Investigation of Lead Anodes in the Electrolysis of Zinc Sulfate Solutions

Koenig, A. E.; MacEwan, J. U.; Larsen, E. C.

doi:10.1149/1.3071278

Cited by 9 publications

(3 citation statements)

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“…These two groups of researchers related the observed effects to an unspecified process occurring in preference of the conversion of lead to lead dioxide when cobalt ions are present in the electrolyte. The conclusion was that to keep the anode potential low, one needed to maintain the cobalt concentration by continuous addition of cobalt ions to the electrolyte (Koenig et al, 1941). Tsuruoka (1958) followed a similar approach to study the effect of cobalt ions in a typical zinc electrowinning system and also observed a reduction in lead dissolution when cobalt ions were present in the electrolyte.…”

Section: Introductionmentioning

confidence: 99%

Electrodeposition of lead–cobalt composite coatings electrocatalytic for oxygen evolution and the properties of composite coated anodes for copper electrowinning

Barmi

Nikoloski

2012

Hydrometallurgy

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ÔØ Å ÒÙ× Ö ÔØElectrodeposition of lead-cobalt composite coatings electrocatalytic for oxygen evolution and the properties of composite coated anodes for copper electrowinning Please cite this article as: Barmi, Maryam Jozegholami, Nikoloski, Aleksandar N., Electrodeposition of lead-cobalt composite coatings electrocatalytic for oxygen evolution and the properties of composite coated anodes for copper electrowinning, Hydrometallurgy (2012), doi: 10.1016/j.hydromet.2012.08.005 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. , which is significantly less than the 122 mV dec -1 measured on the conventional PbCaSn anodes. The composite anodes exhibited consistently lower oxygen evolution potentials than the conventional type and the potential remained relatively stable throughout the polarisation period. The reduction in the operating anode potential can be attributed to the presence of cobalt in the surface layer while the decrease in the Tafel slope shows that this reduction can be related to a change in the mechanism of the oxygen evolution reaction. Corrosion rates estimated from 16 h tests showed that the composite coated anodes are more stable than the conventional type during short periods of operation. It was also observed that for the Pb-Co coated anode, both the rate of corrosion and the overpotential for the oxygen evolution reaction can be further reduced by the addition of organic additives such as thiourea. : electrowinning, overpotential, anode, lead, cobalt, thiourea A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT Keywords INTRODUCTIONLead based anodes have been used in the electrowinning of base metals for more than a century due to their low cost and availability. However, the conventional types of lead based anodes, such as PbCaSn, operate at relatively high oxygen overpotential, which results in significant energy consumption, and suffer from corrosion which takes place at a slow rate during the electrowinning process. It is reported that 20-25% of the overall cell energy consumption in tankhouses using conventional lead based anodes is attributed to oxygen evolution overpotential (Schmachtel et al., 2008). On the other hand, the slow corrosion is adding to the cost of anode replacement but, also, leads to contamination of the cathodes with lead from the corrosion product which lowers the quality of the produced cathodes.The development of anodes that can evolve oxygen from acidic sulphate solutions at lower overpotential than on the conventional lead based anode has a long history in the hydrometallurgical research field. This was revisited in the present study, with particul...

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Section: Introductionmentioning

confidence: 99%

Electrodeposition of lead–cobalt composite coatings electrocatalytic for oxygen evolution and the properties of composite coated anodes for copper electrowinning

Barmi

Nikoloski

2012

Hydrometallurgy

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“…1. The fresh anode surface is initially covered with a non-conducting layer of PbSO 4 formed by reaction (2). PbSO 4 is oxidised to the conducting oxide PbO 2 via reaction (3)…”

Section: Introductionmentioning

confidence: 99%

“…Prior research [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] has shown that a small amount (less than 100 ppm) of cobalt ions in the electrolyte results in a lower oxidation rate of the lead alloy, a lower oxygen overpotential (or at least a lower potential of the lead), a smaller amount of PbO 2 on the lead surface [12] and mainly lead sulphate [19] as the oxidation product. The lower potential at the lead anode could lead directly to a lower oxidation rate.…”

Section: Introductionmentioning

confidence: 99%

Influence of cobalt ions on the anodic oxidation of a lead alloy under conditions typical of copper electrowinning

et al. 2007

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The influence of cobalt ions in the solution on the anodic oxidation of a commercial Pb-Ca-Sn alloy under conditions typical of copper electrowinning was studied using cyclic voltammograms and potential decay transients. The cobalt ions changed the structure, morphology and chemical composition of the surface film from a loose porous film to a thin dense film. This change of surface film is the cause for the decreased rate of oxidation for the lead anode in the presence of cobalt ions. The steady state potential of the alloy during anodic oxidation decreased with (i) increasing cobalt ion concentration, (ii) increasing rotation speed, (iii) increasing temperature, (iv) decreasing acid concentration and (v) decreasing current density. The steady state potentials were lower in the presence of cobalt ions. This decrease in the steady state potential may indicate that oxygen evolution is more rapid on the more compact film formed in the presence of cobalt ions. Alternatively, an additional pathway of oxidation may be provided by the cobalt ions.

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