是采用了加入含钴的四硼酸锂和碳酸锂的混合熔剂熔融试样,并对熔融温度及时作了规定,采用钴的谱线作内标,以及根据总铁量的高低分别采用两条工作曲线。此外,对同时含钒及钛的试样,采用校正方法消除其相互间的干扰,按修改后的方法分析铁矿石试样,结果的准确度和精密度均达到规定要求。     

A radiochemical method of separation of carrier-free vanadium from scandium and bulk amount of titanium

A method for the separation of carrier-free vanadium from scandium and bulk amount of titanium has been developed. Vanadium has been produced through the reaction^natTi(d,n)^48,49V with 8 MeV deuterons from the Variable Energy Cyclotron, Calcutta. The separation is performed with Dowex 1×8, 50–100 mesh fluoride from anion exchange resin which retains all the scandium and titanium with 4.5M hydrofluoric acid as eluent, while vanadium(V) is easily eluted. The chemical yield of vanadium was >85%.     

Thermodynamics of titanium and vanadium reduction in non-aqueous environment calculated at various levels of theory

Reduction of titanium and vanadium compounds is a process accompanying the activation of coordinative olefin polymerization catalysts. Four density functional theory (DFT) functionals, coupled cluster with single, double, and perturbative triple excitations method CCSD(T) as well as complete active-space second-order perturbation theory method CASPT2 with a complete active-space self-consistent field CASSCF reference wave function were applied to investigate the thermodynamics of titanium and vanadium reduction. The performance of these theoretical methods was assessed and compared with experimental values. The calculations indicate that vanadium(IV) chloride is more easily reduced by trimethylaluminum than the corresponding titanium compound; the energies of reaction calculated at the CCSD(T) level are equal -57.21 and -33.10 kcal/mol, respectively. The calculations deal with the redox reactions of metal chlorides in the gas phase, rather than solvated ions in the aqueous solution. This approach may be more appropriate for olefin polymerization, usually carried out in nonpolar solvents.     

Photometric titration of titanium(III) with iron(III)

An oxidimetric titration of titanium(III) with iron(III) with a photometric end-point is proposed. Acetylacetone was used to obtain an intensely coloured titanium(III) complex; titanium(III) was formed by prereduction with chromium(II) or vanadium(II). Amounts of titanium down to 35 μg were determined with fairly good accuracy and precision. Few common elements interfere.     

First-derivative spectrometric analysis of mixtures of peroxo complexes of titanium,vanadium, and molybdenum for respective metals

The application of first-derivative spectrometry to the simultaneous determination of titanium and vanadium; titanium and molybdenum; and vanadium and molybdenum in their mixtures with varying mass ratios has been described with hydrogen peroxide as color developing reagent. At a first-derivative isosbestic point for the peroxo complex of one constituent, the derivative absorbance of the other constituent is read and used for quantitation. The procedure does not require the solution of simultaneous equations. The first-derivative spectrometry is also feasible at 450.0 nm for the selective determination of titanium in the presence of vanadium, molybdenum, and tungsten.     

Analysis of niobium alloys

An ion-exchange method was applied to the analysis of synthetic mixtures representing various niobium-base alloys. The alloying elements which were separated and determined include vanadium, zirconium, hafnium, titanium, molybdenum, tungsten and tantalum. Mixtures containing zirconium or hafnium, tungsten, tantalum and niobium were separated by means of a single short column. Coupled columns were employed for the resolution of mixtures containing vanadium, zirconium or titanium, molybdenum, tungsten and niobium. The separation procedures and the methods employed for the determination of the alloying elements in their separate fractions are described.     

