Corrosion of lead anodes in base metals electrowinning

Mirza, A.; Burr, M. F.; Ellis, Timothy W.; Evans, Dennis H.; Kakengela, D.; Webb, Linda J.; Gagnon, Jarod C.; Leclercq, F.; Johnston, AJ

doi:10.17159/2411-9717/2016/v116n6a7

Cited by 27 publications

(7 citation statements)

References 1 publication

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“…This was probably due to reductive dissolution of PbO 2 by Mn(II). 51,52 XRD analysis of the deposited layer after removal from the surface did indicate some α-PbO formation (Figure S3) that was not detected by in situ analysis of the film; α-PbO likely formed below the X-ray penetration depth at the interface with lead.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Manganese Increases Lead Release to Drinking Water

Trueman

Gregory

McCormick

et al. 2019

Environ. Sci. Technol.

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Lead and manganese are regulated in drinking water due to their neurotoxicity. These elements have been reported to co-occur in drinking water systems, in accordance with the metal-scavenging properties of MnO 2 . To the extent that manganese is a driver of lead release, controlling it during water treatment may reduce lead levels. We investigated transport of lead and manganese at the tap in a full-scale distribution system: consistent with a cotransport phenomenon, the two metals were detected in the same colloidal size fraction by size-exclusion chromatography with multielement detection. We also studied the effect of manganese on lead release using a model distribution system: increasing manganese from 4 to 215 μg L −1 nearly doubled lead release. This effect was attributed primarily to deposition corrosion of lead by oxidized phases of manganese, and we used 16S rRNA sequencing to identify bacteria that may be relevant to this process. We explored the deposition corrosion mechanism by coupling pure lead with either MnO 2 -coated lead or pure lead exposed to MnO 2 in suspension; we observed galvanic currents in both cases. We attributed these to reduction of Mn(IV) under anaerobic conditions, and we attributed the additional current under aerobic conditions to oxygen reduction catalyzed by MnO 2 .

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Section: ■ Materials and Methodsmentioning

confidence: 99%

Manganese Increases Lead Release to Drinking Water

Trueman

Gregory

McCormick

et al. 2019

Environ. Sci. Technol.

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“…The anode (half-reaction: H 2 O → ½O 2 + H + + 2e − ) was constructed of 2 mm thick lead doped with 0.06% Cu (Castle Lead Works). The lead plate was passivated by forming PbO 2 on the surface of the plate through EW of a stock solution of 40 g/L Fe (using FeSO 4 ·7H 2 O, ACE Chemicals, 99%) and 60 g/L Na 2 SO 4 (ACE Chemicals, 99%) catholyte with a 60 g/L Na 2 SO 4 anolyte for 5 h [26]. The cathode starter plates (half-reaction: Fe 2+ + 2e − → Fe s ) consisted of 316 stainless steel plates, with the plated deposits being removed after each 5 h run in order to keep the ACD constant throughout testing.…”

Section: Methodsmentioning

confidence: 99%

Electrowinning of Iron from Spent Leaching Solutions Using Novel Anion Exchange Membranes

et al. 2019

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In the Pyror process, electrowinning (EW) is used to recover acid and iron from spent leaching solutions (SLS), where a porous Terylene membrane acts as a separator between the cathode and anode. In this study, a novel anion exchange membrane (AEM)-based EW process is benchmarked against a process without and with a porous Terylene membrane by comparing the current efficiency, specific energy consumption (SEC), and sulfuric acid generation using an in-house constructed EW flow cell. Using an FAP-PK-130 commercial AEM, it was shown that the AEM-based process was more efficient than the traditional processes. Subsequently, 11 novel polybenzimidazole (PBI)-based blend AEMs were compared with the commercial AEM. The best performing novel AEM (BM-5), yielded a current efficiency of 95% at an SEC of 3.53 kWh/kg Fe, which is a 10% increase in current efficiency and a 0.72 kWh/kg Fe decrease in SEC when compared to the existing Pyror process. Furthermore, the use of the novel BM-5 AEM resulted in a 0.22 kWh/kg Fe lower SEC than that obtained with the commercial AEM, also showing mechanical stability in the EW flow cell. Finally, it was shown that below 5 g/L Fe, side reactions at the cathode resulted in a decrease in process efficiency, while 40 g/L yielded the highest efficiency and lowest SECs.

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“…Cobalt is often added to minimize the corrosive degradation of the lead anodes normally used in the electrowinning of base metals from sulphate electrolytes (Mirza et al, 2016). Cobalt ions promote the evolution of oxygen at the anode rather than the oxidation of lead and lower the anode potential in the process (Nikoloski and Nicol, 2008) without materially affecting cathode quality.…”

Section: Additive Concentrationsmentioning

confidence: 99%

Improving cathode morphology at a copper electrowinning plant by optimizing Magnafloc 333 and chloride concentrations

Jacobs

Groot

2019

J. S. Afr. Inst. Min. Metall.

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Electrowinning circuits normally use a number of additives in the electrolyte to promote smooth, compact deposits. These cathodes have the best levels of purity. When electrowinning is coupled to a solvent extraction operation, it is important to minimize the amount of surface-active additives used, as their presence tends to increase phase-disengagement times. In the present work the effects of Magnafloc 333 and chloride concentration were studied with the aim of minimizing the amounts currently being added, while producing an acceptable copper cathode morphology. Magnafloc 333 is a non-ionic polyacrylamide that promotes the plating of smooth, dense copper deposits with minimal impurities. Chloride is added to promote the growth of dense, fine-grained, low-impurity copper deposits on the cathode. A Hull cell was used for the test work. Optimum Magnafloc 333 and chloride concentrations for a synthetic plant electrolyte were found to be 0.01 g/L and 0.025 g/L, respectively. These concentrations were then used to plate laboratory-scale copper cathodes from synthetic and plant electrolytes. Scanning electron microscopy was used to analyse the morphology of the cathodes plated. Many polyhedral crystals were deposited from the synthetic electrolytes, but deposits from the plant electrolytes tended to be spherical, with a large degree of porosity at the lower Magnafloc 333 concentration of 0.01 g/L. Polyhedral deposits were associated with high-quality, smooth plated cathodes.

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Corrosion of lead anodes in base metals electrowinning

Cited by 27 publications

References 1 publication

Manganese Increases Lead Release to Drinking Water

Manganese Increases Lead Release to Drinking Water

Electrowinning of Iron from Spent Leaching Solutions Using Novel Anion Exchange Membranes

Improving cathode morphology at a copper electrowinning plant by optimizing Magnafloc 333 and chloride concentrations

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