Electrolytic iron production from alkaline suspensions of solid oxides: compared cases of hematite, iron ore and iron-rich Bayer process residues

Maihatchi, Abdoulaye; Pons, Marie‐Noëlle; Ricoux, Quentin; Goettmann, Frédéric; Lapicque, François

doi:10.5599/jese.751

Cited by 17 publications

(12 citation statements)

References 13 publications

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“…Considering the results of the experiments and the residue characterization, the following mechanism is suggested for high-iron BR leaching in the presence of Fe 2+ ( Figure 12 ). The dissolution of iron-containing minerals is limited by the low solubility of iron in an alkaline solution [ 53 ]. The presence of Fe 2+ promotes the extraction of Al from Al-hematite and Al-goethite via precipitation of magnetite from the solution because a new portion of Fe can be further dissolved.…”

Section: Resultsmentioning

confidence: 99%

High-Iron Bauxite Residue (Red Mud) Valorization Using Hydrochemical Conversion of Goethite to Magnetite

et al. 2022

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Bauxite residue (BR), also known as red mud, is a byproduct of the alumina production using the Bayer process. This material is not used to make iron or other iron-containing products worldwide, owing to its high content of sodium oxide and other impurities. In this study, we investigated the hydrochemical conversion of goethite (FeOOH) to magnetite (Fe3O4) in high-iron BR from the Friguia alumina refinery (Guinea) by Fe2+ ions in highly concentrated alkaline media. The simultaneous extraction of Al and Na made it possible to obtain a product containing more than 96% Fe3O4. The results show that the magnetization of Al-goethite and Al-hematite accelerates the dissolution of the Al from the iron mineral solid matrix and from the desilication product (DSP). After ferrous sulfate (FeSO4·7H2O) was added directly at an FeO:Fe2O3 molar ratio of 1:1 at 120 °C for 150 min in solution with the 360 g L−1 Na2O concentration, the alumina extraction ratio reached 96.27% for the coarse bauxite residue size fraction (Sands) and 87.06% for fine BR obtained from red mud. The grade of iron (total iron in the form of iron elements) in the residue can be increased to 69.55% for sands and 58.31% for BR. The solid residues obtained after leaching were studied by XRD, XRF, TG-DTA, VSM, Mössbauer spectroscopy, and SEM to evaluate the conversion and leaching mechanisms, as well as the recovery ratio of Al from various minerals. The iron-rich residues can be used in the steel industry or as a pigment.

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Section: Resultsmentioning

confidence: 99%

High-Iron Bauxite Residue (Red Mud) Valorization Using Hydrochemical Conversion of Goethite to Magnetite

et al. 2022

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“…[15] The feasibility of the method for lower grades of iron oxide feedstocks such as pseudobrookite (Fe 2 TiO 5 ), [17] titanomagnetite iron sand (Fe 2 + (Fe 3 + , Ti) 2 O 4 ), [18] and red mud (iron-rich waste from the aluminum industry) was also shown. [19,20] Nevertheless, the reported inconsistent range of Faradaic efficiencies in previous studies (5-100 %) [21] lacked differentiation between anode types, experimental environments, and cell configurations. In contrast, we suspected that these process parameters likely influence the overall electrolysis performance.…”

Section: Introductionmentioning

confidence: 95%

“…investigated the impacts of the cathode‐anode relative configuration (the type of connection between the cathode and current collector) [15] . The feasibility of the method for lower grades of iron oxide feedstocks such as pseudobrookite (Fe 2 TiO 5 ), [17] titanomagnetite iron sand (Fe 2+ (Fe 3+ , Ti) 2 O 4 ), [18] and red mud (iron‐rich waste from the aluminum industry) was also shown [19,20] …”

Section: Introductionmentioning

confidence: 99%

Deoxidation Electrolysis of Hematite in Alkaline Solution: Impact of Cell Configuration and Process Parameters on Reduction Efficiency

