Critical evaluation and thermodynamic modeling of the Fe–V–O (FeO–Fe2O3–VO–V2O3–VO2–V2O5) system

Du, Wei-Tong; Jung, In‐Ho

doi:10.1016/j.calphad.2019.101682

Cited by 20 publications

(8 citation statements)

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“…The APT results also show that several gangue-related impurities indeed get captured in nanosized metastable oxides, possibly on the way to the spinel phase formation. The observed ratio of O to metal ions is unlike reported for any typical Fe-rich oxide, including those in the Fe-V-O system 49 . A Fe2O oxide mineral was reported to be stable at high pressures such as those encountered in the Earth's core 50,51 , and off-stoichiometric amorphous Fe-rich oxides with similar compositions have been reported in tribological layers 52 .…”

Section: Structure and Composition Analysis At Near-atomic Scalecontrasting

confidence: 77%

Influence of Microstructure and Atomic-Scale Chemistry on Iron Ore Reduction with Hydrogen at 700°C

et al. 2020

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With 1.85 billion tons produced per year, steel is the most important material class in terms of volume and environmental impact. While steel is a sustainability enabler, for instance through lightweight design, magnetic devices, and efficient turbines, its primary production is not. For 3000 years, iron has been reduced from ores using carbon. Today 2.1 tons CO2 are produced per ton of steel, causing 30% of the global CO2 emissions in the manufacturing sector, which translates to 6.5% of the global CO2 emissions. These numbers qualify iron-and steel-making as the largest single industrial greenhouse gas emission source. The envisaged future industrial route to mitigate these CO2 emissions targets green hydrogen as a reductant. Although this reaction has been studied for decades, its kinetics is not well understood, particularly during the wüstite reduction step which is dramatically slower than the hematite reduction. Many rate-limiting factors of this reaction are set by the micro-and nanostructure as well as the local chemistry of the ores. Their quantification allows knowledge-driven ore preparation and process optimization to make the hydrogen-based reduction of iron ores commercially viable, enabling the required massive CO2 mitigation to ease global warming. Here, we report on a multi-scale structure and composition analysis of iron reduced from hematite with pure H2, reaching down to near-atomic scale. The microstructure after reduction is an aggregate of nearly pure iron crystals, containing inherited and acquired pores and cracks. Crucial to the reduction kinetics, we observe the formation of several types of lattice defects that accelerate mass transport inbound (hydrogen) and outbound (oxygen) as well as several chemical impurities within the Fe in the form of oxide islands that were not reduced. With this study, we aim to open the perspective in the field of carbon-neutral iron production from macroscopic processing towards a better understanding of the underlying microscopic reduction mechanisms and kinetics.

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Section: Structure and Composition Analysis At Near-atomic Scalecontrasting

confidence: 77%

Influence of Microstructure and Atomic-Scale Chemistry on Iron Ore Reduction with Hydrogen at 700°C

et al. 2020

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“…Therefore, a large number of compounds and several solid solutions, including spinel, wu ¨stite, and corundum, are stable over a wide range of temperatures and oxygen partial pressures in the Fe-V-O system. 17 Recently, Du and Jung 18 critically optimized the solid and liquid solutions of the Fe-V-O system using compound energy formalism (CEF) 19 and a modified quasi-chemical model (MQM), 20 respectively. In the optimization, the Fe 3 O 4 -FeV 2 O 4 spinel phase was modeled to investigate the vanadium cation V 3+ distribution between tetrahedral and octahedral sublattices.…”

Section: Thermodynamic Simulation Of Composition Changes During the Pilot Testsmentioning

confidence: 99%

Oxidation Mechanism During Pyrometallurgical Vanadium Extraction Process Using CO2-Containing Gas

You

et al. 2021

JOM

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In the present work, the oxidation characterization and mechanism of vanadium extraction by bottom injection of CO 2 were investigated based on laboratory experiments and pilot tests. In addition, variations of the compositions of all stable phases including gas, hot metal, slag, and spinel during the vanadium extraction process through injecting pure O 2 , 15 vol.% CO 2 -85 vol.% O 2 , and 30 vol.% CO 2 -70 vol.% O 2 gases were simulated based on the recently optimized vanadium-containing oxides database stored in FactSage software. As a consequence, oxidation of vanadium by CO 2 was an apparent secondorder reaction. Transformation of dissolved vanadium to vanadium-containing spinel can be enhanced with bottom injection of 15 vol.% CO 2 -85 vol.% O 2 into the hot metal. With the increase of bottom injected CO 2 from 15 vol.% to 30 vol.%, the oxidation of dissolved vanadium could be restrained due to the reduction of oxygen potential originating from partial replacement of O 2 by CO 2 .

