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Effect of halides in the electrowinning of zinc. II. Corrosion of lead-silver anodes

Nicol, M., Akilan, C., Tjandrawan, V. and Gonzalez, J.A. (2017) Effect of halides in the electrowinning of zinc. II. Corrosion of lead-silver anodes. Hydrometallurgy, 173 . pp. 178-191.

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Link to Published Version: https://doi.org/10.1016/j.hydromet.2017.08.017
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Abstract

This paper summarizes experimental results obtained from a series of laboratory scale electrowinning tests conducted over 5 months to quantify the effects of halides (chloride, fluoride and bromide) on the performance and corrosion of lead-silver anodes under conditions similar to those used during the electrowinning of zinc. The parameters investigated include operating anode potential, corrosion rate and anode scale/cell mud generation rates. Information was also obtained on the consumption of halides and manganese ions and the composition of the anode scale and cell mud.

The results have confirmed plant observations of excessive anode corrosion and chlorine emissions at a chloride concentration of 400 mg/L but not at a concentration of 200 mg/L. It has also confirmed the importance of maintaining a suitable manganese(II) concentration in the electrolyte. Bromide and fluoride ions, albeit at lower concentrations, do not have measurable effects on anode corrosion.

Although a definitive explanation for enhanced local corrosion at high chloride concentrations has not been advanced, the nature of the accelerated corrosion suggests that a crevice-like corrosion process is responsible for localized massive corrosion. This has been attributed to the presence of high acidity and permanganate ions between the manganese oxide layer and the alloy surface.

Publication Type: Journal Article
Murdoch Affiliation: School of Engineering and Information Technology
Publisher: Elsevier BV
Copyright: © 2017 Elsevier B.V.
URI: http://researchrepository.murdoch.edu.au/id/eprint/38462
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