A method for recovery of iron,titanium,and vanadium from vanadium-bearing titanomagnetite

An innovative method for recovering valuable elements from vanadium-bearing titanomagnetite is proposed. This method involves two procedures： low-temperature roasting of vanadium-bearing titanomagnetite and water leaching of roasting slag. During the roasting process, the reduction of iron oxides to metallic iron, the sodium oxidation of vanadium oxides to water-soluble sodium vanadate, and the smelting separation of metallic iron and slag were accomplished simultaneously. Optimal roasting conditions for iron/slag separation were achieved with a mixture thickness of 42.5 mm, a roasting temperature of 1200°C, a residence time of 2 h, a molar ratio of C/O of 1.7, and a sodium carbonate addition of 70 wt%, as well as with the use of anthracite as a reductant. Under the optimal conditions, 93.67% iron from the raw ore was recovered in the form of iron nugget with 95.44% iron grade. After a water leaching process, 85.61% of the vanadium from the roasting slag was leached, confirming the sodium oxidation of most of the vanadium oxides to water-soluble sodium vanadate during the roasting process. The total recoveries of iron, vanadium, and titanium were 93.67%, 72.68%, and 99.72%, respectively.

Extraction of vanadium from molten vanadium bearing slag by oxidation with pure oxygen in the presence of CaO

A novel process of vanadium extraction from vanadium slag in its molten state was conducted at the laboratory scale by oxidation with pure oxygen in the presence of CaO. The effect of mass ratio of CaO to V2O5 on the recovery of vanadium was studied. The sintered samples were leached by H2SO4 solution and characterized by XRD, XPS, SEM and EDS techniques. Compared with the roasting process, the energy saving effect of the proposed process was also discussed. The results showed that vanadium-rich phases were formed and vanadium mainly existed in the forms of CaV2O5 and Ca2V2O7. The formation mechanism of calcium vanadates in the molten vanadium bearing slag was explained. The XRD and XPS results implied that there was a limit to the oxidation reaction of V(IV) to V(V) under the high temperatures even though oxygen-supply was sufficient. An increase in the CaO content led to an increase in the formation of Ca2V2O7. About 90%of the vanadium recovery was obtained under optimal experiment conditions (mass ratio of CaO to V2O5 of 0.6, particle size 120 to 150μm, leaching temperature 90 °C, leaching time 2 h, H2SO4 concentration 20%, liquid to solid ratio 5:1 mL/g, stirring speed 500 r/min). The energy of 1.85×106 kJ could be saved in every 1000 kg of vanadium bearing slag using the proposed process from the theoretical calculation results. Recovery of vanadium from the molten vanadium bearing slag and utilisation of its heat energy are important not only for saving metal resources, but also for energy saving and emission reduction.

Kinetic modeling of adsorption of vanadium and iron from acid solution through ion exchange resins

This study assessed the adsorption process and the reaction kinetics involved in the selective recovery of vanadium from an acid solution containing iron as an impurity.Four commercial resins were studied:Lewatit^(®)MonoPlus TP 209 XL,Lewatit^(®) TP 207,Dowex^(TM)M4195(chelating resin)and Lewatit^(®) MonoPlus S 200 H(strong cationic exchange resin).To investigate the effect of time on the adsorption process,batch experiments were carried out using the following initial conditions:pH 2.0,298 K,and a proportion of 1 g of resin to 50 mL of solution.The variation of pH over time was analyzed.Chelating resin released less H+ions as the adsorption occurred,resulting in a lower drop of pH when compared to S 200 H resin.Ion adsorption by the resins was also evaluated through FT-IR and SEM−EDS before and after the experiments.Among the evaluated kinetic models(pseudo-first order,pseudo-second order,Elovich and intraparticle diffusion models),the pseudo-second order model best fits the experimental data of the adsorption of vanadium and iron by all of the four resins.M4195 resin showed the highest recovery of vanadium and the lowest adsorption of iron.Kinetic data,which are fundamental to industrial processes applications,are provided.

Utilization of waste vanadium-bearing resources in the preparation of rare-earth vanadate catalysts for semi-hydrogenation of α,β-unsaturated aldehydes

Recycling industrial solid waste not only saves resources but also eliminates environmental concerns of toxic threats.Herein,we proposed a new strategy for the utilization of petrochemical-derived carbon black waste,a waste vanadium-bearing resource(V>30000 ppm(10−6)).Chemical leaching was employed to extract metallic vanadium from the waste and the leachate containing V was used as an alternative raw material for the fabrication of vanadate nanomaterials.Through the screening of various metal cations,it was found that the contaminated Na^(+)during the leaching process showed strong competitive coordination with the vanadium ions.However,by adding foreign Ce^(3+)and Y^(3+)cations,two rare-earth vanadates,viz.,flower-like CeVO_(4)and spherical YVO_(4)nanomaterials,were successfully synthesized.Characterization techniques such as scanning electron microscopy,transmission electron microscopy,X-ray diffraction,energy-dispersive X-ray spectroscopy,Fourier-transform infrared,and N2 physisorption were applied to analyze the physicochemical properties of the waste-derived nanomaterials.Importantly,we found that rare-earth vanadate catalysts exhibited good activities toward the semi-hydrogenation ofα,β-unsaturated aldehydes.The conversion of cinnamaldehyde and cinnamic alcohol selectivity were even higher than those of the common CeVO_(4)prepared using pure chemicals(67.2%vs.27.7%and 88.4%vs.53.5%).Our work provides a valuable new reference for preparing vanadate catalysts by the use of abundant vanadium-bearing waste resources.

Characterization strategy of polymeric transition metal species transformation for high-purity metal recovery

The aqueous metal species with similar chemical properties are usually extracted together,limiting deep separation for high-purity metal.However,rare attention has been paid to metal speciation characterization and transformation during separation.Herein,the hydrolysis evolution of polymeric metal species was investigated systematically by electrospray ionization time-of-flight mass spectrometry(ESI-TOF-MS).The transformation evolutions were visualized with respect to characteristic vanadium species(V_(1),V_(2),V_(3),V_(4) and V_(10)),chromium species(Cr_(1) and Cr_(2)),tungsten(W_(1),W_(2),W_(4),W_(6) and W_(10))and molybdenum(Mo_(1),Mo_(2) and Mo_(4))species.The key characteristics(such as specfic pHs and concentrations)for speciation variation were revealed.The polymerization behavior of several transition metals can be semiquantitative characterized by this strategy.The sufficient speciation transformation provides a solid base for metal speciation chemistry,and guides further development of high-purity metal recovery.