The effect of manganese on lead anodes in zinc electrowinning

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Helsinki University of Technology | Diplomityö
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Date

2005

Department

Materiaalitekniikan osasto

Major/Subject

Korroosionestotekniikka

Mcode

Mak-85

Degree programme

Language

en

Pages

65+11

Series

Abstract

In the literature survey part of this study, electrolysis with a focus on electrowinning was introduced. Anode materials for zinc electrowinning and the reactions occurring at the anode, cathode and in the electrolyte were discussed. The experimental part of the study began with the construction of a system for measuring the weight change of an electrode during electrolysis on the laboratory scale. The largest challenge was to construct a system to feed the current that did not cause a weight change of the electrode, which was measured with a microbalance. The measuring system was then used to test different anodes and the effect of different manganese concentrations in the electrolyte on the anode weight was investigated. The anodes tested were Pb-0.6Ag, with and without grooves forming different patterns and a mixed metal oxide (MMO) anode, which had titanium as the base material and IrO2-Ta2O5 as coating. The concentrations of manganese tested were 0, 0.5, 1, 3 and 5 g/dm3. The tests showed promising results for the patterned Pb-0.6Ag anodes as the formation of manganese dioxide in the electrolyte decreased substantially. There was an increase in the amount of deposit formed on the electrode. The patterning might decrease the stress in the PbO2/MnO2 surface layer and decreases the amount of metal oxides lost from the surface. Discharging of the anode deposits was tested and showed that the system was sensitive enough to follow the dissolution of the different layers on the anodes. With this information a clearer view the mechanisms for the formation and dissolution of the layers and which substances are involved, could be received.

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Supervisor

Aromaa, Jari

Thesis advisor

Barker, Michael
Pajunen, Lauri

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Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-2020120452181

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[dipl] Teknillinen korkeakoulu / TKK