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.

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.