Electrochemical Reactions on Metal-Matrix Composite Anodes for Metal Electrowinning

Mohammadi, Maysam; Mohammadi, Farzad; Alfantazi, Akram

doi:10.1149/2.081304jes

Cited by 34 publications

(18 citation statements)

References 73 publications

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“…Generally speaking, the rst slope is due to the oxidation reaction of PbSO 4 / PbO 2 and the low extent of OER, while the second slope is mainly attributed to the OER on the anodes surface as well as in the pores of anodes. 45 To be precise, the Tafel slope of Pb-Co with different fraction of Co is similar, but lower than that of Pb-Ca-Sn alloy. This may be due to Co promotes the charge transfer and the OER rate.…”

Section: Tafel Curves and Kinetic Parameters For Oxygen Evolutionmentioning

confidence: 94%

Polarization behavior of Pb–Co powder-pressed alloy for electrowinning

Wang

Zhou

et al. 2018

RSC Adv.

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Section: Tafel Curves and Kinetic Parameters For Oxygen Evolutionmentioning

confidence: 94%

Polarization behavior of Pb–Co powder-pressed alloy for electrowinning

Wang

Zhou

et al. 2018

RSC Adv.

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“…This observation is matched with the cyclic voltammetry studies of the polarized Pb-MnO 2 composite compared to other lead-based alloys. 9 A wide anodic peak appeared at negative potentials of the obtained voltammograms ( Figure 14 and Figure 15). This peak, which is marked as C2, corresponds to the reduction of Pb(II) compounds to lead.…”

Section: Potentiostatic-lsv Studiesmentioning

confidence: 94%

“…The composite anodes containing MnO 2 particles (Pb-MnO 2 ) have shown lower oxygen evolution overpotential than the conventional lead-based anodes, contributing to lower energy consumption of the electrowinning process in sulfuric acid electrolyte. [8][9][10] According to the results published by the authors, the operating potentials of the Pb-MnO 2 anode containing 10 wt.% MnO 2 particles at 500 A/m 2 was approximately 130 mV lower than that of the PbAg (0.75 wt.%) conventional anode. 8 The electrowinning process usually operates at high current density, which causes high anode potential, i.e.…”

Section: Introductionmentioning

confidence: 91%

“…As a result of the presence of MnO 2 particles in the composite anode, oxygen evolution started at lower anodic potentials compared to the PbAg alloy. 8,9 Therefore, peak II was hidden by the OER branch in the cyclic voltammograms of the Pb-MnO 2 composite.…”

Section: Cyclic Voltammetry Studymentioning

confidence: 99%

“…Disk-shaped samples with a diameter of 16 mm were pressed at 300 MPa for 5 minutes in a stainless steel mold at room temperature. The fabrication process of the Pb-MnO 2 composites has been explained in detail in previous publications by the authors 2,8,9. An industrially-supplied PbAg alloy was used as a benchmark for comparison in some of the experiments.…”

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confidence: 99%

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Corrosion Assessment of a Lead-Based Composite in Sulfuric Acid Electrolytes

2016

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In this study, corrosion performances of the Pb-MnO 2 composite in a sulfuric acid electrolyte solution at a wide range of anodic potentials were investigated. The regarding effects of manganese ions as an additive to the electrolyte were also studied. An industrially-supplied PbAg alloy was examined in some cases and the obtained results were used as benchmarks for comparison. Oxidation of these materials and properties of the formed anodic layers were examined using electrochemical techniques including electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), potentiostatic polarization and linear sweep voltammetry (LSV). Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy were employed to characterize the anodic layers. The presence of MnO 2 particles in the Pb-MnO 2 caused the open circuit potential of lead to increase from the PbSO 4 potential region to the PbO potential region, contributing to different composition of the anodic layer and higher charge transfer resistances of the corrosion layer in comparison with those of the PbAg alloy. The charge transfer resistance of the composite increased with potential within the PbO/PbSO 4 potential region. At the PbO 2 potential region, the Pb-MnO 2 composite anode showed a larger amount of PbO 2 in the corrosion layer than the PbAg alloy in the Mn-free electrolyte. The presence of manganese ions inhibited the formation of PbO 2 on the anodes, an effect that was more significant on the composite anode. Regardless of the electrolyte composition, the amount of PbO 2 corrosion product on the composite anode increased with the polarization time and the applied potential.

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Influence of Mn2+ ions on the corrosion mechanism of lead-based anodes and the generation of heavy metal anode slime in zinc sulfate electrolyte

Zhang

Duan

Jiang

et al. 2018

Environ Sci Pollut Res

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The influence of Mn ions on the generation of heavy metal anode slime during zinc electrolysis industry was extensively investigated using several electrochemical methods, electron microscope technologies, and particle size analysis. Results showed that the Mn could obviously promote oxygen evolution reaction (OER) and thereby weaken oxidation efficiency of Mn (η) and dissolution of Pb. The significant improvement in kinetic parameters for OER was found in electrolytes of 1 and 3 g/L Mn, but became unstable as the Mn concentration increased to 10 g/L. This result was correlated with much different properties of oxide layers that its changes of microstructure are involved in, since it confirmed that the positive role of compact oxide layers in contributing to high corrosion resistance and activity for OER, but excessive Mn, resulted in its micromorphology of overthickness and instability. Such differences resulted from the effect of the Mn concentration fluctuation on kinetic rates of the nucleation growth process. The formation and adsorption of intermediate MnO-OH identified as the controlled step for Mn catalyzing OER was also recommended. The generation mechanism of anode slime was found to be changed in essence due to varying Mn concentrations. In electrolyte of 1 g/L Mn, results revealed that the root cause of excessive small suspended anode slime (around 20 μm) was the change of the initial pathway of Mn electro-oxidation, whereas, it showed great improvement in the settling performance as the Mn concentration was increased to 10 g/L. Considering the potential of optimizing Mn concentrations as a cleaner approach to control anode slime, deepening the understanding of the impact mechanism of Mn can provide new insights into intervention in the generation of anode slime.

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Electrochemical Reactions on Metal-Matrix Composite Anodes for Metal Electrowinning

Cited by 34 publications

References 73 publications

Polarization behavior of Pb–Co powder-pressed alloy for electrowinning

Polarization behavior of Pb–Co powder-pressed alloy for electrowinning

Corrosion Assessment of a Lead-Based Composite in Sulfuric Acid Electrolytes

Influence of Mn2+ ions on the corrosion mechanism of lead-based anodes and the generation of heavy metal anode slime in zinc sulfate electrolyte

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