V2 O3 Research Articles

Partition of valuable components between slag and metal in the blast furnace operating with high chromium, vanadium, titanium, magnetite ores

In order to master the partition between metal and slag for high chromium vanadium titanium magnetite in ironmaking process, the same batch of sinter, pellet, hot metal and slag were investigated mainly from two viewpoints of phase composition change and distribution of valuable components in this study. Chemical analysis, XRD and SEM-EDS analysis, material balance and distribution of valuable components reveal that the total input-output amounts of valuable components are nearly balanced under the stable operation condition. 98.60% of iron, 86.71% of vanadium, 83.73% of chromium and only 6.48% of titanium have passed to hot metal. The distribution of titanium and silicon between hot metal and slag was investigated, which is in accordance with the previous studies in the laboratory condition. The phase composition change process of vanadium is V2 O3 → [V]. The reduction process of chromium oxide is Cr2 O3 → [Cr]. The titanium oxide is partially reduced into the hot metal in the hearth by the reaction: TiO2 → [Ti], then the dissolved titanium can easily react with C and N2 forming Ti(C,N).

Effect of Nitrogen Substitution in V2 O3 on the Metal-Insulator Transition.

The effect of N-doping on the paramagnetic-antiferromagnetic transition associated with the metal-insulator (M-I) transition of V2 O3 at 150 K has been studied in bulk samples as well as in nanosheets. The magnetic transition temperature of V2 O3 is lowered to ∼120 K in the N-doped samples. Electrical resistivity data also indicate a similar lowering of the M-I transition temperature. First-principles DFT calculations reveal that anionic (N) substitution and the accompanying oxygen vacancies reduce the energy of the high-temperature metallic corundum phase relative to the monoclinic one leading to the observed reduction in Nèel temperature. In the electronic structure of N-substituted V2 O3 , a sub-band of 2p states of trivalent anion (N) associated with its strong bond with the vanadium cation appears at the top of the band of O(2p) states, the 3d-states of V being slightly higher in energy. Its band gap is thus due to crystal field splitting of the degenerate d-orbitals of vanadium and superexchange interaction, which reduces notably (ΔEg =-0.4 eV) due to their hybridization with the 2p states of nitrogen. A weak magnetic moment arises in the monoclinic phase of N-substituted V2 O3 with O-vacancies, with a moment of -1 μB /N localized on vanadium atoms in the vicinity of oxygen vacancies.

Thermodynamic analysis of the metal-insulator transitions in V2O3 alloy systems

An overview is presented concerning the entropies (ΔS) and enthalpies (ΔH) associated with metal-insulator transitions in the (V1−x M x )2O3 M=Al, Cr, Ti systems, 0⩽x⩽0·12 and in non-stoichiometric V2(1 −y )O3, 0⩽y⩽0·01. The recent literature and new data are analyzed with respect to gradiations in ΔH and ΔS withx ory, and their implications concerning the mechanism of the transitions. A revised phase diagram is presented.

CRYSTAL AND MOLECULAR STRUCTURE OF THE DIOXO BIS (8-QUINOLINOLATO) VANADIUM(V) ION AND ITS RELATIONS WITH THE MIXED VALENCE μ-OXO-[OXOBIS(8-QUINOLINOLATO) VANADIUM(V)][OXO BIS (8-QUINOLINOLATO) VANADIUM(IV)] ION

Abstract The crystal structure of NBu4 + VO2 Q2 − (Q=8-quinolinol anion) has been determined from three dimensional X-ray data collected with MoKα radiation (λ=0.71069 A). Crystal data are as follows: tetragonal, space group I 4 2 d, a=19.004(5), c=19.475(8)A, Z=8. The structure has been refined by full matrix least squares methods, using 1265 independent reflections to a conventional weighted R factor of 0.082. The VO2 Q2 − anion exhibits a C2 symmetry with a cis VO2 group (O–V–O angle: 105°). The nitrogen atom of the 8-quinolinolate ligand is trans to an oxo oxygen and the ligand oxygen atoms are trans to each other. The reaction of VO2 Q2 − upon VOQ2 giving the mixed valence V2 O3 Q4 − ion is studied and a structure is proposed for the latter, which would explain the absence of interaction between the two vanadium atoms.