Effect of Applied Voltage on Electroreduction with Controlled Oxygen Flow of Molten Slag Containing FeO at 1723 K

Gao, Yunming; Duan, Chao; Yang, Yingbin; Ruan, Dong; Yang, Chuanghuang; Hong, Chuan

doi:10.2355/isijinternational.isijint-2014-826

Cited by 9 publications

(9 citation statements)

References 47 publications

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“…It is observed that large grains (cubic ZrO2) still remain in the MSZ (in Fig. 9 small grains denote the monoclinic phase and large grains the cubic phase, which was confirmed by SEM and EDS in our previous work 33 ), and the interface region of the MSZ touching the slag also shows good integrity without any sign of new phase formation or corrosion. Besides, the calculation from the Factsage thermodynamic software shows that the decomposition potential of MSZ is about 2.0 V at 1723 K. So the MSZ cannot be electrolyzed under the conditions of the temperature and the applied potential.…”

Section: Pccp Papersupporting

confidence: 48%

“…In contrast, iron dendrite could be formed when the iron rod was used as the cathode in a similar previous study. 33 It is reasonable to deduce that the formation of the loose layer as the Fe-Ir alloy is the result of interdiffusion of the deposited Fe and Ir. At -1.30 V, the loose layer at the electrode is a Si-Fe-Ir alloy, indicating co-deposition of iron and silicon.…”

Section: Pccp Papermentioning

confidence: 99%

“…These zirconia-based solid electrolytes have been widely used not only in metallurgical industry, but also fundamental research, [23][24][25][26][27][28][29][30][31][32][33][34][35][36] including determination of activity 23,24 and diffusion coefficient 25,26 of oxygen in metal melt, determination of activity of FeO in molten slag, 27,28 electrolytic refining of metal melt, 29,30 and extraction of metal from dissolved oxide in molten salt or molten slag. [31][32][33] In this work, a magnesia-stabilised zirconia (MSZ) solid electrolyte tube was used to accommodate the SiO2-CaO-MgO-Al2O3 molten slag containing FeO. Electrochemical behaviour of iron ions in the molten slag at 1723 K was investigated by combining with a variety of electrochemical means, including CV, square wave voltammetry (SWV), chronopotentiometry (CP), and potentiostatic electrolysis (PE).…”

Section: Introductionmentioning

confidence: 99%

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Magnesia-stabilised zirconia solid electrolyte assisted electrochemical investigation of iron ions in a SiO₂–CaO–MgO–Al₂O₃molten slag at 1723 K

Gao

Yang

Zhang

et al. 2017

Phys. Chem. Chem. Phys.

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Production of metallic iron through molten oxide electrolysis using inert electrodes is an alternative route for fast ironmaking without CO2 emissions. The fact that many inorganic oxides melt at ultrahigh temperatures (>1500 K) challenges conventional electro-analytical techniques used in aqueous, organic and molten salt electrolytes. However, in order to design a feasible and effective electrolytic process, it is necessary to best understand the electrochemical properties of iron ions in molten oxide electrolytes. In this work, a magnesia-stabilised zirconia (MSZ) tube with a closed end was used to construct an integrated three-electrode cell with the "MSZ | Pt | O2 (air)" assembly functioning as the solid electrolyte, the reference electrode and also the counter electrode. Electrochemical reduction of iron ions was systematically investigated on an iridium (Ir) wire working electrode in the SiO2-CaO-MgO-Al2O3 molten slag at 1723 K by cyclic voltammetry (CV), square wave voltammetry (SWV), chronopotentiometry (CP) and potentiostatic electrolysis (PE). The results show that the electroreduction of the Fe 2+ ion to Fe on the Ir electrode in the molten slag follows a single twoelectron transfer step, and the rate of the process is diffusion controlled. The peak current on the obtained CVs is proportional to the concentration of the Fe 2+ ion in the molten slag and the square root of scan rate. The diffusion coefficient of Fe 2+ ions in the molten slag containing 5 wt% FeO at 1723 K was derived to be (3.43 ± 0.06)×10 -6 cm 2 s -1 from CP analysis. However, a couple of following processes, i.e. alloy formation on the Ir electrode surface and interdiffusion were found to affect the kinetics of iron deposition. An ECC mechanism is proposed to account for the CV observations. The findings from this work confirm that zirconia-based solid electrolytes can play an important role in electrochemical fundamental research in high temperature molten slag electrolytes.

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Section: Pccp Papersupporting

confidence: 48%

Section: Pccp Papermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magnesia-stabilised zirconia solid electrolyte assisted electrochemical investigation of iron ions in a SiO₂–CaO–MgO–Al₂O₃molten slag at 1723 K

Gao

Yang

Zhang

et al. 2017

Phys. Chem. Chem. Phys.

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“…Due to the molten slags ionic structures, it can improve the cleaning process by the application of the electro-capillary effect in accelerating the copper-matte drops settling [8][9][10][11][12][13]. The behaviors of matte droplets in the molten slags under a vertical electric field are studied by Choo et al, and the slags and matte composition can significantly affect the migration direction of the droplets [12][13].…”

Section: Introductionmentioning

confidence: 99%

Continuous cleaning process of molten copper slags in a channel reactor under the external electric field

Zhang

2019

E3S Web Conf.

