Kinetics of reduction of iron oxides by H2

Pineau, Annye; Kanari, Ndue; Gaballah, I.

doi:10.1016/j.tca.2005.10.004

Cited by 405 publications

(179 citation statements)

References 22 publications

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“…6) Furthermore, the kinetics of H 2 utilization in the reduction reaction, one of the major reactions inside the BF, have been also reported for various starting materials such as hematite (Fe 2 O 3 ), [7][8][9][10] magnetite (Fe 3 O 4 ), 11) and wüstite (hereinafter referred to as 'FeO') 12,13) -the constituent phases of iron ore charged into the BF. However, in addition, the effects of impurities such as SiO 2 and CaO on the reducibility of iron ores can be expected to significantly differ under H 2 than under CO.…”

Section: Introductionmentioning

confidence: 99%

Influence of CaO and SiO2 on the Reducibility of W^|^uuml;stite Using H2 and CO Gas

et al. 2012

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CaO-(0-20 mass%) and SiO2-containing (0-30 mass%) wüstite ('FeO') compacts were isothermally reduced at 1 273 K under CO and H2 gas. Prior to reduction, the phase of dicalcium ferrite (Ca2Fe2O5) and fayalite (Fe2SiO4) was equilibrated with 'FeO' at 1 273 K under 50%CO/50%CO2 and identified using X-ray diffraction and scanning electron microscopy. The rate of reduction for CaO-containing 'FeO' compacts under both H2 and CO increased up to the vicinity of 2.5 mass% CaO, and then decreased with higher CaO dependent on the formation of an intermediate phase of dicalcium ferrite. For SiO2-containing 'FeO', the rate decreased with SiO2 additions. When the dense fayalite is present reduction using CO was limited, while considerable reduction was observed using H2. The reduction was affected by three distinct reduction mechanisms of interfacial chemical reaction, gaseous mass transport, solid state diffusion of oxygen or a combination of these individual mechanisms termed the mixed control. The contribution of each mechanism with the content of CaO or SiO2 affecting the reduction behavior was determined. The compact porosity increased when CaO was added to approximately 2.5 mass% and subsequently decreased with higher CaO, but continuously decreased with SiO2 additions. The ratio of the effective diffusivity (De) to molecular interdiffusivity (D) was highest at the vicinity of 2.5 mass% CaO and thus the maximum reduction rate was obtained when the porosity was highest.

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Section: Introductionmentioning

confidence: 99%

Influence of CaO and SiO2 on the Reducibility of W^|^uuml;stite Using H2 and CO Gas

et al. 2012

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“…[20][21][22][23][24][25][26][27][28][29][30][31][32] Moreover, the gaseous reduction of iron oxides to metal iron by hydrogen gas has also been recognized as an environmental friendly way. [33][34][35][36] However, high cost of hydrogen production is still a challenge for iron and steel industry. [34][35][36] On the contrary, the inherent advantage of the electrochemical process is its environmental compatibility since the electron is a ''clean/green'' reagent.…”

Section: Introductionmentioning

confidence: 99%

“…[33][34][35][36] However, high cost of hydrogen production is still a challenge for iron and steel industry. [34][35][36] On the contrary, the inherent advantage of the electrochemical process is its environmental compatibility since the electron is a ''clean/green'' reagent. [37][38][39] Li et al [17] and Haarberg et al [40] successively obtained pure iron metal from iron(III) oxide by the direct electroreduction/electrodeposition routes in molten salts at temperature >1073 K (800°C).…”

Section: Introductionmentioning

confidence: 99%

Electroreduction of Iron(III) Oxide Pellets to Iron in Alkaline Media: A Typical Shrinking-Core Reaction Process

Zou

et al. 2015

Metall Mater Trans B

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Low temperature electrochemical reduction of iron(III) oxide to iron in a strongly alkaline solution has been systematically investigated in this article. The facile electrochemical process was carried out in 50 to 70 wt pct aqueous NaOH solution at 383 K (110°C) and 1.7 V. The preformed spherical Fe 2 O 3 pellets with porous structures were used directly as precursors for the electrolytic production of iron. The influences of the experimental parameters on the electroreduction process and the characteristics of the iron products as well as the reaction mechanisms were investigated. The results show that the precursor's pre-sintering process and the concentration of NaOH aqueous electrolyte have significant influences on the electroreduction process. The electroreduction-generated spherical metallic iron layer comprising dendritic iron crystals is first formed on the surface of Fe 2 O 3 pellet precursor and then extends gradually into the pellet's interior along the radial direction. The electroreduction process is confirmed to be a typical shrinking-core reaction process. The direct solid state electroreduction mechanism and the dissolution-electrodeposition mechanism coexist in the electrochemical process. The experimental observations suggest that the dissolution-electrodeposition mechanism appears to be the dominant mechanism under the experimental conditions employed in this study. This facile process may open a new green electricitybased route for the production of dendritic iron crystals from iron(III) oxide in alkaline media.

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“…14 The heat from the laser in combination with the hydrogen reduces this iron-oxide back to iron using the following redox relations: 21,22 …”

Section: B Catalystmentioning

confidence: 99%

Closed-loop control of laser assisted chemical vapor deposition growth of carbon nanotubes

Burgt

Bellouard

Mandamparambil

et al. 2012

Journal of Applied Physics

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Laser-assisted chemical vapor deposition growth is an attractive mask-less process for growing locally aligned nanotubes in selected places on temperature sensitive substrates. An essential parameter for a successful and reproducible synthesis of nanotubes is the temperature during growth. Here, we demonstrate a temperature feedback control mechanism based on the dynamic, in situ monitoring of the infrared radiation coupled with reflectivity information. With the information provided by these sensors, an infrared laser, focused on a silicon substrate covered with aluminum-oxide and iron catalyst layers, can be controlled. The growth takes place in a gaseous mixture of argon (carrier gas), hydrogen (process gas), and ethylene (carbon-containing gas). Scanning electron microscopy and Raman spectroscopy analysis demonstrate the excellent reproducibility of the closed-loop control process over multiple experiments. Furthermore, we developed a unique method to identify the onset for catalyst formation and activation by monitoring the fluctuation of the reflected laser beam.

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Kinetics of reduction of iron oxides by H2

Cited by 405 publications

References 22 publications

Influence of CaO and SiO2 on the Reducibility of W^|^uuml;stite Using H2 and CO Gas

Influence of CaO and SiO2 on the Reducibility of W^|^uuml;stite Using H2 and CO Gas

Electroreduction of Iron(III) Oxide Pellets to Iron in Alkaline Media: A Typical Shrinking-Core Reaction Process

Closed-loop control of laser assisted chemical vapor deposition growth of carbon nanotubes

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