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“…4 Typically, roasted vanadium slag is regarded as a V 2 O 5 -CaO-MgO-Fe 2 O 3 -Al 2 O 3 -MnO-Cr 2 O 3 -TiO 2 multiple oxide system, and the CaO-MgO-V 2 O 5 ternary system is a fundamental and essential subsystem. 5 The incomplete exact phase relationship and thermodynamic properties of the CaO-MgO-V 2 O 5 system are necessary for an in-depth understanding of the calcium roasting of the vanadium-contained BOF slag.…”

Section: Introductionmentioning

confidence: 99%

“…The design and optimization of the salts roasting process at high temperatures are a key factor in this development process and requires reliable thermochemistry databases 4 . Typically, roasted vanadium slag is regarded as a V 2 O 5 –CaO–MgO–Fe 2 O 3 –Al 2 O 3 –MnO–Cr 2 O 3 –TiO 2 multiple oxide system, and the CaO–MgO–V 2 O 5 ternary system is a fundamental and essential subsystem 5 . The incomplete exact phase relationship and thermodynamic properties of the CaO–MgO–V 2 O 5 system are necessary for an in‐depth understanding of the calcium roasting of the vanadium‐contained BOF slag.…”

Section: Introductionmentioning

confidence: 99%

Double pyrovanadates CaMgV₂O₇: Formation mechanism, phase structure, and thermodynamic properties

et al. 2022

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A double pyrovanadate CaMgV 2 O 7 sample was synthesized via a facile solidstate route under an air atmosphere. The nonequilibrium formation pathways of the CaMgV 2 O 7 were investigated via powder X-ray diffraction. A multistep reactions path (metavanadates-pyrovanadates-double pyrovanadate CaMgV 2 O 7 ) was proposed to describe the formation of the CaMgV 2 O 7 considering the thermodynamic and kinetic factors. The cell unit parameters of the CaMgV 2 O 7 sample indicated the crystallization according to a monoclinic system with space group P12/c1( 14), and the lattice parameters of a = 6.756 Å, b = 14.495 Å, c = 11.253 Å, β = 99.12, and V = 108.806 Å 3 . X-ray photoelectron spectroscopy also confirmed the +5 oxidation state vanadium in CaMgV 2 O 7 . The endothermic effects at 1033 and 1143 K were related to the incongruent melting and liquidus temperatures of CaMgV 2 O 7 , respectively. The comprehensive thermodynamic properties of CaMgV 2 O 7 were established in both low-and high-temperature regions, utilizing a physical property measurement system and multi-hightemperature calorimetry (96 lines). The heat capacity (200 J mol K −1 ) and entropy (198 J mol K −1 ) at 298.15 K were computed based on the low-temperature heat capacity values, and the enthalpy of formation at 298.15 K was also estimated. The fitted high-temperature capacity can be used to obtain the changes in the enthalpy, entropy, and Gibbs free energy. This study is part of building a reliable thermodynamic database of the CaO-MgO-V 2 O 5 system.

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Critical evaluation and thermodynamic modeling of the Fe–V–O (FeO–Fe2O3–VO–V2O3–VO2–V2O5) system

Cited by 20 publications

References 57 publications

Influence of Microstructure and Atomic-Scale Chemistry on Iron Ore Reduction with Hydrogen at 700°C

Influence of Microstructure and Atomic-Scale Chemistry on Iron Ore Reduction with Hydrogen at 700°C

Oxidation Mechanism During Pyrometallurgical Vanadium Extraction Process Using CO2-Containing Gas

Double pyrovanadates CaMgV₂O₇: Formation mechanism, phase structure, and thermodynamic properties

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Critical evaluation and thermodynamic modeling of the Fe–V–O (FeO–Fe2O3–VO–V2O3–VO2–V2O5) system

Cited by 20 publications

References 57 publications

Influence of Microstructure and Atomic-Scale Chemistry on Iron Ore Reduction with Hydrogen at 700°C

Influence of Microstructure and Atomic-Scale Chemistry on Iron Ore Reduction with Hydrogen at 700°C

Oxidation Mechanism During Pyrometallurgical Vanadium Extraction Process Using CO2-Containing Gas

Double pyrovanadates CaMgV2O7: Formation mechanism, phase structure, and thermodynamic properties

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Double pyrovanadates CaMgV₂O₇: Formation mechanism, phase structure, and thermodynamic properties