电感耦合等离子体原子发射光谱法(ICP-OES)测定含钒尾渣中钒的含量

以氢氟酸、硝酸消解样品,然后加入硫酸络合钛避免其在低酸度介质中水解,并且加热至产生三氧化硫烟以驱赶氢氟酸,以水稀释定容后采用电感耦合等离子体原子发射光谱法（ICP-OES）直接测定含钒尾渣中钒的含量。实验考察了在共存含有铁、钛、铝、铬、锰、钒等元素的含钒尾渣复杂基体中,基体效应、光谱干扰以及背景噪音等影响因素对钒测定的干扰,方法通过优选元素分析谱线、背景校正区域以及光谱仪工作条件,并且采用基体匹配法和同步背景校正法相结合的方式,消除了构成复杂且变化无常的样品基体对测定的影响。结果表明,方法可用于测定0.01%~6.0%的钒,并且样品基体在含20%~40%铁,5%~30%钛时,铝、铬、锰、钠、硅、钙、镁各元素1%~10%的变化对测定无影响,检测下限可达0.0009%;精密度RSD〈3%,加标回收率94%~106%,与高锰酸钾氧化-硫酸亚铁铵滴定化学分析法的测定结果对照一致。     

5-Br-PADAP光度法测钒钛磁铁矿中钒的不确定度评定

5-Br-PADAP光度法是测钒钛磁铁矿中钒的主要方法之一。根据其分析过程的操作步骤确定了其影响因素。建立数学模型,并根据数学模型把不确定度分解为称样质量、溶液含量、钒标准工作曲线和重复测定引入的各不确定度,对影响测量结果的各个分量进行了分析评定和计算。结果表明,钒的标准工作曲线的建立是影响样品分析误差的重要因素。     

Leaching behavior of uranium and vanadium using strong sulfuric acid from Korean black shale ore

The present scientific study focused on leaching behavior of uranium and vanadium from Korean domestic ore. The leaching process experimental conditions optimized for uranium and vanadium metals recovery from Korean domestic ore and developed the basic experimental procedures such as time, particle size, acid influence, temperature effect and pulp density (PD) behavior. Acid influence on leaching process was tested and noted that 2.0 M sulfuric acid concentration is the optimized conditions for present study. The time influence on leaching process was observed and its optimized 2 h for complete leaching process. The temperature influence tested and optimized the 80 °C for complete leaching process and PD is 50 % (wt%). The bench scale experiments developed in a laboratory and tested in pilot level each batch 100 kg of ore sample.     

The separation of titanium from vanadium and molybdenum by cupferron solvent extraction

The isolation of small amounts of titanium from vanadium and molybdenum before the spectrophotometric determination of titanium as the “pertitanate” complex has been achieved by a. solvent extraction procedure using cupferron and chloroform at pH 6 in the presence of EDTA.     

Copolymerization of ethylene and propylene catalyzed by magnesium chloride supported vanadium/titanium bimetallic Ziegler-Natta catalysts

Magnesium chloride supported vanadium/titanium bimetallic Ziegler-Natta catalysts with di-i-butyl phthalate as internal donor for copolymerization of ethylene and propylene were prepared.The effects of reaction temperature, ethylene/propylene molar ratio,aluminium/vanadium（Al/V）molar ratio and titanium/vanadium molar ratio on the catalytic activity were investigated.The molecular weight,molecular weight distribution,sequence composition and crystallinity of the products were measured by gel permeation chromatography,¹³C-NMR and differential scanning calorimetry analysis, respectively.In comparison to the vanadium and titanium catalysts,the bimetallic catalyst showed higher catalytic activity and better copolymerization performance.The obtained ethylene/propylene copolymers have high molecular weight （10⁵）,broad molecular weight distribution,high propylene content with random or short blocked sequence structures （r_Er_P=1.919）,low melting temperatures and low crystallinities（X_c<20%）.     

Solvent extraction of metals with hydroxamic acids

Solvent extraction with hydroxamic acids has been investigated. with comparison of aliphatic and aromatic reagents for the extraction of iron, copper, cobalt and nickel. Caprylohydroxamic acid has been evaluated for use in extraction systems for titanium, vanadium, chromium, molybdenum and uranium, both in terms of acidity of aqueous phase and oxidation state of the metal. It has been established that caprylohydroxamic acid in 1-hexanol is a suitable extractant for the removal of titanium(IV), vanadium(V), chromium(VI), molybdenum(VI) and uranium(VI) from 6M hydrochloric acid.