Crystal Orientation of Iron Produced by Electrodeoxidation of Hematite Particles

Kongstein, Ole Edvard; Haarberg, Geir Martin

doi:10.1149/05052.0103ecst

Cited by 15 publications

(16 citation statements)

References 13 publications

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“…This suggests that the reduction of Fe2O3 to metallic iron occurred in one step. This result is expected and agrees with previous studies (10)(11)(12)(13); as Fe2O3 particles were present and attached to the current collector in the cavity electrode arrangement. The anodic peak corresponding to metallic iron dissolution can also be clearly seen.…”

Section: Cyclic Voltammetrysupporting

confidence: 93%

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Electrodeoxidation of Iron Oxide in Aqueous NaOH Electrolyte

Haarberg

Khalaghi

2020

Meet. Abstr.

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The production of iron and steel contributes to ~10 % of global CO2 emissions. Electrolysis is an alternative route to eliminate CO2 formation. Experiments were carried out in NaOH-H2O (50-50 wt%) electrolyte with a suspension of Fe2O3 particles at ~100 °C. A rotating disk electrode was used as the cathode. Different cathode substrates of different graphite qualities and silver were used. The current efficiency for iron deposition was consistently higher than 90 %. Silver was found to be an excellent substrate for good quality deposits. Cathodes in the form of pellets of hematite were also found to be reduced to iron by electrodeoxidation in the same electrolyte. Bauxite residue is a waste product from the Bayer process to produce aluminium oxide. The high content of iron oxide makes it a candidate for electrodeoxidation in a similar way.

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Section: Cyclic Voltammetrysupporting

confidence: 93%

“…Figure 6 (a) to (c) are images of iron deposits obtained after electrowinning of Fe2O3. The microstructure of deposited iron was similar to those obtained in previous studies (4,12). The iron crystals were made up of six twin crystals; the twin crystals were tetrahedron-shaped and converged at an apex (Figure 6-a).…”

Section: Microscopy Studiessupporting

confidence: 79%

Electrodeoxidation of Iron Oxide in Aqueous NaOH Electrolyte

Haarberg

Khalaghi

2020

Meet. Abstr.

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“…Alkali concentration, cell operating temperature, and iron oxide load are the main factors determining the contribution of each mechanism to the overall process. Working electrodes (WE) as Frontiers in Materials frontiersin.org graphite (Allanore et al, 2007;Tokushige et al, 2013;Feynerol et al, 2017;Maihatchi et al, 2020), Cu rod (Zou et al, 2015a), Fe rod (Ivanova et al, 2015), stainless steel plates (Koutsoupa et al, 2021a;2021b) or Ni grids (Lopes et al, 2020(Lopes et al, , 2021(Lopes et al, , 2022 are usually used. Dendritic/star-like shape Fe deposits are often obtained after the electrochemical reduction of iron oxides in alkaline suspensions (Figure 1A).…”

Section: Electroreduction From Iron Oxide-based Suspensionsmentioning

confidence: 99%

“…HER potentials tend to increase for higher cathodic values when the alkaline electrolyte concentrations increase (Nickell et al, 2006). Some authors have been employing 18 M NaOH electrolyte solutions (Allanore et al, 2008(Allanore et al, , 2010cTokushige et al, 2013) to minimize the HER effect. Although increasing the concentration of the electrolyte seems to decrease the HER impact and, consequently, the Faradaic efficiency increase, it does not guarantee itself a high efficiency level as, for example, ~70% of efficiency was obtained at 18 M NaOH (Allanore et al, 2007) and ~80% at 10 M NaOH (Ivanova et al, 2015).…”

Section: Factors Affecting the Faradaic Efficiency Of The Electroredu...mentioning

confidence: 99%

Prospects and challenges of the electrochemical reduction of iron oxides in alkaline media for steel production

et al. 2022

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Steelmaking industries have been facing strict decarbonization guidelines. With a net zero carbon emissions target, European policies are expected to be accomplished before 2050. Traditional steelmaking industry still operates by the carbothermic reduction of iron ores for steel production. Consequently, the steel sector is responsible for a large amount of CO2 emissions, accounting for up to 9% of the CO2 worldwide emissions. In this scope, the electrochemical reduction or electrolysis of iron oxides into metallic iron in alkaline media arises as a promising alternative technology for ironmaking. Significant advantages of this technology include the absence of CO2 emissions, non-polluting by-products such as hydrogen and oxygen gases, lower temperature against the conventional approach (∼100°C versus 2000°C) and lower electric energy consumption, where around 6 GJ per ton of iron manufactured can be spared. The present minireview discusses the progress on the electrochemical reduction of iron oxides in alkaline media as a green steelmaking route. A historical overview of the global steelmaking against recent developments and challenges of the novel technology is presented, and the fundamental mechanisms of iron oxide reduction to iron and alternative iron feedstocks are discussed. Factors affecting the Faradaic efficiencies of the alkaline electroreduction of iron oxide suspensions or iron oxide bulk ceramics are also explored, focusing on the concurrent hydrogen evolution reaction. Overall, if scrutinized, this technology may become a breaking point for the steel industry sector.

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“…Actually, the morphology of the electroreduction-generated iron can be controlled by varying the operation conditions. [57] Dissolution reactions: …”

Section: Solid State Electroreduction Mechanismmentioning

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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Crystal Orientation of Iron Produced by Electrodeoxidation of Hematite Particles

Cited by 15 publications

References 13 publications

Electrodeoxidation of Iron Oxide in Aqueous NaOH Electrolyte

Electrodeoxidation of Iron Oxide in Aqueous NaOH Electrolyte

Prospects and challenges of the electrochemical reduction of iron oxides in alkaline media for steel production

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

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