Fayaz,

Bösing,

La Mantia

et al. 2023

ChemElectroChem

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Recent research is investigating deoxidation electrolysis for eco‐friendly iron extraction. However, many parameters are not fully understood and inconsistencies in reported Faradaic efficiencies pose challenges for finding the most suitable experimental conditions. Thus, we investigated the dependence of hematite reduction efficiency on process parameters and cell configurations. Firstly, we studied the influence of the anode material. The experiments included cyclic voltammetry to identify the redox potentials, electrolysis, and X‐ray diffraction followed by Rietveld refinement to analyze the pellets after electrolysis. In some cases, scanning electron microscopy equipped with energy‐dispersive X‐ray spectroscopy was employed to track the elemental map of the cathode pellets. Nickel/iron alloy, a well‐known oxygen‐evolving electrocatalyst material, clearly outperformed other anode materials, namely graphite, titanium, nickel, and platinum. Subsequent investigations explored the impact of an inert atmosphere and anode‐cathode decoupling on Faradaic efficiency. The findings indicated that the decline in Faradaic efficiency cannot be solely attributed to the hydrogen evolution reaction, but also to other parasitic effects such as carbon cycles. Additionally, we employed energy consumption measurements as a mean of comparing the process against established extractive methodologies. The required energy consumption by electrolysis is up to 46 % lower than that of a blast furnace.

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“…Studies on Fe 3 O 4 [9,14] and FeOOH [14] were also performed, showing, however, generally lower efficiencies. Different feedstocks for the electrochemical reduction for steelmaking are now under consideration, including iron-rich waste such as red mud from the aluminium industry [16,17]. The role of some specific elements like Al [18,19] and Mg [20] on the reduction mechanisms of hematite-or magnetite-based compounds were also studied.…”

Section: Introductionmentioning

confidence: 99%

Prospects of Using Pseudobrookite as an Iron-Bearing Mineral for the Alkaline Electrolytic Production of Iron

et al. 2022

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The alkaline electrolytic production of iron is gaining interest due to the absence of CO2 emissions and significantly lower electrical energy consumption when compared with traditional steelmaking. The possibility of using an iron-bearing pseudobrookite mineral, Fe2TiO5, is explored for the first time as an alternative feedstock for the electrochemical reduction process. To assess relevant impacts of the presence of titanium, similar electroreduction processes were also performed for Fe2TiO5·Fe2O3 and Fe2O3. The electroreduction was attempted using dense and porous ceramic cathodes. Potentiostatic studies at the cathodic potentials of −1.15–−1.30 V vs. an Hg|HgO|NaOH reference electrode and a galvanostatic approach at 1 A/cm2 were used together with electroreduction from ceramic suspensions, obtained by grinding the porous ceramics. The complete electroreduction to Fe0 was only possible at high cathodic polarizations (−1.30 V), compromising the current efficiencies of the electrochemical process due to the hydrogen evolution reaction impact. Microstructural evolution and phase composition studies are discussed, providing trends on the role of titanium and corresponding electrochemical mechanisms. Although the obtained results suggest that pseudobrookite is not a feasible material to be used alone as feedstock for the electrolytic iron production, it can be considered with other iron oxide materials and/or ores to promote electroreduction.

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Electrolytic iron production from alkaline suspensions of solid oxides: compared cases of hematite, iron ore and iron-rich Bayer process residues

Cited by 17 publications

References 13 publications

High-Iron Bauxite Residue (Red Mud) Valorization Using Hydrochemical Conversion of Goethite to Magnetite

High-Iron Bauxite Residue (Red Mud) Valorization Using Hydrochemical Conversion of Goethite to Magnetite

Deoxidation Electrolysis of Hematite in Alkaline Solution: Impact of Cell Configuration and Process Parameters on Reduction Efficiency

Prospects of Using Pseudobrookite as an Iron-Bearing Mineral for the Alkaline Electrolytic Production of Iron

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