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Continuous cleaning process of the molten copper slags in a channel reactor under a vertical electric field is proposed. The copper-matte settling velocity under the vertical electric field is much faster than that only under the gravity in the molten slags, and the electric field can also accelerate the magnetite reduction. Cu content in the slag can fall below 0.35 wt. % during the continuous cleaning process, which exceeds much more existing slag treatment process. In addition, the behaviours of some other heavy metal elements in the molten slags during the continuous process are also discussed.

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“…[24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] For example, they are used to help the determination of the activity [24,25] and diffusion coefficient [26,27] of oxygen in molten metals, and of the activity of FeO in molten slags, [28,29] to assist the electrolytic refining of molten metals, [30,31] and the extraction of metals from metal oxides dissolved in molten salts and slags. [32][33][34][35][36] Furthermore, in order to conduct electrochemical research on molten media containing O 2ions, MSZ or YSZ can also be used to construct a stable RE, such as the "O 2-| MSZ (or YSZ) | Pt | O2 (air)" RE at high temperatures. [37][38][39] Since the O2 partial pressure is very stable in the air, either stationary or flowing, the O 2-| MSZ (or YSZ) | Pt | O2 (air) RE is preferred for its good stability and reproducibility.…”

Section: Introductionmentioning

confidence: 99%

Yttria-Stabilized Zirconia Aided Electrochemical Investigation on Ferric Ions in Mixed Molten Calcium and Sodium Chlorides

Gao

Lao

et al. 2018

Metall Mater Trans B

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Electrolytic reduction of dissolved iron oxide to metal iron in molten salts with an inert anode is an alternative short route for steelmaking without CO2 emissions. A novel and simple integrated yttria-stabilized zirconia (YSZ) cell was constructed from a YSZ tube with a closed end. The YSZ tube played multiple functions, including the container for the molten salts, the solid electrolyte membrane in the O 2-| YSZ | Pt | O2 (air) reference electrode (RE), and the solid electrolyte membrane between the working and counter electrodes (WE and CE). Electrochemical behavior of ferric ions (Fe 3+) that were formed by dissolution of 0.5 wt pct Fe2O3 in the molten CaCl2-NaCl eutectic mixture was investigated on a Pt WE at 1273 K by various electrochemical techniques including cyclic voltammetry, linear scan voltammetry, square wave voltammetry, chronopotentiometry, chronoamperometry, and potentiostatic electrolysis. Analysis of the mechanism of electrode reactions was further assisted by scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. Some electrochemical parameters were obtained, including the number of exchanged electrons and the diffusion coefficient of ferric ions in the mixed molten salts. The results from various electrochemical techniques are in good agreement with each other, and show that the electrochemical reduction of Fe 3+ to Fe in the molten salt mixture could be a single three-electron transfer step and diffusion controlled reaction that was also possibly reversible. This work may form the foundation for extraction of iron and alloys from molten salts and also provid a stable O 2-| YSZ | Pt | O2 (air) RE with wide applicability for investigation on electrochemical properties of other electroactive metal oxides in molten salts.

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Effect of Applied Voltage on Electroreduction with Controlled Oxygen Flow of Molten Slag Containing FeO at 1723 K

Cited by 9 publications

References 47 publications

Magnesia-stabilised zirconia solid electrolyte assisted electrochemical investigation of iron ions in a SiO₂–CaO–MgO–Al₂O₃molten slag at 1723 K

Magnesia-stabilised zirconia solid electrolyte assisted electrochemical investigation of iron ions in a SiO₂–CaO–MgO–Al₂O₃molten slag at 1723 K

Continuous cleaning process of molten copper slags in a channel reactor under the external electric field

Yttria-Stabilized Zirconia Aided Electrochemical Investigation on Ferric Ions in Mixed Molten Calcium and Sodium Chlorides

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Effect of Applied Voltage on Electroreduction with Controlled Oxygen Flow of Molten Slag Containing FeO at 1723 K

Cited by 9 publications

References 47 publications

Magnesia-stabilised zirconia solid electrolyte assisted electrochemical investigation of iron ions in a SiO2–CaO–MgO–Al2O3molten slag at 1723 K

Magnesia-stabilised zirconia solid electrolyte assisted electrochemical investigation of iron ions in a SiO2–CaO–MgO–Al2O3molten slag at 1723 K

Continuous cleaning process of molten copper slags in a channel reactor under the external electric field

Yttria-Stabilized Zirconia Aided Electrochemical Investigation on Ferric Ions in Mixed Molten Calcium and Sodium Chlorides

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Product

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Magnesia-stabilised zirconia solid electrolyte assisted electrochemical investigation of iron ions in a SiO₂–CaO–MgO–Al₂O₃molten slag at 1723 K

Magnesia-stabilised zirconia solid electrolyte assisted electrochemical investigation of iron ions in a SiO₂–CaO–MgO–Al₂O₃molten slag at 1723 K